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Sample records for single-particle foucault oscillator

  1. Change of the plane of oscillation of a Foucault pendulum from simple pictures

    NASA Astrophysics Data System (ADS)

    Jordan, Thomas F.; Maps, J.

    2010-11-01

    The change of the plane of oscillation of a Foucault pendulum is calculated without using equations of motion, the Gauss-Bonnet theorem, parallel transport, or assumptions that are difficult to explain.

  2. Single particle calculations for a Woods-Saxon potential with triaxial deformations, and large Cartesian oscillator basis

    NASA Astrophysics Data System (ADS)

    Mohammed-Azizi, B.; Medjadi, D. E.

    2004-01-01

    We present a computer program which solves the Schrodinger equation of the stationary states for an average nuclear potential of Woods-Saxon type. In this work, we take specifically into account triaxial (i.e. ellipsoidal) nuclear surfaces. The deformation is specified by the usual Bohr parameters. The calculations are carried out in two stages. In the first, one calculates the representative matrix of the Hamiltonian in the Cartesian oscillator basis. In the second stage one diagonalizes this matrix with the help of subroutines of the Eispack library. If it is wished, one can calculate all eigenvalues, or only the part of the eigenvalues that are contained in a fixed interval defined in advance. In this latter case the eigenvectors are given conjointly. The program is very rapid, and the run-time is mainly used for the diagonalization. Thus, it is possible to use a significant number of the basis states in order to insure a best convergence of the results. Program summaryProgram obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Title of program:Triaxial Catalogue number:ADSK Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSK Licensing provisions:None Computer:PC. AMD Athlon 1000 MHz Hard disk:40 Go Ram:256 Mo Swap file:4 Go Operating system:WINDOWS XP Software used:Microsoft Visual Fortran 5.0A (with full optimizations in the settings project options) Programming language:Fortran 77/90 (double precision) Number of bits in a word:32 Number of lines:7662 No. of bytes in distributed program, including test data, etc.:174 601 Distribution format:tar gzip file Nature of the problem: The single particle energies and the single particle wave functions are calculated from one-body Hamiltonian including a central field of Woods-Saxon type, a spin-orbit interaction, and the Coulomb potential for the protons. We consider only ellipsoidal (triaxial) shapes. The deformation of the nuclear shape is fixed by the usual Bohr parameters ( β,

  3. Single particle calculations for a Woods Saxon potential with triaxial deformations, and large Cartesian oscillator basis (new version code)

    NASA Astrophysics Data System (ADS)

    Mohammed-Azizi, B.; Medjadi, D. E.

    2007-05-01

    We present a new version of the computer program which solves the Schrödinger equation of the stationary states for an average nuclear potential of Woods-Saxon type. In this work, we take specifically into account triaxial (i.e. ellipsoidal) nuclear surfaces. The deformation is specified by the usual Bohr parameters. The calculations are carried out in two stages. In the first, one calculates the representative matrix of the Hamiltonian in the Cartesian oscillator basis. In the second stage one diagonalizes this matrix with the help of subroutines of the EISPACK library. This new version calculates all the eigenvalues up to a given cutoff energy, and gives the components of the corresponding eigenfunctions. For a more convenient handling, these results are stored simultaneously in the computer memory, and on a files. Program summaryTitle of program:Triaxial2007 Catalogue identifier:ADSK_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSK_v2_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Summary of revision:One input file instead two. Reduced number of input parameters. Storage of eigenvalues and eigenvectors in memory in a very simple way which makes the code very convenient to the user. Reasons for the new version: More convenient handling of the eigenvectors Catalogue number old version: ADSK Catalogue number new version:ADSK_v2_0 Journal: Computer Physics Commun. 156 (2004) 241-282 Licensing provisions: none Computer: PC Pentium 4, 2600 MHz Hard disk: 40 Gb RAM: 256 Mb Swap file: 4 Gb Operating system: WINDOWS XP Software used: Compaq Visual FORTRAN (with full optimizations in the settings project options) Programming language used:Fortran 77/90 (double precision) Number of bits in a word: 32 No. of lines in distributed program, including test data, etc.:4058 No. of bytes in distributed program, including test data, etc.:75 590 Distribution format:tar.gz Nature of the problem: The single particle energies

  4. Foucault Pendulum without Driving

    NASA Astrophysics Data System (ADS)

    Yamashita, Yoshifumi

    2016-06-01

    Foucault pendulums are two-dimensional harmonic oscillators to which the Coriolis force is applied. The Foucault parameter ΩF is the ideal rate of rotation of the plane of oscillation due to the Coriolis force. Kamerlingh Onnes pointed out that the actual behavior of Foucault pendulums can be understood only by taking into account the unavoidable mechanical asymmetry, i.e., the difference between the frequency in the X-direction and that in the Y-direction, which is called the asymmetry parameter δ. Our equations of motion for Foucault pendulums are linear and their solutions are easily obtained. We are interested in slowly varying rotations of the plane of oscillation, where the angle of rotation is denoted by φ. The motion of the bob consists of rapid simple oscillations and the slow rotations mentioned above. Eliminating the rapid oscillations, we obtain an analytic expression for tan 2φ, which is a periodic function with period π /√{Ω {F}2 + δ 2} . The graphs of the rotation φ versus time t have two distinct appearances. Under the condition ΩF ≥ δ|cos(2θ)| (θ is the initial value of φ), φ decreases monotonically, which is the behavior expected for Foucault pendulums. Otherwise φ repeatedly increases and decreases, which is the behavior of pendulums describing Lissajous figures. The vertical component of angular momentum is also calculated analytically.

  5. Foucault Pendulum without Driving

    NASA Astrophysics Data System (ADS)

    Yamashita, Yoshifumi

    2016-06-01

    Foucault pendulums are two-dimensional harmonic oscillators to which the Coriolis force is applied. The Foucault parameter ΩF is the ideal rate of rotation of the plane of oscillation due to the Coriolis force. Kamerlingh Onnes pointed out that the actual behavior of Foucault pendulums can be understood only by taking into account the unavoidable mechanical asymmetry, i.e., the difference between the frequency in the X-direction and that in the Y-direction, which is called the asymmetry parameter δ. Our equations of motion for Foucault pendulums are linear and their solutions are easily obtained. We are interested in slowly varying rotations of the plane of oscillation, where the angle of rotation is denoted by φ. The motion of the bob consists of rapid simple oscillations and the slow rotations mentioned above. Eliminating the rapid oscillations, we obtain an analytic expression for tan 2φ, which is a periodic function with period π /√{Ω F2 + δ 2} . The graphs of the rotation φ versus time t have two distinct appearances. Under the condition ΩF ≥ δ|cos(2θ)| (θ is the initial value of φ), φ decreases monotonically, which is the behavior expected for Foucault pendulums. Otherwise φ repeatedly increases and decreases, which is the behavior of pendulums describing Lissajous figures. The vertical component of angular momentum is also calculated analytically.

  6. Single particle calculations for a Woods-Saxon potential with triaxial deformations, and large Cartesian oscillator basis (TRIAXIAL 2014, Third version of the code Triaxial)

    NASA Astrophysics Data System (ADS)

    Mohammed-Azizi, B.; Medjadi, D. E.

    2014-11-01

    , WINDOWS 7, LINUX. RAM: 256 Mb (depending on nmax). Swap file: 4Gb (depending on nmax) Classification: 17.7. Does the new version supersede the previous version?: Yes Catalogue identifier of previous version: ADSK_v2_0 Journal reference of previous version: Comput. Phys. Comm. 176 (2007) 634 Nature of problem: The Single particle energies and the single particle wave functions are calculated from one-body Hamiltonian including a central field of Woods-Saxon type, a spin-orbit interaction, and the Coulomb potential for the protons. We consider only ellipsoidal (triaxial) shapes. The deformation of the nuclear shape is fixed by the usual Bohr parameters (β,γ). Solution method: The representative matrix of the Hamiltonian is built by means of the Cartesian basis of the anisotropic harmonic oscillator, and then diagonalized by a set of subroutines of the EISPACK library. Two quadrature methods of Gauss are employed to calculate respectively the integrals of the matrix elements of the Hamiltonian, and the integral defining the Coulomb potential. Two quantum numbers are conserved: the parity and the signature. Due to the Kramers degeneracy, only positive signature is considered. Therefore, calculations are made for positive and negative parity separately (with positive signature only). Reasons for new version: Now, there are several ways to obtain the eigenvalues and the eigenfunctions. The eigenvalues can be obtained from the subroutine ‘eigvals’ or from the array ‘energies’ or also from the formatted files ‘valuu.dat’, ‘eigenvalo.dat’, ‘eigenva.dat’ or better from the unformatted file ‘eigenvaunf.dat’. The eigenfunctions can be obtained straightforwardly in configuration space from the subroutine ‘eigfunc’ or by their components on the oscillator basis from the subroutine ‘compnts’. The latter are also recorded on a formatted file ‘componento.dat’ or on an unformatted file ‘componentounf.dat’. Summary of revisions: This version is

  7. Single particle calculations for a Woods-Saxon potential with triaxial deformations, and large Cartesian oscillator basis (TRIAXIAL 2014, Third version of the code Triaxial)

    NASA Astrophysics Data System (ADS)

    Mohammed-Azizi, B.; Medjadi, D. E.

    2014-11-01

    , WINDOWS 7, LINUX. RAM: 256 Mb (depending on nmax). Swap file: 4Gb (depending on nmax) Classification: 17.7. Does the new version supersede the previous version?: Yes Catalogue identifier of previous version: ADSK_v2_0 Journal reference of previous version: Comput. Phys. Comm. 176 (2007) 634 Nature of problem: The Single particle energies and the single particle wave functions are calculated from one-body Hamiltonian including a central field of Woods-Saxon type, a spin-orbit interaction, and the Coulomb potential for the protons. We consider only ellipsoidal (triaxial) shapes. The deformation of the nuclear shape is fixed by the usual Bohr parameters (β,γ). Solution method: The representative matrix of the Hamiltonian is built by means of the Cartesian basis of the anisotropic harmonic oscillator, and then diagonalized by a set of subroutines of the EISPACK library. Two quadrature methods of Gauss are employed to calculate respectively the integrals of the matrix elements of the Hamiltonian, and the integral defining the Coulomb potential. Two quantum numbers are conserved: the parity and the signature. Due to the Kramers degeneracy, only positive signature is considered. Therefore, calculations are made for positive and negative parity separately (with positive signature only). Reasons for new version: Now, there are several ways to obtain the eigenvalues and the eigenfunctions. The eigenvalues can be obtained from the subroutine ‘eigvals’ or from the array ‘energies’ or also from the formatted files ‘valuu.dat’, ‘eigenvalo.dat’, ‘eigenva.dat’ or better from the unformatted file ‘eigenvaunf.dat’. The eigenfunctions can be obtained straightforwardly in configuration space from the subroutine ‘eigfunc’ or by their components on the oscillator basis from the subroutine ‘compnts’. The latter are also recorded on a formatted file ‘componento.dat’ or on an unformatted file ‘componentounf.dat’. Summary of revisions: This version is

  8. A Foucault's pendulum design

    NASA Astrophysics Data System (ADS)

    Salva, Horacio R.; Benavides, Rubén E.; Perez, Julio C.; Cuscueta, Diego J.

    2010-11-01

    In this article we explain our design and their performance, of a Foucault pendulum capable of continuous operation with a following system of the oscillation plane. We have built two pendulums, one of 2.835 m length and other of 4.975 m length. The oscillation amplitudes in either case were 1.8 and 1 deg, respectively. In our latitude the precession speed (9.89 deg/h counterclockwise) can be measured within 0.5 and 0.2 deg/h. The arrangement detected some earthquakes of medium intensity that took place as far as 765 km.

  9. A New Model of the Foucault Pendulum.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1979-01-01

    Describes an elastic Foucault pendulum designed to demonstrate how the rotation of the plane of oscillation depends on geographical latitude, and shows that this rotation vanishes at the equator. (GA)

  10. Single Particle Difraction at FLASH

    SciTech Connect

    Bogan, M.; Boutet, S.; Starodub, Dmitri; Decorwin-Martin, Philippe; Chapman, H.; Bajt, S.; Schulz, J.; Hajdu, Janos; Seibert, M.M.; Iwan, Bianca; Timneanu, Nicusor; Marchesini, Stefano; Barty, Anton; Benner, W.Henry; Frank, Matthias; Hau-Riege, Stefan P.; Woods, Bruce; Rohner, Urs; /Tofwerk AG, Thun

    2010-06-11

    Single-pulse coherent diffraction patterns have been collected from randomly injected single particles with a soft X-ray free-electron laser (FEL). The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of the object before that object turns into a plasma and explodes. A diffraction pattern of a single particle will only be recorded when the particle arrival into the FEL interaction region coincides with FEL pulse arrival and detector integration. The properties of the experimental apparatus coinciding with these three events set the data acquisition rate. For our single particle FLASH diffraction imaging experiments: (1) an aerodynamic lens stack prepared a particle beam that consisted of particles moving at 150-200 m/s positioned randomly in space and time, (2) the 10 fs long FEL pulses were delivered at a fixed rate, and (3) the detector was set to integrate and readout once every two seconds. The effect of these experimental parameters on the rate of data acquisition using randomly injected particles will be discussed. Overall, the ultrashort FEL pulses do not set the limit of the data acquisition, more important is the effective interaction time of the particle crossing the FEL focus, the pulse sequence structure and the detector readout rate. Example diffraction patterns of randomly injected ellipsoidal iron oxide nanoparticles in different orientations are presented. This is the first single particle diffraction data set of identical particles in different orientations collected on a shot-to-shot basis. This data set will be used to test algorithms for recovering 3D structure from single particle diffraction.

  11. Foucault and physiotherapy.

    PubMed

    Nicholls, David A

    2012-08-01

    For nearly 40 years, researchers have been coming to terms with the impact of Michel Foucault's philosophical work. In fields as diverse as medical sociology, health policy, architecture, urban geography, history, and sport, scholars have made use of Foucault's notions of discourse, knowledge, truth, and power. With a few exceptions, however, Foucault's writings have yet to permeate physiotherapy. Foucault's ideas represent powerful, and highly useful analytical strategies for analyzing our past, present, and future, and his writings provide us with a set of conceptual, methodological, and philosophical approaches to help us unpack the cultural, historical, and social context in which we operate as a profession. In this paper, I attempt to introduce the reader to some of Foucault's radical ideas and show how these might be applied to physiotherapy practice. Drawing on Foucault's writings on the functions of discourse to illustrate how something as benign as a physiotherapist's treatment bed can be understood as something more than a piece of necessary medical technology, I show that by approaching seemingly obvious, everyday objects, practices, systems, and structures, we can learn much about physiotherapy's past, present, and future and apply this knowledge to think in new ways about the profession. PMID:22765215

  12. {Lambda} single-particle energies

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.; Sami, M.

    1995-08-01

    We are continuing our work on the {Lambda} hyperon single-particle (s.p.) energies and their interpretation in terms of the basic {Lambda}-nuclear interactions. In particular we are interpreting the results obtained by S.C. Pieper, A. Usmani and Q.N. Usmani. We obtain about 30 MeV for the repulsive contribution of the three-body {Lambda}NN forces in nuclear matter. We are able to exclude purely {open_quotes}dispersive{close_quotes} {Lambda}NN forces. We are investigating the mix of dispersive and two-pion-exchange {Lambda}NN forces which provide a fit to the s.p. data. For interactions, which provide a fit to the s.p. data, the {Lambda} binding energy as a function of the nuclear matter density shows characteristic saturation features with a maximum at a density not very different from that of normal nuclear matter. We obtain a more precise measure of the space-exchange part of the {Lambda}-nuclear force than was previously available, corresponding to an exchange parameter {approx_equal} 0.32. The space-exchange force is rather directly related to the effective mass of a {Lambda} in the nuclear medium and turns out to be about 70% of its free mass. As a result, we also obtain a much better value for the p-state {Lambda}-nucleus potential which is about 40% of the s-state potential. The A binding to nuclear matter is determined to be {approx_equal} 28 MeV.

  13. Twin-Foucault imaging method

    NASA Astrophysics Data System (ADS)

    Harada, Ken

    2012-02-01

    A method of Lorentz electron microscopy, which enables observation two Foucault images simultaneously by using an electron biprism instead of an objective aperture, was developed. The electron biprism is installed between two electron beams deflected by 180° magnetic domains. Potential applied to the biprism deflects the two electron beams further, and two Foucault images with reversed contrast are then obtained in one visual field. The twin Foucault images are able to extract the magnetic domain structures and to reconstruct an ordinary electron micrograph. The developed Foucault method was demonstrated with a 180° domain structure of manganite La0.825Sr0.175MnO3.

  14. Foucault pendulum and sub-Riemannian geometry

    NASA Astrophysics Data System (ADS)

    Anzaldo-Meneses, A.; Monroy-Pérez, F.

    2010-08-01

    The well known Foucault nonsymmetrical pendulum is studied as a problem of sub-Riemannian geometry on nilpotent Lie groups. It is shown that in a rotating frame a sub-Riemannian structure can be naturally introduced. For small oscillations, three dimensional horizontal trajectories are computed and displayed in detail. The fiber bundle structure is explicitly shown. The underlying Lie structure is described together with the corresponding holonomy group, which turns out to be given by the center of the Heisenberg group. Other related physical problems that can be treated in a similar way are also mentioned.

  15. Foucault pendulum through basic geometry

    NASA Astrophysics Data System (ADS)

    von Bergmann, Jens; von Bergmann, HsingChi

    2007-10-01

    We provide a thorough explanation of the Foucault pendulum that utilizes its underlying geometry on a level suitable for science students not necessarily familiar with calculus. We also explain how the geometrically understood Foucault pendulum can serve as a prototype for more advanced phenomena in physics known as Berry's phase or geometric phases.

  16. School Foucault pendulum

    NASA Astrophysics Data System (ADS)

    Lacsny, Boris; Štubna, Igor; Teleki, Aba

    2014-11-01

    A Foucault pendulum was assembled for a university/high-school physics course. The pendulum is 2.85 m long and the mass of the bob is 4.70 kg. A new technique based on the spark burned points on a sheet of paper was used to register the pendulum’s motion. A Ruhmkorff induction coil was used as a high-voltage source. Plots of the elliptical trajectories (except the first trajectory, which is a straight line) can be created and the angles between the major axes of the ellipses can be determined after assigning the coordinates to the burned points.

  17. Single particle dynamics in circular accelerators

    SciTech Connect

    Ruth, R.D.

    1986-10-01

    The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

  18. The domestication of Foucault

    PubMed Central

    Goddard, Roy

    2014-01-01

    Though Foucault was intrigued by the possibilities of radical social transformation, he resolutely resisted the idea that such transformation could escape the effects of power and expressed caution when it came to the question of revolution. In this article we argue that in one particularly influential line of development of Foucault’s work his exemplary caution has been exaggerated in a way that weakens the political aspirations of post-Foucaldian scholarship. The site of this reduction is a complex debate over the role of normativity in Foucaldian research, where it has been claimed that Foucault’s genealogical approach is unable to answer the question ‘Why fight?’ The terms of this debate (on the neo-Foucaldian side) are limited by a dominant though selective interpretation of Foucault’s analytics of power, where power is understood primarily in terms of government, rather than struggle. In response we suggest that if we reconfigure power-as-government to power-as-war, this adjusts the central concern. ‘Why fight?’ becomes replaced by the more immediate question, ‘How fight?’ Without denying the obvious benefits of cautious scholarly work, we argue that a reconfiguration of Foucault’s analytics of power might help Foucaldian research to transcend the self-imposed ethic of political quietism that currently dominates the field. PMID:26273130

  19. Microorganism characterization by single particle mass spectrometry.

    PubMed

    Russell, Scott C

    2009-01-01

    In recent years a major effort by several groups has been undertaken to identify bacteria by mass spectrometry at the single cell level. The intent of this review is to highlight the recent progress made in the application of single particle mass spectrometry to the analysis of microorganisms. A large portion of the review highlights improvements in the ionization and mass analysis of bio-aerosols, or particles that contain biologically relevant molecules such as peptides or proteins. While these are not direct applications to bacteria, the results have been central to a progression toward single cell mass spectrometry. Developments in single particle matrix-assisted laser desorption/ionization (MALDI) are summarized. Recent applications of aerosol laser desorption/ionization (LDI) to the analysis of single microorganisms are highlighted. Successful applications of off-line and on-the-fly aerosol MALDI to microorganism detection are discussed. Limitations to current approaches and necessary future achievements are also addressed. PMID:18949817

  20. Gaussian beam photothermal single particle microscopy.

    PubMed

    Selmke, Markus; Braun, Marco; Cichos, Frank

    2012-10-01

    We explore the intuitive lensing picture of laser-heated nanoparticles occurring in single particle photothermal (PT) microscopy. The effective focal length of the thermal lens (TL) is derived from a ray-optics treatment and used to transform the probing focused Gaussian beam with ABCD Gaussian matrix optics. The relative PT signal is obtained from the relative beam-waist change far from the TL. The analytical expression is semiquantitative, capable of describing the entire phenomenology of single particle PT microscopy, and shows that the signal is the product of the point-spread functions of the involved lasers times a linear function of the axial coordinate. The presented particularly simple and intuitive Gaussian beam lensing picture compares favorably to the experimental results for 60 nm gold nanoparticles and provides the prescription for optimum setup calibration. PMID:23201674

  1. Single particle excitations in itinerant antiferromagnets

    SciTech Connect

    Brenig, W.; Kampf, A.P.

    1994-04-01

    The authors present a self-consistent strong coupling scheme to evaluate the single-particle Green`s function for the two dimensional Hubbard model in the spin-density-wave state. The authors analyze the single quasihole properties including its dispersion and its spectral weight factor. Significant incoherent contributions to the spectral function are found resulting from multi spin wave processes in accordance with similar results for the t-J model and small Hubbard clusters.

  2. Efficiency of single-particle engines

    NASA Astrophysics Data System (ADS)

    Proesmans, Karel; Driesen, Cedric; Cleuren, Bart; Van den Broeck, Christian

    2015-09-01

    We study the efficiency of a single-particle Szilard and Carnot engine. Within a first order correction to the quasistatic limit, the work distribution is found to be Gaussian and the correction factor to average work and efficiency only depends on the piston speed. The stochastic efficiency is studied for both models and the recent findings on efficiency fluctuations are confirmed numerically. Special features are revealed in the zero-temperature limit.

  3. Efficiency of single-particle engines.

    PubMed

    Proesmans, Karel; Driesen, Cedric; Cleuren, Bart; Van den Broeck, Christian

    2015-09-01

    We study the efficiency of a single-particle Szilard and Carnot engine. Within a first order correction to the quasistatic limit, the work distribution is found to be Gaussian and the correction factor to average work and efficiency only depends on the piston speed. The stochastic efficiency is studied for both models and the recent findings on efficiency fluctuations are confirmed numerically. Special features are revealed in the zero-temperature limit. PMID:26465424

  4. Carnot process with a single particle.

    PubMed

    Hoppenau, J; Niemann, M; Engel, A

    2013-06-01

    We determine the statistics of work in isothermal volume changes of a classical ideal gas consisting of a single particle. Combining our results with the findings of Lua and Grosberg [J. Chem. Phys. B 109, 6805 (2005)] on adiabatic expansions and compressions we then analyze the joint probability distribution of heat and work for a microscopic, nonequilibrium Carnot cycle. In the quasistatic limit we recover Carnot efficiency, however, combined with nontrivial distributions of work and heat. With increasing piston speed the efficiency decreases. The efficiency at maximum power stays within recently derived bounds. PMID:23848647

  5. Carnot process with a single particle

    NASA Astrophysics Data System (ADS)

    Hoppenau, J.; Niemann, M.; Engel, A.

    2013-06-01

    We determine the statistics of work in isothermal volume changes of a classical ideal gas consisting of a single particle. Combining our results with the findings of Lua and Grosberg [J. Chem. Phys. BJPCBFK1520-610610.1021/jp0455428 109, 6805 (2005)] on adiabatic expansions and compressions we then analyze the joint probability distribution of heat and work for a microscopic, nonequilibrium Carnot cycle. In the quasistatic limit we recover Carnot efficiency, however, combined with nontrivial distributions of work and heat. With increasing piston speed the efficiency decreases. The efficiency at maximum power stays within recently derived bounds.

  6. Photothermal single particle Rutherford scattering microscopy.

    PubMed

    Selmke, Markus; Cichos, Frank

    2013-03-01

    We demonstrate that the quantum-mechanical description of Rutherford scattering has a photonic counterpart in a new form of single particle photothermal microscopy. Using a split detector we provide experimental evidence that photons are deflected by a photothermal potential that is created by a local refractive index change around a heated nanoparticle. The deflection experienced is shown to be the analog to the deflection of a massive particle wave packet in unscreened spinless Coulomb scattering. The experimentally found focal detection geometry reveals a lateral split feature which will allow new correlation-based velocimetry experiments of absorbing particles with ultrahigh sensitivity. PMID:23521256

  7. Apparent subdiffusion inherent to single particle tracking.

    PubMed Central

    Martin, Douglas S; Forstner, Martin B; Käs, Josef A

    2002-01-01

    Subdiffusion and its causes in both in vivo and in vitro lipid membranes have become the focus of recent research. We report apparent subdiffusion, observed via single particle tracking (SPT), in a homogeneous system that only allows normal diffusion (a DMPC monolayer in the fluid state). The apparent subdiffusion arises from slight errors in finding the actual particle position due to noise inherent in all experimental SPT systems. A model is presented that corrects this artifact, and predicts the time scales after which the effect becomes negligible. The techniques and results presented in this paper should be of use in all SPT experiments studying normal and anomalous diffusion. PMID:12324428

  8. Apparent subdiffusion inherent to single particle tracking.

    PubMed

    Martin, Douglas S; Forstner, Martin B; Käs, Josef A

    2002-10-01

    Subdiffusion and its causes in both in vivo and in vitro lipid membranes have become the focus of recent research. We report apparent subdiffusion, observed via single particle tracking (SPT), in a homogeneous system that only allows normal diffusion (a DMPC monolayer in the fluid state). The apparent subdiffusion arises from slight errors in finding the actual particle position due to noise inherent in all experimental SPT systems. A model is presented that corrects this artifact, and predicts the time scales after which the effect becomes negligible. The techniques and results presented in this paper should be of use in all SPT experiments studying normal and anomalous diffusion. PMID:12324428

  9. Modeling positronium beyond the single particle approximation

    NASA Astrophysics Data System (ADS)

    Zubiaga, A.; Ervasti, M. M.; Makkonen, I.; Harju, A.; Tuomisto, F.; Puska, M. J.

    2016-03-01

    Understanding the properties of the positronium atom in matter is of interest for the interpretation of positron annihilation experiments. This technique has a unique capability for the investigation of nanometer sized voids and pores in soft molecular materials (polymers, liquids or biostructures) and porous materials. However, detailed interpretations of the experimental data rely on modeling of the annihilation properties of positronium in the host material. New applications of the technique are being developed but the computational models still are based on single particle approaches and there is no way to address the influence of the electronic properties of the host material. In this work we discuss new directions of research.

  10. Foucault's pendulum, a classical analog for the electron spin state

    NASA Astrophysics Data System (ADS)

    Linck, Rebecca A.

    Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  11. Single Particle Tomography in EMAN2

    PubMed Central

    Galaz-Montoya, Jesús G.; Flanagan, John; Schmid, Michael F.; Ludtke, Steven J.

    2015-01-01

    Single particle tomography (SPT or subtomogram averaging) offers a powerful alternative to traditional 2-D single particle reconstruction for studying conformationally or compositionally heterogeneous macromolecules. It can also provide direct observation (without labeling or staining) of complexes inside cells at nanometer resolution. The development of computational methods and tools for SPT remains an area of active research. Here we present the EMAN2.1 SPT toolbox, which offers a full SPT processing pipeline, from particle picking to post-alignment analysis of subtomogram averages, automating most steps. Different algorithm combinations can be applied at each step, providing versatility and allowing for procedural cross-testing and specimen-specific strategies. Alignment methods include all-vs-all, binary tree, iterative single-model refinement, multiple-model refinement, and self-symmetry alignment. An efficient angular search, Graphic Processing Unit (GPU) acceleration and both threaded and distributed parallelism are provided to speed up processing. Finally, automated simulations, per particle reconstruction of subtiltseries, and per-particle Contrast Transfer Function (CTF) correction have been implemented. Processing examples using both real and simulated data are shown for several structures. PMID:25956334

  12. Single Particle States in ^56Ni

    NASA Astrophysics Data System (ADS)

    Sanetullaev, Alisher; Lynch, W. G.; Tsang, M. B.; Bazin, D.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Lee, Jenny; Rogers, A. M.; Signoracci, A.; Sun, Z. Y.; Youngs, M.; Famiano, M.; Hudan, S.; O'Malley, P.; Peters, W. A.; Schmitt, K.; Shapira, D.; Charity, R. J.; Sobotka, L. G.

    2010-11-01

    Neutron spectroscopic factor of ^56Ni using (p, d) neutron transfer reaction has been measured using 37 MeV/u ^56Ni beam in inverse kinematics. The measurement was performed at NSCL using the high resolution silicon array, HiRA, to detect the deuterons in coincidence with the recoil residues detected in the S800 spectrometer. To test if ^56Ni is a good core, the most direct way is to measure the single particle nature of the neutrons or protons in the f7/2 orbits. Direct measurements of the spectroscopic factors of the neutron hole state in ^56Ni using the pickup (p,d) reaction will determine if the neutron f7/2 orbit is indeed a closed shell. In present work, preliminary experimental results will be presented.

  13. Quantification of aerosol chemical composition using continuous single particle measurements

    NASA Astrophysics Data System (ADS)

    Jeong, C.-H.; McGuire, M. L.; Godri, K. J.; Slowik, J. G.; Rehbein, P. J. G.; Evans, G. J.

