Large deviation function for a driven underdamped particle in a periodic potential

NASA Astrophysics Data System (ADS)

Fischer, Lukas P.; Pietzonka, Patrick; Seifert, Udo

2018-02-01

Employing large deviation theory, we explore current fluctuations of underdamped Brownian motion for the paradigmatic example of a single particle in a one-dimensional periodic potential. Two different approaches to the large deviation function of the particle current are presented. First, we derive an explicit expression for the large deviation functional of the empirical phase space density, which replaces the level 2.5 functional used for overdamped dynamics. Using this approach, we obtain several bounds on the large deviation function of the particle current. We compare these to bounds for overdamped dynamics that have recently been derived, motivated by the thermodynamic uncertainty relation. Second, we provide a method to calculate the large deviation function via the cumulant generating function. We use this method to assess the tightness of the bounds in a numerical case study for a cosine potential.

Large microplastic particles in sediments of tributaries of the River Thames, UK - Abundance, sources and methods for effective quantification.

PubMed

Horton, Alice A; Svendsen, Claus; Williams, Richard J; Spurgeon, David J; Lahive, Elma

2017-01-15

Sewage effluent input and population were chosen as predictors of microplastic presence in sediments at four sites in the River Thames basin (UK). Large microplastic particles (1mm-4mm) were extracted using a stepwise approach to include visual extraction, flotation and identification using Raman spectroscopy. Microplastics were found at all four sites. One site had significantly higher numbers of microplastics than other sites, average 66 particles 100g -1 , 91% of which were fragments. This site was downstream of a storm drain outfall receiving urban runoff; many of the fragments at this site were determined to be derived of thermoplastic road-surface marking paints. At the remaining three sites, fibres were the dominant particle type. The most common polymers identified included polypropylene, polyester and polyarylsulphone. This study describes two major new findings: presence of microplastic particles in a UK freshwater system and identification of road marking paints as a source of microplastics. This study is the first to quantify microplastics of any size in river sediments in the UK and links their presence to terrestrial sources including sewage and road marking paints. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Quantifying hyporheic exchange dynamics in a highly regulated large river reach.

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

Hammond, Glenn Edward; Zhou, T; Huang, M

Hyporheic exchange is an important mechanism taking place in riverbanks and riverbed sediments, where river water and shallow groundwater mix and interact with each other. The direction, magnitude, and residence time of the hyporheic flux that penetrates the river bed are critical for biogeochemical processes such as carbon and nitrogen cycling, and biodegradation of organic contaminants. Many approaches including field measurements and numerical methods have been developed to quantify the hyporheic exchanges in relatively small rivers. However, the spatial and temporal distributions of hyporheic exchanges in a large, regulated river reach remain less explored due to the large spatial domains,more » complexity of geomorphologic features and subsurface properties, and the great pressure gradient variations at the riverbed created by dam operations.« less

Accurate modelling of single-particle cryo-EM images quantifies the benefits expected from using Zernike phase contrast

PubMed Central

Hall, R. J.; Nogales, E.; Glaeser, R. M.

2011-01-01

The use of a Zernike-type phase plate in biological cryo-electron microscopy allows the imaging, without using defocus, of what are predominantly phase objects. It is thought that such phase-plate implementations might result in higher quality images, free from the problems of CTF correction that occur when images must be recorded at extremely high values of defocus. In single-particle cryo-electron microscopy it is hoped that these improvements in image quality will facilitate work on structures that have proved difficult to study, either because of their relatively small size or because the structures are not completely homogeneous. There is still a need, however, to quantify how much improvement can be gained by using a phase plate for single-particle cryo-electron microscopy. We present a method for quantitatively modelling the images recorded with 200 keV electrons, for single particles embedded in vitreous ice. We then investigate what difference the use of a phase-plate device could have on the processing of single-particle data. We confirm that using a phase plate results in single-particle datasets in which smaller molecules can be detected, particles can be more accurately aligned and problems of heterogeneity can be more easily addressed. PMID:21463690

Particle Scattering in the Resonance Regime: Full-Wave Solution for Axisymmetric Particles with Large Aspect Ratios

NASA Technical Reports Server (NTRS)

Zuffada, Cinzia; Crisp, David

1997-01-01

Reliable descriptions of the optical properties of clouds and aerosols are essential for studies of radiative transfer in planetary atmospheres. The scattering algorithms provide accurate estimates of these properties for spherical particles with a wide range of sizes and refractive indices, but these methods are not valid for non-spherical particles (e.g., ice crystals, mineral dust, and smoke). Even though a host of methods exist for deriving the optical properties of nonspherical particles that are very small or very large compared with the wavelength, only a few methods are valid in the resonance regime, where the particle dimensions are comparable with the wavelength. Most such methods are not ideal for particles with sharp edges or large axial ratios. We explore the utility of an integral equation approach for deriving the single-scattering optical properties of axisymmetric particles with large axial ratios. The accuracy of this technique is shown for spheres of increasing size parameters and an ensemble of randomly oriented prolate spheroids of size parameter equal to 10.079368. In this last case our results are compared with published results obtained with the T-matrix approach. Next we derive cross sections, single-scattering albedos, and phase functions for cylinders, disks, and spheroids of ice with dimensions extending from the Rayleigh to the geometric optics regime. Compared with those for a standard surface integral equation method, the storage requirement and the computer time needed by this method are reduced, thus making it attractive for generating databases to be used in multiple-scattering calculations. Our results show that water ice disks and cylinders are more strongly absorbing than equivalent volume spheres at most infrared wavelengths. The geometry of these particles also affects the angular dependence of the scattering. Disks and columns with maximum linear dimensions larger than the wavelength scatter much more radiation in the forward

Using depolarization to quantify ice nucleating particle concentrations: a new method

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

Zenker, Jake; Collier, Kristen N.; Xu, Guanglang

We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal sizemore » cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.« less

Using depolarization to quantify ice nucleating particle concentrations: a new method

DOE PAGES

Zenker, Jake; Collier, Kristen N.; Xu, Guanglang; ...

2017-12-01

We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal sizemore » cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.« less

Using depolarization to quantify ice nucleating particle concentrations: a new method

NASA Astrophysics Data System (ADS)

Zenker, Jake; Collier, Kristen N.; Xu, Guanglang; Yang, Ping; Levin, Ezra J. T.; Suski, Kaitlyn J.; DeMott, Paul J.; Brooks, Sarah D.

2017-12-01

We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal size cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.

An experimental and theoretical investigation on torrefaction of a large wet wood particle.

PubMed

Basu, Prabir; Sadhukhan, Anup Kumar; Gupta, Parthapratim; Rao, Shailendra; Dhungana, Alok; Acharya, Bishnu

2014-05-01

A competitive kinetic scheme representing primary and secondary reactions is proposed for torrefaction of large wet wood particles. Drying and diffusive, convective and radiative mode of heat transfer is considered including particle shrinking during torrefaction. The model prediction compares well with the experimental results of both mass fraction residue and temperature profiles for biomass particles. The effect of temperature, residence time and particle size on torrefaction of cylindrical wood particles is investigated through model simulations. For large biomass particles heat transfer is identified as one of the controlling factor for torrefaction. The optimum torrefaction temperature, residence time and particle size are identified. The model may thus be integrated with CFD analysis to estimate the performance of an existing torrefier for a given feedstock. The performance analysis may also provide useful insight for design and development of an efficient torrefier. Copyright © 2014 Elsevier Ltd. All rights reserved.

Autonomous sensor particle for parameter tracking in large vessels

NASA Astrophysics Data System (ADS)

Thiele, Sebastian; Da Silva, Marco Jose; Hampel, Uwe

2010-08-01

A self-powered and neutrally buoyant sensor particle has been developed for the long-term measurement of spatially distributed process parameters in the chemically harsh environments of large vessels. One intended application is the measurement of flow parameters in stirred fermentation biogas reactors. The prototype sensor particle is a robust and neutrally buoyant capsule, which allows free movement with the flow. It contains measurement devices that log the temperature, absolute pressure (immersion depth) and 3D-acceleration data. A careful calibration including an uncertainty analysis has been performed. Furthermore, autonomous operation of the developed prototype was successfully proven in a flow experiment in a stirred reactor model. It showed that the sensor particle is feasible for future application in fermentation reactors and other industrial processes.

Storage in alluvial deposits controls the timing of particle delivery from large watersheds, filtering upland erosional signals and delaying benefits from watershed best management practices

NASA Astrophysics Data System (ADS)

Pizzuto, J. E.; Skalak, K.; Karwan, D. L.

2017-12-01

Transport of suspended sediment and sediment-borne constituents (here termed fluvial particles) through large river systems can be significantly influenced by episodic storage in floodplains and other alluvial deposits. Geomorphologists quantify the importance of storage using sediment budgets, but these data alone are insufficient to determine how storage influences the routing of fluvial particles through river corridors across large spatial scales. For steady state systems, models that combine sediment budget data with "waiting time distributions" (to define how long deposited particles remain stored until being remobilized) and velocities during transport events can provide useful predictions. Limited field data suggest that waiting time distributions are well represented by power laws, extending from <1 to >104 years, while the probability of storage defined by sediment budgets varies from 0.1 km-1 for small drainage basins to 0.001 km-1 for the world's largest watersheds. Timescales of particle delivery from large watersheds are determined by storage rather than by transport processes, with most particles requiring 102 -104 years to reach the basin outlet. These predictions suggest that erosional "signals" induced by climate change, tectonics, or anthropogenic activity will be transformed by storage before delivery to the outlets of large watersheds. In particular, best management practices (BMPs) implemented in upland source areas, designed to reduce the loading of fluvial particles to estuarine receiving waters, will not achieve their intended benefits for centuries (or longer). For transient systems, waiting time distributions cannot be constant, but will vary as portions of transient sediment "pulses" enter and are later released from storage. The delivery of sediment pulses under transient conditions can be predicted by adopting the hypothesis that the probability of erosion of stored particles will decrease with increasing "age" (where age is defined as

Data Compression Algorithm Architecture for Large Depth-of-Field Particle Image Velocimeters

NASA Technical Reports Server (NTRS)

Bos, Brent; Memarsadeghi, Nargess; Kizhner, Semion; Antonille, Scott

2013-01-01

A large depth-of-field particle image velocimeter (PIV) is designed to characterize dynamic dust environments on planetary surfaces. This instrument detects lofted dust particles, and senses the number of particles per unit volume, measuring their sizes, velocities (both speed and direction), and shape factors when the particles are large. To measure these particle characteristics in-flight, the instrument gathers two-dimensional image data at a high frame rate, typically >4,000 Hz, generating large amounts of data for every second of operation, approximately 6 GB/s. To characterize a planetary dust environment that is dynamic, the instrument would have to operate for at least several minutes during an observation period, easily producing more than a terabyte of data per observation. Given current technology, this amount of data would be very difficult to store onboard a spacecraft, and downlink to Earth. Since 2007, innovators have been developing an autonomous image analysis algorithm architecture for the PIV instrument to greatly reduce the amount of data that it has to store and downlink. The algorithm analyzes PIV images and automatically reduces the image information down to only the particle measurement data that is of interest, reducing the amount of data that is handled by more than 10(exp 3). The state of development for this innovation is now fairly mature, with a functional algorithm architecture, along with several key pieces of algorithm logic, that has been proven through field test data acquired with a proof-of-concept PIV instrument.

Large eddy simulation of orientation and rotation of ellipsoidal particles in isotropic turbulent flows

NASA Astrophysics Data System (ADS)

Chen, Jincai; Jin, Guodong; Zhang, Jian

2016-03-01

The rotational motion and orientational distribution of ellipsoidal particles in turbulent flows are of significance in environmental and engineering applications. Whereas the translational motion of an ellipsoidal particle is controlled by the turbulent motions at large scales, its rotational motion is determined by the fluid velocity gradient tensor at small scales, which raises a challenge when predicting the rotational dispersion of ellipsoidal particles using large eddy simulation (LES) method due to the lack of subgrid scale (SGS) fluid motions. We report the effects of the SGS fluid motions on the orientational and rotational statistics, such as the alignment between the long axis of ellipsoidal particles and the vorticity, the mean rotational energy at various aspect ratios against those obtained with direct numerical simulation (DNS) and filtered DNS. The performances of a stochastic differential equation (SDE) model for the SGS velocity gradient seen by the particles and the approximate deconvolution method (ADM) for LES are investigated. It is found that the missing SGS fluid motions in LES flow fields have significant effects on the rotational statistics of ellipsoidal particles. Alignment between the particles and the vorticity is weakened; and the rotational energy of the particles is reduced in LES. The SGS-SDE model leads to a large error in predicting the alignment between the particles and the vorticity and over-predicts the rotational energy of rod-like particles. The ADM significantly improves the rotational energy prediction of particles in LES.

Blended particle filters for large-dimensional chaotic dynamical systems

PubMed Central

Majda, Andrew J.; Qi, Di; Sapsis, Themistoklis P.

2014-01-01

A major challenge in contemporary data science is the development of statistically accurate particle filters to capture non-Gaussian features in large-dimensional chaotic dynamical systems. Blended particle filters that capture non-Gaussian features in an adaptively evolving low-dimensional subspace through particles interacting with evolving Gaussian statistics on the remaining portion of phase space are introduced here. These blended particle filters are constructed in this paper through a mathematical formalism involving conditional Gaussian mixtures combined with statistically nonlinear forecast models compatible with this structure developed recently with high skill for uncertainty quantification. Stringent test cases for filtering involving the 40-dimensional Lorenz 96 model with a 5-dimensional adaptive subspace for nonlinear blended filtering in various turbulent regimes with at least nine positive Lyapunov exponents are used here. These cases demonstrate the high skill of the blended particle filter algorithms in capturing both highly non-Gaussian dynamical features as well as crucial nonlinear statistics for accurate filtering in extreme filtering regimes with sparse infrequent high-quality observations. The formalism developed here is also useful for multiscale filtering of turbulent systems and a simple application is sketched below. PMID:24825886

Inexpensive Tools To Quantify And Map Vegetative Cover For Large-Scale Research Or Management Decisions.

USDA-ARS?s Scientific Manuscript database

Vegetative cover can be quantified quickly and consistently and often at lower cost with image analysis of color digital images than with visual assessments. Image-based mapping of vegetative cover for large-scale research and management decisions can now be considered with the accuracy of these met...

Large scale Brownian dynamics of confined suspensions of rigid particles

NASA Astrophysics Data System (ADS)

Sprinkle, Brennan; Balboa Usabiaga, Florencio; Patankar, Neelesh A.; Donev, Aleksandar

2017-12-01

We introduce methods for large-scale Brownian Dynamics (BD) simulation of many rigid particles of arbitrary shape suspended in a fluctuating fluid. Our method adds Brownian motion to the rigid multiblob method [F. Balboa Usabiaga et al., Commun. Appl. Math. Comput. Sci. 11(2), 217-296 (2016)] at a cost comparable to the cost of deterministic simulations. We demonstrate that we can efficiently generate deterministic and random displacements for many particles using preconditioned Krylov iterative methods, if kernel methods to efficiently compute the action of the Rotne-Prager-Yamakawa (RPY) mobility matrix and its "square" root are available for the given boundary conditions. These kernel operations can be computed with near linear scaling for periodic domains using the positively split Ewald method. Here we study particles partially confined by gravity above a no-slip bottom wall using a graphical processing unit implementation of the mobility matrix-vector product, combined with a preconditioned Lanczos iteration for generating Brownian displacements. We address a major challenge in large-scale BD simulations, capturing the stochastic drift term that arises because of the configuration-dependent mobility. Unlike the widely used Fixman midpoint scheme, our methods utilize random finite differences and do not require the solution of resistance problems or the computation of the action of the inverse square root of the RPY mobility matrix. We construct two temporal schemes which are viable for large-scale simulations, an Euler-Maruyama traction scheme and a trapezoidal slip scheme, which minimize the number of mobility problems to be solved per time step while capturing the required stochastic drift terms. We validate and compare these schemes numerically by modeling suspensions of boomerang-shaped particles sedimented near a bottom wall. Using the trapezoidal scheme, we investigate the steady-state active motion in dense suspensions of confined microrollers, whose

CHARACTERIZATION OF LARGE PARTICLES AT A RURAL SITE IN THE EASTERN UNITED STATES: MASS DISTRIBUTION AND INDIVIDUAL PARTICLE ANALYSIS

EPA Science Inventory

A unique combination of an effective sampler and analysis of individual particles has been used in studying large particles (> 5 micrometers) at a rural site in Eastern United States. The sampler is a modified 'high volume' rotary inertial impactor, which consists of four collect...

Reactor for producing large particles of materials from gases

NASA Technical Reports Server (NTRS)

Flagan, Richard C. (Inventor); Alam, Mohammed K. (Inventor)

1987-01-01

A method and apparatus is disclosed for producing large particles of material from gas, or gases, containing the material (e.g., silicon from silane) in a free-space reactor comprised of a tube (20) and controlled furnace (25). A hot gas is introduced in the center of the reactant gas through a nozzle (23) to heat a quantity of the reactant gas, or gases, to produce a controlled concentration of seed particles (24) which are entrained in the flow of reactant gas, or gases. The temperature profile (FIG. 4) of the furnace is controlled for such a slow, controlled rate of reaction that virtually all of the material released condenses on seed particles and new particles are not nucleated in the furnace. A separate reactor comprised of a tube (33) and furnace (30) may be used to form a seed aerosol which, after passing through a cooling section (34) is introduced in the main reactor tube (34) which includes a mixer (36) to mix the seed aerosol in a controlled concentration with the reactant gas or gases.

The complex aerodynamic footprint of desert locusts revealed by large-volume tomographic particle image velocimetry

PubMed Central

Henningsson, Per; Michaelis, Dirk; Nakata, Toshiyuki; Schanz, Daniel; Geisler, Reinhard; Schröder, Andreas; Bomphrey, Richard J.

2015-01-01

Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal's entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin–Helmholtz instability in the shear layer behind the flapping wings. PMID:26040598

Large-scale numerical simulations of polydisperse particle flow in a silo

NASA Astrophysics Data System (ADS)

Rubio-Largo, S. M.; Maza, D.; Hidalgo, R. C.

2017-10-01

Very recently, we have examined experimentally and numerically the micro-mechanical details of monodisperse particle flows through an orifice placed at the bottom of a silo (Rubio-Largo et al. in Phys Rev Lett 114:238002, 2015). Our findings disentangled the paradoxical ideas associated to the free-fall arch concept, which has historically served to justify the dependence of the flow rate on the outlet size. In this work, we generalize those findings examining large-scale polydisperse particle flows in silos. In the range of studied apertures, both velocity and density profiles at the aperture are self-similar, and the obtained scaling functions confirm that the relevant scale of the problem is the size of the aperture. Moreover, we find that the contact stress monotonically decreases when the particles approach the exit and vanish at the outlet. The behavior of this magnitude is practically independent of the size of the orifice. However, the total and partial kinetic stress profiles suggest that the outlet size controls the propagation of the velocity fluctuations inside the silo. Examining this magnitude, we conclusively argue that indeed there is a well-defined transition region where the particle flow changes its nature. The general trend of the partial kinetic pressure profiles and the location of the transition region results the same for all particle types. We find that the partial kinetic stress is larger for bigger particles. However, the small particles carry a higher fraction of kinetic stress respect to their concentration, which suggest that the small particles have larger velocity fluctuations than the large ones and showing lower strength of correlation with the global flow. Our outcomes explain why the free-fall arch picture has served to describe the polydisperse flow rate in the discharge of silos.

Large scale particle image velocimetry with helium filled soap bubbles

NASA Astrophysics Data System (ADS)

Bosbach, Johannes; Kühn, Matthias; Wagner, Claus

2009-03-01

The application of Particle Image Velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of Computational Fluid Dynamics simulations.

Ionization of the Earth's Upper Atmosphere in Large Energetic Particle Events

NASA Astrophysics Data System (ADS)

Wolff, E.; Burrows, J.; Kallenrode, M.; von Koenig, M.; Kuenzi, K. F.; Quack, M.

2001-12-01

Energetic charged particles ionize the upper terrestrial atmosphere. Sofar, chemical consequences of precipitating particles have been discussed for solar protons with energies up to a few hundred MeV. We present a refined model for the interaction of energetic particles with the atmosphere based on a Monte-Carlo simulation. The model includes higher energies and other particle species, such as energetic solar electrons. Results are presented for well-known solar events, such as July 14, 2000, and are extrapolated to extremely large events, such as Carrington's white light flare in 1859, which from ice cores has been identified ass the largest impulsive NO3 event in the interval 1561 -- 1994 (McCracken et al., 2001).

Uncertainty quantification of seabed parameters for large data volumes along survey tracks with a tempered particle filter

NASA Astrophysics Data System (ADS)

Dettmer, J.; Quijano, J. E.; Dosso, S. E.; Holland, C. W.; Mandolesi, E.

2016-12-01

Geophysical seabed properties are important for the detection and classification of unexploded ordnance. However, current surveying methods such as vertical seismic profiling, coring, or inversion are of limited use when surveying large areas with high spatial sampling density. We consider surveys based on a source and receiver array towed by an autonomous vehicle which produce large volumes of seabed reflectivity data that contain unprecedented and detailed seabed information. The data are analyzed with a particle filter, which requires efficient reflection-coefficient computation, efficient inversion algorithms and efficient use of computer resources. The filter quantifies information content of multiple sequential data sets by considering results from previous data along the survey track to inform the importance sampling at the current point. Challenges arise from environmental changes along the track where the number of sediment layers and their properties change. This is addressed by a trans-dimensional model in the filter which allows layering complexity to change along a track. Efficiency is improved by likelihood tempering of various particle subsets and including exchange moves (parallel tempering). The filter is implemented on a hybrid computer that combines central processing units (CPUs) and graphics processing units (GPUs) to exploit three levels of parallelism: (1) fine-grained parallel computation of spherical reflection coefficients with a GPU implementation of Levin integration; (2) updating particles by concurrent CPU processes which exchange information using automatic load balancing (coarse grained parallelism); (3) overlapping CPU-GPU communication (a major bottleneck) with GPU computation by staggering CPU access to the multiple GPUs. The algorithm is applied to spherical reflection coefficients for data sets along a 14-km track on the Malta Plateau, Mediterranean Sea. We demonstrate substantial efficiency gains over previous methods. [This

Energy Spectra of Very Large Gradual Solar Particle Events

DTIC Science & Technology

2001-01-01

Proceedings of ICRC 2001: 1 c Copernicus Gesellschaft 2001 ICRC 2001 Energy Spectra of Very Large Gradual Solar Particle Events A.J. Tylka 1, C.M.S...Greenbelt, MD 20771, USA 6Department of Astronomy , University of Maryland, College Park, MD 20742 USA Abstract. Energy spectra provide a powerful tool in

Quantifying alteration of river flow regime by large reservoirs in France

NASA Astrophysics Data System (ADS)

Cipriani, Thomas; Sauquet, Eric

2017-04-01

Reservoirs may highly modify river flow regime. Knowing the alterations is of importance to better understand the biological and physical patterns along the river network. However data are not necessary available to carry out an analysis of modifications at a national scale, e.g. due to industrial interests or to lack of measurements. The objective of this study is to quantify the changes in a set of hydrological indices due to large reservoirs in France combining different data sources. The analysis is based on a comparison between influenced discharges (observed discharges) and natural discharges available from: (i) gauging stations available upstream the dam, (ii) regionalization procedures (Sauquet et al., 2008; Sauquet et Catalogne, 2011; Cipriani et al., 2012), or (iii) historical data free from human influence close to the dam location. The impact of large reservoirs is assessed considering different facets of the river flow regime, including flood quantiles, low flow characteristics, quantiles from the flow duration curve and the twelve mean monthly discharges. The departures from the indice representative of natural conditions quantify the effect of the reservoir management on the river flow regime. The analysis is based on 62 study cases. Results show large spread in terms of impact depending on the purposes of the reservoirs and the season of interest. Results also point out inconsistencies in data (water balance between outflow and inflow, downstream of the dam is not warranted) due to uncertainties in mean monthly discharges and to the imperfect knowledge of inflows and outflows. Lastly, we suggest a typology of hydrological alterations based on the purposes of the reservoirs. Cipriani T., Toilliez T., Sauquet E. (2012). Estimating 10 year return period peak flows and flood durations at ungauged locations in France. La Houille Blanche, 4-5: 5-13, doi : 10.1051/lhb/2012024. Sauquet E., Catalogne C. (2011). Comparison of catchment grouping methods for

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.

Large space system: Charged particle environment interaction technology

NASA Technical Reports Server (NTRS)

Stevens, N. J.; Roche, J. C.; Grier, N. T.

1979-01-01

Large, high voltage space power systems are proposed for future space missions. These systems must operate in the charged-particle environment of space and interactions between this environment and the high voltage surfaces are possible. Ground simulation testing indicated that dielectric surfaces that usually surround biased conductors can influence these interactions. For positive voltages greater than 100 volts, it has been found that the dielectrics contribute to the current collection area. For negative voltages greater than-500 volts, the data indicates that the dielectrics contribute to discharges. A large, high-voltage power system operating in geosynchronous orbit was analyzed. Results of this analysis indicate that very strong electric fields exist in these power systems.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

NASA Astrophysics Data System (ADS)

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; Kreidenweis, S. M.

2014-06-01

Data from both laboratory studies and atmospheric measurements are used to develop a simple parametric description for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken to approximate the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A correction factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this correction factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization to the immersion freezing

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

NASA Astrophysics Data System (ADS)

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; Kreidenweis, S. M.

2015-01-01

Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration

Screen-Space Normal Distribution Function Caching for Consistent Multi-Resolution Rendering of Large Particle Data.

PubMed

Ibrahim, Mohamed; Wickenhauser, Patrick; Rautek, Peter; Reina, Guido; Hadwiger, Markus

2018-01-01

Molecular dynamics (MD) simulations are crucial to investigating important processes in physics and thermodynamics. The simulated atoms are usually visualized as hard spheres with Phong shading, where individual particles and their local density can be perceived well in close-up views. However, for large-scale simulations with 10 million particles or more, the visualization of large fields-of-view usually suffers from strong aliasing artifacts, because the mismatch between data size and output resolution leads to severe under-sampling of the geometry. Excessive super-sampling can alleviate this problem, but is prohibitively expensive. This paper presents a novel visualization method for large-scale particle data that addresses aliasing while enabling interactive high-quality rendering. We introduce the novel concept of screen-space normal distribution functions (S-NDFs) for particle data. S-NDFs represent the distribution of surface normals that map to a given pixel in screen space, which enables high-quality re-lighting without re-rendering particles. In order to facilitate interactive zooming, we cache S-NDFs in a screen-space mipmap (S-MIP). Together, these two concepts enable interactive, scale-consistent re-lighting and shading changes, as well as zooming, without having to re-sample the particle data. We show how our method facilitates the interactive exploration of real-world large-scale MD simulation data in different scenarios.

Streamflow Observations From Cameras: Large-Scale Particle Image Velocimetry or Particle Tracking Velocimetry?

NASA Astrophysics Data System (ADS)

Tauro, F.; Piscopia, R.; Grimaldi, S.

2017-12-01

Image-based methodologies, such as large scale particle image velocimetry (LSPIV) and particle tracking velocimetry (PTV), have increased our ability to noninvasively conduct streamflow measurements by affording spatially distributed observations at high temporal resolution. However, progress in optical methodologies has not been paralleled by the implementation of image-based approaches in environmental monitoring practice. We attribute this fact to the sensitivity of LSPIV, by far the most frequently adopted algorithm, to visibility conditions and to the occurrence of visible surface features. In this work, we test both LSPIV and PTV on a data set of 12 videos captured in a natural stream wherein artificial floaters are homogeneously and continuously deployed. Further, we apply both algorithms to a video of a high flow event on the Tiber River, Rome, Italy. In our application, we propose a modified PTV approach that only takes into account realistic trajectories. Based on our findings, LSPIV largely underestimates surface velocities with respect to PTV in both favorable (12 videos in a natural stream) and adverse (high flow event in the Tiber River) conditions. On the other hand, PTV is in closer agreement than LSPIV with benchmark velocities in both experimental settings. In addition, the accuracy of PTV estimations can be directly related to the transit of physical objects in the field of view, thus providing tangible data for uncertainty evaluation.

Single Particle-Inductively Coupled Plasma Mass Spectroscopy Analysis of Metallic Nanoparticles in Environmental Samples with Large Dissolved Analyte Fractions.

PubMed

Schwertfeger, D M; Velicogna, Jessica R; Jesmer, Alexander H; Scroggins, Richard P; Princz, Juliska I

2016-10-18

There is an increasing interest to use single particle-inductively coupled plasma mass spectroscopy (SP-ICPMS) to help quantify exposure to engineered nanoparticles, and their transformation products, released into the environment. Hindering the use of this analytical technique for environmental samples is the presence of high levels of dissolved analyte which impedes resolution of the particle signal from the dissolved. While sample dilution is often necessary to achieve the low analyte concentrations necessary for SP-ICPMS analysis, and to reduce the occurrence of matrix effects on the analyte signal, it is used here to also reduce the dissolved signal relative to the particulate, while maintaining a matrix chemistry that promotes particle stability. We propose a simple, systematic dilution series approach where by the first dilution is used to quantify the dissolved analyte, the second is used to optimize the particle signal, and the third is used as an analytical quality control. Using simple suspensions of well characterized Au and Ag nanoparticles spiked with the dissolved analyte form, as well as suspensions of complex environmental media (i.e., extracts from soils previously contaminated with engineered silver nanoparticles), we show how this dilution series technique improves resolution of the particle signal which in turn improves the accuracy of particle counts, quantification of particulate mass and determination of particle size. The technique proposed here is meant to offer a systematic and reproducible approach to the SP-ICPMS analysis of environmental samples and improve the quality and consistency of data generated from this relatively new analytical tool.

Inertial particle dynamics in large artery flows - Implications for modeling arterial embolisms.

PubMed

Mukherjee, Debanjan; Shadden, Shawn C

2017-02-08

The complexity of inertial particle dynamics through swirling chaotic flow structures characteristic of pulsatile large-artery hemodynamics renders significant challenges in predictive understanding of transport of such particles. This is specifically crucial for arterial embolisms, where knowledge of embolus transport to major vascular beds helps in disease diagnosis and surgical planning. Using a computational framework built upon image-based CFD and discrete particle dynamics modeling, a multi-parameter sampling-based study was conducted on embolic particle dynamics and transport. The results highlighted the strong influence of material properties, embolus size, release instance, and embolus source on embolus distribution to the cerebral, renal and mesenteric, and ilio-femoral vasculature beds. The study also isolated the importance of shear-gradient lift, and elastohydrodynamic contact, in affecting embolic particle transport. Near-wall particle re-suspension due to lift alters aortogenic embolic particle dynamics significantly as compared to cardiogenic. The observations collectively indicated the complex interplay of particle inertia, fluid-particle density ratio, and wall collisions, with chaotic flow structures, which render the overall motion of the particles to be non-trivially dispersive in nature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantifying large-scale historical formation of accommodation in the Mississippi Delta

USGS Publications Warehouse

Morton, Robert A.; Bernier, Julie C.; Kelso, Kyle W.; Barras, John A.

2010-01-01

Large volumes of new accommodation have formed within the Mississippi Delta plain since the mid-1950s in association with rapid conversion of coastal wetlands to open water. The three-dimensional aspects and processes responsible for accommodation formation were quantified by comparing surface elevations, water depths, and vertical displacements of stratigraphic contacts that were correlated between short sediment cores. Integration of data from remotely sensed images, sediment cores, and water-depth surveys at 10 geologically diverse areas in the delta plain provided a basis for estimating the total volume of accommodation formed by interior-wetland subsidence and subsequent erosion. Results indicate that at most of the study areas subsidence was a greater contributor than erosion to the formation of accommodation associated with wetland loss. Tens of millions of cubic meters of accommodation formed rapidly at each of the large open-water bodies that were formerly continuous interior delta-plain marsh. Together the individual study areas account for more than 440 × 106 × m3 of new accommodation that formed as holes in the Mississippi River delta-plain fabric between 1956 and 2004. This large volume provides an estimate of the new sediment that would be needed just at the study areas to restore the delta-plain wetlands to their pre-1956 areal extent and elevations.

Dry deposition of large, airborne particles onto a surrogate surface

NASA Astrophysics Data System (ADS)

Kim, Eugene; Kalman, David; Larson, Timothy

Simultaneous measurements of particle dry deposition flux and airborne number concentration in the open atmosphere were made using three different types of artificially generated particles in the size range 10-100 μm - perlite, diatomaceous earth and glass beads. A combination of gravimetric analysis, automated microscopy and sonic anemometry provided size-resolved estimates of both the inertial and gravitational components of the quasi-laminar layer particle deposition velocity, ( Vd) b, as a function of size. Eddy inertial deposition efficiency ( ηdI) was determined as a function of dimensionless eddy Stokes number (Stk e). In the range 3particles and gases to environmental surfaces. DOE Report PNL-SA-6721, Pacific Northwest Laboratories, Richland, WA), used in several regulatory models, significantly under-predicted (up to seven times) ( Vd) b for large particles ( da>10 μm).

Characterization of diesel particles: effects of fuel reformulation, exhaust aftertreatment, and engine operation on particle carbon composition and volatility.

PubMed

Alander, Timo J A; Leskinen, Ari P; Raunemaa, Taisto M; Rantanen, Leena

2004-05-01

Diesel exhaust particles are the major constituent of urban carbonaceous aerosol being linked to a large range of adverse environmental and health effects. In this work, the effects of fuel reformulation, oxidation catalyst, engine type, and engine operation parameters on diesel particle emission characteristics were investigated. Particle emissions from an indirect injection (IDI) and a direct injection (DI) engine car operating under steady-state conditions with a reformulated low-sulfur, low-aromatic fuel and a standard-grade fuel were analyzed. Organic (OC) and elemental (EC) carbon fractions of the particles were quantified by a thermal-optical transmission analysis method and particle size distributions measured with a scanning mobility particle sizer (SMPS). The particle volatility characteristics were studied with a configuration that consisted of a thermal desorption unit and an SMPS. In addition, the volatility of size-selected particles was determined with a tandem differential mobility analyzer technique. The reformulated fuel was found to produce 10-40% less particulate carbon mass compared to the standard fuel. On the basis of the carbon analysis, the organic carbon contributed 27-61% to the carbon mass of the IDI engine particle emissions, depending on the fuel and engine operation parameters. The fuel reformulation reduced the particulate organic carbon emissions by 10-55%. In the particles of the DI engine, the organic carbon contributed 14-26% to the total carbon emissions, the advanced engine technology, and the oxidation catalyst, thus reducing the OC/EC ratio of particles considerably. A relatively good consistency between the particulate organic fraction quantified with the thermal optical method and the volatile fraction measured with the thermal desorption unit and SMPS was found.

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

DOE PAGES

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; ...

2014-06-27

Data from both laboratory studies and atmospheric measurements are used to develop a simple parametric description for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RH w) are taken to approximate the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterizationmore » developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A correction factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RH w of 105% vs. maximum fractions active at higher RH w. Instrumental factors that affect activation behavior vs. RH w in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this correction factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization to the immersion

Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

DOE PAGES

DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; ...

2015-01-13

Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RH w) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. Themore » parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RH w of 105% vs. maximum fractions active at higher RH w. Instrumental factors that affect activation behavior vs. RH w in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including

Alpha-particle radiotherapy: For large solid tumors diffusion trumps targeting.

PubMed

Zhu, Charles; Sempkowski, Michelle; Holleran, Timothy; Linz, Thomas; Bertalan, Thomas; Josefsson, Anders; Bruchertseifer, Frank; Morgenstern, Alfred; Sofou, Stavroula

2017-06-01

Diffusion limitations on the penetration of nanocarriers in solid tumors hamper their therapeutic use when labeled with α-particle emitters. This is mostly due to the α-particles' relatively short range (≤100 μm) resulting in partial tumor irradiation and limited killing. To utilize the high therapeutic potential of α-particles against solid tumors, we designed non-targeted, non-internalizing nanometer-sized tunable carriers (pH-tunable liposomes) that are triggered to release, within the slightly acidic tumor interstitium, highly-diffusive forms of the encapsulated α-particle generator Actinium-225 ( 225 Ac) resulting in more homogeneous distributions of the α-particle emitters, improving uniformity in tumor irradiation and increasing killing efficacies. On large multicellular spheroids (400 μm-in-diameter), used as surrogates of the avascular areas of solid tumors, interstitially-releasing liposomes resulted in best growth control independent of HER2 expression followed in performance by (a) the HER2-targeting radiolabeled antibody or (b) the non-responsive liposomes. In an orthotopic human HER2-negative mouse model, interstitially-releasing 225 Ac-loaded liposomes resulted in the longest overall and median survival. This study demonstrates the therapeutic potential of a general strategy to bypass the diffusion-limited transport of radionuclide carriers in solid tumors enabling interstitial release from non-internalizing nanocarriers of highly-diffusing and deeper tumor-penetrating molecular forms of α-particle emitters, independent of cell-targeting. Copyright © 2017 Elsevier Ltd. All rights reserved.

Automated 3D trajectory measuring of large numbers of moving particles.

PubMed

Wu, Hai Shan; Zhao, Qi; Zou, Danping; Chen, Yan Qiu

2011-04-11

Complex dynamics of natural particle systems, such as insect swarms, bird flocks, fish schools, has attracted great attention of scientists for years. Measuring 3D trajectory of each individual in a group is vital for quantitative study of their dynamic properties, yet such empirical data is rare mainly due to the challenges of maintaining the identities of large numbers of individuals with similar visual features and frequent occlusions. We here present an automatic and efficient algorithm to track 3D motion trajectories of large numbers of moving particles using two video cameras. Our method solves this problem by formulating it as three linear assignment problems (LAP). For each video sequence, the first LAP obtains 2D tracks of moving targets and is able to maintain target identities in the presence of occlusions; the second one matches the visually similar targets across two views via a novel technique named maximum epipolar co-motion length (MECL), which is not only able to effectively reduce matching ambiguity but also further diminish the influence of frequent occlusions; the last one links 3D track segments into complete trajectories via computing a globally optimal assignment based on temporal and kinematic cues. Experiment results on simulated particle swarms with various particle densities validated the accuracy and robustness of the proposed method. As real-world case, our method successfully acquired 3D flight paths of fruit fly (Drosophila melanogaster) group comprising hundreds of freely flying individuals. © 2011 Optical Society of America

Superficially Porous Particles with 1000 Å Pores for Large Biomolecule High Performance Liquid Chromatography and Polymer Size Exclusion Chromatography

PubMed Central

Wagner, Brian M.; Schuster, Stephanie A.; Boyes, Barry E.; Shields, Taylor J.; Miles, William L.; Haynes, Mark J.; Moran, Robert E.; Kirkland, Joseph J.; Schure, Mark R.

2017-01-01

To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core®, core shell or porous shell) particles with very large (1000 Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications. PMID:28213987

Large eddy simulation modeling of particle-laden flows in complex terrain

NASA Astrophysics Data System (ADS)

Salesky, S.; Giometto, M. G.; Chamecki, M.; Lehning, M.; Parlange, M. B.

2017-12-01

The transport, deposition, and erosion of heavy particles over complex terrain in the atmospheric boundary layer is an important process for hydrology, air quality forecasting, biology, and geomorphology. However, in situ observations can be challenging in complex terrain due to spatial heterogeneity. Furthermore, there is a need to develop numerical tools that can accurately represent the physics of these multiphase flows over complex surfaces. We present a new numerical approach to accurately model the transport and deposition of heavy particles in complex terrain using large eddy simulation (LES). Particle transport is represented through solution of the advection-diffusion equation including terms that represent gravitational settling and inertia. The particle conservation equation is discretized in a cut-cell finite volume framework in order to accurately enforce mass conservation. Simulation results will be validated with experimental data, and numerical considerations required to enforce boundary conditions at the surface will be discussed. Applications will be presented in the context of snow deposition and transport, as well as urban dispersion.

Planck data versus large scale structure: Methods to quantify discordance

NASA Astrophysics Data System (ADS)

Charnock, Tom; Battye, Richard A.; Moss, Adam

2017-06-01

Discordance in the Λ cold dark matter cosmological model can be seen by comparing parameters constrained by cosmic microwave background (CMB) measurements to those inferred by probes of large scale structure. Recent improvements in observations, including final data releases from both Planck and SDSS-III BOSS, as well as improved astrophysical uncertainty analysis of CFHTLenS, allows for an update in the quantification of any tension between large and small scales. This paper is intended, primarily, as a discussion on the quantifications of discordance when comparing the parameter constraints of a model when given two different data sets. We consider Kullback-Leibler divergence, comparison of Bayesian evidences and other statistics which are sensitive to the mean, variance and shape of the distributions. However, as a byproduct, we present an update to the similar analysis in [R. A. Battye, T. Charnock, and A. Moss, Phys. Rev. D 91, 103508 (2015), 10.1103/PhysRevD.91.103508], where we find that, considering new data and treatment of priors, the constraints from the CMB and from a combination of large scale structure (LSS) probes are in greater agreement and any tension only persists to a minor degree. In particular, we find the parameter constraints from the combination of LSS probes which are most discrepant with the Planck 2015 +Pol +BAO parameter distributions can be quantified at a ˜2.55 σ tension using the method introduced in [R. A. Battye, T. Charnock, and A. Moss, Phys. Rev. D 91, 103508 (2015), 10.1103/PhysRevD.91.103508]. If instead we use the distributions constrained by the combination of LSS probes which are in greatest agreement with those from Planck 2015 +Pol +BAO this tension is only 0.76 σ .

Superficially porous particles with 1000Å pores for large biomolecule high performance liquid chromatography and polymer size exclusion chromatography.

PubMed

Wagner, Brian M; Schuster, Stephanie A; Boyes, Barry E; Shields, Taylor J; Miles, William L; Haynes, Mark J; Moran, Robert E; Kirkland, Joseph J; Schure, Mark R

2017-03-17

To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core ® , core shell or porous shell) particles with very large (1000Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Chemical characterization of seven Large Area Collector particles by SXRF. [cosmic dust composition

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Sutton, S. R.

1991-01-01

Optical microscopy and synchrotron X-ray fluorescence (SXRF) are used to analyze the chemical composition of seven dark-appearing cosmic-dust particles obtained in the stratosphere during NASA Johnson Large Area Collector flights. The experimental setup and procedures are outlined, and the results are presented in extensive tables. Three of the particles had abundances similar to those of chondrites (except for low Ca values in one particle); two had a metallic appearance and spectra dominated by Fe and Zn; one contained Cu and Cr plus small amounts of Fe and Zn; and one had igneous-type abundances of minor and trace elements while containing all of the elements seen in chondritic particles, suggesting it may be of extraterrestrial origin.

Large-scale assembly of colloidal particles

NASA Astrophysics Data System (ADS)

Yang, Hongta

increase of the effective refractive index of the diffractive medium, resulting in the red-shift of the optical stop bands. The wavelength shift is linearly proportional to the vapor partial pressure for a spectrum of vapors. Optical simulation and theoretical prediction based on Kelvin equation suggest that a liquid film is formed on the walls of the macropores during vapor condensation. The third topic describes introducing doctor blade coating fabricated large area and low cost macroporous films for thermochromic smart windows, which are useful for energy control in glazed buildings. The fabricated macroporous polymer films exhibit brilliant colors and are capable of reflecting solar radiation when in-situ heated, and become transparent as cavities are filled with a solvent which has the same refractive index as that of the polymer when cooled to building temperature. The fourth topic reports the roll-to roll fabricated excellent water-repelling and self-cleaning macroporous polymer films. The size of the voids can be easily controlled by tuning the duration of an oxygen reactive-ion etching process prior to the removal of the templating silica spheres from silica colloidal-polymer composites. After surface functionalization with fluorosilane, superhydrophobic surface with large apparent water contact angle and small sliding angle can be obtained. The self-cleaning functionality can be achieved on superhydrophobic macroporous coatings by preventing bacterial contamination is further demonstrated. The fifth topic presented is that the template macroporous polymer films with interconnected voids and uniform interconnecting nanopores can be directly used as filtration membranes to achieve size-exclusive separation of particles. The results also demonstrate that more than 85% of small sized particles are recovered after filtration. The results also demonstrate that Escherichia coli can be filtrated by the from macroporous polymer films aqueous solution.

Particle Orbit Analysis in the Finite Beta Plasma of the Large Helical Device using Real Coordinates

NASA Astrophysics Data System (ADS)

Seki, Ryousuke; Matsumoto, Yutaka; Suzuki, Yasuhiro; Watanabe, Kiyomasa; Itagaki, Masafumi

High-energy particles in a finite beta plasma of the Large Helical Device (LHD) are numerically traced in a real coordinate system. We investigate particle orbits by changing the beta value and/or the magnetic field strength. No significant difference is found in the particle orbit classifications between the vacuum magnetic field and the finite beta plasma cases. The deviation of a banana orbit from the flux surfaces strongly depends on the beta value, although the deviation of the orbit of a passing particle is independent of the beta value. In addition, the deviation of the orbit of the passing particle, rather than that of the banana-orbit particles, depends on the magnetic field strength. We also examine the effect of re-entering particles, which repeatedly pass in and out of the last closed flux surface, in the finite beta plasma of the LHD. It is found that the number of re-entering particles in the finite beta plasma is larger than that in the vacuum magnetic field. As a result, the role of reentering particles in the finite beta plasma of the LHD is more important than that in the vacuum magnetic field, and the effect of the charge-exchange reaction on particle confinement in the finite beta plasma is large.

Deep ocean nutrients imply large latitudinal variation in particle transfer efficiency.

PubMed

Weber, Thomas; Cram, Jacob A; Leung, Shirley W; DeVries, Timothy; Deutsch, Curtis

2016-08-02

The "transfer efficiency" of sinking organic particles through the mesopelagic zone and into the deep ocean is a critical determinant of the atmosphere-ocean partition of carbon dioxide (CO2). Our ability to detect large-scale spatial variations in transfer efficiency is limited by the scarcity and uncertainties of particle flux data. Here we reconstruct deep ocean particle fluxes by diagnosing the rate of nutrient accumulation along transport pathways in a data-constrained ocean circulation model. Combined with estimates of organic matter export from the surface, these diagnosed fluxes reveal a global pattern of transfer efficiency to 1,000 m that is high (∼25%) at high latitudes and low (∼5%) in subtropical gyres, with intermediate values in the tropics. This pattern is well correlated with spatial variations in phytoplankton community structure and the export of ballast minerals, which control the size and density of sinking particles. These findings accentuate the importance of high-latitude oceans in sequestering carbon over long timescales, and highlight potential impacts on remineralization depth as phytoplankton communities respond to a warming climate.

Deep ocean nutrients imply large latitudinal variation in particle transfer efficiency

PubMed Central

Weber, Thomas; Cram, Jacob A.; Leung, Shirley W.; DeVries, Timothy; Deutsch, Curtis

2016-01-01

The “transfer efficiency” of sinking organic particles through the mesopelagic zone and into the deep ocean is a critical determinant of the atmosphere−ocean partition of carbon dioxide (CO2). Our ability to detect large-scale spatial variations in transfer efficiency is limited by the scarcity and uncertainties of particle flux data. Here we reconstruct deep ocean particle fluxes by diagnosing the rate of nutrient accumulation along transport pathways in a data-constrained ocean circulation model. Combined with estimates of organic matter export from the surface, these diagnosed fluxes reveal a global pattern of transfer efficiency to 1,000 m that is high (∼25%) at high latitudes and low (∼5%) in subtropical gyres, with intermediate values in the tropics. This pattern is well correlated with spatial variations in phytoplankton community structure and the export of ballast minerals, which control the size and density of sinking particles. These findings accentuate the importance of high-latitude oceans in sequestering carbon over long timescales, and highlight potential impacts on remineralization depth as phytoplankton communities respond to a warming climate. PMID:27457946

Deep ocean nutrients imply large latitudinal variation in particle transfer efficiency

NASA Astrophysics Data System (ADS)

Weber, Thomas; Cram, Jacob A.; Leung, Shirley W.; DeVries, Timothy; Deutsch, Curtis

2016-08-01

The “transfer efficiency” of sinking organic particles through the mesopelagic zone and into the deep ocean is a critical determinant of the atmosphere-ocean partition of carbon dioxide (CO2). Our ability to detect large-scale spatial variations in transfer efficiency is limited by the scarcity and uncertainties of particle flux data. Here we reconstruct deep ocean particle fluxes by diagnosing the rate of nutrient accumulation along transport pathways in a data-constrained ocean circulation model. Combined with estimates of organic matter export from the surface, these diagnosed fluxes reveal a global pattern of transfer efficiency to 1,000 m that is high (˜25%) at high latitudes and low (˜5%) in subtropical gyres, with intermediate values in the tropics. This pattern is well correlated with spatial variations in phytoplankton community structure and the export of ballast minerals, which control the size and density of sinking particles. These findings accentuate the importance of high-latitude oceans in sequestering carbon over long timescales, and highlight potential impacts on remineralization depth as phytoplankton communities respond to a warming climate.

Computation of scattering matrix elements of large and complex shaped absorbing particles with multilevel fast multipole algorithm

NASA Astrophysics Data System (ADS)

Wu, Yueqian; Yang, Minglin; Sheng, Xinqing; Ren, Kuan Fang

2015-05-01

Light scattering properties of absorbing particles, such as the mineral dusts, attract a wide attention due to its importance in geophysical and environment researches. Due to the absorbing effect, light scattering properties of particles with absorption differ from those without absorption. Simple shaped absorbing particles such as spheres and spheroids have been well studied with different methods but little work on large complex shaped particles has been reported. In this paper, the surface Integral Equation (SIE) with Multilevel Fast Multipole Algorithm (MLFMA) is applied to study scattering properties of large non-spherical absorbing particles. SIEs are carefully discretized with piecewise linear basis functions on triangle patches to model whole surface of the particle, hence computation resource needs increase much more slowly with the particle size parameter than the volume discretized methods. To improve further its capability, MLFMA is well parallelized with Message Passing Interface (MPI) on distributed memory computer platform. Without loss of generality, we choose the computation of scattering matrix elements of absorbing dust particles as an example. The comparison of the scattering matrix elements computed by our method and the discrete dipole approximation method (DDA) for an ellipsoid dust particle shows that the precision of our method is very good. The scattering matrix elements of large ellipsoid dusts with different aspect ratios and size parameters are computed. To show the capability of the presented algorithm for complex shaped particles, scattering by asymmetry Chebyshev particle with size parameter larger than 600 of complex refractive index m = 1.555 + 0.004 i and different orientations are studied.

Tuning the bridging attraction between large hard particles by the softness of small microgels.

PubMed

Luo, Junhua; Yuan, Guangcui; Han, Charles C

2016-09-20

In this study, the attraction between large hard polystyrene (PS) spheres is studied by using three types of small microgels as bridging agents. One is a purely soft poly(N-isopropylacrylamide) (PNIPAM) microgel, the other two have a non-deformable PS hard core surrounded by a soft PNIPAM shell but are different in the core-shell ratio. The affinity for bridging the large PS spheres is provided and thus affected by the PNIPAM constituent in the microgels. The bridging effects caused by the microgels can be indirectly incorporated into their influence on the effective attraction interaction between the large hard spheres, since the size of the microgels is very small in comparison to the size of the PS hard spheres. At a given volume fraction of large PS spheres, they behave essentially as hard spheres in the absence of small microgels. By gradually adding the microgels, the large spheres are connected to each other through the bridging of small particles until the attraction strength reaches a maximum value, after which adding more small particles slowly decreases the effective attraction strength and eventually the large particles disperse individually when saturated adsorption is achieved. The aggregation and gelation behaviors triggered by these three types of small microgels are compared and discussed. A way to tune the strength and range of the short-range attractive potential via changing the softness of bridging microgels (which can be achieved either by using core-shell microgels or by changing the temperature) is proposed.

Matrix Dissolution Techniques Applied to Extract and Quantify Precipitates from a Microalloyed Steel

NASA Astrophysics Data System (ADS)

Lu, Junfang; Wiskel, J. Barry; Omotoso, Oladipo; Henein, Hani; Ivey, Douglas G.

2011-07-01

Microalloyed steels possess good strength and toughness, as well as excellent weldability; these attributes are necessary for oil and gas pipelines in northern climates. These properties are attributed in part to the presence of nanosized carbide and carbonitride precipitates. To understand the strengthening mechanisms and to optimize the strengthening effects, it is necessary to quantify the size distribution, volume fraction, and chemical speciation of these precipitates. However, characterization techniques suitable for quantifying fine precipitates are limited because of their fine sizes, wide particle size distributions, and low volume fractions. In this article, two matrix dissolution techniques have been developed to extract precipitates from a Grade100 (yield strength of 690 MPa) microalloyed steel. Relatively large volumes of material can be analyzed, and statistically significant quantities of precipitates of different sizes are collected. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) are combined to analyze the chemical speciation of these precipitates. Rietveld refinement of XRD patterns is used to quantify fully the relative amounts of the precipitates. The size distribution of the nanosized precipitates is quantified using dark-field imaging in the TEM.

Exploring one-particle orbitals in large many-body localized systems

NASA Astrophysics Data System (ADS)

Villalonga, Benjamin; Yu, Xiongjie; Luitz, David J.; Clark, Bryan K.

2018-03-01

Strong disorder in interacting quantum systems can give rise to the phenomenon of many-body localization (MBL), which defies thermalization due to the formation of an extensive number of quasilocal integrals of motion. The one-particle operator content of these integrals of motion is related to the one-particle orbitals (OPOs) of the one-particle density matrix and shows a strong signature across the MBL transition as recently pointed out by Bera et al. [Phys. Rev. Lett. 115, 046603 (2015), 10.1103/PhysRevLett.115.046603; Ann. Phys. 529, 1600356 (2017), 10.1002/andp.201600356]. We study the properties of the OPOs of many-body eigenstates of an MBL system in one dimension. Using shift-and-invert MPS, a matrix product state method to target highly excited many-body eigenstates introduced previously [Phys. Rev. Lett. 118, 017201 (2017), 10.1103/PhysRevLett.118.017201], we are able to obtain accurate results for large systems of sizes up to L =64 . We find that the OPOs drawn from eigenstates at different energy densities have high overlap and their occupations are correlated with the energy of the eigenstates. Moreover, the standard deviation of the inverse participation ratio of these orbitals is maximal at the nose of the mobility edge. Also, the OPOs decay exponentially in real space, with a correlation length that increases at low disorder. In addition, we find that the probability distribution of the strength of the large-range coupling constants of the number operators generated by the OPOs approach a log-uniform distribution at strong disorder.

Large-scale tomographic particle image velocimetry using helium-filled soap bubbles

NASA Astrophysics Data System (ADS)

Kühn, Matthias; Ehrenfried, Klaus; Bosbach, Johannes; Wagner, Claus

2011-04-01

To measure large-scale flow structures in air, a tomographic particle image velocimetry (tomographic PIV) system for measurement volumes of the order of one cubic metre is developed, which employs helium-filled soap bubbles (HFSBs) as tracer particles. The technique has several specific characteristics compared to most conventional tomographic PIV systems, which are usually applied to small measurement volumes. One of them is spot lights on the HFSB tracers, which slightly change their position, when the direction of observation is altered. Further issues are the large particle to voxel ratio and the short focal length of the used camera lenses, which result in a noticeable variation of the magnification factor in volume depth direction. Taking the specific characteristics of the HFSBs into account, the feasibility of our large-scale tomographic PIV system is demonstrated by showing that the calibration errors can be reduced down to 0.1 pixels as required. Further, an accurate and fast implementation of the multiplicative algebraic reconstruction technique, which calculates the weighting coefficients when needed instead of storing them, is discussed. The tomographic PIV system is applied to measure forced convection in a convection cell at a Reynolds number of 530 based on the inlet channel height and the mean inlet velocity. The size of the measurement volume and the interrogation volumes amount to 750 mm × 450 mm × 165 mm and 48 mm × 48 mm × 24 mm, respectively. Validation of the tomographic PIV technique employing HFSBs is further provided by comparing profiles of the mean velocity and of the root mean square velocity fluctuations to respective planar PIV data.

Using large volume samplers for the monitoring of particle bound micro pollutants in rivers

NASA Astrophysics Data System (ADS)

Kittlaus, Steffen; Fuchs, Stephan

2015-04-01

relatively low cost approach (less costs for analysis because of small sample number) allows to quantify the pollutant load, to derive dissolved-solid partition coefficients and to quantify the pollutant load in different particle size classes.

Progress Towards Identifying and Quantifying the Organic Ice Nucleating Particles in Soils and Aerosols

NASA Astrophysics Data System (ADS)

Hill, T. C. J.; DeMott, P. J.; Fröhlich-Nowoisky, J.; Tobo, Y.; Suski, K. J.; Levin, E. J.; Kreidenweis, S. M.; Franc, G. D.

2014-12-01

Soil and plant surfaces emit ice nucleating particles (INP) to the atmosphere, especially when disturbed by wind, harvesting, rain or fire. Organic (biogenic) INP are abundant in most soils and dominate the population that nucleate >-15°C. For example, the sandy topsoil of sagebrush shrubland, a widespread ecotype prone to wind erosion after fire, contains ~106 organic INP g-1 at -6°C. The relevance of organic INP may also extend to colder temperatures than previously thought: Particles of soil organic matter (SOM) have been shown to be more important than mineral particles for the ice nucleating ability of agricultural soil dusts to -34°C. While the abundance of ice nucleation active (INA) bacteria on plants has been established, the identity of the organic INP in and emitted by soils remains a 40-year-old mystery. The need to understand their production and release is highlighted by recent findings that INA bacteria (measured with qPCR) account for few, if any, of the warm-temperature organic INP that predominate in boundary layer aerosols and snow; organic INP lofted with soil dusts seem a likely source. The complexity of SOM hinders its investigation. It contains decomposing plant materials, a diverse microbial and microfaunal community, humus, and inert organic matter. All are biochemically complex and all may contain ice nucleating constituents, either by design or by chance. Indeed the smoothness of the INP temperature spectra of soils is indicative of numerous, overlapping distributions of INP. We report recent progress in identifying and quantifying the organic INP in soils and boundary layer aerosols representative of West Central U.S. ecosystems, and how their characteristics may affect their dispersal. Chemical, enzymatic and DNA-based tests were used to assess contributions of INP from plant tissues, INA bacteria, INA fungi, organic crystals, monolayers of aliphatic alcohols, carbohydrates, and humic substances, while heat- and peroxide-based tests

Development of Detonation Flame Sprayed Cu-Base Coatings Containing Large Ceramic Particles

NASA Astrophysics Data System (ADS)

Tillmann, Wolfgang; Vogli, Evelina; Nebel, Jan

2007-12-01

Metal-matrix composites (MMCs) containing large ceramic particles as superabrasives are typically used for grinding stone, minerals, and concrete. Sintering and brazing are the key manufacturing technologies for grinding tool production. However, restricted geometry flexibility and the absence of repair possibilities for damaged tool surfaces, as well as difficulties of controlling material interfaces, are the main weaknesses of these production processes. Thermal spraying offers the possibility to avoid these restrictions. The research for this paper investigated a fabrication method based on the use of detonation flame spraying technology to bond large superabrasive particles (150-600 μm, needed for grinding minerals and stones) in a metallic matrix. Layer morphology and bonding quality are evaluated with respect to superabrasive material, geometry, spraying, and powder-injection parameters. The influence of process temperature and the possibilities of thermal treatment of MMC layers are analyzed.

Multiscale virtual particle based elastic network model (MVP-ENM) for normal mode analysis of large-sized biomolecules.

PubMed

Xia, Kelin

2017-12-20

In this paper, a multiscale virtual particle based elastic network model (MVP-ENM) is proposed for the normal mode analysis of large-sized biomolecules. The multiscale virtual particle (MVP) model is proposed for the discretization of biomolecular density data. With this model, large-sized biomolecular structures can be coarse-grained into virtual particles such that a balance between model accuracy and computational cost can be achieved. An elastic network is constructed by assuming "connections" between virtual particles. The connection is described by a special harmonic potential function, which considers the influence from both the mass distributions and distance relations of the virtual particles. Two independent models, i.e., the multiscale virtual particle based Gaussian network model (MVP-GNM) and the multiscale virtual particle based anisotropic network model (MVP-ANM), are proposed. It has been found that in the Debye-Waller factor (B-factor) prediction, the results from our MVP-GNM with a high resolution are as good as the ones from GNM. Even with low resolutions, our MVP-GNM can still capture the global behavior of the B-factor very well with mismatches predominantly from the regions with large B-factor values. Further, it has been demonstrated that the low-frequency eigenmodes from our MVP-ANM are highly consistent with the ones from ANM even with very low resolutions and a coarse grid. Finally, the great advantage of MVP-ANM model for large-sized biomolecules has been demonstrated by using two poliovirus virus structures. The paper ends with a conclusion.

A Large and Intact Viral Particle Penetrates the Endoplasmic Reticulum Membrane to Reach the Cytosol

PubMed Central

Inoue, Takamasa; Tsai, Billy

2011-01-01

Non-enveloped viruses penetrate host membranes to infect cells. A cell-based assay was used to probe the endoplasmic reticulum (ER)-to-cytosol membrane transport of the non-enveloped SV40. We found that, upon ER arrival, SV40 is released into the lumen and undergoes sequential disulfide bond disruptions to reach the cytosol. However, despite these ER-dependent conformational changes, SV40 crosses the ER membrane as a large and intact particle consisting of the VP1 coat, the internal components VP2, VP3, and the genome. This large particle subsequently disassembles in the cytosol. Mutant virus and inhibitor studies demonstrate VP3 and likely the viral genome, as well as cellular proteasome, control ER-to-cytosol transport. Our results identify the sequence of events, as well as virus and host components, that regulate ER membrane penetration. They also suggest that the ER membrane supports passage of a large particle, potentially through either a sizeable protein-conducting channel or the lipid bilayer. PMID:21589906

Cell and Particle Interactions and Aggregation During Electrophoretic Motion

NASA Technical Reports Server (NTRS)

Davis, Robert H.

2000-01-01

The objectives of this research were (i) to perform experiments for observing and quantifying electrophoretic aggregation, (ii) to develop a theoretical description to appropriately analyze and compare with the experimental results, (iii) to study the combined effects of electrophoretic and gravitational aggregation of large particles, and the combined effects of electrophoretic and Brownian aggregation of small particles, and (iv) to perform a preliminary design of a potential future flight experiment involving electrophoretic aggregation. Electrophoresis refers to the motion of charged particles, droplets or molecules in response to an applied electric field. Electrophoresis is commonly used for analysis and separation of biological particles or molecules. When particles have different surface charge densities or potentials, they will migrate at different velocities in an electric field. This differential migration leads to the possibility that they will collide and aggregate, thereby preventing separation.

Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary: Application of hydrodynamic and particle tracking models

USGS Publications Warehouse

Defne, Zafer; Ganju, Neil K.

2015-01-01

Estuarine residence time is a major driver of eutrophication and water quality. Barnegat Bay-Little Egg Harbor (BB-LEH), New Jersey, is a lagoonal back-barrier estuary that is subject to anthropogenic pressures including nutrient loading, eutrophication, and subsequent declines in water quality. A combination of hydrodynamic and particle tracking modeling was used to identify the mechanisms controlling flushing, residence time, and spatial variability of particle retention. The models demonstrated a pronounced northward subtidal flow from Little Egg Inlet in the south to Pt. Pleasant Canal in the north due to frictional effects in the inlets, leading to better flushing of the southern half of the estuary and particle retention in the northern estuary. Mean residence time for BB-LEH was 13 days but spatial variability was between ∼0 and 30 days depending on the initial particle location. Mean residence time with tidal forcing alone was 24 days (spatial variability between ∼0 and 50 days); the tides were relatively inefficient in flushing the northern end of the Bay. Scenarios with successive exclusion of physical processes from the models revealed that meteorological and remote offshore forcing were stronger drivers of exchange than riverine inflow. Investigations of water quality and eutrophication should take into account spatial variability in hydrodynamics and residence time in order to better quantify the roles of nutrient loading, production, and flushing.

Wear rate quantifying in real-time using the charged particle surface activation

NASA Astrophysics Data System (ADS)

Alexandreanu, B.; Popa-Simil, L.; Voiculescu, D.; Racolta, P. M.

1997-02-01

Surface activation, commonly known as Thin Layer Activation (TLA), is currently employed in over 30 accelerator laboratories around the world for wear and/or corrosion monitoring in industrial plants [1-6]. TLA was primarily designed and developed to meet requirements of potential industrial partners, in order to transfer this technique from research to industry. The method consists of accelerated ion bombardment of a surface of interest, e.g., a machine part subjected to wear. Loss of material owing to wear, erosive corrosion or abrasion is characterized by monitoring the resultant changes in radioactivity. In principle, depending upon the case at hand, one may choose to measure either the remnant activity of the component of interest or to monitor the activity of the debris. For applications of the second type, especially when a lubricating agent is involved, dedicated installations have been constructed and adapted to an engine or a tribological testing stand in order to assure oil circulation around an externally placed detection gauge. This way, the wear particles suspended in the lubricant can be detected and the material loss rates quantified in real time. Moreover, in specific cases, such as the one presented in this paper, remnant activity measurements prove to be useful tools for complementary results. This paper provides a detailed presentation of such a case: in situ resistance-to-wear testing of two types of piston rings.

New image analysis of large food particles can discriminate experimentally suppressed mastication.

PubMed

Sugimoto, K; Iegami, C M; Iida, S; Naito, M; Tamaki, R; Minagi, S

2012-06-01

Objective parameters that could provide a basis for food texture selection for elderly or dysphagic patients have not been established. We, therefore, aimed to develop a precise method of measuring large particles (>2 mm in diameter) in a bolus and an analytical method to provide a scientific rationale for food selection under masticatory dysfunction conditions. We developed a new illumination system to evaluate the ability of twenty female participants (mean age, 23·4 ± 4·3 years) to masticate carrots, peanuts and beef with full, half and one quarter of the number of masticatory strokes. We also evaluated mastication under suppressed force, regulated by 20% electromyographic of the masseter muscle. The intercept and inclination of the regression line for the distribution of large particles were adopted as coefficients for the discrimination of masticatory efficiency. Single set of coefficient thresholds of 0·10 for the intercept and 1·62 for the inclination showed excellent discrimination of masticatory conditions for all three test foods with high specificity and sensitivity. These results suggested that our method of analysing the distribution of particles >2 mm in diameter might provide the basis for the appropriate selection of food texture for masticatory dysfunction patients from the standpoint of comminution. © 2012 Blackwell Publishing Ltd.

Quantification of inhaled aerosol particles composed of toxic household disinfectant using radioanalytical method.

PubMed

Shim, Ha Eun; Lee, Jae Young; Lee, Chang Heon; Mushtaq, Sajid; Song, Ha Yeon; Song, Lee; Choi, Seong-Jin; Lee, Kyuhong; Jeon, Jongho

2018-05-25

To assess the risk posed by a toxic chemical to human health, it is essential to quantify its uptake in a living subject. This study aims to investigate the biological distribution of inhaled polyhexamethylene guanidine (PHMG) aerosol particle, which is known to cause severe pulmonary damage. By labeling with indium-111 ( 111 In), we quantified the uptake of PHMG for up to 7 days after inhalation exposure in rats. The data demonstrate that PHMG is only slowly cleared, with approximately 74% of inhaled particles persisting in the lungs after 168 h. Approximately 5.3% of inhaled particles were also translocated to the liver after 168 h, although the level of redistribution to other tissues, including the kidneys and spleen, was minimal. These observations suggest that large uptake and slow clearance may underlie the fatal inhalation toxicity of PHMG in humans. Copyright © 2018 Elsevier Ltd. All rights reserved.

Smoothed particle hydrodynamics method from a large eddy simulation perspective

NASA Astrophysics Data System (ADS)

Di Mascio, A.; Antuono, M.; Colagrossi, A.; Marrone, S.

2017-03-01

The Smoothed Particle Hydrodynamics (SPH) method, often used for the modelling of the Navier-Stokes equations by a meshless Lagrangian approach, is revisited from the point of view of Large Eddy Simulation (LES). To this aim, the LES filtering procedure is recast in a Lagrangian framework by defining a filter that moves with the positions of the fluid particles at the filtered velocity. It is shown that the SPH smoothing procedure can be reinterpreted as a sort of LES Lagrangian filtering, and that, besides the terms coming from the LES convolution, additional contributions (never accounted for in the SPH literature) appear in the equations when formulated in a filtered fashion. Appropriate closure formulas are derived for the additional terms and a preliminary numerical test is provided to show the main features of the proposed LES-SPH model.

The small dense LDL particle/large buoyant LDL particle ratio is associated with glucose metabolic status in pregnancy.

PubMed

Chen, Yanmin; Du, Mengkai; Xu, Jianyun; Chen, Danqing

2017-12-14

The lipoprotein subfraction particle profile can be used to improve clinical assessments of cardiovascular disease risk and contribute to early detection of atherogenic dyslipidemia. Lipid alterations in gestational diabetes have been extensively studied, but the results have been inconsistent. Here, we investigated serum lipoprotein subfraction particle levels and their association with glucose metabolic status in pregnancy. Twenty-eight pregnant women with gestational diabetes and 56 pregnant women with normal glucose tolerance matched for body mass index were enrolled in this study. We assessed fasting serum lipid concentrations and lipoprotein subfraction particle levels in participants between 24 and 28 weeks of gestation. The level of low-density lipoprotein (LDL) cholesterol was significantly lower in women with gestational diabetes than in those with normal glucose tolerance, but the triglyceride and high-density lipoprotein (HDL) cholesterol levels of the two groups were similar. Lipoprotein particle analysis showed that very-low-density lipoprotein (VLDL) particle number and the small dense LDL particle/large buoyant LDL particle (sdLDL-P/lbLDL-P) ratio were significantly higher in women with gestational diabetes than in those with normal glucose tolerance (P = 0.013 and P = 0.015, respectively). In multivariate analysis, fasting glucose was independently and positively associated with sdLDL-P/lbLDL-P ratio even after adjustment for maternal age, gestational weight gain, BMI and LDL cholesterol (standardized Beta = 0.214, P = 0.029). The sdLDL-P/lbLDL-P ratio is higher in GDM compared with non-diabetic pregnant women, and positively and independently associated with fasting glucose in pregnant women.

Trajectory Studies of Large HNO3-Containing PSC Particles in the Arctic: Evidence for the Role of NAT

NASA Technical Reports Server (NTRS)

McKinney, K. A.; Wennberg, P. O.; Dhaniyala, S.; Fahey, D. W.; Northway, M. J.; Kuenzi, K. F.; Kleinboehl, A.; Sinnhuber, M.; Kuellmann, H.; Bremer, H.;

Catalytic Metal Free Production of Large Cage Structure Carbon Particles: A Candidate for Hydrogen Storage

NASA Technical Reports Server (NTRS)

Kimura, Yuki; Nuth, Joseph A., III; Ferguson, Frank T.

2005-01-01

We will demonstrate that carbon particles consisting of large cages can be produced without catalytic metal. The carbon particles were produced in CO gas as well as by introduction of 5% methane gas into the CO gas. The gas-produced carbon particles were able to absorb approximately 16.2 wt% of hydrogen. This value is 2.5 times higher than the 6.5 wt% goal for the vehicular hydrogen storage proposed by the Department of Energy in the USA. Therefore, we believe that this carbon particle is an excellent candidate for hydrogen storage for fuel cells.

Spatial Variability of Sources and Mixing State of Atmospheric Particles in a Metropolitan Area.

PubMed

Ye, Qing; Gu, Peishi; Li, Hugh Z; Robinson, Ellis S; Lipsky, Eric; Kaltsonoudis, Christos; Lee, Alex K Y; Apte, Joshua S; Robinson, Allen L; Sullivan, Ryan C; Presto, Albert A; Donahue, Neil M

2018-05-30

Characterizing intracity variations of atmospheric particulate matter has mostly relied on fixed-site monitoring and quantifying variability in terms of different bulk aerosol species. In this study, we performed ground-based mobile measurements using a single-particle mass spectrometer to study spatial patterns of source-specific particles and the evolution of particle mixing state in 21 areas in the metropolitan area of Pittsburgh, PA. We selected sampling areas based on traffic density and restaurant density with each area ranging from 0.2 to 2 km 2 . Organics dominate particle composition in all of the areas we sampled while the sources of organics differ. The contribution of particles from traffic and restaurant cooking varies greatly on the neighborhood scale. We also investigate how primary and aged components in particles mix across the urban scale. Lastly we quantify and map the particle mixing state for all areas we sampled and discuss the overall pattern of mixing state evolution and its implications. We find that in the upwind and downwind of the urban areas, particles are more internally mixed while in the city center, particle mixing state shows large spatial heterogeneity that is mostly driven by emissions. This study is to our knowledge, the first study to perform fine spatial scale mapping of particle mixing state using ground-based mobile measurement and single-particle mass spectrometry.

Lagrangian velocity and acceleration correlations of large inertial particles in a closed turbulent flow

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

Machicoane, Nathanaël; Volk, Romain

We investigate the response of large inertial particle to turbulent fluctuations in an inhomogeneous and anisotropic flow. We conduct a Lagrangian study using particles both heavier and lighter than the surrounding fluid, and whose diameters are comparable to the flow integral scale. Both velocity and acceleration correlation functions are analyzed to compute the Lagrangian integral time and the acceleration time scale of such particles. The knowledge of how size and density affect these time scales is crucial in understanding particle dynamics and may permit stochastic process modelization using two-time models (for instance, Sawford’s). As particles are tracked over long timesmore » in the quasi-totality of a closed flow, the mean flow influences their behaviour and also biases the velocity time statistics, in particular the velocity correlation functions. By using a method that allows for the computation of turbulent velocity trajectories, we can obtain unbiased Lagrangian integral time. This is particularly useful in accessing the scale separation for such particles and to comparing it to the case of fluid particles in a similar configuration.« less

Particle physics and polyedra proximity calculation for hazard simulations in large-scale industrial plants

NASA Astrophysics Data System (ADS)

Plebe, Alice; Grasso, Giorgio

2016-12-01

This paper describes a system developed for the simulation of flames inside an open-source 3D computer graphic software, Blender, with the aim of analyzing in virtual reality scenarios of hazards in large-scale industrial plants. The advantages of Blender are of rendering at high resolution the very complex structure of large industrial plants, and of embedding a physical engine based on smoothed particle hydrodynamics. This particle system is used to evolve a simulated fire. The interaction of this fire with the components of the plant is computed using polyhedron separation distance, adopting a Voronoi-based strategy that optimizes the number of feature distance computations. Results on a real oil and gas refining industry are presented.

Toward particle-level filtering of individual collision events at the Large Hadron Collider and beyond

NASA Astrophysics Data System (ADS)

Colecchia, Federico

2014-03-01

Low-energy strong interactions are a major source of background at hadron colliders, and methods of subtracting the associated energy flow are well established in the field. Traditional approaches treat the contamination as diffuse, and estimate background energy levels either by averaging over large data sets or by restricting to given kinematic regions inside individual collision events. On the other hand, more recent techniques take into account the discrete nature of background, most notably by exploiting the presence of substructure inside hard jets, i.e. inside collections of particles originating from scattered hard quarks and gluons. However, none of the existing methods subtract background at the level of individual particles inside events. We illustrate the use of an algorithm that will allow particle-by-particle background discrimination at the Large Hadron Collider, and we envisage this as the basis for a novel event filtering procedure upstream of the official reconstruction chains. Our hope is that this new technique will improve physics analysis when used in combination with state-of-the-art algorithms in high-luminosity hadron collider environments.

Precision sizing of moving large particles using diffraction splitting of Doppler lines

NASA Astrophysics Data System (ADS)

Kononenko, Vadim L.

1999-02-01

It is shown, that the Doppler line from a single large particle moving with a constant velocity through a finite- width laser beam, undergoes a doublet-type splitting under specific observation conditions. A general requirement is that particle size 2a is not negligibly small, compared with beam diameter 2w$0. Three optical mechanisms of line splitting are considered. The first one is based on nonsymmetric diffraction of a bounded laser beam by a moving particle. The second arises from the transient geometry of diffraction. The third mechanism, of photometric nature, originates from specific time variation of total illuminance of moving particles when 2a>Lambda, the interference fringe spacing in the measuring volume. The diffraction splitting is observed when a detector is placed near one of diffraction minima corresponding to either of probing beams, and 2a equals (n0.5)Lambda for n equals 1,2. The photometric splitting is observed with an image-forming optics, when 2a equals n(Lambda) . That gives the possibility of distant particles sizing based on the Doppler line splitting phenomenon. A general theory of line splitting is developed, and used to explain the experimental observations quantitatively. The influence of the scattering angels and observation angle on the line splitting characteristics is studied analytically and numerically.

Lunar Regolith Particle Shape Analysis

NASA Technical Reports Server (NTRS)

Kiekhaefer, Rebecca; Hardy, Sandra; Rickman, Douglas; Edmunson, Jennifer

2013-01-01

Future engineering of structures and equipment on the lunar surface requires significant understanding of particle characteristics of the lunar regolith. Nearly all sediment characteristics are influenced by particle shape; therefore a method of quantifying particle shape is useful both in lunar and terrestrial applications. We have created a method to quantify particle shape, specifically for lunar regolith, using image processing. Photomicrographs of thin sections of lunar core material were obtained under reflected light. Three photomicrographs were analyzed using ImageJ and MATLAB. From the image analysis measurements for area, perimeter, Feret diameter, orthogonal Feret diameter, Heywood factor, aspect ratio, sieve diameter, and sieve number were recorded. Probability distribution functions were created from the measurements of Heywood factor and aspect ratio.

Trapping and patterning of large particles and cells in a 1D ultrasonic standing wave.

PubMed

Habibi, Ruhollah; Devendran, Citsabehsan; Neild, Adrian

2017-09-26

The use of ultrasound for trapping and patterning particles or cells in microfluidic systems is usually confined to particles which are considerably smaller than the acoustic wavelength. In this regime, the primary forces result in particle clustering at certain locations in the sound field, whilst secondary forces, those arising due to particle-particle interaction forces, assist this clustering process. Using a wavelength closer to the size of the particles allows one particle to be held at each primary force minimum. However, to achieve this, the influence of secondary forces needs to be carefully studied, as inter-particle attraction is highly undesirable. Here, we study the effect of particle size and material properties on both the primary and secondary acoustic forces as the particle diameter is increased towards the wavelength of the 1-dimensional axisymmetric ultrasonic field. We show that the resonance frequencies of the solid sphere have an important role in the resulting secondary forces which leads to a narrow band of frequencies that allow the patterning of large particles in a 1-D array. Knowledge regarding the naturally existent secondary forces would allow for system designs enabling single cell studies to be conducted in a biologically safe manner.

Large Proton Anisotropies in the 18 August 2010 Solar Particle Event

NASA Technical Reports Server (NTRS)

Leske, R. A.; Cohen, C. M. S.; Mewaldt, R. A.; Christian, Eric R.; Cummings, A. C.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, Mark E.; Rosenvinge, Tycho T Von

2012-01-01

The solar particle event observed at STEREO Ahead on 18 August 2010 displayeda rich variety of behavior in the particle anisotropies. Sectored rates measured by theLow Energy Telescope (LET) on STEREO showed very large bidirectional anisotropies in4 6 MeV protons for the first 17 hours of the event while inside a magnetic cloud, withintensities along the field direction several hundred to nearly 1000 times greater than thoseperpendicular to the field. At the trailing end of the cloud, the protons became isotropic andtheir spectrum hardened slightly, while the HeH abundance ratio plunged by a factor of approximatelyfour for about four hours. Associated with the arrival of a shock on 20 Augustwas a series of brief (10 minute duration) intensity increases (commonly called shockspikes) with relatively narrow angular distributions (45 FWHM), followed by an abruptdecrease in particle intensities at the shock itself and a reversal of the proton flow to a directiontoward the Sun and away from the receding shock. We discuss the STEREOLETobservations of this interesting event in the context of other observations reported in theliterature

Recent advances quantifying the large wood dynamics in river basins: New methods and remaining challenges

NASA Astrophysics Data System (ADS)

Ruiz-Villanueva, Virginia; Piégay, Hervé; Gurnell, Angela A.; Marston, Richard A.; Stoffel, Markus

2016-09-01

Large wood is an important physical component of woodland rivers and significantly influences river morphology. It is also a key component of stream ecosystems. However, large wood is also a source of risk for human activities as it may damage infrastructure, block river channels, and induce flooding. Therefore, the analysis and quantification of large wood and its mobility are crucial for understanding and managing wood in rivers. As the amount of large-wood-related studies by researchers, river managers, and stakeholders increases, documentation of commonly used and newly available techniques and their effectiveness has also become increasingly relevant as well. Important data and knowledge have been obtained from the application of very different approaches and have generated a significant body of valuable information representative of different environments. This review brings a comprehensive qualitative and quantitative summary of recent advances regarding the different processes involved in large wood dynamics in fluvial systems including wood budgeting and wood mechanics. First, some key definitions and concepts are introduced. Second, advances in quantifying large wood dynamics are reviewed; in particular, how measurements and modeling can be combined to integrate our understanding of how large wood moves through and is retained within river systems. Throughout, we present a quantitative and integrated meta-analysis compiled from different studies and geographical regions. Finally, we conclude by highlighting areas of particular research importance and their likely future trajectories, and we consider a particularly underresearched area so as to stress the future challenges for large wood research.

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

Quality evaluation of radiographic contrast media in large-volume prefilled syringes and vials.

PubMed

Sendo, T; Hirakawa, M; Yaginuma, M; Aoyama, T; Oishi, R

1998-06-01

The authors compared the particle contaminations of radiographic contrast media packaged in large-volume prefilled syringes and vials. Particle counting was performed for four contrast media packaged in large-volume prefilled syringes (iohexol, ioversol, ioversol for angiography, and ioxaglate) and three contrast media packaged in vials (iohexol, ioversol, and ioxaglate). X-ray emission spectrometry was performed to characterize the individual particles. The amount of silicone oil in the syringe was quantified with infrared spectrophotometry. The particle contamination in syringes containing ioversol was higher than that in syringes containing iohexol or ioxaglate. Particle contamination in the vials was relatively low, except with ioxaglate. X-ray emission spectrometry of the components of the syringe and vial showed that the source of particles was internal material released from the rubber stopper or inner surface. The particle counts for contrast media packaged in syringes and vials varied considerably among the different contrast media and were related to the amount of silicone oil on the inner surface and rubber piston of the syringe.

Comparison of on-line and off-line methods to quantify reactive oxygen species (ROS) in atmospheric aerosols

NASA Astrophysics Data System (ADS)

Fuller, S. J.; Wragg, F. P. H.; Nutter, J.; Kalberer, M.

2014-08-01

Atmospheric aerosol particle concentrations have been linked with a wide range of pulmonary and cardio-vascular diseases but the particle properties responsible for these negative health effects are largely unknown. It is often speculated that reactive oxygen species (ROS) present in atmospheric particles lead to oxidative stress in, and ultimately disease of, the human lung. The quantification of ROS is highly challenging because some ROS components such as radicals are highly reactive and therefore short-lived. Thus, fast analysis methods are likely advantageous over methods with a long delay between aerosol sampling and ROS analysis. We present for the first time a detailed comparison of conventional off-line and fast on-line methods to quantify ROS in organic aerosols. For this comparison a new and fast on-line instrument was built and characterized to quantify ROS in aerosol particles with high sensitivity and a limit of detection of 4 nmol H2O2 equivalents per m3 air. ROS concentrations are measured with a time resolution of approximately 15 min, which allows the tracking of fast changing atmospheric conditions. The comparison of the off-line and on-line method shows that, in oxidized organic model aerosol particles, the majority of ROS have a very short lifetime of a few minutes whereas a small fraction is stable for a day or longer. This indicates that off-line techniques, where there is often a delay of hours to days between particle collection and ROS analysis, may severely underestimate true ROS concentrations and that fast on-line techniques are necessary for a reliable ROS quantification in atmospheric aerosol particles and a meaningful correlation with health outcomes.

Partition resampling and extrapolation averaging: approximation methods for quantifying gene expression in large numbers of short oligonucleotide arrays.

PubMed

Goldstein, Darlene R

2006-10-01

Studies of gene expression using high-density short oligonucleotide arrays have become a standard in a variety of biological contexts. Of the expression measures that have been proposed to quantify expression in these arrays, multi-chip-based measures have been shown to perform well. As gene expression studies increase in size, however, utilizing multi-chip expression measures is more challenging in terms of computing memory requirements and time. A strategic alternative to exact multi-chip quantification on a full large chip set is to approximate expression values based on subsets of chips. This paper introduces an extrapolation method, Extrapolation Averaging (EA), and a resampling method, Partition Resampling (PR), to approximate expression in large studies. An examination of properties indicates that subset-based methods can perform well compared with exact expression quantification. The focus is on short oligonucleotide chips, but the same ideas apply equally well to any array type for which expression is quantified using an entire set of arrays, rather than for only a single array at a time. Software implementing Partition Resampling and Extrapolation Averaging is under development as an R package for the BioConductor project.

Quantifying hyporheic exchange dynamics in a highly regulated large river reach

NASA Astrophysics Data System (ADS)

Zhou, T.; Bao, J.; Huang, M.; Hou, Z.; Arntzen, E.; Mackley, R.; Harding, S.; Crump, A.; Xu, Y.; Song, X.; Chen, X.; Stegen, J.; Hammond, G. E.; Thorne, P. D.; Zachara, J. M.

2016-12-01

Hyporheic exchange is an important mechanism taking place in riverbanks and riverbed sediments, where the river water and shallow groundwater mix and interact with each other. The direction and magnitude of hyporheic flux that penetrates the river bed and residence time of river water in the hyporheic zone are critical for biogeochemical processes such as carbon and nitrogen cycling, and biodegradation of organic contaminants. Hyporheic flux can be quantified using many direct and indirect measurements as well as analytical and numerical modeling tools. However, in a relatively large river, these methods can be limited by the accessibility, spatial constraints, complexity of geomorphologic features and subsurface properties, and computational power. In rivers regulated by hydroelectric dams, quantifying hyporheic fluxes becomes more challenging due to frequent hydropeaking events created by dam operations. In this study, we developed and validated methods that combined field measurements and numerical modeling for estimating hyporheic fluxes across the river bed in a 7-km long reach of the highly regulated Columbia River. The reach has a minimum width of about 800 meters and variations in river stage within a day could be up to two meters due to the upstream dam operations. In shallow water along the shoreline, vertical thermal profiles measured by self-recording thermistors were combined with time series of hydraulic gradient derived from river stage and water level at in-land wells to estimate the hyporheic flux rate. For the deep section, a high resolution computational fluid dynamics (CFD) modeling framework was developed to characterize the spatial distribution of flux rates at the river bed and the residence time of hyporheic flow at different river flow conditions. Our modeling results show that the rates of hyporheic exchange and residence time are controlled by (1) hydrostatic pressure induced by river stage fluctuations, and (2) hydrodynamic drivers

Large-x connections of nuclear and high-energy physics

DOE PAGES

Accardi, Alberto

2013-11-20

I discuss how global QCD fits of parton distribution functions can make the somewhat separated fields of high-energy particle physics and lower energy hadronic and nuclear physics interact to the benefit of both. I review specific examples of this interplay from recent works of the CTEQ-Jefferson Lab collaboration, including hadron structure at large parton momentum and gauge boson production at colliders. Particular attention is devoted to quantifying theoretical uncertainties arising in the treatment of large partonic momentum contributions to deep inelastic scattering observables, and to discussing the experimental progress needed to reduce these.

Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

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

Bewerunge, Jörg; Capellmann, Ronja F.; Platten, Florian

2016-07-28

Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g{sup (1)}(r) and an analogue of the Edwards-Anderson order parameter g{sup (2)}(r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

Test-particle simulations of SEP propagation in IMF with large-scale fluctuations

NASA Astrophysics Data System (ADS)

Kelly, J.; Dalla, S.; Laitinen, T.

2012-11-01

The results of full-orbit test-particle simulations of SEPs propagating through an IMF which exhibits large-scale fluctuations are presented. A variety of propagation conditions are simulated - scatter-free, and scattering with mean free path, λ, of 0.3 and 2.0 AU - and the cross-field transport of SEPs is investigated. When calculating cross-field displacements the Parker spiral geometry is accounted for and the role of magnetic field expansion is taken into account. It is found that transport across the magnetic field is enhanced in the λ =0.3 AU and λ =2 AU cases, compared to the scatter-free case, with the λ =2 AU case in particular containing outlying particles that had strayed a large distance across the IMF. Outliers are catergorized by means of Chauvenet's criterion and it is found that typically between 1 and 2% of the population falls within this category. The ratio of latitudinal to longitudinal diffusion coefficient perpendicular to the magnetic field is typically 0.2, suggesting that transport in latitude is less efficient.

Tri-track: free software for large-scale particle tracking.

PubMed

Vallotton, Pascal; Olivier, Sandra

2013-04-01

The ability to correctly track objects in time-lapse sequences is important in many applications of microscopy. Individual object motions typically display a level of dynamic regularity reflecting the existence of an underlying physics or biology. Best results are obtained when this local information is exploited. Additionally, if the particle number is known to be approximately constant, a large number of tracking scenarios may be rejected on the basis that they are not compatible with a known maximum particle velocity. This represents information of a global nature, which should ideally be exploited too. Some time ago, we devised an efficient algorithm that exploited both types of information. The tracking task was reduced to a max-flow min-cost problem instance through a novel graph structure that comprised vertices representing objects from three consecutive image frames. The algorithm is explained here for the first time. A user-friendly implementation is provided, and the specific relaxation mechanism responsible for the method's effectiveness is uncovered. The software is particularly competitive for complex dynamics such as dense antiparallel flows, or in situations where object displacements are considerable. As an application, we characterize a remarkable vortex structure formed by bacteria engaged in interstitial motility.

Two-dimensional scanning high-energy particle diagnostic system in Large Helical Device

NASA Astrophysics Data System (ADS)

Ozaki, T.; Goncharov, P.; Sudo, S.; Shoji, M.; Kawahata, K.; Kaneko, O.; Murakami, S.

2004-10-01

A high-energy neutral particle measurement is one of the important diagnostics for ion temperature and high-energy particle confinement analysis. The neutral particle analyzer in the large helical device is capable of wide range scanning as a feature. We have obtained various data using the horizontal scan of the analyzer. Recently, in addition to the horizontal scan, a high-speed perpendicular scan became possible which enables acquisition of new information in the poloidal direction. Two stainless blocks are set on the opposite sides of the chain in order to balance the weight (700 kg) of the analyzer and reduce the load for the motor. Therefore a very high scan speed of 1°/s can be obtained. The scanning speed is 1°/s. By adding the vertical scan, the ion temperature profile and the radial variation of the signal loss associated with the resonant loss was obtained in preliminary experimental results.

Study of water-oil emulsion combustion in large pilot power plants for fine particle matter emission reduction

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

Allouis, C.; Beretta, F.; L'Insalata, A.

2007-04-15

The combustion of heavy fuel oil for power generation is a great source of carbonaceous and inorganic particle emissions, even though the combustion technologies and their efficiency are improving. The information about the size distribution function of the particles originated by trace metals present into the fuels is not adequate. In this paper, we focused our attention the influence of emulsion oil-water on the larger distribution mode of both the carbonaceous and metallic particles. Isokinetic sampling was performed at the exhausts of flames of a low-sulphur content heavy oil and its emulsion with water produced in two large pilot plants.more » The samples were size-segregated by mean of an 8-stages Andersen impactor. Further investigation performed on the samples using electronic microscopy (SEM) coupled with X-ray analysis (EDX) evidenced the presence of solid spherical particles, plerosphere, with typical dimensions ranging between 200 nm and 2-3 {mu}m, whose atomic composition contains a large amount of the trace metals present in the parent oils (Fe, V, Ni, etc.). EDX analyses revealed that the metal concentration increases as the plerosphere dimension decreases. We also observed that the use of emulsion slightly reduce the emission of fine particles (D{sub 50} < 8 {mu}m) in the large scale plant. (author)« less

Particle size analysis of amalgam powder and handpiece generated specimens.

PubMed

Drummond, J L; Hathorn, R M; Cailas, M D; Karuhn, R

2001-07-01

The increasing interest in the elimination of amalgam particles from the dental waste (DW) stream, requires efficient devices to remove these particles. The major objective of this project was to perform a comparative evaluation of five basic methods of particle size analysis in terms of the instrument's ability to quantify the size distribution of the various components within the DW stream. The analytical techniques chosen were image analysis via scanning electron microscopy, standard wire mesh sieves, X-ray sedigraphy, laser diffraction, and electrozone analysis. The DW particle stream components were represented by amalgam powders and handpiece/diamond bur generated specimens of enamel; dentin, whole tooth, and condensed amalgam. Each analytical method quantified the examined DW particle stream components. However, X-ray sedigraphy, electrozone, and laser diffraction particle analyses provided similar results for determining particle distributions of DW samples. These three methods were able to more clearly quantify the properties of the examined powder and condensed amalgam samples. Furthermore, these methods indicated that a significant fraction of the DW stream contains particles less than 20 microm. The findings of this study indicated that the electrozone method is likely to be the most effective technique for quantifying the particle size distribution in the DW particle stream. This method required a relative small volume of sample, was not affected by density, shape factors or optical properties, and measured a sufficient number of particles to provide a reliable representation of the particle size distribution curve.

Mean-field approaches to the totally asymmetric exclusion process with quenched disorder and large particles

NASA Astrophysics Data System (ADS)

Shaw, Leah B.; Sethna, James P.; Lee, Kelvin H.

2004-08-01

The process of protein synthesis in biological systems resembles a one-dimensional driven lattice gas in which the particles (ribosomes) have spatial extent, covering more than one lattice site. Realistic, nonuniform gene sequences lead to quenched disorder in the particle hopping rates. We study the totally asymmetric exclusion process with large particles and quenched disorder via several mean-field approaches and compare the mean-field results with Monte Carlo simulations. Mean-field equations obtained from the literature are found to be reasonably effective in describing this system. A numerical technique is developed for computing the particle current rapidly. The mean-field approach is extended to include two-point correlations between adjacent sites. The two-point results are found to match Monte Carlo simulations more closely.

On the interpolation of light-scattering responses from irregularly shaped particles

NASA Astrophysics Data System (ADS)

Videen, Gorden; Zubko, Evgenij; Arnold, Jessica A.; MacCall, Benjamin; Weinberger, Alycia J.; Shkuratov, Yuriy; Muñoz, Olga

2018-05-01

Common particle characteristics needed for many applications may include size, eccentricity, porosity and refractive index. Determining such characteristics from scattered light is a primary goal of remote sensing. For other applications, like differentiating a hazardous particle from the natural background, information about higher fidelity particle characteristics may be required, including specific shape or chemical composition. While a complete characterization of a particle system from its scattered light through the inversion process remains unachievable, great strides have been made in providing information in the form of constraints on particle characteristics. Recent advances have been made in quantifying the characteristics of polydispersions of irregularly shaped particles by making comparisons of the light-scattering signals from model simulant particles. We show that when the refractive index is changed, the light-scattering characteristics from polydispersions of such particles behave monotonically over relatively large parameter ranges compared with those of monodisperse distributions of particles having regular shapes, like spheres, spheroids, etc. This allows for their properties to be interpolated, which results in a significant reduction of the computational load when performing inversions.

Generation of dense granular deposits for porosity analysis: assessment and application of large-scale non-smooth granular dynamics

NASA Astrophysics Data System (ADS)

Schruff, T.; Liang, R.; Rüde, U.; Schüttrumpf, H.; Frings, R. M.

2018-01-01

The knowledge of structural properties of granular materials such as porosity is highly important in many application-oriented and scientific fields. In this paper we present new results of computer-based packing simulations where we use the non-smooth granular dynamics (NSGD) method to simulate gravitational random dense packing of spherical particles with various particle size distributions and two types of depositional conditions. A bin packing scenario was used to compare simulation results to laboratory porosity measurements and to quantify the sensitivity of the NSGD regarding critical simulation parameters such as time step size. The results of the bin packing simulations agree well with laboratory measurements across all particle size distributions with all absolute errors below 1%. A large-scale packing scenario with periodic side walls was used to simulate the packing of up to 855,600 spherical particles with various particle size distributions (PSD). Simulation outcomes are used to quantify the effect of particle-domain-size ratio on the packing compaction. A simple correction model, based on the coordination number, is employed to compensate for this effect on the porosity and to determine the relationship between PSD and porosity. Promising accuracy and stability results paired with excellent computational performance recommend the application of NSGD for large-scale packing simulations, e.g. to further enhance the generation of representative granular deposits.

Quantifying the uncertainty in heritability.

PubMed

Furlotte, Nicholas A; Heckerman, David; Lippert, Christoph

2014-05-01

The use of mixed models to determine narrow-sense heritability and related quantities such as SNP heritability has received much recent attention. Less attention has been paid to the inherent variability in these estimates. One approach for quantifying variability in estimates of heritability is a frequentist approach, in which heritability is estimated using maximum likelihood and its variance is quantified through an asymptotic normal approximation. An alternative approach is to quantify the uncertainty in heritability through its Bayesian posterior distribution. In this paper, we develop the latter approach, make it computationally efficient and compare it to the frequentist approach. We show theoretically that, for a sufficiently large sample size and intermediate values of heritability, the two approaches provide similar results. Using the Atherosclerosis Risk in Communities cohort, we show empirically that the two approaches can give different results and that the variance/uncertainty can remain large.

Quantifying the uncertainty in heritability

PubMed Central

Furlotte, Nicholas A; Heckerman, David; Lippert, Christoph

2014-01-01

The use of mixed models to determine narrow-sense heritability and related quantities such as SNP heritability has received much recent attention. Less attention has been paid to the inherent variability in these estimates. One approach for quantifying variability in estimates of heritability is a frequentist approach, in which heritability is estimated using maximum likelihood and its variance is quantified through an asymptotic normal approximation. An alternative approach is to quantify the uncertainty in heritability through its Bayesian posterior distribution. In this paper, we develop the latter approach, make it computationally efficient and compare it to the frequentist approach. We show theoretically that, for a sufficiently large sample size and intermediate values of heritability, the two approaches provide similar results. Using the Atherosclerosis Risk in Communities cohort, we show empirically that the two approaches can give different results and that the variance/uncertainty can remain large. PMID:24670270

Characterization of Thylakoid-Derived Lipid-Protein Particles Bearing the Large Subunit of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase.

PubMed Central

Smith, M. D.; Ghosh, S.; Dumbroff, E. B.; Thompson, J. E.

1997-01-01

Lipid-protein particles bearing the 55-kD ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (EC 4.1.1.39) large subunit (RLSU) and no detectable corresponding Rubisco small subunit (RSSU) were isolated from the stroma of intact chloroplasts by flotation centrifugation. Stromal RLSU-bearing particles appear to originate from thylakoids because they can also be generated in vitro by illumination of isolated thylakoids. Their formation in vitro is largely heat denaturable and is facilitated by light or ATP. RLSU-containing lipid-protein particles range from 0.05 to 0.10 [mu]m in radius, contain the same fatty acids as thylakoids, but have a 10- to 15-fold higher free-to-esterified fatty acid ratio than thylakoids. RLSU-bearing lipid-protein particles with no detectable RSSU were also immunopurified from the populations of both stromal lipid-protein particles and those generated in vitro from illuminated thylakoids. Protease shaving indicated that the RLSU is embedded in the lipid-protein particles and that there is also a protease-protected RLSU in thylakoids. These observations collectively indicate that the RLSU associated with thylakoids is released into the stroma by light-facilitated blebbing of lipid-protein particles. The release of RLSU-containing particles may in turn be coordinated with the assembly of Rubisco holoenzyme because chaperonin 60 is also associated with lipid-protein particles isolated from stroma. PMID:12223858

Virtually distortion-free imaging system for large field, high resolution lithography using electrons, ions or other particle beams

DOEpatents

Hawryluk, A.M.; Ceglio, N.M.

1993-01-12

Virtually distortion free large field high resolution imaging is performed using an imaging system which contains large field distortion or field curvature. A reticle is imaged in one direction through the optical system to form an encoded mask. The encoded mask is then imaged back through the imaging system onto a wafer positioned at the reticle position. Particle beams, including electrons, ions and neutral particles, may be used as well as electromagnetic radiation.

Virtually distortion-free imaging system for large field, high resolution lithography using electrons, ions or other particle beams

DOEpatents

Hawryluk, Andrew M.; Ceglio, Natale M.

1993-01-01

Virtually distortion free large field high resolution imaging is performed using an imaging system which contains large field distortion or field curvature. A reticle is imaged in one direction through the optical system to form an encoded mask. The encoded mask is then imaged back through the imaging system onto a wafer positioned at the reticle position. Particle beams, including electrons, ions and neutral particles, may be used as well as electromagnetic radiation.

Microscale simulations of shock interaction with large assembly of particles for developing point-particle models

NASA Astrophysics Data System (ADS)

Thakur, Siddharth; Neal, Chris; Mehta, Yash; Sridharan, Prasanth; Jackson, Thomas; Balachandar, S.

2017-01-01

Micrsoscale simulations are being conducted for developing point-particle and other related models that are needed for the mesoscale and macroscale simulations of explosive dispersal of particles. These particle models are required to compute (a) instantaneous aerodynamic force on the particle and (b) instantaneous net heat transfer between the particle and the surrounding. A strategy for a sequence of microscale simulations has been devised that allows systematic development of the hybrid surrogate models that are applicable at conditions representative of the explosive dispersal application. The ongoing microscale simulations seek to examine particle force dependence on: (a) Mach number, (b) Reynolds number, and (c) volume fraction (different particle arrangements such as cubic, face-centered cubic (FCC), body-centered cubic (BCC) and random). Future plans include investigation of sequences of fully-resolved microscale simulations consisting of an array of particles subjected to more realistic time-dependent flows that progressively better approximate the actual problem of explosive dispersal. Additionally, effects of particle shape, size, and number in simulation as well as the transient particle deformation dependence on various parameters including: (a) particle material, (b) medium material, (c) multiple particles, (d) incoming shock pressure and speed, (e) medium to particle impedance ratio, (f) particle shape and orientation to shock, etc. are being investigated.