    2011-07-01

    Mass concentrations of sulphate, nitrate, ammonium, organic carbon (OC), elemental carbon (EC) were determined from real time single particle data in the size range 0.1-3.0 μm measured by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) at urban and rural sites in Canada. To quantify chemical species within individual particles measured by an ATOFMS, ion peak intensity of m/z -97 for sulphate, -62 for nitrate, +18 for ammonium, +43 for OC, and +36 for EC were scaled using the number and size distribution data by an Aerodynamic Particle Sizer (APS) and a Fast Mobility Particle Sizer (FMPS). Hourly quantified chemical species from ATOFMS single-particle analysis were compared with collocated fine particulate matter (aerodynamic diameter < 2.5 μm, PM2.5) chemical composition measurements by an Aerosol Mass Spectrometer (AMS) at a rural site, a Gas-Particle Ion Chromatograph (GPIC) at an urban site, and a Sunset Lab field OCEC analyzer at both sites. The highest correlation was found for nitrate, with correlation coefficients (Pearson r) of 0.89 (ATOFMS vs. GPIC) and 0.85 (ATOFMS vs. AMS). ATOFMS mass calibration factors, determined for the urban site, were used to calculate mass concentrations of the major PM2.5 chemical components at the rural site near the US border in southern Ontario. Mass reconstruction using the ATOFMS mass calibration factors agreed very well with the PM2.5 mass concentrations measured by a Tapered Element Oscillating Microbalance (TEOM, r = 0.86) at the urban site and a light scattering monitor (DustTrak, r = 0.87) at the rural site. In the urban area nitrate was the largest contributor to PM2.5 mass in the winter, while organics and sulphate contributed ~64 % of the summer PM2.5 in the rural area, suggesting a strong influence of regional/trans-boundary pollution. The mass concentrations of five major species in ten size-resolved particle-types and aerosol acidity of each particle-type were determined for the rural site. On a mass basis

  14. Three-dimensional single particle tracking in dense dust clouds by stereoscopy of fluorescent particles

    SciTech Connect

    Himpel, Michael; Killer, Carsten; Buttenschoen, Birger; Melzer, Andre

    2012-12-15

    In dense dust clouds of a dusty plasma single particle trajectories are impossible to follow due to occlusion of particles and ambiguities in particle correspondences. By stereoscopic imaging of fluorescent tracer particles, we were able to reconstruct 3D single particle trajectories within dense dust clouds. Several measurements are shown that justify to regard the tracer particles as suitable representatives for the whole dust system. A first analysis of dust density waves in dense clouds already shows that these waves exhibit three-dimensional dynamics at larger wave amplitudes that cannot be resolved by 2D imaging techniques: a broad velocity distribution perpendicular to the oscillation plane due to dust-dust collisions is seen, while the velocity distribution in the oscillation direction is bimodal and shifted due to the bulk wave propagation.

  15. Foucault's Pendulum, Analog for an Electron Spin State

    NASA Astrophysics Data System (ADS)

    Linck, Rebecca

    2012-11-01

    The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  16. Plasmonic polymers unraveled through single particle spectroscopy.

    PubMed

    Slaughter, Liane S; Wang, Lin-Yung; Willingham, Britain A; Olson, Jana M; Swanglap, Pattanawit; Dominguez-Medina, Sergio; Link, Stephan

    2014-10-01

    Plasmonic polymers are quasi one-dimensional assemblies of nanoparticles whose optical responses are governed by near-field coupling of localized surface plasmons. Through single particle extinction spectroscopy correlated with electron microscopy, we reveal the effect of the composition of the repeat unit, the chain length, and extent of disorder on the energies, intensities, and line shapes of the collective resonances of individual plasmonic polymers constructed from three different sizes of gold nanoparticles. Our combined experimental and theoretical analysis focuses on the superradiant plasmon mode, which results from the most attractive interactions along the nanoparticle chain and yields the lowest energy resonance in the spectrum. This superradiant mode redshifts with increasing chain length until an infinite chain limit, where additional increases in chain length cause negligible change in the energy of the superradiant mode. We find that, among plasmonic polymers of equal width comprising nanoparticles with different sizes, the onset of the infinite chain limit and its associated energy are dictated by the number of repeat units and not the overall length of the polymer. The intensities and linewidths of the superradiant mode relative to higher energy resonances, however, differ as the size and number of nanoparticles are varied in the plasmonic polymers studied here. These findings provide general guidelines for engineering the energies, intensities, and line shapes of the collective optical response of plasmonic polymers constructed from nanoparticles with sizes ranging from a few tens to one hundred nanometers. PMID:25155111

  17. Single-particle stochastic heat engine.

    PubMed

    Rana, Shubhashis; Pal, P S; Saha, Arnab; Jayannavar, A M

    2014-10-01

    We have performed an extensive analysis of a single-particle stochastic heat engine constructed by manipulating a Brownian particle in a time-dependent harmonic potential. The cycle consists of two isothermal steps at different temperatures and two adiabatic steps similar to that of a Carnot engine. The engine shows qualitative differences in inertial and overdamped regimes. All the thermodynamic quantities, including efficiency, exhibit strong fluctuations in a time periodic steady state. The fluctuations of stochastic efficiency dominate over the mean values even in the quasistatic regime. Interestingly, our system acts as an engine provided the temperature difference between the two reservoirs is greater than a finite critical value which in turn depends on the cycle time and other system parameters. This is supported by our analytical results carried out in the quasistatic regime. Our system works more reliably as an engine for large cycle times. By studying various model systems, we observe that the operational characteristics are model dependent. Our results clearly rule out any universal relation between efficiency at maximum power and temperature of the baths. We have also verified fluctuation relations for heat engines in time periodic steady state. PMID:25375477

  18. Foucault, Biopolitics and the Birth of Neoliberalism

    ERIC Educational Resources Information Center

    Peters, Michael A.

    2007-01-01

    In his governmentality studies in the late 1970s Foucault held a course at the College de France on the major forms of neoliberalism, examining the three theoretical schools of German ordoliberalism, the Austrian school characterized by Hayek, and American neoliberalism in the form of the Chicago school. Among Foucault's great insights in his work…

  19. Leon Foucault: His Life, Times and Achievements

    ERIC Educational Resources Information Center

    Aczel, Amir D.

    2004-01-01

    Leon Foucault's dramatic demonstration of the rotation of the Earth using a freely-rotating pendulum in 1850 shocked the world of science. Scientists were stunned that such a simple proof of our planet's rotation had to wait so long to be developed. Foucault's public demonstration, which was repeated at many locations around the world, put an end…

  20. Plasmonic polymers unraveled through single particle spectroscopy

    NASA Astrophysics Data System (ADS)

    Slaughter, Liane S.; Wang, Lin-Yung; Willingham, Britain A.; Olson, Jana M.; Swanglap, Pattanawit; Dominguez-Medina, Sergio; Link, Stephan

    2014-09-01

    Plasmonic polymers are quasi one-dimensional assemblies of nanoparticles whose optical responses are governed by near-field coupling of localized surface plasmons. Through single particle extinction spectroscopy correlated with electron microscopy, we reveal the effect of the composition of the repeat unit, the chain length, and extent of disorder on the energies, intensities, and line shapes of the collective resonances of individual plasmonic polymers constructed from three different sizes of gold nanoparticles. Our combined experimental and theoretical analysis focuses on the superradiant plasmon mode, which results from the most attractive interactions along the nanoparticle chain and yields the lowest energy resonance in the spectrum. This superradiant mode redshifts with increasing chain length until an infinite chain limit, where additional increases in chain length cause negligible change in the energy of the superradiant mode. We find that, among plasmonic polymers of equal width comprising nanoparticles with different sizes, the onset of the infinite chain limit and its associated energy are dictated by the number of repeat units and not the overall length of the polymer. The intensities and linewidths of the superradiant mode relative to higher energy resonances, however, differ as the size and number of nanoparticles are varied in the plasmonic polymers studied here. These findings provide general guidelines for engineering the energies, intensities, and line shapes of the collective optical response of plasmonic polymers constructed from nanoparticles with sizes ranging from a few tens to one hundred nanometers.Plasmonic polymers are quasi one-dimensional assemblies of nanoparticles whose optical responses are governed by near-field coupling of localized surface plasmons. Through single particle extinction spectroscopy correlated with electron microscopy, we reveal the effect of the composition of the repeat unit, the chain length, and extent of

  1. Single particle states in the heaviest elements

    SciTech Connect

    Ahmad, I.; Chasman, R.R.

    1995-08-01

    The search for superheavy elements was a major theme of nuclear structure research for the past twenty years. Theoretical predictions of the stability of superheavy elements depend crucially on the single-particle energy level spacings in the vicinity of 114 protons and 184 neutrons. The approach that we are taking is to learn as much as possible about these levels from spectroscopic studies of nuclides in the A = 250 region. This is possible because there are members of the relevant spherical multiplets that drop rapidly in energy with increasing deformation, and are fairly close to ground in the strongly deformed nuclides near A = 250. The orbitals that are important for fixing the shell corrections near N = 184 are the h{sub 11/2}, j{sub 13/2} and k{sub 17/2} spherical states. For each of these spherical orbitals, there is a corresponding deformed orbital whose energy in the A = 250 region is quite sensitive to one of these spherical states, e. g. the 1/2-[761] orbital was already identified in {sup 251}Cf is quite sensitive to the spherical j{sub 13/2} orbital. The position of the 1/2+[880] deformed orbital is very sensitive to the k{sub 17/2} spherical state. According to our calculations, this state should be found at {approximately}1500 KeV in {sup 251}Cf and should be populated in a one-nucleon transfer reaction using an ({alpha},{sup 3}He) reaction. We calculated signatures for the low-lying states in {sup 251}Cf and the calculated energies and signatures are in good agreement with the experimentally observed (d,p) spectrum. We expect to see the high-j states in an ({alpha},{sup 3}He) study. Our analysis of low-lying states in {sup 251}Cf was published. The ({alpha},{sup 3}He) experiment was approved, and is waiting on the preparation of a target.

  2. Microprocessor-based single particle calibration of scintillation counter

    NASA Technical Reports Server (NTRS)

    Mazumdar, G. K. D.; Pathak, K. M.

    1985-01-01

    A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

  3. A Short Foucault Pendulum for Corridor Display.

    ERIC Educational Resources Information Center

    Leonard, Byron E.

    1981-01-01

    Describes the construction and operation of a short Foucault pendulum, which indicates earth's rotation with less than 2 percent error. The pendulum is suitable for display either in a classroom or hallway. (SK)

  4. 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.

  5. The Humanist Turn in Foucault's Rhetoric of Inquiry.

    ERIC Educational Resources Information Center

    Blair, Carole; Cooper, Martha

    1987-01-01

    Discusses the relationship of Michel Foucault's work to the human perspective. Argues that Fisher is inaccurate in characterizing Foucault as an "anti-humanist." Claims that Foucault's concept of the "statement" and his method of critique turn the humanist perspective toward a liberating, activist form that allows for change within the status quo.…

  6. "Finding Foucault": Orders of Discourse and Cultures of the Self

    ERIC Educational Resources Information Center

    Besley, A. C.

    2015-01-01

    The idea of finding Foucault first looks at the many influences on Foucault, including his Nietzschean acclamations. It examines Foucault's critical history of thought, his work on the orders of discourse with his emphasis on being a pluralist: the problem he says that he has set himself is that of the individualization of discourses. Finally, it…

  7. Foucault and Marxism: Rewriting the Theory of Historical Materialism

    ERIC Educational Resources Information Center

    Olssen, Mark

    2004-01-01

    This article explores the relationship of Foucault to Marxism. Although he was often critical of Marxism, Foucault's own approach bears striking parallels to Marxism, as a form of method, as an account of history, and as an analysis of social structure. Like Marxism, Foucault represents social practices as transitory and all knowledge and…

  8. Foucault and the Turn to Narrative Therapy.

    ERIC Educational Resources Information Center

    Besley, A. C. (Tina)

    2002-01-01

    The pioneering authors of narrative therapy, White and Epston, state clearly that they have been influenced by the work of the French theorist Michel Foucault. This paper briefly outlines some features of narrative therapy, examines the Foucauldian themes in White and Epston's theory, and explores narrative therapy's poststructuralist challenge to…

  9. Jim Marshall: Foucault and Disciplining the Self

    ERIC Educational Resources Information Center

    Besley, A. C.

    2005-01-01

    This paper notes how Jim influenced my own use of Foucault and also focuses on two of James Marshall's New Zealand oriented texts. In the first, "Discipline and Punishment in New Zealand Education" (Marshall & Marshall, 1997) he provides a Foucauldian genealogy of New Zealand approaches to both punishment and discipline, in particular corporal…

  10. Foucault, Counselling and the Aesthetics of Existence

    ERIC Educational Resources Information Center

    Peters, Michael A.

    2005-01-01

    Michel Foucault was drawn late in life to study the "arts of the self" in Greco-Roman culture as a basis, following Nietzsche, for what he called an "aesthetics of existence." By this, he meant a set of creative and experimental processes and techniques by which an individual turns him- or herself into a work of art. For Nietzsche, it was above…

  11. Pushing the limits of the Foucault Test

    NASA Astrophysics Data System (ADS)

    Swanepoel, Johann

    2010-12-01

    The processes involved in the shaping and testing of two fast 20-inch diameter thin Pyrex mirrors are briefly described. Some improvements to extend the usefulness and accuracy of the age old Foucault knife-edge test, making use of affordable and easily available modern technology, are described in some detail.

  12. Foucault's Heterotopia and Children's Everyday Lives.

    ERIC Educational Resources Information Center

    McNamee, Sara

    2000-01-01

    Discusses Foucault's notion of "heterotopia"--real places but which exist unto themselves, such as a floating ship. Considers data on children's use of computer and video games to apply "heterotopia" to children's everyday social lives. Argues that childhood is subject to increasing boundaries, and that children create "other" spaces through…

  13. Praxis and Agency in Foucault's Historiography

    ERIC Educational Resources Information Center

    Fendler, Lynn

    2004-01-01

    This paper examines the consequences for agency that Foucault's historiographical approach constructs. The analysis begins by explaining the difference between "legislative history" and "exemplary history," drawing parallels to similar theoretical distinctions offered in the works of Max Weber, J.L. Austin, and Zygmunt Bauman. The analysis…

  14. "Safeguarding" Sports Coaching: Foucault, Genealogy and Critique

    ERIC Educational Resources Information Center

    Garratt, Dean; Piper, Heather; Taylor, Bill

    2013-01-01

    This paper offers a genealogical account of safeguarding in sport. Drawing specifically on Foucault's work, it examines the "politics of touch" in relation to the social and historical formation of child protection policy in sports coaching. While the analysis has some resonance with the context of coaching as a whole, for…

  15. Single particle density of trapped interacting quantum gases

    SciTech Connect

    Bala, Renu; Bosse, J.; Pathak, K. N.

    2015-05-15

    An expression for single particle density for trapped interacting gases has been obtained in first order of interaction using Green’s function method. Results are easily simplified for homogeneous quantum gases and are found to agree with famous results obtained by Huang-Yang-Luttinger and Lee-Yang.

  16. Single-particle spectroscopic factors for spherical nuclei

    SciTech Connect

    Gnezdilov, N. V.; Saperstein, E. E. Tolokonnikov, S. V.

    2015-01-15

    Within the self-consistent theory of finite Fermi systems, the total single-particle spectroscopic factors for seven doubly magic nuclei of {sup 40}Ca, {sup 48}Ca, {sup 56}Ni, {sup 78}Ni, {sup 100}Sn, {sup 132}Sn, and {sup 208}Pb and for the {sup 188–212}Pb chain of semimagic even lead isotopes are calculated by the energy-density-functional method implemented with a functional in the form proposed by Fayans and his coauthors. The spectroscopic factor is expressed in terms of the Z factor, which is the residue of the single-particle Green’s function at the single-particle pole. The total Z factor calculated in the present study involves both effects of coupling to phonons and the volume Z factor, which is due to the fact that the mass operator features an energy dependence not associated with surface phonons. The volume Z factor is on the same order of magnitude as the phonon-coupling contribution. The volume effect depends only slightly on the nuclear species and on the single-particle state λ. On the contrary, the phonon contribution to the total spectroscopic factor changes upon going over from one state to another and from one nuclear species to another.

  17. Single-particle spectroscopic factors for spherical nuclei

    NASA Astrophysics Data System (ADS)

    Gnezdilov, N. V.; Saperstein, E. E.; Tolokonnikov, S. V.

    2015-01-01

    Within the self-consistent theory of finite Fermi systems, the total single-particle spectroscopic factors for seven doubly magic nuclei of 40Ca, 48Ca, 56Ni, 78Ni, 100Sn, 132Sn, and 208Pb and for the 188-212Pb chain of semimagic even lead isotopes are calculated by the energy-density-functional method implemented with a functional in the form proposed by Fayans and his coauthors. The spectroscopic factor is expressed in terms of the Z factor, which is the residue of the single-particle Green's function at the single-particle pole. The total Z factor calculated in the present study involves both effects of coupling to phonons and the volume Z factor, which is due to the fact that the mass operator features an energy dependence not associated with surface phonons. The volume Z factor is on the same order of magnitude as the phonon-coupling contribution. The volume effect depends only slightly on the nuclear species and on the single-particle state λ. On the contrary, the phonon contribution to the total spectroscopic factor changes upon going over from one state to another and from one nuclear species to another.

  18. Calibration of single particle sizing velocimeters using photomask reticles

    NASA Technical Reports Server (NTRS)

    Hirleman, E. D.; Holve, D. J.; Hovenac, E. A.

    1988-01-01

    The development of photomask reticle calibration standards for single particle instruments is discussed. The calibration method studied involves the use of photomask reticles where the particle artifacts are actually disks of chrome thin film in the clear field reticles produced by photolithography and etching processes. Consideration is given to various aspects of theory, design, and performance.

  19. Single Particle Orientation and Rotational Tracking (SPORT) in biopysical studies

    SciTech Connect

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

    2013-08-02

    The single particle orientation and rotational tracking (SPORT) techniques have seen rapid development in the past 5 years. Recent technical advances have greatly expanded the applicability of SPORT in biophysical studies. In this feature article, we survey the current development of SPORT and discuss its potential applications in biophysics, including cellular membrane processes and intracellular transport.

  20. High resolution single particle refinement in EMAN2.1.

    PubMed

    Bell, James M; Chen, Muyuan; Baldwin, Philip R; Ludtke, Steven J

    2016-05-01

    EMAN2.1 is a complete image processing suite for quantitative analysis of grayscale images, with a primary focus on transmission electron microscopy, with complete workflows for performing high resolution single particle reconstruction, 2-D and 3-D heterogeneity analysis, random conical tilt reconstruction and subtomogram averaging, among other tasks. In this manuscript we provide the first detailed description of the high resolution single particle analysis pipeline and the philosophy behind its approach to the reconstruction problem. High resolution refinement is a fully automated process, and involves an advanced set of heuristics to select optimal algorithms for each specific refinement task. A gold standard FSC is produced automatically as part of refinement, providing a robust resolution estimate for the final map, and this is used to optimally filter the final CTF phase and amplitude corrected structure. Additional methods are in-place to reduce model bias during refinement, and to permit cross-validation using other computational methods. PMID:26931650

  1. Single particle electrochemical sensors and methods of utilization

    DOEpatents

    Schoeniger, Joseph; Flounders, Albert W.; Hughes, Robert C.; Ricco, Antonio J.; Wally, Karl; Kravitz, Stanley H.; Janek, Richard P.

    2006-04-04

    The present invention discloses an electrochemical device for detecting single particles, and methods for using such a device to achieve high sensitivity for detecting particles such as bacteria, viruses, aggregates, immuno-complexes, molecules, or ionic species. The device provides for affinity-based electrochemical detection of particles with single-particle sensitivity. The disclosed device and methods are based on microelectrodes with surface-attached, affinity ligands (e.g., antibodies, combinatorial peptides, glycolipids) that bind selectively to some target particle species. The electrodes electrolyze chemical species present in the particle-containing solution, and particle interaction with a sensor element modulates its electrolytic activity. The devices may be used individually, employed as sensors, used in arrays for a single specific type of particle or for a range of particle types, or configured into arrays of sensors having both these attributes.

  2. A Primer to Single-Particle Cryo-Electron Microscopy

    PubMed Central

    Cheng, Yifan; Grigorieff, Nikolaus; Penczek, Pawel A.; Walz, Thomas

    2015-01-01

    Summary Cryo-electron microscopy (cryo-EM) of single-particle specimens is used to determine the structure of proteins and macromolecular complexes without the need for crystals. Recent advances in detector technology and software algorithms now allow images of unprecedented quality to be recorded and structures to be determined at near-atomic resolution. However, compared with X-ray crystallography, cryo-EM is a young technique with distinct challenges. This primer explains the different steps and considerations involved in structure determination by single-particle cryo-EM to provide an overview for scientists wishing to understand more about this technique and the interpretation of data obtained with it, as well as a starting guide for new practitioners. PMID:25910204

  3. Optimal diffusion coefficient estimation in single-particle tracking

    PubMed Central

    Michalet, Xavier; Berglund, Andrew J.

    2016-01-01

    Single-particle tracking is increasingly used to extract quantitative parameters on single molecules and their environment, while advances in spatial and temporal resolution of tracking techniques inspire new questions and avenues of investigation. Correspondingly, sophisticated analytical methods are constantly developed to obtain more refined information from measured trajectories. Here we point out some fundamental limitations of these approaches due to the finite length of trajectories, the presence of localization error, and motion blur, focusing on the simplest motion regime of free diffusion in an isotropic medium (Brownian motion). We show that two recently proposed algorithms approach the theoretical limit of diffusion coefficient uncertainty. We discuss the practical performance of the algorithms as well as some important implications of these results for single-particle tracking. PMID:23005136

  4. Single-particle mechanism of magnetostriction in magnetoactive elastomers

    NASA Astrophysics Data System (ADS)

    Kalita, Viktor M.; Snarskii, Andrei A.; Zorinets, Denis; Shamonin, Mikhail

    2016-06-01

    Magnetoactive elastomers (MAEs) are composite materials comprised of micrometer-sized ferromagnetic particles in a nonmagnetic elastomer matrix. A single-particle mechanism of magnetostriction in MAEs, assuming the rotation of a soft magnetic, mechanically rigid particle with uniaxial magnetic anisotropy in magnetic fields is identified and considered theoretically within the framework of an alternative model. In this mechanism, the total magnetic anisotropy energy of the filling particles in the matrix is the sum over single particles. Matrix displacements in the vicinity of the particle and the resulting direction of the magnetization vector are calculated. The effect of matrix deformation is pronounced well if the magnetic anisotropy coefficient K is much larger than the shear modulus µ of the elastic matrix. The feasibility of the proposed magnetostriction mechanism in soft magnetoactive elastomers and gels is elucidated. The magnetic-field-induced internal stresses in the matrix lead to effects of magnetodeformation and may increase the elastic moduli of these composite materials.

  5. Single particle nanomechanics in operando batteries via lensless strain mapping.

    PubMed

    Ulvestad, Andrew; Singer, Andrej; Cho, Hyung-Man; Clark, Jesse N; Harder, Ross; Maser, Jorg; Meng, Ying Shirley; Shpyrko, Oleg G

    2014-09-10

    We reveal three-dimensional strain evolution in situ of a single LiNi0.5Mn1.5O4 nanoparticle in a coin cell battery under operando conditions during charge/discharge cycles with coherent X-ray diffractive imaging. We report direct observation of both stripe morphologies and coherency strain at the nanoscale. Our results suggest the critical size for stripe formation is 50 nm. Surprisingly, the single nanoparticle elastic energy landscape, which we map with femtojoule precision, depends on charge versus discharge, indicating hysteresis at the single particle level. This approach opens a powerful new avenue for studying battery nanomechanics, phase transformations, and capacity fade under operando conditions at the single particle level that will enable profound insight into the nanoscale mechanisms that govern electrochemical energy storage systems. PMID:25141157

  6. Stereoscopy of dust density waves under microgravity: Velocity distributions and phase-resolved single-particle analysis

    SciTech Connect

    Himpel, Michael Killer, Carsten; Melzer, André; Bockwoldt, Tim; Piel, Alexander; Ole Menzel, Kristoffer

    2014-03-15

    Experiments on dust-density waves have been performed in dusty plasmas under the microgravity conditions of parabolic flights. Three-dimensional measurements of a dust density wave on a single particle level are presented. The dust particles have been tracked for many oscillation periods. A Hilbert analysis is applied to obtain trajectory parameters such as oscillation amplitude and three-dimensional velocity amplitude. While the transverse motion is found to be thermal, the velocity distribution in wave propagation direction can be explained by harmonic oscillations with added Gaussian (thermal) noise. Additionally, it is shown that the wave properties can be reconstructed by means of a pseudo-stroboscopic approach. Finally, the energy dissipation mechanism from the kinetic oscillation energy to thermal motion is discussed and presented using phase-resolved analysis.

  7. Generalized single-particle cryo-EM--a historical perspective.

    PubMed

    Frank, Joachim

    2016-02-01

    This is a brief account of the earlier history of single-particle cryo-EM of biological molecules lacking internal symmetry, which goes back to the mid-seventies. The emphasis of this review is on the mathematical concepts and computational approaches. It is written as the field experiences a turning point in the wake of the introduction of digital cameras capable of single electron counting, and near-atomic resolution can be reached even for smaller molecules. PMID:26566976

  8. Cryptanalysis of quantum secret sharing with d -level single particles

    NASA Astrophysics Data System (ADS)

    Lin, Song; Guo, Gong-De; Xu, Yong-Zhen; Sun, Ying; Liu, Xiao-Fen

    2016-06-01

    In a recent paper [V. Karimipour and M. Asoudeh, Phys. Rev. A 92, 030301(R) (2015)], 10.1103/PhysRevA.92.030301, a multiparty quantum secret-sharing protocol based on d -level single particles was proposed. We discussed the security of this protocol and found that it is not secure for any one dishonest participant who can recover the secret without the aid of other participants.

  9. Spin resonance strength calculation through single particle tracking for RHIC

    SciTech Connect

    Luo, Y.; Dutheil, Y.; Huang, H.; Meot, F.; Ranjbar, V.

    2015-05-03

    The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with the code DEPOL, which numerically integrates through the ring based on an analytical approximate formula. In this article, we test a new way to calculate the spin resonance strengths by performing Fourier transformation to the actual transverse magnetic fields seen by a single particle traveling through the ring. Comparison of calculated spin resonance strengths is made between this method and DEPOL.

  10. Exploring dynamics in living cells by tracking single particles.

    PubMed

    Levi, Valeria; Gratton, Enrico

    2007-01-01

    In the last years, significant advances in microscopy techniques and the introduction of a novel technology to label living cells with genetically encoded fluorescent proteins revolutionized the field of Cell Biology. Our understanding on cell dynamics built from snapshots on fixed specimens has evolved thanks to our actual capability to monitor in real time the evolution of processes in living cells. Among these new tools, single particle tracking techniques were developed to observe and follow individual particles. Hence, we are starting to unravel the mechanisms driving the motion of a wide variety of cellular components ranging from organelles to protein molecules by following their way through the cell. In this review, we introduce the single particle tracking technology to new users. We briefly describe the instrumentation and explain some of the algorithms commonly used to locate and track particles. Also, we present some common tools used to analyze trajectories and illustrate with some examples the applications of single particle tracking to study dynamics in living cells. PMID:17703064

  11. Computer simulations of single particles in external electric fields.

    PubMed

    Zhou, Jiajia; Schmid, Friederike

    2015-09-14

    Applying electric fields is an attractive way to control and manipulate single particles or molecules, e.g., in lab-on-a-chip devices. However, the response of nanosize objects in electrolyte solution to external fields is far from trivial. It is the result of a variety of dynamical processes taking place in the ion cloud surrounding charged particles and in the bulk electrolyte, and it is governed by an intricate interplay of electrostatic and hydrodynamic interactions. Already systems composed of one single particle in electrolyte solution exhibit a complex dynamical behaviour. In this review, we discuss recent coarse-grained simulations that have been performed to obtain a molecular-level understanding of the dynamic and dielectric response of single particles and single macromolecules to external electric fields. We address both the response of charged particles to constant fields (DC fields), which can be characterized by an electrophoretic mobility, and the dielectric response of both uncharged and charged particles to alternating fields (AC fields), which is described by a complex polarizability. Furthermore, we give a brief survey of simulation algorithms and highlight some recent developments. PMID:26238433

  12. Seismic shear waves as Foucault pendulum

    NASA Astrophysics Data System (ADS)

    Snieder, Roel; Sens-Schönfelder, Christoph; Ruigrok, Elmer; Shiomi, Katsuhiko

    2016-03-01

    Earth's rotation causes splitting of normal modes. Wave fronts and rays are, however, not affected by Earth's rotation, as we show theoretically and with observations made with USArray. We derive that the Coriolis force causes a small transverse component for P waves and a small longitudinal component for S waves. More importantly, Earth's rotation leads to a slow rotation of the transverse polarization of S waves; during the propagation of S waves the particle motion behaves just like a Foucault pendulum. The polarization plane of shear waves counteracts Earth's rotation and rotates clockwise in the Northern Hemisphere. The rotation rate is independent of the wave frequency and is purely geometric, like the Berry phase. Using the polarization of ScS and ScS2 waves, we show that the Foucault-like rotation of the S wave polarization can be observed. This can affect the determination of source mechanisms and the interpretation of observed SKS splitting.

  13. Interplay between plasmon and single-particle excitations in a metal nanocluster.

    PubMed

    Ma, Jie; Wang, Zhi; Wang, Lin-Wang

    2015-01-01

    Plasmon-generated hot carriers are used in photovoltaic or photochemical applications. However, the interplays between the plasmon and single-particle excitations in nanosystems have not been theoretically addressed using ab initio methods. Here we show such interplays in a Ag55 nanocluster using real-time time-dependent density functional theory simulations. We find that the disappearance of the zero-frequency peak in the Fourier transform of the band-to-band transition coefficient is a hallmark of the plasmon. We show the importance of the d-states for hot-carrier generations. If the single-particle d-to-s excitations are resonant to the plasmon frequency, the majority of the plasmon energy will be converted into hot carriers, and the overall hot-carrier generation is enhanced by the plasmon; if such resonance does not exist, we observe an intriguing Rabi oscillation between the plasmon and hot carriers. Phonons play a minor role in plasmonic dynamics in such small systems. This study provides guidance on improving plasmonic applications. PMID:26673449

  14. Interplay between plasmon and single-particle excitations in a metal nanocluster

    DOE PAGESBeta

    Ma, Jie; Wang, Zhi; Wang, Lin-Wang

    2015-12-17

    Plasmon-generated hot carriers are used in photovoltaic or photochemical applications. However, the interplays between the plasmon and single-particle excitations in nanosystems have not been theoretically addressed using ab initio methods. Here we show such interplays in a Ag55 nanocluster using real-time time-dependent density functional theory simulations. We find that the disappearance of the zero-frequency peak in the Fourier transform of the band-to-band transition coefficient is a hallmark of the plasmon. We show the importance of the d-states for hot-carrier generations. If the single-particle d-to-s excitations are resonant to the plasmon frequency, the majority of the plasmon energy will be convertedmore » into hot carriers, and the overall hot-carrier generation is enhanced by the plasmon; if such resonance does not exist, we observe an intriguing Rabi oscillation between the plasmon and hot carriers. Phonons play a minor role in plasmonic dynamics in such small systems. Ultimately, this study provides guidance on improving plasmonic applications.« less

  15. Interplay between plasmon and single-particle excitations in a metal nanocluster

    PubMed Central

    Ma, Jie; Wang, Zhi; Wang, Lin-Wang

    2015-01-01

    Plasmon-generated hot carriers are used in photovoltaic or photochemical applications. However, the interplays between the plasmon and single-particle excitations in nanosystems have not been theoretically addressed using ab initio methods. Here we show such interplays in a Ag55 nanocluster using real-time time-dependent density functional theory simulations. We find that the disappearance of the zero-frequency peak in the Fourier transform of the band-to-band transition coefficient is a hallmark of the plasmon. We show the importance of the d-states for hot-carrier generations. If the single-particle d-to-s excitations are resonant to the plasmon frequency, the majority of the plasmon energy will be converted into hot carriers, and the overall hot-carrier generation is enhanced by the plasmon; if such resonance does not exist, we observe an intriguing Rabi oscillation between the plasmon and hot carriers. Phonons play a minor role in plasmonic dynamics in such small systems. This study provides guidance on improving plasmonic applications. PMID:26673449

  16. Interplay between plasmon and single-particle excitations in a metal nanocluster

    SciTech Connect

    Ma, Jie; Wang, Zhi; Wang, Lin-Wang

    2015-12-17

    Plasmon-generated hot carriers are used in photovoltaic or photochemical applications. However, the interplays between the plasmon and single-particle excitations in nanosystems have not been theoretically addressed using ab initio methods. Here we show such interplays in a Ag55 nanocluster using real-time time-dependent density functional theory simulations. We find that the disappearance of the zero-frequency peak in the Fourier transform of the band-to-band transition coefficient is a hallmark of the plasmon. We show the importance of the d-states for hot-carrier generations. If the single-particle d-to-s excitations are resonant to the plasmon frequency, the majority of the plasmon energy will be converted into hot carriers, and the overall hot-carrier generation is enhanced by the plasmon; if such resonance does not exist, we observe an intriguing Rabi oscillation between the plasmon and hot carriers. Phonons play a minor role in plasmonic dynamics in such small systems. Ultimately, this study provides guidance on improving plasmonic applications.