A regularized vortex-particle mesh method for large eddy simulation

NASA Astrophysics Data System (ADS)

Spietz, H. J.; Walther, J. H.; Hejlesen, M. M.

2017-11-01

We present recent developments of the remeshed vortex particle-mesh method for simulating incompressible fluid flow. The presented method relies on a parallel higher-order FFT based solver for the Poisson equation. Arbitrary high order is achieved through regularization of singular Green's function solutions to the Poisson equation and recently we have derived novel high order solutions for a mixture of open and periodic domains. With this approach the simulated variables may formally be viewed as the approximate solution to the filtered Navier Stokes equations, hence we use the method for Large Eddy Simulation by including a dynamic subfilter-scale model based on test-filters compatible with the aforementioned regularization functions. Further the subfilter-scale model uses Lagrangian averaging, which is a natural candidate in light of the Lagrangian nature of vortex particle methods. A multiresolution variation of the method is applied to simulate the benchmark problem of the flow past a square cylinder at Re = 22000 and the obtained results are compared to results from the literature.

Life and death of a single catalytic cracking particle

PubMed Central

Meirer, Florian; Kalirai, Sam; Morris, Darius; Soparawalla, Santosh; Liu, Yijin; Mesu, Gerbrand; Andrews, Joy C.; Weckhuysen, Bert M.

2015-01-01

Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for example, gasoline). In this process, metal deposition and intrusion is a major cause for irreversible catalyst deactivation and shifts in product distribution. We used x-ray nanotomography of industrial FCC particles at differing degrees of deactivation to quantify changes in single-particle macroporosity and pore connectivity, correlated to iron and nickel deposition. Our study reveals that these metals are incorporated almost exclusively in near-surface regions, severely limiting macropore accessibility as metal concentrations increase. Because macropore channels are “highways” of the pore network, blocking them prevents feedstock molecules from reaching the catalytically active domains. Consequently, metal deposition reduces conversion with time on stream because the internal pore volume, although itself unobstructed, becomes largely inaccessible. PMID:26601160

Characteristics of large three-dimensional heaps of particles produced by ballistic deposition from extended sources

NASA Astrophysics Data System (ADS)

Topic, Nikola; Gallas, Jason A. C.; Pöschel, Thorsten

2013-11-01

This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area. We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source.

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.

Use of incomplete energy recovery for the energy compression of large energy spread charged particle beams

DOEpatents

Douglas, David R [Newport News, VA; Benson, Stephen V [Yorktown, VA

2007-01-23

A method of energy recovery for RF-base linear charged particle accelerators that allows energy recovery without large relative momentum spread of the particle beam involving first accelerating a waveform particle beam having a crest and a centroid with an injection energy E.sub.o with the centroid of the particle beam at a phase offset f.sub.o from the crest of the accelerating waveform to an energy E.sub.full and then recovering the beam energy centroid a phase f.sub.o+Df relative to the crest of the waveform particle beam such that (E.sub.full-E.sub.o)(1+cos(f.sub.o+Df))>dE/2 wherein dE=the full energy spread, dE/2=the full energy half spread and Df=the wave form phase distance.

Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood

PubMed Central

Vis, Bradley; Pele, Laetitia C.; Faria, Nuno; Powell, Jonathan J.

2017-01-01

Abstract Pigment grade titanium dioxide is composed of sub‐micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell–particle associations could be determined in immune cells of human whole blood at “real life” concentrations. In vitro assays, initially using isolated peripheral blood mononuclear cells, identified titanium dioxide associated with the surface of, and within, immune cells by darkfield reflectance in imaging flow cytometry. This was confirmed at the population level by side scatter measurements using conventional flow cytometry. Next, it was demonstrated that imaging flow cytometry could quantify titanium dioxide particle‐bearing cells, within the immune cell populations of fresh whole blood, down to titanium dioxide levels of 10 parts per billion, which is in the range anticipated for human blood following titanium dioxide ingestion. Moreover, surface association and internal localization of titanium dioxide particles could be discriminated in the assays. Overall, results showed that in addition to the anticipated activity of blood monocytes internalizing titanium dioxide particles, neutrophil internalization and cell membrane adhesion also occurred, the latter for both phagocytic and nonphagocytic cell types. What happens in vivo and whether this contributes to activation of one or more of these different cells types in blood merits further attention. © 2017 The Authors. Cytometry Part A Published by Wiley Periodicals, Inc. on behalf of ISAC. PMID:28941170

Neural basis for generalized quantifier comprehension.

PubMed

McMillan, Corey T; Clark, Robin; Moore, Peachie; Devita, Christian; Grossman, Murray

2005-01-01

Generalized quantifiers like "all cars" are semantically well understood, yet we know little about their neural representation. Our model of quantifier processing includes a numerosity device, operations that combine number elements and working memory. Semantic theory posits two types of quantifiers: first-order quantifiers identify a number state (e.g. "at least 3") and higher-order quantifiers additionally require maintaining a number state actively in working memory for comparison with another state (e.g. "less than half"). We used BOLD fMRI to test the hypothesis that all quantifiers recruit inferior parietal cortex associated with numerosity, while only higher-order quantifiers recruit prefrontal cortex associated with executive resources like working memory. Our findings showed that first-order and higher-order quantifiers both recruit right inferior parietal cortex, suggesting that a numerosity component contributes to quantifier comprehension. Moreover, only probes of higher-order quantifiers recruited right dorsolateral prefrontal cortex, suggesting involvement of executive resources like working memory. We also observed activation of thalamus and anterior cingulate that may be associated with selective attention. Our findings are consistent with a large-scale neural network centered in frontal and parietal cortex that supports comprehension of generalized quantifiers.

Particle production at energies available at the CERN Large Hadron Collider within an evolutionary model

NASA Astrophysics Data System (ADS)

Sinyukov, Yu. M.; Shapoval, V. M.

2018-06-01

The particle yields and particle number ratios in Pb+Pb collisions at the CERN Large Hadron Collider (LHC) energy √{sN N}=2.76 TeV are described within the integrated hydrokinetic model (iHKM) at two different equations of state (EoS) for quark-gluon matter and the two corresponding hadronization temperatures T =165 MeV and T =156 MeV. The role of particle interactions at the final afterburner stage of the collision in the particle production is investigated by means of comparison of the results of full iHKM simulations with those where the annihilation and other inelastic processes (except for resonance decays) are switched off after hadronization/particlization, similarly as in the thermal models. An analysis supports the picture of continuous chemical freeze-out in the sense that the corrections to the sudden chemical freeze-out results, which arise because of the inelastic reactions at the subsequent evolution times, are noticeable and improve the description of particle number ratios. An important observation is that, although the particle number ratios with switched-off inelastic reactions are quite different at different particlization temperatures which are adopted for different equations of state to reproduce experimental data, the complete iHKM calculations bring very close results in both cases.

Electrokinetic and hydrodynamic properties of charged-particles systems. From small electrolyte ions to large colloids

NASA Astrophysics Data System (ADS)

Nägele, G.; Heinen, M.; Banchio, A. J.; Contreras-Aburto, C.

2013-11-01

Dynamic processes in dispersions of charged spherical particles are of importance both in fundamental science, and in technical and bio-medical applications. There exists a large variety of charged-particles systems, ranging from nanometer-sized electrolyte ions to micron-sized charge-stabilized colloids. We review recent advances in theoretical methods for the calculation of linear transport coefficients in concentrated particulate systems, with the focus on hydrodynamic interactions and electrokinetic effects. Considered transport properties are the dispersion viscosity, self- and collective diffusion coefficients, sedimentation coefficients, and electrophoretic mobilities and conductivities of ionic particle species in an external electric field. Advances by our group are also discussed, including a novel mode-coupling-theory method for conduction-diffusion and viscoelastic properties of strong electrolyte solutions. Furthermore, results are presented for dispersions of solvent-permeable particles, and particles with non-zero hydrodynamic surface slip. The concentration-dependent swelling of ionic microgels is discussed, as well as a far-reaching dynamic scaling behavior relating colloidal long- to short-time dynamics.

Simulation of the radiation exposure in space during a large solar energetic particle event with GEANT4

NASA Astrophysics Data System (ADS)

Matthiä, Daniel; Berger, Thomas; Puchalska, Monika; Reitz, Guenther

The radiation field in space is complex due to the various contributing sources and astronauts at the International Space Station (ISS) in low Earth orbit or beyond are exposed to significantly increased doses compared to on ground or in the lower atmosphere. The main sources of the increased radiation level are Galactic Cosmic Ray (GCR) particles, mainly fully charged ions from hydrogen to iron with energies up to hundreds of GeV per nucleon and more, trapped protons from the radiation belts with energies up to several hundreds of MeV, and solar energetic particles up to several GeV released in large eruptions on the sun related to solar x-ray flares and coronal mass ejections. While the intensities of Galactic Cosmic Rays and trapped protons are relatively stable and changing slowly over the solar cycle, solar energetic particle events last for several hours up to days and are characterized by strong increases in the particle intensity. The radiation exposure during a large particle event can be very harmful to astronauts especially during extra vehicular activities and outside the protective magnetic field of the Earth. The MATROSHKA human phantom was and is used on the International Space Station to measure the radiation exposure in and outside ISS in order to evaluate the radiation risk in low Earth orbit. A voxel-based description of the MATROSHKA phantom (NUNDO-Numerical RANDO Model) was used in the present work to numerically estimate the radiation exposure of the human body and the individual organs during a large solar particle event. The transport of primary protons following an exponential energy distribution was simulated in order to calculate the energy deposition and organ doses in the MATROSHKA phantom during such an event taking into account different amounts of shielding provided by a surrounding aluminum shell. The primary particle energy distribution used in this work follows the description of the spectrum of the solar energetic particle event

Vacuum cleaner emissions as a source of indoor exposure to airborne particles and bacteria.

PubMed

Knibbs, Luke D; He, Congrong; Duchaine, Caroline; Morawska, Lidia

2012-01-03

Vacuuming can be a source of indoor exposure to biological and nonbiological aerosols, although there are few data that describe the magnitude of emissions from the vacuum cleaner itself. We therefore sought to quantify emission rates of particles and bacteria from a large group of vacuum cleaners and investigate their potential determinants, including temperature, dust bags, exhaust filters, price, and age. Emissions of particles between 0.009 and 20 μm and bacteria were measured from 21 vacuums. Ultrafine (<100 nm) particle emission rates ranged from 4.0 × 10(6) to 1.1 × 10(11) particles min(-1). Emission of 0.54-20 μm particles ranged from 4.0 × 10(4) to 1.2 × 10(9) particles min(-1). PM(2.5) emissions were between 2.4 × 10(-1) and 5.4 × 10(3) μg min(-1). Bacteria emissions ranged from 0 to 7.4 × 10(5) bacteria min(-1) and were poorly correlated with dust bag bacteria content and particle emissions. Large variability in emission of all parameters was observed across the 21 vacuums, which was largely not attributable to the range of determinant factors we assessed. Vacuum cleaner emissions contribute to indoor exposure to nonbiological and biological aerosols when vacuuming, and this may vary markedly depending on the vacuum used.

Aerosol pH buffering in the southeastern US: Fine particles remain highly acidic despite large reductions in sulfate

NASA Astrophysics Data System (ADS)

Weber, R. J.; Guo, H.; Russell, A. G.; Nenes, A.

2015-12-01

pH is a critical aerosol property that impacts many atmospheric processes, including biogenic secondary organic aerosol formation, gas-particle phase partitioning, and mineral dust or redox metal mobilization. Particle pH has also been linked to adverse health effects. Using a comprehensive data set from the Southern Oxidant and Aerosol Study (SOAS) as the basis for thermodynamic modeling, we have shown that particles are currently highly acidic in the southeastern US, with pH between 0 and 2. Sulfate and ammonium are the main acid-base components that determine particle pH in this region, however they have different sources and their concentrations are changing. Over 15 years of network data show that sulfur dioxide emission reductions have resulted in a roughly 70 percent decrease in sulfate, whereas ammonia emissions, mainly link to agricultural activities, have been largely steady, as have gas phase ammonia concentrations. This has led to the view that particles are becoming more neutralized. However, sensitivity analysis, based on thermodynamic modeling, to changing sulfate concentrations indicates that particles have remained highly acidic over the past decade, despite the large reductions in sulfate. Furthermore, anticipated continued reductions of sulfate and relatively constant ammonia emissions into the future will not significantly change particle pH until sulfate drops to clean continental background levels. The result reshapes our expectation of future particle pH and implies that atmospheric processes and adverse health effects linked to particle acidity will remain unchanged for some time into the future.

Method for determining aerosol particle size device for determining aerosol particle size

DOEpatents

Novick, Vincent J.

1998-01-01

A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data.

Process for preparation of large-particle-size monodisperse latexes

NASA Technical Reports Server (NTRS)

Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, D. M. (Inventor)

1981-01-01

Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarge particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment.

Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation.

PubMed

Niemelä, R; Koskela, H; Engström, K

2001-08-01

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field.

Novel Optical Diagnostic Techniques for Studying Particle Deposition Upon Large Cylinders in a Sheared Suspension

NASA Technical Reports Server (NTRS)

Yoda, M.; Bailey, B. C.

2000-01-01

On a twelve-month voyage to Mars, one astronaut will require at least two tons of potable water and two tons of pure oxygen. Efficient, reliable fluid reclamation is therefore necessary for manned space exploration. Space habitats require a compact, flexible, and robust apparatus capable of solid-fluid mechanical separation over a wide range of fluid and particle densities and particle sizes. In space, centrifugal filtration, where particles suspended in fluid are captured by rotating fixed-fiber mat filters, is a logical candidate for mechanical separation. Non-colloidal particles are deposited on the fibers due to inertial impaction or direct interception. Since rotation rates are easily adjustable, inertial effects are the most practical way to control separation rates for a wide variety of multiphase mixtures in variable gravity environments. Understanding how fluid inertia and differential fluid-particle inertia, characterized by the Reynolds and Stokes numbers, respectively, affect deposition is critical in optimizing filtration in a microgravity environment. This work will develop non-intrusive optical diagnostic techniques for directly visualizing where and when non-colloidal particles deposit upon, or contact, solid surfaces: 'particle proximity sensors'. To model particle deposition upon a single filter fiber, these sensors will be used in ground-based experiments to study particle dynamics as in the vicinity of a large (compared with the particles) cylinder in a simply sheared (i.e., linearly-varying, zero-mean velocity profile) neutrally-buoyant, refractive-index matched solid-liquid suspension.

A Grouping Particle Swarm Optimizer with Personal-Best-Position Guidance for Large Scale Optimization.

PubMed

Guo, Weian; Si, Chengyong; Xue, Yu; Mao, Yanfen; Wang, Lei; Wu, Qidi

2017-05-04

Particle Swarm Optimization (PSO) is a popular algorithm which is widely investigated and well implemented in many areas. However, the canonical PSO does not perform well in population diversity maintenance so that usually leads to a premature convergence or local optima. To address this issue, we propose a variant of PSO named Grouping PSO with Personal- Best-Position (Pbest) Guidance (GPSO-PG) which maintains the population diversity by preserving the diversity of exemplars. On one hand, we adopt uniform random allocation strategy to assign particles into different groups and in each group the losers will learn from the winner. On the other hand, we employ personal historical best position of each particle in social learning rather than the current global best particle. In this way, the exemplars diversity increases and the effect from the global best particle is eliminated. We test the proposed algorithm to the benchmarks in CEC 2008 and CEC 2010, which concern the large scale optimization problems (LSOPs). By comparing several current peer algorithms, GPSO-PG exhibits a competitive performance to maintain population diversity and obtains a satisfactory performance to the problems.

Trojan particles: Large porous carriers of nanoparticles for drug delivery

PubMed Central

Tsapis, N.; Bennett, D.; Jackson, B.; Weitz, D. A.; Edwards, D. A.

2002-01-01

We have combined the drug release and delivery potential of nanoparticle (NP) systems with the ease of flow, processing, and aerosolization potential of large porous particle (LPP) systems by spray drying solutions of polymeric and nonpolymeric NPs into extremely thin-walled macroscale structures. These hybrid LPPs exhibit much better flow and aerosolization properties than the NPs; yet, unlike the LPPs, which dissolve in physiological conditions to produce molecular constituents, the hybrid LPPs dissolve to produce NPs, with the drug release and delivery advantages associated with NP delivery systems. Formation of the large porous NP (LPNP) aggregates occurs via a spray-drying process that ensures the drying time of the sprayed droplet is sufficiently shorter than the characteristic time for redistribution of NPs by diffusion within the drying droplet, implying a local Peclet number much greater than unity. Additional control over LPNPs physical characteristics is achieved by adding other components to the spray-dried solutions, including sugars, lipids, polymers, and proteins. The ability to produce LPNPs appears to be largely independent of molecular component type as well as the size or chemical nature of the NPs. PMID:12200546

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.

Landscape of supersymmetric particle mass hierarchies and their signature space at the CERN Large Hadron Collider.

PubMed

Feldman, Daniel; Liu, Zuowei; Nath, Pran

2007-12-21

The minimal supersymmetric standard model with soft breaking has a large landscape of supersymmetric particle mass hierarchies. This number is reduced significantly in well-motivated scenarios such as minimal supergravity and alternatives. We carry out an analysis of the landscape for the first four lightest particles and identify at least 16 mass patterns, and provide benchmarks for each. We study the signature space for the patterns at the CERN Large Hadron Collider by analyzing the lepton+ (jet> or =2) + missing P{T} signals with 0, 1, 2, and 3 leptons. Correlations in missing P{T} are also analyzed. It is found that even with 10 fb{-1} of data a significant discrimination among patterns emerges.

Method for determining aerosol particle size, device for determining aerosol particle size

DOEpatents

Novick, V.J.

1998-10-06

A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data. 2 figs.

Large Eddy Simulation of Transient Flow, Solidification, and Particle Transport Processes in Continuous-Casting Mold

NASA Astrophysics Data System (ADS)

Liu, Zhongqiu; Li, Linmin; Li, Baokuan; Jiang, Maofa

2014-07-01

The current study developed a coupled computational model to simulate the transient fluid flow, solidification, and particle transport processes in a slab continuous-casting mold. Transient flow of molten steel in the mold is calculated using the large eddy simulation. An enthalpy-porosity approach is used for the analysis of solidification processes. The transport of bubble and non-metallic inclusion inside the liquid pool is calculated using the Lagrangian approach based on the transient flow field. A criterion of particle entrapment in the solidified shell is developed using the user-defined functions of FLUENT software (ANSYS, Inc., Canonsburg, PA). The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern inside the liquid pool exhibits quite satisfactory agreement with the corresponding measurements. The predicted complex instantaneous velocity field is composed of various small recirculation zones and multiple vortices. The transport of particles inside the liquid pool and the entrapment of particles in the solidified shell are not symmetric. The Magnus force can reduce the entrapment ratio of particles in the solidified shell, especially for smaller particles, but the effect is not obvious. The Marangoni force can play an important role in controlling the motion of particles, which increases the entrapment ratio of particles in the solidified shell obviously.

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

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

Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.

The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected tomore » mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.« less

Initial results from the LAPD wave-particle experiment and simulation

NASA Astrophysics Data System (ADS)

Bortnik, J.; Tao, X.; Albert, J. M.; Thorne, R. M.; Gekelman, W. N.; Pribyl, P.; Van Compernolle, B.

2011-12-01

We present the initial results obtained from a unique experiment-theory project. This project is designed to study the detailed nature of the wave-particle interactions between energetic electrons and whistler-mode waves. Using the Large-Plasma device at UCLA, whistler mode waves are injected into one end of the machine and a beam of energetic electrons is injected at the opposite ends. When the first-order resonance condition is met, the electron beam is scattered, which is measured with a novel energy-pitch-angle analyzer. To support the experiment, a flexible test-particle code is constructed which is able to quantify the scattering of charged particles in response to any distribution of waves, in an arbitrary field geometry. The results of the experiment are discussed and placed into the context of space physics and specifically the upcoming Radiation Belt Storm Probes mission.

An integrated micromechanical large particle in flow sorter (MILPIS)

NASA Astrophysics Data System (ADS)

Fuad, Nurul M.; Skommer, Joanna; Friedrich, Timo; Kaslin, Jan; Wlodkowic, Donald

2015-06-01

At present, the major hurdle to widespread deployment of zebrafish embryo and larvae in large-scale drug development projects is lack of enabling high-throughput analytical platforms. In order to spearhead drug discovery with the use of zebrafish as a model, platforms need to integrate automated pre-test sorting of organisms (to ensure quality control and standardization) and their in-test positioning (suitable for high-content imaging) with modules for flexible drug delivery. The major obstacle hampering sorting of millimetre sized particles such as zebrafish embryos on chip-based devices is their substantial diameter (above one millimetre), mass (above one milligram), which both lead to rapid gravitational-induced sedimentation and high inertial forces. Manual procedures associated with sorting hundreds of embryos are very monotonous and as such prone to significant analytical errors due to operator's fatigue. In this work, we present an innovative design of a micromechanical large particle in-flow sorter (MILPIS) capable of analysing, sorting and dispensing living zebrafish embryos for drug discovery applications. The system consisted of a microfluidic network, revolving micromechanical receptacle actuated by robotic servomotor and opto-electronic sensing module. The prototypes were fabricated in poly(methyl methacrylate) (PMMA) transparent thermoplastic using infrared laser micromachining. Elements of MILPIS were also fabricated in an optically transparent VisiJet resin using 3D stereolithography (SLA) processes (ProJet 7000HD, 3D Systems). The device operation was based on a rapidly revolving miniaturized mechanical receptacle. The latter function was to hold and position individual fish embryos for (i) interrogation, (ii) sorting decision-making and (iii) physical sorting..The system was designed to separate between fertilized (LIVE) and non-fertilized (DEAD) eggs, based on optical transparency using infrared (IR) emitters and receivers embedded in the system

Computational study of scattering of a zero-order Bessel beam by large nonspherical homogeneous particles with the multilevel fast multipole algorithm

NASA Astrophysics Data System (ADS)

Yang, Minglin; Wu, Yueqian; Sheng, Xinqing; Ren, Kuan Fang

2017-12-01

Computation of scattering of shaped beams by large nonspherical particles is a challenge in both optics and electromagnetics domains since it concerns many research fields. In this paper, we report our new progress in the numerical computation of the scattering diagrams. Our algorithm permits to calculate the scattering of a particle of size as large as 110 wavelengths or 700 in size parameter. The particle can be transparent or absorbing of arbitrary shape, smooth or with a sharp surface, such as the Chebyshev particles or ice crystals. To illustrate the capacity of the algorithm, a zero order Bessel beam is taken as the incident beam, and the scattering of ellipsoidal particles and Chebyshev particles are taken as examples. Some special phenomena have been revealed and examined. The scattering problem is formulated with the combined tangential formulation and solved iteratively with the aid of the multilevel fast multipole algorithm, which is well parallelized with the message passing interface on the distributed memory computer platform using the hybrid partitioning strategy. The numerical predictions are compared with the results of the rigorous method for a spherical particle to validate the accuracy of the approach. The scattering diagrams of large ellipsoidal particles with various parameters are examined. The effect of aspect ratios, as well as half-cone angle of the incident zero-order Bessel beam and the off-axis distance on scattered intensity, is studied. Scattering by asymmetry Chebyshev particle with size parameter larger than 700 is also given to show the capability of the method for computing scattering by arbitrary shaped particles.

Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects

NASA Astrophysics Data System (ADS)

Autiero, D.; Äystö, J.; Badertscher, A.; Bezrukov, L.; Bouchez, J.; Bueno, A.; Busto, J.; Campagne, J.-E.; Cavata, Ch; Chaussard, L.; de Bellefon, A.; Déclais, Y.; Dumarchez, J.; Ebert, J.; Enqvist, T.; Ereditato, A.; von Feilitzsch, F.; Fileviez Perez, P.; Göger-Neff, M.; Gninenko, S.; Gruber, W.; Hagner, C.; Hess, M.; Hochmuth, K. A.; Kisiel, J.; Knecht, L.; Kreslo, I.; Kudryavtsev, V. A.; Kuusiniemi, P.; Lachenmaier, T.; Laffranchi, M.; Lefievre, B.; Lightfoot, P. K.; Lindner, M.; Maalampi, J.; Maltoni, M.; Marchionni, A.; Marrodán Undagoitia, T.; Marteau, J.; Meregaglia, A.; Messina, M.; Mezzetto, M.; Mirizzi, A.; Mosca, L.; Moser, U.; Müller, A.; Natterer, G.; Oberauer, L.; Otiougova, P.; Patzak, T.; Peltoniemi, J.; Potzel, W.; Pistillo, C.; Raffelt, G. G.; Rondio, E.; Roos, M.; Rossi, B.; Rubbia, A.; Savvinov, N.; Schwetz, T.; Sobczyk, J.; Spooner, N. J. C.; Stefan, D.; Tonazzo, A.; Trzaska, W.; Ulbricht, J.; Volpe, C.; Winter, J.; Wurm, M.; Zalewska, A.; Zimmermann, R.

2007-11-01

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

Artificial neural network based particle size prediction of polymeric nanoparticles.

PubMed

Youshia, John; Ali, Mohamed Ehab; Lamprecht, Alf

2017-10-01

Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificial neural network including these properties as input with particle size and polydispersity index as output. The established model successfully predicted particle size of nanoparticles covering a range of 70-400nm prepared from other polymers. The percentage bias for particle prediction was 2%, 4% and 6%, for the training, validation and testing data, respectively. Polymer surface activity was found to have the highest impact on the particle size followed by viscosity and finally hydrophobicity. Results of this study successfully highlighted polymer properties affecting particle size and confirmed the usefulness of artificial neural networks in predicting the particle size and polydispersity of polymeric nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Shape effects in the turbulent tumbling of large particles

NASA Astrophysics Data System (ADS)

Variano, Evan; Oehmke, Theresa; Pujara, Nimish

2017-11-01

We present laboratory results on rotation of finite-sized, neutrally buoyant, anisotropic particles in isotropic turbulence. The isotropic turbulent flow is generated using a randomly-actuated synthetic jet array that minimizes tank scale circulation and measurements are made with stereoscopic particle image velocimetry. By using particles of different shapes, we explore the effects that symmetries have on particle rotation. We add to previous data collected for spheres cylinders and ellipsoids by performing new measurements on cubes, cuboids and cones. The measurement technique and results on mean-square particle rotation will be presented. Preliminary results, at the time of writing this abstract, indicate that symmetry breaking increases the rate of particle rotation. More complete quantitative results will be presented. This work was partially supported by the NSF award ENG-1604026 and by the Army Research Office Biomathematics Program.

DIRAC in Large Particle Physics Experiments

NASA Astrophysics Data System (ADS)

Stagni, F.; Tsaregorodtsev, A.; Arrabito, L.; Sailer, A.; Hara, T.; Zhang, X.; Consortium, DIRAC

2017-10-01

The DIRAC project is developing interware to build and operate distributed computing systems. It provides a development framework and a rich set of services for both Workload and Data Management tasks of large scientific communities. A number of High Energy Physics and Astrophysics collaborations have adopted DIRAC as the base for their computing models. DIRAC was initially developed for the LHCb experiment at LHC, CERN. Later, the Belle II, BES III and CTA experiments as well as the linear collider detector collaborations started using DIRAC for their computing systems. Some of the experiments built their DIRAC-based systems from scratch, others migrated from previous solutions, ad-hoc or based on different middlewares. Adaptation of DIRAC for a particular experiment was enabled through the creation of extensions to meet their specific requirements. Each experiment has a heterogeneous set of computing and storage resources at their disposal that were aggregated through DIRAC into a coherent pool. Users from different experiments can interact with the system in different ways depending on their specific tasks, expertise level and previous experience using command line tools, python APIs or Web Portals. In this contribution we will summarize the experience of using DIRAC in particle physics collaborations. The problems of migration to DIRAC from previous systems and their solutions will be presented. An overview of specific DIRAC extensions will be given. We hope that this review will be useful for experiments considering an update, or for those designing their computing models.

Quantifying colloidal particle bands and their formation in combined electroosmotic and Poiseuille flow

NASA Astrophysics Data System (ADS)

Yee, Andrew; Cevheri, Necmettin; Yoda, Minami

2015-11-01

Recently, we have shown that suspended radii a = 245 nm particles flowing through a microchannel driven by the combination of a dc electric field and pressure gradient (where the resulting electroosmotic and shear flows are in opposite directions) are attracted to the wall at low electric field magnitude | E | , then assemble into concentrated bands that only exist within a few μm of the wall above a threshold value of | E | , | Ecr | . The ~ 6 μ m wide bands are aligned with the flow direction and are roughly periodic along the cross-stream direction. This talk focuses on quantitative characterization of these bands, for example how | Ecr | , the time required for bands to form after applying the electric field To, and the number of bands depend upon parameters such as particle volume fraction φ, shear rate γ˙ , | E | , and a. The dynamics of the particles within the bands are visualized by imaging a mixture of particles with different fluorescent labels. The visualizations show that the particles are in a liquid state within these bands, and suggest that the particles nearest the wall move in the direction of the electroosmotic flow, while those farther from the wall move in the direction of the shear flow. Supported by NSF.

The rate of equilibration of viscous aerosol particles

NASA Astrophysics Data System (ADS)

O'Meara, Simon; Topping, David O.; McFiggans, Gordon

2016-04-01

The proximity of atmospheric aerosol particles to equilibrium with their surrounding condensable vapours can substantially impact their transformations, fate and impacts and is the subject of vibrant research activity. In this study we first compare equilibration timescales estimated by three different models for diffusion through aerosol particles to assess any sensitivity to choice of model framework. Equilibration times for diffusion coefficients with varying dependencies on composition are compared for the first time. We show that even under large changes in the saturation ratio of a semi-volatile component (es) of 1-90 % predicted equilibration timescales are in agreement, including when diffusion coefficients vary with composition. For condensing water and a diffusion coefficient dependent on composition, a plasticising effect is observed, leading to a decreased estimated equilibration time with increasing final es. Above 60 % final es maximum equilibration times of around 1 s are estimated for comparatively large particles (10 µm) containing a relatively low diffusivity component (1 × 10-25 m2 s-1 in pure form). This, as well as other results here, questions whether particle-phase diffusion through water-soluble particles can limit hygroscopic growth in the ambient atmosphere. In the second part of this study, we explore sensitivities associated with the use of particle radius measurements to infer diffusion coefficient dependencies on composition using a diffusion model. Given quantified similarities between models used in this study, our results confirm considerations that must be taken into account when designing such experiments. Although quantitative agreement of equilibration timescales between models is found, further work is necessary to determine their suitability for assessing atmospheric impacts, such as their inclusion in polydisperse aerosol simulations.

Quantifying uncertainty in morphologically-derived bedload transport rates for large braided rivers: insights from high-resolution, high-frequency digital elevation model differencing

NASA Astrophysics Data System (ADS)

Brasington, J.; Hicks, M.; Wheaton, J. M.; Williams, R. D.; Vericat, D.

2013-12-01

Repeat surveys of channel morphology provide a means to quantify fluvial sediment storage and enable inferences about changes in long-term sediment supply, watershed delivery and bed level adjustment; information vital to support effective river and land management. Over shorter time-scales, direct differencing of fluvial terrain models may also offer a route to predict reach-averaged sediment transport rates and quantify the patterns of channel morphodynamics and the processes that force them. Recent and rapid advances in geomatics have facilitated these goals by enabling the acquisition of topographic data at spatial resolutions and precisions suitable for characterising river morphology at the scale of individual grains over multi-kilometre reaches. Despite improvements in topographic surveying, inverting the terms of the sediment budget to derive estimates of sediment transport and link these to morphodynamic processes is, nonetheless, often confounded by limited knowledge of either the sediment supply or efflux across a boundary of the control volume, or unobserved cut-and-fill taking place between surveys. This latter problem is particularly poorly constrained, as field logistics frequently preclude surveys at a temporal frequency sufficient to capture changes in sediment storage associated with each competent event, let alone changes during individual floods. In this paper, we attempt to quantify the principal sources of uncertainty in morphologically-derived bedload transport rates for the large, labile, gravel-bed braided Rees River which drains the Southern Alps of NZ. During the austral summer of 2009-10, a unique timeseries of 10 high quality DEMs was derived for a 3 x 0.7 km reach of the Rees, using a combination of mobile terrestrial laser scanning, aDcp soundings and aerial image analysis. Complementary measurements of the forcing flood discharges and estimates of event-based particle step lengths were also acquired during the field campaign

Combined MIPAS (airborne/satellite), CALIPSO and in situ study on large potential NAT particles observed in early Arctic winter stratosphere in December 2011

NASA Astrophysics Data System (ADS)

Woiwode, Wolfgang; Höpfner, Michael; Pitts, Michael; Poole, Lamont; Oelhaf, Hermann; Molleker, Sergej; Borrmann, Stephan; Ebersoldt, Andreas; Frey, Wiebke; Gulde, Thomas; Maucher, Guido; Piesch, Christof; Sartorius, Christian; Orphal, Johannes

2015-04-01

The understanding of the characteristics of large HNO3-containing particles (potential 'NAT-rocks') involved in vertical redistribution of HNO3 in the polar winter stratosphere is limited due to the difficult accessibility of these particles by observations. While robust polar stratospheric cloud (PSC) classification schemes exist for observations by the space-borne lidar aboard CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) as well as for the passive mid-infrared limb observations by MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), these observations are hardly exploited for the detection of large (diameter >10 μm) NAT particles. This is due to the facts that these particles have low overall number densities, resulting in weak detectable signatures, and that the physical characteristics of these particles (i.e. shape, morphology, HNO3-content and optical characteristics) are uncertain. We investigate collocated and complementary observations of a low-density potential large NAT particle field by the space-borne instruments CALIPSO and MIPAS-ENVISAT as well as the airborne observations by the limb-sounder MIPAS-STR and the in situ particle probe FSSP-100 (Forward Scattering Spectrometer Probe 100) aboard the high-altitude aircraft Geophysica. The observations aboard the Geophysica on 11 December 2011 associated to ESSenCe (ESa Sounder Campaign 2011) provided us the unique opportunity to study in detail the lower boundary region of a PSC where large potential NAT particles (>20 μm in diameter) were detected in situ. We analyse the ambient temperatures and gas-phase composition (HNO3 and H2O), the signatures of the observed particles in the CALIPSO and MIPAS observations, the HNO3-content of these particles suggested by the FSSP-100 and MIPAS-STR observations, and focus on the spectral fingerprint of these particles in the MIPAS-STR observations. While the spectral characterisation of the observed particles is subject

Particle astronomy and particle physics from the moon - The particle observatory

NASA Technical Reports Server (NTRS)

Wilson, Thomas L.

1990-01-01

Promising experiments from the moon using particle detectors are discussed, noting the advantage of the large flux collecting power Pc offered by the remote, stable environment of a lunar base. An observatory class of particle experiments is presented, based upon proposals at NASA's recent Stanford workshop. They vary from neutrino astronomy, particle astrophysics, and cosmic ray experiments to space physics and fundamental physics experiments such as proton decay and 'table-top' arrays. This research is background-limited on earth, and it is awkward and unrealistic in earth orbit, but is particularly suited for the moon where Pc can be quite large and the instrumentation is not subject to atmospheric erosion as it is (for large t) in low earth orbit.

Collision of large dust particles with Suisei spacecraft

NASA Astrophysics Data System (ADS)

Uesugi, K.

1986-12-01

The spacecraft Suisei encountered Halley's comet at 13:05:49 UT on March 8, 1986. The closest approach distance to the comet was 151,000 km and during the time of closest approach, Suisei was hit twice by dust particles which were believed to come from the comet nucleus. Although Suisei has no dust counter or detector, the mass of these particles can be estimated by the analysis of attitude change of the spin-stabilized spacecraft perturbed by the collisions. The result shows that the minimum weight of the first particle should be several milligram and second one was several ten micrograms.

Particle formation induced by sonication during yogurt fermentation - Impact of exopolysaccharide-producing starter cultures on physical properties.

PubMed

Körzendörfer, Adrian; Nöbel, Stefan; Hinrichs, Jörg

2017-07-01

Two major quality defects of yogurt are syneresis and the presence of large particles, and several reasons have been extensively discussed. Vibrations during fermentation, particularly generated by pumps, must be considered as a further cause as latest research showed that both ultrasound and low frequencies induced visible particles. The aim of this study was to investigate the impact of sonication during fermentation with starter cultures differing in exopolysaccharide (EPS) synthesis on the physical properties of set (syneresis, firmness) and stirred yogurt (large particles, laser diffraction, rheology). Skim milk was fermented with starter cultures YC-471 (low EPS) or YF-L 901 (high EPS) (Chr. Hansen) and sonicated for 5min at pH5.2. Sonicated set gels exhibited syneresis and were softer than respective controls. The mechanical treatment was adjusted to quantify visible particles (d≥0.9mm) in stirred yogurts properly. Sonication significantly increased particle numbers, however, the effect was less pronounced when YF-L 901 was used, indicating EPS as a tool to reduce syneresis and particle formation due to vibrations. Rheological parameters and size of microgel particles were rather influenced by starter cultures than by sonication. Copyright © 2017 Elsevier Ltd. All rights reserved.

Demonstrating the feasibility of large-scale development of standardized assays to quantify human proteins

PubMed Central

Kennedy, Jacob J.; Abbatiello, Susan E.; Kim, Kyunggon; Yan, Ping; Whiteaker, Jeffrey R.; Lin, Chenwei; Kim, Jun Seok; Zhang, Yuzheng; Wang, Xianlong; Ivey, Richard G.; Zhao, Lei; Min, Hophil; Lee, Youngju; Yu, Myeong-Hee; Yang, Eun Gyeong; Lee, Cheolju; Wang, Pei; Rodriguez, Henry; Kim, Youngsoo; Carr, Steven A.; Paulovich, Amanda G.

2014-01-01

The successful application of MRM in biological specimens raises the exciting possibility that assays can be configured to measure all human proteins, resulting in an assay resource that would promote advances in biomedical research. We report the results of a pilot study designed to test the feasibility of a large-scale, international effort in MRM assay generation. We have configured, validated across three laboratories, and made publicly available as a resource to the community 645 novel MRM assays representing 319 proteins expressed in human breast cancer. Assays were multiplexed in groups of >150 peptides and deployed to quantify endogenous analyte in a panel of breast cancer-related cell lines. Median assay precision was 5.4%, with high inter-laboratory correlation (R2 >0.96). Peptide measurements in breast cancer cell lines were able to discriminate amongst molecular subtypes and identify genome-driven changes in the cancer proteome. These results establish the feasibility of a scaled, international effort. PMID:24317253

Characterizing and quantifying superparamagnetic magnetite particles in serpentinized mantle peridotite observed in continental ophiolite complexes.

NASA Astrophysics Data System (ADS)

Ortiz, E.; Vento, N. F. R.; Tominaga, M.; Beinlich, A.; Einsle, J. F.; Buisman, I.; Ringe, E.; Schrenk, M. O.; Cardace, D.

2017-12-01

Serpentinization of mantle peridotite has been recognized as one of the most important energy factories for the deep biosphere. To better evaluate the habitability of the deep biosphere, it is crucial to understand the link between in situ peridotite serpentinization processes and associated magnetite and hydrogen production. Previous efforts in correlating magnetite and hydrogen production during serpentinization processes are based primarily on laboratory experiments and numerical modeling, being challenged to include the contribution of superparamagnetic-sized magnetites (i.e., extremely fine-grained magnetite, petrographically observed as a "pepper flake" like texture in many natural serpentinized rock samples). To better estimate the abundance of superparamagnetic grains, we conducted frequency-dependent susceptibility magnetic measurements at the Institute of Rock Magnetism on naturally serpentinized rock samples from the Coast Range Ophiolite Microbial Observatory (CROMO) in California, USA and the Atlin Ophiolite (British Columbia). In addition, we conducted multiscale EDS phase mapping, BackScattered Electron (BSE) scanning, FIB-nanotomography and STEM-EELS to identify and quantify the superparamagnetic minerals that contribute to the measured magnetic susceptibility signals in our rock samples. Utilizing a multidisciplinary approach, we aim to improve the estimation of hydrogen production based on the abundance of magnetite, that includes the contribution of superparamagnetic particle size magnetite, to ultimately provide a more accurate estimation of bulk deep-biomass hosted by in situ serpentinization processes.

Implementation Strategies for Large-Scale Transport Simulations Using Time Domain Particle Tracking

NASA Astrophysics Data System (ADS)

Painter, S.; Cvetkovic, V.; Mancillas, J.; Selroos, J.

2008-12-01

Time domain particle tracking is an emerging alternative to the conventional random walk particle tracking algorithm. With time domain particle tracking, particles are moved from node to node on one-dimensional pathways defined by streamlines of the groundwater flow field or by discrete subsurface features. The time to complete each deterministic segment is sampled from residence time distributions that include the effects of advection, longitudinal dispersion, a variety of kinetically controlled retention (sorption) processes, linear transformation, and temporal changes in groundwater velocities and sorption parameters. The simulation results in a set of arrival times at a monitoring location that can be post-processed with a kernel method to construct mass discharge (breakthrough) versus time. Implementation strategies differ for discrete flow (fractured media) systems and continuous porous media systems. The implementation strategy also depends on the scale at which hydraulic property heterogeneity is represented in the supporting flow model. For flow models that explicitly represent discrete features (e.g., discrete fracture networks), the sampling of residence times along segments is conceptually straightforward. For continuous porous media, such sampling needs to be related to the Lagrangian velocity field. Analytical or semi-analytical methods may be used to approximate the Lagrangian segment velocity distributions in aquifers with low-to-moderate variability, thereby capturing transport effects of subgrid velocity variability. If variability in hydraulic properties is large, however, Lagrangian velocity distributions are difficult to characterize and numerical simulations are required; in particular, numerical simulations are likely to be required for estimating the velocity integral scale as a basis for advective segment distributions. Aquifers with evolving heterogeneity scales present additional challenges. Large-scale simulations of radionuclide

Understanding and Quantifying the Reactivity of Energetic NanoParticles and NanoComposites

DTIC Science & Technology

2015-01-05

Aerosol Synthesis and Reactivity of Thin Oxide Shell Aluminum Nanoparticles via Fluorocarboxylic Acid Functional Coating, Particle & Particle...Received Paper 3.00 9.00 8.00 7.00 6.00 5.00 4.00 X. Ma and M.R. Zachariah. " Oxidation Anisotropy and Size Dependent Reaction Kinetics of Zinc ...in the reaction. Experiments also conducted for neat Al, CuO, Fe2O3 and ZnO powders show that the oxygen are produced by decomposition of oxidizer

Study of aluminum particle combustion in solid propellant plumes using digital in-line holography and imaging pyrometry

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

Chen, Yi; Guildenbecher, Daniel R.; Hoffmeister, Kathryn N. G.

The combustion of molten metals is an important area of study with applications ranging from solid aluminized rocket propellants to fireworks displays. Our work uses digital in-line holography (DIH) to experimentally quantify the three-dimensional position, size, and velocity of aluminum particles during combustion of ammonium perchlorate (AP) based solid-rocket propellants. Additionally, spatially resolved particle temperatures are simultaneously measured using two-color imaging pyrometry. To allow for fast characterization of the properties of tens of thousands of particles, automated data processing routines are proposed. In using these methods, statistics from aluminum particles with diameters ranging from 15 to 900 µm are collectedmore » at an ambient pressure of 83 kPa. In the first set of DIH experiments, increasing initial propellant temperature is shown to enhance the agglomeration of nascent aluminum at the burning surface, resulting in ejection of large molten aluminum particles into the exhaust plume. The resulting particle number and volume distributions are quantified. In the second set of simultaneous DIH and pyrometry experiments, particle size and velocity relationships as well as temperature statistics are explored. The average measured temperatures are found to be 2640 ± 282 K, which compares well with previous estimates of the range of particle and gas-phase temperatures. The novel methods proposed here represent new capabilities for simultaneous quantification of the joint size, velocity, and temperature statistics during the combustion of molten metal particles. The proposed techniques are expected to be useful for detailed performance assessment of metalized solid-rocket propellants.« less

Study of aluminum particle combustion in solid propellant plumes using digital in-line holography and imaging pyrometry

DOE PAGES

Chen, Yi; Guildenbecher, Daniel R.; Hoffmeister, Kathryn N. G.; ...

2017-05-05

The combustion of molten metals is an important area of study with applications ranging from solid aluminized rocket propellants to fireworks displays. Our work uses digital in-line holography (DIH) to experimentally quantify the three-dimensional position, size, and velocity of aluminum particles during combustion of ammonium perchlorate (AP) based solid-rocket propellants. Additionally, spatially resolved particle temperatures are simultaneously measured using two-color imaging pyrometry. To allow for fast characterization of the properties of tens of thousands of particles, automated data processing routines are proposed. In using these methods, statistics from aluminum particles with diameters ranging from 15 to 900 µm are collectedmore » at an ambient pressure of 83 kPa. In the first set of DIH experiments, increasing initial propellant temperature is shown to enhance the agglomeration of nascent aluminum at the burning surface, resulting in ejection of large molten aluminum particles into the exhaust plume. The resulting particle number and volume distributions are quantified. In the second set of simultaneous DIH and pyrometry experiments, particle size and velocity relationships as well as temperature statistics are explored. The average measured temperatures are found to be 2640 ± 282 K, which compares well with previous estimates of the range of particle and gas-phase temperatures. The novel methods proposed here represent new capabilities for simultaneous quantification of the joint size, velocity, and temperature statistics during the combustion of molten metal particles. The proposed techniques are expected to be useful for detailed performance assessment of metalized solid-rocket propellants.« less

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.

Particle Sizer

NASA Technical Reports Server (NTRS)

1987-01-01

Microspheres are tiny plastic beads that represent the first commercial products manufactured in orbit. An example of how they are used is a new aerodynamic particle sizer designated APS 33B produced by TSI Incorporated. TSI purchased the microspheres from the National Bureau of Standards which certified their exact size and the company uses them in calibration of the APS 33B* instrument, latest in a line of TSI systems for generating counting and weighing minute particles of submicron size. Instruments are used for evaluating air pollution control devices, quantifying environments, meteorological research, testing filters, inhalation, toxicology and other areas where generation or analysis of small airborne particles is required. * The APS 33B is no longer being manufactured. An improved version, APS 3320, is now being manufactured. 2/28/97

Composition variations of low energy heavy ions during large solar energetic particle events

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

Ho, George C., E-mail: George.Ho@jhuapl.edu; Mason, Glenn M., E-mail: Glenn.Mason@jhuapl.edu

2016-03-25

The time-intensity profile of large solar energetic particle (SEP) event is well organized by solar longitude as observed at Earth orbit. This is mostly due to different magnetic connection to the shock that is associated with large SEP event propagates from the Sun to the heliosphere. Earlier studies have shown event averaged heavy ion abundance ratios can also vary as a function of solar longitude. It was found that the Fe/O ratio for high energy particle (>10 MeV/nucleon) is higher for those western magnetically well connected events compare to the eastern events as observed at L1 by the Advanced Composition Explorermore » (ACE) spacecraft. In this paper, we examined the low energy (∼1 MeV/nucleon) heavy ions in 110 isolated SEP events from 2009 to the end of 2014. In addition, the optical and radio signatures for all of our events are identified and when data are available we also located the associated coronal mass ejection (CME) data. Our survey shows a higher Fe/O ratio at events in the well-connected region, while there are no corrections between the event averaged elemental composition with the associated coronal mass ejection speed. This is inconsistent with the higher energy results, but inline with other recent low-energy measurements.« less

Production of large-particle-size monodisperse latexes

NASA Technical Reports Server (NTRS)

Vanderhoff, J. W.; El-Aasser, M. L.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.

1984-01-01

The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.

A New Approach to Quantify Shallow Water Hydrologic Exchanges in a Large Regulated River Reach

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

Zhou, Tian; Huang, Maoyi; Bao, Jie

Hyporheic exchange is a crucial component in the water cycle. The strength of the exchange directly affects the biogeochemical and ecological processes occurred in the hyporheic zone from micro to reach scale. Hyporheic fluxes can be quantified using many direct and indirect measurements as well as analytical and numerical modeling tools. However, in a relatively large river, these methods are limited by accessibility, the difficulty of performing representative sampling, and complexity of geomorphologic features and subsurface properties. In rivers regulated by hydroelectric dams, quantifying hyporheic fluxes becomes more challenging due to frequent hydropeaking events, featured by hourly to daily variationsmore » in flow and river stages created by dam operations(Hancock 2002). In this study, we developed and validated methods that based on field measurements to estimate shallow water hyporheic fluxes across the river bed at five locations along the shoreline of the Columbia River. Vertical thermal profiles measured by self-recording thermistors were combined with time series of hydraulic gradients derived from river stage and water level at in-land wells to estimate the hyporheic flux rate. The results suggested that the hyporheic exchange rate had high spatial and temporal heterogeneities over the riverbed, with predicted flux rate varies from +1×10 -6 m s-1 to -1.5×10 -6 m s -1 under various flow conditions at the some locations, and with a magnitude of fluxes 6-9 times higher in the primary channel than that in the secondary channel. Furthermore, the variations on shallow water hyporheic flow dynamics may further lead to different biogeochemical and ecological consequences at different river segments.« less

A New Approach to Quantify Shallow Water Hydrologic Exchanges in a Large Regulated River Reach

DOE PAGES

Zhou, Tian; Huang, Maoyi; Bao, Jie; ...