  17. New apparatus of single particle trap system for aerosol visualization

    NASA Astrophysics Data System (ADS)

    Higashi, Hidenori; Fujioka, Tomomi; Endo, Tetsuo; Kitayama, Chiho; Seto, Takafumi; Otani, Yoshio

    2014-08-01

    Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

  18. Nature of single-particle states in disordered graphene

    NASA Astrophysics Data System (ADS)

    Nag, Sabyasachi; Garg, Arti; Ramakrishnan, T. V.

    2016-06-01

    We analyze the nature of the single-particle states, away from the Dirac point in the presence of long-range charge impurities in a tight-binding model for electrons on a two-dimensional honeycomb lattice which is of direct relevance for graphene. For a disorder potential V (r ⃗) =V0exp(-| r ⃗-r⃗imp|2/ξ2) , we demonstrate that not only the Dirac state but all the single-particle states remain extended for weak-enough disorder. Based on our numerical calculations of inverse participation ratio, dc conductivity, diffusion coefficient, and the localization length from time evolution dynamics of the wave packet, we show that the threshold Vth required to localize a single-particle state of energy E (k ⃗) is minimum for the states near the band edge and is maximum for states near the band center, implying a mobility edge starting from the band edge for weak disorder and moving towards the band center as the disorder strength increases. This can be explained in terms of the low-energy Hamiltonian at any point k ⃗ which has the same nature as that at the Dirac point. From the nature of the eigenfunctions, it follows that a weak long-range impurity will cause weak antilocalization effects, which can be suppressed, giving localization if the strength of impurities is sufficiently large to cause intervalley scattering. The intervalley spacing 2 | k ⃗| increases as one moves in from the band edge towards the band center, which is reflected in the behavior of Vth and the mobility edge.

  19. Dirac single particle and plasmon excitations in topological insulators

    NASA Astrophysics Data System (ADS)

    Lupi, Stefano

    Topological Insulators (TIs), like Bi2Se3 and Bi2Te3, are one of the most intriguing issues at focus in Condensed Matter Physics. TIs exhibit a band gap in the bulk like ordinary insulators, but have intrinsic 2D conducting states on their edge and surface. This means that the topology, associated with the electronic wavefunctions of the system, changes discontinuously when passing from the bulk to the surface. The edge states arise from a strong spin-orbit coupling, and they are backscattering protected, i.e. not sensitive to disorder (except that coming from magnetic impurities). Such as graphene, TIs surface charge transport is carried out by Dirac fermions, with a very high surface carrier density (n >= 1013 cm-2) , compared to typical values on metal surfaces. Apart single particle excitations, Dirac fermions in TIs sustain exotic plasmonic (collective) modes whose properties of tunability and temperature dependence can be used for photonics applications at the nanoscale. Moreover, unlike plasmons in metals, Dirac plasmons in TIs are expected to be strongly affected by an external magnetic field B due to fact that the cyclotron frequency is comparable to the the plasmon frequency, in particular when plasmons are engineered in the terahertz region of the electromagnetic spectrum. In this talk, after a general review on the properties of Topological Insulators, I will discuss the terahertz linear response of Dirac plasmons in TIs and their behavior under a strong magnetic field up to 30 T. The appearance of strong non-linear optical effects, when the THz electric field reaches values on the order of 1 MV/cm, will be also discussed. In the second part of the talk, I will discuss the sub-ps dynamics of Dirac single-particle and collective excitations as measured by optical-pump THz-probe experiments. Both the steady state and time-resolved experiments provide a unifying picture of single particle and collective electronic excitations in Topological Insulators.

  20. Tracking single particle rotation: Probing dynamics in four dimensions

    DOE PAGESBeta

    Anthony, Stephen Michael; Yu, Yan

    2015-04-29

    Direct visualization and tracking of small particles at high spatial and temporal resolution provides a powerful approach to probing complex dynamics and interactions in chemical and biological processes. Analysis of the rotational dynamics of particles adds a new dimension of information that is otherwise impossible to obtain with conventional 3-D particle tracking. In this review, we survey recent advances in single-particle rotational tracking, with highlights on the rotational tracking of optically anisotropic Janus particles. Furthermore, strengths and weaknesses of the various particle tracking methods, and their applications are discussed.

  1. Single-particle cryo-EM at crystallographic resolution

    PubMed Central

    Cheng, Yifan

    2015-01-01

    Until only a few years ago, single-particle electron cryo-microscopy (cryo-EM) was usually not the first choice for many structural biologists due to its limited resolution in the range of nanometer to subnanometer. Now, this method rivals X-ray crystallography in terms of resolution and can be used to determine atomic structures of macromolecules that are either refractory to crystallization or difficult to crystallize in specific functional states. In this review, I discuss the recent breakthroughs in both hardware and software that transformed cryo-microscopy, enabling understanding of complex biomolecules and their functions at atomic level. PMID:25910205

  2. Relativistic symmetries in nuclear single-particle spectra

    NASA Astrophysics Data System (ADS)

    Guo, Jian-You; Liang, Hao Zhao; Meng, Jie; Zhou, Shan-Gui

    Symmetry is a fundamental concept in quantum physics. The quasi-degeneracy between single-particle orbitals (n, l, j = l + 1/2) and (n -1, l + 2, j = l + 3/2) indicates a hidden symmetry in atomic nuclei, the so-called pseudospin symmetry. Since the pseudospin symmetry was recognized as a relativistic symmetry in 1990s, many special features, including the spin symmetry for anti-nucleons, and many new concepts have been introduced. In this Chapter, we will illustrate the schematic picture of spin and pseudospin symmetries, derive the basic formalism, highlight the recent progress from several different aspects, and discuss selected open issues in this topic.

  3. Fluorescence preselection of bioaerosol for single-particle mass spectrometry.

    PubMed

    Stowers, M A; van Wuijckhuijse, A L; Marijnissen, J C M; Kientz, Ch E; Ciach, T

    2006-11-20

    We have designed, constructed, and tested a system that pre-selects the biological fraction of airborne particles from the overall aerosol. The preselection is based on fluorescence emission excited by a continuous 266 nm laser beam. This beam is one of two cw beams used to measure the aerodynamic particle size of sampled particles. The intention in our system is that single particles, based on size and fluorescence emission, can be selected and further examined for chemical composition by mass spectrometry. PMID:17086265

  4. Foucault's Toolbox: Critical Insights for Education and Technology Researchers

    ERIC Educational Resources Information Center

    Hope, Andrew

    2015-01-01

    Despite having been a prolific academic, whose work exerts considerable cross-discipline influence, the ideas of Foucault are largely neglected in educational technology scholarship. Having provided an initial brief overview of the sparse use of Foucault's work in this sub-field, this paper then seeks to generate new understandings, arguing that…

  5. Beyond Subjection: Notes on the Later Foucault and Education

    ERIC Educational Resources Information Center

    Leask, Ian

    2012-01-01

    This article argues against the doxa that Foucault's analysis of education inevitably undermines self-originating ethical intention on the part of teachers or students. By attending to Foucault's lesser known, later work--in particular, the notion of "biopower" and the deepened level of materiality it entails--the article shows how the earlier…

  6. Transgression or Stasis? Challenging Foucault in LIS Theory

    ERIC Educational Resources Information Center

    Buschman, John

    2007-01-01

    Michel Foucault (1926-84) is a primary thinker informing the construction of a critical theory of library and information science (LIS), or librarianship. He is widely cited and is adapted in various ways that focus on LIS forms of power, discourse, and so on. Others have addressed Foucault's topics, but he remains central. Librarianship has taken…

  7. Foucault Dissipation in a Rolling Cylinder: A Webcam Quantitative Study

    ERIC Educational Resources Information Center

    Bonanno, A.; Bozzo, G.; Camarca, M.; Sapia, P.

    2011-01-01

    In this paper we present an experimental strategy to measure the micro power dissipation due to Foucault "eddy" currents in a copper cylinder rolling on two parallel conductive rails in the presence of a magnetic field. Foucault power dissipation is obtained from kinematical measurements carried out by using a common PC webcam and video analysis…

  8. Global phase diagram and single particle excitations in Kondo insulators

    NASA Astrophysics Data System (ADS)

    Si, Qimiao; Pixley, Jedediah; Yu, Rong; Paschen, Silke

    Motivated by quantum criticality in Kondo insulators tuned by pressure or doping we study the effects of magnetic frustration and the properties of the single particle excitations in a Kondo lattice model. Focusing on the Kondo insulating limit we study the Shastry-Sutherland Kondo lattice and determine the zero temperature phase diagram, which incorporates a valence bond solid, antiferromagnet, and Kondo insulating ground states, with metal-to-insulator quantum phase transitions. We argue that this phase diagram is generic and represents a ``global'' phase diagram of Kondo insulators in terms of quantum fluctuations and the Kondo interaction. We then focus on the momentum distribution of single particle excitations within the Kondo insulating ground state. We show how features of the Fermi-surface of the underlying conduction electrons appear in the Kondo insulating phase. Lastly, we discuss the implications of our results for quantum criticality in Kondo insulators as well as for the recent de Haas-von Alphen measurements in the Kondo insulator SmB6.

  9. Single-particle absorption spectroscopy by photothermal contrast.

    PubMed

    Yorulmaz, Mustafa; Nizzero, Sara; Hoggard, Anneli; Wang, Lin-Yung; Cai, Yi-Yu; Su, Man-Nung; Chang, Wei-Shun; Link, Stephan

    2015-05-13

    Removing effects of sample heterogeneity through single-molecule and single-particle techniques has advanced many fields. While background free luminescence and scattering spectroscopy is widely used, recording the absorption spectrum only is rather difficult. Here we present an approach capable of recording pure absorption spectra of individual nanostructures. We demonstrate the implementation of single-particle absorption spectroscopy on strongly scattering plasmonic nanoparticles by combining photothermal microscopy with a supercontinuum laser and an innovative calibration procedure that accounts for chromatic aberrations and wavelength-dependent excitation powers. Comparison of the absorption spectra to the scattering spectra of the same individual gold nanoparticles reveals the blueshift of the absorption spectra, as predicted by Mie theory but previously not detectable in extinction measurements that measure the sum of absorption and scattering. By covering a wavelength range of 300 nm, we are furthermore able to record absorption spectra of single gold nanorods with different aspect ratios. We find that the spectral shift between absorption and scattering for the longitudinal plasmon resonance decreases as a function of nanorod aspect ratio, which is in agreement with simulations. PMID:25849105

  10. On-line single particle analysis of environmental tobacco smoke

    SciTech Connect

    Prather, K.A.; Morrical, B.O.

    1995-12-01

    Environmental Tobacco Smoke (ETS) is a major component in indoor and outdoor air pollution. It has been estimated that ETS accounts for approximately 2.7% of fine organic aerosol emissions in the Los Angeles area and the adverse health effects of cigarette emissions have been well documented. Particulate analysis by conventional analytical methods, such as GC/MS, do not provide information on individual aerosol particles due to the off-line collection and sampling procedures. Aerosol Time-Flight Mass Spectrometry is an on-line analytical technique that is uniquely capable of single particle analysis, simultaneously providing information on particle size and chemical composition. It will be demonstrated that this technique can be used to show how the chemical composition of ETS particles changes as a function of size. Data demonstrating the ability to monitor chemical composition and size change as a function of time will also be presented.

  11. Optimization of magnetic switches for single particle and cell transport

    NASA Astrophysics Data System (ADS)

    Abedini-Nassab, Roozbeh; Murdoch, David M.; Kim, CheolGi; Yellen, Benjamin B.

    2014-06-01

    The ability to manipulate an ensemble of single particles and cells is a key aim of lab-on-a-chip research; however, the control mechanisms must be optimized for minimal power consumption to enable future large-scale implementation. Recently, we demonstrated a matter transport platform, which uses overlaid patterns of magnetic films and metallic current lines to control magnetic particles and magnetic-nanoparticle-labeled cells; however, we have made no prior attempts to optimize the device geometry and power consumption. Here, we provide an optimization analysis of particle-switching devices based on stochastic variation in the particle's size and magnetic content. These results are immediately applicable to the design of robust, multiplexed platforms capable of transporting, sorting, and storing single cells in large arrays with low power and high efficiency.

  12. Membrane protein structures without crystals, by single particle electron cryomicroscopy

    PubMed Central

    Vinothkumar, Kutti R

    2015-01-01

    It is an exciting period in membrane protein structural biology with a number of medically important protein structures determined at a rapid pace. However, two major hurdles still remain in the structural biology of membrane proteins. One is the inability to obtain large amounts of protein for crystallization and the other is the failure to get well-diffracting crystals. With single particle electron cryomicroscopy, both these problems can be overcome and high-resolution structures of membrane proteins and other labile protein complexes can be obtained with very little protein and without the need for crystals. In this review, I highlight recent advances in electron microscopy, detectors and software, which have allowed determination of medium to high-resolution structures of membrane proteins and complexes that have been difficult to study by other structural biological techniques. PMID:26435463

  13. Optimization of magnetic switches for single particle and cell transport

    SciTech Connect

    Abedini-Nassab, Roozbeh; Yellen, Benjamin B.; Murdoch, David M.; Kim, CheolGi

    2014-06-28

    The ability to manipulate an ensemble of single particles and cells is a key aim of lab-on-a-chip research; however, the control mechanisms must be optimized for minimal power consumption to enable future large-scale implementation. Recently, we demonstrated a matter transport platform, which uses overlaid patterns of magnetic films and metallic current lines to control magnetic particles and magnetic-nanoparticle-labeled cells; however, we have made no prior attempts to optimize the device geometry and power consumption. Here, we provide an optimization analysis of particle-switching devices based on stochastic variation in the particle's size and magnetic content. These results are immediately applicable to the design of robust, multiplexed platforms capable of transporting, sorting, and storing single cells in large arrays with low power and high efficiency.

  14. Single Particle Jumps in Sheared SiO2

    NASA Astrophysics Data System (ADS)

    McMahon, Sean; Vollmayr-Lee, Katharina; Cookmeyer, Jonathan; Horbach, Juergen

    We study the dynamics of a sheared glass via molecular dynamics simulations. Using the BKS potential we simulate the strong glass former SiO2. The system is initially well equilibrated at a high temperature, then quenched to a temperature below the glass transition, and, after a waiting time at the desired low temperature, sheared with constant strain rate. We present preliminary results of an analysis of single particle trajectories of the sheared glass. We acknowledge the support via NSF REU Grant #PHY-1156964, DoD ASSURE program, and NSF-MRI CHE-1229354 as part of the MERCURY high-performance computer consortium. We thank G.P. Shrivastav, Ch. Scherer and B. Temelso.

  15. Horizontal deflection of single particle in a paramagnetic fluid.

    PubMed

    Liu, S; Yi, Xiang; Leaper, M; Miles, N J

    2014-06-01

    This paper describes the horizontal deflection behaviour of a single particle in paramagnetic fluids under a high-gradient superconducting magnetic field. A glass box was designed to carry out experiments and test assumptions. It was found that the particles were deflected away from the magnet bore centre and particles with different density and/or susceptibility settled at a certain position on the container floor due to the combined forces of gravity and magneto-Archimedes as well as lateral buoyant (displacement) force. Matlab was chosen to simulate the movement of the particle in the magnetic fluid, the simulation results were in good accordance with experimental data. The results presented here, though, are still very much in their infancy, which could potentially form the basis of a new approach to separating materials based on a combination of density and susceptibility. PMID:24894886

  16. Single-particle spectroscopic measurements of fluorescent graphene quantum dots.

    PubMed

    Xu, Qinfeng; Zhou, Qi; Hua, Zheng; Xue, Qi; Zhang, Chunfeng; Wang, Xiaoyong; Pan, Dengyu; Xiao, Min

    2013-12-23

    We have performed the first single-particle spectroscopic measurements on individual graphene quantum dots (GQDs) and revealed several intriguing fluorescent phenomena that are otherwise hidden in the optical studies of ensemble GQDs. First, despite noticeable differences in the size and the number of layers from particle to particle, all of the GQDs studied possess almost the same spectral lineshapes and peak positions. Second, GQDs with more layers are normally brighter emitters but are associated with shorter fluorescent lifetimes. Third, the fluorescent spectrum of GQDs was red-shifted upon being aged in air, possibly due to the water desorption effect. Finally, the missing emission of single photons and stable fluorescence without any intermittent behavior were observed from individual GQDs. PMID:24251867

  17. Towards single particle imaging of human chromosomes at SACLA

    NASA Astrophysics Data System (ADS)

    Robinson, Ian; Schwenke, Joerg; Yusuf, Mohammed; Estandarte, Ana; Zhang, Fucai; Chen, Bo; Clark, Jesse; Song, Changyong; Nam, Daewoong; Joti, Yasumasa; Tono, Kensuke; Yabashi, Makina; Ratnasari, Gina; Kaneyoshi, Kohei; Takata, Hideaki; Fukui, Kiichi

    2015-12-01

    Single particle imaging (SPI) is one of the front-page opportunities which were used to motivate the construction of the first x-ray free electron lasers (XFELs). SPI’s big advantage is that it avoids radiation damage to biological samples because the diffraction takes place in femtosecond single shots before any atomic motion can take place in the sample, hence before the onset of radiation damage. This is the ‘diffract before destruction’ theme, destruction being assured from the high x-ray doses used. This article reports our collaboration’s first attempt at SPI using the SACLA XFEL facility in June 2015. The report is limited to experience with the instrumentation and examples of data because we have not yet had time to invert them to images.

  18. Simultaneous Single-Particle Superlocalization and Rotational Tracking

    SciTech Connect

    Gu, Yan; Wang, Gufeng; Fang, Ning

    2013-01-30

    Superlocalization of single molecules and nanoparticles has become an essential procedure to bring new insights into nanoscale structures and dynamics of biological systems. In the present study, superlocalization is combined with the newly introduced differential interference contrast (DIC) microscopy-based single-particle orientation and rotational tracking. The new technique overcomes the difficulty in localization of the antisymmetric DIC point spread function by using a dual-modality microscope configuration for simultaneous rotational tracking and localization of single gold nanorods with nanometer-scale precision. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment. This technique has great potential in the study of biological processes where both localization and rotational information are required.

  19. Authenticated multi-user quantum key distribution with single particles

    NASA Astrophysics Data System (ADS)

    Lin, Song; Wang, Hui; Guo, Gong-De; Ye, Guo-Hua; Du, Hong-Zhen; Liu, Xiao-Fen

    2016-03-01

    Quantum key distribution (QKD) has been growing rapidly in recent years and becomes one of the hottest issues in quantum information science. During the implementation of QKD on a network, identity authentication has been one main problem. In this paper, an efficient authenticated multi-user quantum key distribution (MQKD) protocol with single particles is proposed. In this protocol, any two users on a quantum network can perform mutual authentication and share a secure session key with the assistance of a semi-honest center. Meanwhile, the particles, which are used as quantum information carriers, are not required to be stored, therefore the proposed protocol is feasible with current technology. Finally, security analysis shows that this protocol is secure in theory.

  20. Organic aerosol mixing observed by single-particle mass spectrometry.

    PubMed

    Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

    2013-12-27

    We present direct measurements of mixing between separately prepared organic aerosol populations in a smog chamber using single-particle mass spectra from the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Docosane and docosane-d46 (22 carbon linear solid alkane) did not show any signs of mixing, but squalane and squalane-d62 (30 carbon branched liquid alkane) mixed on the time scale expected from a condensational-mixing model. Docosane and docosane-d46 were driven to mix when the chamber temperature was elevated above the melting point for docosane. Docosane vapors were shown to mix into squalane-d62, but not the other way around. These results are consistent with low diffusivity in the solid phase of docosane particles. We performed mixing experiments on secondary organic aerosol (SOA) surrogate systems finding that SOA derived from toluene-d8 (a surrogate for anthropogenic SOA (aSOA)) does not mix into squalane (a surrogate for hydrophobic primary organic aerosol (POA)) but does mix into SOA derived from α-pinene (biogenic SOA (bSOA) surrogate). For the aSOA/POA, the volatility of either aerosol does not limit gas-phase diffusion, indicating that the two particle populations do not mix simply because they are immiscible. In the aSOA/bSOA system, the presence of toluene-d8-derived SOA molecules in the α-pinene-derived SOA provides evidence that the diffusion coefficient in α-pinene-derived SOA is high enough for mixing on the time scale of 1 min. The observations from all of these mixing experiments are generally invisible to bulk aerosol composition measurements but are made possible with single-particle composition data. PMID:24131283

  1. Foucault's notion of problematization: a methodological discussion of the application of Foucault's later work to nursing research.

    PubMed

    Frederiksen, Kirsten; Lomborg, Kirsten; Beedholm, Kirsten

    2015-09-01

    This study takes its point of departure in an oft-voiced critique that the French philosopher Michel Foucault gives discourse priority over practice, thereby being deterministic and leaving little space for the individual to act as an agent. Based on an interpretation of the latter part of Foucault's oeuvre, we argue against this critique and provide a methodological discussion of the perception that Foucault's method constitutes, primarily, discourse analysis. We argue that it is possible to overcome this critique of Foucault's work by the application of methodological tools adapted from Foucault's later writings and his diagnosis of his own work as studies of forms of problematization. To shed light on the possibilities that this approach offers to the researcher, we present a reading of aspects of Foucault's work, with a focus on his notion of forms of problematization. Furthermore, we elaborate on concepts from his so-called genealogical period, namely 'the dispositive', strategy and tactics. Our interpretation is supported by examples from a study of the emergence of Danish nursing education, which is based on an analytical framework that we developed in the light of an interpretation of aspects of Foucault's work. PMID:25712771

  2. Cluster analysis of WIBS single particle bioaerosol data

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Huffman, J. A.; Kaye, P. H.; Foot, V. E.; Gallagher, M.

    2012-09-01

    Hierarchical agglomerative cluster analysis was performed on single-particle multi-spatial datasets comprising optical diameter, asymmetry and three different fluorescence measurements, gathered using two dual Waveband Integrated Bioaerosol Sensor (WIBS). The technique is demonstrated on measurements of various fluorescent and non-fluorescent polystyrene latex spheres (PSL) before being applied to two separate contemporaneous ambient WIBS datasets recorded in a forest site in Colorado, USA as part of the BEACHON-RoMBAS project. Cluster analysis results between both datasets are consistent. Clusters are tentatively interpreted by comparison of concentration time series and cluster average measurement values to the published literature (of which there is a paucity) to represent: non-fluorescent accumulation mode aerosol; bacterial agglomerates; and fungal spores. To our knowledge, this is the first time cluster analysis has been applied to long term online PBAP measurements. The novel application of this clustering technique provides a means for routinely reducing WIBS data to discrete concentration time series which are more easily interpretable, without the need for any a priori assumptions concerning the expected aerosol types. It can reduce the level of subjectivity compared to the more standard analysis approaches, which are typically performed by simple inspection of various ensemble data products. It also has the advantage of potentially resolving less populous or subtly different particle types. This technique is likely to become more robust in the future as fluorescence-based aerosol instrumentation measurement precision, dynamic range and the number of available metrics is improved.

  3. Instrument Development for Single-Particle Albedo Measurements

    NASA Astrophysics Data System (ADS)

    Sanford, T. J.; Murphy, D. M.; Fox, R. W.

    2008-12-01

    The ASTER (Aerosol Scattering To Extinction Ratio) instrument simultaneously measures scattering and extinction by single aerosol particles from which the albedo for each particle can be determined. ASTER employs a high-Q laser cavity to amplify loses in the cavity caused by individual particles to produce measurable extinction signals. The instrument collects light in three separate channels representing backward, forward, and wide-angle scattering. The ratio of forward to total scattering provides a proxy measurement for particle size that Mie scattering calculations show to be largely independent of particle refractive index for diameters below about 2 micrometers. Laboratory measurements on particles of known sizes and scattering properties have been used to assess the performance of the instrument and as a guide for ongoing modifications for eventual field deployment. Results from the current version of the instrument will be presented and compared to previous ASTER data to demonstrate improved performance. Data taken from ambient air have shown modes of highly absorbing particles that would not have been evident from bulk measurements. The single-particle nature of the measurements will provide additional information to complement existing methods for measuring aerosol albedos in the atmosphere.

  4. Automated single particle detection and tracking for large microscopy datasets

    PubMed Central

    Wilson, Rhodri S.; Yang, Lei; Dun, Alison; Smyth, Annya M.; Duncan, Rory R.; Rickman, Colin

    2016-01-01

    Recent advances in optical microscopy have enabled the acquisition of very large datasets from living cells with unprecedented spatial and temporal resolutions. Our ability to process these datasets now plays an essential role in order to understand many biological processes. In this paper, we present an automated particle detection algorithm capable of operating in low signal-to-noise fluorescence microscopy environments and handling large datasets. When combined with our particle linking framework, it can provide hitherto intractable quantitative measurements describing the dynamics of large cohorts of cellular components from organelles to single molecules. We begin with validating the performance of our method on synthetic image data, and then extend the validation to include experiment images with ground truth. Finally, we apply the algorithm to two single-particle-tracking photo-activated localization microscopy biological datasets, acquired from living primary cells with very high temporal rates. Our analysis of the dynamics of very large cohorts of 10 000 s of membrane-associated protein molecules show that they behave as if caged in nanodomains. We show that the robustness and efficiency of our method provides a tool for the examination of single-molecule behaviour with unprecedented spatial detail and high acquisition rates. PMID:27293801

  5. Strategies for single particle manipulation using acoustic and flow fields.

    PubMed

    Oberti, S; Möller, D; Neild, A; Dual, J; Beyeler, F; Nelson, B J; Gutmann, S

    2010-02-01

    Acoustic radiation forces have often been used for the manipulation of large amounts of micrometer sized suspended particles. The nature of acoustic standing wave fields is such that they are present throughout the whole fluidic volume; this means they are well suited to such operations, with all suspended particles reacting at the same time upon exposure. Here, this simultaneous positioning capability is exploited to pre-align particles along the centerline of channels, so that they can successively be removed by means of an external tool for further analysis. This permits a certain degree of automation in single particle manipulation processes to be achieved as initial identification of particles' location is no longer necessary, rather predetermined. Two research fields in which applications are found have been identified. First, the manipulation of copolymer beads and cells using a microgripper is presented. Then, sample preparation for crystallographic analysis by positioning crystals into a loop using acoustic manipulation and a laminar flow will be presented. PMID:19837446

  6. DETERMINATION OF STOKES SHAPE FACTOR FOR SINGLE PARTICLES AND AGGLOMERATES

    SciTech Connect

    Matyas, Josef; Schaible, Micah J.; Vienna, John D.

    2011-09-01

    The large octahedral crystals of spinel can precipitate from glass during the high-level waste vitrification process and potentially block the glass discharge riser of electrically heated ceramic melters. To help predict the settling behavior of spinel in the riser, the settling of single particles and agglomerates was studied in stagnant and transparent viscosity oils at room temperature with developed optical particle-dynamics-analyzer. Determined dimensions and terminal settling velocities of particles were used for calculation of their Stokes shape factors. Calculated shape factor for the glass beads was almost identical with the theoretical shape factor of 2/9 for a perfect sphere. The shape factor for single spinel crystal was about 7.6 % higher compare to the theoretically predicted value for octahedron. Stokes shape factor of irregularly shaped multi-particle agglomerates was lower than that of the glass beads and individual spinel crystals because of the higher surface drag caused by the larger surface area to volume ratio.

  7. Cluster analysis of WIBS single-particle bioaerosol data

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Huffman, J. A.; Kaye, P. H.; Foot, V. E.; Gallagher, M.

    2013-02-01

    Hierarchical agglomerative cluster analysis was performed on single-particle multi-spatial data sets comprising optical diameter, asymmetry and three different fluorescence measurements, gathered using two dual Wideband Integrated Bioaerosol Sensors (WIBSs). The technique is demonstrated on measurements of various fluorescent and non-fluorescent polystyrene latex spheres (PSL) before being applied to two separate contemporaneous ambient WIBS data sets recorded in a forest site in Colorado, USA, as part of the BEACHON-RoMBAS project. Cluster analysis results between both data sets are consistent. Clusters are tentatively interpreted by comparison of concentration time series and cluster average measurement values to the published literature (of which there is a paucity) to represent the following: non-fluorescent accumulation mode aerosol; bacterial agglomerates; and fungal spores. To our knowledge, this is the first time cluster analysis has been applied to long-term online primary biological aerosol particle (PBAP) measurements. The novel application of this clustering technique provides a means for routinely reducing WIBS data to discrete concentration time series which are more easily interpretable, without the need for any a priori assumptions concerning the expected aerosol types. It can reduce the level of subjectivity compared to the more standard analysis approaches, which are typically performed by simple inspection of various ensemble data products. It also has the advantage of potentially resolving less populous or subtly different particle types. This technique is likely to become more robust in the future as fluorescence-based aerosol instrumentation measurement precision, dynamic range and the number of available metrics are improved.