2017-09-15

Hyporheic exchange is a crucial component in the water cycle. The strength of the exchange directly affects the biogeochemical and ecological processes occurred in the hyporheic zone from micro to reach scale. Hyporheic fluxes can be quantified using many direct and indirect measurements as well as analytical and numerical modeling tools. However, in a relatively large river, these methods are limited by accessibility, the difficulty of performing representative sampling, and complexity of geomorphologic features and subsurface properties. In rivers regulated by hydroelectric dams, quantifying hyporheic fluxes becomes more challenging due to frequent hydropeaking events, featured by hourly to daily variationsmore » in flow and river stages created by dam operations(Hancock 2002). In this study, we developed and validated methods that based on field measurements to estimate shallow water hyporheic fluxes across the river bed at five locations along the shoreline of the Columbia River. Vertical thermal profiles measured by self-recording thermistors were combined with time series of hydraulic gradients derived from river stage and water level at in-land wells to estimate the hyporheic flux rate. The results suggested that the hyporheic exchange rate had high spatial and temporal heterogeneities over the riverbed, with predicted flux rate varies from +1×10 -6 m s-1 to -1.5×10 -6 m s -1 under various flow conditions at the some locations, and with a magnitude of fluxes 6-9 times higher in the primary channel than that in the secondary channel. Furthermore, the variations on shallow water hyporheic flow dynamics may further lead to different biogeochemical and ecological consequences at different river segments.« less

Chirping and Sudden Excitation of Energetic-Particle-Driven Geodesic Acoustic Modes in a Large Helical Device Experiment

NASA Astrophysics Data System (ADS)

Wang, Hao; Todo, Yasushi; Ido, Takeshi; Suzuki, Yasuhiro

2018-04-01

Energetic-particle-driven geodesic acoustic modes (EGAMs) observed in a Large Helical Device experiment are investigated using a hybrid simulation code for energetic particles interacting with a magnetohydrodynamic (MHD) fluid. The frequency chirping of the primary mode and the sudden excitation of the half-frequency secondary mode are reproduced for the first time with the hybrid simulation using the realistic physical condition and the three-dimensional equilibrium. Both EGAMs have global spatial profiles which are consistent with the experimental measurements. For the secondary mode, the bulk pressure perturbation and the energetic particle pressure perturbation cancel each other out, and thus the frequency is lower than the primary mode. It is found that the excitation of the secondary mode does not depend on the nonlinear MHD coupling. The secondary mode is excited by energetic particles that satisfy the linear and nonlinear resonance conditions, respectively, for the primary and secondary modes.

Chirping and Sudden Excitation of Energetic-Particle-Driven Geodesic Acoustic Modes in a Large Helical Device Experiment.

PubMed

Wang, Hao; Todo, Yasushi; Ido, Takeshi; Suzuki, Yasuhiro

2018-04-27

Energetic-particle-driven geodesic acoustic modes (EGAMs) observed in a Large Helical Device experiment are investigated using a hybrid simulation code for energetic particles interacting with a magnetohydrodynamic (MHD) fluid. The frequency chirping of the primary mode and the sudden excitation of the half-frequency secondary mode are reproduced for the first time with the hybrid simulation using the realistic physical condition and the three-dimensional equilibrium. Both EGAMs have global spatial profiles which are consistent with the experimental measurements. For the secondary mode, the bulk pressure perturbation and the energetic particle pressure perturbation cancel each other out, and thus the frequency is lower than the primary mode. It is found that the excitation of the secondary mode does not depend on the nonlinear MHD coupling. The secondary mode is excited by energetic particles that satisfy the linear and nonlinear resonance conditions, respectively, for the primary and secondary modes.

Separating large microscale particles by exploiting charge differences with dielectrophoresis.

PubMed

Polniak, Danielle V; Goodrich, Eric; Hill, Nicole; Lapizco-Encinas, Blanca H

2018-04-13

Dielectrophoresis (DEP), the migration of particles due to polarization effects under the influence of a nonuniform electric field, was employed for characterizing the behavior and achieving the separation of larger (diameter >5 μm) microparticles by exploiting differences in electrical charge. Usually, electrophoresis (EP) is the method of choice for separating particles based on differences in electrical charge; however, larger particles, which have low electrophoretic mobilities, cannot be easily separated with EP-based techniques. This study presents an alternative for the characterization, assessment, and separation of larger microparticles, where charge differences are exploited with DEP instead of EP. Polystyrene microparticles with sizes varying from 5 to 10 μm were characterized employing microdevices for insulator-based dielectrophoresis (iDEP). Particles within an iDEP microchannel were exposed simultaneously to DEP, EP, and electroosmotic (EO) forces. The electrokinetic behavior of four distinct types of microparticles was carefully characterized by means of velocimetry and dielectrophoretic capture assessments. As a final step, a dielectropherogram separation of two distinct types of 10 μm particles was devised by first characterizing the particles and then performing the separation. The two types of 10 μm particles were eluted from the iDEP device as two separate peaks of enriched particles in less than 80 s. It was demonstrated that particles with the same size, shape, surface functionalization, and made from the same bulk material can be separated with iDEP by exploiting slight differences in the magnitude of particle charge. The results from this study open the possibility for iDEP to be used as a technique for the assessment and separation of biological cells that have very similar characteristics (shape, size, similar make-up), but slight variance in surface electrical charge. Copyright © 2018 Elsevier B.V. All rights reserved.

Simulation of large particle transport near the surface under stable conditions: comparison with the Hanford tracer experiments

NASA Astrophysics Data System (ADS)

Kim, Eugene; Larson, Timothy

A plume model is presented describing the downwind transport of large particles (1-100 μm) under stable conditions. The model includes both vertical variations in wind speed and turbulence intensity as well as an algorithm for particle deposition at the surface. Model predictions compare favorably with the Hanford single and dual tracer experiments of crosswind integrated concentration (for particles: relative bias=-0.02 and 0.16, normalized mean square error=0.61 and 0.14, for the single and dual tracer experiments, respectively), whereas the US EPA's fugitive dust model consistently overestimates the observed concentrations at downwind distances beyond several hundred meters (for particles: relative bias=0.31 and 2.26, mean square error=0.42 and 1.71, respectively). For either plume model, the measured ratio of particle to gas concentration is consistently overestimated when using the deposition velocity algorithm of Sehmel and Hodgson (1978. DOE Report PNL-SA-6721, Pacific Northwest Laboratories, Richland, WA). In contrast, these same ratios are predicted with relatively little bias when using the algorithm of Kim et al. (2000. Atmospheric Environment 34 (15), 2387-2397).

Ultrasensitive multiplex optical quantification of bacteria in large samples of biofluids

PubMed Central

Pazos-Perez, Nicolas; Pazos, Elena; Catala, Carme; Mir-Simon, Bernat; Gómez-de Pedro, Sara; Sagales, Juan; Villanueva, Carlos; Vila, Jordi; Soriano, Alex; García de Abajo, F. Javier; Alvarez-Puebla, Ramon A.

2016-01-01

Efficient treatments in bacterial infections require the fast and accurate recognition of pathogens, with concentrations as low as one per milliliter in the case of septicemia. Detecting and quantifying bacteria in such low concentrations is challenging and typically demands cultures of large samples of blood (~1 milliliter) extending over 24–72 hours. This delay seriously compromises the health of patients. Here we demonstrate a fast microorganism optical detection system for the exhaustive identification and quantification of pathogens in volumes of biofluids with clinical relevance (~1 milliliter) in minutes. We drive each type of bacteria to accumulate antibody functionalized SERS-labelled silver nanoparticles. Particle aggregation on the bacteria membranes renders dense arrays of inter-particle gaps in which the Raman signal is exponentially amplified by several orders of magnitude relative to the dispersed particles. This enables a multiplex identification of the microorganisms through the molecule-specific spectral fingerprints. PMID:27364357

Identifying and quantifying interactions in a laboratory swarm

NASA Astrophysics Data System (ADS)

Puckett, James; Kelley, Douglas; Ouellette, Nicholas

2013-03-01

Emergent collective behavior, such as in flocks of birds or swarms of bees, is exhibited throughout the animal kingdom. Many models have been developed to describe swarming and flocking behavior using systems of self-propelled particles obeying simple rules or interacting via various potentials. However, due to experimental difficulties and constraints, little empirical data exists for characterizing the exact form of the biological interactions. We study laboratory swarms of flying Chironomus riparius midges, using stereoimaging and particle tracking techniques to record three-dimensional trajectories for all the individuals in the swarm. We describe methods to identify and quantify interactions by examining these trajectories, and report results on interaction magnitude, frequency, and mutuality.

Direct Measurements of Gas/Particle Partitioning and Mass Accommodation Coefficients in Environmental Chambers.

PubMed

Krechmer, Jordan E; Day, Douglas A; Ziemann, Paul J; Jimenez, Jose L

2017-10-17

Secondary organic aerosols (SOA) are a major contributor to fine particulate mass and wield substantial influences on the Earth's climate and human health. Despite extensive research in recent years, many of the fundamental processes of SOA formation and evolution remain poorly understood. Most atmospheric aerosol models use gas/particle equilibrium partitioning theory as a default treatment of gas-aerosol transfer, despite questions about potentially large kinetic effects. We have conducted fundamental SOA formation experiments in a Teflon environmental chamber using a novel method. A simple chemical system produces a very fast burst of low-volatility gas-phase products, which are competitively taken up by liquid organic seed particles and Teflon chamber walls. Clear changes in the species time evolution with differing amounts of seed allow us to quantify the particle uptake processes. We reproduce gas- and aerosol-phase observations using a kinetic box model, from which we quantify the aerosol mass accommodation coefficient (α) as 0.7 on average, with values near unity especially for low volatility species. α appears to decrease as volatility increases. α has historically been a very difficult parameter to measure with reported values varying over 3 orders of magnitude. We use the experimentally constrained model to evaluate the correction factor (Φ) needed for chamber SOA mass yields due to losses of vapors to walls as a function of species volatility and particle condensational sink. Φ ranges from 1-4.

The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet

USGS Publications Warehouse

Erikson, Li H.; Wright, Scott A.; Elias, Edwin; Hanes, Daniel M.; Schoellhamer, David H.; Largier, John; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

Sediment exchange at large energetic inlets is often difficult to quantify due complex flows, massive amounts of water and sediment exchange, and environmental conditions limiting long-term data collection. In an effort to better quantify such exchange this study investigated the use of suspended sediment concentrations (SSC) measured at an offsite location as a surrogate for sediment exchange at the tidally dominated Golden Gate inlet in San Francisco, CA. A numerical model was calibrated and validated against water and suspended sediment flux measured during a spring–neap tide cycle across the Golden Gate. The model was then run for five months and net exchange was calculated on a tidal time-scale and compared to SSC measurements at the Alcatraz monitoring site located in Central San Francisco Bay ~ 5 km from the Golden Gate. Numerically modeled tide averaged flux across the Golden Gate compared well (r2 = 0.86, p-value

Quantifying primary and secondary source contributions to ultrafine particles in the UK urban background

NASA Astrophysics Data System (ADS)

Hama, S. M. L.; Cordell, R. L.; Monks, P. S.

2017-10-01

Total particle number (TNC, ≥7 nm diameter), particulate matter (PM2.5), equivalent black carbon (eBC) and gaseous pollutants (NO, NO2, NOx, O3, CO) have been measured at an urban background site in Leicester over two years (2014 and 2015). A derived chemical climatology for the pollutants showed maximum concentrations for all pollutants during the cold period except O3 which peaked during spring. Quantification of primary and secondary sources of ultrafine particles (UFPs) was undertaken using eBC as a tracer for the primary particle number concentration in the Leicester urban area. At the urban background site, which is influenced by fresh vehicle exhaust emissions, TNC was segregated into two components, TNC = N1 + N2. The component N1 represents components directly emitted as particles and compounds which nucleate immediately after emission. The component N2 represents the particles formed during the dilution and cooling of vehicle exhaust emissions and by in situ new particle formation (NPF). The values of highest N1 (49%) were recorded during the morning rush hours (07:00-09:00 h), correlating with NOx, while the maximum contribution of N2 to TNC was found at midday (11:00-14:00 h), at around 62%, correlated with O3. Generally, the percentage of N2 (57%) was greater than the percentage of N1 (43%) for all days at the AURN site over the period of the study. For the first time the impact of wind speed and direction on N1 and N2 was explored. The overall data analysis shows that there are two major sources contributing to TNC in Leicester: primary sources (traffic emissions) and secondary sources, with the majority of particles being of secondary origin.

Uncertainty quantification in volumetric Particle Image Velocimetry

NASA Astrophysics Data System (ADS)

Bhattacharya, Sayantan; Charonko, John; Vlachos, Pavlos

2016-11-01

Particle Image Velocimetry (PIV) uncertainty quantification is challenging due to coupled sources of elemental uncertainty and complex data reduction procedures in the measurement chain. Recent developments in this field have led to uncertainty estimation methods for planar PIV. However, no framework exists for three-dimensional volumetric PIV. In volumetric PIV the measurement uncertainty is a function of reconstructed three-dimensional particle location that in turn is very sensitive to the accuracy of the calibration mapping function. Furthermore, the iterative correction to the camera mapping function using triangulated particle locations in space (volumetric self-calibration) has its own associated uncertainty due to image noise and ghost particle reconstructions. Here we first quantify the uncertainty in the triangulated particle position which is a function of particle detection and mapping function uncertainty. The location uncertainty is then combined with the three-dimensional cross-correlation uncertainty that is estimated as an extension of the 2D PIV uncertainty framework. Finally the overall measurement uncertainty is quantified using an uncertainty propagation equation. The framework is tested with both simulated and experimental cases. For the simulated cases the variation of estimated uncertainty with the elemental volumetric PIV error sources are also evaluated. The results show reasonable prediction of standard uncertainty with good coverage.

Large density expansion of a hydrodynamic theory for self-propelled particles

NASA Astrophysics Data System (ADS)

Ihle, T.

2015-07-01

Recently, an Enskog-type kinetic theory for Vicsek-type models for self-propelled particles has been proposed [T. Ihle, Phys. Rev. E 83, 030901 (2011)]. This theory is based on an exact equation for a Markov chain in phase space and is not limited to small density. Previously, the hydrodynamic equations were derived from this theory and its transport coefficients were given in terms of infinite series. Here, I show that the transport coefficients take a simple form in the large density limit. This allows me to analytically evaluate the well-known density instability of the polarly ordered phase near the flocking threshold at moderate and large densities. The growth rate of a longitudinal perturbation is calculated and several scaling regimes, including three different power laws, are identified. It is shown that at large densities, the restabilization of the ordered phase at smaller noise is analytically accessible within the range of validity of the hydrodynamic theory. Analytical predictions for the width of the unstable band, the maximum growth rate, and for the wave number below which the instability occurs are given. In particular, the system size below which spatial perturbations of the homogeneous ordered state are stable is predicted to scale with where √ M is the average number of collision partners. The typical time scale until the instability becomes visible is calculated and is proportional to M.

Spatial Variability of CCN Sized Aerosol Particles

NASA Astrophysics Data System (ADS)

Asmi, A.; Väänänen, R.

2014-12-01

The computational limitations restrict the grid size used in GCM models, and for many cloud types they are too large when compared to the scale of the cloud formation processes. Several parameterizations for e.g. convective cloud formation exist, but information on spatial subgrid variation of the cloud condensation nuclei (CCNs) sized aerosol concentration is not known. We quantify this variation as a function of the spatial scale by using datasets from airborne aerosol measurement campaigns around the world including EUCAARI LONGREX, ATAR, INCA, INDOEX, CLAIRE, PEGASOS and several regional airborne campaigns in Finland. The typical shapes of the distributions are analyzed. When possible, we use information obtained by CCN counters. In some other cases, we use particle size distribution measured by for example SMPS to get approximated CCN concentration. Other instruments used include optical particle counters or condensational particle counters. When using the GCM models, the CCN concentration used for each the grid-box is often considered to be either flat, or as an arithmetic mean of the concentration inside the grid-box. However, the aircraft data shows that the concentration values are often lognormal distributed. This, combined with the subgrid variations in the land use and atmospheric properties, might cause that the aerosol-cloud interactions calculated by using mean values to vary significantly from the true effects both temporary and spatially. This, in turn, can cause non-linear bias into the GCMs. We calculate the CCN aerosol concentration distribution as a function of different spatial scales. The measurements allow us to study the variation of these distributions within from hundreds of meters up to hundreds of kilometers. This is used to quantify the potential error when mean values are used in GCMs.

Information criteria for quantifying loss of reversibility in parallelized KMC

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

Gourgoulias, Konstantinos, E-mail: gourgoul@math.umass.edu; Katsoulakis, Markos A., E-mail: markos@math.umass.edu; Rey-Bellet, Luc, E-mail: luc@math.umass.edu

Parallel Kinetic Monte Carlo (KMC) is a potent tool to simulate stochastic particle systems efficiently. However, despite literature on quantifying domain decomposition errors of the particle system for this class of algorithms in the short and in the long time regime, no study yet explores and quantifies the loss of time-reversibility in Parallel KMC. Inspired by concepts from non-equilibrium statistical mechanics, we propose the entropy production per unit time, or entropy production rate, given in terms of an observable and a corresponding estimator, as a metric that quantifies the loss of reversibility. Typically, this is a quantity that cannot bemore » computed explicitly for Parallel KMC, which is why we develop a posteriori estimators that have good scaling properties with respect to the size of the system. Through these estimators, we can connect the different parameters of the scheme, such as the communication time step of the parallelization, the choice of the domain decomposition, and the computational schedule, with its performance in controlling the loss of reversibility. From this point of view, the entropy production rate can be seen both as an information criterion to compare the reversibility of different parallel schemes and as a tool to diagnose reversibility issues with a particular scheme. As a demonstration, we use Sandia Lab's SPPARKS software to compare different parallelization schemes and different domain (lattice) decompositions.« less

Information criteria for quantifying loss of reversibility in parallelized KMC

NASA Astrophysics Data System (ADS)

Gourgoulias, Konstantinos; Katsoulakis, Markos A.; Rey-Bellet, Luc

2017-01-01

Parallel Kinetic Monte Carlo (KMC) is a potent tool to simulate stochastic particle systems efficiently. However, despite literature on quantifying domain decomposition errors of the particle system for this class of algorithms in the short and in the long time regime, no study yet explores and quantifies the loss of time-reversibility in Parallel KMC. Inspired by concepts from non-equilibrium statistical mechanics, we propose the entropy production per unit time, or entropy production rate, given in terms of an observable and a corresponding estimator, as a metric that quantifies the loss of reversibility. Typically, this is a quantity that cannot be computed explicitly for Parallel KMC, which is why we develop a posteriori estimators that have good scaling properties with respect to the size of the system. Through these estimators, we can connect the different parameters of the scheme, such as the communication time step of the parallelization, the choice of the domain decomposition, and the computational schedule, with its performance in controlling the loss of reversibility. From this point of view, the entropy production rate can be seen both as an information criterion to compare the reversibility of different parallel schemes and as a tool to diagnose reversibility issues with a particular scheme. As a demonstration, we use Sandia Lab's SPPARKS software to compare different parallelization schemes and different domain (lattice) decompositions.

Line-Scanning Particle Image Velocimetry: An Optical Approach for Quantifying a Wide Range of Blood Flow Speeds in Live Animals

PubMed Central

Kim, Tyson N.; Goodwill, Patrick W.; Chen, Yeni; Conolly, Steven M.; Schaffer, Chris B.; Liepmann, Dorian; Wang, Rong A.

2012-01-01

Background The ability to measure blood velocities is critical for studying vascular development, physiology, and pathology. A key challenge is to quantify a wide range of blood velocities in vessels deep within living specimens with concurrent diffraction-limited resolution imaging of vascular cells. Two-photon laser scanning microscopy (TPLSM) has shown tremendous promise in analyzing blood velocities hundreds of micrometers deep in animals with cellular resolution. However, current analysis of TPLSM-based data is limited to the lower range of blood velocities and is not adequate to study faster velocities in many normal or disease conditions. Methodology/Principal Findings We developed line-scanning particle image velocimetry (LS-PIV), which used TPLSM data to quantify peak blood velocities up to 84 mm/s in live mice harboring brain arteriovenous malformation, a disease characterized by high flow. With this method, we were able to accurately detect the elevated blood velocities and exaggerated pulsatility along the abnormal vascular network in these animals. LS-PIV robustly analyzed noisy data from vessels as deep as 850 µm below the brain surface. In addition to analyzing in vivo data, we validated the accuracy of LS-PIV up to 800 mm/s using simulations with known velocity and noise parameters. Conclusions/Significance To our knowledge, these blood velocity measurements are the fastest recorded with TPLSM. Partnered with transgenic mice carrying cell-specific fluorescent reporters, LS-PIV will also enable the direct in vivo correlation of cellular, biochemical, and hemodynamic parameters in high flow vascular development and diseases such as atherogenesis, arteriogenesis, and vascular anomalies. PMID:22761686

Motions of charged particles in the Magnetosphere under the influence of a time-varying large scale convection electric field

NASA Technical Reports Server (NTRS)

Smith, P. H.; Bewtra, N. K.; Hoffman, R. A.

1979-01-01

The motions of charged particles under the influence of the geomagnetic and electric fields were quite complex in the region of the inner magnetosphere. The Volland-Stern type large scale convection electric field was used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 measurements. A time dependence in this electric field was introduced based on the variation in Kp for actual magnetic storm conditions. The particle trajectories were computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments were allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format.

Dealloyed Intra-Nanogap Particles with Highly Robust, Quantifiable Surface-Enhanced Raman Scattering Signals for Biosensing and Bioimaging Applications

PubMed Central

2018-01-01

Uniformly controlling a large number of metal nanostructures with a plasmonically enhanced signal to generate quantitative optical signals and the widespread use of these structures for surface-enhanced Raman scattering (SERS)-based biosensing and bioimaging applications are of paramount importance but are extremely challenging. Here, we report a highly controllable, facile selective-interdiffusive dealloying chemistry for synthesizing the dealloyed intra-nanogap particles (DIPs) with a ∼2 nm intragap in a high yield (∼95%) without the need for an interlayer. The SERS signals from DIPs are highly quantitative and polarization-independent with polarized laser sources. Remarkably, all the analyzed particles displayed the SERS enhancement factors (EFs) of ≥1.1 × 108 with a very narrow distribution of EFs. Finally, we show that DIPs can be used as ultrasensitive SERS-based DNA detection probes for detecting 10 aM to 1 pM target concentrations and highly robust, quantitative real-time cell imaging probes for long-term imaging with low laser power and short exposure time. PMID:29532028

The application of the large particles method of numerical modeling of the process of carbonic nanostructures synthesis in plasma

NASA Astrophysics Data System (ADS)

Abramov, G. V.; Gavrilov, A. N.

2018-03-01

The article deals with the numerical solution of the mathematical model of the particles motion and interaction in multicomponent plasma by the example of electric arc synthesis of carbon nanostructures. The high order of the particles and the number of their interactions requires a significant input of machine resources and time for calculations. Application of the large particles method makes it possible to reduce the amount of computation and the requirements for hardware resources without affecting the accuracy of numerical calculations. The use of technology of GPGPU parallel computing using the Nvidia CUDA technology allows organizing all General purpose computation on the basis of the graphical processor graphics card. The comparative analysis of different approaches to parallelization of computations to speed up calculations with the choice of the algorithm in which to calculate the accuracy of the solution shared memory is used. Numerical study of the influence of particles density in the macro particle on the motion parameters and the total number of particle collisions in the plasma for different modes of synthesis has been carried out. The rational range of the coherence coefficient of particle in the macro particle is computed.

Critical conditions for particle motion in coarse bed materials of nonuniform size distribution

NASA Astrophysics Data System (ADS)

Bathurst, James C.

2013-09-01

Initiation of particle motion in a bed material of nonuniform size distribution may be quantified by (qci/qcr) = (Di/Dr)b, where qci is the critical unit discharge at which particle size Di enters motion, qcr is the critical condition for a reference size Dr unaffected by the hiding/exposure effects associated with nonuniform size distributions, i and r refer to percentiles of the distribution and b varies from 0 (equal mobility in entrainment of all particle sizes) to 1.5-2.5 (full size selective transport). Currently there is no generally accepted method for predicting the value of b. Flume and field data are therefore combined to investigate the above relationship. Thirty-seven sets of flume data quantify the relationship between critical unit discharge and particle size for bed materials with uniform size distributions (used here to approximate full size selective transport). Field data quantify the relationship for bed materials of nonuniform size distribution at 24 sites, with b ranging from 0.15 to 1.3. Intersection of the two relationships clearly demonstrates the hiding/exposure effect; in some but not all cases, Dr is close to the median size D50. The exponent has two clusters of values: b > 1 for sites subject to episodic rain-fed floods and data collected by bedload pit trap and tracers; and b < 0.7 for sites with seasonal snowmelt/glacial melt flow regimes and data collected by bedload sampler and large aperture trap. Field technique appears unlikely to cause variations in b of more than about 0.25. However, the clustering is consistent with possible variations in bed structure distinguishing: for b > 1, sites with relatively infrequent bedload transport where particle embedding and consolidation could reduce the mobility of coarser particles; and, for b < 0.7, a looser bed structure with frequent transport events allowing hiding/exposure and size selection effects to achieve their balance. As yet there is no firm evidence for such a dependency on bed

Physical-geometric optics method for large size faceted particles.

PubMed

Sun, Bingqiang; Yang, Ping; Kattawar, George W; Zhang, Xiaodong

2017-10-02

A new physical-geometric optics method is developed to compute the single-scattering properties of faceted particles. It incorporates a general absorption vector to accurately account for inhomogeneous wave effects, and subsequently yields the relevant analytical formulas effective and computationally efficient for absorptive scattering particles. A bundle of rays incident on a certain facet can be traced as a single beam. For a beam incident on multiple facets, a systematic beam-splitting technique based on computer graphics is used to split the original beam into several sub-beams so that each sub-beam is incident only on an individual facet. The new beam-splitting technique significantly reduces the computational burden. The present physical-geometric optics method can be generalized to arbitrary faceted particles with either convex or concave shapes and with a homogeneous or an inhomogeneous (e.g., a particle with a core) composition. The single-scattering properties of irregular convex homogeneous and inhomogeneous hexahedra are simulated and compared to their counterparts from two other methods including a numerically rigorous method.

Large Solar Energetic Particle Events Associated With Filament Eruptions Outside Active Regions

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

2015-01-01

We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds approx. 1000 km/s) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of approx.2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ?4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

Quantifying vorticity in magnetic particle suspensions driven by symmetric and asymmetric multiaxial fields.

DOE PAGES

Martin, James E.; Solis, Kyle Jameson

2015-08-07

We recently reported two methods of inducing vigorous fluid vorticity in magnetic particle suspensions. The first method employs symmetry-breaking rational fields. These fields are comprised of two orthogonal ac components whose frequencies form a rational number and an orthogonal dc field that breaks the symmetry of the biaxial ac field to create the parity required to induce deterministic vorticity. The second method is based on rational triads, which are fields comprised of three orthogonal ac components whose frequency ratios are rational (e.g., 1 : 2 : 3). For each method a symmetry theory has been developed that enables the predictionmore » of the direction and sign of vorticity as functions of the field frequencies and phases. However, this theory has its limitations. It only applies to those particular phase angles that give rise to fields whose Lissajous plots, or principal 2-d projections thereof, have a high degree of symmetry. Nor can symmetry theory provide a measure of the magnitude of the torque density induced by the field. In this paper a functional of the multiaxial magnetic field is proposed that not only is consistent with all of the predictions of the symmetry theories, but also quantifies the torque density. This functional can be applied to fields whose Lissajous plots lack symmetry and can thus be used to predict a variety of effects and trends that cannot be predicted from the symmetry theories. These trends include the dependence of the magnitude of the torque density on the various frequency ratios, the unexpected reversal of flow with increasing dc field amplitude for certain symmetry-breaking fields, and the existence of off-axis vorticity for rational triads, such as 1 : 3 : 5, that do not have the symmetry required to analyze by symmetry theory. As a result, experimental data are given that show the degree to which this functional is successful in predicting observed trends.« less

Time Variations in Forecasts and Occurrences of Large Solar Energetic Particle Events

NASA Astrophysics Data System (ADS)

Kahler, S. W.

2015-12-01

The onsets and development of large solar energetic (E > 10 MeV) particle (SEP) events have been characterized in many studies. The statistics of SEP event onset delay times from associated solar flares and coronal mass ejections (CMEs), which depend on solar source longitudes, can be used to provide better predictions of whether a SEP event will occur following a large flare or fast CME. In addition, size distributions of peak SEP event intensities provide a means for a probabilistic forecast of peak intensities attained in observed SEP increases. SEP event peak intensities have been compared with their rise and decay times for insight into the acceleration and transport processes. These two time scales are generally treated as independent parameters describing the development of a SEP event, but we can invoke an alternative two-parameter description based on the assumption that decay times exceed rise times for all events. These two parameters, from the well known Weibull distribution, provide an event description in terms of its basic shape and duration. We apply this distribution to several large SEP events and ask what the characteristic parameters and their dependence on source longitudes can tell us about the origins of these important events.

Motions of charged particles in the magnetosphere under the influence of a time-varying large scale convection electric field

NASA Technical Reports Server (NTRS)

Smith, P. H.; Hoffman, R. A.; Bewtra, N. K.

1979-01-01

The motions of charged particles under the influence of the geomagnetic and electric fields are quite complex in the region of the inner magnetosphere. The Volland-Stern type large-scale convection electric field with gamma = 2 has been used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 (S3-A) measurements. Recently introduced into the trajectory calculations of Ejiri et al. (1978) is a time dependence in this electric field based on the variation in Kp for actual magnetic storm conditions. The particle trajectories are computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments are allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format. The local time of injection, the particle magnetic moments and the subsequent temporal history of the magnetospheric electric field play important roles in determining whether the injected particles are trapped within the ring current region or whether they are convected to regions outside the inner magnetosphere.

Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

PubMed Central

Schobesberger, Siegfried; Junninen, Heikki; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K.; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P.; Rondo, Linda; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S.; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M.; Worsnop, Douglas R.

2013-01-01

Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions. PMID:24101502

Contribution from indoor sources to particle number and mass concentrations in residential houses

NASA Astrophysics Data System (ADS)

He, Congrong; Morawska, Lidia; Hitchins, Jane; Gilbert, Dale

As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify emission characteristics of indoor particle sources in 15 houses. Submicrometer particle number and approximation of PM 2.5 concentrations were measured simultaneously for more than 48 h in the kitchen of all the houses by using a condensation particle counter (CPC) and a photometer (DustTrak), respectively. In addition, characterizations of particles resulting from cooking conducted in an identical way in all the houses were measured by using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a DustTrak. All the events of elevated particle concentrations were linked to indoor activities using house occupants diary entries, and catalogued into 21 different types of indoor activities. This enabled quantification of the effect of indoor sources on indoor particle concentrations as well as quantification of emission rates from the sources. For example, the study found that frying, grilling, stove use, toasting, cooking pizza, cooking, candle vaporizing eucalyptus oil and fan heater use, could elevate the indoor submicrometer particle number concentration levels by more than five times, while PM 2.5 concentrations could be up to 3, 30 and 90 times higher than the background levels during smoking, frying and grilling, respectively.

Quantifying spatiotemporal variability of fine particles in an urban environment using combined fixed and mobile measurements

NASA Astrophysics Data System (ADS)

Sullivan, R. C.; Pryor, S. C.

2014-06-01

Spatiotemporal variability of fine particle concentrations in Indianapolis, Indiana is quantified using a combination of high temporal resolution measurements at four fixed sites and mobile measurements with instruments attached to bicycles during transects of the city. Average urban PM2.5 concentrations are an average of ˜3.9-5.1 μg m-3 above the regional background. The influence of atmospheric conditions on ambient PM2.5 concentrations is evident with the greatest temporal variability occurring at periods of one day and 5-10 days corresponding to diurnal and synoptic meteorological processes, and lower mean wind speeds are associated with episodes of high PM2.5 concentrations. An anthropogenic signal is also evident. Higher PM2.5 concentrations coincide with morning rush hour, the frequencies of PM2.5 variability co-occur with those for carbon monoxide, and higher extreme concentrations were observed mid-week compared to weekends. On shorter time scales (

Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA

NASA Astrophysics Data System (ADS)

Antipov, S. A.; Nagaitsev, S.; Valishev, A.

2017-04-01

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually has both beneficial (improved Landau damping) and harmful properties, such as a resonant behavior and a reduction of the dynamic aperture. One of the research goals at the IOTA ring is to achieve a large betatron tune spread, while retaining a large dynamic aperture, using conventional octupole magnets in a special but realistic accelerator configuration. The configuration, although not integrable by design, approximates an autonomous 2D Hamiltonian system. In this paper, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for enhancing Landau damping in high intensity machines.

Particle Physics after the Higgs-Boson Discovery: Opportunities for the Large Hadron Collider

DOE PAGES

Quigg, Chris

2015-08-24

The first run of the Large Hadron Collider at CERN brought the discovery of the Higgs boson, an apparently elementary scalar particle with a mass of 125 GeV, the avatar of the mechanism that hides the electroweak symmetry. Then, a new round of experimentation is beginning, with the energy of the proton–proton colliding beams raised to 6.5 TeV per beam, from 4 TeV at the end of the first run. I summarize what we have learned about the Higgs boson, and calls attention to some issues that will be among our central concerns in the near future.

Exposure assessment of nano-sized and respirable particles at different workplaces

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Huang, Cheng-Yu; Chen, Sheng-Chieh; Ho, Chi-En; Huang, Cheng-Hsiung; Chen, Chun-Wan; Chang, Cheng-Ping; Tsai, Su-Jung; Ellenbecker, Michael J.

2011-09-01

In this study, nanoparticle (NP, diameter < 100 nm) and respirable particles measurements were conducted at three different nanopowder workplaces, including the mixing area of a nano-SiO2-epoxy molding compound plant (primary diameter: 15 nm), bagging areas of a nano-carbon black (nano-CB) (primary diameter: 32 nm) and a nano-CaCO3 (primary diameter: 94 nm) manufacturing plant. Chemical analysis of respirable particle mass (RPM) and NPs was performed to quantify the content of manufactured nanoparticles in the collected samples. Nanopowder products obtained from the plants were used in the laboratory dustiness testing using a rotating drum tester to obtain particle mass and number distributions. The obtained laboratory data were then used to elucidate the field data. Both field and laboratory data showed that NP number and mass concentrations of manufactured materials were close to the background level. Number concentration was elevated only for particles with the electrical mobility diameter >100 nm during bagging or feeding processes, unless there were combustion-related incidental sources existed. Large fraction of nanomaterials was found in the RPM due to agglomeration of nanomaterials or attachment of nanomaterials to the larger particles. From this study, it is concluded that RPM concentration measurements are necessary for the exposure assessment of nanoparticles in workplaces.

Measurements of Ultra-fine and Fine Aerosol Particles over Siberia: Large-scale Airborne Campaigns

NASA Astrophysics Data System (ADS)

Arshinov, Mikhail; Paris, Jean-Daniel; Stohl, Andreas; Belan, Boris; Ciais, Philippe; Nédélec, Philippe

2010-05-01

In this paper we discuss the results of in-situ measurements of ultra-fine and fine aerosol particles carried out in the troposphere from 500 to 7000 m in the framework of several International and Russian State Projects. Number concentrations of ultra-fine and fine aerosol particles measured during intensive airborne campaigns are presented. Measurements carried over a great part of Siberia were focused on particles with diameters from 3 to 21 nm to study new particle formation in the free/upper troposphere over middle and high latitudes of Asia, which is the most unexplored region of the Northern Hemisphere. Joint International airborne surveys were performed along the following routes: Novosibirsk-Salekhard-Khatanga-Chokurdakh-Pevek-Yakutsk-Mirny-Novosibirsk (YAK-AEROSIB/PLARCAT2008 Project) and Novosibirsk-Mirny-Yakutsk-Lensk-Bratsk-Novosibirsk (YAK-AEROSIB Project). The flights over Lake Baikal was conducted under Russian State contract. Concentrations of ultra-fine and fine particles were measured with automated diffusion battery (ADB, designed by ICKC SB RAS, Novosibirsk, Russia) modified for airborne applications. The airborne ADB coupled with CPC has an additional aspiration unit to compensate ambient pressure and changing flow rate. It enabled to classify nanoparticles in three size ranges: 3-6 nm, 6-21 nm, and 21-200 nm. To identify new particle formation events we used similar specific criteria as Young et al. (2007): (1) N3-6nm >10 cm-3, (2) R1=N3-6/N621 >1 and R2=N321/N21200 >0.5. So when one of the ratios R1 or R2 tends to decrease to the above limits the new particle formation is weakened. It is very important to notice that space scale where new particle formation was observed is rather large. All the events revealed in the FT occurred under clean air conditions (low CO mixing ratios). Measurements carried out in the atmospheric boundary layer over Baikal Lake did not reveal any event of new particle formation. Concentrations of ultra

Quantifying streamflow change caused by forest disturbance at a large spatial scale: A single watershed study

NASA Astrophysics Data System (ADS)

Wei, Xiaohua; Zhang, Mingfang

2010-12-01

Climatic variability and forest disturbance are commonly recognized as two major drivers influencing streamflow change in large-scale forested watersheds. The greatest challenge in evaluating quantitative hydrological effects of forest disturbance is the removal of climatic effect on hydrology. In this paper, a method was designed to quantify respective contributions of large-scale forest disturbance and climatic variability on streamflow using the Willow River watershed (2860 km2) located in the central part of British Columbia, Canada. Long-term (>50 years) data on hydrology, climate, and timber harvesting history represented by equivalent clear-cutting area (ECA) were available to discern climatic and forestry influences on streamflow by three steps. First, effective precipitation, an integrated climatic index, was generated by subtracting evapotranspiration from precipitation. Second, modified double mass curves were developed by plotting accumulated annual streamflow against annual effective precipitation, which presented a much clearer picture of the cumulative effects of forest disturbance on streamflow following removal of climatic influence. The average annual streamflow changes that were attributed to forest disturbances and climatic variability were then estimated to be +58.7 and -72.4 mm, respectively. The positive (increasing) and negative (decreasing) values in streamflow change indicated opposite change directions, which suggest an offsetting effect between forest disturbance and climatic variability in the study watershed. Finally, a multivariate Autoregressive Integrated Moving Average (ARIMA) model was generated to establish quantitative relationships between accumulated annual streamflow deviation attributed to forest disturbances and annual ECA. The model was then used to project streamflow change under various timber harvesting scenarios. The methodology can be effectively applied to any large-scale single watershed where long-term data (>50

Free-Living and Particle-Associated Bacterioplankton in Large Rivers of the Mississippi River Basin Demonstrate Biogeographic Patterns

PubMed Central

Millar, Justin J.; Payne, Jason T.; Ochs, Clifford A.

2014-01-01

The different drainage basins of large rivers such as the Mississippi River represent interesting systems in which to study patterns in freshwater microbial biogeography. Spatial variability in bacterioplankton communities in six major rivers (the Upper Mississippi, Missouri, Illinois, Ohio, Tennessee, and Arkansas) of the Mississippi River Basin was characterized using Ion Torrent 16S rRNA amplicon sequencing. When all systems were combined, particle-associated (>3 μm) bacterial assemblages were found to be different from free-living bacterioplankton in terms of overall community structure, partly because of differences in the proportional abundance of sequences affiliated with major bacterial lineages (Alphaproteobacteria, Cyanobacteria, and Planctomycetes). Both particle-associated and free-living communities ordinated by river system, a pattern that was apparent even after rare sequences or those affiliated with Cyanobacteria were removed from the analyses. Ordination of samples by river system correlated with environmental characteristics of each river, such as nutrient status and turbidity. Communities in the Upper Mississippi and the Missouri and in the Ohio and the Tennessee, pairs of rivers that join each other, contained similar taxa in terms of presence-absence data but differed in the proportional abundance of major lineages. The most common sequence types detected in particle-associated communities were picocyanobacteria in the Synechococcus/Prochlorococcus/Cyanobium (Syn/Pro) clade, while free-living communities also contained a high proportion of LD12 (SAR11/Pelagibacter)-like Alphaproteobacteria. This research shows that while different tributaries of large river systems such as the Mississippi River harbor distinct bacterioplankton communities, there is also microhabitat variation such as that between free-living and particle-associated assemblages. PMID:25217018

Human exposure to large solar particle events in space

NASA Technical Reports Server (NTRS)

Townsend, L. W.; Wilson, J. W.; Shinn, J. L.; Curtis, S. B.

1992-01-01

Whenever energetic solar protons produced by solar particle events traverse bulk matter, they undergo various nuclear and atomic collision processes which significantly alter the physical characteristics and biologically important properties of their transported radiation fields. These physical interactions and their effect on the resulting radiation field within matter are described within the context of a recently developed deterministic, coupled neutron-proton space radiation transport computer code (BRYNTRN). Using this computer code, estimates of human exposure in interplanetary space, behind nominal (2 g/sq cm) and storm shelter (20 g/sq cm) thicknesses of aluminum shielding, are made for the large solar proton event of August 1972. Included in these calculations are estimates of cumulative exposures to the skin, ocular lens, and bone marrow as a function of time during the event. Risk assessment in terms of absorbed dose and dose equivalent is discussed for these organs. Also presented are estimates of organ exposures for hypothetical, worst-case flare scenarios. The rate of dose equivalent accumulation places this situation in an interesting region of dose rate between the very low values of usual concern in terrestrial radiation environments and the high-dose-rate values prevalent in radiation therapy.

Analysis of radiation risk from alpha particle component of solar particle events

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

1994-01-01

The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

Efficient Implementation of the Invariant Imbedding T-Matrix Method and the Separation of Variables Method Applied to Large Nonspherical Inhomogeneous Particles

NASA Technical Reports Server (NTRS)

Bi, Lei; Yang, Ping; Kattawar, George W.; Mishchenko, Michael I.

2012-01-01

Three terms, ''Waterman's T-matrix method'', ''extended boundary condition method (EBCM)'', and ''null field method'', have been interchangeable in the literature to indicate a method based on surface integral equations to calculate the T-matrix. Unlike the previous method, the invariant imbedding method (IIM) calculates the T-matrix by the use of a volume integral equation. In addition, the standard separation of variables method (SOV) can be applied to compute the T-matrix of a sphere centered at the origin of the coordinate system and having a maximal radius such that the sphere remains inscribed within a nonspherical particle. This study explores the feasibility of a numerical combination of the IIM and the SOV, hereafter referred to as the IIMþSOV method, for computing the single-scattering properties of nonspherical dielectric particles, which are, in general, inhomogeneous. The IIMþSOV method is shown to be capable of solving light-scattering problems for large nonspherical particles where the standard EBCM fails to converge. The IIMþSOV method is flexible and applicable to inhomogeneous particles and aggregated nonspherical particles (overlapped circumscribed spheres) representing a challenge to the standard superposition T-matrix method. The IIMþSOV computational program, developed in this study, is validated against EBCM simulated spheroid and cylinder cases with excellent numerical agreement (up to four decimal places). In addition, solutions for cylinders with large aspect ratios, inhomogeneous particles, and two-particle systems are compared with results from discrete dipole approximation (DDA) computations, and comparisons with the improved geometric-optics method (IGOM) are found to be quite encouraging.

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.

An improved method for differentiating cell-bound from internalized particles by imaging flow cytometry.

PubMed

Smirnov, Asya; Solga, Michael D; Lannigan, Joanne; Criss, Alison K

2015-08-01

Recognition, binding, internalization, and elimination of pathogens and cell debris are important functions of professional as well as non-professional phagocytes. However, high-throughput methods for quantifying cell-associated particles and discriminating bound from internalized particles have been lacking. Here we describe a protocol for using imaging flow cytometry to quantify the attached and phagocytosed particles that are associated with a population of cells. Cells were exposed to fluorescent particles, fixed, and exposed to an antibody of a different fluorophore that recognizes the particles. The antibody is added without cell permeabilization, such that the antibody only binds extracellular particles. Cells with and without associated particles were identified by imaging flow cytometry. For each cell with associated particles, a spot count algorithm was employed to quantify the number of extracellular (double fluorescent) and intracellular (single fluorescent) particles per cell, from which the percent particle internalization was determined. The spot count algorithm was empirically validated by examining the fluorescence and phase contrast images acquired by the flow cytometer. We used this protocol to measure binding and internalization of the bacterium Neisseria gonorrhoeae by primary human neutrophils, using different bacterial variants and under different cellular conditions. The results acquired using imaging flow cytometry agreed with findings that were previously obtained using conventional immunofluorescence microscopy. This protocol provides a rapid, powerful method for measuring the association and internalization of any particle by any cell type. Copyright © 2015 Elsevier B.V. All rights reserved.

LARGE SOLAR ENERGETIC PARTICLE EVENTS ASSOCIATED WITH FILAMENT ERUPTIONS OUTSIDE ACTIVE REGIONS

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

Gopalswamy, N.; Mäkelä, P.; Akiyama, S.

2015-06-10

We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ∼ 1000 km s{sup −1}) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric typemore » II bursts were present in three events, indicating that the shocks formed beyond 2–3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ∼2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10–100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.« less

Release of Micronized Copper Particles from Pressure ...

EPA Pesticide Factsheets

Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about the exposure of humans as well as the environment to the particles. Two common pathways of exposure, leaching during contact with water and transfer during physical contact, were investigated to gage potential human and environmental risk during intended use of the product. Characterization, leaching tests, and wipe tests were conducted on two representative formulations of micronized copper PTL (micronized copper azole or MCA) to quantify the levels of copper present in the treated material and the amount of copper released during use as well as to determine the form (particle or ion) of the copper after it was released. Additionally, an ionized copper pressure treated wood (alkaline copper azole or ACA) was tested for comparison. The characterization showed that copper carbonate is the primary particle form in the MCA treated wood, but other forms are also present, particularly in the MCA-1 formulation, which contained a large amount of organically complexed copper. Microscopy showed that MCA-1 contained particles roughly half the size of MCA-2. The leaching results indicate that mostly (> ~95%) ionic copper is released from the MCA wood and that the particulate copper that was released is attached to cellulose and not free in solution. A sma

Measurements of Primary Biogenic Aerosol Particles with an Ultraviolet Aerodynamic Particle Sizer (UVAPS) During AMAZE-08

NASA Astrophysics Data System (ADS)

Wollny, A. G.; Garland, R.; Pöschl, U.

2008-12-01

Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the AMazonian Aerosol CharacteriZation Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. The presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 μm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as 'viable aerosols' or 'fluorescent bioparticles' (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. First data analyses show a pronounced peak of FBAP at diameters around 2-3 μm. In this size range the biogenic particle fraction was

Old age and underlying interstitial abnormalities are risk factors for development of ARDS after pleurodesis using limited amount of large particle size talc.

PubMed

Shinno, Yuki; Kage, Hidenori; Chino, Haruka; Inaba, Atsushi; Arakawa, Sayaka; Noguchi, Satoshi; Amano, Yosuke; Yamauchi, Yasuhiro; Tanaka, Goh; Nagase, Takahide

2018-01-01

Talc pleurodesis is commonly performed to manage refractory pleural effusion or pneumothorax. It is considered as a safe procedure as long as a limited amount of large particle size talc is used. However, acute respiratory distress syndrome (ARDS) is a rare but serious complication after talc pleurodesis. We sought to determine the risk factors for the development of ARDS after pleurodesis using a limited amount of large particle size talc. We retrospectively reviewed patients who underwent pleurodesis with talc or OK-432 at the University of Tokyo Hospital. Twenty-seven and 35 patients underwent chemical pleurodesis using large particle size talc (4 g or less) or OK-432, respectively. Four of 27 (15%) patients developed ARDS after talc pleurodesis. Patients who developed ARDS were significantly older than those who did not (median 80 vs 66 years, P = 0.02) and had a higher prevalence of underlying interstitial abnormalities on chest computed tomography (CT; 2/4 vs 1/23, P < 0.05). No patient developed ARDS after pleurodesis with OK-432. This is the first case series of ARDS after pleurodesis using a limited amount of large particle size talc. Older age and underlying interstitial abnormalities on chest CT seem to be risk factors for developing ARDS after talc pleurodesis. © 2017 Asian Pacific Society of Respirology.

Low-voltage, large-strain soft electrothermal actuators based on laser-reduced graphene oxide/Ag particle composites

NASA Astrophysics Data System (ADS)

Wang, Qian; Li, Yu-Tao; Zhang, Tian-Yu; Wang, Dan-Yang; Tian, Ye; Yan, Jun-Chao; Tian, He; Yang, Yi; Yang, Fan; Ren, Tian-Ling

2018-03-01

In this paper, low-voltage, large-strain flexible electrothermal actuators (ETAs) based on laser-reduced graphene oxide (LRGO)/Ag particle composites were fabricated in a simple and cost-efficient process. By adding Ag particles to the LRGO, the sheet resistance decreased effectively. Under a driving voltage of 28 V, the actuator obtained a bending angle of 192° within 6 s. Besides, the bending deformation could be precisely controlled by the driving voltage ranging from 10° to 192°. Finally, a gripper composed of two actuators was demonstrated to manipulate a piece of polydimethylsiloxane block. With the advantages of low-voltage, fast-response, and easy-to-manufacture, the graphene based ETAs have a promising application in soft robotics and soft machines.

Particle transport and deposition: basic physics of particle kinetics.

PubMed

Tsuda, Akira; Henry, Frank S; Butler, James P

2013-10-01

The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. The particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic. Conversely, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drugs. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this article. A large portion of this article deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: (i) the physical characteristics of particles, (ii) particle behavior in gas flow, and (iii) gas-flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The article concludes with a summary and a brief discussion of areas of future research. © 2013 American Physiological Society. Compr Physiol 3:1437-1471, 2013.

Particle transport and deposition: basic physics of particle kinetics

PubMed Central

Tsuda, Akira; Henry, Frank S.; Butler, James P.

2015-01-01

The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. Whereas the particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drug. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this chapter. A large portion of this chapter deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: 1) the physical characteristics of particles, 2) particle behavior in gas flow, and 3) gas flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The chapter concludes with a summary and a brief discussion of areas of future research. PMID:24265235

Quantifying particulate matter deposition in Niwot Ridge, Colorado: Collection of dry deposition using marble inserts and particle imaging using the FlowCAM

NASA Astrophysics Data System (ADS)

Goss, Natasha R.; Mladenov, Natalie; Seibold, Christine M.; Chowanski, Kurt; Seitz, Leslie; Wellemeyer, T. Barret; Williams, Mark W.

2013-12-01

Atmospheric wet and dry deposition are important sources of carbon for remote alpine lakes and soils. The carbon inputs from dry deposition in alpine National Atmospheric Deposition Program (NADP) collectors, including aeolian dust and biological material, are not well constrained due to difficulties in retaining particulate matter in the collectors. Here, we developed and tested a marble insert for dry deposition collection at the Niwot Ridge Long Term Ecological Research Station (NWT LTER) Soddie site (3345 m) between 24 May and 8 November 2011. We conducted laboratory tests of the insert's effect on particulate matter (PM) mass and non-purgeable organic carbon (DOC) and found that the insert did not significantly change either measurement. Thus, the insert may enable dry deposition collection of PM and DOC at NADP sites. We then developed a method for enumerating the collected wet and dry deposition with the Flow Cytometer and Microscope (FlowCAM), a dynamic-image particle analysis tool. The FlowCAM has the potential to establish morphology, which affects particle settling and retention, through particle diameter and aspect ratio. Particle images were used to track the abundance of pollen grains over time. Qualitative image examination revealed that most particles were biological in nature, such as intact algal cells and pollen. Dry deposition loading to the Soddie site as determined by FlowCAM measurements was highly variable, ranging from 100 to >230 g ha-1 d-1 in June-August 2011 and peaking in late June. No significant difference in diameter or aspect ratio was found between wet and dry deposition, suggesting fundamental similarities between those deposition types. Although FlowCAM statistics and identification of particle types proved insightful, our total-particle enumeration method had a high variance and underestimated the total number of particles when compared to imaging of relatively large volumes (60-125 mL) from a single sample. We recommend use of

Importance of Variable Density and Non-Boussinesq Effects on the Drag of Spherical Particles

NASA Astrophysics Data System (ADS)

Ganguli, Swetava; Lele, Sanjiva

2017-11-01

What are the forces that act on a particle as it moves in a fluid? How do they change in the presence of significant heat transfer from the particle, a variable density fluid or gravity? Last year, using particle-resolved simulations we quantified these effects on a single spherical particle and on particles in periodic lattices when O(10-3) particle-fluid temperature difference. Large deviations (>50%) in the absolute drag are observed as λ approaches unity. Oppenheimer, et al. (2016) [1] have proposed a theoretical formula for the drag of a heated sphere at extremely low Re. We show that when Re >O(10), inertial effects completely dominate the drag while when Re particle density variation causing a non-zero volumetric dilation rate. In the limit of λ approaching 0 (Stokes' limit), the drag modification can also be captured as a correction to Stokes' drag using a suitable scaling based on the dilation rate. Stanford University - Predictive Science Academic Alliance Program (PSSAP II).

Quantified Energy Dissipation Rates in the Terrestrial Bow Shock. 1.; Analysis Techniques and Methodology

NASA Technical Reports Server (NTRS)

Wilson, L. B., III; Sibeck, D. G.; Breneman, A.W.; Le Contel, O.; Cully, C.; Turner, D. L.; Angelopoulos, V.; Malaspina, D. M.

2014-01-01

We present a detailed outline and discussion of the analysis techniques used to compare the relevance of different energy dissipation mechanisms at collisionless shock waves. We show that the low-frequency, quasi-static fields contribute less to ohmic energy dissipation, (-j · E ) (minus current density times measured electric field), than their high-frequency counterparts. In fact, we found that high-frequency, large-amplitude (greater than 100 millivolts per meter and/or greater than 1 nanotesla) waves are ubiquitous in the transition region of collisionless shocks. We quantitatively show that their fields, through wave-particle interactions, cause enough energy dissipation to regulate the global structure of collisionless shocks. The purpose of this paper, part one of two, is to outline and describe in detail the background, analysis techniques, and theoretical motivation for our new results presented in the companion paper. The companion paper presents the results of our quantitative energy dissipation rate estimates and discusses the implications. Together, the two manuscripts present the first study quantifying the contribution that high-frequency waves provide, through wave-particle interactions, to the total energy dissipation budget of collisionless shock waves.

Particles exposure while sitting at bus stops of hot and humid Singapore

NASA Astrophysics Data System (ADS)

Velasco, Erik; Tan, Sok Huang

2016-10-01

Transport microenvironments represent hotspots of personal exposure to airborne toxics, particularly of ultrafine particles. Thus, a large exposure may be experienced during daily commuting trips. Amongst these microenvironments, bus stops are critical because of the commuters' close proximity to fresh fumes rich in particles emitted by passing, idling and accelerating buses and motor vehicles, in general. Standing at a bus stop may represent a period of disproportionately high exposure and it is, therefore, essential to know the number, chemical composition and physical characteristics of such particles for a proper public health assessment and design of mobility strategies. On this account, a set of portable and battery operated sensors were used to evaluate a number of properties of the traffic particles to which thousands of citizens are daily exposed at bus stops of Singapore. In terms of fine particles, the exposure concentration was on average 1.5-3 times higher than the mean concentration at ambient level reported by the local authorities. On average 60% of those particles corresponded to black carbon. An important presence of particle-bound polycyclic aromatics was observed. The particle number concentration and active surface area were effective metrics to quantify ultrafine particles, as expected both showed strong correlations. The number of particles at bus stops was on average 3.5 times higher than at ambient level. The most alarming issue was probably the size of the particles. Assuming spherical particles, a median of 27 nm was estimated based on the active surface area and particle number data. Particles of this size form the nucleation mode, which is related to harmful health effects.

Weighted Flow Algorithms (WFA) for stochastic particle coagulation

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

DeVille, R.E.L., E-mail: rdeville@illinois.edu; Riemer, N., E-mail: nriemer@illinois.edu; West, M., E-mail: mwest@illinois.edu

2011-09-20

Stochastic particle-resolved methods are a useful way to compute the time evolution of the multi-dimensional size distribution of atmospheric aerosol particles. An effective approach to improve the efficiency of such models is the use of weighted computational particles. Here we introduce particle weighting functions that are power laws in particle size to the recently-developed particle-resolved model PartMC-MOSAIC and present the mathematical formalism of these Weighted Flow Algorithms (WFA) for particle coagulation and growth. We apply this to an urban plume scenario that simulates a particle population undergoing emission of different particle types, dilution, coagulation and aerosol chemistry along a Lagrangianmore » trajectory. We quantify the performance of the Weighted Flow Algorithm for number and mass-based quantities of relevance for atmospheric sciences applications.« less

Weighted Flow Algorithms (WFA) for stochastic particle coagulation

NASA Astrophysics Data System (ADS)

DeVille, R. E. L.; Riemer, N.; West, M.

2011-09-01

Stochastic particle-resolved methods are a useful way to compute the time evolution of the multi-dimensional size distribution of atmospheric aerosol particles. An effective approach to improve the efficiency of such models is the use of weighted computational particles. Here we introduce particle weighting functions that are power laws in particle size to the recently-developed particle-resolved model PartMC-MOSAIC and present the mathematical formalism of these Weighted Flow Algorithms (WFA) for particle coagulation and growth. We apply this to an urban plume scenario that simulates a particle population undergoing emission of different particle types, dilution, coagulation and aerosol chemistry along a Lagrangian trajectory. We quantify the performance of the Weighted Flow Algorithm for number and mass-based quantities of relevance for atmospheric sciences applications.

How Actuated Particles Effectively Capture Biomolecular Targets

PubMed Central

2017-01-01

Because of their high surface-to-volume ratio and adaptable surface functionalization, particles are widely used in bioanalytical methods to capture molecular targets. In this article, a comprehensive study is reported of the effectiveness of protein capture by actuated magnetic particles. Association rate constants are quantified in experiments as well as in Brownian dynamics simulations for different particle actuation configurations. The data reveal how the association rate depends on the particle velocity, particle density, and particle assembly characteristics. Interestingly, single particles appear to exhibit target depletion zones near their surface, caused by the high density of capture molecules. The depletion effects are even more limiting in cases with high particle densities. The depletion effects are overcome and protein capture rates are enhanced by applying dynamic particle actuation, resulting in an increase in the association rate constants by up to 2 orders of magnitude. PMID:28192952

Microfabricated particle focusing device

DOEpatents

Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

2013-04-23

A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

Quantifying subtle but persistent peri-spine inflammation in vivo to submicron cobalt-chromium alloy particles.

PubMed

Hallab, Nadim James; Chan, Frank W; Harper, Megan L

2012-12-01

We evaluated the consequences of cobalt-chromium alloy (CoCr) wear debris challenge in the peri-spine region to determine the inflammation and toxicity associated with submicron particulates of CoCr-alloy and nickel on the peri-spine. The lumbar epidural spaces of (n = 50) New Zealand white rabbits were challenged with: 2.5 mg CoCr, 5.0 mg CoCr, 10.0 mg CoCr, a positive control (20.0 mg of nickel) and a negative control (ISOVUE-M-300). The CoCr-alloy and Ni particles had a mean diameter of 0.2 and 0.6 μm, respectively. Five rabbits per dose group were studied at 12 and 24 weeks. Local and distant tissues were analyzed histologically and quantitatively analyzed immunohistochemically (TNF-α and IL-6). Histologically, wear particles were observed in all animals. There was no evidence of toxicity or local irritation noted during macroscopic observations in any CoCr-dosed animals. However, Ni-treated control animals experienced bilateral hind leg paralysis and were euthanized at Day 2. Histopathology of the Ni particle-treated group revealed severe neuropathy. Quantitative immunohistochemistry demonstrated a CoCr-alloy dose-dependent increase in cytokines (IL-6, TNF-α, p < 0.05) at 12 and 24 weeks. Subtle peri-spine inflammation associated with CoCr-alloy implant particles was dose dependent and persistent. Neuropathy can be induced by highly reactive Ni particles. This suggests peri-spine challenge with CoCr-alloy implant debris (e.g., TDA) is consistent with past reports using titanium alloy particles, i.e., mild persistent inflammation.

Factors Affecting the Occurrence of Large Solar Energetic Particle Events

NASA Astrophysics Data System (ADS)

Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Makela, P. A.; Thakur, N.

2014-12-01

In order to understand the paucity of high-energy solar energetic particle (SEP) events in solar cycle 24, we examined all major eruptions (soft X-ray flare size ≥M5.0) on the front side of the Sun during the period from December 1, 2008 to January 31, 2014. There were 59 such eruptions that were associated with CMEs. When a flux rope was fitted to the white-light CMEs observed by SOHO and STEREO it was found that the CME sources were on the disk only for 55 eruptions. There were 16 large SEP events (proton intensity ≥10 pfu in the >10 MeV channel) detected by GOES and 4 by STEREO-B in association with these eruptions. When the CMEs were grouped according to their speeds (<1500 km/s and ≥ 1500 km/s) it was found that only three of the <1500 km/s CMEs (or 11%) were associated with large SEP events compared to 17 or (61%) of the ≥ 1500 km/s CMEs. This result confirms the importance of CME speed for SEP association. In fact there were ten other large SEP events with flare size

Precision gap particle separator

DOEpatents

Benett, William J.; Miles, Robin; Jones, II., Leslie M.; Stockton, Cheryl

2004-06-08

A system for separating particles entrained in a fluid includes a base with a first channel and a second channel. A precision gap connects the first channel and the second channel. The precision gap is of a size that allows small particles to pass from the first channel into the second channel and prevents large particles from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An port directs the fluid containing the entrained particles into the first channel. An output port directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.

Characterisation of Black Carbon (BC) mixing state and flux in Beijing using single particle measurements.

NASA Astrophysics Data System (ADS)

Joshi, Rutambhara; Liu, Dantong; Allan, James; Coe, Hugh; Flynn, Michael; Broda, Kurtis; Olfert, Jason; Irwin, Martin; Sun, Yele; Fu, Pingqing; Wang, Junfeng; Ge, Xinlei; Langford, Ben; Nemitz, Eiko; Mullinger, Neil

2017-04-01

BC is generated by the incomplete combustion of carbonaceous fuels and it is an important component of fine PM2.5. In the atmosphere BC particles have a complex structure and its mixing state has crucial impact on optical properties. Quantifying the sources and emissions of black carbon in urban environments is important and presently uncertain, particularly in megacities undergoing rapid growth and change in emissions. During the winter of 2016 (10th Nov-10th Dec) the BC was characterised as part of a large joint UK-China field experiment in Beijing. This paper focuses on understanding the mixing state of BC as well as identification and quantification of BC sources. We used a combination of a Centrifugal Particle Mass Analyser (CPMA) and a Single Particle Soot Photometer (SP2) to uniquely quantify the morphology independent mass of single refractory BC particles and their coating content. The CPMA allows us to select pre-charged aerosol particles according to their mass to charge ratio and the SP2 provides information on the mass of refractory BC through a laser-induced incandescence method. Furthermore, another SP2 was used to measure the BC flux at 100m height using the Eddy Covariance method. We have successfully gathered 4 weeks of continuous measurements which include several severe pollution events in Beijing. Here we present preliminary results, characterising the distribution of coating mass on BC particles in Beijing and linking this to the main sources of BC in the city. We will provide initial estimates of the BC flux over a several kilometre footprint. Such analysis will provide important information for the further investigation of source distribution, emission, lifetime and optical properties of BC under complex environments in Beijing.

Epithelial stem cells are formed by small-particles released from particle-producing cells

PubMed Central

Kong, Wuyi; Zhu, Xiao Ping; Han, Xiu Juan; Nuo, Mu; Wang, Hong

2017-01-01

Recent spatiotemporal report demonstrated that epidermal stem cells have equal potential to divide or differentiate, with no asymmetric cell division observed. Therefore, how epithelial stem cells maintain lifelong stem-cell support still needs to be elucidated. In mouse blood and bone marrow, we found a group of large cells stained strongly for eosin and containing coiled-tubing-like structures. Many were tightly attached to each other to form large cellular clumps. After sectioning, these large cell-clumps were composed of not cells but numerous small particles, however with few small “naked” nuclei. The small particles were about 2 to 3 μm in diameter and stained dense red for eosin, so they may be rich in proteins. Besides the clumps composed of small particles, we identified clumps formed by fusion of the small particles and clumps of newly formed nucleated cells. These observations suggest that these small particles further fused and underwent cellularization. E-cadherin was expressed in particle-fusion areas, some “naked” nuclei and the newly formed nucleated cells, which suggests that these particles can form epithelial cells via fusion and nuclear remodeling. In addition, we observed similar-particle fusion before epithelial cellularization in mouse kidney ducts after kidney ischemia, which suggests that these particles can be released in the blood and carried to the target tissues for epithelial-cell regeneration. Oct4 and E-cadherin expressed in the cytoplasmic areas in cells that were rich in protein and mainly located in the center of the cellular clumps, suggesting that these newly formed cells have become tissue-specific epithelial stem cells. Our data provide evidence that these large particle-producing cells are the origin of epithelial stem cells. The epithelial stem cells are newly formed by particle fusion. PMID:28253358

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

Quantifying Stock Return Distributions in Financial Markets.

PubMed

Botta, Federico; Moat, Helen Susannah; Stanley, H Eugene; Preis, Tobias

2015-01-01

Being able to quantify the probability of large price changes in stock markets is of crucial importance in understanding financial crises that affect the lives of people worldwide. Large changes in stock market prices can arise abruptly, within a matter of minutes, or develop across much longer time scales. Here, we analyze a dataset comprising the stocks forming the Dow Jones Industrial Average at a second by second resolution in the period from January 2008 to July 2010 in order to quantify the distribution of changes in market prices at a range of time scales. We find that the tails of the distributions of logarithmic price changes, or returns, exhibit power law decays for time scales ranging from 300 seconds to 3600 seconds. For larger time scales, we find that the distributions tails exhibit exponential decay. Our findings may inform the development of models of market behavior across varying time scales.

Atomic Bose-Hubbard Systems with Single-Particle Control

NASA Astrophysics Data System (ADS)

Preiss, Philipp Moritz

Experiments with ultracold atoms in optical lattices provide outstanding opportunities to realize exotic quantum states due to a high degree of tunability and control. In this thesis, I present experiments that extend this control from global parameters to the level of individual particles. Using a quantum gas microscope for 87Rb, we have developed a single-site addressing scheme based on digital amplitude holograms. The system self-corrects for aberrations in the imaging setup and creates arbitrary beam profiles. We are thus able to shape optical potentials on the scale of single lattice sites and control the dynamics of individual atoms. We study the role of quantum statistics and interactions in the Bose-Hubbard model on the fundamental level of two particles. Bosonic quantum statistics are apparent in the Hong-Ou-Mandel interference of massive particles, which we observe in tailored double-well potentials. These underlying statistics, in combination with tunable repulsive interactions, dominate the dynamics in single- and two-particle quantum walks. We observe highly coherent position-space Bloch oscillations, bosonic bunching in Hanbury Brown-Twiss interference and the fermionization of strongly interacting bosons. Many-body states of indistinguishable quantum particles are characterized by large-scale spatial entanglement, which is difficult to detect in itinerant systems. Here, we extend the concept of Hong-Ou-Mandel interference from individual particles to many-body states to directly quantify entanglement entropy. We perform collective measurements on two copies of a quantum state and detect entanglement entropy through many-body interference. We measure the second order Renyi entropy in small Bose-Hubbard systems and detect the buildup of spatial entanglement across the superfluid-insulator transition. Our experiments open new opportunities for the single-particle-resolved preparation and characterization of many-body quantum states.

Cross-linguistic patterns in the acquisition of quantifiers.

PubMed

Katsos, Napoleon; Cummins, Chris; Ezeizabarrena, Maria-José; Gavarró, Anna; Kuvač Kraljević, Jelena; Hrzica, Gordana; Grohmann, Kleanthes K; Skordi, Athina; Jensen de López, Kristine; Sundahl, Lone; van Hout, Angeliek; Hollebrandse, Bart; Overweg, Jessica; Faber, Myrthe; van Koert, Margreet; Smith, Nafsika; Vija, Maigi; Zupping, Sirli; Kunnari, Sari; Morisseau, Tiffany; Rusieshvili, Manana; Yatsushiro, Kazuko; Fengler, Anja; Varlokosta, Spyridoula; Konstantzou, Katerina; Farby, Shira; Guasti, Maria Teresa; Vernice, Mirta; Okabe, Reiko; Isobe, Miwa; Crosthwaite, Peter; Hong, Yoonjee; Balčiūnienė, Ingrida; Ahmad Nizar, Yanti Marina; Grech, Helen; Gatt, Daniela; Cheong, Win Nee; Asbjørnsen, Arve; Torkildsen, Janne von Koss; Haman, Ewa; Miękisz, Aneta; Gagarina, Natalia; Puzanova, Julia; Anđelković, Darinka; Savić, Maja; Jošić, Smiljana; Slančová, Daniela; Kapalková, Svetlana; Barberán, Tania; Özge, Duygu; Hassan, Saima; Chan, Cecilia Yuet Hung; Okubo, Tomoya; van der Lely, Heather; Sauerland, Uli; Noveck, Ira

2016-08-16

Learners of most languages are faced with the task of acquiring words to talk about number and quantity. Much is known about the order of acquisition of number words as well as the cognitive and perceptual systems and cultural practices that shape it. Substantially less is known about the acquisition of quantifiers. Here, we consider the extent to which systems and practices that support number word acquisition can be applied to quantifier acquisition and conclude that the two domains are largely distinct in this respect. Consequently, we hypothesize that the acquisition of quantifiers is constrained by a set of factors related to each quantifier's specific meaning. We investigate competence with the expressions for "all," "none," "some," "some…not," and "most" in 31 languages, representing 11 language types, by testing 768 5-y-old children and 536 adults. We found a cross-linguistically similar order of acquisition of quantifiers, explicable in terms of four factors relating to their meaning and use. In addition, exploratory analyses reveal that language- and learner-specific factors, such as negative concord and gender, are significant predictors of variation.

Energetic Charged Particle Component or the NO(y) Budget of the Polar Middle Atmosphere

NASA Technical Reports Server (NTRS)

Vitt, F. M.; Jackman, C. H.

1999-01-01

Analysis of nitrates measured in polar ice cap snow at a high resolution shows large variations in the nitrates. It has been shown that the nitrate signal may contain a signature of solar activity [Zeller and Dreschhoff, 19951. Reactive odd nitrogen production associated with solar particle events (SPEs) and auroral activity may be a source of some of the nitrate anomalies observed in the polar ice caps. Periods of large SPEs can lead to a production of polar atmospheric odd nitrogen in excess of the ambient sources in the polar stratosphere and mesosphere, and may leave a large nitrate signal stratified in the polar ice cap. Auroral electrons and photoelectrons produce odd nitrogen in the thermosphere, some of which may be transported to the polar (>50 degrees) mesosphere and stratosphere. Sources of odd nitrogen in the polar middle atmosphere associated with SPEs, galactic cosmic rays, and auroral electron precipitation have been quantified. The relative contributions by the energetic particles sources to the Noy budget of the polar middle atmosphere (from tropopause to 50 km, from 50 degrees to 90 degrees latitude) are compared with the nitrates observed in the polar ice sheets.

International Airport Impacts to Air Quality: Size and Related Properties of Large Increases in Ultrafine Particle Number Concentrations.

PubMed

Hudda, N; Fruin, S A

2016-04-05

We measured particle size distributions and spatial patterns of particle number (PN) and particle surface area concentrations downwind from the Los Angeles International Airport (LAX) where large increases (over local background) in PN concentrations routinely extended 18 km downwind. These elevations were mostly comprised of ultrafine particles smaller than 40 nm. For a given downwind distance, the greatest increases in PN concentrations, along with the smallest mean sizes, were detected at locations under the landing jet trajectories. The smaller size of particles in the impacted area, as compared to the ambient urban aerosol, increased calculated lung deposition fractions to 0.7-0.8 from 0.5-0.7. A diffusion charging instrument (DiSCMini), that simulates alveolar lung deposition, measured a fivefold increase in alveolar-lung deposited surface area concentrations 2-3 km downwind from the airport (over local background), decreasing steadily to a twofold increase 18 km downwind. These ratios (elevated lung-deposited surface area over background) were lower than the corresponding ratios for elevated PN concentrations, which decreased from tenfold to twofold over the same distance, but the spatial patterns of elevated concentrations were similar. It appears that PN concentration can serve as a nonlinear proxy for lung deposited surface area downwind of major airports.

Large Scale Brownian Dynamics of Confined Suspensions of Rigid Particles

NASA Astrophysics Data System (ADS)

Donev, Aleksandar; Sprinkle, Brennan; Balboa, Florencio; Patankar, Neelesh

2017-11-01

We introduce new numerical methods for simulating the dynamics of passive and active Brownian colloidal suspensions of particles of arbitrary shape sedimented near a bottom wall. The methods also apply for periodic (bulk) suspensions. Our methods scale linearly in the number of particles, and enable previously unprecedented simulations of tens to hundreds of thousands of particles. We demonstrate the accuracy and efficiency of our methods on a suspension of boomerang-shaped colloids. We also model recent experiments on active dynamics of uniform suspensions of spherical microrollers. This work was supported in part by the National Science Foundation under award DMS-1418706, and by the U.S. Department of Energy under award DE-SC0008271.

PENTACLE: Parallelized particle-particle particle-tree code for planet formation

NASA Astrophysics Data System (ADS)

Iwasawa, Masaki; Oshino, Shoichi; Fujii, Michiko S.; Hori, Yasunori

2017-10-01

We have newly developed a parallelized particle-particle particle-tree code for planet formation, PENTACLE, which is a parallelized hybrid N-body integrator executed on a CPU-based (super)computer. PENTACLE uses a fourth-order Hermite algorithm to calculate gravitational interactions between particles within a cut-off radius and a Barnes-Hut tree method for gravity from particles beyond. It also implements an open-source library designed for full automatic parallelization of particle simulations, FDPS (Framework for Developing Particle Simulator), to parallelize a Barnes-Hut tree algorithm for a memory-distributed supercomputer. These allow us to handle 1-10 million particles in a high-resolution N-body simulation on CPU clusters for collisional dynamics, including physical collisions in a planetesimal disc. In this paper, we show the performance and the accuracy of PENTACLE in terms of \\tilde{R}_cut and a time-step Δt. It turns out that the accuracy of a hybrid N-body simulation is controlled through Δ t / \\tilde{R}_cut and Δ t / \\tilde{R}_cut ˜ 0.1 is necessary to simulate accurately the accretion process of a planet for ≥106 yr. For all those interested in large-scale particle simulations, PENTACLE, customized for planet formation, will be freely available from https://github.com/PENTACLE-Team/PENTACLE under the MIT licence.

Children's interpretations of general quantifiers, specific quantifiers, and generics

PubMed Central

Gelman, Susan A.; Leslie, Sarah-Jane; Was, Alexandra M.; Koch, Christina M.

2014-01-01

Recently, several scholars have hypothesized that generics are a default mode of generalization, and thus that young children may at first treat quantifiers as if they were generic in meaning. To address this issue, the present experiment provides the first in-depth, controlled examination of the interpretation of generics compared to both general quantifiers ("all Xs", "some Xs") and specific quantifiers ("all of these Xs", "some of these Xs"). We provided children (3 and 5 years) and adults with explicit frequency information regarding properties of novel categories, to chart when "some", "all", and generics are deemed appropriate. The data reveal three main findings. First, even 3-year-olds distinguish generics from quantifiers. Second, when children make errors, they tend to be in the direction of treating quantifiers like generics. Third, children were more accurate when interpreting specific versus general quantifiers. We interpret these data as providing evidence for the position that generics are a default mode of generalization, especially when reasoning about kinds. PMID:25893205

Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at $${\\sqrt{s} = 8}$$ s = 8 TeV using the ATLAS experiment

DOE PAGES

Aad, G.

2015-09-03

Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data samplemore » corresponding to an integrated luminosity of \\(18.4\\) fb\\(^{-1}\\) of pp collisions at \\(\\sqrt{s} = 8\\) TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 \\(\\%\\) confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.« less

A new statistical model for subgrid dispersion in large eddy simulations of particle-laden flows

NASA Astrophysics Data System (ADS)

Muela, Jordi; Lehmkuhl, Oriol; Pérez-Segarra, Carles David; Oliva, Asensi

2016-09-01

Dispersed multiphase turbulent flows are present in many industrial and commercial applications like internal combustion engines, turbofans, dispersion of contaminants, steam turbines, etc. Therefore, there is a clear interest in the development of models and numerical tools capable of performing detailed and reliable simulations about these kind of flows. Large Eddy Simulations offer good accuracy and reliable results together with reasonable computational requirements, making it a really interesting method to develop numerical tools for particle-laden turbulent flows. Nonetheless, in multiphase dispersed flows additional difficulties arises in LES, since the effect of the unresolved scales of the continuous phase over the dispersed phase is lost due to the filtering procedure. In order to solve this issue a model able to reconstruct the subgrid velocity seen by the particles is required. In this work a new model for the reconstruction of the subgrid scale effects over the dispersed phase is presented and assessed. This innovative methodology is based in the reconstruction of statistics via Probability Density Functions (PDFs).

Quantifying Semantic Linguistic Maturity in Children

ERIC Educational Resources Information Center

Hansson, Kristina; Bååth, Rasmus; Löhndorf, Simone; Sahlén, Birgitta; Sikström, Sverker

2016-01-01

We propose a method to quantify "semantic linguistic maturity" (SELMA) based on a high dimensional semantic representation of words created from the co-occurrence of words in a large text corpus. The method was applied to oral narratives from 108 children aged 4;0-12;10. By comparing the SELMA measure with maturity ratings made by human…

A parallel electrostatic Particle-in-Cell method on unstructured tetrahedral grids for large-scale bounded collisionless plasma simulations

NASA Astrophysics Data System (ADS)

Averkin, Sergey N.; Gatsonis, Nikolaos A.

2018-06-01

An unstructured electrostatic Particle-In-Cell (EUPIC) method is developed on arbitrary tetrahedral grids for simulation of plasmas bounded by arbitrary geometries. The electric potential in EUPIC is obtained on cell vertices from a finite volume Multi-Point Flux Approximation of Gauss' law using the indirect dual cell with Dirichlet, Neumann and external circuit boundary conditions. The resulting matrix equation for the nodal potential is solved with a restarted generalized minimal residual method (GMRES) and an ILU(0) preconditioner algorithm, parallelized using a combination of node coloring and level scheduling approaches. The electric field on vertices is obtained using the gradient theorem applied to the indirect dual cell. The algorithms for injection, particle loading, particle motion, and particle tracking are parallelized for unstructured tetrahedral grids. The algorithms for the potential solver, electric field evaluation, loading, scatter-gather algorithms are verified using analytic solutions for test cases subject to Laplace and Poisson equations. Grid sensitivity analysis examines the L2 and L∞ norms of the relative error in potential, field, and charge density as a function of edge-averaged and volume-averaged cell size. Analysis shows second order of convergence for the potential and first order of convergence for the electric field and charge density. Temporal sensitivity analysis is performed and the momentum and energy conservation properties of the particle integrators in EUPIC are examined. The effects of cell size and timestep on heating, slowing-down and the deflection times are quantified. The heating, slowing-down and the deflection times are found to be almost linearly dependent on number of particles per cell. EUPIC simulations of current collection by cylindrical Langmuir probes in collisionless plasmas show good comparison with previous experimentally validated numerical results. These simulations were also used in a parallelization

Mass-specific scattering coefficient for natural minerogenic particle populations: particle size distribution effect and closure analyses.

PubMed

Peng, Feng; Effler, Steve W

2012-05-01

The relationship between the particulate scattering coefficient (b(p)) and the concentration of suspended particulate matter (SPM), as represented by the mass-specific scattering coefficient of particulates (b(p)*=b(p)/SPM), depends on particle size distribution (PSD). This dependence is quantified for minerogenic particle populations in this paper through calculations of b(p)* for common minerals as idealized populations (monodispersed spheres); contemporaneous measurements of b(p), SPM, and light-scattering attributes of mineral particles with scanning electron microscopy interfaced with automated image and x-ray analyses (SAX), for a connected stream-reservoir system where minerogenic particles dominate b(p); and estimates of b(p) and its size dependency (through SAX results-driven Mie theory calculations), particle volume concentration, and b(p)*. Modest changes in minerogenic PSDs are shown to result in substantial variations in b(p)*. Good closure of the SAX-based estimates of b(p) and particle volume concentration with bulk measurements is demonstrated. Converging relationships between b(p)* and particle size, developed from three approaches, were well described by power law expressions.

Quantifying Stock Return Distributions in Financial Markets

PubMed Central

Botta, Federico; Moat, Helen Susannah; Stanley, H. Eugene; Preis, Tobias

2015-01-01

Being able to quantify the probability of large price changes in stock markets is of crucial importance in understanding financial crises that affect the lives of people worldwide. Large changes in stock market prices can arise abruptly, within a matter of minutes, or develop across much longer time scales. Here, we analyze a dataset comprising the stocks forming the Dow Jones Industrial Average at a second by second resolution in the period from January 2008 to July 2010 in order to quantify the distribution of changes in market prices at a range of time scales. We find that the tails of the distributions of logarithmic price changes, or returns, exhibit power law decays for time scales ranging from 300 seconds to 3600 seconds. For larger time scales, we find that the distributions tails exhibit exponential decay. Our findings may inform the development of models of market behavior across varying time scales. PMID:26327593

Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA

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

Antipov, S. A.; Nagaitsev, S.; Valishev, A.

2017-04-01

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually lead to amore » resonant behavior and a reduction of the dynamic aperture. One of the goals of the IOTA research program is to achieve a high betatron tune spread, while retaining a large dynamic aperture using conventional octupole magnets in a special but realistic accelerator configuration. In this report, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for suppression of space-charge induced instabilities in high intensity machines.« less

Surface passivity largely governs the bioaccessibility of nickel-based powder particles at human exposure conditions.

PubMed

Hedberg, Yolanda S; Herting, Gunilla; Latvala, Siiri; Elihn, Karine; Karlsson, Hanna L; Odnevall Wallinder, Inger

2016-11-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, are identified and proven safe for humans and the environment. Therefore, differences in bioaccessibility in terms of released metals in synthetic biological fluids (different pH (1.5-7.4) and composition) that are relevant for different human exposure routes (inhalation, ingestion, and dermal contact) have been assessed for powder particles of an alloy containing high levels of nickel (Inconel 718, 57 wt% nickel). This powder is compared with the bioaccessibility of two nickel-containing stainless steel powders (AISI 316L, 10-12% nickel) and with powders representing their main pure alloy constituents: two nickel metal powders (100% nickel), two iron metal powders and two chromium metal powders. X-ray photoelectron spectroscopy, microscopy, light scattering, and nitrogen absorption were employed for the particle and surface oxide characterization. Atomic absorption spectroscopy was used to quantify released amounts of metals in solution. Cytotoxicity (Alamar blue assay) and DNA damage (comet assay) of the Inconel powder were assessed following exposure of the human lung cell line A549, as well as its ability to generate reactive oxygen species (DCFH-DA assay). Despite its high nickel content, the Inconel alloy powder did not release any significant amounts of metals and did not induce any toxic response. It is concluded, that this is related to the high surface passivity of the Inconel powder governed by its chromium-rich surface oxide. Read-across from the pure metal constituents is hence not recommended either for this or any other passive alloy. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

The Effect of Particle Properties on Hot Particle Spot Fire Ignition

NASA Astrophysics Data System (ADS)

Zak, Casey David

The ignition of natural combustible material by hot metal particles is an important fire ignition pathway by which wildland and wildland-urban-interface spot fires are started. There are numerous cases reported of wild fires started by clashing power-lines or from sparks generated by machines or engines. Similarly there are many cases reported of fires caused by grinding, welding and cutting sparks. Up to this point, research on hot particle spot fire ignition has largely focused on particle generation and transport. A small number of studies have examined what occurs after a hot particle contacts a natural fuel bed, but until recently the process remained poorly understood. This work describes an investigation of the effect of particle size, temperature and thermal properties on the ability of hot particles to cause flaming ignition of cellulosic fuel beds. Both experimental and theoretical approaches are used, with a focus on understanding the physics underlying the ignition process. For the experimental study, spheres of stainless steel, aluminum, brass and copper are heated in a tube furnace and dropped onto a powdered cellulose fuel bed; the occurrence of flaming ignition or lack thereof is visually observed and recorded. This procedure is repeated a large number of times for each metal type, varying particle diameter from 2 to 11 mm and particle temperature between 575 and 1100°C. The results of these experiments are statistically analyzed to find approximate ignition boundaries and identify boundary trends with respect to the particle parameters of interest. Schlieren images recorded during the ignition experiments are also used to more accurately describe the ignition process. Based on these images, a simple theoretical model of hot particle spot fire ignition is developed and used to explore the experimental trends further. The model under-predicts the minimum ignition temperatures required for small spheres, but agrees qualitatively with the experimental

Quantitative single-particle digital autoradiography with α-particle emitters for targeted radionuclide therapy using the iQID camera.

PubMed

Miller, Brian W; Frost, Sofia H L; Frayo, Shani L; Kenoyer, Aimee L; Santos, Erlinda; Jones, Jon C; Green, Damian J; Hamlin, Donald K; Wilbur, D Scott; Fisher, Darrell R; Orozco, Johnnie J; Press, Oliver W; Pagel, John M; Sandmaier, Brenda M

2015-07-01

Alpha-emitting radionuclides exhibit a potential advantage for cancer treatments because they release large amounts of ionizing energy over a few cell diameters (50-80 μm), causing localized, irreparable double-strand DNA breaks that lead to cell death. Radioimmunotherapy (RIT) approaches using monoclonal antibodies labeled with α emitters may thus inactivate targeted cells with minimal radiation damage to surrounding tissues. Tools are needed to visualize and quantify the radioactivity distribution and absorbed doses to targeted and nontargeted cells for accurate dosimetry of all treatment regimens utilizing α particles, including RIT and others (e.g., Ra-223), especially for organs and tumors with heterogeneous radionuclide distributions. The aim of this study was to evaluate and characterize a novel single-particle digital autoradiography imager, the ionizing-radiation quantum imaging detector (iQID) camera, for use in α-RIT experiments. The iQID camera is a scintillator-based radiation detection system that images and identifies charged-particle and gamma-ray/x-ray emissions spatially and temporally on an event-by-event basis. It employs CCD-CMOS cameras and high-performance computing hardware for real-time imaging and activity quantification of tissue sections, approaching cellular resolutions. In this work, the authors evaluated its characteristics for α-particle imaging, including measurements of intrinsic detector spatial resolutions and background count rates at various detector configurations and quantification of activity distributions. The technique was assessed for quantitative imaging of astatine-211 ((211)At) activity distributions in cryosections of murine and canine tissue samples. The highest spatial resolution was measured at ∼20 μm full width at half maximum and the α-particle background was measured at a rate as low as (2.6 ± 0.5) × 10(-4) cpm/cm(2) (40 mm diameter detector area). Simultaneous imaging of multiple tissue sections was

Surgical smoke and ultrafine particles

PubMed Central

Brüske-Hohlfeld, Irene; Preissler, Gerhard; Jauch, Karl-Walter; Pitz, Mike; Nowak, Dennis; Peters, Annette; Wichmann, H-Erich

2008-01-01

Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 μm). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure. PMID:19055750

Impact of particle emissions of new laser printers on modeled office room

NASA Astrophysics Data System (ADS)

Koivisto, Antti J.; Hussein, Tareq; Niemelä, Raimo; Tuomi, Timo; Hämeri, Kaarle

2010-06-01

In this study, we present how an indoor aerosol model can be used to characterize particle emitter and predict influence of the source on indoor air quality. Particle size-resolved emission rates were quantified and the source's influence on indoor air quality was estimated by using office model simulations. We measured particle emissions from three modern laser printers in a flow-through chamber. Measured parameters were used as input parameters for an indoor aerosol model, which we then used to quantify the particle emission rates. The same indoor aerosol model was used to simulate the effect of the particle emission source inside an office model. The office model consists of a mechanically ventilated empty room and the particle source. The aerosol from the ventilation air was a filtered urban background aerosol. The effect of the ventilation rate was studied using three different ventilation ratios 1, 2 and 3 h -1. According to the model, peak emission rates of the printers exceeded 7.0 × 10 8 s -1 (2.5 × 10 12 h -1), and emitted mainly ultrafine particles (diameter less than 100 nm). The office model simulation results indicate that a print job increases ultrafine particle concentration to a maximum of 2.6 × 10 5 cm -3. Printer-emitted particles increased 6-h averaged particle concentration over eleven times compared to the background particle concentration.

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE PAGES

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

2017-05-26

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

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

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Outdoor and indoor particle characterization from a large and uncontrolled combustion of a tire landfill.

PubMed

Artíñano, B; Gómez-Moreno, F J; Díaz, E; Amato, F; Pandolfi, M; Alonso-Blanco, E; Coz, E; García-Alonso, S; Becerril-Valle, M; Querol, X; Alastuey, A; van Drooge, B L

2017-09-01

A large and uncontrolled fire of a tire landfill started in Seseña (Toledo, Spain) on May 13, 2016. An experimental deployment was immediately launched in the area for measuring regulated and non-standard air quality parameters to assess the potential impact of the plume at local and regional levels. Outdoor and indoor measurements of different parameters were carried out at a near school, approximately 700m downwind the burning tires. Real time measurements of ambient black carbon (BC) and total number particle concentrations were identified as good tracers of the smoke plume. Simultaneous peaks allowed us to characterize situations of the plume impact on the site. Outdoor total particle number concentrations reached in these occasions 3.8×10 5 particlescm -3 (on a 10min resolution) whereas the indoor concentration was one order of magnitude lower. BC mass concentrations in ambient air were in the range of 2 to 7μgm -3 , whereas concentrations<2μgm -3 were measured indoor. Indoor and outdoor deposited inhalable dust was sampled and chemically characterized. Both indoor and outdoor dust was enriched in tire components (Zn, sulfate) and PAHs associated to the tire combustion process. Infiltration processes have been documented for BC and particle number concentrations causing increases in indoor concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Explosive particle soil surface dispersion model for detonated military munitions.

PubMed

Hathaway, John E; Rishel, Jeremy P; Walsh, Marianne E; Walsh, Michael R; Taylor, Susan

2015-07-01

The accumulation of high explosive mass residue from the detonation of military munitions on training ranges is of environmental concern because of its potential to contaminate the soil, surface water, and groundwater. The US Department of Defense wants to quantify, understand, and remediate high explosive mass residue loadings that might be observed on active firing ranges. Previously, efforts using various sampling methods and techniques have resulted in limited success, due in part to the complicated dispersion pattern of the explosive particle residues upon detonation. In our efforts to simulate particle dispersal for high- and low-order explosions on hypothetical firing ranges, we use experimental particle data from detonations of munitions from a 155-mm howitzer, which are common military munitions. The mass loadings resulting from these simulations provide a previously unattained level of detail to quantify the explosive residue source-term for use in soil and water transport models. In addition, the resulting particle placements can be used to test, validate, and optimize particle sampling methods and statistical models as applied to firing ranges. Although the presented results are for a hypothetical 155-mm howitzer firing range, the method can be used for other munition types once the explosive particle characteristics are known.

The oncogenic transforming potential of the passage of single α particles through mammalian cell nuclei

PubMed Central

Miller, Richard C.; Randers-Pehrson, Gerhard; Geard, Charles R.; Hall, Eric J.; Brenner, David J.

1999-01-01

Domestic, low-level exposure to radon gas is considered a major environmental lung-cancer hazard involving DNA damage to bronchial cells by α particles from radon progeny. At domestic exposure levels, the relevant bronchial cells are very rarely traversed by more than one α particle, whereas at higher radon levels—at which epidemiological studies in uranium miners allow lung-cancer risks to be quantified with reasonable precision—these bronchial cells are frequently exposed to multiple α-particle traversals. Measuring the oncogenic transforming effects of exactly one α particle without the confounding effects of multiple traversals has hitherto been unfeasible, resulting in uncertainty in extrapolations of risk from high to domestic radon levels. A technique to assess the effects of single α particles uses a charged-particle microbeam, which irradiates individual cells or cell nuclei with predefined exact numbers of particles. Although previously too slow to assess the relevant small oncogenic risks, recent improvements in throughput now permit microbeam irradiation of large cell numbers, allowing the first oncogenic risk measurements for the traversal of exactly one α particle through a cell nucleus. Given positive controls to ensure that the dosimetry and biological controls were comparable, the measured oncogenicity from exactly one α particle was significantly lower than for a Poisson-distributed mean of one α particle, implying that cells traversed by multiple α particles contribute most of the risk. If this result applies generally, extrapolation from high-level radon risks (involving cellular traversal by multiple α particles) may overestimate low-level (involving only single α particles) radon risks. PMID:9874764

Effect of Particle Shape on Mechanical Behaviors of Rocks: A Numerical Study Using Clumped Particle Model

PubMed Central

Rong, Guan; Liu, Guang; Zhou, Chuang-bing

2013-01-01

Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied. PMID:23997677

Effect of particle shape on mechanical behaviors of rocks: a numerical study using clumped particle model.

PubMed

Rong, Guan; Liu, Guang; Hou, Di; Zhou, Chuang-Bing

2013-01-01

Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied.

Asymptotic Solutions for Optical Properties of Large Particles with Strong Absorption

NASA Technical Reports Server (NTRS)

Yang, Ping; Gao, Bo-Cai; Baum, Bryan A.; Hu, Yong X.; Wiscombe, Warren J.; Mishchenko, Michael I.; Winker, Dave M.; Nasiri, Shaima L.; Einaudi, Franco (Technical Monitor)

2000-01-01

For scattering calculations involving nonspherical particles such as ice crystals, we show that the transverse wave condition is not applicable to the refracted electromagnetic wave in the context of geometric optics when absorption is involved. Either the TM wave condition (i.e., where the magnetic field of the refracted wave is transverse with respect to the wave direction) or the TE wave condition (i.e., where the electric field is transverse with respect to the propagating direction of the wave) may be assumed for the refracted wave in an absorbing medium to locally satisfy the electromagnetic boundary condition in the ray tracing calculation. The wave mode assumed for the refracted wave affects both the reflection and refraction coefficients. As a result, a nonunique solution for these coefficients is derived from the electromagnetic boundary condition. In this study we have identified the appropriate solution for the Fresnel reflection/refraction coefficients in light scattering calculation based on the ray tracing technique. We present the 3 x 2 refraction or transmission matrix that completely accounts for the inhomogeneity of the refracted wave in an absorbing medium. Using the Fresnel coefficients for an absorbing medium, we derive an asymptotic solution in an analytical format for the scattering properties of a general polyhedral particle. Numerical results are presented for hexagonal plates and columns with both preferred and random orientations. The asymptotic theory can produce reasonable accuracy in the phase function calculations in the infrared window region (wavelengths near 10 micron) if the particle size (in diameter) is on the order of 40 micron or larger. However, since strong absorption is assumed in the computation of the single-scattering albedo in the asymptotic theory, the single scattering albedo does not change with variation of the particle size. As a result, the asymptotic theory can lead to substantial errors in the computation of

Particle size distribution of brown and white rice during gastric digestion measured by image analysis.

PubMed

Bornhorst, Gail M; Kostlan, Kevin; Singh, R Paul

2013-09-01

The particle size distribution of foods during gastric digestion indicates the amount of physical breakdown that occurred due to the peristaltic movement of the stomach walls in addition to the breakdown that initially occurred during oral processing. The objective of this study was to present an image analysis technique that was rapid, simple, and could distinguish between food components (that is, rice kernel and bran layer in brown rice). The technique was used to quantify particle breakdown of brown and white rice during gastric digestion in growing pigs (used as a model for an adult human) over 480 min of digestion. The particle area distributions were fit to a Rosin-Rammler distribution function. Brown and white rice exhibited considerable breakdown as the number of particles per image decreased over time. The median particle area (x(50)) increased during digestion, suggesting a gastric sieving phenomenon, where small particles were emptied and larger particles were retained for additional breakdown. Brown rice breakdown was further quantified by an examination of the bran layer fragments and rice grain pieces. The percentage of total particle area composed of bran layer fragments was greater in the distal stomach than the proximal stomach in the first 120 min of digestion. The results of this study showed that image analysis may be used to quantify particle breakdown of a soft food product during gastric digestion, discriminate between different food components, and help to clarify the role of food structure and processing in food breakdown during gastric digestion. © 2013 Institute of Food Technologists®

Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

DOE PAGES

Berenji, B.; Gaskins, J.; Meyer, M.

2016-02-16

We present constraints on the nature of axions and axion–like particles (ALPs) by analyzing gamma–ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon–nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma–ray spectrum arising from subsequent axion decays. By analyzing 5 years of gamma-ray data (between 60 MeV and 200 MeV) for a sample of 4 nearby neutron stars, we do not find evidence for anmore » axion or ALP signal, thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9×10 -2 eV, which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6×10 7 GeV. Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.« less

Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

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

Berenji, B.; Gaskins, J.; Meyer, M.

We present constraints on the nature of axions and axion–like particles (ALPs) by analyzing gamma–ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong CP problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon–nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma–ray spectrum arising from subsequent axion decays. By analyzing 5 years of gamma-ray data (between 60 MeV and 200 MeV) for a sample of 4 nearby neutron stars, we do not find evidence for anmore » axion or ALP signal, thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9×10 -2 eV, which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6×10 7 GeV. Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.« less

Impact of particle concentration and out-of-range sizes on the measurements of the LISST

NASA Astrophysics Data System (ADS)

Zhao, Lin; Boufadel, Michel C.; King, Thomas; Robinson, Brian; Conmy, Robyn; Lee, Kenneth

2018-05-01

The instrument LISST (laser in situ scattering and transmissiometry) has been widely used for measuring the size of oil droplets in relation to oil spills and sediment particles. Major concerns associated with using the instrument include the impact of high concentrations and/or out-of-range particle (droplet) sizes on the LISST reading. These were evaluated experimentally in this study using monosized microsphere particles. The key findings include: (1) When high particle concentration reduced the optical transmission (OT) to below 30%, the measured peak value tended to underestimate the true peak value, and the accuracy of the LISST decreased by ~8% to ~28%. The maximum concentration to reach the 30% OT was about 50% of the theoretical values, suggesting a lower concentration level should be considered during the instrument deployment. (2) The out-of-range sizes of particles affected the LISST measurements when the sizes were close to the LISST measurement range. Fine below-range sizes primarily affected the data in the lowest two bins of the LISST with  >75% of the volume at the smallest bin. Large out-of-range particles affected the sizes of the largest 8–10 bins only when very high concentration was present. The out-of-range particles slightly changed the size distribution of the in-range particles, but their concentration was conserved. An approach to interpret and quantify the effects of the out-of-range particles on the LISST measurement was proposed.

Ice nucleating particles from a large-scale sampling network: insight into geographic and temporal variability

NASA Astrophysics Data System (ADS)

Schrod, Jann; Weber, Daniel; Thomson, Erik S.; Pöhlker, Christopher; Saturno, Jorge; Artaxo, Paulo; Curtius, Joachim; Bingemer, Heinz

2017-04-01

The number concentration of ice nucleating particles (INP) is an important, yet under quantified atmospheric parameter. The temporal and geographic extent of observations worldwide remains relatively small, with many regions of the world (even whole continents and oceans), almost completely unrepresented by observational data. Measurements at pristine sites are particularly rare, but all the more valuable because such observations are necessary to estimate the pre-industrial baseline of aerosol and cloud related parameters that are needed to better understand the climate system and forecast future scenarios. As a partner of BACCHUS we began in September 2014 to operate an INP measurement network of four sampling stations, with a global geographic distribution. The stations are located at unique sites reaching from the Arctic to the equator: the Amazonian Tall Tower Observatory ATTO in Brazil, the Observatoire Volcanologique et Sismologique on the island of Martinique in the Caribbean Sea, the Zeppelin Observatory at Svalbard in the Norwegian Arctic and the Taunus Observatory near Frankfurt, Germany. Since 2014 samples were collected regularly by electrostatic precipitation of aerosol particles onto silicon substrates. The INP on the substrate are activated and analyzed in the isothermal static diffusion chamber FRIDGE at temperatures between -20°C and -30°C and relative humidity with respect to ice from 115 to 135%. Here we present data from the years 2015 and 2016 from this novel INP network and from selected campaign-based measurements from remote sites, including the Mt. Kenya GAW station. Acknowledgements The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) project BACCHUS under grant agreement No 603445 and the Deutsche Forschungsgemeinschaft (DFG) under the Research Unit FOR 1525 (INUIT).

Quantifying Transmission Heterogeneity Using Both Pathogen Phylogenies and Incidence Time Series

PubMed Central

Li, Lucy M.; Grassly, Nicholas C.; Fraser, Christophe

2017-01-01

Abstract Heterogeneity in individual-level transmissibility can be quantified by the dispersion parameter k of the offspring distribution. Quantifying heterogeneity is important as it affects other parameter estimates, it modulates the degree of unpredictability of an epidemic, and it needs to be accounted for in models of infection control. Aggregated data such as incidence time series are often not sufficiently informative to estimate k. Incorporating phylogenetic analysis can help to estimate k concurrently with other epidemiological parameters. We have developed an inference framework that uses particle Markov Chain Monte Carlo to estimate k and other epidemiological parameters using both incidence time series and the pathogen phylogeny. Using the framework to fit a modified compartmental transmission model that includes the parameter k to simulated data, we found that more accurate and less biased estimates of the reproductive number were obtained by combining epidemiological and phylogenetic analyses. However, k was most accurately estimated using pathogen phylogeny alone. Accurately estimating k was necessary for unbiased estimates of the reproductive number, but it did not affect the accuracy of reporting probability and epidemic start date estimates. We further demonstrated that inference was possible in the presence of phylogenetic uncertainty by sampling from the posterior distribution of phylogenies. Finally, we used the inference framework to estimate transmission parameters from epidemiological and genetic data collected during a poliovirus outbreak. Despite the large degree of phylogenetic uncertainty, we demonstrated that incorporating phylogenetic data in parameter inference improved the accuracy and precision of estimates. PMID:28981709

CFD Modelling of Particle Mixtures in a 2D CFB

NASA Astrophysics Data System (ADS)

Seppälä, M.; Kallio, S.

The capability of Fluent 6.2.16 to simulate particle mixtures in a laboratory scale 2D circulating fluidized bed (CFB) unit has been tested. In the simulations, the solids were described as one or two particle phases. The loading ratio of small to large particles, particle diameters and the gas inflow velocity were varied. The 40 cm wide and 3 m high 2D CFB was modeled using a grid with 31080 cells. The outflow of particles at the top of the CFB was monitored and emanated particles were fed back to the riser through a return duct. The paper presents the segregation patterns of the particle phases obtained from the simulations. When the fraction of large particles was 50% or larger, large particles segregated, as expected, to the wall regions and to the bottom part of the riser. However, when the fraction of large particles was 10%, an excess of large particles was found in the upper half of the riser. The explanation for this unexpected phenomenon was found in the distribution of the large particles between the slow clusters and the faster moving lean suspension.