  8. Chromatin dynamics during interphase explored by single-particle tracking.

    PubMed

    Levi, Valeria; Gratton, Enrico

    2008-01-01

    Our view of the structure and function of the interphase nucleus has changed drastically in recent years. It is now widely accepted that the nucleus is a well organized and highly compartmentalized organelle and that this organization is intimately related to nuclear function. In this context, chromatin-initially considered a randomly entangled polymer-has also been shown to be structurally organized in interphase and its organization was found to be very important to gene regulation. Relevant and not completely answered questions are how chromatin organization is achieved and what mechanisms are responsible for changes in the positions of chromatin loci in the nucleus. A significant advance in the field resulted from tagging chromosome sites with bacterial operator sequences, and visualizing these tags using green fluorescent protein fused with the appropriate repressor protein. Simultaneously, fluorescence imaging techniques evolved significantly during recent years, allowing observation of the time evolution of processes in living specimens. In this context, the motion of the tagged locus was observed and analyzed to extract quantitative information regarding its dynamics. This review focuses on recent advances in our understanding of chromatin dynamics in interphase with the emphasis placed on the information obtained from single-particle tracking (SPT) experiments. We introduce the basis of SPT methods and trajectory analysis, and summarize what has been learnt by using this new technology in the context of chromatin dynamics. Finally, we briefly describe a method of SPT in a two-photon excitation microscope that has several advantages over methods based on conventional microscopy and review the information obtained using this novel approach to study chromatin dynamics. PMID:18461483

  9. Chromatin dynamics during interphase explored by single particle tracking

    PubMed Central

    Levi, Valeria; Gratton, Enrico

    2009-01-01

    Our view of the structure and function of the interphase nucleus has drastically changed in the last years. It is now widely accepted that the nucleus is a well organized and highly compartmentalized organelle and that this organization is intimately related to nuclear function. In this context, chromatin -initially considered a randomly entangled polymer- has also been shown to be structurally organized in interphase and its organization was found to be very important to gene regulation. Relevant and not completely answered questions are how chromatin organization is achieved and what mechanisms are responsible for changes in the positions of chromatin loci in the nucleus. A significant advance in the field resulted from tagging chromosome sites with bacterial operator sequences, and visualizing these tags using green fluorescent protein fused with the appropriate repressor protein. Simultaneously, fluorescence imaging techniques significantly evolved during the last years allowing the observation of the time evolution of processes in living specimens. In this context, the motion of the tagged locus was observed and analyzed to extract quantitative information regarding its dynamics. This review focuses on recent advances in our understanding of chromatin dynamics in interphase with the emphasis placed on the information obtained from single particle tracking (SPT) experiments. We introduce the basis of SPT methods and trajectories analysis, and summarize what has been learnt by using this new technology in the context of chromatin dynamics. Finally, we briefly describe a method of SPT in a two-photon excitation microscope that has several advantages over methods based on conventional microscopy and review the information obtained by using this novel approach to study chromatin dynamics. PMID:18461483

  10. Drift correction of the dissolved signal in single particle ICPMS.

    PubMed

    Cornelis, Geert; Rauch, Sebastien

    2016-07-01

    A method is presented where drift, the random fluctuation of the signal intensity, is compensated for based on the estimation of the drift function by a moving average. It was shown using single particle ICPMS (spICPMS) measurements of 10 and 60 nm Au NPs that drift reduces accuracy of spICPMS analysis at the calibration stage and during calculations of the particle size distribution (PSD), but that the present method can again correct the average signal intensity as well as the signal distribution of particle-containing samples skewed by drift. Moreover, deconvolution, a method that models signal distributions of dissolved signals, fails in some cases when using standards and samples affected by drift, but the present method was shown to improve accuracy again. Relatively high particle signals have to be removed prior to drift correction in this procedure, which was done using a 3 × sigma method, and the signals are treated separately and added again. The method can also correct for flicker noise that increases when signal intensity is increased because of drift. The accuracy was improved in many cases when flicker correction was used, but when accurate results were obtained despite drift, the correction procedures did not reduce accuracy. The procedure may be useful to extract results from experimental runs that would otherwise have to be run again. Graphical Abstract A method is presented where a spICP-MS signal affected by drift (left) is corrected (right) by adjusting the local (moving) averages (green) and standard deviations (purple) to the respective values at a reference time (red). In combination with removing particle events (blue) in the case of calibration standards, this method is shown to obtain particle size distributions where that would otherwise be impossible, even when the deconvolution method is used to discriminate dissolved and particle signals. PMID:27095581

  11. The character of single particle sulfate in Baltimore

    NASA Astrophysics Data System (ADS)

    Lake, Derek A.; Tolocka, Michael P.; Johnston, Murray V.; Wexler, Anthony S.

    2004-10-01

    A major component of PM2.5 in urban aerosol in the eastern United States is sulfate. The eastern US is heavily influenced by regional sources (e.g. coal combustion in the Ohio River Valley) and also by local sources. From March to December 2002, the Baltimore aerosol was characterized with the real-time single-particle mass spectrometer RSMS III. RSMS III is capable of simultaneous positive/negative ion detection of size selected particles between 45 and 1250 nm in diameter. The negative ion detection ability allows sulfate to be monitored. Particles were first sorted into two groups based on the negative ion spectra: (1) those with sulfate detected and (2) those with no sulfate detected. The two groups were further sub-divided by ART 2-a analysis of the positive ion spectra to determine which particle compositions are most/least likely to contain detectable sulfate. A separate analysis was also performed on the positive ion spectra to determine the presence/absence of specific metals in the group of particles with and without sulfate. The correlation of positive and negative ion spectra in this manner allows particle types that are strongly associated with sulfate to be distinguished from those which are not. Particle types strongly correlated with sulfate are nitrate, organic carbon/nitrate (OCAN) and vanadium. Particle types weakly associated with sulfate include carbon and potassium/sodium. Many particles contain both sulfate and nitrate, which suggests that they are acid neutralized. While laser ablation mass spectrometry has inherent limitations for particulate sulfate detection, the results presented here suggest that sulfate detection by this method is a reasonable indicator of particle source and atmospheric transformation.

  12. Proton Single-Particle States In The Heaviest Actinide Nuclei

    SciTech Connect

    Ahmad, I.; Kondev, F.G.; Moore, E.F.; Chasman, R.R.; Carpenter, M.P.; Greene, J.P.; Janssens, R.V.F.; Lauritsen, T.; Lister, C.J.; Seweryniak, D.; Hoff, R.W.; Evans, J.E.; Lougheed, R.W.; Porter, C.E.; Felker, L.K.

    2005-04-05

    The level structure of 249Bk has been investigated by measuring the {gamma}-ray spectra following the {alpha} decay of a chemically and isotopically pure 253Es sample. Alpha-gamma coincidence measurement was performed using a Si detector for {alpha} particles and a 25% Ge detector for {gamma} rays. A gamma-gamma coincidence measurement was performed with the Gammasphere spectrometer. The Es sample was obtained by extracting the 253Es which grew in a 253Cf source material produced in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Additional information on the 249Bk levels was obtained from the study of {gamma} rays produced in the {beta}- decay of 249Cm. The 249Cm sample was produced by neutron irradiation of 248Cm. Using the results of the present study and the results of previous 248Cm({alpha},t) and 248Cm(3He,d) reaction spectra, the following single-particle states have been identified in 249Bk: 7/2+[633], 0.0 keV; 3/2-[521], 8.78 keV; 1/2+[400], 377.55 keV: 5/2+[642], 389.17 keV; 1/2-[530], 569.19 keV; 1/2-[521], 643.0 keV; 5/2-[523], 672.8 keV; 9/2+[624], 1075.1 keV. Four vibrational bands were identified at 767.9, 932.2, 1150.7 and 1223.0 keV with tentative assignments of {l_brace}7/2+[633]x1-{r_brace}9/2-, {l_brace}7/2+[633]x0-{r_brace}7/2-, {l_brace}7/2+[633]x1-{r_brace}5/2- and {l_brace}7/2+[633]x0+{r_brace}7/2+, respectively.

  13. A Microfluidic-based Hydrodynamic Trap for Single Particles

    PubMed Central

    Johnson-Chavarria, Eric M.; Tanyeri, Melikhan; Schroeder, Charles M.

    2011-01-01

    The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in

  14. Foucault test: a quantitative evaluation method.

    PubMed

    Rodríguez, Gustavo; Villa, Jesús; Ivanov, Rumen; González, Efrén; Martínez, Geminiano

    2016-08-01

    Reliable and accurate testing methods are essential to guiding the polishing process during the figuring of optical telescope mirrors. With the natural advancement of technology, the procedures and instruments used to carry out this delicate task have consistently increased in sensitivity, but also in complexity and cost. Fortunately, throughout history, the Foucault knife-edge test has shown the potential to measure transverse aberrations in the order of the wavelength, mainly when described in terms of physical theory, which allows a quantitative interpretation of its characteristic shadowmaps. Our previous publication on this topic derived a closed mathematical formulation that directly relates the knife-edge position with the observed irradiance pattern. The present work addresses the quite unexplored problem of the wavefront's gradient estimation from experimental captures of the test, which is achieved by means of an optimization algorithm featuring a proposed ad hoc cost function. The partial derivatives thereby calculated are then integrated by means of a Fourier-based algorithm to retrieve the mirror's actual surface profile. To date and to the best of our knowledge, this is the very first time that a complete mathematical-grounded treatment of this optical phenomenon is presented, complemented by an image-processing algorithm which allows a quantitative calculation of the corresponding slope at any given point of the mirror's surface, so that it becomes possible to accurately estimate the aberrations present in the analyzed concave device just through its associated foucaultgrams. PMID:27505659

  15. Errant life, molecular biology, and biopower: Canguilhem, Jacob, and Foucault.

    PubMed

    Talcott, Samuel

    2014-01-01

    This paper considers the theoretical circumstances that urged Michel Foucault to analyse modern societies in terms of biopower. Georges Canguilhem's account of the relations between science and the living forms an essential starting point for Foucault's own later explorations, though the challenges posed by the molecular revolution in biology and François Jacob's history of it allowed Foucault to extend and transform Canguilhem's philosophy of error. Using archival research into his 1955-1956 course on "Science and Error," I show that, for Canguilhem, it is inauthentic to treat a living being as an error, even if living things are capable of making errors in the domain of knowledge. The emergent molecular biology in the 1960s posed a grave challenge, however, since it suggested that individuals could indeed be errors of genetic reproduction. The paper discusses how Canguilhem and Foucault each responded to this by examining, among other texts, their respective reviews of Jacob's The Logic of the Living. For Canguilhem this was an opportunity to reaffirm the creativity of life in the living individual, which is not a thing to be evaluated, but the source of values. For Foucault, drawing on Jacob's work, this was the opportunity to develop a transformed account of valuation by posing biopower as the DNA of society. Despite their disagreements, the paper examines these three authors as different iterations of a historical epistemology attuned to errancy, error, and experimentation. PMID:25515360

  16. Single particle measurements of material line stretching in turbulence: Experiments

    NASA Astrophysics Data System (ADS)

    Kramel, Stefan; Tympel, Saskia; Toschi, Federico; Voth, Greg

    2015-11-01

    We find that particles in the shape of chiral dipoles display a preferential rotation direction in three dimensional isotropic turbulence. The particles consist of two helical ends with opposite chirality that are connected by a straight rod. They are fabricated using 3D printing and have an aspect ratio of 10 and a length in the inertial range of our flow between oscillating grids. Due to their high aspect ratio, they move like material lines. Because material lines align with the extentional eigenvectors of the velocity gradient tensor they experience a mean stretching in turbulence. The stretching of a chiral dipole produces a rotation about the dipole axis and so chiral dipoles experience a non-zero mean spinning rate in turbulence. These results provide a first direct experimental measurement of the rate of material line stretching in turbulence.

  17. Léon Foucault: His Life, Times and Achievements

    NASA Astrophysics Data System (ADS)

    Aczel, Amir D.

    Léon Foucaults dramatic demonstration of the rotation of the Earth using a freely-rotating pendulum in 1850 shocked the world of science. Scientists were stunned that such a simple proof of our planets rotation had to wait so long to be developed. Foucaults public demonstration, which was repeated at many locations around the world, put an end to centuries of doubt about the Earths rotation - skepticism that had been bolstered since antiquity by Aristotelian philosophy and scripture. This paper puts Foucaults pendulum experiments in context, surveying the life and work of this extraordinary physicist, a man who achieved much - including work on measuring the speed of light, microscopy, astronomy, and photography - without formal training in the sciences.

  18. Foucault imaging by using non-dedicated transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-01

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  19. Single-particle spectral density of a Bose gas in the two-fluid hydrodynamic regime

    SciTech Connect

    Arahata, Emiko; Nikuni, Tetsuro; Griffin, Allan

    2011-11-15

    In Bose superfluids, the single-particle Green's function can be directly related to the superfluid velocity-velocity correlation function in the hydrodynamic regime. An explicit expression for the single-particle spectral density was originally written down by Hohenberg and Martin in 1965, starting from the two-fluid equations for a superfluid. We give a simple derivation of their results. Using these results, we calculate the relative weights of first and second sound modes in the single-particle spectral density as a function of temperature in a uniform Bose gas. We show that the second sound mode makes a dominant contribution to the single-particle spectrum in a relatively high-temperature region. We also discuss the possibility of experimental observation of the second sound mode in a Bose gas by photoemission spectroscopy.

  20. Foucault at School: Discipline, Education and Agency in "Harry Potter"

    ERIC Educational Resources Information Center

    Wolosky, Shira

    2014-01-01

    The formative power of children's literature is both great and suspicious. As a resource of socialization, the construction and experience of children's literature can be seen as modes of disciplinary coercion such as Michel Foucault has anatomized. "Harry Potter", as a "craze" phenomenon, has attracted particular…

  1. A Critical Theory of the Self: Wittgenstein, Nietzsche, Foucault.

    ERIC Educational Resources Information Center

    Marshall, James D.

    2001-01-01

    Argues for a Foucauldean position on the self to extend critical theory. Discusses several philosophical accounts of the self, including the work of such philosophers as Descartes, Hume, Locke, Rousseau, Schopenhauer, Wittgenstein, and Nietzsche. Concludes that Foucault's philosophy provides a powerful critical conception of the self for critical…

  2. Applying Foucault's "Archaeology" to the Education of School Counselors

    ERIC Educational Resources Information Center

    Shenker, Susan S.

    2008-01-01

    Counselor educators can utilize the ideas of philosopher Michel Foucault in preparing preservice school counselors for their work with K-12 students in public schools. The Foucaultian ideas of "governmentality," "technologies of domination," "received truths," "power/knowledge," "discontinuity," and "archaeology" can contribute to students'…

  3. What Makes the Foucault Pendulum Move among the Stars?

    ERIC Educational Resources Information Center

    Phillips, Norman

    2004-01-01

    Foucault's pendulum exhibition in 1851 occurred in an era now known by development of the theorems of Coriolis and the formulation of dynamical meteorology by Ferrel. Yet today the behavior of the pendulum is often misunderstood. The existence of a horizontal component of Newtonian gravitation is essential for understanding the behavior with…

  4. Putting Foucault to Work: Understanding Power in a Rural School

    ERIC Educational Resources Information Center

    Freie, Carrie; Eppley, Karen

    2014-01-01

    This case study uses the work of Michel Foucault to challenge the normalization of the principal's role and to examine the complex power relations of a rural school and community in the midst of a closure/consolidation and subsequent reopening as a charter school. In so doing, we move beyond analysis of best practices and toward a more…

  5. Talking to Foucault: Examining Marginalization and Exclusion in Academic Science

    ERIC Educational Resources Information Center

    McClam, Sherie

    2006-01-01

    In this article, the author invites everyone to join her as she follows Laurel Richardson's advice to use writing as a method of inquiry. To do so, she engages in a fictional conversation with Michel Foucault--later joined by actor-network theorist Michel Callon--in which she talks through and constructs understanding(s) of and from her research…

  6. Foucault on Camp: What Does His Work Offer Outdoor Education?

    ERIC Educational Resources Information Center

    Zink, Robyn; Burrows, Lisette

    2006-01-01

    In this paper we examine aspects of French social theorist, Michel Foucault's work and the contributions these can make to understanding practices in outdoor education. We look specifically at his notions of practice, discourse, power and the self and the lines of questioning that these concepts make possible in relation to outdoor education. We…

  7. Pedagogy Without Humanism: Foucault and the Subject of Education.

    ERIC Educational Resources Information Center

    Biesta, Gert J. J.

    1998-01-01

    Examines the postmodern critique of the modern conception of human subjectivity and what it entails for our understanding of education, noting what this implies for educational practice. The paper refers to the work of Michel Foucault, discussing his ideas against the background of a distinction between education as manipulation and education as…

  8. Optical Foucault Pendulum: photons and the Coriolis effect

    NASA Astrophysics Data System (ADS)

    Rogers, Charles; Selvaggi, Richard

    2012-10-01

    Consider the motion of photons within a rotating photon clock. Will light behave as a particle as it reflects back and forth between two parallel mirrors rotating in a manner similar to the motion of a Foucault pendulum? An experiment to measure the trajectory of light in a rotating cavity is presented. Implementation details for this experiment and initial data collected are also reported.

  9. Beyond Intimaphobia: Object Lessons from Foucault and Sade

    ERIC Educational Resources Information Center

    Greteman, Adam Joseph

    2014-01-01

    In this study I suggest ways of thinking through issues of intimacy that have emerged in the late twentieth and early twenty-first centuries in the USA. I propose a state of intimaphobia in education. However, I move beyond exposing this state of intimaphobia to offer particular readings of two philosophers of intimacy: Michel Foucault and the…

  10. Evolution of the Foucault-Secretan reflecting telescope

    NASA Astrophysics Data System (ADS)

    Tobin, William

    2016-08-01

    Léon Foucault developed the silvered-glass reflecting telescope in collaboration with the instrument maker Marc Secretan. Almost immediately, they began selling 4- and 8-(French)-inch Newtonian telescopes in wooden tubes to amateurs. Several 4-inch examples have survived. As Foucault attempted to make larger diameters he moved from spherical to paraboloidal mirrors and developed tests to determine the errors of the surfaces he was polishing, of which the knife-edge test is the most informative and sensitive. The errors were then corrected with retouches locales, i.e. local repolishing. He also introduced the concept of pouvoir optique, or optical power, to characterize the performance of his mirrors. He made several professional reflecting telescopes, culminating in the 80-cm instrument now at the Marseilles Observatory. A number of his instruments are illustrated in physics textbooks of the time. Foucault predominantly adopted an f/6 focal ratio with a prism secondary close to the prime focus and a microscope-like eyepiece assembly to bring the image to the observer. In 1865, with Marc's son Auguste, Foucault announced a metal-mounted 10-cm alt-az amateur instrument, which soon became available in larger sizes and with equatorial mounts. Several examples survive. In 1866 the head of the Secretan workshop, Wilhelm Eichens, split from the firm. Marc died in 1867, followed by Foucault in 1868. Foucault's pupil Adolphe Martin published some of Foucault's mirror- and lens-making secrets. Martin worked with both Eichens and, episodically, the Secretan firm; but though able to figure small mirrors he proved incapable of finishing 80- and 120-cm ones begun under Foucault destined for the Toulouse and Paris Observatories. Auguste Secretan associated with Paul and Prosper Henry for mirror figuring. The Secretan offering of silvered-glass telescopes reached its apogee in 1874 with advertised diameters from 10 to 80 cm. Auguste died that year and the firm was taken over by

  11. Wavefront-error evaluation by mathematical analysis of experimental Foucault-test data

    NASA Technical Reports Server (NTRS)

    Wilson, R. G.

    1975-01-01

    The diffraction theory of the Foucault test provides an integral formula expressing the complex amplitude and irradiance distribution in the Foucault pattern of a test mirror (lens) as a function of wavefront error. Recent literature presents methods of inverting this formula to express wavefront error in terms of irradiance in the Foucault pattern. The present paper describes a study in which the inversion formulation was applied to photometric Foucault-test measurements on a nearly diffraction-limited mirror to determine wavefront errors for direct comparison with ones determined from scatter-plate interferometer measurements. The results affirm the practicability of the Foucault test for quantitative wavefront analysis of very small errors, and they reveal the fallacy of the prevalent belief that the test is limited to qualitative use only. Implications of the results with regard to optical testing and the potential use of the Foucault test for wavefront analysis in orbital space telescopes are discussed.

  12. Analysis of proton single-particle properties of zinc and germanium isotopes

    SciTech Connect

    Bespalova, O. V. Ermakova, T. A.; Klimochkina, A. A.; Romanovsky, E. A.; Spasskaya, T. I.

    2014-12-15

    Experimental proton single-particle energies in the vicinity of the Fermi energy for stable zinc and germanium isotopes are analyzed on the basis the dispersive optical model. The values found for the parameters of the dispersive optical potential are corrected with the aim of matching the total number of protons that is calculated with the aid of the function of Bardeen-Cooper-Schrieffer theory for the occupation probability for single-particle orbits with the charge number Z of the nucleus. The parameters of the dispersive optical potential are extrapolated on the basis of physically motivated arguments to the region of unstable isotopes in which the number N ranges between 34 and 50, and single-particle spectra are predicted by means of calculations with these parameters.

  13. Fabs enable single particle cryoEM studies of small proteins

    PubMed Central

    Wu, Shenping; Avila-Sakar, Agustin; Kim, JungMin; Booth, David S.; Greenberg, Charles H.; Rossi, Andrea; Liao, Maofu; Li, Xueming; Alian, Akram; Griner, Sarah L.; Juge, Narinobu; Yu, Yadong; Mergel, Claudia M.; Chaparro-Riggers, Javier; Strop, Pavel; Tampé, Robert; Edwards, Robert H.; Stroud, Robert M.; Craik, Charles S.; Cheng, Yifan

    2012-01-01

    Summary In spite of its recent achievements, the technique of single particle electron cryomicroscopy (cryoEM) has not been widely used to study proteins smaller than 100kDa, although it is a highly desirable application of this technique. One fundamental limitation is that images of small proteins embedded in vitreous ice do not contain adequate features for accurate image alignment. We describe a general strategy to overcome this limitation by selecting a fragment antigen binding (Fab) to form a stable and rigid complex with a target protein, thus providing a defined feature for accurate image alignment. Using this approach, we determined a three-dimensional structure of a ~65 kDa protein by single particle cryoEM. Because Fabs can be readily generated against a wide range of proteins by phage display, this approach is generally applicable to study many small proteins by single particle cryoEM. PMID:22483106

  14. Fabs enable single particle cryoEM studies of small proteins.

    PubMed

    Wu, Shenping; Avila-Sakar, Agustin; Kim, JungMin; Booth, David S; Greenberg, Charles H; Rossi, Andrea; Liao, Maofu; Li, Xueming; Alian, Akram; Griner, Sarah L; Juge, Narinobu; Yu, Yadong; Mergel, Claudia M; Chaparro-Riggers, Javier; Strop, Pavel; Tampé, Robert; Edwards, Robert H; Stroud, Robert M; Craik, Charles S; Cheng, Yifan

    2012-04-01

    In spite of its recent achievements, the technique of single particle electron cryomicroscopy (cryoEM) has not been widely used to study proteins smaller than 100 kDa, although it is a highly desirable application of this technique. One fundamental limitation is that images of small proteins embedded in vitreous ice do not contain adequate features for accurate image alignment. We describe a general strategy to overcome this limitation by selecting a fragment antigen binding (Fab) to form a stable and rigid complex with a target protein, thus providing a defined feature for accurate image alignment. Using this approach, we determined a three-dimensional structure of an ∼65 kDa protein by single particle cryoEM. Because Fabs can be readily generated against a wide range of proteins by phage display, this approach is generally applicable to study many small proteins by single particle cryoEM. PMID:22483106

  15. Improving z-tracking accuracy in the two-photon single-particle tracking microscope

    NASA Astrophysics Data System (ADS)

    Liu, C.; Liu, Y.-L.; Perillo, E. P.; Jiang, N.; Dunn, A. K.; Yeh, H.-C.

    2015-10-01

    Here, we present a method that can improve the z-tracking accuracy of the recently invented TSUNAMI (Tracking of Single particles Using Nonlinear And Multiplexed Illumination) microscope. This method utilizes a maximum likelihood estimator (MLE) to determine the particle's 3D position that maximizes the likelihood of the observed time-correlated photon count distribution. Our Monte Carlo simulations show that the MLE-based tracking scheme can improve the z-tracking accuracy of TSUNAMI microscope by 1.7 fold. In addition, MLE is also found to reduce the temporal correlation of the z-tracking error. Taking advantage of the smaller and less temporally correlated z-tracking error, we have precisely recovered the hybridization-melting kinetics of a DNA model system from thousands of short single-particle trajectories in silico. Our method can be generally applied to other 3D single-particle tracking techniques.

  16. Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

    PubMed

    Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

    2007-08-15

    Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs. PMID:17630721

  17. Improving z-tracking accuracy in the two-photon single-particle tracking microscope

    SciTech Connect

    Liu, C.; Liu, Y.-L.; Perillo, E. P.; Jiang, N.; Dunn, A. K. E-mail: tim.yeh@austin.utexas.edu; Yeh, H.-C. E-mail: tim.yeh@austin.utexas.edu

    2015-10-12

    Here, we present a method that can improve the z-tracking accuracy of the recently invented TSUNAMI (Tracking of Single particles Using Nonlinear And Multiplexed Illumination) microscope. This method utilizes a maximum likelihood estimator (MLE) to determine the particle's 3D position that maximizes the likelihood of the observed time-correlated photon count distribution. Our Monte Carlo simulations show that the MLE-based tracking scheme can improve the z-tracking accuracy of TSUNAMI microscope by 1.7 fold. In addition, MLE is also found to reduce the temporal correlation of the z-tracking error. Taking advantage of the smaller and less temporally correlated z-tracking error, we have precisely recovered the hybridization-melting kinetics of a DNA model system from thousands of short single-particle trajectories in silico. Our method can be generally applied to other 3D single-particle tracking techniques.

  18. Beyond Mean Field Study of Properties of Single-Particle States

    NASA Astrophysics Data System (ADS)

    Cao, Li-Gang; Sagawa, H.; Colò, G.; Bortignon, P. F.

    The properties of single-particle states in magic nucleus 208Pb, such as the energies, spectroscopic factors and the effective mass, have been studied with beyond mean field theory. All selected phonons are obtained by the random phase approximation (RPA) and the same Skyrme interaction is also used in the Particle-vibration coupling (PVC) vertex. We have paid more attention to the effect of the two-body spin-orbit and tensor interactions on the single-particle properties. We find that the contributions of those terms are important to improve the results. The calculated results are compared to available experimental data. The single-particle level density around the Fermi surface is significantly increased due to the effect of PVC.

  19. Foucault's legacy for nursing: are we beneficiaries or intestate heirs?

    PubMed

    Clinton, Michael E; Springer, Rusla Anne

    2016-04-01

    Drawing upon selected literature from the United Kingdom, Denmark, and Canada we examine how Foucault's concepts of 'episteme', 'rupture' 'parrhesia' 'care of the self', and 'problemitization' have been applied to particular contexts of leadership development, pedagogy, nursing knowledge, and the relationship between caring and politics. Our aims are threefold: to give examples of how selected Foucauldian concepts have been taken up in practice; to clarify how we are positioned today as nurses; and to invite more nurses to engage critically with historical inquiry and to engage in deep philosophical reflection about their relationship with nursing. We begin by examining the conditions and circumstances of Foucault's life, and conclude by posing the question in our subtitle to stimulate debate about the philosophical relevance of Foucauldian scholarship to nursing. PMID:26676822

  20. The application of single particle hydrodynamics in continuum models of multiphase flow

    NASA Technical Reports Server (NTRS)

    Decker, Rand

    1988-01-01

    A review of the application of single particle hydrodynamics in models for the exchange of interphase momentum in continuum models of multiphase flow is presented. Considered are the equations of motion for a laminar, mechanical two phase flow. Inherent to this theory is a model for the interphase exchange of momentum due to drag between the dispersed particulate and continuous fluid phases. In addition, applications of two phase flow theory to de-mixing flows require the modeling of interphase momentum exchange due to lift forces. The applications of single particle analysis in deriving models for drag and lift are examined.

  1. Interplay of Tensor Correlations and Vibrational Coupling for Nuclear Single-Particle States

    SciTech Connect

    Colo, Gianluca; Bortignon, Pier Francesco; Sagawa, Hiroyuki

    2009-08-26

    In this contribution we introduce, for the first time, a fully microscopic approach to particle-vibration coupling (PVC) based on the use of the Skyrme effective interactions. The capability of these forces to describe single-particle states in atomic nuclei, is a longstanding issue; it is certainly clear that the fragmentation of the single-particle strength lies beyond any mean field framework. After describing the formalism on which our microscopic approach is based, we discuss few preliminary results for {sup 40}Ca and {sup 208}Pb. Some perspectives are presented.

  2. Research on technique of wavefront retrieval based on Foucault test

    NASA Astrophysics Data System (ADS)

    Yuan, Lvjun; Wu, Zhonghua

    2010-05-01

    During finely grinding the best fit sphere and initial stage of polishing, surface error of large aperture aspheric mirrors is too big to test using common interferometer. Foucault test is widely used in fabricating large aperture mirrors. However, the optical path is disturbed seriously by air turbulence, and changes of light and dark zones can not be identified, which often lowers people's judging ability and results in making mistake to diagnose surface error of the whole mirror. To solve the problem, the research presents wavefront retrieval based on Foucault test through digital image processing and quantitative calculation. Firstly, real Foucault image can be gained through collecting a variety of images by CCD, and then average these image to eliminate air turbulence. Secondly, gray values are converted into surface error values through principle derivation, mathematical modeling, and software programming. Thirdly, linear deviation brought by defocus should be removed by least-square method to get real surface error. At last, according to real surface error, plot wavefront map, gray contour map and corresponding pseudo color contour map. The experimental results indicates that the three-dimensional wavefront map and two-dimensional contour map are able to accurately and intuitively show surface error on the whole mirrors under test, and they are beneficial to grasp surface error as a whole. The technique can be used to guide the fabrication of large aperture and long focal mirrors during grinding and initial stage of polishing the aspheric surface, which improves fabricating efficiency and precision greatly.

  3. [On Michel Foucault's unpublished lectures on Ludwig Binswanger's existential analysis (Lille 1953-54)].

    PubMed

    Basso, Elisabetta

    2016-12-01

    This paper aims to analyze Michel Foucault's position toward phenomenological psychology and psychopathology during the 1950s, in light of the new documentary sources available today. Our investigation is especially focused on one of the courses given by Foucault at the University of Lille between 1952 and 1954, namely, the course on "Binswanger and phenomenology" (1953-54). The analysis of this course, which was conceived by Foucault within the context of a philosophical reflection on the anthropological problem of psychopathology, will finally allow us to re-ascribe Foucault the place he deserves in the field of "philosophy of psychiatry". PMID:27550458

  4. Foucault's points of resistance. Women in science: 1620--2000

    NASA Astrophysics Data System (ADS)

    Vitale, Cindy Gail

    In his unique method of historical research, Michel Foucault was concerned with how institutional power relations are both established and maintained through discourse, in its broadest sense. Foucault found that the character of the discourse of any given period of history serves as the foundation of knowledge which is then transformed into power by those who "appropriate," "bound," then use it as "technologies of discipline." This power operates transparently and serves to "construct" individuals to meet institutional expectations. Important for this study is that Foucault believed that where there is power there is resistance, and that "points of resistance" operate everywhere in "power networks." This study has two parts. The first is a description and an extension of Foucault's notion of resistance as it operates within institutional power relations. The second, using the extended version of Foucault's resistance, is a deconstruction of the discourse of science education in the United States. The deconstruction focused on resistance operating within the male/female power relations network. The deconstruction revealed three overlapping yet distinct historical periods in which the dominant discourse was characterized by one of Foucault's three general technologies of discipline. During the first period, 1620--1790, women were generally not allowed access to formal (institutional) education. This disciplinary technology, which Foucault called "dividing practices," was justified by the commonly accepted religious view of the period that females were both mentally and morally inferior beings. Women were, so to speak, "barred at the schoolhouse gate." In the second period, 1790--1920, female resistance to these dividing practices was parallel to their limited access to formal education. Women were "admitted at the schoolhouse gate," and the appearance of successful resistance occurred as women began to enroll in science classes. Unlike their male counterparts

  5. Summary report of the group on single-particle nonlinear dynamics

    SciTech Connect

    Axinescu, S.; Bartolini, R.; Bazzani, A.

    1996-10-01

    This report summarizes the research on single-particle nonlinear beam dynamics. It discusses the following topics: analytical and semi-analytical tools; early prediction of the dynamic aperture; how the results are commonly presented; Is the mechanism of the dynamic aperture understand; ripple effects; and beam-beam effects.

  6. Single-particle electron microscopy in the study of membrane protein structure.

    PubMed

    De Zorzi, Rita; Mi, Wei; Liao, Maofu; Walz, Thomas

    2016-02-01

    Single-particle electron microscopy (EM) provides the great advantage that protein structure can be studied without the need to grow crystals. However, due to technical limitations, this approach played only a minor role in the study of membrane protein structure. This situation has recently changed dramatically with the introduction of direct electron detection device cameras, which allow images of unprecedented quality to be recorded, also making software algorithms, such as three-dimensional classification and structure refinement, much more powerful. The enhanced potential of single-particle EM was impressively demonstrated by delivering the first long-sought atomic model of a member of the biomedically important transient receptor potential channel family. Structures of several more membrane proteins followed in short order. This review recounts the history of single-particle EM in the study of membrane proteins, describes the technical advances that now allow this approach to generate atomic models of membrane proteins and provides a brief overview of some of the membrane protein structures that have been studied by single-particle EM to date. PMID:26470917

  7. A combination of size-resolved particle samplers and XRF microprobe technique for single particle study

    NASA Astrophysics Data System (ADS)

    Ma, Chang-Jin; Kim, Ki-Hyun

    It is important to understand the properties of individual airborne particulates that are determined by the processes of various physicochemical reactions occurring in their generation, transformation, and transport. This study describes the application of the X-ray fluorescence (XRF) microprobe technique to the analysis of size-resolved individual particles as well as the results of an experimental study on the comparison of three different particle collection instruments for single particle analysis: a two-stage filter pack, a low pressure Andersen impactor (LPAI), and a micro-orifice uniform deposit impactor (MOUDI). Though LPAI and MOUDI are relatively suitable for multisize-segregated particles sampling compared with the two-stage filter pack sampler, they can easily form particle clusters and finally these particle clusters impede single particle analysis. Even though more particle mass can be collected without overloading on the substrate using MOUDI, by stage rotating, particles are still deposited and form clusters on the concentric circles. When particles are forming a spot (or other shapes of particle cluster), single particle analysis using the XRF micro-beam technique is restricted to individual particles deposited at the edge of the spot. Thus, the sampling duration time depending on the sampler stage should be adjusted for single particle study.

  8. Development of a Charged Particle Microbeam for Targeted and Single Particle Subcellular Irradiation

    SciTech Connect

    Yanch, Jacquelyn C.

    2004-03-12

    The development of a charged particle microbeam for single particle, subcellular irradiations at the Massachusetts Institute of Technology Laboratory for Accelerator Beam Applications (MIT LABA) was initiated under this NEER aeard. The Microbeam apparatus makes use of a pre-existing electrostatic accelerator with a horizontal beam tube.

  9. The magic nature of 132Sn explored through the single-particle states of 133Sn

    SciTech Connect

    Jones, K. L.; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Harlin, Christopher W; Hatarik, Robert; Kapler, R.; Kozub, R. L.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Moazen, Brian; Nesaraja, Caroline D; Nunes, F. M.; Pain, S. D.; Patterson, N. P.; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.

    2010-05-01

    Atomic nuclei have a shell structure1 in which nuclei with magic numbers of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important2 5 for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in 133Sn that lies outside the double shell closure present at the short-lived nucleus 132Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of 132Sn.

  10. The magic nature of (132)Sn explored through the single-particle states of (133)Sn.

    PubMed

    Jones, K L; Adekola, A S; Bardayan, D W; Blackmon, J C; Chae, K Y; Chipps, K A; Cizewski, J A; Erikson, L; Harlin, C; Hatarik, R; Kapler, R; Kozub, R L; Liang, J F; Livesay, R; Ma, Z; Moazen, B H; Nesaraja, C D; Nunes, F M; Pain, S D; Patterson, N P; Shapira, D; Shriner, J F; Smith, M S; Swan, T P; Thomas, J S

    2010-05-27

    Atomic nuclei have a shell structure in which nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independent particles in orbitals with discrete quantum numbers, subject to a mean field generated by all the other nucleons. Knowledge of the properties of single-particle states outside nuclear shell closures in exotic nuclei is important for a fundamental understanding of nuclear structure and nucleosynthesis (for example the r-process, which is responsible for the production of about half of the heavy elements). However, as a result of their short lifetimes, there is a paucity of knowledge about the nature of single-particle states outside exotic doubly magic nuclei. Here we measure the single-particle character of the levels in (133)Sn that lie outside the double shell closure present at the short-lived nucleus (132)Sn. We use an inverse kinematics technique that involves the transfer of a single nucleon to the nucleus. The purity of the measured single-particle states clearly illustrates the magic nature of (132)Sn. PMID:20505723

  11. Geometric Phase of a Transported Oscillator

    SciTech Connect

    Dittirich, W.

    2004-02-25

    An oscillator constrained to a plane that is transported along some surface will rotate by an angle dependent only on the path and the surface, not on the speed at which it is transported. This is thus an example of a geometric phase. We analyze this phase using the methods of parallel transport. This concept plays a key role in General Relativity, but it can also be applied in classical mechanics. The Foucault pendulum can be seen as an application of this analysis, where the surface is a sphere and the curve is a line of constant latitude. In view of some considerable confusion and erroneous treatments in the recent literature, we here present a rather simple way for visualizing the motion of the Foucault pendulum using concepts that are based on Frenet's formulae and the methods of parallel displacement.

  12. Origin of macroscopic single-particle quantum behavior in Bose-Einstein-condensed systems

    NASA Astrophysics Data System (ADS)

    Mayers, J.

    2008-09-01

    It is shown that any Bose-Einstein-condensed fluid in its ground state will exhibit macroscopic single-particle quantum behavior (MSPQB). That is, (1) the many-particle wave function Ψ(r1,…,rn) factors into a single-particle product ∏nη(rn) ; (2) the function η(r) extends over macroscopic length scales and obeys the usual quantum equations for particle flux in a single-particle system; and (3) η(r) obeys a nonlinear single-particle Schrödinger equation. The latter equation reduces to the Gross-Pitaevskii equation when interactions are weak and determines the density distribution of the fluid and the time development of this distribution. The arguments used rely only on elementary concepts of probability theory and many-particle wave mechanics and are valid even in strongly interacting fluids such as superfluid He4 . It is shown that Bose-Einstein condensation implies that the N -particle wave function Ψ is delocalized. That is, if one considers a single-particle coordinate r , then for all values that occur of the other N-1 coordinates, Ψ is a nonzero function of r over a region of space proportional to V , where V is the total volume within which the fluid is contained. MSPQB is a consequence of this delocalization and the absence of long-range correlations between particle positions in fluids. The results are accurate provided that only averages over regions of space containing many particles are considered. For averages over volumes of space containing NΩ particles, inaccuracies due to quantum fluctuations are ˜1/NΩ .

  13. Quantum-information entropies for highly excited states of single-particle systems with power-type potentials

    SciTech Connect

    Dehesa, J.S.; Martinez-Finkelshtein, A.; Sorokin, V.N.

    2002-12-01

    The asymptotics of the Boltzmann-Shannon information entropy as well as the Renyi entropy for the quantum probability density of a single-particle system with a confining (i.e., bounded below) power-type potential V(x)=x{sup 2k} with k is a member of N and x is a member of R, is investigated in the position and momentum spaces within the semiclassical (WKB) approximation. It is found that for highly excited states both physical entropies, as well as their sum, have a logarithmic dependence on its quantum number not only when k=1 (harmonic oscillator), but also for any fixed k. As a by-product, the extremal case k{yields}{infinity} (the infinite well potential) is also rigorously analyzed. It is shown that not only the position-space entropy has the same constant value for all quantum states, which is a known result, but also that the momentum-space entropy is constant for highly excited states.

  14. Social Education and Mental Hygiene: Foucault, Disciplinary Technologies and the Moral Constitution of Youth

    ERIC Educational Resources Information Center

    Besley, Tina

    2002-01-01

    This paper utilises some of Foucault's notions to explore the use of the "disciplinary technologies" of film/video in social guidance programmes in schools to shape, constitute and control the morality of youth. As the first section elaborates, for Foucault, "technology" is the actual practice of power that involves "the government of individuals,…

  15. Education and/or Displacement? A Pedagogical Inquiry into Foucault's "Limit-Experience"

    ERIC Educational Resources Information Center

    Thompson, Christiane

    2010-01-01

    This paper is concerned with the educational-philosophical implications of Michel Foucault's work: It poses the question whether Michel Foucault's remarks surrounding "limit-experience" can be placed in an educational context and provide an alternative view regarding the relationship that we maintain to ourselves. As a first step, the significance…

  16. Foucault as Complexity Theorist: Overcoming the Problems of Classical Philosophical Analysis

    ERIC Educational Resources Information Center

    Olssen, Mark

    2008-01-01

    This article explores the affinities and parallels between Foucault's Nietzschean view of history and models of complexity developed in the physical sciences in the twentieth century. It claims that Foucault's rejection of structuralism and Marxism can be explained as a consequence of his own approach which posits a radical ontology whereby the…

  17. Problematizing the "Taken for Granted" in Educational Issues: Karl Marx, Antonio Gramsci, and Michel Foucault.

    ERIC Educational Resources Information Center

    Qi, Jie

    This paper explores how educators would raise different questions about educational issues by using Karl Marx's framework, Antonio Gramsci's conception, and Michel Foucault's notions, respectively. First, the paper compares the historical perspectives of Marx and Foucault. Marx concludes that history is a progressive linear production and that…

  18. Foucault, Governmentality, Neoliberalism and Adult Education--Perspective on the Normalization of Social Risks

    ERIC Educational Resources Information Center

    Kopecký, Martin

    2011-01-01

    The article deals with the relevance of the work of Foucault to critical analysis of the political concept of lifelong learning that currently dominates. This concept relates to the field of adult education and learning. The article makes reference to the relatively late incorporation of Foucault's work within andragogy. It shows the…

  19. Truth, Power and Pedagogy: Michel Foucault on the Rise of the Disciplines

    ERIC Educational Resources Information Center

    Deacon, Roger

    2002-01-01

    Michel Foucault sought to understand how and why it is that people in the West, in their arduous and incessant search for truth, have also built into and around themselves intricate and powerful systems intended to manage all that they know and do. While little of Foucault's work directly concerns itself with the historically recent phenomenon of…

  20. The Product of Text and "Other" Statements: Discourse Analysis and the Critical Use of Foucault

    ERIC Educational Resources Information Center

    Graham, Linda J.

    2011-01-01

    Much has been written on Michel Foucault's reluctance to clearly delineate a research method, particularly with respect to genealogy (Harwood, 2000; Meadmore, Hatcher & McWilliam, 2000; Tamboukou, 1999). Foucault (1994, p. 288) himself disliked prescription stating, "I take care not to dictate how things should be" and wrote provocatively to…

  1. Structuralism, Post-Structuralism, and Neo-Liberalism: Assessing Foucault's Legacy.

    ERIC Educational Resources Information Center

    Olssen, Mark

    2003-01-01

    Traces Foucault's distinctive commitment to "post-structuralism." Argues that under the influence of Nietzsche, Foucault's approach marks a distinct break with structuralism in several crucial aspects. What results is a materialist post-structuralism that is also distinctively different from the post-structuralism of Derrida, Lyotard, and…

  2. Individual perception and cultural development: Foucault's 1954 approach to mental illness and its history.

    PubMed

    Joranger, Line

    2016-02-01

    In his 1954 book Mental Illness and Personality Foucault combines the subjective experience of the mentally ill person with a sociocultural historical approach to mental illness and suggests that there exists a reciprocal connection between individual perception and sociocultural development. This article examines the ramifications of these connections in Foucault's 1954 works and the connection with his later historical works. The article also examines the similarities between Foucault's 1954 thoughts and contemporary intellectual thought, such as those outlined in Maurice Merleau-Ponty's existential phenomenology and in Gaston Bachelard and Georges Canguilhem's historical epistemology. In sum, my study shows that Foucault's historical analysis began long before his 1961 dissertation History of Madness. It also shows that, more than announcing the "death" of the subject, Foucault's historical analysis may have contributed to saving it. PMID:26844650

  3. Note: A 1-m Foucault pendulum rolling on a ball

    NASA Astrophysics Data System (ADS)

    Salva, H. R.; Benavides, R. E.; Venturino, J. A.; Cuscueta, D. J.; Ghilarducci, A. A.

    2013-10-01

    We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.

  4. Two often disregarded aspects of Foucaultʼs pendulum

    NASA Astrophysics Data System (ADS)

    Pérez, José-Philippe; Pujol, Olivier

    2015-01-01

    This paper revisits the famous Foucault's pendulum by highlighting two often-disregarded aspects in mechanics courses. The first one concerns the existence of a local accelerated reference frame to express the law of dynamics without the Coriolis force. The second aspect deals with the geometrical phase that appears in pendulum dynamics. This last point, which could appear banal, should be related to analogous consideration in quantum physics. It is also linked to vectorial parallel transport of the pendulum angular momentum eigenvector. Numerical simulations with MATLAB are proposed.

  5. Radiative capture of nucleons at astrophysical energies with single-particle states

    SciTech Connect

    Huang, J.T.; Bertulani, C.A.; Guimaraes, V.

    2010-11-15

    Radiative capture of nucleons at energies of astrophysical interest is one of the most important processes for nucleosynthesis. The nucleon capture can occur either by a compound nucleus reaction or by a direct process. The compound reaction cross sections are usually very small, especially for light nuclei. The direct capture proceeds either via the formation of a single-particle resonance or a non-resonant capture process. In this work we calculate radiative capture cross sections and astrophysical S-factors for nuclei in the mass region A<20 using single-particle states. We carefully discuss the parameter fitting procedure adopted in the simplified two-body treatment of the capture process. Then we produce a detailed list of cases for which the model works well. Useful quantities, such as spectroscopic factors and asymptotic normalization coefficients, are obtained and compared to published data.

  6. Guidelines for the fitting of anomalous diffusion mean square displacement graphs from single particle tracking experiments.

    PubMed

    Kepten, Eldad; Weron, Aleksander; Sikora, Grzegorz; Burnecki, Krzysztof; Garini, Yuval

    2015-01-01

    Single particle tracking is an essential tool in the study of complex systems and biophysics and it is commonly analyzed by the time-averaged mean square displacement (MSD) of the diffusive trajectories. However, past work has shown that MSDs are susceptible to significant errors and biases, preventing the comparison and assessment of experimental studies. Here, we attempt to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes. We extract the precision and accuracy of the fitted MSD for various anomalous exponents and measurement errors with respect to measurement length and maximum time lags. Based on the calculated precision maps, we present guidelines to improve accuracy in single particle studies. Importantly, we find that in some experimental conditions, the time averaged MSD should not be used as an estimator. PMID:25680069

  7. Single particle electron cryo-microscopy of a mammalian ion channel

    PubMed Central

    Liao, Maofu; Cao, Erhu; Julius, David; Cheng, Yifan

    2014-01-01

    The transient receptor potential (TRP) ion channel family is large and functionally diverse, second only to potassium channels. Despite their prominence within the animal kingdom, TRP channels have resisted crystallization and structural determination for many years. This barrier was recently broken when the three-dimensional structure of the vanilloid receptor 1 (TRPV1) was determined by single particle electron cryo-microscopy (cryo-EM). Moreover, this is the first example in which the near atomic resolution structure of an integral membrane protein was elucidated by this technique and in a manner not requiring crystals, demonstrating the transformative power of single particle cryo-EM for revealing high-resolution structures of integral membrane proteins, particularly those of mammalian origin. Here we summarize technical advances, in both biochemistry and cryo-EM, that led to this major breakthrough. PMID:24681231

  8. Inequivalence of single-particle and population lifetimes in a cuprate superconductor

    SciTech Connect

    Yang, Shuolong; Sobota, J. A.; Leuenberger, D.; He, Y.; Hashimoto, M.; Lu, D. H.; Eisaki, H.; Kirchmann, P. S.; Shen, Z. -X.

    2015-06-15

    We study optimally doped Bi-2212 (Tc=96 K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1–2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. As a result, the qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors.

  9. Detecting gamma-ray bursts with the pierre auger observatory using the single particle technique

    SciTech Connect

    Allard, Denis; Parizot, E.; Bertou, Xavier; Beatty, J.; Vernois, M.Du; Nitz, D.; Rodriguez, G.

    2005-08-01

    During the past ten years, gamma-ray Bursts (GRB) have been extensively studied in the keV-MeV energy range but the higher energy emission still remains mysterious. Ground based observatories have the possibility to investigate energy range around one GeV using the ''single particle technique''. The aim of the present study is to investigate the capability of the Pierre Auger Observatory to detect the high energy emission of GRBs with such a technique. According to the detector response to photon showers around one GeV, and making reasonable assumptions about the high energy emission of GRBs, we show that the Pierre Auger Observatory is a competitive instrument for this technique, and that water tanks are very promising detectors for the single particle technique.

  10. Entanglement classification of three fermions with up to nine single-particle states

    NASA Astrophysics Data System (ADS)

    Sárosi, Gábor; Lévay, Péter

    2014-04-01

    Based on results well known in the mathematics literature but not yet common knowledge in the physics literature, we conduct a study on three-fermionic systems with six, seven, eight, and nine single-particle states. Via introducing special polynomial invariants playing the role of entanglement measures the structure of the stochastic local operations and classical communication (SLOCC) entanglement classes is investigated. The SLOCC classes of the six- and seven-dimensional cases can elegantly be described by special subconfigurations of the Fano plane. Some special embedded systems containing distinguishable constituents are arising naturally in our formalism, namely, three-qubits and three-qutrits. In particular, the three fundamental invariants I6, I9, and I12 of the three-qutrits system are shown to arise as special cases of the four fundamental invariants of three-fermions with nine single-particle states.

  11. Single Particle Tracking Reveals Biphasic Transport During Nanorod Magnetophoresis Through Extracellular Matrix

    PubMed Central

    Mair, L.O.; Superfine, R.

    2014-01-01

    Magnetic drug targeting has been proposed as a means of efficiently targeting drugs to tumors. However, the extracellular matrix (ECM) remains a significant barrier to long-range magnetophoretic transport through the tumor volume. While ensemble measurements of nanoparticle magnetophoresis have been reported, a single particle level understanding of magnetophoretic transport remains at large. We quantify nanorod magnetophoresis through ECM based on single particle observations. We find that smaller diameter particles achieve larger velocities through ECM despite experiencing smaller magnetic forces. Additionally, two interesting dynamics are elucidated. First, 18 nm diameter nanorods experience bimodal stick-slip motion through ECM during static field magnetophoresis, while similar bimodal transport is not observed for 55 nm nor 200 nm diameter nanorods. Second, smaller particles experience larger deviations in their orientation angle with respect to the magnetic field. This work elucidates important dynamics of nanoparticle transport through complex, porous biomaterials that may go unnoticed during ensemble measurements. PMID:24744160

  12. Cryo-EM single particle analysis with the Volta phase plate

    PubMed Central

    Danev, Radostin; Baumeister, Wolfgang

    2016-01-01

    We present a method for in-focus data acquisition with a phase plate that enables near-atomic resolution single particle reconstructions. Accurate focusing is the determining factor for obtaining high quality data. A double-area focusing strategy was implemented in order to achieve the required precision. With this approach we obtained a 3.2 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome. The phase plate matches or slightly exceeds the performance of the conventional defocus approach. Spherical aberration becomes a limiting factor for achieving resolutions below 3 Å with in-focus phase plate images. The phase plate could enable single particle analysis of challenging samples in terms of small size, heterogeneity and flexibility that are difficult to solve by the conventional defocus approach. DOI: http://dx.doi.org/10.7554/eLife.13046.001 PMID:26949259

  13. Temperature and momentum dependence of single-particle properties in hot asymmetric nuclear matter

    SciTech Connect

    Moustakidis, Ch. C.

    2008-11-15

    We have studied the effects of momentum-dependent interactions on the single-particle properties of hot asymmetric nuclear matter. In particular, the single-particle potential of protons and neutrons as well as the symmetry potential have been studied within a self-consistent model using a momentum-dependent effective interaction. In addition, the isospin splitting of the effective mass has been derived from the above model. In each case temperature effects have been included and analyzed. The role of the specific parametrization of the effective interaction used in the present work has been investigated. It has been concluded that the behavior of the symmetry potential depends strongly on the parametrization of the interaction part of the energy density and the momentum dependence of the regulator function. The effects of the parametrization have been found to be less pronounced on the isospin mass splitting.

  14. Guidelines for the Fitting of Anomalous Diffusion Mean Square Displacement Graphs from Single Particle Tracking Experiments

    PubMed Central

    Kepten, Eldad; Weron, Aleksander; Sikora, Grzegorz; Burnecki, Krzysztof; Garini, Yuval

    2015-01-01

    Single particle tracking is an essential tool in the study of complex systems and biophysics and it is commonly analyzed by the time-averaged mean square displacement (MSD) of the diffusive trajectories. However, past work has shown that MSDs are susceptible to significant errors and biases, preventing the comparison and assessment of experimental studies. Here, we attempt to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes. We extract the precision and accuracy of the fitted MSD for various anomalous exponents and measurement errors with respect to measurement length and maximum time lags. Based on the calculated precision maps, we present guidelines to improve accuracy in single particle studies. Importantly, we find that in some experimental conditions, the time averaged MSD should not be used as an estimator. PMID:25680069

  15. Single particle and collective orientational relaxation in an anisotropic liquid near the isotropic-nematic transition

    NASA Astrophysics Data System (ADS)

    Perera, A.; Ravichandran, S.; Moreau, M.; Bagchi, B.

    1997-01-01

    We report molecular dynamics simulation results for the single particle and collective orientational correlations for Gay-Berne fluid of anisotropy parameters κ=3 and κ=5. The following significant results are reported. (i) The decay of collective orientational relaxation of rank two is found to slow down appreciably while approaching the isotropic-nematic (I-N) transition. It eventually becomes even slower than the single particle orientational relaxation of rank one. Surprisingly, even the latter shows a marked slowing down near the I-N transition. (ii) Analysis of the long-time behavior shows a breakdown of the rank dependence predicted by the Debye law in the same region. (iii) An analysis of the memory functions of the orientational time-correlation functions shows that for the collective relaxation surprisingly approaches a Markovian behavior near the I-N transition.

  16. Cryo-EM single particle analysis with the Volta phase plate.

    PubMed

    Danev, Radostin; Baumeister, Wolfgang

    2016-01-01

    We present a method for in-focus data acquisition with a phase plate that enables near-atomic resolution single particle reconstructions. Accurate focusing is the determining factor for obtaining high quality data. A double-area focusing strategy was implemented in order to achieve the required precision. With this approach we obtained a 3.2 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome. The phase plate matches or slightly exceeds the performance of the conventional defocus approach. Spherical aberration becomes a limiting factor for achieving resolutions below 3 Å with in-focus phase plate images. The phase plate could enable single particle analysis of challenging samples in terms of small size, heterogeneity and flexibility that are difficult to solve by the conventional defocus approach. PMID:26949259

  17. Testing the Validity of Single-Particle Maps at Low and High Resolution.

    PubMed

    Rosenthal, P B

    2016-01-01

    Single-particle electron cryomicroscopy may be used to determine the structure of biological assemblies by aligning and averaging low-contrast projection images recorded in the electron microscope. Recent progress in both experimental and computational methods has led to higher resolution three-dimensional maps, including for more challenging low molecular weight proteins, and this has highlighted the problems of model bias and over-fitting during iterative refinement that can potentially lead to incorrect map features at low or high resolution. This chapter discusses the principles and practice of specific validation tests that demonstrate the consistency of a 3D map with projection images. In addition, the chapter describes tests that detect over-fitting during refinement and lead to more robust assessment of both global and local map resolution. Application of several of these tests together demonstrates the reliability of single-particle maps that underpins their correct biological interpretation. PMID:27572729

  18. Collective ion diffusion and localized single particle dynamics in pyridinium-based ionic liquids.

    PubMed

    Burankova, Tatsiana; Hempelmann, Rolf; Wildes, Andrew; Embs, Jan P

    2014-12-11

    Quasielastic neutron scattering with polarized neutrons allows for an experimental separation of single-particle and collective processes, as contained in the incoherent and coherent scattering contributions. This technique was used to investigate the dynamical processes in the pyridinium-based ionic liquid 1-butylpyridinium bis(trifluoromethylsulfonyl)-imide. We observed two diffusion processes with different time scales. The slower diffusional process was present in both the coherent and the incoherent contribution, meaning that this process has at least a partial collective nature. The second faster localized process is only present in the incoherent scattering contribution. We conclude that it is a true single-particle process on a shorter time scale. PMID:25387035

  19. Single-particle versus pair superfluidity in a bilayer system of dipolar bosons

    NASA Astrophysics Data System (ADS)

    Macia, A.; Astrakharchik, G. E.; Mazzanti, F.; Giorgini, S.; Boronat, J.

    2014-10-01

    We consider the ground state of a bilayer system of dipolar bosons, where dipoles are oriented by an external field in the direction perpendicular to the parallel planes. Quantum Monte Carlo methods are used to calculate the ground-state energy, the one-body and two-body density matrix, and the superfluid response as a function of the separation between layers. We find that by decreasing the interlayer distance for fixed value of the strength of the dipolar interaction, the system undergoes a quantum phase transition from a single-particle to a pair superfluid. The single-particle superfluid is characterized by a finite value of both the atomic condensate and the super-counterfluid density. The pair superfluid phase is found to be stable against formation of many-body cluster states and features a gap in the spectrum of elementary excitations.

  20. Inequivalence of Single-Particle and Population Lifetimes in a Cuprate Superconductor.

    PubMed

    Yang, S-L; Sobota, J A; Leuenberger, D; He, Y; Hashimoto, M; Lu, D H; Eisaki, H; Kirchmann, P S; Shen, Z-X

    2015-06-19

    We study optimally doped Bi-2212 (T(c)=96  K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1-2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. The qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors. PMID:26196996

  1. Digital atom interferometer with single particle control on a discretized space-time geometry

    PubMed Central

    Steffen, Andreas; Alberti, Andrea; Alt, Wolfgang; Belmechri, Noomen; Hild, Sebastian; Karski, Michał; Widera, Artur; Meschede, Dieter

    2012-01-01

    Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 × 10-4 in units of gravitational acceleration g. PMID:22665771

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  3. Single-particle light-scattering measurement: photochemical aerosols and atmospheric particulates.

    PubMed

    Phillips, D T; Wyatt, P J

    1972-09-01

    The use of single-particle light-scattering measurements to determine the origin of atmospheric hazes has been explored by measurement of laboratory aerosols, field samples, and computer analysis of the light-scattering data. The refractive index of measured spherical particles 800 nm to 1000 nm in diameter was determined within 2%. For particles of diameter less than 500 nm the measurement of absolute scattering intensity is required for complete analysis. Distinctive nonspherical and absorbing particles were observed both in automotive exhaust and atmospheric samples. Electrostatic suspension of atmospheric particulates is demonstrated to provide a practical approach to optical measurement of single particles. The technique may be used to calibrate optical particle counters or identify particles with unique shape or refractive index. PMID:20119285

  4. Green's function method for single-particle resonant states in relativistic mean field theory

    NASA Astrophysics Data System (ADS)

    Sun, T. T.; Zhang, S. Q.; Zhang, Y.; Hu, J. N.; Meng, J.

    2014-11-01

    Relativistic mean field theory is formulated with the Green's function method in coordinate space to investigate the single-particle bound states and resonant states on the same footing. Taking the density of states for free particles as a reference, the energies and widths of single-particle resonant states are extracted from the density of states without any ambiguity. As an example, the energies and widths for single-neutron resonant states in 120Sn are compared with those obtained by the scattering phase-shift method, the analytic continuation in the coupling constant approach, the real stabilization method, and the complex scaling method. Excellent agreements with these methods are found for the energies and widths of single-neutron resonant states.

  5. Topological invariants for interacting topological insulators. II. Breakdown of single-particle Green's function formalism

    NASA Astrophysics Data System (ADS)

    He, Yuan-Yao; Wu, Han-Qing; Meng, Zi Yang; Lu, Zhong-Yi

    2016-05-01

    Topological phase transitions in free fermion systems can be characterized by the closing of single-particle gap and the change in topological invariants. However, in the presence of electronic interactions, topological phase transitions can be more complicated. In paper I of this series [Phys. Rev. B 93, 195163 (2016), 10.1103/PhysRevB.93.195163], we have proposed an efficient scheme to evaluate the topological invariants based on the single-particle Green's function formalism. Here, in paper II, we demonstrate several interaction-driven topological phase transitions (TPTs) in two-dimensional (2D) interacting topological insulators (TIs) via large-scale quantum Monte Carlo (QMC) simulations, based on the scheme of evaluating topological invariants presented in paper I. Across these transitions, the defining symmetries of the TIs have been neither explicitly nor spontaneously broken. In the first two models, the topological invariants calculated from the Green's function formalism succeed in characterizing the topologically distinct phases and identifying interaction-driven TPTs. However, in the other two models, we find that the single-particle gap does not close and the topological invariants constructed from the single-particle Green's function acquire no change across the TPTs. Unexpected breakdown of the Green's function formalism in constructing the topological invariants is thus discovered. We thence classify the topological phase transitions in interacting TIs into two categories in practical computation: Those that have noninteracting correspondence can be characterized successfully by the topological invariants constructed from the Green's functions, while for the others that do not have noninteracting correspondence, the Green's function formalism experiences a breakdown, but more interesting and exciting phenomena, such as emergent collective critical modes at the transition, arise. Discussion on the success and breakdown of topological invariants

  6. Study of dipole excitations and the single particle structure of neutron rich Ni isotopes

    NASA Astrophysics Data System (ADS)

    Mahata, K.; Paschalis, S.; Adrich, P.; Aksouh, F.; Aumann, T.; Babilon, M.; Behr, K.-H.; Benlliure, J.; Berg, T.; Boehmer, M.; Boretzky, K.; Brünle, A.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. Datta; Deveaux, L.; Elvers, M.; Emling, H.; Fernandez-Dominguez, B.; Gorska, M.; Hüller, W.; Ickert, G.; Johansson, H.; Junghans, A.; Karagiannis, C.; Kern, L.; Kiselev, O.; Klimkiewicz, A.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Lindenberg, K.; Litvinov, Y.; Maierbeck, P.; Müller, S.; Nilsson, T.; Nociforo, C.; Palit, R.; Prokopowicz, W.; Rossi, D.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

    2008-05-01

    An experiment was performed using the FRS-LAND setup at GSI to study the dipole strength distributions above neutron separation threshold for neutron-rich Ni isotopes. Measurements, using the same experimental setup, were also carried out to extract single particle occupancies via knockout reactions to investigate the structure and magicity of the neutron-rich Ni isotopes. The status of the data analysis and preliminary results are presented.