Isocratic and gradient impedance plot analysis and comparison of some recently introduced large size core-shell and fully porous particles.

PubMed

Vanderheyden, Yoachim; Cabooter, Deirdre; Desmet, Gert; Broeckhoven, Ken

2013-10-18

The intrinsic kinetic performance of three recently commercialized large size (≥4μm) core-shell particles packed in columns with different lengths has been measured and compared with that of standard fully porous particles of similar and smaller size (5 and 3.5μm, respectively). The kinetic performance is compared in both absolute (plot of t0 versus the plate count N or the peak capacity np for isocratic and gradient elution, respectively) and dimensionless units. The latter is realized by switching to so-called impedance plots, a format which has been previously introduced (as a plot of t0/N(2) or E0 versus Nopt/N) and has in the present study been extended from isocratic to gradient elution (where the impedance plot corresponds to a plot of t0/np(4) versus np,opt(2)/np(2)). Both the isocratic and gradient impedance plot yielded a very similar picture: the clustered impedance plot curves divide into two distinct groups, one for the core-shell particles (lowest values, i.e. best performance) and one for the fully porous particles (highest values), confirming the clear intrinsic kinetic advantage of core-shell particles. If used around their optimal flow rate, the core-shell particles displayed a minimal separation impedance that is about 40% lower than the fully porous particles. Even larger gains in separation speed can be achieved in the C-term regime. Copyright © 2013 Elsevier B.V. All rights reserved.

Collisions of droplets on spherical particles

NASA Astrophysics Data System (ADS)

Charalampous, Georgios; Hardalupas, Yannis

2017-10-01

Head-on collisions between droplets and spherical particles are examined for water droplets in the diameter range between 170 μm and 280 μm and spherical particles in the diameter range between 500 μm and 2000 μm. The droplet velocities range between 6 m/s and 11 m/s, while the spherical particles are fixed in space. The Weber and Ohnesorge numbers and ratio of droplet to particle diameter were between 92 < We < 1015, 0.0070 < Oh < 0.0089, and 0.09 < Ω < 0.55, respectively. The droplet-particle collisions are first quantified in terms of the outcome. In addition to the conventional deposition and splashing regimes, a regime is observed in the intermediate region, where the droplet forms a stable crown, which does not breakup but propagates along the particle surface and passes around the particle. This regime is prevalent when the droplets collide on small particles. The characteristics of the collision at the onset of rim instability are also described in terms of the location of the film on the particle surface and the orientation and length of the ejected crown. Proper orthogonal decomposition identified that the first 2 modes are enough to capture the overall morphology of the crown at the splashing threshold.

Quantifying the contribution of ambient and indoor-generated fine particles to indoor air in residential environments.

PubMed

MacNeill, M; Kearney, J; Wallace, L; Gibson, M; Héroux, M E; Kuchta, J; Guernsey, J R; Wheeler, A J

2014-08-01

Indoor fine particles (FPs) are a combination of ambient particles that have infiltrated indoors, and particles that have been generated indoors from activities such as cooking. The objective of this paper was to estimate the infiltration factor (Finf ) and the ambient/non-ambient components of indoor FPs. To do this, continuous measurements were collected indoors and outdoors for seven consecutive days in 50 non-smoking homes in Halifax, Nova Scotia in both summer and winter using DustTrak (TSI Inc) photometers. Additionally, indoor and outdoor gravimetric measurements were made for each 24-h period in each home, using Harvard impactors (HI). A computerized algorithm was developed to remove (censor) peaks due to indoor sources. The censored indoor/outdoor ratio was then used to estimate daily Finfs and to determine the ambient and non-ambient components of total indoor concentrations. Finf estimates in Halifax (daily summer median = 0.80; daily winter median = 0.55) were higher than have been reported in other parts of Canada. In both winter and summer, the majority of FP was of ambient origin (daily winter median = 59%; daily summer median = 84%). Predictors of the non-ambient component included various cooking variables, combustion sources, relative humidity, and factors influencing ventilation. This work highlights the fact that regional factors can influence the contribution of ambient particles to indoor residential concentrations. Ambient and non-ambient particles have different risk management approaches, composition, and likely toxicity. Therefore, a better understanding of their contribution to the indoor environment is important to manage the health risks associated with fine particles (FPs) effectively. As well, a better understanding of the factors Finf can help improve exposure assessment and contribute to reduced exposure misclassification in epidemiologic studies. © 2013 Her Majesty the Queen in Right of Canada Indoor Air © 2013 John Wiley & Sons

Photonic Low Cost Micro-Sensor for in-Line Wear Particle Detection in Flowing Lube Oils.

PubMed

Mabe, Jon; Zubia, Joseba; Gorritxategi, Eneko

2017-03-14

The presence of microscopic particles in suspension in industrial fluids is often an early warning of latent or imminent failures in the equipment or processes where they are being used. This manuscript describes work undertaken to integrate different photonic principles with a micro- mechanical fluidic structure and an embedded processor to develop a fully autonomous wear debris sensor for in-line monitoring of industrial fluids. Lens-less microscopy, stroboscopic illumination, a CMOS imager and embedded machine vision technologies have been merged to develop a sensor solution that is able to detect and quantify the number and size of micrometric particles suspended in a continuous flow of a fluid. A laboratory test-bench has been arranged for setting up the configuration of the optical components targeting a static oil sample and then a sensor prototype has been developed for migrating the measurement principles to real conditions in terms of operating pressure and flow rate of the oil. Imaging performance is quantified using micro calibrated samples, as well as by measuring real used lubricated oils. Sampling a large fluid volume with a decent 2D spatial resolution, this photonic micro sensor offers a powerful tool at very low cost and compacted size for in-line wear debris monitoring.

Photonic Low Cost Micro-Sensor for in-Line Wear Particle Detection in Flowing Lube Oils

PubMed Central

Mabe, Jon; Zubia, Joseba; Gorritxategi, Eneko

2017-01-01

The presence of microscopic particles in suspension in industrial fluids is often an early warning of latent or imminent failures in the equipment or processes where they are being used. This manuscript describes work undertaken to integrate different photonic principles with a micro- mechanical fluidic structure and an embedded processor to develop a fully autonomous wear debris sensor for in-line monitoring of industrial fluids. Lens-less microscopy, stroboscopic illumination, a CMOS imager and embedded machine vision technologies have been merged to develop a sensor solution that is able to detect and quantify the number and size of micrometric particles suspended in a continuous flow of a fluid. A laboratory test-bench has been arranged for setting up the configuration of the optical components targeting a static oil sample and then a sensor prototype has been developed for migrating the measurement principles to real conditions in terms of operating pressure and flow rate of the oil. Imaging performance is quantified using micro calibrated samples, as well as by measuring real used lubricated oils. Sampling a large fluid volume with a decent 2D spatial resolution, this photonic micro sensor offers a powerful tool at very low cost and compacted size for in-line wear debris monitoring. PMID:28335436

Shannon entropy and particle decays

NASA Astrophysics Data System (ADS)

Carrasco Millán, Pedro; García-Ferrero, M. Ángeles; Llanes-Estrada, Felipe J.; Porras Riojano, Ana; Sánchez García, Esteban M.

2018-05-01

We deploy Shannon's information entropy to the distribution of branching fractions in a particle decay. This serves to quantify how important a given new reported decay channel is, from the point of view of the information that it adds to the already known ones. Because the entropy is additive, one can subdivide the set of channels and discuss, for example, how much information the discovery of a new decay branching would add; or subdivide the decay distribution down to the level of individual quantum states (which can be quickly counted by the phase space). We illustrate the concept with some examples of experimentally known particle decay distributions.

Further Discussion: Parametric Study of Wind Generated Supermicron Particle Effects in Large Fires

NASA Technical Reports Server (NTRS)

Toon, O. B.; Ackerman, T. P.

1987-01-01

In their reply (Porch et al., 1987) to our comments (Turco et al., 1987) on their smoke-scavenging-by-dust paper, Porch et al. attempt to justify a number of parameter assumptions in their original article, again revealing the extreme nature of those assumptions, particularly in the situation where all are taken simultaneously. In critiquing Porch et al.'s calculations, have not applied "opinion", but rather physical reality and common sense expressed through basic experimental results and logical physical bounds. A few examples of the unrealistic conditions required by the Porch et al. scavenging scheme, as described in their paper and comments, should suffice here. ) Porch et al. have fabricated a "fetch" region for dust particles in large fire plumes that logically must extend over an area up to 50 times greater than the fire area itself. Alternatively, they have invoked significant "necking down' of the fire plume, so that its cross-sectional area is at most a few percent of the fire area. Such severe constriction is seen only in very small fires with strong, organized vorticity, and then only over a limited plume rise region. No "fetch" has ever been noted in any large-scale fires we have observed, or for which accounts are available. Indeed, as we deduced in our original comments, complete dust scavenging even within the fire zone would probably occur less than 10% of the time for large urban fires.

Incorporation of photosenzitizer hypericin into synthetic lipid-based nano-particles for drug delivery and large unilamellar vesicles with different content of cholesterol

NASA Astrophysics Data System (ADS)

Joniova, Jaroslava; Blascakova, Ludmila; Jancura, Daniel; Nadova, Zuzana; Sureau, Franck; Miskovsky, Pavol

2014-08-01

Low-density lipoproteins (LDL) and high-density lipoproteins (HDL) are attractive natural occurring vehicles for drug delivery and targeting to cancer tissues. The capacity of both types of the lipoproteins to bind hydrophobic drugs and their functionality as drug carriers have been examined in several studies and it has been also shown that mixing of anticancer drugs with LDL or HDL before administration led to an increase of cytotoxic effects of the drugs in the comparison when the drugs were administered alone. However, a difficult isolation of the lipoproteins in large quantity from a biological organism as well as a variability of the composition and size of these molecules makes practical application of LDL and HDL as drug delivery systems quite complicated. Synthetic LDL and HDL and large unilamellar vesicles (LUV) are potentially suitable candidates to substitute the native lipoproteins for targeted and effective drug delivery. In this work, we have studied process of an association of potent photosensitizer hypericin (Hyp) with synthetic lipid-based nano-particles (sLNP) and large unilamellar vesicles (LUV) containing various amount of cholesterol. Cholesterol is one of the main components of both LDL and HDL particles and its presence in biological membranes is known to be a determining factor for membrane properties. It was found that the behavior of Hyp incorporation into sLNP particles with diameter ca ~ 90 nm is qualitatively very similar to that of Hyp incorporation into LDL (diameter ca. 22 nm) and these particles are able to enter U-87 MG cells by endocytosis. The presence of cholesterol in LUV influences the capacity of these vesicles to incorporate Hyp into their structure.

Particle Events as a Possible Source of Large Ozone Loss during Magnetic Polarity Transitions

NASA Technical Reports Server (NTRS)

vonKoenig, M.; Burrows, J. P.; Chipperfield, M. P.; Jackman, C. H.; Kallenrode, M.-B.; Kuenzi, K. F.; Quack, M.

2002-01-01

The energy deposition in the mesosphere and stratosphere during large extraterrestrial charged particle precipitation events has been known for some time to contribute to ozone losses due to the formation of potential ozone destroying species like NO(sub x), and HO(sub x). These impacts have been measured and can be reproduced with chemistry models fairly well. In the recent past, however, even the impact of the largest solar proton events on the total amount of ozone has been small compared to the dynamical variability of ozone, and to the anthropogenic induced impacts like the Antarctic 'ozone hole'. This is due to the shielding effect of the magnetic field. However, there is evidence that the earth's magnetic field may approach a reversal. This could lead to a decrease of magnetic field strength to less than 25% of its usual value over a period of several centuries . We show that with realistic estimates of very large solar proton events, scenarios similar to the Antarctic ozone hole of the 1990s may occur during a magnetic polarity transition.

Understanding and Quantifying the Reactivity of Energetic NanoParticles and NanoComposites

DTIC Science & Technology

2010-08-30

K. J.; Jung , H. J.; Kittelson, D. B.; Roberts, J. T.; Zachariah, M. R. Journal of Physical Chemistry A 2002, 106, 96. (37) Kim, S. H.; Fletcher, R...43) Kim, S. H.; Zachariah, M. R. Journal of Physical Chemistry B 2006, 110, 4555. (44) Higgins, K. J.; Jung , H. J.; Kittelson, D. B.; Roberts...Measurement of airborne particles, 2 ed.; John Wiley & Sons, Inc.: New York, NY, 1999. (46) Jung , H.; Kittelson, D. B.; Zachariah, M. R. Combustion and

First passage times in homogeneous nucleation: Dependence on the total number of particles

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

Yvinec, Romain; Bernard, Samuel; Pujo-Menjouet, Laurent

2016-01-21

Motivated by nucleation and molecular aggregation in physical, chemical, and biological settings, we present an extension to a thorough analysis of the stochastic self-assembly of a fixed number of identical particles in a finite volume. We study the statistics of times required for maximal clusters to be completed, starting from a pure-monomeric particle configuration. For finite volumes, we extend previous analytical approaches to the case of arbitrary size-dependent aggregation and fragmentation kinetic rates. For larger volumes, we develop a scaling framework to study the first assembly time behavior as a function of the total quantity of particles. We find thatmore » the mean time to first completion of a maximum-sized cluster may have a surprisingly weak dependence on the total number of particles. We highlight how higher statistics (variance, distribution) of the first passage time may nevertheless help to infer key parameters, such as the size of the maximum cluster. Finally, we present a framework to quantify formation of macroscopic sized clusters, which are (asymptotically) very unlikely and occur as a large deviation phenomenon from the mean-field limit. We argue that this framework is suitable to describe phase transition phenomena, as inherent infrequent stochastic processes, in contrast to classical nucleation theory.« less

First passage times in homogeneous nucleation: Dependence on the total number of particles

NASA Astrophysics Data System (ADS)

Yvinec, Romain; Bernard, Samuel; Hingant, Erwan; Pujo-Menjouet, Laurent

2016-01-01

Motivated by nucleation and molecular aggregation in physical, chemical, and biological settings, we present an extension to a thorough analysis of the stochastic self-assembly of a fixed number of identical particles in a finite volume. We study the statistics of times required for maximal clusters to be completed, starting from a pure-monomeric particle configuration. For finite volumes, we extend previous analytical approaches to the case of arbitrary size-dependent aggregation and fragmentation kinetic rates. For larger volumes, we develop a scaling framework to study the first assembly time behavior as a function of the total quantity of particles. We find that the mean time to first completion of a maximum-sized cluster may have a surprisingly weak dependence on the total number of particles. We highlight how higher statistics (variance, distribution) of the first passage time may nevertheless help to infer key parameters, such as the size of the maximum cluster. Finally, we present a framework to quantify formation of macroscopic sized clusters, which are (asymptotically) very unlikely and occur as a large deviation phenomenon from the mean-field limit. We argue that this framework is suitable to describe phase transition phenomena, as inherent infrequent stochastic processes, in contrast to classical nucleation theory.

Quantifying (dis)agreement between direct detection experiments in a halo-independent way

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

Feldstein, Brian; Kahlhoefer, Felix, E-mail: brian.feldstein@physics.ox.ac.uk, E-mail: felix.kahlhoefer@physics.ox.ac.uk

We propose an improved method to study recent and near-future dark matter direct detection experiments with small numbers of observed events. Our method determines in a quantitative and halo-independent way whether the experiments point towards a consistent dark matter signal and identifies the best-fit dark matter parameters. To achieve true halo independence, we apply a recently developed method based on finding the velocity distribution that best describes a given set of data. For a quantitative global analysis we construct a likelihood function suitable for small numbers of events, which allows us to determine the best-fit particle physics properties of darkmore » matter considering all experiments simultaneously. Based on this likelihood function we propose a new test statistic that quantifies how well the proposed model fits the data and how large the tension between different direct detection experiments is. We perform Monte Carlo simulations in order to determine the probability distribution function of this test statistic and to calculate the p-value for both the dark matter hypothesis and the background-only hypothesis.« less

Volcanic ash ingestion by a large gas turbine aeroengine: fan-particle interaction

NASA Astrophysics Data System (ADS)

Vogel, Andreas; Clarkson, Rory; Durant, Adam; Cassiani, Massimo; Stohl, Andreas

2016-04-01

Airborne particles from explosive volcanic eruptions are a major safety threat for aviation operations. The fine fraction of the emitted particles (<63 microns diameter) may remain in the atmosphere for days, or even weeks, and can affect commercial air traffic routes. Over the past century, there have been a considerable number of aircraft encounters with drifting volcanic ash clouds. Particles ingested into the engine cause erosion of upstream surfaces of compressor fan blades and rotor-path components, and can also cause contamination or blockage of electrical systems and the fuel system such as fuel nozzles and air bleed filters. Ash particles that enter the hot-section of the engine (combustor and turbine stages; temperature between 1400-1800°C) are rapidly heated above the glass transition temperature (about 650-1000°C) and become soft (or form a melt) and can stick as re-solidified deposits on nozzle guide vanes. The glass deposits change the internal aerodynamic airflow in the engine and can affect the cooling capability of the different components by clogging the cooling inlets/outlets, which can lead to a loss of power or flame-out. The nature of volcanic ash ingestion is primarily influenced by the fan at the front of the engine which produces the thrust that drives the aircraft. The ingested air is split between the core (compressor/combustor/turbine) and bypass (thrust) at a ratio of typically between, 1:5-10 on modern engines. Consequently, the ash particles are fractionated between the core and bypass by the geometry and dynamics of the fan blades. This study uses computational fluid dynamics (CFD) simulations of particle-laden airflows into a turbofan engine under different atmospheric and engine operation conditions. The main aim was to investigate the possible centrifugal effect of the fan blades as a function of particle size, and to relate this to the core intake concentration. We generated a generic 3D axial high-bypass turbofan engine using

Pile-Driving Pressure and Particle Velocity at the Seabed: Quantifying Effects on Crustaceans and Groundfish.

PubMed

Miller, James H; Potty, Gopu R; Kim, Hui-Kwan

2016-01-01

We modeled the effects of pile driving on crustaceans, groundfish, and other animals near the seafloor. Three different waves were investigated, including the compressional wave, shear wave, and interface wave. A finite element (FE) technique was employed in and around the pile, whereas a parabolic equation (PE) code was used to predict propagation at long ranges from the pile. Pressure, particle displacement, and particle velocity are presented as a function of range at the seafloor for a shallow-water environment near Rhode Island. We discuss the potential effects on animals near the seafloor.

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies

PubMed Central

Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-01-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies. PMID:24658586

Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies.

PubMed

Liu, Aiqin; Ingham, Eileen; Fisher, John; Tipper, Joanne L

2014-04-01

It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies.

Elucidating Particle Acidity during North China Winter Haze Events

NASA Astrophysics Data System (ADS)

Song, S.; Gao, M.; Sun, Y.; Li, M.; Wang, S.; Wang, Y.; Xu, W.; Zhu, L.; Munger, W.; McElroy, M. B.

2017-12-01

A characteristic feature of North China winter haze pollution is the rapid formation of sulfate. An accurate prediction of particle acidity, or pH, is critical for evaluating the contributions of various aqueous and heterogeneous sulfate production mechanisms (e.g. the reactions involving reactive nitrogen and transition metal ions), and is also important for evaluating the toxicity of atmospheric particles. However, particle acidity during winter haze periods is poorly constrained, and estimates in several recent studies display significant discrepancies, ranging from moderately acidic (pH 4) to neutral (pH 7). In this study, we calculate fine particle pH for several haze episodes during the 2014/2015 winter, using several methods including phase partitioning of ammonia, ion balance, and multiple thermodynamic equilibrium models. Hourly gaseous and particle composition measurements were taken at an urban site in Beijing. We find that the discrepancies in the calculated pH for recent studies are largely due to their differences in assumed methodology. The ion balance method and the reverse modes of thermodynamic models (using only aerosol phase compositions as input) are not suitable for calculating pH in this atmospheric environment. We also find, for the first time, that hydroxymethanesulfonate (HMS), formed from complexation of sulfite and bisulfite with formaldehyde in the aqueous phase, can serve as a tracer of particle pH during winter haze events. Here the concentrations of HMS are quantified using measurement data from an Aerodyne high-resolution aerosol mass spectrometer. HMS is found to contribute a few percent to particle mass during winter haze episodes. The presence of HMS is also identified with data from a single particle aerosol mass spectrometer. Since it may be incorrectly identified as sulfate during the typical chemical composition analysis of fine particles (e.g. ion chromatography), the existence of HMS could explain a significant fraction of

Quantifying aboveground forest carbon pools and fluxes from repeat LiDAR surveys

Treesearch

Andrew T. Hudak; Eva K. Strand; Lee A. Vierling; John C. Byrne; Jan U. H. Eitel; Sebastian Martinuzzi; Michael J. Falkowski

2012-01-01

Sound forest policy and management decisions to mitigate rising atmospheric CO2 depend upon accurate methodologies to quantify forest carbon pools and fluxes over large tracts of land. LiDAR remote sensing is a rapidly evolving technology for quantifying aboveground biomass and thereby carbon pools; however, little work has evaluated the efficacy of repeat LiDAR...

Particle aggregation during receptor-mediated endocytosis

NASA Astrophysics Data System (ADS)

Mao, Sheng; Kosmrlj, Andrej

Receptor-mediated endocytosis of particles is driven by large binding energy between ligands on particles and receptors on a membrane, which compensates for the membrane bending energy and for the cost due to the mixing entropy of receptors. While the receptor-mediated endocytosis of individual particle is well understood, much less is known about the joint entry of multiple particles. Here, we demonstrate that the endocytosis of multiple particles leads to a kinetically driven entropic attraction, which may cause the aggregation of particles observed in experiments. During the endocytosis particles absorb nearby receptors and thus produce regions, which are depleted of receptors. When such depleted regions start overlapping, the corresponding particles experience osmotic-like attractive entropic force. If the attractive force between particles is large enough to overcome the repulsive interaction due to membrane bending, then particles tend to aggregate provided that they are sufficiently close, such that they are not completely engulfed before they come in contact. We discuss the necessary conditions for the aggregation of cylindrical particles during receptor-mediated endocytosis and comment on the generalization to spherical particles.

Particle separator

DOEpatents

Hendricks, Charles D.

1990-01-01

Method and apparatus (10) are provided for separating and classifying particles (48,50,56) by dispersing the particles within a fluid (52) that is upwardly flowing within a cone-shaped pipe (12) that has its large end (20) above its small end (18). Particles of similar size and shape (48,50) migrate to individual levels (A,B) within the flowing fluid. As the fluid is deflected by a plate (42) at the top end of the pipe (12), the smallest particles are collected on a shelf-like flange (40). Ever larger particles are collected as the flow rate of the fluid is increased. To prevent particle sticking on the walls (14) of the pipe (12), additional fluid is caused to flow into the pipe (12) through holes (68) that are specifically provided for that purpose. Sticking is further prevented by high frequency vibrators (70) that are positioned on the apparatus (10).

Flash X-Ray measurements on the shock-induced dispersal of a dense particle curtain

DOE PAGES

Wagner, Justin L.; Kearney, Sean P.; Beresh, Steven J.; ...

2015-11-23

The interaction of a Mach 1.67 shock wave with a dense particle curtain is quantified using flash radiography. These new data provide a view of particle transport inside a compressible, dense gas–solid flow of high optical opacity. The curtain, composed of 115-µm glass spheres, initially spans 87 % of the test section width and has a streamwise thickness of about 2 mm. Radiograph intensities are converted to particle volume fraction distributions using the Beer–Lambert law. The mass in the particle curtain, as determined from the X-ray data, is in reasonable agreement with that given from a simpler method using amore » load cell and particle imaging. Following shock impingement, the curtain propagates downstream and the peak volume fraction decreases from about 23 to about 4 % over a time of 340 µs. The propagation occurs asymmetrically, with the downstream side of the particle curtain experiencing a greater volume fraction gradient than the upstream side, attributable to the dependence of particle drag on volume fraction. Bulk particle transport is quantified from the time-dependent center of mass of the curtain. Furthermore, the bulk acceleration of the curtain is shown to be greater than that predicted for a single 115-µm particle in a Mach 1.67 shock-induced flow.« less

Flash X-Ray measurements on the shock-induced dispersal of a dense particle curtain

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

Wagner, Justin L.; Kearney, Sean P.; Beresh, Steven J.

The interaction of a Mach 1.67 shock wave with a dense particle curtain is quantified using flash radiography. These new data provide a view of particle transport inside a compressible, dense gas–solid flow of high optical opacity. The curtain, composed of 115-µm glass spheres, initially spans 87 % of the test section width and has a streamwise thickness of about 2 mm. Radiograph intensities are converted to particle volume fraction distributions using the Beer–Lambert law. The mass in the particle curtain, as determined from the X-ray data, is in reasonable agreement with that given from a simpler method using amore » load cell and particle imaging. Following shock impingement, the curtain propagates downstream and the peak volume fraction decreases from about 23 to about 4 % over a time of 340 µs. The propagation occurs asymmetrically, with the downstream side of the particle curtain experiencing a greater volume fraction gradient than the upstream side, attributable to the dependence of particle drag on volume fraction. Bulk particle transport is quantified from the time-dependent center of mass of the curtain. Furthermore, the bulk acceleration of the curtain is shown to be greater than that predicted for a single 115-µm particle in a Mach 1.67 shock-induced flow.« less

Flash X-ray measurements on the shock-induced dispersal of a dense particle curtain

NASA Astrophysics Data System (ADS)

Wagner, Justin L.; Kearney, Sean P.; Beresh, Steven J.; DeMauro, Edward P.; Pruett, Brian O.

2015-12-01

The interaction of a Mach 1.67 shock wave with a dense particle curtain is quantified using flash radiography. These new data provide a view of particle transport inside a compressible, dense gas-solid flow of high optical opacity. The curtain, composed of 115-µm glass spheres, initially spans 87 % of the test section width and has a streamwise thickness of about 2 mm. Radiograph intensities are converted to particle volume fraction distributions using the Beer-Lambert law. The mass in the particle curtain, as determined from the X-ray data, is in reasonable agreement with that given from a simpler method using a load cell and particle imaging. Following shock impingement, the curtain propagates downstream and the peak volume fraction decreases from about 23 to about 4 % over a time of 340 µs. The propagation occurs asymmetrically, with the downstream side of the particle curtain experiencing a greater volume fraction gradient than the upstream side, attributable to the dependence of particle drag on volume fraction. Bulk particle transport is quantified from the time-dependent center of mass of the curtain. The bulk acceleration of the curtain is shown to be greater than that predicted for a single 115-µm particle in a Mach 1.67 shock-induced flow.

Quantifying soil respiration at landscape scales. Chapter 11

Treesearch

John B. Bradford; Michael G. Ryan

2008-01-01

Soil CO2, efflux, or soil respiration, represents a substantial component of carbon cycling in terrestrial ecosystems. Consequently, quantifying soil respiration over large areas and long time periods is an increasingly important goal. However, soil respiration rates vary dramatically in space and time in response to both environmental conditions...

Analysis of Alfvén eigenmode destabilization by energetic particles in Large Helical Device using a Landau-closure model

DOE PAGES

Varela, Jacobo Rodriguez; Spong, D. A.; Garcia, L.

2017-03-06

Here, energetic particle populations in nuclear fusion experiments can destabilize the Alfvén Eigenmodes through inverse Landau damping and couplings with gap modes in the shear Alfvén continua. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles. We add the Landau damping and resonant destabilization effects using a closure relation. We apply the model to study the Alfvén mode stability in the inward-shifted configurations of the Large Helical Device (LHD), performing a parametric analysis of the energetic particle β (more » $${{\\beta}_{f}}$$ ) in a range of realistic values, the ratios of the energetic particle thermal/Alfvén velocities ($${{V}_{\\text{th}}}/{{V}_{A0}}$$ ), the magnetic Lundquist numbers (S) and the toroidal modes (n). The n = 1 and n = 2 TAEs are destabilized, although the n = 3 and n = 4 TAEs are weakly perturbed. The most unstable configurations are associated with the density gradients of energetic particles in the plasma core: the TAEs are destabilized, even for small energetic particle populations, if their thermal velocity is lower than 0.4 times the Alfvén velocity. The frequency range of MHD bursts measured in the LHD are 50–70 kHz for the n = 1 and 60–80 kHz for the n = 2 TAE, which is consistent with the model predictions.« less

The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

NASA Astrophysics Data System (ADS)

Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

2006-12-01

Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

Quantitative single-particle digital autoradiography with α-particle emitters for targeted radionuclide therapy using the iQID camera

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

Miller, Brian W., E-mail: brian.miller@pnnl.gov; Frost, Sofia H. L.; Frayo, Shani L.

2015-07-15

Purpose: Alpha-emitting radionuclides exhibit a potential advantage for cancer treatments because they release large amounts of ionizing energy over a few cell diameters (50–80 μm), causing localized, irreparable double-strand DNA breaks that lead to cell death. Radioimmunotherapy (RIT) approaches using monoclonal antibodies labeled with α emitters may thus inactivate targeted cells with minimal radiation damage to surrounding tissues. Tools are needed to visualize and quantify the radioactivity distribution and absorbed doses to targeted and nontargeted cells for accurate dosimetry of all treatment regimens utilizing α particles, including RIT and others (e.g., Ra-223), especially for organs and tumors with heterogeneous radionuclidemore » distributions. The aim of this study was to evaluate and characterize a novel single-particle digital autoradiography imager, the ionizing-radiation quantum imaging detector (iQID) camera, for use in α-RIT experiments. Methods: The iQID camera is a scintillator-based radiation detection system that images and identifies charged-particle and gamma-ray/x-ray emissions spatially and temporally on an event-by-event basis. It employs CCD-CMOS cameras and high-performance computing hardware for real-time imaging and activity quantification of tissue sections, approaching cellular resolutions. In this work, the authors evaluated its characteristics for α-particle imaging, including measurements of intrinsic detector spatial resolutions and background count rates at various detector configurations and quantification of activity distributions. The technique was assessed for quantitative imaging of astatine-211 ({sup 211}At) activity distributions in cryosections of murine and canine tissue samples. Results: The highest spatial resolution was measured at ∼20 μm full width at half maximum and the α-particle background was measured at a rate as low as (2.6 ± 0.5) × 10{sup −4} cpm/cm{sup 2} (40 mm diameter detector area

Energetic-particle-induced geodesic acoustic mode.

PubMed

Fu, G Y

2008-10-31

A new energetic particle-induced geodesic acoustic mode (EGAM) is shown to exist. The mode frequency and mode structure are determined nonperturbatively by energetic particle kinetic effects. In particular the EGAM frequency is found to be substantially lower than the standard GAM frequency. The radial mode width is determined by the energetic particle drift orbit width and can be fairly large for high energetic particle pressure and large safety factor. These results are consistent with the recent experimental observation of the beam-driven n=0 mode in DIII-D.

Markedly enhanced direct radiative forcing of black carbon particles under polluted urban environments

NASA Astrophysics Data System (ADS)

Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti; Zeng, Liming; Shao, Min; Wu, Yusheng; Zheng, Jun; Wang, Yuan; Collins, Don; Zhang, Renyi

2016-04-01

Black carbon (BC) particles, produced from incomplete fossil fuel combustion and biomass burning, are ubiquitous in the atmosphere and have profound impacts on air quality, human health, weather, and climate. For example, in areas identified as aerosol hotspots, which include many urban centers and megacities worldwide, solar heating by BC particles has been shown to be comparable to warming due to the greenhouse gases2. Although BC represents a key short-lived climate forcer, its direct radiative forcing remains highly uncertain. In particular, the available results of absorption enhancement of BC particles during atmospheric aging are conflicting from the previous studies, leading to a large uncertainty in global radiative transfer calculation. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China and Houston, US, using a novel chamber approach. BC aging exhibits two distinct stages - initial transformation from a fractal to spherical morphology with little absorption variation and the subsequent growth of fully compact particles with a maximum absorption enhancement factor of 2.4. The variation in BC direct radiative forcing is highly dependent of the rate and timescale of aging, with an estimated increase of 0.45 (0.21 - 0.80) W m-2 from fresh to fully aged particles. Our results reveal a high climatic impact in polluted environments due to rapid aging and a clear distinction between urban cities in developed and developing countries for BC particles, highlighting a larger than recognized co-benefit in air quality improvement and climate protection by BC mediation.

Quantifying the impact of bathymetric changes on the hydrological regimes in a large floodplain lake: Poyang Lake

NASA Astrophysics Data System (ADS)

Yao, Jing; Zhang, Qi; Ye, Xuchun; Zhang, Dan; Bai, Peng

2018-06-01

The hydrological regime of a lake is largely dependent on its bathymetry. A dramatic water level reduction has occurred in Poyang Lake in recent years, coinciding with significant bed erosion. Few studies have focused on the influence of bathymetric changes on the hydrological regime in such a complex river-lake floodplain system. This study combined hydrological data and a physically based hydrodynamic model to quantify the influence of the bathymetric changes (1998-2010) on the water level spatiotemporal distribution in Poyang Lake, based on a dry year (2006), a wet year (2010) and an average year (2000-2010). The following conclusions can be drawn from the results of this study: (1) The bed erosion of the northern outlet channel averaged 3 m, resulting in a decrease in the water level by 1.2-2 m in the northern channels (the most significantly influenced areas) and approximately 0.3 m in the central lake areas during low-level periods. The water levels below 16 m and 14 m were significantly affected during the rising period and recession period, respectively. The water level reduction was enhanced due to lower water levels. (2) The water surface profiles adjusted, and the rising and recession rates of the water level increased by 0.5-3.1 cm/d at the lake outlet. The bathymetric influence extended across the entire lake due to the emptying effect, resulting in a change in the water level distribution. The average annual outflow increased by 6.8%. (3) The bathymetric changes contributed approximately 14.4% to the extreme low water level in autumn 2006 and enhanced the drought in the dry season. This study quantified the impact of the bathymetric changes on the lake water levels, thereby providing a better understanding of the potential effects of continued sand mining operations and providing scientific explanations for the considerable variations in the hydrological regimes of Poyang Lake. Moreover, this study attempts to provide a reference for the assessment of

Primary cosmic ray particles with z 35 (VVH particles). [very heavy particle detection by high altitude balloons

NASA Technical Reports Server (NTRS)

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

1972-01-01

Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high altitude balloon flights. From the analysis of 141 particle tracks recorded during a total exposure of 1.3 x 10 to the 7th power sq m ster.sec., a charge spectrum of the VVH particles has been derived.

Cross-linguistic patterns in the acquisition of quantifiers

PubMed Central

Cummins, Chris; Gavarró, Anna; Kuvač Kraljević, Jelena; Hrzica, Gordana; Grohmann, Kleanthes K.; Skordi, Athina; Jensen de López, Kristine; Sundahl, Lone; van Hout, Angeliek; Hollebrandse, Bart; Overweg, Jessica; Faber, Myrthe; van Koert, Margreet; Smith, Nafsika; Vija, Maigi; Zupping, Sirli; Kunnari, Sari; Morisseau, Tiffany; Rusieshvili, Manana; Yatsushiro, Kazuko; Fengler, Anja; Varlokosta, Spyridoula; Konstantzou, Katerina; Farby, Shira; Guasti, Maria Teresa; Vernice, Mirta; Okabe, Reiko; Isobe, Miwa; Crosthwaite, Peter; Hong, Yoonjee; Balčiūnienė, Ingrida; Ahmad Nizar, Yanti Marina; Grech, Helen; Gatt, Daniela; Cheong, Win Nee; Asbjørnsen, Arve; Torkildsen, Janne von Koss; Haman, Ewa; Miękisz, Aneta; Gagarina, Natalia; Puzanova, Julia; Anđelković, Darinka; Savić, Maja; Jošić, Smiljana; Slančová, Daniela; Kapalková, Svetlana; Barberán, Tania; Özge, Duygu; Hassan, Saima; Chan, Cecilia Yuet Hung; Okubo, Tomoya; van der Lely, Heather; Sauerland, Uli; Noveck, Ira

2016-01-01

Learners of most languages are faced with the task of acquiring words to talk about number and quantity. Much is known about the order of acquisition of number words as well as the cognitive and perceptual systems and cultural practices that shape it. Substantially less is known about the acquisition of quantifiers. Here, we consider the extent to which systems and practices that support number word acquisition can be applied to quantifier acquisition and conclude that the two domains are largely distinct in this respect. Consequently, we hypothesize that the acquisition of quantifiers is constrained by a set of factors related to each quantifier’s specific meaning. We investigate competence with the expressions for “all,” “none,” “some,” “some…not,” and “most” in 31 languages, representing 11 language types, by testing 768 5-y-old children and 536 adults. We found a cross-linguistically similar order of acquisition of quantifiers, explicable in terms of four factors relating to their meaning and use. In addition, exploratory analyses reveal that language- and learner-specific factors, such as negative concord and gender, are significant predictors of variation. PMID:27482119

Quantifiers more or less quantify online: ERP evidence for partial incremental interpretation

PubMed Central

Urbach, Thomas P.; Kutas, Marta

2010-01-01

Event-related brain potentials were recorded during RSVP reading to test the hypothesis that quantifier expressions are incrementally interpreted fully and immediately. In sentences tapping general knowledge (Farmers grow crops/worms as their primary source of income), Experiment 1 found larger N400s for atypical (worms) than typical objects (crops). Experiment 2 crossed object typicality with non-logical subject-noun phrase quantifiers (most, few). Off-line plausibility ratings exhibited the crossover interaction predicted by full quantifier interpretation: Most farmers grow crops and Few farmers grow worms were rated more plausible than Most farmers grow worms and Few farmers grow crops. Object N400s, although modulated in the expected direction, did not reverse. Experiment 3 replicated these findings with adverbial quantifiers (Farmers often/rarely grow crops/worms). Interpretation of quantifier expressions thus is neither fully immediate nor fully delayed. Furthermore, object atypicality was associated with a frontal slow positivity in few-type/rarely quantifier contexts, suggesting systematic processing differences among quantifier types. PMID:20640044

Buckling vs. particle desorption in a particle-covered drop subject to compressive surface stresses: a simulation study.

PubMed

Gu, Chuan; Botto, Lorenzo

2018-01-31

Predicting the behaviour of particle-covered fluid interfaces under compression has implications in several fields. The surface-tension driven adhesion of particles to drops and bubbles is exploited for example to enhance the stability of foams and emulsion and develop new generation materials. When a particle-covered fluid interface is compressed, one can observe either smooth buckling or particle desorption from the interface. The microscopic mechanisms leading to the buckling-to-desorption transition are not fully understood. In this paper we simulate a spherical drop covered by a monolayer of spherical particles. The particle-covered interface is subject to time-dependent compressive surface stresses that mimic the slow deflation of the drop. The buckling-to-desorption transition depends in a non-trivial way on three non-dimensional parameters: the ratio Π s /γ of particle-induced surface pressure and bare surface tension, the ratio a/R of particle and drop radii, and the parameter f characterising the strength of adhesion of each particle to the interface. Based on the insights from the simulations, we propose a configuration diagram describing the effect of these controlling parameters. We find that particle desorption is highly correlated with a mechanical instability that produces small-scale undulations of the monolayer of the order of the particle size that grow when the surface pressure is sufficiently large. We argue that the large local curvature associated with these small undulations can produce large normal forces, enhancing the probability of desorption.

Ion Transport and Acceleration at Dipolarization Fronts: High-Resolution MHD/Test-Particle Simulations

NASA Astrophysics Data System (ADS)

Ukhorskiy, A. Y.; Sorathia, K.; Merkin, V. G.; Sitnov, M. I.; Mitchell, D. G.; Wiltberger, M. J.; Lyon, J.

2017-12-01

Much of plasma heating and transport from the magnetotail into the inner magnetosphere occurs in the form of mesoscale discrete injections associated with sharp dipolarizations of magnetic field (dipolarization fronts). In this study we investigate the mechanisms of ion acceleration at dipolarization fronts in a high-resolution global magnetospheric MHD model (LFM). We use large-scale three-dimensional test-particle simulations (CHIMP) to address the following science questions: 1) what are the characteristic scales of dipolarization regions that can stably trap ions? 2) what role does the trapping play in ion transport and acceleration? 3) how does it depend on particle energy and distance from Earth? 4) to what extent ion acceleration is adiabatic? High-resolution LFM was run using idealized solar wind conditions with fixed nominal values of density and velocity and a southward IMF component of -5 nT. To simulate ion interaction with dipolarization fronts, a large ensemble of test particles distributed in energy, pitch-angle, and gyrophase was initialized inside one of the LFM dipolarization channels in the magnetotail. Full Lorentz ion trajectories were then computed over the course of the front inward propagation from the distance of 17 to 6 Earth radii. A large fraction of ions with different initial energies stayed in phase with the front over the entire distance. The effect of magnetic trapping at different energies was elucidated with a correlation of the ion guiding center and the ExB drift velocities. The role of trapping in ion energization was quantified by comparing the partial pressure of ions that exhibit trapping to the pressure of all trapped ions.

Quantifying functional mobility progress for chronic disease management.

PubMed

Boyle, Justin; Karunanithi, Mohan; Wark, Tim; Chan, Wilbur; Colavitti, Christine

2006-01-01

A method for quantifying improvements in functional mobility is presented based on patient-worn accelerometer devices. For patients with cardiovascular, respiratory, or other chronic disease, increasing the amount of functional mobility is a large component of rehabilitation programs. We have conducted an observational trial on the use of accelerometers for quantifying mobility improvements in a small group of chronic disease patients (n=15, 48 - 86 yrs). Cognitive impairments precluded complex instrumentation of patients, and movement data was obtained from a single 2-axis accelerometer device worn at the hip. In our trial, movement data collected from accelerometer devices was classified into Lying vs Sitting/Standing vs Walking/Activity movements. This classification enabled the amount of walking to be quantified and graphically presented to clinicians and carers for feedback on exercise efficacy. Presenting long term trends in this data to patients also provides valuable feedback for self managed care and assisting with compliance.

A Large-Particle Monte Carlo Code for Simulating Non-Linear High-Energy Processes Near Compact Objects

NASA Technical Reports Server (NTRS)

Stern, Boris E.; Svensson, Roland; Begelman, Mitchell C.; Sikora, Marek

1995-01-01

High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In this paper, we present the latest version of the LP method and compare it with the other methods. The efficiency of the method in treating geometrically complex problems is illustrated by showing results of simulations of 1D, 2D and 3D systems. The method is shown to be powerful enough to treat non-spherical geometries, including such effects as bulk motion of the background plasma, reflection of radiation from cold matter, and anisotropic distributions of radiating particles. It can therefore be applied to simulate high-energy processes in such astrophysical systems as accretion discs with coronae, relativistic jets, pulsar magnetospheres and gamma-ray bursts.

Quantifying Semantic Linguistic Maturity in Children.

PubMed

Hansson, Kristina; Bååth, Rasmus; Löhndorf, Simone; Sahlén, Birgitta; Sikström, Sverker

2016-10-01

We propose a method to quantify semantic linguistic maturity (SELMA) based on a high dimensional semantic representation of words created from the co-occurrence of words in a large text corpus. The method was applied to oral narratives from 108 children aged 4;0-12;10. By comparing the SELMA measure with maturity ratings made by human raters we found that SELMA predicted the rating of semantic maturity made by human raters over and above the prediction made using a child's age and number of words produced. We conclude that the semantic content of narratives changes in a predictable pattern with children's age and argue that SELMA is a measure quantifying semantic linguistic maturity. The study opens up the possibility of using quantitative measures for studying the development of semantic representation in children's narratives, and emphasizes the importance of word co-occurrences for understanding the development of meaning.

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-06-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behavior of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, although large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations. In general, particle ignition is a competition between particle heating (which is influenced by particle morphology, size, number density and the local thermodynamic history) and expansion cooling of the products.

Accurate quantification of magnetic particle properties by intra-pair magnetophoresis for nanobiotechnology

NASA Astrophysics Data System (ADS)

van Reenen, Alexander; Gao, Yang; Bos, Arjen H.; de Jong, Arthur M.; Hulsen, Martien A.; den Toonder, Jaap M. J.; Prins, Menno W. J.

2013-07-01

The application of magnetic particles in biomedical research and in-vitro diagnostics requires accurate characterization of their magnetic properties, with single-particle resolution and good statistics. Here, we report intra-pair magnetophoresis as a method to accurately quantify the field-dependent magnetic moments of magnetic particles and to rapidly generate histograms of the magnetic moments with good statistics. We demonstrate our method with particles of different sizes and from different sources, with a measurement precision of a few percent. We expect that intra-pair magnetophoresis will be a powerful tool for the characterization and improvement of particles for the upcoming field of particle-based nanobiotechnology.

Experimental investigations of mechanical and reaction responses for drop-weight impacted energetic particles

NASA Astrophysics Data System (ADS)

Bao, Xiao-Wei; Wu, Yan-Qing; Wang, Ming-Yang; Huang, Feng-Lei

2017-02-01

Low-velocity drop-weight impact experiments on individual and multiple Cyclotetramethylene tetranitramine (HMX) energetic particles were performed using a modified drop-weight machine equipped with high-speed photography components. Multiple particles experienced more severe burning reactions than an individual particle. Comparisons between impacted salt and HMX particle show that jetting in HMX is mainly due to the motion of fragmented particles driven by gaseous reaction products. Velocity of jetting, flame propagation, and area expansion were measured via image processing, making it possible to quantify the chemical reaction or mechanical deformation violence at different stages.

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.

Analysis of Alfvén eigenmode destabilization by energetic particles in Large Helical Device using a Landau-closure model

NASA Astrophysics Data System (ADS)

Varela, J.; Spong, D. A.; Garcia, L.

2017-04-01

Energetic particle populations in nuclear fusion experiments can destabilize the Alfvén Eigenmodes through inverse Landau damping and couplings with gap modes in the shear Alfvén continua. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles. We add the Landau damping and resonant destabilization effects using a closure relation. We apply the model to study the Alfvén mode stability in the inward-shifted configurations of the Large Helical Device (LHD), performing a parametric analysis of the energetic particle β ({βf} ) in a range of realistic values, the ratios of the energetic particle thermal/Alfvén velocities ({{V}\\text{th}}/{{V}A0} ), the magnetic Lundquist numbers (S) and the toroidal modes (n). The n  =  1 and n  =  2 TAEs are destabilized, although the n  =  3 and n  =  4 TAEs are weakly perturbed. The most unstable configurations are associated with the density gradients of energetic particles in the plasma core: the TAEs are destabilized, even for small energetic particle populations, if their thermal velocity is lower than 0.4 times the Alfvén velocity. The frequency range of MHD bursts measured in the LHD are 50-70 kHz for the n  =  1 and 60-80 kHz for the n  =  2 TAE, which is consistent with the model predictions. ).

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David L.; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-12-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behaviour of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, whereas large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations after a delay. Hence the charge geometry, as well as particle morphology, influences the reaction behaviour of the particles.

A hybrid binary particle swarm optimization for large capacitated multi item multi level lot sizing (CMIMLLS) problem

NASA Astrophysics Data System (ADS)

Mishra, S. K.; Sahithi, V. V. D.; Rao, C. S. P.

2016-09-01

The lot sizing problem deals with finding optimal order quantities which minimizes the ordering and holding cost of product mix. when multiple items at multiple levels with all capacity restrictions are considered, the lot sizing problem become NP hard. Many heuristics were developed in the past have inevitably failed due to size, computational complexity and time. However the authors were successful in the development of PSO based technique namely iterative improvement binary particles swarm technique to address very large capacitated multi-item multi level lot sizing (CMIMLLS) problem. First binary particle Swarm Optimization algorithm is used to find a solution in a reasonable time and iterative improvement local search mechanism is employed to improvise the solution obtained by BPSO algorithm. This hybrid mechanism of using local search on the global solution is found to improve the quality of solutions with respect to time thus IIBPSO method is found best and show excellent results.

What's Next for Particle Physics?

NASA Astrophysics Data System (ADS)

White, Martin

2017-10-01

Following the discovery of the Higgs boson in 2012, particle physics has entered its most exciting and crucial period for over 50 years. In this book, I first summarise our current understanding of particle physics, and why this knowledge is almost certainly incomplete. We will then see that the Large Hadron Collider provides the means to search for the next theory of particle physics by performing precise measurements of the Higgs boson, and by looking directly for particles that can solve current cosmic mysteries such as the nature of dark matter. Finally, I will anticipate the next decade of particle physics by placing the Large Hadron Collider within the wider context of other experiments. The results expected over the next ten years promise to transform our understanding of what the Universe is made of and how it came to be.

INTERACTION BETWEEN TWO CORONAL MASS EJECTIONS IN THE 2013 MAY 22 LARGE SOLAR ENERGETIC PARTICLE EVENT

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

Ding, Liu-Guan; Xu, Fei; Gu, Bin

We investigate the eruption and interaction of two coronal mass ejections (CMEs) during the large 2013 May 22 solar energetic particle event using multiple spacecraft observations. Two CMEs, having similar propagation directions, were found to erupt from two nearby active regions (ARs), AR11748 and AR11745, at ∼08:48 UT and ∼13:25 UT, respectively. The second CME was faster than the first CME. Using the graduated cylindrical shell model, we reconstructed the propagation of these two CMEs and found that the leading edge of the second CME caught up with the trailing edge of the first CME at a height of ∼6 solar radii. Aftermore » about two hours, the leading edges of the two CMEs merged at a height of ∼20 solar radii. Type II solar radio bursts showed strong enhancement during this two hour period. Using the velocity dispersion method, we obtained the solar particle release (SPR) time and the path length for energetic electrons. Further assuming that energetic protons propagated along the same interplanetary magnetic field, we also obtained the SPR time for energetic protons, which were close to that of electrons. These release times agreed with the time when the second CME caught up with the trailing edge of the first CME, indicating that the CME-CME interaction (and shock-CME interaction) plays an important role in the process of particle acceleration in this event.« less

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 micrometer 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 micrometer 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 form the thermal black body radiation. Recorded flame images were digitized and employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishing 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.

Quantifying Sulfate, Organics, and Lubrication Oil in Particles Emitted from Military Aircraft Engines

DTIC Science & Technology

2012-10-01

Measurements. Part 1: Theory. Aerosol Sci. Tech., 38, 1185-1205 Finlayson-Pitts, B. J. and Pitts, J. N. 1997. Tropospheric air pollution: Ozone ...2004). Wetting and Hydration of Insoluble Soot Particles in the Upper Troposphere . J. Environ. Monitoring, 6:939-945. Petzold, A., Gysel, M...nanoparticles: role of ambient ionization in tropospheric aerosol formation. Journal of Geophysical Research, 106(5): 4797–4814. Yu, F. (2005). Quasi

The thermal aggregation of ovalbumin as large particles decreases its allergenicity for egg allergic patients and in a murine model.