  7. NA49 Results on Single Particle and Correlation Measurements in Central PB+PB Collisions

    SciTech Connect

    Wang, F.

    1998-12-01

    Single-particle spectra and two-particle correlation functions measured by the NA49 collaboration in central Pb+Pb collisions at 158 GeV/nucleon are presented. These measurements are used to study the kinetic and chemical freeze-out conditions in heavy ion collisions. We conclude that large baryon stopping, high baryon density and strong transverse radial flow are achieved in central Pb+Pb collisions at the SPS.

  8. Teleportation of three-dimensional single particle state in noninertial frames

    NASA Astrophysics Data System (ADS)

    Wu, Qi-Cheng; Wen, Jing-Ji; Ji, Xin; Yeon, Kyu-Hwang

    2014-02-01

    Considering the spin degree of freedom of the Dirac field, we study the entanglement behavior of a different class of communication channel and teleportation of three-dimensional single particle state in noninertial frames. Numerical analysis shows that the communication channel in our scheme can offer enough distillable entanglement for the teleportation protocol. Moreover, the teleportation protocol could work well if Rob's acceleration is not very big, but the fidelity of the teleportation is still reduced due to the Unruh effect.

  9. Single-particle cryo-EM data acquisition by using direct electron detection camera.

    PubMed

    Wu, Shenping; Armache, Jean-Paul; Cheng, Yifan

    2016-02-01

    Recent advances in single-particle electron cryo-microscopy (cryo-EM) were largely facilitated by the application of direct electron detection cameras. These cameras feature not only a significant improvement in detective quantum efficiency but also a high frame rate that enables images to be acquired as 'movies' made of stacks of many frames. In this review, we discuss how the applications of direct electron detection cameras in cryo-EM have changed the way the data are acquired. PMID:26546989

  10. Single Particle ICP-MS: Advances toward routine analysis of nanomaterials.

    PubMed

    Montaño, Manuel D; Olesik, John W; Barber, Angela G; Challis, Katie; Ranville, James F

    2016-07-01

    From its early beginnings in characterizing aerosol particles to its recent applications for investigating natural waters and waste streams, single particle inductively coupled plasma-mass spectrometry (spICP-MS) has proven to be a powerful technique for the detection and characterization of aqueous dispersions of metal-containing nanomaterials. Combining the high-throughput of an ensemble technique with the specificity of a single particle counting technique and the elemental specificity of ICP-MS, spICP-MS is capable of rapidly providing researchers with information pertaining to size, size distribution, particle number concentration, and major elemental composition with minimal sample perturbation. Recently, advances in data acquisition, signal processing, and the implementation of alternative mass analyzers (e.g., time-of-flight) has resulted in a wider breadth of particle analyses and made significant progress toward overcoming many of the challenges in the quantitative analysis of nanoparticles. This review provides an overview of spICP-MS development from a niche technique to application for routine analysis, a discussion of the key issues for quantitative analysis, and examples of its further advancement for analysis of increasingly complex environmental and biological samples. Graphical Abstract Single particle ICP-MS workflow for the analysis of suspended nanoparticles. PMID:27334719

  11. Theoretical analysis of the single-particle states in the secondary minima of fissioning nuclei

    NASA Astrophysics Data System (ADS)

    Dudek, J.; Nazarewicz, W.; Faessler, A.

    1984-01-01

    The structure of the single-particle levels in the secondary minima of fissioning nuclei is analysed with the help of the deformed Woods-Saxon potential. The parametrisation of the spin-orbit part of the potential at large elongations is analysed in detail. A set of parameters is found which reproduces simultaneously results of the g-factor measurements for 239mPu, 237mpu and 239mAm, the data on single-particle resonances in the secondary minima of 231Th, 233Th, and which also gives rise to a significant energy gap at the neutron magic number N0 = 146 ( ΔE~ 1.3 MeV). The structure of the single-particle states around N0 = 146 is analysed and the results are compared with the existing experimental information. The total enegy surfaces are recalculated with the new-found parametrisation of the potential; an overall improvement of the barrier characteristics is found. Decoupling parameters and g-factors are tabulated for deformations corresponding to the secondary minima.

  12. Electron Cryomicroscopy of Membrane Proteins: Specimen Preparation for Two-Dimensional Crystals and Single Particles

    PubMed Central

    Schmidt-Krey, Ingeborg; Rubinstein, John L.

    2010-01-01

    Membrane protein structure and function can be studied by two powerful and highly complementary electron cryomicroscopy (cryo-EM) methods: electron crystallography of two-dimensional (2D) crystals and single particle analysis of detergent-solubilized protein complexes. To obtain the highest-possible resolution data from membrane proteins, whether prepared as 2D crystals or single particles, cryo-EM samples must be vitrified with great care. Grid preparation for cryo-EM of 2D crystals is possible by back-injection, the carbon sandwich technique, drying in sugars before cooling in the electron microscope, or plunge-freezing. Specimen grids for single particle cryo-EM studies of membrane proteins are usually produced by plunge-freezing protein solutions, supported either by perforated or a continuous carbon film substrate. This review outlines the different techniques available and the suitability of each method for particular samples and studies. Experimental considerations in sample preparation and preservation include the protein itself and the presence of lipid or detergent. The appearance of cryo-EM samples in different conditions is also discussed. PMID:20678942

  13. Single-particle structure determination by X-ray free-electron lasers: Possibilities and challenges

    PubMed Central

    Hosseinizadeh, A.; Dashti, A.; Schwander, P.; Fung, R.; Ourmazd, A.

    2015-01-01

    Single-particle structure recovery without crystals or radiation damage is a revolutionary possibility offered by X-ray free-electron lasers, but it involves formidable experimental and data-analytical challenges. Many of these difficulties were encountered during the development of cryogenic electron microscopy of biological systems. Electron microscopy of biological entities has now reached a spatial resolution of about 0.3 nm, with a rapidly emerging capability to map discrete and continuous conformational changes and the energy landscapes of biomolecular machines. Nonetheless, single-particle imaging by X-ray free-electron lasers remains important for a range of applications, including the study of large “electron-opaque” objects and time-resolved examination of key biological processes at physiological temperatures. After summarizing the state of the art in the study of structure and conformations by cryogenic electron microscopy, we identify the primary opportunities and challenges facing X-ray-based single-particle approaches, and possible means for circumventing them. PMID:26798800

  14. EMAN: semiautomated software for high-resolution single-particle reconstructions.

    PubMed

    Ludtke, S J; Baldwin, P R; Chiu, W

    1999-12-01

    We present EMAN (Electron Micrograph ANalysis), a software package for performing semiautomated single-particle reconstructions from transmission electron micrographs. The goal of this project is to provide software capable of performing single-particle reconstructions beyond 10 A as such high-resolution data become available. A complete single-particle reconstruction algorithm is implemented. Options are available to generate an initial model for particles with no symmetry, a single axis of rotational symmetry, or icosahedral symmetry. Model refinement is an iterative process, which utilizes classification by model-based projection matching. CTF (contrast transfer function) parameters are determined using a new paradigm in which data from multiple micrographs are fit simultaneously. Amplitude and phase CTF correction is then performed automatically as part of the refinement loop. A graphical user interface is provided, so even those with little image processing experience will be able to begin performing reconstructions. Advanced users can directly use the lower level shell commands and even expand the package utilizing EMAN's extensive image-processing library. The package was written from scratch in C++ and is provided free of charge on our Web site. We present an overview of the package as well as several conformance tests with simulated data. PMID:10600563

  15. Foucault dissipation in a rolling cylinder: a webcam quantitative study

    NASA Astrophysics Data System (ADS)

    Bonanno, A.; Bozzo, G.; Camarca, M.; Sapia, P.

    2011-03-01

    In this paper we present an experimental strategy to measure the micro power dissipation due to Foucault 'eddy' currents in a copper cylinder rolling on two parallel conductive rails in the presence of a magnetic field. Foucault power dissipation is obtained from kinematical measurements carried out by using a common PC webcam and video analysis done by means of software tools freely available within Windows operating system (Paint and Movie Maker). The proposed method allows us to experimentally discern the contribution to dissipation due to the velocity-independent rolling friction from that owed to the viscous-like friction emerging from complex electrodynamic interactions among eddy currents and the external magnetic field. In this way a microdissipation of some tens of µW is measured. The easily reproducible experimental setup, the simple implementation of data analysis and the discussion on various experimental approaches and strategies make the proposed activity highly significant for university undergraduates, since involved crucial skills can be efficiently strengthened.

  16. Single Particle Electron Microscopy Reconstruction of the Exosome Complex Using the Random Conical Tilt Method

    PubMed Central

    Liu, Xueqi; Wang, Hong-Wei

    2011-01-01

    Single particle electron microscopy (EM) reconstruction has recently become a popular tool to get the three-dimensional (3D) structure of large macromolecular complexes. Compared to X-ray crystallography, it has some unique advantages. First, single particle EM reconstruction does not need to crystallize the protein sample, which is the bottleneck in X-ray crystallography, especially for large macromolecular complexes. Secondly, it does not need large amounts of protein samples. Compared with milligrams of proteins necessary for crystallization, single particle EM reconstruction only needs several micro-liters of protein solution at nano-molar concentrations, using the negative staining EM method. However, despite a few macromolecular assemblies with high symmetry, single particle EM is limited at relatively low resolution (lower than 1 nm resolution) for many specimens especially those without symmetry. This technique is also limited by the size of the molecules under study, i.e. 100 kDa for negatively stained specimens and 300 kDa for frozen-hydrated specimens in general. For a new sample of unknown structure, we generally use a heavy metal solution to embed the molecules by negative staining. The specimen is then examined in a transmission electron microscope to take two-dimensional (2D) micrographs of the molecules. Ideally, the protein molecules have a homogeneous 3D structure but exhibit different orientations in the micrographs. These micrographs are digitized and processed in computers as "single particles". Using two-dimensional alignment and classification techniques, homogenous molecules in the same views are clustered into classes. Their averages enhance the signal of the molecule's 2D shapes. After we assign the particles with the proper relative orientation (Euler angles), we will be able to reconstruct the 2D particle images into a 3D virtual volume. In single particle 3D reconstruction, an essential step is to correctly assign the proper orientation

  17. Single-particle blocking and collective magnetic states in discontinuous CoFe/Al2O3 multilayers

    NASA Astrophysics Data System (ADS)

    Bedanta, S.; Petracic, O.; Chen, X.; Rhensius, J.; Bedanta, S.; Kentzinger, E.; Rücker, U.; Brückel, T.; Doran, A.; Scholl, A.; Cardoso, S.; Freitas, P. P.; Kleemann, W.

    2010-12-01

    Discontinuous metal-insulator multilayers (DMIMs) of [CoFe(tn)/Al2O3]m containing soft ferromagnetic (FM) Co80Fe20 nanoparticles embedded discontinuously in a diamagnetic insulating Al2O3 matrix are ideal systems to study interparticle interaction effects. Here the CoFe nanoparticles are treated as superspins with random size, position and anisotropy. At low particle density, namely nominal layer thickness tn = 0.5 nm, single-particle blocking phenomena are observed due to the absence of large enough interparticle interactions. However at 0.5 nm < tn < 1.1 nm, the particles encounter strong interactions which give rise to a superspin glass (SSG) phase. The SSG phase has been characterized by memory effect, ageing, dynamic scaling, etc. With further increase in particle concentration (1.1 nm < tn < 1.4 nm) and, hence, smaller interparticle distances, strong interactions lead to a FM-like state which is called superferromagnetic (SFM). The SFM state has been characterized by several techniques, e.g. dynamic hysteresis, Cole-Cole plots extracted from ac susceptibility, polarized neutron reflectometry, etc. Moreover, the SFM domains could be imaged by x-ray photoemission electron microscopy and magneto-optic Kerr effect microscopy. At tn > 1.4 nm physical percolation occurs between the particles and the samples are no longer discontinuous and then termed as metal insulating multilayers. Competition between long- and short-ranged dipolar interactions leads to an oscillating magnetization depth profile from CoFe layer to CoFe layer with an incommensurate periodicity.

  18. SIMPLE: Software for ab initio reconstruction of heterogeneous single-particles.

    PubMed

    Elmlund, Dominika; Elmlund, Hans

    2012-12-01

    The open source software suite SIMPLE: Single-particle IMage Processing Linux Engine provides data analysis methods for single-particle cryo-electron microscopy (cryo-EM). SIMPLE addresses the problem of obtaining 3D reconstructions from 2D projections only, without using an input reference volume for approximating orientations. The SIMPLE reconstruction algorithm is tailored to asymmetrical and structurally heterogeneous single-particles. Its basis is global optimization with the use of Fourier common lines. The advance that enables ab initio reconstruction and heterogeneity analysis is the separation of the tasks of in-plane alignment and projection direction determination via bijective orientation search - a new concept in common lines-based strategies. Bijective orientation search divides the configuration space into two groups of paired parameters that are optimized separately. The first group consists of the rotations and shifts in the plane of the projection; the second group consists of the projection directions and state assignments. In SIMPLE, ab initio reconstruction is feasible because the 3D in-plane alignment is approximated using reference-free 2D rotational alignment. The subsequent common lines-based search hence searches projection directions and states only. Thousands of class averages are analyzed simultaneously in a matter of hours. Novice SIMPLE users get a head start via the well documented front-end. The structured, object-oriented back-end invites advanced users to develop new alignment and reconstruction algorithms. An overview of the package is presented together with benchmarks on simulated data. Executable binaries, source code, and documentation are available at http://simple.stanford.edu. PMID:22902564

  19. In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Harris, E.; Sinha, B.; van Pinxteren, D.; Schneider, J.; Poulain, L.; Collett, J.; D'Anna, B.; Fahlbusch, B.; Foley, S.; Fomba, K. W.; George, C.; Gnauk, T.; Henning, S.; Lee, T.; Mertes, S.; Roth, A.; Stratmann, F.; Borrmann, S.; Hoppe, P.; Herrmann, H.

    2014-01-01

    In-cloud production of sulfate modifies the aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in Autumn, 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4(g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4(g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.

  20. In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010

    NASA Astrophysics Data System (ADS)

    Harris, E.; Sinha, B.; van Pinxteren, D.; Schneider, J.; Poulain, L.; Collett, J.; D'Anna, B.; Fahlbusch, B.; Foley, S.; Fomba, K. W.; George, C.; Gnauk, T.; Henning, S.; Lee, T.; Mertes, S.; Roth, A.; Stratmann, F.; Borrmann, S.; Hoppe, P.; Herrmann, H.

    2014-04-01

    In-cloud production of sulfate modifies aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in autumn 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4 (g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4 (g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.

  1. Detection response of elemental species in single particles using aerosol time-of-flight mass spectrometry

    SciTech Connect

    Silva, P.J.; Gross, D.S.; Gaelli, M.E.; Prather, K.A.

    1998-12-31

    The introduction of real-time particle mass spectrometry(RTSPMS) techniques creates a powerful tool for the study of particulate pollution on the single particle level. One such technique, aerosol time-of-flight mass spectrometry (ATOFMS) provides the aerodynamic size and chemical composition of individual particles. By combining data on size and composition, identification of individual particle classes in ambient outdoor samples is possible. Chemical composition is obtained by performing laser desorption ionization of individual particles using a Nd:YAG laser with a wavelength of 266 nm. The power of RTSPMS techniques is due to the ability to analyze the chemical composition of a single particle. The application of these techniques to analysis of ambient data has been limited however, because few studies have been performed to assess the ability of RTSPMS techniques to detect a wide range of compounds present in the atmosphere on a quantitative rather than qualitative level. It is known that various elemental species will respond differently to laser desorption mass spectrometric detection due to characteristic absorption cross-section and ionization potentials. In order to determine the capability and biases of RTSPMS techniques for detection of elemental species, a series of in-laboratory and ambient experiments has been performed using controlled conditions. Particles of known concentration have been produced from solution using an aerosol generator and analyzed using ATOFMS to determine responses of individual elements on a single particle level. In addition, side-by-side analyses with traditional sampling methods such as MOUDI impactors provide data to show how ATOFMS measurements correlate with federal reference methods.

  2. A new coincidence model for single particle counters, Part I: Theory and experimental verification.

    PubMed

    Knapp, J Z; Abramson, L R

    1994-01-01

    The prerequisites for estimating the effect of signal coincidence on both particle undercounting and the injection of false counts in the implementation of U.S.P. 788 contaminating particle assays by light extinction particle counters are defined. These include a particle concentration measure that varies with particle size and a new model of the counting process. Both prerequisites have been verified empirically: a single normalized equation describes the coincidence effect in all single particle counters. The single parameter of the normalized equation is the number of effective detector volumes per milliliter. A maximum undercount limit of 5% is proposed based on adequately suspended particles. Using the SVP U.S.P. XXII acceptance limits of 10,000 particles per container or the PMA propose 6,000 particles per container maximum for particles > 10 microns in U.S.P. XXIII, undercount errors are estimated for the smallest container sizes. The large concentration of particles below the controlled 10 microns particle size, that has been documented in injectable solutions, can pose an additional 788 measurement hazard. A Poisson model is used to estimate and control the injection of false particle counts into the mandated measurement through particle coincidence. Acceptable counting accuracy limits with present particle counting systems can be achieved by understanding the capabilities of the particle counter measurement system and using a dilution technique when appropriate. The new model of the counting process and the new particle concentration measures can result in standard, conservative, instrument specifications for use in Pharmacopeial contamination testing and in GLP user evaluation tests. Part I of this paper includes the theory of the coincidence effect on particle counting and the particle size distribution measured. A summary of the experimental verification employed to determine coincidence count loss as a function of particle concentration for single

  3. Spectroscopic properties of gold nanoparticles at the single-particle level in biological environments.

    PubMed

    Estrada, Laura C; Gratton, Enrico

    2012-03-01

    Labeling cells and tissues with fluorescent probes, such as organic dyes and quantum dots (Qdots) is a widespread and successful technique for studying molecular dynamics both in vitro and in vivo. However, those probes usually suffer from undesirable photophysical/photochemical processes, such as blinking and photobleaching, limiting their utilization. The main challenges in fluorescent probe design are to improve their absorption/emission properties, and to provide higher stability against photobleaching. In the last few years, metallic nanoparticles (NPs) of various sizes, shapes, and compositions have been used as a new alternative for cellular microscopy. This is in part because-unlike common organic dyes and Qdots-metallic NPs do not bleach or blink upon continuous illumination, are extremely stable, very bright, and their luminescence spans over the visible spectrum. These characteristics make them attractive contrast agents for cell imaging both in vitro and in vivo. For these reasons, the emission of metallic NPs in bulk solutions has already been extensively characterized. In contrast with bulk experiments, where billions of molecules are measured simultaneously, single-particle techniques allow the observation of characteristics and dynamical processes otherwise hidden in the measured average. A full understanding of the photophysical properties of the NPs is critical when they are used for single-molecule applications. Photophysical processes can be a source of artifacts if they are not interpreted accordingly, and thus a careful characterization of these labels at the single-particle level became crucial for the correct interpretation of the experimental results. Herein, we study some of their unique optical properties at the single-particle level and show examples that illustrate their intrinsic heterogeneity when used in biological environments. PMID:22298327

  4. Search for d3/2 single particle strength in 15N in Unbound Levels

    NASA Astrophysics Data System (ADS)

    Mertin, C. E.; Caussyn, D. D.; Crisp, A. M.; Keeley, N.; Kemper, K. W.; Momotyuk, O.; Roeder, B. T.; Volya, A.

    2013-10-01

    The population of states in the nucleus 15N provides the opportunity to investigate both single particle and cluster structures in the 1p and 2s1d shells. Single, two, three and four particle transfer reactions selectively excite states in 15N thus providing a way to explore current nuclear structure models. Narrow structures are observed in the various transfer reactions up to at least 20 MeV in excitation well above the neutron (10.8 MeV) and proton (10.2 MeV) separation energies. In the present work new results for the reaction 14N(d,p) are presented that explore possible single particle strengths up to 18 MeV in excitation. The beam energies used in the present work were between 10.5 and 16 MeV. An early work with a beam energy of 8 MeV clearly populated strong sharp levels at 10.07 and 11.23 MeV and the present work confirms their existence. In addition, very weak broader levels are populated at 12.13 and 12.5 MeV but no other structures are found experimentally at higher excitation energies. The results of shell model calculations that include the 1p and 2s1d shells will be presented. The centroid energies for the 1d5/2 and 2s1/2 single particle strength have been obtained through comparison with FRESCO calculations. This work was supported by the NSF, DOE and Florida State University.

  5. SPRING - an image processing package for single-particle based helical reconstruction from electron cryomicrographs.

    PubMed

    Desfosses, Ambroise; Ciuffa, Rodolfo; Gutsche, Irina; Sachse, Carsten

    2014-01-01

    Helical reconstruction from electron cryomicrographs has become a routine technique for macromolecular structure determination of helical assemblies since the first days of Fourier-based three-dimensional image reconstruction. In the past decade, the single-particle technique has had an important impact on the advancement of helical reconstruction. Here, we present the software package SPRING that combines Fourier based symmetry analysis and real-space helical processing into a single workflow. One of the most time-consuming steps in helical reconstruction is the determination of the initial symmetry parameters. First, we propose a class-based helical reconstruction approach that enables the simultaneous exploration and evaluation of many symmetry combinations at low resolution. Second, multiple symmetry solutions can be further assessed and refined by single-particle based helical reconstruction using the correlation of simulated and experimental power spectra. Finally, the 3D structure can be determined to high resolution. In order to validate the procedure, we use the reference specimen Tobacco Mosaic Virus (TMV). After refinement of the helical symmetry, a total of 50,000 asymmetric units from two micrographs are sufficient to reconstruct a subnanometer 3D structure of TMV at 6.4Å resolution. Furthermore, we introduce the individual programs of the software and discuss enhancements of the helical reconstruction workflow. Thanks to its user-friendly interface and documentation, SPRING can be utilized by the novice as well as the expert user. In addition to the study of well-ordered helical structures, the development of a streamlined workflow for single-particle based helical reconstruction opens new possibilities to analyze specimens that are heterogeneous in symmetries. PMID:24269218

  6. Troika of single particle tracking programing: SNR enhancement, particle identification, and mapping

    PubMed Central

    Shuang, Bo; Chen, Jixin; Kisley, Lydia

    2014-01-01

    single particle tracking (SPT) techniques provide a microscopic approach to probe in vivo and in vitro structure and reactions. Automatic analysis of SPT data with high efficiency and accuracy spurs the development of SPT algorithms. In this perspective, we review a range of available techniques used in SPT analysis programs. In addition, we present an example SPT program step-by-step to provide a guide so that researchers can use, modify, and/or write a SPT program for their own purposes. PMID:24263676

  7. First measurement of single-particle energies in {sup 100}Sn.

    SciTech Connect

    Seweryniak, D.

    2009-01-01

    Stable doubly magic nuclei have been the cornerstones of nuclear structure since the inception of the nuclear shell model. Doubly magic nuclei located far from the line of stability serve as a guide in the pursuit to understand ever more exotic systems. Single-particle energies and nucleon-nucleon interactions in doubly magic nuclei are stringent tests of nuclear models and are critical for understanding neighboring nuclei. They will play an essential role in developing universal interactions in nuclei that will consistently describe all nuclei.

  8. d/sub 5/2/-single particle strength in /sup 48/Ca + n

    SciTech Connect

    Harvey, J.A.; Johnson, C.H.; Carlton, R.F.; Castel, B.

    1984-01-01

    The neutron total cross section of /sup 48/Ca was measured up to 4 MeV and the data analyzed using an R-matrix code to obtain resonance parameters and potential scattering phase shifts. No s-wave resonances were observed and the small cross sections (approx. 0.5 b) at low energy requires a real well depth of 48 MeV. Three strong d-wave resonances (amounting to 45% of the single particle limit) were found in the 0.8 to 2.0 MeV energy region. Shell-model-in-the-continuum calculations agree with these observations.

  9. d/sub 5/2/-single particle strength in /sup 48/Ca+n

    SciTech Connect

    Harvey, J.A.; Johnson, C.H.; Carlton, R.F.; Castel, B.

    1985-01-20

    The neutron total cross section of /sup 48/Ca was measured up to 4 MeV and the data analyzed using an R-matrix code to obtain resonance parameters and potential scattering phase shifts. No s-wave resonances were observed and the small cross section (approx.0.5 b) at low energy requires a real well depth of 48 MeV. Three strong d-wave resonances (amounting to 45% of the single particle limit) were found in the 0.8 to 2.0 MeV energy region. Shell-model-in-the-continuum calculations agree with these observations.

  10. Adaptive optics enables three-dimensional single particle tracking at the sub-millisecond scale

    NASA Astrophysics Data System (ADS)

    Juette, Manuel F.; Rivera-Molina, Felix E.; Toomre, Derek K.; Bewersdorf, Joerg

    2013-04-01

    We present the integration of an adaptive optics element into a feedback-driven single particle tracking microscope. Our instrument captures three-dimensional (3D) trajectories with down to 130 μs temporal resolution for dynamic studies on the nanoscale. Our 3D beam steering approach tracks particles over an axial range of >6 μm with ˜2 ms mechanical response times and isolates the sample from any tracking motion. Tracking of transport vesicles containing Alexa488-labeled transferrin glycoprotein in living cells demonstrates the speed and sensitivity of our instrument.

  11. Collective and Single-Particle Motion in Beyond Mean Field Approaches.

    PubMed

    Egido, J Luis; Borrajo, Marta; Rodríguez, Tomás R

    2016-02-01

    We present a novel nuclear energy density functional method to calculate spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole deformations and rotational frequencies are considered simultaneously as the degrees of freedom within a symmetry conserving configuration mixing framework. The present method allows the study of nuclear states with collective and single-particle character. We calculate the fascinating structure of the semimagic ^{44}S nucleus as a first application of the method, obtaining an excellent quantitative agreement both with the available experimental data and with state-of-the-art shell model calculations. PMID:26894706

  12. Microscopic-macroscopic method for studying single-particle level density of superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Bezbakh, A. N.; Shneidman, T. M.; Adamian, G. G.; Antonenko, N. V.

    2014-04-01

    The intrinsic level densities of superheavy nuclei in the a-decay chains of 296,298,300120 nuclei are calculated using the single-particle spectra obtained with the modified two-center shell model. The level density parameters are extracted and compared with their phenomenological values used in the calculations of the survival of excited heavy nuclei. The dependences of the level density parameters on the mass and charge numbers as well as on the ground-state shell corrections are studied.

  13. Troika of single particle tracking programing: SNR enhancement, particle identification, and mapping.

    PubMed

    Shuang, Bo; Chen, Jixin; Kisley, Lydia; Landes, Christy F

    2014-01-14

    Single particle tracking (SPT) techniques provide a microscopic approach to probe in vivo and in vitro structure and reactions. Automatic analysis of SPT data with high efficiency and accuracy spurs the development of SPT algorithms. In this perspective, we review a range of available techniques used in SPT analysis programs. In addition, we present an example SPT program step-by-step to provide a guide so that researchers can use, modify, and/or write a SPT program for their own purposes. PMID:24263676

  14. The free-electron laser - Maxwell's equations driven by single-particle currents

    NASA Technical Reports Server (NTRS)

    Colson, W. B.; Ride, S. K.

    1980-01-01

    It is shown that if single particle currents are coupled to Maxwell's equations, the resulting set of self-consistent nonlinear equations describes the evolution of the electron beam and the amplitude and phase of the free-electron-laser field. The formulation is based on the slowly varying amplitude and phase approximation, and the distinction between microscopic and macroscopic scales, which distinguishes the microscopic bunching from the macroscopic pulse propagation. The capabilities of this new theoretical approach become apparent when its predictions for the ultrashort pulse free-electron laser are compared to experimental data; the optical pulse evolution, determined simply and accurately, agrees well with observations.

  15. Analytical Derivations of Single-Particle Matrix Elements in Nuclear Shell Model

    NASA Astrophysics Data System (ADS)

    Fatah, Aziz H.; Radhi, R. A.; Abdullah, Nzar R.

    2016-07-01

    We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)dr m where f(r) = rμ, rμ jJ(qr), V(r) corresponding to the Gaussian and the Yukawa potentials used in nuclear shell models and nuclear structure. In addition, we take into account a general integral formula of the matrix element that covers all seven matrix elements obtained analytically.

  16. Doing Foucault: inquiring into nursing knowledge with Foucauldian discourse analysis.

    PubMed

    Springer, Rusla Anne; Clinton, Michael E

    2015-04-01

    Foucauldian discourse analysis (FDA) is a methodology that is well suited to inquiring into nursing knowledge and its organization. It is a critical analytic approach derived from Foucault's histories of science, madness, medicine, incarceration and sexuality, all of which serve to exteriorize or make visible the 'positive unconscious of knowledge' penetrating bodies and minds. Foucauldian discourse analysis (FDA) holds the potential to reveal who we are today as nurses and as a profession of nursing by facilitating our ability to identify and trace the effects of the discourses that determine the conditions of possibility for nursing practice that are continuously shaping and (re)shaping the knowledge of nursing and the profession of nursing as we know it. In making visible the chain of knowledge that orders the spaces nurses occupy, no less than their subjectivities, FDA is a powerful methodology for inquiring into nursing knowledge based on its provocation of deep critical reflection on the normalizing power of discourse. PMID:25683171

  17. [Madness in Foucault: art and madness, madness and unreason].

    PubMed

    Providello, Guilherme Gonzaga Duarte; Yasui, Silvio

    2013-10-01

    After presenting the ideas on madness and its interface with art as expressed in the writings of Michel Foucault, Peter Pál Pelbart, and Gilles Deleuze, the article explores how these authors question the relationship between art and madness. It begins with the notion that madness does not tell the truth about art, and vice versa, but that there are links between both that must be delved into if we are to engage in deeper reflection on the topic. The text problematizes the statement that madness is the absence of an oeuvre and examines how this impacts the possibility of achieving an artistic oeuvre. It further problematizes the idea of madness as excluded language, that is, the idea that madness implies not only the exclusion of the body but also the disqualification of discourse. PMID:24473649

  18. Microfabricated high-bandpass foucault aperture for electron microscopy

    SciTech Connect

    Glaeser, Robert; Cambie, Rossana; Jin, Jian

    2014-08-26

    A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

  19. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  20. Single-particle structure determination by correlations of snapshot X-ray diffraction patterns (CXIDB ID 20)

    DOE Data Explorer

    Starodub, D.

    2013-03-25

    This deposition includes the diffraction images generated by the paired polystyrene spheres in random orientations. These images were used to determine and phase the single particle diffraction volume from their autocorrelation functions.

  1. Structural defect induced peak splitting in gold-copper bimetallic nanorods during growth by single particle spectroscopy.

    PubMed

    Thota, Sravan; Chen, Shutang; Zhou, Yadong; Zhang, Yong; Zou, Shengli; Zhao, Jing

    2015-09-21

    A single particle level study of bimetallic nanoparticle growth provides valuable information that is usually hidden in ensemble measurements, helping to improve the understanding of a reaction mechanism and overcome the synthetic challenges. In this study, we use single particle spectroscopy to monitor the changes in the scattering spectra of Au-Cu alloy nanorods during growth. We found that the unique features of the single particle scattering spectra were due to atomic level geometric defects in the nanorods. Electrodynamics simulations have demonstrated that small structural defects of a few atomic layers split the scattering peaks, giving rise to higher order modes, which do not exist in defect-free rods of similar geometry. The study shows that single particle scattering technique is as sensitive as high-resolution electron microscopy in revealing atomic level structural defects. PMID:26268683

  2. Interrogating discourse: the application of Foucault's methodological discussion to specific inquiry.

    PubMed

    Fadyl, Joanna K; Nicholls, David A; McPherson, Kathryn M

    2013-09-01

    Discourse analysis following the work of Michel Foucault has become a valuable methodology in the critical analysis of a broad range of topics relating to health. However, it can be a daunting task, in that there seems to be both a huge number of possible approaches to carrying out this type of project, and an abundance of different, often conflicting, opinions about what counts as 'Foucauldian'. This article takes the position that methodological design should be informed by ongoing discussion and applied as appropriate to a particular area of inquiry. The discussion given offers an interpretation and application of Foucault's methodological principles, integrating a reading of Foucault with applications of his work by other authors, showing how this is then applied to interrogate the practice of vocational rehabilitation. It is intended as a contribution to methodological discussion in this area, offering an interpretation of various methodological elements described by Foucault, alongside specific application of these aspects. PMID:23117590

  3. Structural defect induced peak splitting in gold-copper bimetallic nanorods during growth by single particle spectroscopy

    NASA Astrophysics Data System (ADS)

    Thota, Sravan; Chen, Shutang; Zhou, Yadong; Zhang, Yong; Zou, Shengli; Zhao, Jing

    2015-08-01

    A single particle level study of bimetallic nanoparticle growth provides valuable information that is usually hidden in ensemble measurements, helping to improve the understanding of a reaction mechanism and overcome the synthetic challenges. In this study, we use single particle spectroscopy to monitor the changes in the scattering spectra of Au-Cu alloy nanorods during growth. We found that the unique features of the single particle scattering spectra were due to atomic level geometric defects in the nanorods. Electrodynamics simulations have demonstrated that small structural defects of a few atomic layers split the scattering peaks, giving rise to higher order modes, which do not exist in defect-free rods of similar geometry. The study shows that single particle scattering technique is as sensitive as high-resolution electron microscopy in revealing atomic level structural defects.A single particle level study of bimetallic nanoparticle growth provides valuable information that is usually hidden in ensemble measurements, helping to improve the understanding of a reaction mechanism and overcome the synthetic challenges. In this study, we use single particle spectroscopy to monitor the changes in the scattering spectra of Au-Cu alloy nanorods during growth. We found that the unique features of the single particle scattering spectra were due to atomic level geometric defects in the nanorods. Electrodynamics simulations have demonstrated that small structural defects of a few atomic layers split the scattering peaks, giving rise to higher order modes, which do not exist in defect-free rods of similar geometry. The study shows that single particle scattering technique is as sensitive as high-resolution electron microscopy in revealing atomic level structural defects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03979g

  4. Revealing nonergodic dynamics in living cells from a single particle trajectory

    NASA Astrophysics Data System (ADS)

    Lanoiselée, Yann; Grebenkov, Denis S.

    2016-05-01

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

  5. Single particle tracking in systems showing anomalous diffusion: the role of weak ergodicity breaking.

    PubMed

    Burov, Stas; Jeon, Jae-Hyung; Metzler, Ralf; Barkai, Eli

    2011-02-01

    Anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells. The resulting time series are usually evaluated in terms of time averages. Often anomalous diffusion is connected with non-ergodic behaviour. In such cases the time averages remain random variables and hence irreproducible. Here we present a detailed analysis of the time averaged mean squared displacement for systems governed by anomalous diffusion, considering both unconfined and restricted (corralled) motion. We discuss the behaviour of the time averaged mean squared displacement for two prominent stochastic processes, namely, continuous time random walks and fractional Brownian motion. We also study the distribution of the time averaged mean squared displacement around its ensemble mean, and show that this distribution preserves typical process characteristics even for short time series. Recently, velocity correlation functions were suggested to distinguish between these processes. We here present analytical expressions for the velocity correlation functions. The knowledge of the results presented here is expected to be relevant for the correct interpretation of single particle trajectory data in complex systems. PMID:21203639

  6. Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

    SciTech Connect

    Zhu, Feng; Men, Long; Guo, Yijun; Zhu, Qiaochu; Bhattacharjee, Ujjal; Goodwin, Peter M.; Petrich, Jacob W.; Smith, Emily A.; Vela, Javier

    2015-02-09

    Organometallic halide perovskites CH3NH3PbX3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In our manuscript, we systematically synthesize CH3NH3PbX3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH3NH3PbX3 nanowires and nanorods capped with octylammonium halides show relatively higher photoluminescence (PL) quantum yields and long PL lifetimes. CH3NH3PbI3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. Our work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.

  7. Low cost, high performance processing of single particle cryo-electron microscopy data in the cloud.

    PubMed

    Cianfrocco, Michael A; Leschziner, Andres E

    2015-01-01

    The advent of a new generation of electron microscopes and direct electron detectors has realized the potential of single particle cryo-electron microscopy (cryo-EM) as a technique to generate high-resolution structures. Calculating these structures requires high performance computing clusters, a resource that may be limiting to many likely cryo-EM users. To address this limitation and facilitate the spread of cryo-EM, we developed a publicly available 'off-the-shelf' computing environment on Amazon's elastic cloud computing infrastructure. This environment provides users with single particle cryo-EM software packages and the ability to create computing clusters with 16-480+ CPUs. We tested our computing environment using a publicly available 80S yeast ribosome dataset and estimate that laboratories could determine high-resolution cryo-EM structures for $50 to $1500 per structure within a timeframe comparable to local clusters. Our analysis shows that Amazon's cloud computing environment may offer a viable computing environment for cryo-EM. PMID:25955969

  8. Combustion particles as ice nuclei in an urban environment: Evidence from single-particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Corbin, J. C.; Rehbein, P. J. G.; Evans, G. J.; Abbatt, J. P. D.

    2012-05-01

    This paper presents measurements of the single-particle composition of ice nuclei (IN) in downtown Toronto, Canada, made at 239 ± 1 K, 134 ± 2% relative humidity with respect to ice (RHi). IN were activated within the University of Toronto Continuous-Flow Diffusion Chamber (UT-CFDC), separated from background aerosol using a pumped counterflow virtual impactor (PCVI), and analyzed using a dual-polarity single-particle mass spectrometer (ATOFMS). To account for particles leaked by the PCVI, the ratio of particles observed at high RHi to low RHi was calculated. This ratio was greater than unity for EC (elemental carbon), BB (biomass burning) and dust particles, however only the increase in EC was statistically significant (1σ level) due to a low number of detected particles. The remaining particle categories were: metal-rich organic carbon (M/OC), potassium-rich OC (K/OC), OC potentially mixed with EC (OC/EC) and “other”, none of which were enhanced in number at high RHi. To complement the direct PCVI observations and enhance the number of spectra available, a second study was performed where particle composition and IN concentrations (CIN) were measured in parallel. IN concentrations were regressed against the same categories as above, and dust, BB and EC particles were identified as the best predictors of CIN. Consistency between these two methods provides increased confidence in their individual results and encourages additional study of these potential IN.

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

    NASA Astrophysics Data System (ADS)

    Kepten, Eldad; Bronshtein, Irena; Garini, Yuval

    2013-05-01

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

  10. Single Particle Cryo-electron Microscopy and 3-D Reconstruction of Viruses

    PubMed Central

    Guo, Fei; Jiang, Wen

    2014-01-01

    With fast progresses in instrumentation, image processing algorithms, and computational resources, single particle electron cryo-microscopy (cryo-EM) 3-D reconstruction of icosahedral viruses has now reached near-atomic resolutions (3–4 Å). With comparable resolutions and more predictable outcomes, cryo-EM is now considered a preferred method over X-ray crystallography for determination of atomic structure of icosahedral viruses. At near-atomic resolutions, all-atom models or backbone models can be reliably built that allow residue level understanding of viral assembly and conformational changes among different stages of viral life cycle. With the developments of asymmetric reconstruction, it is now possible to visualize the complete structure of a complex virus with not only its icosahedral shell but also its multiple non-icosahedral structural features. In this chapter, we will describe single particle cryo-EM experimental and computational procedures for both near-atomic resolution reconstruction of icosahedral viruses and asymmetric reconstruction of viruses with both icosahedral and non-icosahedral structure components. Procedures for rigorous validation of the reconstructions and resolution evaluations using truly independent de novo initial models and refinements are also introduced. PMID:24357374

  11. Anomalous temperature dependence of the single-particle spectrum in the organic conductor TTF-TCNQ

    NASA Astrophysics Data System (ADS)

    Bulut, Nejat; Matsueda, Hiroaki; Tohyama, Takami; Maekawa, Sadamichi

    2006-03-01

    The angle-resolved photoemission spectrum of the quasi-one-dimensional organic-conductor TTF-TCNQ exhibits an unusual temperature dependence in the sense that a transfer of spectral weight over an energy range of 1eV takes place as the temperature decreases below 260K. In order to investigate the origin of this behavior, we have performed Dynamical Density-Matrix-Renomalization-Group (DDMRG) calculations at zero temperature and Quantum Monte Carlo (QMC) calculations at finite temperatures for the single-particle spectral weight of the doped one-dimensional (1D) Hubbard model. We present DDMRG and QMC results for a range of the model parameters of the 1D Hubbard model and make comparisons with the photoemission data. In addition, we present zero-temperature DDMRG results on the doped 1D Hubbard-Holstein model in order to explore how the electron-phonon coupling influences the single-particle spectrum in 1D correlated conductors.

  12. Two-particle and single-particle spin-dependent interactions in topological insulators

    NASA Astrophysics Data System (ADS)

    Radu, Marius; Lyanda-Geller, Yuli

    2014-03-01

    We derive single-particle and two-particle interaction Hamiltonians describing physics of two-dimensional topological insulators based on HgTe-CdTe quantum well structures by using k . p theory and extended Kane model. We include contributions from upper conduction band with orbital states of p-symmetry that bring about the terms describing lack of inversion symmetry in host semiconductors. Single-particle Hamiltonian and two-particle Hamiltonian contain important spin-dependent diagonal and off-diagonal terms. We demonstrate how these terms affect spin currents, interference effects in conductance such as weak localization and anti-localization, and contribute to spin relaxation and dephasing. The spin-dependent interaction terms couple orbital motion of one particle with evolution of spin of the other particle. Such particle-particle interactions do not conserve spin and lower the symmetry of exchange interactions, leading, e.g., to Dzyaloshinskii-Moriya exchange term. Support of Purdue Center for Topological Materials is gratefully acknowledged.

  13. Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

    DOE PAGESBeta

    Zhu, Feng; Men, Long; Guo, Yijun; Zhu, Qiaochu; Bhattacharjee, Ujjal; Goodwin, Peter M.; Petrich, Jacob W.; Smith, Emily A.; Vela, Javier

    2015-02-09

    Organometallic halide perovskites CH3NH3PbX3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In our manuscript, we systematically synthesize CH3NH3PbX3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH3NH3PbX3 nanowires and nanorods capped with octylammonium halides show relatively highermore » photoluminescence (PL) quantum yields and long PL lifetimes. CH3NH3PbI3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. Our work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.« less

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  15. Single-particle spectral function for the classical one-component plasma

    NASA Astrophysics Data System (ADS)

    Fortmann, C.

    2009-01-01

    The spectral function for an electron one-component plasma is calculated self-consistently using the GW(0) approximation for the single-particle self-energy. In this way, correlation effects that go beyond the mean-field description of the plasma are contained, i.e., the collisional damping of single-particle states, the dynamical screening of the interaction, and the appearance of collective plasma modes. Second, a nonperturbative analytic solution for the on-shell GW(0) self-energy as a function of momentum is presented. It reproduces the numerical data for the spectral function with a relative error of less than 10% in the regime where the Debye screening parameter is smaller than the inverse Bohr radius, κ<1aB-1 . In the limit of low density, the nonperturbative self-energy behaves as n1/4 , whereas a perturbation expansion leads to the unphysical result of a density-independent self-energy [Fennel and Wilfer, Ann. Phys. (Leipzig) 32, 265 (1974)]. The derived expression will greatly facilitate the calculation of observables in correlated plasmas (transport properties, equation of state) that need the spectral function as an input quantity. This is demonstrated for the shift of the chemical potential, which is computed from the analytical formulas and compared to the GW(0) result. At a plasma temperature of 100eV and densities below 1021cm-3 , the two approaches deviate by less than 10% from each other.

  16. Bidirectional reflectance spectroscopy 7. The single particle phase function hockey stick relation

    NASA Astrophysics Data System (ADS)

    Hapke, Bruce

    2012-11-01

    The measured volume-average single particle angular scattering functions of a large number of types of particle of interest for planetary regoliths in the visible-near-IR wavelength region can be represented to a reasonable approximation by two-parameter, double Henyey-Greenstein functions. When the two parameters of this function are plotted against one another they are found to be inversely correlated and lie within a restricted zone shaped like a hockey stick within the parameter space. The centroid of the zone is a curve that can be represented by a simple empirical equation. The wide variety of types of particles used to construct the plot implies that this equation may represent most of the particles found in regoliths. This means that when modeling the bidirectional reflectance of a regolith it may be possible to reduce the number of parameters necessary to specify the reflectance, and also to characterize the entire single particle phase function from observations at phase angles less than 90°. Even if the hockey stick relation has a finite width, rather than being a line, it restricts the parameter space that must be searched when fitting data. The curve should also be useful for forward modeling particle phase functions.

  17. Beyond single particle mass spectrometry: multidimensional characterisation of individual aerosol particles

    SciTech Connect

    Zelenyuk, Alla; Imre, D.

    2009-09-10

    The behavior of small aerosol particles depends on a number of their physical and chemical properties, many of which are strongly coupled. The size, internal composition, density, shape, morphology, hygroscopicity, index of refraction, activity as cloud condensation nuclei and ice nuclei, and other attributes of individual particles - all play a role in determining particle properties and their impacts. The traditional particle characterization approaches rely on separate parallel measurements that average over an ensemble of particles of different sizes and/or compositions and later attempt to draw correlations between them. As a result such studies overlook critical differences between particles and bulk and miss the fact that individual particles often exhibit major differences. Here we review the recently developed methods to simultaneously measure in-situ and in real time several of the attributes for individual particles using single particle mass spectrometer, SPLAT or its second generation SPLAT II. We also discuss novel approaches developed for classification, visualization and mining of large datasets produced by the multidimensional single particle characterization.

  18. Low cost, high performance processing of single particle cryo-electron microscopy data in the cloud

    PubMed Central

    Cianfrocco, Michael A; Leschziner, Andres E

    2015-01-01

    The advent of a new generation of electron microscopes and direct electron detectors has realized the potential of single particle cryo-electron microscopy (cryo-EM) as a technique to generate high-resolution structures. Calculating these structures requires high performance computing clusters, a resource that may be limiting to many likely cryo-EM users. To address this limitation and facilitate the spread of cryo-EM, we developed a publicly available ‘off-the-shelf’ computing environment on Amazon's elastic cloud computing infrastructure. This environment provides users with single particle cryo-EM software packages and the ability to create computing clusters with 16–480+ CPUs. We tested our computing environment using a publicly available 80S yeast ribosome dataset and estimate that laboratories could determine high-resolution cryo-EM structures for $50 to $1500 per structure within a timeframe comparable to local clusters. Our analysis shows that Amazon's cloud computing environment may offer a viable computing environment for cryo-EM. DOI: http://dx.doi.org/10.7554/eLife.06664.001 PMID:25955969

  19. Study of the comminution characteristics of coal by single particle breakage test device

    SciTech Connect

    Sahoo, R.

    2005-09-01

    Single-particle breakage tests of South Blackwater and Ensham coal from the Bowen Basin area in Queensland were conducted by a computer-monitored twin-pendulum device to measure the energy utilization pattern of the breakage particles. Three particle sizes (-16.0+13.2mm, -13.2+11.2mm, -11.2+9.5mm) of each coal were tested by a pendulum device at five input energy levels to measure the specific comminution energy. When particles were tested at constant input energy, the variation of comminution energy between the same size broken particles of Ensham coal was minimal, because Ensham coal is a softer and higher friability coal, which absorbs more input energy than harder coal during breakage tests. For different particle sizes, the specific comminution energy increases linearly with the input energy and the fineness of the breakage products increases with the specific comminution energy. The size distribution graphs are curved but approach linearity in the finer region. At a constant input energy, the twin pendulum breakage product results show that the fineness of the products increases with decrease in particle size and South Blackwater coal produced finer products than the Ensham coal. The t-curves are the family of size distribution curves, which can describe the product size distribution of the breakage particles during single-particle breakage tests.

  20. Maskiton: Interactive, Web-based Classification of Single-Particle Electron Microscopy Images

    PubMed Central

    Yoshioka, Craig; Lyumkis, Dmitry; Carragher, Bridget; Potter, Clinton S.

    2013-01-01

    Electron microscopy (EM) is an important tool for determining the composition, arrangement and structure of biological macromolecules. When studying structurally heterogeneous samples using EM, classification is a critical step toward achieving higher resolution and identifying biologically significant conformations. We have developed an interactive, web-based tool, called Maskiton, for creating custom masks and performing 2D classifications on aligned single-particle EM images. The Maskiton interface makes it considerably easier and faster to explore the significance of heterogeneity in single-particle datasets. Maskiton features include: resumable uploads to facilitate transfer of large datasets to the server, custom mask creation in the browser, continual progress updates, and interactive viewing of classification results. To demonstrate the value of this tool, we provide examples of its use on several experimental datasets and include analyses of the independent terminus mobility within the Ltn1 E3 ubiquitin ligase, the in-vitro assembly of 30S ribosomal subunits, and classification complexity reduction within Immunoglobulin M. This work also serves as a proof-of-concept for the development of future cross-platform, interactive user interfaces for electron microscopy data processing. PMID:23428431

  1. Single-Particle Composition Measured in an Alpine Valley: Wood Smoke, EC and BC

    NASA Astrophysics Data System (ADS)

    Liepmann, C.; Gross, D. S.; Benzaid, S.; Christensen, J.; Turetsky, E.; Musicant, D.; Sandradewi, J.; Prevot, A.; Baltensperger, U.

    2007-12-01

    Particulate pollution is an issue of concern in today's society. Current regulations focus on the mass of particulate matter (PM) per volume of air, and not the source or chemical composition of the PM. Here we will present results from the AEROWOOD campaign in Roveredo, Switzerland where we investigated the PM composition measured using a single-particle mass spectrometer (TSI 3800 ATOFMS) to identify the sources of ambient particles. The goal was to differentiate wood smoke particles from diesel emissions. Roveredo is located in a deep alpine valley with strong wintertime thermal inversions, trapping the emissions. Local homes are predominantly heated by wood fires, and the village is located along a motorway that crosses the Swiss alps, providing two distinct particle sources. The particles sampled with the ATOFMS have been analyzed in a variety of ways with a focus on the temporal trends of the different particle types identified. Of particular interest is the distinction made between elemental carbon (EC) and black carbon (BC). During AEROWOOD, EC was measured chemically using real- time thermo/optical methods. BC was recorded directly by absorption, using an aethalometer. Regression models have been constructed to predict the EC and BC values using the single-particle mass spectra, providing chemical insight into the differences in these quantities. Additionally, comparing the timeline plots of EC, BC and the particle types found from the ATOFMS data should provide an idea as to the sources of EC and BC in this location.

  2. Particle migration analysis in iterative classification of cryo-EM single-particle data

    PubMed Central

    Chen, Bo; Shen, Bingxin; Frank, Joachim

    2014-01-01

    Recently developed classification methods have enabled resolving multiple biological structures from cryo-EM data collected on heterogeneous biological samples. However, there remains the problem of how to base the decisions in the classification on the statistics of the cryo-EM data, to reduce the subjectivity in the process. Here, we propose a quantitative analysis to determine the iteration of convergence and the number of distinguishable classes, based on the statistics of the single particles in an iterative classification scheme. We start the classification with more number of classes than anticipated based on prior knowledge, and then combine the classes that yield similar reconstructions. The classes yielding similar reconstructions can be identified from the migrating particles (jumpers) during consecutive iterations after the iteration of convergence. We therefore termed the method “jumper analysis”, and applied it to the output of RELION 3D classification of a benchmark experimental dataset. This work is a step forward toward fully automated single-particle reconstruction and classification of cryo-EM data. PMID:25449317

  3. Foucault and the 'Anti-Oedipus movement': psychoanalysis as disciplinary power.

    PubMed

    Basaure, Mauro

    2009-09-01

    What psychiatry was for the anti-psychiatry movement, psychoanalysis was for the French 'Anti-Oedipus movement' represented by Robert Castel, Gilles Deleuze and Felix Guattari. Until now, the contribution of Foucault to this critical movement has been little known. In this paper I reconstruct in a systematic and exhaustive way Foucault's critique of psychoanalysis and, in particular, of the Oedipus-complex theory. I demonstrate that this critique presupposes a very specific epistemology and social theory. On an epistemological level, Foucault focuses on the power effects of psychoanalysis as a discourse of subjectivity. On a social-theoretical level, Foucault assumes a functionalist conception of society. These two aspects of Foucault's critique of psychoanalysis have not been adequately recognized in the discussion about his relationship to psychoanalysis (Derrida, Miller, Whitebook, among others). I argue that a fruitful dialogue between a Foucault-inspired critical social theory and psychoanalysis can take place only if these two distinct aspects are taken into account. PMID:20030163

  4. [Analysis of Single Particle Aging and Mixing State at an Agriculture Site (Quzhou) in the North China Plain in Summer Using a Single Particle Aerosol Mass Spectrometer].

    PubMed

    Huang, Zi-long; Zeng, Li-mm; Dong, I-Iua-Bin; Li, Mei; Zhu, Tong

    2016-04-15

    To characterize the size distribution and chemical ompsitins f abiet prtices t a agicuturesit intheNorh o Chinese Plain, a single particle aerosol mass spectrometer (SPAMS) was deployed from June 30 to July 8, 2013. A total of 230,152 particles in the size range of 0.2-2.0 pm were chemically analyzed with both positive and negative ion spectra. The results revealed that aerosol could he classified into eight dominant groups, including elemental carbon (EC, 55.5%), organic carbon (OC, 10.7%), alkalis (Na-K, 17.4%), other metals (1.7%), Fe-rich (6.3%), Pb-rich (3.1%), dust (4.8%), and other (0.8%). The observed eight types of particles contained secondary components such as 46NO2-, 62NO3-, 96SO3-, 96SO4-, 97HSO4-, showing that they probably went through different aging processes. The analysis of particle size distribution showed that 700-800 nm was the peak value of all particles, and that dust and Fe particles were mainly in the coarse size range. EC particles subtype group research revealed EC particles tended to be aging with the above mentioned secondary ions and eventually led to a particle type conversion from EC to the less aging ECN and the more serious aging ECS, the diurnal variation of which was obviously negatively correlated, and there was a possibility of forming OC/EC mixture with the adsorption of secondary organic matter on EC surface. PMID:27548937

  5. Non-Perturbative Many-Body Approach to the Hubbard Model and Single-Particle Pseudogap

    NASA Astrophysics Data System (ADS)

    Vilk, Y. M.; Tremblay, A.-M. S.

    1997-11-01

    A new approach to the single-band Hubbard model is described in the general context of many-body theories. It is based on enforcing conservation laws, the Pauli principle and a number of crucial sum-rules. More specifically, spin and charge susceptibilities are expressed, in a conserving approximation, as a function of two irreducible vertices whose values are found by imposing the local Pauli principle <~ngle n^2_\\uparrowrangle = <~ngle n_\\uparrowrangle as well as the local-moment sum-rule and consistency with the equations of motion in a local-field approximation. The Mermin-Wagner theorem in two dimensions is automatically satisfied. The effect of collective modes on single-particle properties is then obtained by a paramagnon-like formula that is consistent with the two-particle properties in the sense that the potential energy obtained from Tr Σ G is identical to that obtained using the fluctuation-dissipation theorem for susceptibilities. Since there is no Migdal theorem controlling the effect of spin and charge fluctuations on the self-energy, the required vertex corrections are included. It is shown that the theory is in quantitative agreement with Monte Carlo simulations for both single-particle and two-particle properties. The theory predicts a magnetic phase diagram where magnetic order persists away from half-filling but where ferromagnetism is completely suppressed. Both quantum-critical and renormalized-classical behavior can occur in certain parameter ranges. It is shown that in the renormalized classical regime, spin fluctuations lead to precursors of antiferromagnetic bands (shadow bands) and to the destruction of the Fermi-liquid quasiparticles in a wide temperature range above the zero-temperature phase transition. The upper critical dimension for this phenomenon is three. The analogous phenomenon of pairing pseudogap can occur in the attractive model in two dimensions when the pairing fluctuations become critical. Simple analytical expressions

  6. Fast Three-Dimensional Single-Particle Tracking in Natural Brain Tissue.

    PubMed

    Sokoll, Stefan; Prokazov, Yury; Hanses, Magnus; Biermann, Barbara; Tönnies, Klaus; Heine, Martin

    2015-10-01

    Observation of molecular dynamics is often biased by the optical very heterogeneous environment of cells and complex tissue. Here, we have designed an algorithm that facilitates molecular dynamic analyses within brain slices. We adjust fast astigmatism-based three-dimensional single-particle tracking techniques to depth-dependent optical aberrations induced by the refractive index mismatch so that they are applicable to complex samples. In contrast to existing techniques, our online calibration method determines the aberration directly from the acquired two-dimensional image stream by exploiting the inherent particle movement and the redundancy introduced by the astigmatism. The method improves the positioning by reducing the systematic errors introduced by the aberrations, and allows correct derivation of the cellular morphology and molecular diffusion parameters in three dimensions independently of the imaging depth. No additional experimental effort for the user is required. Our method will be useful for many imaging configurations, which allow imaging in deep cellular structures. PMID:26445447

  7. Single-Particle Refinement and Variability Analysis in EMAN2.1.

    PubMed

    Ludtke, S J

    2016-01-01

    CryoEM single-particle reconstruction has been growing rapidly over the last 3 years largely due to the development of direct electron detectors, which have provided data with dramatic improvements in image quality. It is now possible in many cases to produce near-atomic resolution structures, and yet 2/3 of published structures remain at substantially lower resolutions. One important cause for this is compositional and conformational heterogeneity, which is both a resolution-limiting factor and presenting a unique opportunity to better relate structure to function. This manuscript discusses the canonical methods for high-resolution refinement in EMAN2.12, and then considers the wide range of available methods within this package for resolving structural variability, targeting both improved resolution and additional knowledge about particle dynamics. PMID:27572727

  8. Imaging of molecular surface dynamics in brain slices using single-particle tracking

    PubMed Central

    Biermann, B.; Sokoll, S.; Klueva, J.; Missler, M.; Wiegert, J. S.; Sibarita, J. -B.; Heine, M.

    2014-01-01

    Organization of signalling molecules in biological membranes is crucial for cellular communication. Many receptors, ion channels and cell adhesion molecules are associated with proteins important for their trafficking, surface localization or function. These complexes are embedded in a lipid environment of varying composition. Binding affinities and stoichiometry of such complexes were so far experimentally accessible only in isolated systems or monolayers of cell culture. Visualization of molecular dynamics within signalling complexes and their correlation to specialized membrane compartments demand high temporal and spatial resolution and has been difficult to demonstrate in complex tissue like brain slices. Here we demonstrate the feasibility of single-particle tracking (SPT) in organotypic brain slices to measure molecular dynamics of lipids and transmembrane proteins in correlation to synaptic membrane compartments. This method will provide important information about the dynamics and organization of surface molecules in the complex environment of neuronal networks within brain slices. PMID:24429796

  9. Fabrication of bright and small size semiconducting polymer nanoparticles for cellular labelling and single particle tracking.

    PubMed

    Wei, Lin; Zhou, Peng; Yang, Qingxiu; Yang, Qiaoyu; Ma, Ming; Chen, Bo; Xiao, Lehui

    2014-10-01

    In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 ± 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance. PMID:25141182

  10. An efficient, movable single-particle detector for use in cryogenic ultra-high vacuum environments

    SciTech Connect

    Spruck, Kaija; Becker, Arno; Fellenberger, Florian; Grieser, Manfred; Hahn, Robert von; Klinkhamer, Vincent; Vogel, Stephen; Wolf, Andreas; Krantz, Claude; Novotný, Oldřich; Schippers, Stefan

    2015-02-15

    A compact, highly efficient single-particle counting detector for ions of keV/u kinetic energy, movable by a long-stroke mechanical translation stage, has been developed at the Max-Planck-Institut für Kernphysik (Max Planck Institute for Nuclear Physics, MPIK). Both, detector and translation mechanics, can operate at ambient temperatures down to ∼10 K and consist fully of ultra-high vacuum compatible, high-temperature bakeable, and non-magnetic materials. The set-up is designed to meet the technical demands of MPIK’s Cryogenic Storage Ring. We present a series of functional tests that demonstrate full suitability for this application and characterise the set-up with regard to its particle detection efficiency.

  11. Mechanistic understanding of surface plasmon assisted catalysis on a single particle: cyclic redox of 4-aminothiophenol

    DOE PAGESBeta

    Xu, Ping; Kang, Leilei; Mack, Nathan H.; Schanze, Kirk S.; Han, Xijiang; Wang, Hsing-Lin

    2013-10-21

    We investigate surface plasmon assisted catalysis (SPAC) reactions of 4-aminothiophenol (4ATP) to and back from 4,4'-dimercaptoazobenzene (DMAB) by single particle surface enhanced Raman spectroscopy, using a self-designed gas flow cell to control the reductive/oxidative environment over the reactions. Conversion of 4ATP into DMAB is induced by energy transfer (plasmonic heating) from surface plasmon resonance to 4ATP, where O2 (as an electron acceptor) is essential and H2O (as a base) can accelerate the reaction. In contrast, hot electron (from surface plasmon decay) induction drives the reverse reaction of DMAB to 4ATP, where H2O (or H2) acts as the hydrogen source. Moremore » interestingly, the cyclic redox between 4ATP and DMAB by SPAC approach has been demonstrated. Finally, this SPAC methodology presents a unique platform for studying chemical reactions that are not possible under standard synthetic conditions.« less

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  13. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins

    NASA Astrophysics Data System (ADS)

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; van Dyck, Dirk; Chen, Fu-Rong

    2016-06-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images.