PubMed

Claude, M; Lupi, R; Bouchaud, G; Bodinier, M; Brossard, C; Denery-Papini, S

2016-07-15

Most egg-allergic children can tolerate extensively cooked eggs. Ovalbumin, a major allergen in egg whites, is prone to aggregate upon heating. This study compares ovalbumin's allergenicity when it is aggregated as large particles to ovalbumin in its native form. Immunoglobulins (Ig)-binding and the degranulation capacities of native and aggregated ovalbumin were measured with sera from egg-allergic children and from mice sensitized to native or aggregated ovalbumin. The influence of ovalbumin structure on Ig production upon sensitization and elicitation potency by challenge was also studied. We showed that heat aggregation of ovalbumin as large particles enhances IgG production and promotes IgG2a production (a shift toward the T helper 1 profile). Aggregated ovalbumin displayed lower Ig-binding and basophil-activation capacities for sera from both allergic patients and mice. This work illustrates the links between ovalbumin structure after heating and allergenicity potential using parameters from both the sensitization and elicitation phases of the allergic reaction. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-levels of microplastic pollution in a large, remote, mountain lake.

PubMed

Free, Christopher M; Jensen, Olaf P; Mason, Sherri A; Eriksen, Marcus; Williamson, Nicholas J; Boldgiv, Bazartseren

2014-08-15

Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km(-2), Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics. Copyright © 2014 Elsevier Ltd. All rights reserved.

NanoXCT: a novel technique to probe the internal architecture of pharmaceutical particles.

PubMed

Wong, Jennifer; D'Sa, Dexter; Foley, Matthew; Chan, John Gar Yan; Chan, Hak-Kim

2014-11-01

To demonstrate the novel application of nano X-ray computed tomography (NanoXCT) for visualizing and quantifying the internal structures of pharmaceutical particles. An Xradia NanoXCT-100, which produces ultra high-resolution and non-destructive imaging that can be reconstructed in three-dimensions (3D), was used to characterize several pharmaceutical particles. Depending on the particle size of the sample, NanoXCT was operated in Zernike Phase Contrast (ZPC) mode using either: 1) large field of view (LFOV), which has a two-dimensional (2D) spatial resolution of 172 nm; or 2) high resolution (HRES) that has a resolution of 43.7 nm. Various pharmaceutical particles with different physicochemical properties were investigated, including raw (2-hydroxypropyl)-beta-cyclodextrin (HβCD), poly (lactic-co-glycolic) acid (PLGA) microparticles, and spray-dried particles that included smooth and nanomatrix bovine serum albumin (BSA), lipid-based carriers, and mannitol. Both raw HβCD and PLGA microparticles had a network of voids, whereas spray-dried smooth BSA and mannitol generally had a single void. Lipid-based carriers and nanomatrix BSA particles resulted in low quality images due to high noise-to-signal ratio. The quantitative capabilities of NanoXCT were also demonstrated where spray-dried mannitol was found to have an average void volume of 0.117 ± 0.247 μm(3) and average void-to-material percentage of 3.5%. The single PLGA particle had values of 1993 μm(3) and 59.3%, respectively. This study reports the first series of non-destructive 3D visualizations of inhalable pharmaceutical particles. Overall, NanoXCT presents a powerful tool to dissect and observe the interior of pharmaceutical particles, including those of a respirable size.

Quantifying entanglement with witness operators

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

Brandao, Fernando G.S.L.

2005-08-15

We present a unifying approach to the quantification of entanglement based on entanglement witnesses, which includes several already established entanglement measures such as the negativity, the concurrence, and the robustness of entanglement. We then introduce an infinite family of new entanglement quantifiers, having as its limits the best separable approximation measure and the generalized robustness. Gaussian states, states with symmetry, states constrained to super-selection rules, and states composed of indistinguishable particles are studied under the view of the witnessed entanglement. We derive new bounds to the fidelity of teleportation d{sub min}, for the distillable entanglement E{sub D} and for themore » entanglement of formation. A particular measure, the PPT-generalized robustness, stands out due to its easy calculability and provides sharper bounds to d{sub min} and E{sub D} than the negativity in most of the states. We illustrate our approach studying thermodynamical properties of entanglement in the Heisenberg XXX and dimerized models.« less

Estimate of main local sources to ambient ultrafine particle number concentrations in an urban area

NASA Astrophysics Data System (ADS)

Rahman, Md Mahmudur; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

2017-09-01

Quantifying and apportioning the contribution of a range of sources to ultrafine particles (UFPs, D < 100 nm) is a challenge due to the complex nature of the urban environments. Although vehicular emissions have long been considered one of the major sources of ultrafine particles in urban areas, the contribution of other major urban sources is not yet fully understood. This paper aims to determine and quantify the contribution of local ground traffic, nucleated particle (NP) formation and distant non-traffic (e.g. airport, oil refineries, and seaport) sources to the total ambient particle number concentration (PNC) in a busy, inner-city area in Brisbane, Australia using Bayesian statistical modelling and other exploratory tools. The Bayesian model was trained on the PNC data on days where NP formations were known to have not occurred, hourly traffic counts, solar radiation data, and smooth daily trend. The model was applied to apportion and quantify the contribution of NP formations and local traffic and non-traffic sources to UFPs. The data analysis incorporated long-term measured time-series of total PNC (D ≥ 6 nm), particle number size distributions (PSD, D = 8 to 400 nm), PM2.5, PM10, NOx, CO, meteorological parameters and traffic counts at a stationary monitoring site. The developed Bayesian model showed reliable predictive performances in quantifying the contribution of NP formation events to UFPs (up to 4 × 104 particles cm- 3), with a significant day to day variability. The model identified potential NP formation and no-formations days based on PNC data and quantified the sources contribution to UFPs. Exploratory statistical analyses show that total mean PNC during the middle of the day was up to 32% higher than during peak morning and evening traffic periods, which were associated with NP formation events. The majority of UFPs measured during the peak traffic and NP formation periods were between 30-100 nm and smaller than 30 nm, respectively. To date

Global views of energetic particle precipitation and their sources: Combining large-scale models with observations during the 21-22 January 2005 magnetic storm (Invited)

NASA Astrophysics Data System (ADS)

Kozyra, J. U.; Brandt, P. C.; Cattell, C. A.; Clilverd, M.; de Zeeuw, D.; Evans, D. S.; Fang, X.; Frey, H. U.; Kavanagh, A. J.; Liemohn, M. W.; Lu, G.; Mende, S. B.; Paxton, L. J.; Ridley, A. J.; Rodger, C. J.; Soraas, F.

2010-12-01

Energetic ions and electrons that precipitate into the upper atmosphere from sources throughout geospace carry the influences of space weather disturbances deeper into the atmosphere, possibly contributing to climate variability. The three-dimensional atmospheric effects of these precipitating particles are a function of the energy and species of the particles, lifetimes of reactive species generated during collisions in the atmosphere, the nature of the driving space weather disturbance, and the large-scale transport properties (meteorology) of the atmosphere in the region of impact. Unraveling the features of system-level coupling between solar magnetic variability, space weather and stratospheric dynamics requires a global view of the precipitation, along with its temporal and spatial variation. However, observations of particle precipitation at the system level are sparse and incomplete requiring they be combined with other observations and with large-scale models to provide the global context that is needed to accelerate progress. We compare satellite and ground-based observations of geospace conditions and energetic precipitation (at ring current, radiation belt and auroral energies) to a simulation of the geospace environment during 21-22 January 2005 by the BATS-R-US MHD model coupled with a self-consistent ring current solution. The aim is to explore the extent to which regions of particle precipitation track global magnetic field distortions and ways in which global models enhance our understanding of linkages between solar wind drivers and evolution of energetic particle precipitation.

Gravity influence on the clustering of charged particles in turbulence

NASA Astrophysics Data System (ADS)

Lu, Jiang; Nordsiek, Hansen; Shaw, Raymond

2010-11-01

We report results aimed at studying the interactions of bidisperse charged inertial particles in homogeneous, isotropic turbulence, under the influence of gravitational settling. We theoretically and experimentally investigate the impact of gravititational settling on particle clustering, which is quantified by the radial distribution function (RDF). The theory is based on a drift-diffusion (Fokker-Planck) model with gravitational settling appearing as a diffusive term depending on a dimensionless settling parameter. The experiments are carried out in a laboratory chamber with nearly homogeneous, isotropic turbulence in which the flow is seeded with charged particles and digital holography used to obtain 3D particle positions and velocities. The derived radial distribution function for bidisperse settling charged particles is compared to the experimental RDFs.

Solar energetic particle anisotropies and insights into particle transport

NASA Astrophysics Data System (ADS)

Leske, R. A.; Cummings, A. C.; Cohen, C. M. S.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; Rosenvinge, T. T. von

2016-03-01

As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.

Interaction of Multiple Particles with a Solidification Front: From Compacted Particle Layer to Particle Trapping.

PubMed

Saint-Michel, Brice; Georgelin, Marc; Deville, Sylvain; Pocheau, Alain

2017-06-13

The interaction of solidification fronts with objects such as particles, droplets, cells, or bubbles is a phenomenon with many natural and technological occurrences. For an object facing the front, it may yield various fates, from trapping to rejection, with large implications regarding the solidification pattern. However, whereas most situations involve multiple particles interacting with each other and the front, attention has focused almost exclusively on the interaction of a single, isolated object with the front. Here we address experimentally the interaction of multiple particles with a solidification front by performing solidification experiments of a monodisperse particle suspension in a Hele-Shaw cell with precise control of growth conditions and real-time visualization. We evidence the growth of a particle layer ahead of the front at a close-packing volume fraction, and we document its steady-state value at various solidification velocities. We then extend single-particle models to the situation of multiple particles by taking into account the additional force induced on an entering particle by viscous friction in the compacted particle layer. By a force balance model this provides an indirect measure of the repelling mean thermomolecular pressure over a particle entering the front. The presence of multiple particles is found to increase it following a reduction of the thickness of the thin liquid film that separates particles and front. We anticipate the findings reported here to provide a relevant basis to understand many complex solidification situations in geophysics, engineering, biology, or food engineering, where multiple objects interact with the front and control the resulting solidification patterns.

A Large-scale Plume in an X-class Solar Flare

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

Fleishman, Gregory D.; Nita, Gelu M.; Gary, Dale E.

Ever-increasing multi-frequency imaging of solar observations suggests that solar flares often involve more than one magnetic fluxtube. Some of the fluxtubes are closed, while others can contain open fields. The relative proportion of nonthermal electrons among those distinct loops is highly important for understanding energy release, particle acceleration, and transport. The access of nonthermal electrons to the open field is also important because the open field facilitates the solar energetic particle (SEP) escape from the flaring site, and thus controls the SEP fluxes in the solar system, both directly and as seed particles for further acceleration. The large-scale fluxtubes aremore » often filled with a tenuous plasma, which is difficult to detect in either EUV or X-ray wavelengths; however, they can dominate at low radio frequencies, where a modest component of nonthermal electrons can render the source optically thick and, thus, bright enough to be observed. Here we report the detection of a large-scale “plume” at the impulsive phase of an X-class solar flare, SOL2001-08-25T16:23, using multi-frequency radio data from Owens Valley Solar Array. To quantify the flare’s spatial structure, we employ 3D modeling utilizing force-free-field extrapolations from the line of sight SOHO /MDI magnetograms with our modeling tool GX-Simulator. We found that a significant fraction of the nonthermal electrons that accelerated at the flare site low in the corona escapes to the plume, which contains both closed and open fields. We propose that the proportion between the closed and open fields at the plume is what determines the SEP population escaping into interplanetary space.« less

Interaction of DNA bases with silver nanoparticles: assembly quantified through SPRS and SERS.

PubMed

Basu, Soumen; Jana, Subhra; Pande, Surojit; Pal, Tarasankar

2008-05-15

Colloidal silver nanoparticles were prepared by reducing silver nitrate with sodium borohydride. The synthesized silver particles show an intense surface plasmon band in the visible region. The work reported here describes the interaction between nanoscale silver particles and various DNA bases (adenine, guanine, cytosine, and thymine), which are used as molecular linkers because of their biological significance. In colloidal solutions, the color of silver nanoparticles may range from red to purple to orange to blue, depending on the degree of aggregation as well as the orientation of the individual particles within the aggregates. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and absorption spectroscopy were used to characterize the assemblies. DNA base-induced differential silver nanoparticle aggregation was quantified from the peak separation (relates to color) of surface plasmon resonance spectroscopy (SPRS) and the signal intensity of surface-enhanced Raman scattering (SERS), which rationalize the extent of silver-nucleobase interactions.

Modeling Boulder Transport by Smooth Particle Hydrodynamics

NASA Astrophysics Data System (ADS)

Karpytchev, M.

2017-12-01

Large coastal boulders are often believed to have been transported by strong tsunami andstorm waves. Understanding and quantifying the boulder transport processes is, therefore,crucial for evaluation of strength and timing of the past tsunamis and storms. Over the last10-15 year, a series of studies have obtained estimates of basic wave parameters neededto set in motion a boulder of given size, shape and mass by using simplified paramaterizationsof fluid-particle interactions. Although, parameterizing the principal hydraulic forces drivingboulder transport was succefull in reproducing effects of several historical tsunamis, someimportant details about initiation of boulder motion and the contribution of coastal wavetransformations as well as of suspended sediment to enhancing coastal currents are still lacking.These essentially non-linear processes can be particularly important for distingushing, in everyparticular case, whether it is a storm wave or a tsunami (or both) that was capable to transportspecific boulder to a given site.In this study, we employ the Smooth Particle Hydrodynamics (SPH) method in orderto get new insights on interaction of waves with boulders in the nearshore area.We first compare the SPH predictions with available laboratory experiments and thenexplore the effects of realistic 3D coastal bathymetry, non-linear behaviour of coastal waves,boulders shape and the impact of bedload and suspended sediment on dislodgement and initiationof boulder transport.

Development and application of a particle-particle particle-mesh Ewald method for dispersion interactions.

PubMed

Isele-Holder, Rolf E; Mitchell, Wayne; Ismail, Ahmed E

2012-11-07

For inhomogeneous systems with interfaces, the inclusion of long-range dispersion interactions is necessary to achieve consistency between molecular simulation calculations and experimental results. For accurate and efficient incorporation of these contributions, we have implemented a particle-particle particle-mesh Ewald solver for dispersion (r(-6)) interactions into the LAMMPS molecular dynamics package. We demonstrate that the solver's O(N log N) scaling behavior allows its application to large-scale simulations. We carefully determine a set of parameters for the solver that provides accurate results and efficient computation. We perform a series of simulations with Lennard-Jones particles, SPC/E water, and hexane to show that with our choice of parameters the dependence of physical results on the chosen cutoff radius is removed. Physical results and computation time of these simulations are compared to results obtained using either a plain cutoff or a traditional Ewald sum for dispersion.

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.

Real-time quantitative PCR for retrovirus-like particle quantification in CHO cell culture.

PubMed

de Wit, C; Fautz, C; Xu, Y

2000-09-01

Chinese hamster ovary (CHO) cells have been widely used to manufacture recombinant proteins intended for human therapeutic uses. Retrovirus-like particles, which are apparently defective and non-infectious, have been detected in all CHO cells by electron microscopy (EM). To assure viral safety of CHO cell-derived biologicals, quantification of retrovirus-like particles in production cell culture and demonstration of sufficient elimination of such retrovirus-like particles by the down-stream purification process are required for product market registration worldwide. EM, with a detection limit of 1x10(6) particles/ml, is the standard retrovirus-like particle quantification method. The whole process, which requires a large amount of sample (3-6 litres), is labour intensive, time consuming, expensive, and subject to significant assay variability. In this paper, a novel real-time quantitative PCR assay (TaqMan assay) has been developed for the quantification of retrovirus-like particles. Each retrovirus particle contains two copies of the viral genomic particle RNA (pRNA) molecule. Therefore, quantification of retrovirus particles can be achieved by quantifying the pRNA copy number, i.e. every two copies of retroviral pRNA is equivalent to one retrovirus-like particle. The TaqMan assay takes advantage of the 5'-->3' exonuclease activity of Taq DNA polymerase and utilizes the PRISM 7700 Sequence Detection System of PE Applied Biosystems (Foster City, CA, U.S.A.) for automated pRNA quantification through a dual-labelled fluorogenic probe. The TaqMan quantification technique is highly comparable to the EM analysis. In addition, it offers significant advantages over the EM analysis, such as a higher sensitivity of less than 600 particles/ml, greater accuracy and reliability, higher sample throughput, more flexibility and lower cost. Therefore, the TaqMan assay should be used as a substitute for EM analysis for retrovirus-like particle quantification in CHO cell

Investigation of electric charge on inertial particle dynamics in turbulence

NASA Astrophysics Data System (ADS)

Lu, Jiang; Shaw, Raymond

2014-11-01

The behavior of electrically charged, inertial particles in homogeneous, isotropic turbulence is investigated. Both like-charged and oppositely-charged particle interactions are considered. Direct numerical simulations (DNS) of turbulence in a periodic box using the pseudospectral numerical method are performed, with Lagrangian tracking of the particles. We study effects of mutual electrostatic repulsion and attraction on the particle dynamics, as quantified by the radial distribution function (RDF) and the radial relative velocity. For the like-charged particle case, the Coulomb force leads to a short range repulsion behavior and an RDF reminiscent of that for a dilute gas. For the oppositely-charged particle case, the Coulomb force increases the RDF beyond that already occurring for neutral inertial particles. For both cases, the relative velocities are calculated as a function of particle separation distance and show distinct deviations from the expected scaling within the dissipation range. This research was supported by NASA Grant NNX113AF90G.

The stochastic dynamics of intermittent porescale particle motion

NASA Astrophysics Data System (ADS)

Dentz, Marco; Morales, Veronica; Puyguiraud, Alexandre; Gouze, Philippe; Willmann, Matthias; Holzner, Markus

2017-04-01

Numerical and experimental data for porescale particle dynamics show intermittent patterns in Lagrangian velocities and accelerations, which manifest in long time intervals of low and short durations of high velocities [1, 2]. This phenomenon is due to the spatial persistence of particle velocities on characteristic heterogeneity length scales. In order to systematically quantify these behaviors and extract the stochastic dynamics of particle motion, we focus on the analysis of Lagrangian velocities sampled equidistantly along trajectories [3]. This method removes the intermittency observed under isochrone sampling. The space-Lagrangian velocity series can be quantified by a Markov process that is continuous in distance along streamline. It is fully parameterized in terms of the flux-weighted Eulerian velocity PDF and the characteristic pore-length. The resulting stochastic particle motion describes a continuous time random walk (CTRW). This approach allows for the process based interpretation of experimental and numerical porescale velocity, acceleration and displacement data. It provides a framework for the characterization and upscaling of particle transport and dispersion from the pore to the Darcy-scale based on the medium geometry and Eulerian flow attributes. [1] P. De Anna, T. Le Borgne, M. Dentz, A.M. Tartakovsky, D. Bolster, and P. Davy, "Flow intermittency, dispersion, and correlated continuous time random walks in porous media," Phys. Rev. Lett. 110, 184502 (2013). [2] M. Holzner, V. L. Morales, M. Willmann, and M. Dentz, "Intermittent Lagrangian velocities and accelerations in three- dimensional porous medium flow," Phys. Rev. E 92, 013015 (2015). [3] M. Dentz, P. K. Kang, A. Comolli, T. Le Borgne, and D. R. Lester, "Continuous time random walks for the evolution of Lagrangian velocities," Phys. Rev. Fluids (2016).

Enhancement of particle-induced viscous fingering in bidisperse suspensions

NASA Astrophysics Data System (ADS)

Xu, Feng; Lee, Sungyon

2017-11-01

The novel particle-induced fingering instability is observed when bidisperse particle suspensions displace air in a Hele-Shaw cell. Leading to the instability, we observe that larger particles consistently enrich the fluid-fluid interface at a faster rate than the small particles. This size-dependent enrichment of the interface leads to an earlier onset of the fingering instability for bidisperse suspensions, compared to their monodisperse counterpart. Careful experiments are carried out by either systematically varying the ratio of large to small particles at fixed total concentrations, or by changing the total concentrations while the large particle concentrations are held constant. Experimental results show that the presence of large particle causes the instability to occur at concentrations as much as 5% lower than the pure small particle case. We also discuss the physical mechanism that drives the enrichment and the subsequent instability based on the modified suspension balance model.

Modeling Sediment Transport Using a Lagrangian Particle Tracking Algorithm Coupled with High-Resolution Large Eddy Simulations: a Critical Analysis of Model Limits and Sensitivity

NASA Astrophysics Data System (ADS)

Garcia, M. H.

2016-12-01

Modeling Sediment Transport Using a Lagrangian Particle Tracking Algorithm Coupled with High-Resolution Large Eddy Simulations: a Critical Analysis of Model Limits and Sensitivity Som Dutta1, Paul Fischer2, Marcelo H. Garcia11Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Il, 61801 2Department of Computer Science and Department of MechSE, University of Illinois at Urbana-Champaign, Urbana, Il, 61801 Since the seminal work of Niño and Garcia [1994], one-way coupled Lagrangian particle tracking has been used extensively for modeling sediment transport. Over time, the Lagrangian particle tracking method has been coupled with Eulerian flow simulations, ranging from Reynolds Averaged Navier-Stokes (RANS) based models to Detached Eddy Simulations (DES) [Escauriaza and Sotiropoulos, 2011]. Advent of high performance computing (HPC) platforms and faster algorithms have resulted in the work of Dutta et al. [2016], where Lagrangian particle tracking was coupled with high-resolution Large Eddy Simulations (LES) to model the complex and highly non-linear phenomenon of Bulle-Effect at diversions. Despite all the advancements in using Lagrangian particle tracking, there has not been a study that looks in detail at the limits of the model in the context of sediment transport, and also analyzes the sensitivity of the various force formulation in the force balance equation of the particles. Niño and Garcia [1994] did a similar analysis, but the vertical flow velocity distribution was modeled as the log-law. The current study extends the analysis by modeling the flow using high-resolution LES at a Reynolds number comparable to experiments of Niño et al. [1994]. Dutta et al., (2016), Large Eddy Simulation (LES) of flow and bedload transport at an idealized 90-degree diversion: insight into Bulle-Effect, River Flow 2016 - Constantinescu, Garcia & Hanes (Eds), Taylor & Francis Group, London, 101-109. Escauriaza and Sotiropoulos

Particle-wall tribology of slippery hydrogel particle suspensions.

PubMed

Shewan, Heather M; Stokes, Jason R; Cloitre, Michel

2017-03-08

Slip is an important phenomenon that occurs during the flow of yield stress fluids like soft materials and pastes. Densely packed suspensions of hydrogel microparticles are used to show that slip is governed by the tribological interactions occurring between the samples and shearing surfaces. Both attractive/repulsive interactions between the dispersed particles and surface, as well as the viscoelasticity of the suspension, are found to play key roles in slip occurring within rheometric flows. We specifically discover that for two completely different sets of microgels, the sliding stress at which slip occurs scales with both the modulus of the particles and the bulk suspension modulus. This suggests that hysteresis losses within the viscoelastic particles contribute to friction forces and thus slip at the particle-surface tribo-contact. It is also found that slip during large amplitude oscillatory shear and steady shear flows share the same generic features.

Performance of a large size triple GEM detector at high particle rate for the CBM Experiment at FAIR

NASA Astrophysics Data System (ADS)

Adak, Rama Prasad; Kumar, Ajit; Dubey, Anand Kumar; Chattopadhyay, Subhasis; Das, Supriya; Raha, Sibaji; Samanta, Subhasis; Saini, Jogender

2017-02-01

In CBM Experiment at FAIR, dimuons will be detected by a Muon Chamber (MUCH) consisting of segmented absorbers of varying widths and tracking chambers sandwiched between the absorber-pairs. In this fixed target heavy-ion collision experiment, operating at highest interaction rate of 10 MHz for Au+Au collision, the inner region of the 1st detector will face a particle rate of 1 MHz/cm2. To operate at such a high particle density, GEM technology based detectors have been selected for the first two stations of MUCH. We have reported earlier the performance of several small-size GEM detector prototypes built at VECC for use in MUCH. In this work, we report on a large GEM prototype tested with proton beam of momentum 2.36 GeV/c at COSY-Jülich Germany. The detector was read out using nXYTER operated in self-triggering mode. An efficiency higher than 96% at ΔVGEM = 375.2 V was achieved. The variation of efficiency with the rate of incoming protons has been found to vary within 2% when tested up to a maximum rate of 2.8 MHz/cm2. The gain was found to be stable at high particle rate with a maximum variation of ∼9%.

Viscosity of particle laden films

NASA Astrophysics Data System (ADS)

Timounay, Yousra; Rouyer, Florence

2017-06-01

We perform retraction experiments on soap films where large particles bridge the two interfaces. Local velocities are measured by PIV during the unstationnary regime. The velocity variation in time and space can be described by a continuous fluid model from which effective viscosity (shear and dilatational) of particulate films is measured. The 2D effective viscosity of particulate films η2D increases with particle surface fraction ϕ: at low ϕ, it tends to the interfacial dilatational viscosity of the liquid/air interfaces and it diverges at the critical particle surface fraction ϕc ≃ 0.84. Experimental data agree with classical viscosity laws of hard spheres suspensions adapted to the 2D geometry, assuming viscous dissipation resulting from the squeeze of the liquid/air interfaces between the particles. Finally, we show that the observed viscous dissipation in particulate films has to be considered to describe the edge velocity during a retraction experiment at large particle coverage.

Scalable Domain Decomposed Monte Carlo Particle Transport

NASA Astrophysics Data System (ADS)

O'Brien, Matthew Joseph

In this dissertation, we present the parallel algorithms necessary to run domain decomposed Monte Carlo particle transport on large numbers of processors (millions of processors). Previous algorithms were not scalable, and the parallel overhead became more computationally costly than the numerical simulation. The main algorithms we consider are: • Domain decomposition of constructive solid geometry: enables extremely large calculations in which the background geometry is too large to fit in the memory of a single computational node. • Load Balancing: keeps the workload per processor as even as possible so the calculation runs efficiently. • Global Particle Find: if particles are on the wrong processor, globally resolve their locations to the correct processor based on particle coordinate and background domain. • Visualizing constructive solid geometry, sourcing particles, deciding that particle streaming communication is completed and spatial redecomposition. These algorithms are some of the most important parallel algorithms required for domain decomposed Monte Carlo particle transport. We demonstrate that our previous algorithms were not scalable, prove that our new algorithms are scalable, and run some of the algorithms up to 2 million MPI processes on the Sequoia supercomputer.

Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope.

PubMed

Ajello, M; Albert, A; Anderson, B; Baldini, L; Barbiellini, G; Bastieri, D; Bellazzini, R; Bissaldi, E; Blandford, R D; Bloom, E D; Bonino, R; Bottacini, E; Bregeon, J; Bruel, P; Buehler, R; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cecchi, C; Chekhtman, A; Ciprini, S; Cohen-Tanugi, J; Conrad, J; Costanza, F; D'Ammando, F; de Angelis, A; de Palma, F; Desiante, R; Di Mauro, M; Di Venere, L; Domínguez, A; Drell, P S; Favuzzi, C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Giglietto, N; Glanzman, T; Godfrey, G; Guiriec, S; Horan, D; Jóhannesson, G; Katsuragawa, M; Kensei, S; Kuss, M; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Maldera, S; Manfreda, A; Mayer, M; Mazziotta, M N; Meyer, M; Michelson, P F; Mirabal, N; Mizuno, T; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Negro, M; Nuss, E; Okada, C; Orlando, E; Ormes, J F; Paneque, D; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Sánchez-Conde, M; Sgrò, C; Simone, D; Siskind, E J; Spada, F; Spandre, G; Spinelli, P; Takahashi, H; Thayer, J B; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Wood, K S; Wood, M; Zaharijas, G; Zimmer, S

2016-04-22

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12}  GeV^{-1} for ALP masses 0.5≲m_{a}≲5  neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

Designing a systematic landscape monitoring approach for quantifying ecosystem services

EPA Science Inventory

A key problem encountered early on by governments striving to incorporate the ecosystem services concept into decision making is quantifying ecosystem services across large landscapes. Basically, they are faced with determining what to measure, how to measure it and how to aggre...

Ultrafine particle transport and deposition in a large scale 17-generation lung model.

PubMed

Islam, Mohammad S; Saha, Suvash C; Sauret, Emilie; Gemci, Tevfik; Yang, Ian A; Gu, Y T

2017-11-07

To understand how to assess optimally the risks of inhaled particles on respiratory health, it is necessary to comprehend the uptake of ultrafine particulate matter by inhalation during the complex transport process through a non-dichotomously bifurcating network of conduit airways. It is evident that the highly toxic ultrafine particles damage the respiratory epithelium in the terminal bronchioles. The wide range of in silico available and the limited realistic model for the extrathoracic region of the lung have improved understanding of the ultrafine particle transport and deposition (TD) in the upper airways. However, comprehensive ultrafine particle TD data for the real and entire lung model are still unavailable in the literature. Therefore, this study is aimed to provide an understanding of the ultrafine particle TD in the terminal bronchioles for the development of future therapeutics. The Euler-Lagrange (E-L) approach and ANSYS fluent (17.2) solver were used to investigate ultrafine particle TD. The physical conditions of sleeping, resting, and light activity were considered in this modelling study. A comprehensive pressure-drop along five selected path lines in different lobes was calculated. The non-linear behaviour of pressure-drops is observed, which could aid the health risk assessment system for patients with respiratory diseases. Numerical results also showed that ultrafine particle-deposition efficiency (DE) in different lobes is different for various physical activities. Moreover, the numerical results showed hot spots in various locations among the different lobes for different flow rates, which could be helpful for targeted therapeutical aerosol transport to terminal bronchioles and the alveolar region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pairwise Interaction Extended Point-Particle (PIEP) model for multiphase jets and sedimenting particles

NASA Astrophysics Data System (ADS)

Liu, Kai; Balachandar, S.

2017-11-01

We perform a series of Euler-Lagrange direct numerical simulations (DNS) for multiphase jets and sedimenting particles. The forces the flow exerts on the particles in these two-way coupled simulations are computed using the Basset-Bousinesq-Oseen (BBO) equations. These forces do not explicitly account for particle-particle interactions, even though such pairwise interactions induced by the perturbations from neighboring particles may be important especially when the particle volume fraction is high. Such effects have been largely unaddressed in the literature. Here, we implement the Pairwise Interaction Extended Point-Particle (PIEP) model to simulate the effect of neighboring particle pairs. A simple collision model is also applied to avoid unphysical overlapping of solid spherical particles. The simulation results indicate that the PIEP model provides a more elaborative and complicated movement of the dispersed phase (droplets and particles). Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) project N00014-16-1-2617.

Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

NASA Astrophysics Data System (ADS)

Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de; Chen, Kang

2015-12-01

The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here, we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large self-propelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of the chains were observed for low and high grafting densities. Surprisingly, we find a weak descent of the average end-to-end distance of chains at high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath.

Numerical investigation of compaction of deformable particles with bonded-particle model

NASA Astrophysics Data System (ADS)

Dosta, Maksym; Costa, Clara; Al-Qureshi, Hazim

2017-06-01

In this contribution, a novel approach developed for the microscale modelling of particles which undergo large deformations is presented. The proposed method is based on the bonded-particle model (BPM) and multi-stage strategy to adjust material and model parameters. By the BPM, modelled objects are represented as agglomerates which consist of smaller ideally spherical particles and are connected with cylindrical solid bonds. Each bond is considered as a separate object and in each time step the forces and moments acting in them are calculated. The developed approach has been applied to simulate the compaction of elastomeric rubber particles as single particles or in a random packing. To describe the complex mechanical behaviour of the particles, the solid bonds were modelled as ideally elastic beams. The functional parameters of solid bonds as well as material parameters of bonds and primary particles were estimated based on the experimental data for rubber spheres. Obtained results for acting force and for particle deformations during uniaxial compression are in good agreement with experimental data at higher strains.

Quantifying resilience

USGS Publications Warehouse

Allen, Craig R.; Angeler, David G.

2016-01-01

Several frameworks to operationalize resilience have been proposed. A decade ago, a special feature focused on quantifying resilience was published in the journal Ecosystems (Carpenter, Westley & Turner 2005). The approach there was towards identifying surrogates of resilience, but few of the papers proposed quantifiable metrics. Consequently, many ecological resilience frameworks remain vague and difficult to quantify, a problem that this special feature aims to address. However, considerable progress has been made during the last decade (e.g. Pope, Allen & Angeler 2014). Although some argue that resilience is best kept as an unquantifiable, vague concept (Quinlan et al. 2016), to be useful for managers, there must be concrete guidance regarding how and what to manage and how to measure success (Garmestani, Allen & Benson 2013; Spears et al. 2015). Ideas such as ‘resilience thinking’ have utility in helping stakeholders conceptualize their systems, but provide little guidance on how to make resilience useful for ecosystem management, other than suggesting an ambiguous, Goldilocks approach of being just right (e.g. diverse, but not too diverse; connected, but not too connected). Here, we clarify some prominent resilience terms and concepts, introduce and synthesize the papers in this special feature on quantifying resilience and identify core unanswered questions related to resilience.

Deterministic particle transport in a ratchet flow.

PubMed

Beltrame, Philippe; Makhoul, Mounia; Joelson, Maminirina

2016-01-01

This study is motivated by the issue of the pumping of particle through a periodic modulated channel. We focus on a simplified deterministic model of small inertia particles within the Stokes flow framework that we call "ratchet flow." A path-following method is employed in the parameter space in order to retrace the scenario which from bounded periodic solutions leads to particle transport. Depending on whether the magnitude of the particle drag is moderate or large, two main transport mechanisms are identified in which the role of the parity symmetry of the flow differs. For large drag, transport is induced by flow asymmetry, while for moderate drag, since the full transport solution bifurcation structure already exists for symmetric settings, flow asymmetry only makes the transport effective. We analyzed the scenarios of current reversals for each mechanism as well as the role of synchronization. In particular we show that, for large drag, the particle drift is similar to phase slip in a synchronization problem.

A Charged Particle Veto Wall for the Large Area Neutron Array (LANA)

NASA Astrophysics Data System (ADS)

Zhu, K.; Chajecki, Z.; Anderson, C.; Bromell, J.; Brown, K.; Crosby, J.; Kodali, S.; Lynch, W. G.; Morfouace, P.; Sweany, S.; Tsang, M. B.; Tsang, C.; Brett, J. J.; Swaim, J. L.

2017-09-01

Comparison of neutrons and protons emitted in heavy ion collisions is one of the observables to probe symmetry energy, which is related to the properties of neutron star. In general, neutrons are difficult to measure and neutron detectors are not as easy to use or as widely available as charged particle detectors. Two neutron walls (NW) called LANA exist at the National Superconducting Cyclotron Laboratory. Although the NSCL NW attains excellent discrimination of γ rays and neutron, it fails to discriminate charged particles from neutrons. To ensure near 100% rejection of charged particles, a Charged Particle Veto Wall (VW) is being jointly built by Michigan State University and Western Michigan University. It will be placed in front of one NW. To increase efficiency in detecting neutrons, the second neutron wall is stacked behind it. In this presentation, I will discuss the design, construction and testing of the VW together with the LANA in preparation of two approved NSCL experiments to probe the density and momentum dependence of the symmetry energy potentials in the equation state of the asymmetric nuclear matter. This material is based upon work supported by the National Science Foundation under Grant No. PHY 1565546.

Microstructural evolution during sintering of copper particles studied by laboratory diffraction contrast tomography (LabDCT).

PubMed

McDonald, S A; Holzner, C; Lauridsen, E M; Reischig, P; Merkle, A P; Withers, P J

2017-07-12

Pressureless sintering of loose or compacted granular bodies at elevated temperature occurs by a combination of particle rearrangement, rotation, local deformation and diffusion, and grain growth. Understanding of how each of these processes contributes to the densification of a powder body is still immature. Here we report a fundamental study coupling the crystallographic imaging capability of laboratory diffraction contrast tomography (LabDCT) with conventional computed tomography (CT) in a time-lapse study. We are able to follow and differentiate these processes non-destructively and in three-dimensions during the sintering of a simple copper powder sample at 1050 °C. LabDCT quantifies particle rotation (to <0.05° accuracy) and grain growth while absorption CT simultaneously records the diffusion and deformation-related morphological changes of the sintering particles. We find that the rate of particle rotation is lowest for the more highly coordinated particles and decreases during sintering. Consequently, rotations are greater for surface breaking particles than for more highly coordinated interior ones. Both rolling (cooperative) and sliding particle rotations are observed. By tracking individual grains the grain growth/shrinkage kinetics during sintering are quantified grain by grain for the first time. Rapid, abnormal grain growth is observed for one grain while others either grow or are consumed more gradually.

Investigating the size, shape and surface roughness dependence of polarization lidars with light-scattering computations on real mineral dust particles: Application to dust particles' external mixtures and dust mass concentration retrievals

NASA Astrophysics Data System (ADS)

Mehri, Tahar; Kemppinen, Osku; David, Grégory; Lindqvist, Hannakaisa; Tyynelä, Jani; Nousiainen, Timo; Rairoux, Patrick; Miffre, Alain

2018-05-01

Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass concentrations, polarization lidars are nowadays frequently used, with partitioning algorithms allowing to discern the contribution of mineral dust in two or three-component particle external mixtures. In this paper, we investigate the dependence of the retrieved dust backscattering (βd) vertical profiles with the dust particle size and shape. For that, new light-scattering numerical simulations are performed on real atmospheric mineral dust particles, having determined mineralogy (CAL, DOL, AGG, SIL), derived from stereogrammetry (stereo-particles), with potential surface roughness, which are compared to the widely-used spheroidal mathematical shape model. For each dust shape model (smooth stereo-particles, rough stereo-particles, spheroids), the dust depolarization, backscattering Ångström exponent, lidar ratio are computed for two size distributions representative of mineral dust after long-range transport. As an output, two Saharan dust outbreaks involving mineral dust in two, then three-component particle mixtures are studied with Lyon (France) UV-VIS polarization lidar. If the dust size matters most, under certain circumstances, βd can vary by approximately 67% when real dust stereo-particles are used instead of spheroids, corresponding to variations in the dust backscattering coefficient as large as 2 Mm- 1·sr- 1. Moreover, the influence of surface roughness in polarization lidar retrievals is for the first time discussed. Finally, dust mass-extinction conversion factors (ηd) are evaluated for each assigned shape model and dust mass concentrations are retrieved from polarization lidar measurements. From

Weekly variation of atmospheric particle micromorphology and chemistry in Brussels urban environment.

PubMed

Zaady, Eli; Carati, D; Brenig, L; Vanderstraeten, P; Lénelle, Y; Meurrens, A; Offer, Z Y

2010-10-01

The purpose of this study was to measure the impact of urban activities on airborne particle dynamics during weekend periods in Brussels urban area. Differences in the granulometry and micromorphology between particles sampled on working days and weekends were studied. We quantified the area, size, number, and the chemistry parameters of the airborne particles and compared between Saturday, Sunday, and Monday. We report and analyze data on airborne particles up to PM10, measured in the Brussels region from October 2002 to September 2003. Our investigation reveals detailed information regarding chemical composition of the airborne particles over the weekend period in the Brussels urban area. Furthermore, the majority of the airborne particles in the Brussels region may belong to sources geographically outside the (in situ) Brussels area.

Uncertainty quantification in Eulerian-Lagrangian models for particle-laden flows

NASA Astrophysics Data System (ADS)

Fountoulakis, Vasileios; Jacobs, Gustaaf; Udaykumar, Hs

2017-11-01

A common approach to ameliorate the computational burden in simulations of particle-laden flows is to use a point-particle based Eulerian-Lagrangian model, which traces individual particles in their Lagrangian frame and models particles as mathematical points. The particle motion is determined by Stokes drag law, which is empirically corrected for Reynolds number, Mach number and other parameters. The empirical corrections are subject to uncertainty. Treating them as random variables renders the coupled system of PDEs and ODEs stochastic. An approach to quantify the propagation of this parametric uncertainty to the particle solution variables is proposed. The approach is based on averaging of the governing equations and allows for estimation of the first moments of the quantities of interest. We demonstrate the feasibility of our proposed methodology of uncertainty quantification of particle-laden flows on one-dimensional linear and nonlinear Eulerian-Lagrangian systems. This research is supported by AFOSR under Grant FA9550-16-1-0008.

Quantifying Auditory Temporal Stability in a Large Database of Recorded Music

PubMed Central

Ellis, Robert J.; Duan, Zhiyan; Wang, Ye

2014-01-01

“Moving to the beat” is both one of the most basic and one of the most profound means by which humans (and a few other species) interact with music. Computer algorithms that detect the precise temporal location of beats (i.e., pulses of musical “energy”) in recorded music have important practical applications, such as the creation of playlists with a particular tempo for rehabilitation (e.g., rhythmic gait training), exercise (e.g., jogging), or entertainment (e.g., continuous dance mixes). Although several such algorithms return simple point estimates of an audio file’s temporal structure (e.g., “average tempo”, “time signature”), none has sought to quantify the temporal stability of a series of detected beats. Such a method-a “Balanced Evaluation of Auditory Temporal Stability” (BEATS)–is proposed here, and is illustrated using the Million Song Dataset (a collection of audio features and music metadata for nearly one million audio files). A publically accessible web interface is also presented, which combines the thresholdable statistics of BEATS with queryable metadata terms, fostering potential avenues of research and facilitating the creation of highly personalized music playlists for clinical or recreational applications. PMID:25469636

Quantifying auditory temporal stability in a large database of recorded music.

PubMed

Ellis, Robert J; Duan, Zhiyan; Wang, Ye

2014-01-01

"Moving to the beat" is both one of the most basic and one of the most profound means by which humans (and a few other species) interact with music. Computer algorithms that detect the precise temporal location of beats (i.e., pulses of musical "energy") in recorded music have important practical applications, such as the creation of playlists with a particular tempo for rehabilitation (e.g., rhythmic gait training), exercise (e.g., jogging), or entertainment (e.g., continuous dance mixes). Although several such algorithms return simple point estimates of an audio file's temporal structure (e.g., "average tempo", "time signature"), none has sought to quantify the temporal stability of a series of detected beats. Such a method--a "Balanced Evaluation of Auditory Temporal Stability" (BEATS)--is proposed here, and is illustrated using the Million Song Dataset (a collection of audio features and music metadata for nearly one million audio files). A publically accessible web interface is also presented, which combines the thresholdable statistics of BEATS with queryable metadata terms, fostering potential avenues of research and facilitating the creation of highly personalized music playlists for clinical or recreational applications.

The rotation and translation of non-spherical particles in homogeneous isotropic turbulence

NASA Astrophysics Data System (ADS)

Byron, Margaret

The motion of particles suspended in environmental turbulence is relevant to many scientific fields, from sediment transport to biological interactions to underwater robotics. At very small scales and simple shapes, we are able to completely mathematically describe the motion of inertial particles; however, the motion of large aspherical particles is significantly more complex, and current computational models are inadequate for large or highly-resolved domains. Therefore, we seek to experimentally investigate the coupling between freely suspended particles and ambient turbulence. A better understanding of this coupling will inform not only engineering and physics, but the interactions between small aquatic organisms and their environments. In the following pages, we explore the roles of shape and buoyancy on the motion of passive particles in turbulence, and allow these particles to serve as models for meso-scale aquatic organisms. We fabricate cylindrical and spheroidal particles and suspend them in homogeneous, isotropic turbulence that is generated via randomly-actuated jet arrays. The particles are fabricated with agarose hydrogel, which is refractive-index-matched to the surrounding fluid (water). Both the fluid and the particle are seeded with passive tracers, allowing us to perform Particle Image Velocimetry (PIV) simultaneously on the particle and fluid phase. To investigate the effects of shape, particles are fabricated at varying aspect ratios; to investigate the effects of buoyancy, particles are fabricated at varying specific gravities. Each particle type is freely suspended at a volume fraction of F=0.1%, for which four-way coupling interactions are negligible. The suspended particles are imaged together with the surrounding fluid and analyzed using stereoscopic PIV, which yields three velocity components in a two-dimensional measurement plane. Using image thresholding, the results are separated into simultaneous fluid-phase and solid-phase velocity

Crack Initiation and Growth Behavior of Cold-Sprayed Ni Particles on IN718 Alloy

NASA Astrophysics Data System (ADS)

Cavaliere, P.; Silvello, A.

2017-04-01

Cold spray processing parameters, governing particle velocity and impact energy, are analyzed in the present paper for pure Ni sprayed on IN718 substrates. Finite element modeling (FEM) was used to calculate the particle impact velocity and temperature as a function of gas temperature and pressure and particle density and dimensions. Experimental evidence underlines the possibility of performing repairing through cold spray thanks to the good level of adhesion achievable by employing optimal combinations of materials and spray processing parameters. In the present paper, the potential repairing of cracked superalloys sheets, by employing cold spray technology, is presented. 30° surface V-notched IN718 panels have been repaired by using pure Ni cold-sprayed powders. The bending behavior of the repaired sheets was analyzed by FEM and mechanical testing in order to compare the properties with those belonging to the unrepaired panels. Simulations and mechanical results showed a reduction in the stress intensity factor, a modification of the crack initiation site and a crack retardation in the repaired structures if compared with the unrepaired ones. The K factor was quantified; the resistance of repaired panels was increased of more than eight times in the case of repairing with Ni cold spray particles. Geometrical and mechanical properties of the coating-substrate interfaces, such as adhesion strength and residual stresses influencing the coatings behavior, were largely analyzed.

High-Throughput Particle Uptake Analysis by Imaging Flow Cytometry

PubMed Central

Smirnov, Asya; Solga, Michael D.; Lannigan, Joanne; Criss, Alison K.

2017-01-01

Quantifying the efficiency of particle uptake by host cells is important in fields including infectious diseases, autoimmunity, cancer, developmental biology, and drug delivery. Here we present a protocol for high-throughput analysis of particle uptake using imaging flow cytometry, using the bacterium Neisseria gonorrhoeae attached and internalized to neutrophils as an example. Cells are exposed to fluorescently labeled bacteria, fixed, and stained with a bacteria-specific antibody of a different fluorophore. Thus in the absence of a permeabilizing agent, extracellular bacteria are double-labeled with two fluorophores while intracellular bacteria remain single-labeled. A spot count algorithm is used to determine the number of single- and double-labeled bacteria in individual cells, to calculate the percent of cells associated with bacteria, percent of cells with internalized bacteria, and percent of cell-associated bacteria that are internalized. These analyses quantify bacterial association and internalization across thousands of cells and can be applied to diverse experimental systems. PMID:28369762

Particle interaction of lubricated or unlubricated binary mixtures according to their particle size and densification mechanism.

PubMed

Di Martino, Piera; Joiris, Etienne; Martelli, Sante

2004-09-01

The aim of this study is to assess an experimental approach for technological development of a direct compression formulation. A simple formula was considered composed by an active ingredient, a diluent and a lubricant. The active ingredient and diluent were selected as an example according to their typical densification mechanism: the nitrofurantoine, a fragmenting material, and the cellulose microcrystalline (Vivapur), which is a typical visco-elastic material, equally displaying good bind and disintegrant properties. For each ingredient, samples of different particle size distribution were selected. Initially, tabletability of pure materials was studied by a rotary press without magnesium stearate. Vivapur tabletability decreases with increase in particle size. The addition of magnesium stearate as lubricant decreases tabletability of Vivapur of greater particle size, while it kept unmodified that of Vivapur of lower particle size. Differences in tabletability can be related to differences in particle-particle interactions; for Vivapur of higher particle size (Vivapur 200, 102 and 101), the lower surface area develops lower surface available for bonds, while for Vivapur of lower particle size (99 and 105) the greater surface area allows high particle proximity favouring particle cohesivity. Nitrofurantoine shows great differences in compression behaviour according to its particle size distribution. Large crystals show poorer tabletability than fine crystals, further decreased by lubricant addition. The large crystals poor tabletability is due to their poor compactibility, in spite of high compressibility and plastic intrinsic deformability; in fact, in spite of the high densification tendency, the nature of the involved bonds is very weak. Nitrofurantoine samples were then mixed with Vivapurs in different proportions. Compression behaviour of binary mixes (tabletability and compressibility) was then evaluated according to diluents proportion in the mixes. The

Parallel Large-Scale Molecular Dynamics Simulation Opens New Perspective to Clarify the Effect of a Porous Structure on the Sintering Process of Ni/YSZ Multiparticles.

PubMed

Xu, Jingxiang; Higuchi, Yuji; Ozawa, Nobuki; Sato, Kazuhisa; Hashida, Toshiyuki; Kubo, Momoji

2017-09-20

Ni sintering in the Ni/YSZ porous anode of a solid oxide fuel cell changes the porous structure, leading to degradation. Preventing sintering and degradation during operation is a great challenge. Usually, a sintering molecular dynamics (MD) simulation model consisting of two particles on a substrate is used; however, the model cannot reflect the porous structure effect on sintering. In our previous study, a multi-nanoparticle sintering modeling method with tens of thousands of atoms revealed the effect of the particle framework and porosity on sintering. However, the method cannot reveal the effect of the particle size on sintering and the effect of sintering on the change in the porous structure. In the present study, we report a strategy to reveal them in the porous structure by using our multi-nanoparticle modeling method and a parallel large-scale multimillion-atom MD simulator. We used this method to investigate the effect of YSZ particle size and tortuosity on sintering and degradation in the Ni/YSZ anodes. Our parallel large-scale MD simulation showed that the sintering degree decreased as the YSZ particle size decreased. The gas fuel diffusion path, which reflects the overpotential, was blocked by pore coalescence during sintering. The degradation of gas diffusion performance increased as the YSZ particle size increased. Furthermore, the gas diffusion performance was quantified by a tortuosity parameter and an optimal YSZ particle size, which is equal to that of Ni, was found for good diffusion after sintering. These findings cannot be obtained by previous MD sintering studies with tens of thousands of atoms. The present parallel large-scale multimillion-atom MD simulation makes it possible to clarify the effects of the particle size and tortuosity on sintering and degradation.

Particle Swarm Optimization

NASA Technical Reports Server (NTRS)

Venter, Gerhard; Sobieszczanski-Sobieski Jaroslaw

2002-01-01

The purpose of this paper is to show how the search algorithm known as particle swarm optimization performs. Here, particle swarm optimization is applied to structural design problems, but the method has a much wider range of possible applications. The paper's new contributions are improvements to the particle swarm optimization algorithm and conclusions and recommendations as to the utility of the algorithm, Results of numerical experiments for both continuous and discrete applications are presented in the paper. The results indicate that the particle swarm optimization algorithm does locate the constrained minimum design in continuous applications with very good precision, albeit at a much higher computational cost than that of a typical gradient based optimizer. However, the true potential of particle swarm optimization is primarily in applications with discrete and/or discontinuous functions and variables. Additionally, particle swarm optimization has the potential of efficient computation with very large numbers of concurrently operating processors.

Compaction of granular materials composed of deformable particles

NASA Astrophysics Data System (ADS)

Nguyen, Thanh Hai; Nezamabadi, Saeid; Delenne, Jean-Yves; Radjai, Farhang

2017-06-01

In soft particle materials such as metallic powders the particles can undergo large deformations without rupture. The large elastic or plastic deformations of the particles are expected to strongly affect the mechanical properties of these materials compared to hard particle materials more often considered in research on granular materials. Herein, two numerical approaches are proposed for the simulation of soft granular systems: (i) an implicit formulation of the Material Point Method (MPM) combined with the Contact Dynamics (CD) method to deal with contact interactions, and (i) Bonded Particle Model (BPM), in which each deformable particle is modeled as an aggregate of rigid primary particles using the CD method. These two approaches allow us to simulate the compaction of an assembly of elastic or plastic particles. By analyzing the uniaxial compaction of 2D soft particle packings, we investigate the effects of particle shape change on the stress-strain relationship and volume change behavior as well as the evolution of the microstructure.

The accurate particle tracer code

NASA Astrophysics Data System (ADS)

Wang, Yulei; Liu, Jian; Qin, Hong; Yu, Zhi; Yao, Yicun

2017-11-01

The Accurate Particle Tracer (APT) code is designed for systematic large-scale applications of geometric algorithms for particle dynamical simulations. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and nonlinear problems. To provide a flexible and convenient I/O interface, the libraries of Lua and Hdf5 are used. Following a three-step procedure, users can efficiently extend the libraries of electromagnetic configurations, external non-electromagnetic forces, particle pushers, and initialization approaches by use of the extendible module. APT has been used in simulations of key physical problems, such as runaway electrons in tokamaks and energetic particles in Van Allen belt. As an important realization, the APT-SW version has been successfully distributed on the world's fastest computer, the Sunway TaihuLight supercomputer, by supporting master-slave architecture of Sunway many-core processors. Based on large-scale simulations of a runaway beam under parameters of the ITER tokamak, it is revealed that the magnetic ripple field can disperse the pitch-angle distribution significantly and improve the confinement of energetic runaway beam on the same time.

The accurate particle tracer code

DOE PAGES

Wang, Yulei; Liu, Jian; Qin, Hong; ...

2017-07-20

The Accurate Particle Tracer (APT) code is designed for systematic large-scale applications of geometric algorithms for particle dynamical simulations. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and nonlinear problems. To provide a flexible and convenient I/O interface, the libraries of Lua and Hdf5 are used. Following a three-step procedure, users can efficiently extend the libraries of electromagnetic configurations, external non-electromagnetic forces, particle pushers, and initialization approaches by use of the extendible module. APT has been used in simulations of key physical problems, such as runawaymore » electrons in tokamaks and energetic particles in Van Allen belt. As an important realization, the APT-SW version has been successfully distributed on the world’s fastest computer, the Sunway TaihuLight supercomputer, by supporting master–slave architecture of Sunway many-core processors. Here, based on large-scale simulations of a runaway beam under parameters of the ITER tokamak, it is revealed that the magnetic ripple field can disperse the pitch-angle distribution significantly and improve the confinement of energetic runaway beam on the same time.« less

The accurate particle tracer code

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

Wang, Yulei; Liu, Jian; Qin, Hong

The Accurate Particle Tracer (APT) code is designed for systematic large-scale applications of geometric algorithms for particle dynamical simulations. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and nonlinear problems. To provide a flexible and convenient I/O interface, the libraries of Lua and Hdf5 are used. Following a three-step procedure, users can efficiently extend the libraries of electromagnetic configurations, external non-electromagnetic forces, particle pushers, and initialization approaches by use of the extendible module. APT has been used in simulations of key physical problems, such as runawaymore » electrons in tokamaks and energetic particles in Van Allen belt. As an important realization, the APT-SW version has been successfully distributed on the world’s fastest computer, the Sunway TaihuLight supercomputer, by supporting master–slave architecture of Sunway many-core processors. Here, based on large-scale simulations of a runaway beam under parameters of the ITER tokamak, it is revealed that the magnetic ripple field can disperse the pitch-angle distribution significantly and improve the confinement of energetic runaway beam on the same time.« less

The characterisation of diesel exhaust particles - composition, size distribution and partitioning.

PubMed

Alam, Mohammed S; Zeraati-Rezaei, Soheil; Stark, Christopher P; Liang, Zhirong; Xu, Hongming; Harrison, Roy M

2016-07-18

A number of major research questions remain concerning the sources and properties of road traffic generated particulate matter. A full understanding of the composition of primary vehicle exhaust aerosol and its contribution to secondary organic aerosol (SOA) formation still remains elusive, and many uncertainties exist relating to the semi-volatile component of the particles. Semi-Volatile Organic Compounds (SVOCs) are compounds which partition directly between the gas and aerosol phases under ambient conditions. The SVOCs in engine exhaust are typically hydrocarbons in the C15-C35 range, and are largely uncharacterised because they are unresolved by traditional gas chromatography, forming a large hump in the chromatogram referred to as Unresolved Complex Mixture (UCM). In this study, thermal desorption coupled to comprehensive Two Dimensional Gas-Chromatography Time-of-Flight Mass-Spectrometry (TD-GC × GC-ToF-MS) was exploited to characterise and quantify the composition of SVOCs from the exhaust emission. Samples were collected from the exhaust of a diesel engine, sampling before and after a diesel oxidation catalyst (DOC), while testing at steady state conditions. Engine exhaust was diluted with air and collected using both filter and impaction (nano-MOUDI), to resolve total mass and size resolved mass respectively. Adsorption tubes were utilised to collect SVOCs in the gas phase and they were then analysed using thermal desorption, while particle size distribution was evaluated by sampling with a DMS500. The SVOCs were observed to contain predominantly n-alkanes, branched alkanes, alkyl-cycloalkanes, alkyl-benzenes, PAHs and various cyclic aromatics. Particle phase compounds identified were similar to those observed in engine lubricants, while vapour phase constituents were similar to those measured in fuels. Preliminary results are presented illustrating differences in the particle size distribution and SVOCs composition when collecting samples with and

Interactive Terascale Particle Visualization

NASA Technical Reports Server (NTRS)

Ellsworth, David; Green, Bryan; Moran, Patrick

2004-01-01

This paper describes the methods used to produce an interactive visualization of a 2 TB computational fluid dynamics (CFD) data set using particle tracing (streaklines). We use the method introduced by Bruckschen et al. [2001] that pre-computes a large number of particles, stores them on disk using a space-filling curve ordering that minimizes seeks, and then retrieves and displays the particles according to the user's command. We describe how the particle computation can be performed using a PC cluster, how the algorithm can be adapted to work with a multi-block curvilinear mesh, and how the out-of-core visualization can be scaled to 296 billion particles while still achieving interactive performance on PG hardware. Compared to the earlier work, our data set size and total number of particles are an order of magnitude larger. We also describe a new compression technique that allows the lossless compression of the particles by 41% and speeds the particle retrieval by about 30%.

Quantifying uncertainties in precipitation measurement

NASA Astrophysics Data System (ADS)

Chen, H. Z. D.

2017-12-01

The scientific community have a long history of utilizing precipitation data for climate model design. However, precipitation record and its model contains more uncertainty than its temperature counterpart. Literature research have shown precipitation measurements to be highly influenced by its surrounding environment, and weather stations are traditionally situated in open areas and subject to various limitations. As a result, this restriction limits the ability of the scientific community to fully close the loop on the water cycle. Horizontal redistribution have been shown to be a major factor influencing precipitation measurements. Efforts have been placed on reducing its effect on the monitoring apparatus. However, the amount of factors contributing to this uncertainty is numerous and difficult to fully capture. As a result, noise factor remains high in precipitation data. This study aims to quantify all uncertainties in precipitation data by factoring out horizontal redistribution by measuring them directly. Horizontal contribution of precipitation will be quantified by measuring precipitation at different heights, with one directly shadowing the other. The above collection represents traditional precipitation data, whereas the bottom measurements sums up the overall error term at given location. Measurements will be recorded and correlated with nearest available wind measurements to quantify its impact on traditional precipitation record. Collections at different locations will also be compared to see whether this phenomenon is location specific or if a general trend can be derived. We aim to demonstrate a new way to isolate the noise component in traditional precipitation data via empirical measurements. By doing so, improve the overall quality of historic precipitation record. As a result, provide a more accurate information for the design and calibration of large scale climate modeling.

Aging of black carbon particles under polluted urban environments: timescale, hygroscopicity and enhanced absorption and direct radiative forcing

NASA Astrophysics Data System (ADS)

Peng, J.; Hu, M.; Guo, S.; Du, Z.; Zheng, J.; Shang, D.; Levy Zamora, M.; Shao, M.; Wu, Y.; Zheng, J.; Wang, Y.; Zeng, L.; Collins, D. R.; Molina, M.; Zhang, R.

2017-12-01

Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the hygroscopic and optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using an outdoor environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. The κ (kappa) values of coating materials are calculated as 0.04 at both subsaturation and supersaturation conditions, respectively, indicating that the initial photochemical aging of BC particles does not appreciably alter the BC hygroscopicity. Our findings suggest that BC aging under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope

DOE PAGES

Ajello, M.; Albert, A.; Anderson, B.; ...

2016-04-20

In this paper, we report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5 x 10 -12 GeV -1 for ALP masses 0.5 ≲ m a ≲ 5 neV at 95% confidence. Finally, the limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity ofmore » the Universe.« less

Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ajello, M.; Albert, A.; Anderson, B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R.D.; Mirabal, N.;

Computer simulation of the classical entanglement of U-shaped particles in three dimensions

NASA Astrophysics Data System (ADS)

Maddock, Brian; Lindner, John

2014-03-01

Classical entanglement is important in a wide range of phenomena, such as velcro hook-and-loop-fasteners, seed dispersal by animal fur, and bent liquid crystal molecules. We present a computer simulation of the entanglement of U-shaped particles in three dimensions. We represent the particles by phenomenological potentials and evolve them by integrating Newton's laws of motion. We drop them into a virtual cylinder, shake them, and ultimately release the cylinder. As the particle piles relax, we quantify their entanglement by the exponential decay times of their heights, which we correlate to the particles' height-to-length ratios.

Self-Sealing Cementitious Materials by Using Water-Swelling Rubber Particles

PubMed Central

Lv, Leyang; Schlangen, Erik; Xing, Feng

2017-01-01

Water ingress into cracked concrete structures is a serious problem, as it can cause leakage and reinforcement corrosion and thus reduce functionality and safety of the structures. In this study, the application of water-swelling rubber particles for providing the cracked concrete a self-sealing function was developed. The feasibility of applying water-swelling rubber particles and the influence of incorporating water-swelling rubber particles on the mechanical properties of concrete was investigated. The self-sealing efficiency of water-swelling rubber particles with different content and particle size was quantified through a permeability test. The sealing effect of the water swelling rubber particles was monitored by X-ray computed tomography. The experimental results show that, by using 6% of these water swelling rubber particles as a replacement of aggregates in concrete, up to 64% and 61% decrease of water permeability was realized for 0.7 mm and 1.0 mm cracks. Furthermore, when the concrete cracks, the water swelling rubber particles can act as a crack bridging filler, preventing the crack from fully separating the specimens in two pieces. PMID:28829384

Quantifying capital goods for biological treatment of organic waste.

PubMed

Brogaard, Line K; Petersen, Per H; Nielsen, Peter D; Christensen, Thomas H

2015-02-01

Materials and energy used for construction of anaerobic digestion (AD) and windrow composting plants were quantified in detail. The two technologies were quantified in collaboration with consultants and producers of the parts used to construct the plants. The composting plants were quantified based on the different sizes for the three different types of waste (garden and park waste, food waste and sludge from wastewater treatment) in amounts of 10,000 or 50,000 tonnes per year. The AD plant was quantified for a capacity of 80,000 tonnes per year. Concrete and steel for the tanks were the main materials for the AD plant. For the composting plants, gravel and concrete slabs for the pavement were used in large amounts. To frame the quantification, environmental impact assessments (EIAs) showed that the steel used for tanks at the AD plant and the concrete slabs at the composting plants made the highest contribution to Global Warming. The total impact on Global Warming from the capital goods compared to the operation reported in the literature on the AD plant showed an insignificant contribution of 1-2%. For the composting plants, the capital goods accounted for 10-22% of the total impact on Global Warming from composting. © The Author(s) 2015.

Thermophoretic aggregation of particles in a protoplanetary disc

NASA Astrophysics Data System (ADS)

Smith, Francis J.

2018-04-01

Thermophoresis causes particles to move down a temperature gradient to a cooler region of a neutral gas. An example is the temperature gradient in the gas around a large cold object, such as an aggregate of particles, cooled by radiation in a protoplanetary disc. Particles near this aggregate move down the temperature gradient to the aggregate, equivalent to the particles being attracted to it by an inter-particle thermophoretic force. This force is proportional to the temperature difference between gas and aggregate, to the gas density and to the cross-section of the aggregate. The force can be large. For example, calculations based on the equations of motion of the interacting particles show that it can be large enough in an optically thin environment to increase the rate of aggregation by up to six orders of magnitude when an aggregate radius lies between 0.1 μm and 1 mm. From 1 mm to about 10 cm aggregates drift inwards through the gas too quickly for the thermophoretic attraction to increase aggregation significantly; so they grow slowly, causing an observed accumulation of particles at these sizes. Particles above 10 cm move more quickly, causing aggregation due to collisions, but also causing fragmentation. However, calculations show that fragmenting particles and bouncing particles in inelastic collisions often have low enough relative velocities that thermophoresis brings them together again. This allows particles to grow above 1 m, which is otherwise difficult to explain.

Particle image velocimetry for the Surface Tension Driven Convection Experiment using a particle displacement tracking technique

NASA Technical Reports Server (NTRS)

Wernet, Mark P.; Pline, Alexander D.

1991-01-01

The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

Particle image velocimetry for the surface tension driven convection experiment using a particle displacement tracking technique

NASA Technical Reports Server (NTRS)

Wernet, Mark P.; Pline, Alexander D.

1991-01-01

The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

Rice Starch Particle Interactions at Air/Aqueous Interfaces—Effect of Particle Hydrophobicity and Solution Ionic Strength

PubMed Central

McNamee, Cathy E.; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-01-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e., the natural particle found inside the plant, at air/aqueous interfaces, and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film. PMID:29868551

Rice Starch Particle Interactions at Air/Aqueous Interfaces-Effect of Particle Hydrophobicity and Solution Ionic Strength.

PubMed

McNamee, Cathy E; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-01-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e., the natural particle found inside the plant, at air/aqueous interfaces, and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film.

Rice starch particle interactions at air/aqueous interfaces– effect of particle hydrophobicity and solution ionic strength

NASA Astrophysics Data System (ADS)

McNamee, Cathy E.; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-05-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e. the natural particle found inside the plant, at air/aqueous interfaces and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film.

Developments in suspended particle devices (SPD)

NASA Astrophysics Data System (ADS)

Yu, Byung-Seok; Kim, Eung-Soo; Lee, Young-Woo

1997-10-01

Light valve using suspended particles was invented first by Edwin H. Land. But it could not be made to large area because it was a liquid cell containing a suspension of the particles between both transparent conductive layers. For several years, so many trials have been to make a large size of light valve. Recently we could make the light valve of large size which is film type by phase separation and/or emulsification methods. In this paper, we are introducing the light valve film made by HGI.

The large-scale microwave background anisotropy in decaying particle cosmology

NASA Technical Reports Server (NTRS)

Panek, Miroslaw

1988-01-01

The quadrupole anisotropy of the microwave background radiation in cosmological models with decaying particles is investigated. A conservative upper limit on value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z(d) of less than 3-6.

Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

PubMed

Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

2014-09-28

We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

Development of the Small Package Single Particle Soot Photometer with extended range (SP2-XR) and black carbon detection efficiency compared to its predecessor, the SP2

NASA Astrophysics Data System (ADS)

Schulz, H.; Kok, G. L.; Zanatta, M.; Schwarz, J. P.; Herber, A. B.

2016-12-01

Black carbon (BC) aerosol is an important contributor to climate change due to its ability to very efficiently absorb solar radiation. The Single Particle Soot Photometer (SP2) is an instrument that quantifies the refractory mass of individual BC-containing particles with a laser-induced incandescence method. The SP2 has been deployed on ships, at ground based sites, and on research aircraft to quantify BC's mass loadings and microphysical properties. However, the SP2's particle detection range is generally limited to 70-700 nm volume-equivalent diameter for ambient BC. Ambient air typically contains substantial number concentrations below and mass concentrations above the limits of this range. To account for the unquantified particles, it is common to fit a log-normal distribution to the measured size distributions — an approach that leaves the BC community with uncertain results, and a need to learn about the occurrence of very small particles or very large BC aggregates. The SP2 is also large and heavy enough to limit its usability for aircraft and unmanned or towed airborne vehicles. We have developed a miniaturized SP2 to dramatically extend the range of applications for which the SP2 technique can be used. This new instrument, with the additional target of an extended measurement range, has been named the SP2-XR, and incorporates a newly designed optical block with updated electronics for signal recording and on-the-fly processing (gain stitching and peak analysis). The optical block improves the light-collection of both scattered and incandescent light from sampled particles. The target measurement range is 40-1000 nm. At the same time, the SP2-XR weighs less than half of an SP2 (15 kg for the complete system), and about 1/4 the volume ( 20 cm x 20 cm x 40 cm). The instrument software is designed to produce ready to use particle mass and binned size distributions or full particle trace records, according to different scientific needs. Thus, an SP2-XR may

Mass Spectrometry of Single Particles Levitated in an Electrodynamic Balance: Applications to Laboratory Atmospheric Chemistry Research

NASA Astrophysics Data System (ADS)

Birdsall, A.; Krieger, U. K.; Keutsch, F. N.

2017-12-01

Dynamic changes to atmospheric aerosol particle composition (e.g., originating from evaporation/condensation, oxidative aging, or aqueous-phase chemical reactions) impact particle properties with importance for understanding particle effects on climate and human health. These changes can take place over the entire lifetime of an atmospheric particle, which can extend over multiple days. Previous laboratory studies of such processes have included analyzing single particles suspended in a levitation device, such as an electrodynamic balance (EDB), an optical levitator, or an acoustic trap, using optical detection techniques. However, studying chemically complex systems can require an analytical method, such as mass spectrometry, that provides more molecular specificity. Existing work coupling particle levitation with mass spectrometry is more limited and largely has consisted of acoustic levitation of millimeter-sized droplets.In this work an EDB has been coupled with a custom-built ionization source and commercial time-of-flight mass spectrometer (MS) as a platform for laboratory atmospheric chemistry research. Single charged particles (radius 10 μm) have been injected into an EDB, levitated for an arbitrarily long period of time, and then transferred to a vaporization-corona discharge ionization region for MS analysis. By analyzing a series of particles of identical composition, residing in the controlled environment of the EDB for varying times, we can trace the chemical evolution of a particle over hours or days, appropriate timescales for understanding transformations of atmospheric particles.To prove the concept of our EDB-MS system, we have studied the evaporation of particles consisting of polyethylene glycol (PEG) molecules of mixed chain lengths, used as a benchmark system. Our system can quantify the composition of single particles (see Figure for sample spectrum of a single PEG-200 particle: PEG parent ions labeled with m/z, known PEG fragment ions

Iron solubility related to particle sulfur content in source emission and ambient fine particles.

PubMed

Oakes, M; Ingall, E D; Lai, B; Shafer, M M; Hays, M D; Liu, Z G; Russell, A G; Weber, R J

2012-06-19

The chemical factors influencing iron solubility (soluble iron/total iron) were investigated in source emission (e.g., biomass burning, coal fly ash, mineral dust, and mobile exhaust) and ambient (Atlanta, GA) fine particles (PM2.5). Chemical properties (speciation and mixing state) of iron-containing particles were characterized using X-ray absorption near edge structure (XANES) spectroscopy and micro-X-ray fluorescence measurements. Bulk iron solubility (soluble iron/total iron) of the samples was quantified by leaching experiments. Major differences were observed in iron solubility in source emission samples, ranging from low solubility (<1%, mineral dust and coal fly ash) up to 75% (mobile exhaust and biomass burning emissions). Differences in iron solubility did not correspond to silicon content or Fe(II) content. However, source emission and ambient samples with high iron solubility corresponded to the sulfur content observed in single particles. A similar correspondence between bulk iron solubility and bulk sulfate content in a series of Atlanta PM2.5 fine particle samples (N = 358) further supported this trend. In addition, results of linear combination fitting experiments show the presence of iron sulfates in several high iron solubility source emission and ambient PM2.5 samples. These results suggest that the sulfate content (related to the presence of iron sulfates and/or acid-processing mechanisms by H(2)SO(4)) of iron-containing particles is an important proxy for iron solubility.

High-Performance Reactive Particle Tracking with Adaptive Representation

NASA Astrophysics Data System (ADS)

Schmidt, M.; Benson, D. A.; Pankavich, S.

2017-12-01

Lagrangian particle tracking algorithms have been shown to be effective tools for modeling chemical reactions in imperfectly-mixed media. One disadvantage of these algorithms is the possible need to employ large numbers of particles in simulations, depending on the concentration covariance structure, and these large particle numbers can lead to long computation times. Two distinct approaches have recently arisen to overcome this. One method employs spatial kernels that are related to a specified, reduced particle number; however, over-wide kernels, dictated by a very low particle number, lead to an excess of reaction calculations and cause a reduction in performance. Another formulation involves hybrid particles that carry multiple species of reactant, wherein each particle is treated as its own well-mixed volume, obviating the need for large numbers of particles for each species but still requiring a fixed number of hybrid particles. Here, we combine these two approaches and demonstrate an improved method for simulating a given system in a computationally efficient manner. Additionally, the independent nature of transport and reaction calculations in this approach allows for significant gains via parallelization in an MPI or OpenMP context. For benchmarking, we choose a CO2 injection simulation with dissolution and precipitation of calcite and dolomite, allowing us to derive the proper treatment of interaction between solid and aqueous phases.

Thermodynamics of phase-separating nanoalloys: Single particles and particle assemblies

NASA Astrophysics Data System (ADS)

Fèvre, Mathieu; Le Bouar, Yann; Finel, Alphonse

2018-05-01

The aim of this paper is to investigate the consequences of finite-size effects on the thermodynamics of nanoparticle assemblies and isolated particles. We consider a binary phase-separating alloy with a negligible atomic size mismatch, and equilibrium states are computed using off-lattice Monte Carlo simulations in several thermodynamic ensembles. First, a semi-grand-canonical ensemble is used to describe infinite assemblies of particles with the same size. When decreasing the particle size, we obtain a significant decrease of the solid/liquid transition temperatures as well as a growing asymmetry of the solid-state miscibility gap related to surface segregation effects. Second, a canonical ensemble is used to analyze the thermodynamic equilibrium of finite monodisperse particle assemblies. Using a general thermodynamic formulation, we show that a particle assembly may split into two subassemblies of identical particles. Moreover, if the overall average canonical concentration belongs to a discrete spectrum, the subassembly concentrations are equal to the semi-grand-canonical equilibrium ones. We also show that the equilibrium of a particle assembly with a prescribed size distribution combines a size effect and the fact that a given particle size assembly can adopt two configurations. Finally, we have considered the thermodynamics of an isolated particle to analyze whether a phase separation can be defined within a particle. When studying rather large nanoparticles, we found that the region in which a two-phase domain can be identified inside a particle is well below the bulk phase diagram, but the concentration of the homogeneous core remains very close to the bulk solubility limit.

Effects of particle-fluid density ratio on the interactions between the turbulent channel flow and finite-size particles

NASA Astrophysics Data System (ADS)

Yu, Zhaosheng; Lin, Zhaowu; Shao, Xueming; Wang, Lian-Ping

2017-09-01

A parallel direct-forcing fictitious domain method is employed to perform fully resolved numerical simulations of turbulent channel flow laden with finite-size particles. The effects of the particle-fluid density ratio on the turbulence modulation in the channel flow are investigated at the friction Reynolds number of 180, the particle volume fraction of 0.84 % , and the particle-fluid density ratio ranging from 1 to 104.2. The results show that the variation of the flow drag with the particle-fluid density ratio is not monotonic, with a larger flow drag for the density ratio of 10.42, compared to those of unity and 104.2. A significant drag reduction by the particles is observed for large particle-fluid density ratios during the transient stage, but not at the statistically stationary stage. The intensity of particle velocity fluctuations generally decreases with increasing particle inertia, except that the particle streamwise root-mean-square velocity and streamwise-transverse velocity correlation in the near-wall region are largest at the density ratio of the order of 10. The averaged momentum equations are derived with the spatial averaging theorem and are used to analyze the mechanisms for the effects of the particles on the flow drag. The results indicate that the drag-reduction effect due to the decrease in the fluid Reynolds shear stress is counteracted by the drag-enhancement effect due to the increase in the total particle stress or the interphase drag force for the large particle-inertia case. The sum of the total Reynolds stress and particle inner stress contributions to the flow drag is largest at the density ratio of the order of 10, which is the reason for the largest flow drag at this density ratio. The interphase drag force obtained from the averaged momentum equation (the balance theory) is significantly smaller than (but agrees qualitatively with) that from the empirical drag formula based on the phase-averaged slip velocity for large density

Effects of particle-fluid density ratio on the interactions between the turbulent channel flow and finite-size particles.

PubMed

Yu, Zhaosheng; Lin, Zhaowu; Shao, Xueming; Wang, Lian-Ping

2017-09-01

A parallel direct-forcing fictitious domain method is employed to perform fully resolved numerical simulations of turbulent channel flow laden with finite-size particles. The effects of the particle-fluid density ratio on the turbulence modulation in the channel flow are investigated at the friction Reynolds number of 180, the particle volume fraction of 0.84%, and the particle-fluid density ratio ranging from 1 to 104.2. The results show that the variation of the flow drag with the particle-fluid density ratio is not monotonic, with a larger flow drag for the density ratio of 10.42, compared to those of unity and 104.2. A significant drag reduction by the particles is observed for large particle-fluid density ratios during the transient stage, but not at the statistically stationary stage. The intensity of particle velocity fluctuations generally decreases with increasing particle inertia, except that the particle streamwise root-mean-square velocity and streamwise-transverse velocity correlation in the near-wall region are largest at the density ratio of the order of 10. The averaged momentum equations are derived with the spatial averaging theorem and are used to analyze the mechanisms for the effects of the particles on the flow drag. The results indicate that the drag-reduction effect due to the decrease in the fluid Reynolds shear stress is counteracted by the drag-enhancement effect due to the increase in the total particle stress or the interphase drag force for the large particle-inertia case. The sum of the total Reynolds stress and particle inner stress contributions to the flow drag is largest at the density ratio of the order of 10, which is the reason for the largest flow drag at this density ratio. The interphase drag force obtained from the averaged momentum equation (the balance theory) is significantly smaller than (but agrees qualitatively with) that from the empirical drag formula based on the phase-averaged slip velocity for large density

Small particles big effect? - Investigating ice nucleation abilities of soot particles

NASA Astrophysics Data System (ADS)

Mahrt, Fabian; David, Robert O.; Lohmann, Ulrike; Stopford, Chris; Wu, Zhijun; Kanji, Zamin A.

2017-04-01

emissions. Collected particles will be re-suspended and aerosolized using an atomizer (TSI, model 3076) and dried by a diffusion drier prior to ice nucleation experiments. A Particle Phase Discriminator (PPD) coupled to HINC will allow discrimination of size-resolved liquid and ice hydrometeors formed on the atmospheric soot particles injected into the CFDC. This will allow to more precisely quantify the microphysical properties of these particles in cloud processes for the conditions tested. To our knowledge this is the first time such a coupling is done for atmospheric soot particles. Results show different activation behavior of the soot over the temperature range investigated. While CAST-brown soot needs conditions above water saturation to show any freezing, some of the commercial soot samples show heterogeneous ice nucleation well below water saturation for the cirrus conditions. For the mixed-phase cloud conditions all soot types show droplet activation for high water supersaturation.

Capturing the Large Scale Behavior of Many Particle Systems Through Coarse-Graining

NASA Astrophysics Data System (ADS)

Punshon-Smith, Samuel

This dissertation is concerned with two areas of investigation: the first is understanding the mathematical structures behind the emergence of macroscopic laws and the effects of small scales fluctuations, the second involves the rigorous mathematical study of such laws and related questions of well-posedness. To address these areas of investigation the dissertation involves two parts: Part I concerns the theory of coarse-graining of many particle systems. We first investigate the mathematical structure behind the Mori-Zwanzig (projection operator) formalism by introducing two perturbative approaches to coarse-graining of systems that have an explicit scale separation. One concerns systems with little dissipation, while the other concerns systems with strong dissipation. In both settings we obtain an asymptotic series of `corrections' to the limiting description which are small with respect to the scaling parameter, these corrections represent the effects of small scales. We determine that only certain approximations give rise to dissipative effects in the resulting evolution. Next we apply this framework to the problem of coarse-graining the locally conserved quantities of a classical Hamiltonian system. By lumping conserved quantities into a collection of mesoscopic cells, we obtain, through a series of approximations, a stochastic particle system that resembles a discretization of the non-linear equations of fluctuating hydrodynamics. We study this system in the case that the transport coefficients are constant and prove well-posedness of the stochastic dynamics. Part II concerns the mathematical description of models where the underlying characteristics are stochastic. Such equations can model, for instance, the dynamics of a passive scalar in a random (turbulent) velocity field or the statistical behavior of a collection of particles subject to random environmental forces. First, we study general well-posedness properties of stochastic transport equation with

Effect of indirect non-thermal plasma on particle size distribution and composition of diesel engine particles

NASA Astrophysics Data System (ADS)

Linbo, GU; Yixi, CAI; Yunxi, SHI; Jing, WANG; Xiaoyu, PU; Jing, TIAN; Runlin, FAN

2017-11-01

To explore the effect of the gas source flow rate on the actual diesel exhaust particulate matter (PM), a test bench for diesel engine exhaust purification was constructed, using indirect non-thermal plasma technology. The effects of different gas source flow rates on the quantity concentration, composition, and apparent activation energy of PM were investigated, using an engine exhaust particle sizer and a thermo-gravimetric analyzer. The results show that when the gas source flow rate was large, not only the maximum peak quantity concentrations of particles had a large drop, but also the peak quantity concentrations shifted to smaller particle sizes from 100 nm to 80 nm. When the gas source flow rate was 10 L min-1, the total quantity concentration greatly decreased where the removal rate of particles was 79.2%, and the variation of the different mode particle proportion was obvious. Non-thermal plasma (NTP) improved the oxidation ability of volatile matter as well as that of solid carbon. However, the NTP gas source rate had little effects on oxidation activity of volatile matter, while it strongly influenced the oxidation activity of solid carbon. Considering the quantity concentration and oxidation activity of particles, a gas source flow rate of 10 L min-1 was more appropriate for the purification of particles.

Understanding the dynamics of superparamagnetic particles under the influence of high field gradient arrays

NASA Astrophysics Data System (ADS)

Barnsley, Lester C.; Carugo, Dario; Aron, Miles; Stride, Eleanor

2017-03-01

The aim of this study was to characterize the behaviour of superparamagnetic particles in magnetic drug targeting (MDT) schemes. A 3-dimensional mathematical model was developed, based on the analytical derivation of the trajectory of a magnetized particle suspended inside a fluid channel carrying laminar flow and in the vicinity of an external source of magnetic force. Semi-analytical expressions to quantify the proportion of captured particles, and their relative accumulation (concentration) as a function of distance along the wall of the channel were also derived. These were expressed in terms of a non-dimensional ratio of the relevant physical and physiological parameters corresponding to a given MDT protocol. The ability of the analytical model to assess magnetic targeting schemes was tested against numerical simulations of particle trajectories. The semi-analytical expressions were found to provide good first-order approximations for the performance of MDT systems in which the magnetic force is relatively constant over a large spatial range. The numerical model was then used to test the suitability of a range of different designs of permanent magnet assemblies for MDT. The results indicated that magnetic arrays that emit a strong magnetic force that varies rapidly over a confined spatial range are the most suitable for concentrating magnetic particles in a localized region. By comparison, commonly used magnet geometries such as button magnets and linear Halbach arrays result in distributions of accumulated particles that are less efficient for delivery. The trajectories predicted by the numerical model were verified experimentally by acoustically focusing magnetic microbeads flowing in a glass capillary channel, and optically tracking their path past a high field gradient Halbach array.

Transport of active ellipsoidal particles in ratchet potentials

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

Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn; Wu, Jian-Chun

2014-03-07

Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, whilemore » for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)« less

Some Progress in Large-Eddy Simulation using the 3-D Vortex Particle Method

NASA Technical Reports Server (NTRS)

Winckelmans, G. S.

1995-01-01

This two-month visit at CTR was devoted to investigating possibilities in LES modeling in the context of the 3-D vortex particle method (=vortex element method, VEM) for unbounded flows. A dedicated code was developed for that purpose. Although O(N(sup 2)) and thus slow, it offers the advantage that it can easily be modified to try out many ideas on problems involving up to N approx. 10(exp 4) particles. Energy spectrums (which require O(N(sup 2)) operations per wavenumber) are also computed. Progress was realized in the following areas: particle redistribution schemes, relaxation schemes to maintain the solenoidal condition on the particle vorticity field, simple LES models and their VEM extension, possible new avenues in LES. Model problems that involve strong interaction between vortex tubes were computed, together with diagnostics: total vorticity, linear and angular impulse, energy and energy spectrum, enstrophy. More work is needed, however, especially regarding relaxation schemes and further validation and development of LES models for VEM. Finally, what works well will eventually have to be incorporated into the fast parallel tree code.

The abundances of hydrogen, helium, oxygen, and iron accelerated in large solar particle events

NASA Technical Reports Server (NTRS)

Mazur, J. E.; Mason, G. M.; Klecker, B.; Mcguire, R. E.

1993-01-01

Energy spectra measured in 10 large flares with the University of Maryland/Max-Planck-Institut sensors on ISEE I and Goddard Space Flight Center sensors on IMP 8 allowed us to determine the average H, He, O, and Fe abundances as functions of energy in the range of about 0.3-80 MeV/nucleon. Model fits to the spectra of individual events using the predictions of a steady state stochastic acceleration model with rigidity-dependent diffusion provided a means of interpolating small portions of the energy spectra not measured with the instrumentation. Particles with larger mass-to-charge ratios were relatively less abundant at higher energies in the flare-averaged composition. The Fe/O enhancement at low SEP energies was less than the Fe/O ratios observed in He-3-rich flares. Unlike the SEP composition averaged above 5 MeV/nucleon, the average SEP abundances above 0.3 MeV/nucleon were similar to the average solar wind.

Analysis of pinching in deterministic particle separation

NASA Astrophysics Data System (ADS)

Risbud, Sumedh; Luo, Mingxiang; Frechette, Joelle; Drazer, German

2011-11-01

We investigate the problem of spherical particles vertically settling parallel to Y-axis (under gravity), through a pinching gap created by an obstacle (spherical or cylindrical, center at the origin) and a wall (normal to X axis), to uncover the physics governing microfluidic separation techniques such as deterministic lateral displacement and pinched flow fractionation: (1) theoretically, by linearly superimposing the resistances offered by the wall and the obstacle separately, (2) computationally, using the lattice Boltzmann method for particulate systems and (3) experimentally, by conducting macroscopic experiments. Both, theory and simulations, show that for a given initial separation between the particle centre and the Y-axis, presence of a wall pushes the particles closer to the obstacle, than its absence. Experimentally, this is expected to result in an early onset of the short-range repulsive forces caused by solid-solid contact. We indeed observe such an early onset, which we quantify by measuring the asymmetry in the trajectories of the spherical particles around the obstacle. This work is partially supported by the National Science Foundation Grant Nos. CBET- 0731032, CMMI-0748094, and CBET-0954840.

Anisotropic particles strengthen granular pillars under compression

NASA Astrophysics Data System (ADS)

Harrington, Matt; Durian, Douglas J.

2018-01-01

We probe the effects of particle shape on the global and local behavior of a two-dimensional granular pillar, acting as a proxy for a disordered solid, under uniaxial compression. This geometry allows for direct measurement of global material response, as well as tracking of all individual particle trajectories. In general, drawing connections between local structure and local dynamics can be challenging in amorphous materials due to lower precision of atomic positions, so this study aims to elucidate such connections. We vary local interactions by using three different particle shapes: discrete circular grains (monomers), pairs of grains bonded together (dimers), and groups of three bonded in a triangle (trimers). We find that dimers substantially strengthen the pillar and the degree of this effect is determined by orientational order in the initial condition. In addition, while the three particle shapes form void regions at distinct rates, we find that anisotropies in the local amorphous structure remain robust through the definition of a metric that quantifies packing anisotropy. Finally, we highlight connections between local deformation rates and local structure.

A small-angle large-acceptance detection system for hadrons

NASA Astrophysics Data System (ADS)

Kalantar-Nayestanaki, N.; Bacelar, J. C. S.; Brandenburg, S.; Huisman, H.; Messchendorp, J. G.; Mul, F. A.; Schadmand, S.; van der Schaaf, K.; Schippers, J. M.; Volkerts, M.

2000-04-01

The performance of a segmented large-acceptance detector, capable of measuring particles at small forward angles, is presented. The Small-Angle Large-Acceptance Detector (SALAD), was built to handle very high rates of particles impinging on the detector. Particles down to a few MeV can be detected with it. The position of charged particles is measured by two Multi-Wire Proportional Chambers while scintillator blocks are used to measure the energy of the detected particle. A stack of thin scintillators placed behind the energy detectors allows for a hardware rejection (veto) of high-energy particles going through the scintillator blocks.

Modeling Evaporation and Particle Assembly in Colloidal Droplets.

PubMed

Zhao, Mingfei; Yong, Xin

2017-06-13

Evaporation-induced assembly of nanoparticles in a drying droplet is of great importance in many engineering applications, including printing, coating, and thin film processing. The investigation of particle dynamics in evaporating droplets can provide fundamental hydrodynamic insight for revealing the processing-structure relationship in the particle self-organization induced by solvent evaporation. We develop a free-energy-based multiphase lattice Boltzmann method coupled with Brownian dynamics to simulate evaporating colloidal droplets on solid substrates with specified wetting properties. The influence of interface-bound nanoparticles on the surface tension and evaporation of a flat liquid-vapor interface is first quantified. The results indicate that the particles at the interface reduce surface tension and enhance evaporation flux. For evaporating particle-covered droplets on substrates with different wetting properties, we characterize the increase of evaporate rate via measuring droplet volume. We find that droplet evaporation is determined by the number density and circumferential distribution of interfacial particles. We further correlate particle dynamics and assembly to the evaporation-induced convection in the bulk and on the surface of droplet. Finally, we observe distinct final deposits from evaporating colloidal droplets with bulk-dispersed and interface-bound particles. In addition, the deposit pattern is also influenced by the equilibrium contact angle of droplet.

Characterization of Gas and Particle Emissions from Laboratory Burns of Peat

EPA Science Inventory

Peat cores collected from two locations in eastern North Carolina (NC, USA) were burned in a laboratory facility to characterize emissions during simulated field combustion. Particle and gas samples were analyzed to quantify emission factors for particulate matter (PM2.5), organi...

Quantifying Young's moduli of protein fibrils and particles with bimodal force spectroscopy.

PubMed

Gilbert, Jay; Charnley, Mirren; Cheng, Christopher; Reynolds, Nicholas P; Jones, Owen G

2017-10-19

Force spectroscopy is a means of obtaining mechanical information of individual nanometer-scale structures in composite materials, such as protein assemblies for use in consumer films or gels. As a recently developed force spectroscopy technique, bimodal force spectroscopy relates frequency shifts in cantilevers simultaneously excited at multiple frequencies to the elastic properties of the contacted material, yet its utility for quantitative characterization of biopolymer assemblies has been limited. In this study, a linear correlation between experimental frequency shift and Young's modulus of polymer films was used to calibrate bimodal force spectroscopy and quantify Young's modulus of two protein nanostructures: β-lactoglobulin fibrils and zein nanoparticles. Cross-sectional Young's modulus of protein fibrils was determined to be 1.6 GPa while the modulus of zein nanoparticles was determined as 854 MPa. Parallel measurement of β-lactoglobulin fibril by a competing pulsed-force technique found a higher cross-sectional Young's modulus, highlighting the importance of comparative calibration against known standards in both pulsed and bimodal force spectroscopies. These findings demonstrate a successful procedure for measuring mechanical properties of individual protein assemblies with potential use in biological or packaging applications using bimodal force spectroscopy.

Experimental investigation of the hydrodynamics in pockmarks using particle tracking velocimetry

NASA Astrophysics Data System (ADS)

Pau, Mauro; Gisler, Galen; Hammer, Øyvind

2014-02-01

Water tank experiments were performed in order to investigate the behaviour of currents in pockmarks. A particle-seeded flow was visualised and quantified with the aid of the particle tracking velocimetry technique. The employed analogue pockmark is a 1:100 idealised scale model of a natural pockmark, while the highest Reynolds number in the experiments was one order of magnitude smaller than in nature. Interaction of the flow with the pockmark geometry resulted in an upwelling current downstream of the pockmark centre, along with enhanced water turbulence in the depression. Scaling-up the experimental measurements, it is found that the upwelling would be capable of preventing the settling of particles as large as very fine sand. Furthermore, the increased turbulence would support the suspended fine material, which can thus be transported away before settling. The net effect for a variable-direction near-bed current over long periods of time would be to winnow the settling sediments and reduce the sedimentation rate in pockmarks. These mechanisms may be responsible for the observed lack of sediment infill and the typical presence of relatively coarser sediments inside pockmarks compared to the surrounding bed. In contrast, sediments transported as bedload are likely to be deposited in pockmarks because of the weakening of near-bed currents as well as lateral flow convergence associated with the upwelling. Bedload, however, may not be the dominant mode of sediment transport in areas covered by cohesive sediments, where pockmarks are found.

Hydrodynamic Stability Analysis of Particle-Laden Solid Rocket Motors

NASA Astrophysics Data System (ADS)

Elliott, T. S.; Majdalani, J.

2014-11-01

Fluid-wall interactions within solid rocket motors can result in parietal vortex shedding giving rise to hydrodynamic instabilities, or unsteady waves, that translate into pressure oscillations. The oscillations can result in vibrations observed by the rocket, rocket subsystems, or payload, which can lead to changes in flight characteristics, design failure, or other undesirable effects. For many years particles have been embedded in solid rocket propellants with the understanding that their presence increases specific impulse and suppresses fluctuations in the flowfield. This study utilizes a two dimensional framework to understand and quantify the aforementioned two-phase flowfield inside a motor case with a cylindrical grain perforation. This is accomplished through the use of linearized Navier-Stokes equations with the Stokes drag equation and application of the biglobal ansatz. Obtaining the biglobal equations for analysis requires quantification of the mean flowfield within the solid rocket motor. To that end, the extended Taylor-Culick form will be utilized to represent the gaseous phase of the mean flowfield while the self-similar form will be employed for the particle phase. Advancing the mean flowfield by quantifying the particle mass concentration with a semi-analytical solution the finalized mean flowfield is combined with the biglobal equations resulting in a system of eight partial differential equations. This system is solved using an eigensolver within the framework yielding the entire spectrum of eigenvalues, frequency and growth rate components, at once. This work will detail the parametric analysis performed to demonstrate the stabilizing and destabilizing effects of particles within solid rocket combustion.

Virus-mimetic polyplex particles for systemic and inflammation-specific targeted delivery of large genetic contents.

PubMed

Kang, S; Lu, K; Leelawattanachai, J; Hu, X; Park, S; Park, T; Min, I M; Jin, M M

2013-11-01

Systemic and target-specific delivery of large genetic contents has been difficult to achieve. Although viruses effortlessly deliver kilobase-long genome into cells, its clinical use has been hindered by serious safety concerns and the mismatch between native tropisms and desired targets. Nonviral vectors, in contrast, are limited by low gene transfer efficiency and inherent cytotoxicity. Here we devised virus-mimetic polyplex particles (VMPs) based on electrostatic self-assembly among polyanionic peptide (PAP), cationic polymer polyethyleneimine (PEI) and nucleic acids. We fused PAP to the engineered ligand-binding domain of integrin αLβ2 to target intercellular adhesion molecule-1 (ICAM-1), an inducible marker of inflammation. Fully assembled VMPs packaged large genetic contents, bound specifically to target molecules, elicited receptor-mediated endocytosis and escaped endosomal pathway, resembling intracellular delivery processes of viruses. Unlike conventional PEI-mediated transfection, molecular interaction-dependent gene delivery of VMPs was unaffected by the presence of serum and achieved higher efficiency without toxicity. By targeting overexpressed ICAM-1, VMPs delivered genes specifically to inflamed endothelial cells and macrophages both in vitro and in vivo. Simplicity and versatility of the platform and inflammation-specific delivery may open up opportunities for multifaceted gene therapy that can be translated into the clinic and treat a broad range of debilitating immune and inflammatory diseases.

Quantifying morphological changes of cape-related shoals

NASA Astrophysics Data System (ADS)

Paniagua-Arroyave, J. F.; Adams, P. N.; Parra, S. M.; Valle-Levinson, A.

2017-12-01

The rising demand for marine resources has motivated the study of inner shelf transport processes, especially in locations with highly-developed coastlines, endangered-species habitats, and valuable economic resources. These characteristics are found at Cape Canaveral shoals, on the Florida Atlantic coast, where transport dynamics and morphological evolution are not well understood. To study morphological changes at these shoals, two sets of paired upward- and downward-pointing acoustic Doppler current profilers (ADCPs) were deployed in winter 2015-2016. One set was deployed at the inner swale of Shoal E, 20 km southeast of the cape tip in 13 m depth, while the other set was located at the edge of Southeast shoal in 5 m deep. Upward-pointing velocity profiles and suspended particle concentrations were implemented in the Exner equation to quantify instantaneous rates of change in bed elevation. This computation includes changes in sediment concentration and the advection of suspended particles, but does not account for spatial gradients in bed-load fluxes and water velocities. The results of the computation were then compared to bed change rates measured directly by the downward-pointing ADCPs. At the easternmost ridge, quantified bed elevation change rates ranged from -7×10-7 to 4×10-7 m/s, and those at the inner swale ranged from -4×10-7 to 8×10-7 m/s. These values were two orders of magnitude smaller than rates measured by downward-pointing ADCPs. Moreover, the cumulative changes were two orders of magnitude larger at the ridge (-0.33 m, downward, and -0.13, m upward) than at the inner swale (cf. -6×10-3 m, downward, and 3×10-3 m, upward). These values suggest that bedform migration may be occurring at the ridge, that suspended sediments account for up to 30% of total bed changes, and that gradients in bed-load fluxes exert control on morphological change over the shoals. Despite uncertainties related to the ADCP-derived sediment concentrations, these

Large Energetic Particle Pressures in Solar Cycles 23 and 24

NASA Astrophysics Data System (ADS)

Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A. F.; Wimmer-Schweingruber, R. F.; Berger, L.

2017-09-01

We study periods of elevated energetic particle intensities observed at the L1 Sun-Earth Lagrangian point when the partial energy density associated with energetic (≥80 keV) particles (PEP) dominates that of the local magnetic field (PB) and thermal plasma populations (PPLS). These periods are not uncommon and are frequently observed prior to the passage of interplanetary (IP) shocks. Because of the significant decreases in key solar wind parameters observed during solar cycle 24 [e.g., 1], we were motivated to perform a comparative statistical analysis to determine if the occurrence rate of periods when PEP exceeded PB or PPLS, or both, differed between solar cycles 23 and 24. We find that the general decrease of PB and PPLS in solar cycle 24 was also accompanied by a general decrease of periods with elevated PEP. The result is that solar cycle 24 showed a lower number of time intervals dominated by PEP. We analyze whether these differences can be related to the properties of the IP shocks observed at L1. Incomplete datasets of shock parameters do not show significant differences between solar cycles 23 and 24 that would allow us to explain the difference in the number of periods with PEP>PB and PEP>PPLS. We analyze then the averaged plasma parameters measured in the upstream region of the shocks and find significantly lower solar wind proton temperatures and magnetic field magnitude upstream of IP shocks in solar cycle 24 compared with those in solar cycle 23. These factors, together with the lower level of solar activity, may explain the lower particle intensities in solar cycle 24 and hence the fewer events with PEP>PB and PEP>PPLS.

Quantifying the seismicity on Taiwan

NASA Astrophysics Data System (ADS)

Wu, Yi-Hsuan; Chen, Chien-Chih; Turcotte, Donald L.; Rundle, John B.

2013-07-01

We quantify the seismicity on the island of Taiwan using the frequency-magnitude statistics of earthquakes since 1900. A break in Gutenberg-Richter scaling for large earthquakes in global seismicity has been observed, this break is also observed in our Taiwan study. The seismic data from the Central Weather Bureau Seismic Network are in good agreement with the Gutenberg-Richter relation taking b ≈ 1 when M < 7. For large earthquakes, M ≥ 7, the seismic data fit Gutenberg-Richter scaling with b ≈ 1.5. If the Gutenberg-Richter scaling for M < 7 earthquakes is extrapolated to larger earthquakes, we would expect a M > 8 earthquake in the study region about every 25 yr. However, our analysis shows a lower frequency of occurrence of large earthquakes so that the expected frequency of M > 8 earthquakes is about 200 yr. The level of seismicity for smaller earthquakes on Taiwan is about 12 times greater than in Southern California and the possibility of a M ≈ 9 earthquake north or south of Taiwan cannot be ruled out. In light of the Fukushima, Japan nuclear disaster, we also discuss the implications of our study for the three operating nuclear power plants on the coast of Taiwan.

Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

PubMed

Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

2013-02-11

We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine.

Improving particle filters in rainfall-runoff models: application of the resample-move step and development of the ensemble Gaussian particle filter

NASA Astrophysics Data System (ADS)

Plaza Guingla, D. A.; Pauwels, V. R.; De Lannoy, G. J.; Matgen, P.; Giustarini, L.; De Keyser, R.

2012-12-01

The objective of this work is to analyze the improvement in the performance of the particle filter by including a resample-move step or by using a modified Gaussian particle filter. Specifically, the standard particle filter structure is altered by the inclusion of the Markov chain Monte Carlo move step. The second choice adopted in this study uses the moments of an ensemble Kalman filter analysis to define the importance density function within the Gaussian particle filter structure. Both variants of the standard particle filter are used in the assimilation of densely sampled discharge records into a conceptual rainfall-runoff model. In order to quantify the obtained improvement, discharge root mean square errors are compared for different particle filters, as well as for the ensemble Kalman filter. First, a synthetic experiment is carried out. The results indicate that the performance of the standard particle filter can be improved by the inclusion of the resample-move step, but its effectiveness is limited to situations with limited particle impoverishment. The results also show that the modified Gaussian particle filter outperforms the rest of the filters. Second, a real experiment is carried out in order to validate the findings from the synthetic experiment. The addition of the resample-move step does not show a considerable improvement due to performance limitations in the standard particle filter with real data. On the other hand, when an optimal importance density function is used in the Gaussian particle filter, the results show a considerably improved performance of the particle filter.