  14. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins.

    PubMed

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; Van Dyck, Dirk; Chen, Fu-Rong

    2016-01-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images. PMID:27292544

  15. Neutron Single Particle Strengths from the (d,p) Reaction on 18F

    SciTech Connect

    Kozub, R. L.; Bardayan, Daniel W; Batchelder, Jon Charles; Blackmon, Jeff C; Brune, Carl; Champagne, A. E.; Cizewski, J. A.; Greife, U.; Gross, Carl J; Jewett, Cybele; Livesay, Jake; Ma, Zhanwen; Moazen, Brian; Nesaraja, Caroline D; Sahin, L.; Shapira, Dan; Smith, Michael Scott; Thomas, J. S.

    2006-01-01

    The 19F nucleus has been studied extensively. However, there have been no comprehensive experimental studies of 18F+n single-particle components in 19F, and no measure of neutron vacancies in the 18F ground state, as such experiments require a (radioactive) 18F target or beam. We have used the 2H(18F,p)19F reaction to selectively populate states in 19F that are of 18F+n character. The 108.5-MeV radioactive 18F+9 beam was provided by the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Proton-recoil coincidence data were taken for both -decaying and particle-stable final states. Angular distributions and spectroscopic factors were measured for nine proton groups, corresponding to 13 states in 19F. The results are compared to shell model calculations.

  16. Dragonfly: an implementation of the expand–maximize–compress algorithm for single-particle imaging1

    PubMed Central

    Ayyer, Kartik; Lan, Ti-Yen; Elser, Veit; Loh, N. Duane

    2016-01-01

    Single-particle imaging (SPI) with X-ray free-electron lasers has the potential to change fundamentally how biomacromolecules are imaged. The structure would be derived from millions of diffraction patterns, each from a different copy of the macromolecule before it is torn apart by radiation damage. The challenges posed by the resultant data stream are staggering: millions of incomplete, noisy and un-oriented patterns have to be computationally assembled into a three-dimensional intensity map and then phase reconstructed. In this paper, the Dragonfly software package is described, based on a parallel implementation of the expand–maximize–compress reconstruction algorithm that is well suited for this task. Auxiliary modules to simulate SPI data streams are also included to assess the feasibility of proposed SPI experiments at the Linac Coherent Light Source, Stanford, California, USA. PMID:27504078

  17. Chaos and nonlinear dynamics of single-particle orbits in a magnetotaillike magnetic field

    NASA Technical Reports Server (NTRS)

    Chen, J.; Palmadesso, P. J.

    1986-01-01

    The properties of charged-particle motion in Hamiltonian dynamics are studied in a magnetotaillike magnetic field configuration. It is shown by numerical integration of the equation of motion that the system is generally nonintegrable and that the particle motion can be classified into three distinct types of orbits: bounded integrable orbits, unbounded stochastic orbits, and unbounded transient orbits. It is also shown that different regions of the phase space exhibit qualitatively different responses to external influences. The concept of 'differential memory' in single-particle distributions is proposed. Physical implications for the dynamical properties of the magnetotail plasmas and the possible generation of non-Maxwellian features in the distribution functions are discussed.

  18. Estimating the anomalous diffusion exponent for single particle tracking data with measurement errors - An alternative approach

    NASA Astrophysics Data System (ADS)

    Burnecki, Krzysztof; Kepten, Eldad; Garini, Yuval; Sikora, Grzegorz; Weron, Aleksander

    2015-06-01

    Accurately characterizing the anomalous diffusion of a tracer particle has become a central issue in biophysics. However, measurement errors raise difficulty in the characterization of single trajectories, which is usually performed through the time-averaged mean square displacement (TAMSD). In this paper, we study a fractionally integrated moving average (FIMA) process as an appropriate model for anomalous diffusion data with measurement errors. We compare FIMA and traditional TAMSD estimators for the anomalous diffusion exponent. The ability of the FIMA framework to characterize dynamics in a wide range of anomalous exponents and noise levels through the simulation of a toy model (fractional Brownian motion disturbed by Gaussian white noise) is discussed. Comparison to the TAMSD technique, shows that FIMA estimation is superior in many scenarios. This is expected to enable new measurement regimes for single particle tracking (SPT) experiments even in the presence of high measurement errors.

  19. Anomalous temperature dependence of the single-particle spectrum in the organic conductor TTF-TCNQ

    NASA Astrophysics Data System (ADS)

    Bulut, N.; Matsueda, H.; Tohyama, T.; Maekawa, S.

    2006-09-01

    The angle-resolved photoemission spectrum of the organic conductor TTF-TCNQ exhibits an unusual transfer of spectral weight over a wide energy range for temperatures 60Ksingle-particle spectral weight A(k,ω) for the one-dimensional (1D) Hubbard model and, in addition, for the 1D extended Hubbard and the 1D Hubbard-Holstein models. Comparisons with the photoemission data suggest that the 1D Hubbard model is not sufficient for explaining the unusual T dependence, and the long-range part of the Coulomb repulsion also needs to be included.

  20. Estimating the anomalous diffusion exponent for single particle tracking data with measurement errors - An alternative approach

    PubMed Central

    Burnecki, Krzysztof; Kepten, Eldad; Garini, Yuval; Sikora, Grzegorz; Weron, Aleksander

    2015-01-01

    Accurately characterizing the anomalous diffusion of a tracer particle has become a central issue in biophysics. However, measurement errors raise difficulty in the characterization of single trajectories, which is usually performed through the time-averaged mean square displacement (TAMSD). In this paper, we study a fractionally integrated moving average (FIMA) process as an appropriate model for anomalous diffusion data with measurement errors. We compare FIMA and traditional TAMSD estimators for the anomalous diffusion exponent. The ability of the FIMA framework to characterize dynamics in a wide range of anomalous exponents and noise levels through the simulation of a toy model (fractional Brownian motion disturbed by Gaussian white noise) is discussed. Comparison to the TAMSD technique, shows that FIMA estimation is superior in many scenarios. This is expected to enable new measurement regimes for single particle tracking (SPT) experiments even in the presence of high measurement errors. PMID:26065707

  1. Single-particle structure determination by correlations of snapshot X-ray diffraction patterns.

    PubMed

    Starodub, D; Aquila, A; Bajt, S; Barthelmess, M; Barty, A; Bostedt, C; Bozek, J D; Coppola, N; Doak, R B; Epp, S W; Erk, B; Foucar, L; Gumprecht, L; Hampton, C Y; Hartmann, A; Hartmann, R; Holl, P; Kassemeyer, S; Kimmel, N; Laksmono, H; Liang, M; Loh, N D; Lomb, L; Martin, A V; Nass, K; Reich, C; Rolles, D; Rudek, B; Rudenko, A; Schulz, J; Shoeman, R L; Sierra, R G; Soltau, H; Steinbrener, J; Stellato, F; Stern, S; Weidenspointner, G; Frank, M; Ullrich, J; Strüder, L; Schlichting, I; Chapman, H N; Spence, J C H; Bogan, M J

    2012-01-01

    Diffractive imaging with free-electron lasers allows structure determination from ensembles of weakly scattering identical nanoparticles. The ultra-short, ultra-bright X-ray pulses provide snapshots of the randomly oriented particles frozen in time, and terminate before the onset of structural damage. As signal strength diminishes for small particles, the synthesis of a three-dimensional diffraction volume requires simultaneous involvement of all data. Here we report the first application of a three-dimensional spatial frequency correlation analysis to carry out this synthesis from noisy single-particle femtosecond X-ray diffraction patterns of nearly identical samples in random and unknown orientations, collected at the Linac Coherent Light Source. Our demonstration uses unsupported test particles created via aerosol self-assembly, and composed of two polystyrene spheres of equal diameter. The correlation analysis avoids the need for orientation determination entirely. This method may be applied to the structural determination of biological macromolecules in solution. PMID:23232406

  2. Single-particle light scattering study of polyethyleneglycol-grafted poly(ureaurethane) microcapsule in ethanol.

    PubMed

    Terao, Ken; Ohsawa, Akane; Mori, Yasutaka; Narita, Takayuki; Ichikawa, Kimio; Dobashi, Toshiaki

    2004-09-01

    Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol. PMID:15342022

  3. Applications of differential algebra to single-particle dynamics in storage rings

    SciTech Connect

    Yan, Y.

    1991-09-01

    Recent developments in the use of differential algebra to study single-particle beam dynamics in charged-particle storage rings are the subject of this paper. Chapter 2 gives a brief review of storage rings. The concepts of betatron motion and synchrotron motion, and their associated resonances, are introduced. Also introduced are the concepts of imperfections, such as off-momentum, misalignment, and random and systematic errors, and their associated corrections. The chapter concludes with a discussion of numerical simulation principles and the concept of one-turn periodic maps. In Chapter 3, the discussion becomes more focused with the introduction of differential algebras. The most critical test for differential algebraic mapping techniques -- their application to long-term stability studies -- is discussed in Chapter 4. Chapter 5 presents a discussion of differential algebraic treatment of dispersed betatron motion. The paper concludes in Chapter 6 with a discussion of parameterization of high-order maps.

  4. Neutron single particle structure in 131Sn and the r-process

    SciTech Connect

    Kozub, R. L.; Bardayan, Daniel W; Adekola, Aderemi S; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Hatarik, Robert; Jones, K. L.; Krolas, W.; Liang, J Felix; Ma, Zhanwen; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; Pain, Steven D; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott; Swan, T. P.

    2009-01-01

    Recent calculations suggest that, at late times in the r-process, the rate of neutron capture by {sup 130}Sn has a significant impact on nucleosynthesis. Direct capture into low-lying bound states is likely the dominant reaction in the r-process near the N=82 closed shell, so reaction rates are strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, we have acquired (d,p) reaction data in the A{approx}132 region in inverse kinematics using {approx}630 MeV beams (4.85 MeV/u for {sup 130}Sn) and CD{sub 2} targets. An array of Si strip detectors, including SIDAR and an early implementation of the new Oak Ridge Rutgers University Barrel Array (ORRUBA), was used to detect reaction products. Preliminary results for the {sup 130}Sn(d,p){sup 131}Sn experiment are reported.

  5. Single particle transport in two-dimensional heterojunction interlayer tunneling field effect transistor

    SciTech Connect

    Li, Mingda Snider, Gregory; Jena, Debdeep; Grace Xing, Huili; Esseni, David

    2014-02-21

    The single particle tunneling in a vertical stack consisting of monolayers of two-dimensional semiconductors is studied theoretically, and its application to a novel Two-dimensional Heterojunction Interlayer Tunneling Field Effect Transistor (Thin-TFET) is proposed and described. The tunneling current is calculated by using a formalism based on the Bardeen's transfer Hamiltonian, and including a semi-classical treatment of scattering and energy broadening effects. The misalignment between the two 2D materials is also studied and found to influence the magnitude of the tunneling current but have a modest impact on its gate voltage dependence. Our simulation results suggest that the Thin-TFETs can achieve very steep subthreshold swing, whose lower limit is ultimately set by the band tails in the energy gaps of the 2D materials produced by energy broadening. The Thin-TFET is thus very promising as a low voltage, low energy solid state electronic switch.

  6. Visualizing interactions between Sindbis virus and cells by single particle tracking

    NASA Astrophysics Data System (ADS)

    Williard, Mary

    2005-03-01

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

  7. Stability of Single Particle Motion with Head-On Beam-Beam Compensation in the RHIC

    SciTech Connect

    Luo,Y.; Fischer, W.; Abreu, N.

    2008-05-01

    To compensate the large tune shift and tune spread generated by the head-on beam-beam interactions in the polarized proton run in the Relativistic Heavy Ion Collider (RHIC), we proposed a low energy electron beam with a Gaussian transverse profiles to collide head-on with the proton beam. In this article, with a weak-strong beam-beam interaction model, we investigate the stability of single particle motion in the presence of head-on beam-beam compensation. Tune footprints, tune diffusion, Lyapunov exponents, and 10{sup 6} turn dynamic apertures are calculated and compared between the cases without and with beam-beam compensation. A tune scan is performed and the possibility of increasing the bunch intensity is studied. The cause of tune footprint foldings is discussed, and the tune diffusion and Lyapunov exponent analysis are compared.

  8. Exponential orthogonality catastrophe in single-particle and many-body localized systems

    NASA Astrophysics Data System (ADS)

    Deng, Dong-Ling; Pixley, J. H.; Li, Xiaopeng; Das Sarma, S.

    2015-12-01

    We investigate the statistical orthogonality catastrophe (STOC) in single-particle and many-body localized systems by studying the response of the many-body ground state to a local quench. Using scaling arguments and exact numerical calculations, we establish that the STOC gives rise to a wave function overlap between the pre- and postquench ground states that has an exponential decay with the system size, in sharp contrast to the well-known power law Anderson orthogonality catastrophe in metallic systems. This exponential decay arises from a statistical charge transfer process where a particle can be effectively "transported" to an arbitrary lattice site. In a many-body localized phase, this nonlocal transport and the associated exponential STOC phenomenon persist in the presence of interactions. We study the possible experimental consequences of the exponential STOC on the Loschmidt echo and spectral function, establishing that this phenomenon might be observable in cold atomic experiments through Ramsey interference and radio-frequency spectroscopy.

  9. Analysis and differentiation of mineral dust by single particle laser mass spectrometry

    SciTech Connect

    Gallavardin, S. J.; Lohmann, U.; Cziczo, Daniel J.

    2008-05-09

    Abstract This study evaluates the potential of single particle laser desorption/ionization mass spectrometry for the analysis of atmospherically relevant mineral dusts. Samples of hematite, goethite, calcium carbonate, calcium sulfate, silica, quartz, montmorrillonite, kaolinite, illite, hectorite, wollastonite and nephelinsyenit were investigated in positive and negative ion mode with a monopolar time-of-flight mass spectrometer where the desorption/ionization step was performed with a 193 nm excimer laser (~109 W/cm2). Particle size ranged from 500 nm to 3 μm. Positive mass spectra mainly provide elemental composition whereas negative ion spectra provide information on element speciation and of a structural nature. The iron oxide, calcium-rich and aluminosilicate nature of particles is established in positive ion mode. The differentiation of calcium materials strongly relies on the calcium counter-ions in negative mass spectra. Aluminosilicates can be differentiated in both positive and negative ion mode using the relative abundance of various aluminum and silicon ions.

  10. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins

    PubMed Central

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; Van Dyck, Dirk; Chen, Fu-Rong

    2016-01-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images. PMID:27292544

  11. Interference and multiparticle effects in a Mach-Zehnder interferometer with single-particle sources

    NASA Astrophysics Data System (ADS)

    Rosselló, Guillem; Battista, Francesca; Moskalets, Michael; Splettstoesser, Janine

    2015-03-01

    We investigate a Mach-Zehnder interferometer fed by two time-dependently driven single-particle sources, one of them placed in front of the interferometer, the other in the center of one of the arms. As long as the two sources are operated independently, the signal at the output of the interferometer shows an interference pattern, which we analyze in the spectral current, in the charge and energy currents, as well as in the charge current noise. The synchronization of the two sources in this specifically designed setup allows for collisions and absorptions of particles at different points of the interferometer, which have a strong impact on the detected signals. It introduces further relevant time scales and can even lead to a full suppression of the interference in some of the discussed quantities. The complementary interpretations of this phenomenon in terms of spectral properties and tunable two-particle effects (absorptions and quantum exchange effects) are put forward in this paper.

  12. Single particle momentum and angular distributions in hadron-hadron collisions at ultrahigh energies

    NASA Technical Reports Server (NTRS)

    Chou, T. T.; Chen, N. Y.

    1985-01-01

    The forward-backward charged multiplicity distribution (P n sub F, n sub B) of events in the 540 GeV antiproton-proton collider has been extensively studied by the UA5 Collaboration. It was pointed out that the distribution with respect to n = n sub F + n sub B satisfies approximate KNO scaling and that with respect to Z = n sub F - n sub B is binomial. The geometrical model of hadron-hadron collision interprets the large multiplicity fluctuation as due to the widely different nature of collisions at different impact parameters b. For a single impact parameter b, the collision in the geometrical model should exhibit stochastic behavior. This separation of the stochastic and nonstochastic (KNO) aspects of multiparticle production processes gives conceptually a lucid and attractive picture of such collisions, leading to the concept of partition temperature T sub p and the single particle momentum spectrum to be discussed in detail.

  13. 4D scanning transmission ultrafast electron microscopy: Single-particle imaging and spectroscopy.

    PubMed

    Ortalan, Volkan; Zewail, Ahmed H

    2011-07-20

    We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging. PMID:21615171

  14. Glass formers display universal non-equilibrium dynamics on the level of single-particle jumps

    NASA Astrophysics Data System (ADS)

    Helfferich, J.; Vollmayr-Lee, K.; Ziebert, F.; Meyer, H.; Baschnagel, J.

    2015-02-01

    Glasses are inherently out-of-equilibrium systems evolving slowly toward their equilibrium state in a process called physical aging. During aging, dynamic observables depend on the history of the system, hampering comparative studies of dynamics in different glass formers. Here, we demonstrate how glass formers can be directly compared on the level of single-particle jumps, i.e. the structural relaxation events underlying the α-process. Describing the dynamics in terms of a continuous-time random walk, an analytic prediction for the jump rate is derived. The result is subsequently compared to molecular-dynamics simulations of amorphous silica and a polymer melt as two generic representatives of strong and fragile glass formers, and good agreement is found.

  15. Time irreversibility of the statistics of a single particle in compressible turbulence.

    PubMed

    Grafke, Tobias; Frishman, Anna; Falkovich, Gregory

    2015-04-01

    We investigate time irreversibility from the point of view of a single particle in Burgers turbulence. Inspired by the recent work for incompressible flows [Xu et al., Proc. Natl. Acad. Sci. USA 111, 7558 (2014)], we analyze the evolution of the kinetic energy for fluid markers and use the fluctuations of the instantaneous power as a measure of time irreversibility. For short times, starting from a uniform distribution of markers, we find the scaling 〈[E(t)-E(0)](n)〉∝t and 〈p(n)〉∝Re(n-1) for the power as a function of the Reynolds number. Both observations can be explained using the "flight-crash" model, suggested by Xu et al. Furthermore, we use a simple model for shocks that reproduces the moments of the energy difference, including the pre-factor for 〈E(t)-E(0)〉. To complete the single-particle picture for Burgers we compute the moments of the Lagrangian velocity difference and show that they are bifractal. This arises in a similar manner to the bifractality of Eulerian velocity differences. In the above setting, time irreversibility is directly manifest as particles eventually end up in shocks. We additionally investigate time irreversibility in the long-time limit when all particles are located inside shocks and the Lagrangian velocity statistics are stationary. We find the same scalings for the power and energy differences as at short times and argue that this is also a consequence of rare "flight-crash" events related to shock collisions. PMID:25974595

  16. ClusterSculptor: Software for Expert-Steered Classification of Single Particle Mass Spectra

    SciTech Connect

    Zelenyuk, Alla; Imre, Dan G.; Nam, Eun Ju; Han, Yiping; Mueller, Klaus

    2008-08-01

    To take full advantage of the vast amount of highly detailed data acquired by single particle mass spectrometers requires that the data be organized according to some rules that have the potential to be insightful. Most commonly statistical tools are used to cluster the individual particle mass spectra on the basis of their similarity. Cluster analysis is a powerful strategy for the exploration of high-dimensional data in the absence of a-priori hypotheses or data classification models, and the results of cluster analysis can then be used to form such models. More often than not, when examining the data clustering results we find that many clusters contain particles of different types and that many particles of one type end up in a number of separate clusters. Our experience with cluster analysis shows that we have a vast amount of non-compiled knowledge and intuition that should be brought to bear in this effort. We will present new software we call ClusterSculptor that provides comprehensive and intuitive framework to aid scientists in data classification. ClusterSculptor uses k-means as the overall clustering engine, but allows tuning its parameters interactively, based on a non-distorted compact visual presentation of the inherent characteristics of the data in high-dimensional space. ClusterSculptor provides all the tools necessary for a high-dimensional activity we call cluster sculpting. ClusterSculptor is designed to be coupled to SpectraMiner, our data mining and visualization software package. The data are first visualized with SpectraMiner and identified problems are exported to ClusterSculptor, where the user steers the reclassification and recombination of clusters of tens of thousands particle mass spectra in real-time. The resulting sculpted clusters can be then imported back into SpectraMiner. Here we will greatly improved single particle chemical speciation in an example of application of this new tool to a number of particle types of atmospheric

  17. Fabrication of bright and small size semiconducting polymer nanoparticles for cellular labelling and single particle tracking

    NASA Astrophysics Data System (ADS)

    Wei, Lin; Zhou, Peng; Yang, Qingxiu; Yang, Qiaoyu; Ma, Ming; Chen, Bo; Xiao, Lehui

    2014-09-01

    In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance.In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance. Electronic supplementary information (ESI) available: Experimental section and additional supporting results as noted in the text

  18. The single-particle structure around ^132Sn explored through the (d,p) reaction

    NASA Astrophysics Data System (ADS)

    Jones, Kate

    2007-04-01

    The nuclear shell model^1, originally developed by Maria Geoppert Mayer in 1949 (Nobel Prize 1963) has been used extensively to explain the structure of nuclei. The atomic shell model describes the increased stability observed when an electron shell is filled. Correspondingly, nuclei with magic numbers of protons or neutrons (2, 8, 20, 28, 50, 82, 126) display additional stability. Only ten nuclei to date have been observed which have these standard magic numbers for both neutrons and protons, of these, half are stable or very long-lived. Many changes have been observed in nuclei as we move away from the valley of stability and it is important, both to nuclear structure physics and to understanding the synthesis of nuclei in the cosmos, to understand how these changes affect single-particle states.One exotic doubly-magic nucleus which can be produced with sufficient intensity to perform reactions on it is ^132Sn. Recent calculations^2 have shown that the structure around ^132Sn may affect the freeze out of the rapid neutron capture (r-)process, believed to occur in supernovae, which is responsible for the production of about half the nuclear species heavier than iron. By adding a neutron to a beam of ^132Sn via a transfer reaction, it is possible to study single-particle states beyond the double-shell closure. I will present results from a recent measurement of ^133Sn via the ^132Sn(d,p) reaction in inverse kinematics. [1] Maria Goeppert Mayer, Science 145 999 (1964). [2] R. Surman and J. Engel, Phys. Rev. C 64, 035801 (2001).

  19. Chikungunya virus fusion properties elucidated by single-particle and bulk approaches.

    PubMed

    van Duijl-Richter, Mareike K S; Blijleven, Jelle S; van Oijen, Antoine M; Smit, Jolanda M

    2015-08-01

    Chikungunya virus (CHIKV) is a rapidly spreading, enveloped alphavirus causing fever, rash and debilitating polyarthritis. No specific treatment or vaccines are available to treat or prevent infection. For the rational design of vaccines and antiviral drugs, it is imperative to understand the molecular mechanisms involved in CHIKV infection. A critical step in the life cycle of CHIKV is fusion of the viral membrane with a host cell membrane. Here, we elucidate this process using ensemble-averaging liposome-virus fusion studies, in which the fusion behaviour of a large virus population is measured, and a newly developed microscopy-based single-particle assay, in which the fusion kinetics of an individual particle can be visualised. The combination of these approaches allowed us to obtain detailed insight into the kinetics, lipid dependency and pH dependency of hemifusion. We found that CHIKV fusion is strictly dependent on low pH, with a threshold of pH 6.2 and optimal fusion efficiency below pH 5.6. At this pH, CHIKV fuses rapidly with target membranes, with typically half of the fusion occurring within 2 s after acidification. Cholesterol and sphingomyelin in the target membrane were found to strongly enhance the fusion process. By analysing our single-particle data using kinetic models, we were able to deduce that the number of rate-limiting steps occurring before hemifusion equals about three. To explain these data, we propose a mechanistic model in which multiple E1 fusion trimers are involved in initiating the fusion process. PMID:25872739

  20. In-situ imaging of reacting single-particle zeolites by non-linear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wrzesinski, Paul J.; Slipchenko, Mikhail N.; Zaman, Taslima A.; Rioux, Robert M.; Gord, James R.; Roy, Sukesh

    2015-03-01

    Zeolite catalysis has been exploited by the petrochemical industry since the 1940's for catalytic cracking reactions of long chain hydrocarbons. The selectivity of zeolites strongly depends on a pore size, which is controlled by the chosen structure-directing agent (SDA) and by the SDA decomposition/removal process. Although zeolites are composed of micron-sized crystals, studies of zeolite materials typically focus on bulk (i.e., ensemble) measurements to elucidate structure-function information or to optimize catalysts and/or process parameters. To examine these phenomena on the microscale, non-linear optical microscopy is used to provide real-time imaging of chemical reactions in zeolites at temperatures exceeding 400°C. The template decomposition mechanism is studied, as elucidation of the mechanism is critical to understanding the relationship between the decomposition chemistry and the nanoscale features of the zeolite (topology, Si/Al ratio, added dopants). Forward stimulated Raman scattering (SRS), forward coherent anti-Stokes Raman scattering (CARS) and epi two-photon fluorescence (TPF) modalities are acquired simultaneously providing video-rate structural and chemical information. A high-temperature cell with gas inlet system is used for the study of reactions under various temperatures and gas environments. Examining the decomposition process with single-particle resolution enables access to ensemble-level and spatially-resolved behavior. Parallel experiments on bulk zeolite powders are conducted to enable comparison of ensemble and single-particle behavior during template decomposition. Our multi-technique approach has high potential for gaining insight into the link between nanoscale structure and catalytic activity and selectivity of zeolitic materials.

  1. Characteristics of tyre dust in polluted air: Studies by single particle mass spectrometry (ATOFMS)

    NASA Astrophysics Data System (ADS)

    Dall'Osto, Manuel; Beddows, David C. S.; Gietl, Johanna K.; Olatunbosun, Oluremi A.; Yang, Xiaoguang; Harrison, Roy M.

    2014-09-01

    There is a paucity of quantitative knowledge on the contributions of non-exhaust (abrasion and re-suspension) sources to traffic emissions. Abrasive emissions can be broadly categorised as tyre wear, brake wear and road dust/road surface wear. Current research often considers road dust and tyre dust as externally mixed particles, the former mainly composed of mineral matter and the latter solely composed of mainly organic matter and some trace elements. The aim of this work was to characterise tyre wear from both laboratory and field studies by using Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS). Real-time single particle chemical composition was obtained from a set of rubber tyres rotating on a metal surface. Bimodal particle number size distributions peaking at 35 nm and 85 nm were obtained from SMPS/APS measurements over the range 6-20,000 nm. ATOFMS mass spectra of tyre wear in the particle size range 200-3000 nm diameter show peaks due to exo-sulphur compounds, nitrate, Zn and ions of high molecular weight (m/z > 100) attributed to organic polymers. Two large ATOFMS datasets collected from a number of outdoor studies were examined. The former was constituted of 48 road dust samples collected on the roads of London. The latter consisted of ATOFMS ambient air field studies from Europe, overall composed of more than 2,000,000 single particle mass spectra. The majority (95%) of tyre wear particles present in the road dust samples and atmospheric samples are internally mixed with metals (Li, Na, Ca, Fe, Ti), as well as phosphate. It is concluded that the interaction of tyres with the road surface creates particles internally mixed from two sources: tyre rubber and road surface materials. Measurements of the tyre rubber component alone may underestimate the contribution of tyre wear to concentrations of airborne particulate matter. The results presented are especially relevant for urban aerosol source apportionment and PM2.5 exposure assessment.

  2. Estimating the contribution of point sources to atmospheric metals using single-particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Snyder, David C.; Schauer, James J.; Gross, Deborah S.; Turner, Jay R.

    Single-particle mass spectra were collected using an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) during December of 2003 and February of 2004 at an industrially impacted location in East St. Louis, IL. Hourly integrated peak areas for twenty ions were evaluated for their suitability in representing metals/metalloids, particularly those reported in the US EPA Toxic Release Inventory (TRI). Of the initial twenty ions examined, six (Al, As, Cu, Hg, Ti, and V) were found to be unsuitable due to strong isobaric interferences with commonly observed organic fragments, and one (Be) was found to have no significant signal. The usability of three ions (Co, Cr, and Mn) was limited due to suspected isobaric interferences based on temporal comparisons with commonly observed organic fragments. The identity of the remaining ions (Sb, Ba, Cd, Ca, Fe, Ni, Pb, K, Se, and Zn) was substantiated by comparing their signals with the integrated hourly signals of one or more isotope ions. When compared with one-in-six day integrated elemental data as determined by X-ray fluorescence spectroscopy (XRF), the daily integrated ATOFMS signal for several metal ions revealed a semi-quantitative relationship between ATOFMS peak area and XRF concentrations, although in some cases comparison of these measurements were poor at low elemental concentrations/ion signals due to isobaric interferences. A method of estimating the impact of local point sources was developed using hourly integrated ATOFMS peak areas, and this method attributed as much as 85% of the concentration of individual metals observed at the study site to local point sources. Hourly surface wind data were used in conjunction with TRI facility emissions data to reveal likely point sources impacting metal concentrations at the study site and to illustrate the utility of using single-particle mass spectral data to characterize atmospheric metals and identify point sources.

  3. Quantum nonergodicity and fermion localization in a system with a single-particle mobility edge

    NASA Astrophysics Data System (ADS)

    Li, Xiaopeng; Pixley, J. H.; Deng, Dong-Ling; Ganeshan, Sriram; Das Sarma, S.

    2016-05-01

    We study the many-body localization aspects of single-particle mobility edges in fermionic systems. We investigate incommensurate lattices and random disorder Anderson models. Many-body localization and quantum nonergodic properties are studied by comparing entanglement and thermal entropy, and by calculating the scaling of subsystem particle-number fluctuations, respectively. We establish a nonergodic extended phase as a generic intermediate phase (between purely ergodic extended and nonergodic localized phases) for the many-body localization transition of noninteracting fermions where the entanglement entropy manifests a volume law (hence, "extended"), but there are large fluctuations in the subsystem particle numbers (hence, "nonergodic"). Based on the numerical results, we expect such an intermediate phase scenario may continue to hold even for the many-body localization in the presence of interactions as well. We find for many-body fermionic states in noninteracting one-dimensional Aubry-André and three-dimensional Anderson models that the entanglement entropy density and the normalized particle-number fluctuation have discontinuous jumps at the localization transition where the entanglement entropy is subthermal but obeys the "volume law." In the vicinity of the localization transition, we find that both the entanglement entropy and the particle-number fluctuations obey a single parameter scaling based on the diverging localization length. We argue using numerical and theoretical results that such a critical scaling behavior should persist for the interacting many-body localization problem with important observable consequences. Our work provides persuasive evidence in favor of there being two transitions in many-body systems with single-particle mobility edges, the first one indicating a transition from the purely localized nonergodic many-body localized phase to a nonergodic extended many-body metallic phase, and the second one being a transition

  4. Chemical characterization of freshly emitted particulate matter from aircraft exhaust using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Abegglen, Manuel; Brem, B. T.; Ellenrieder, M.; Durdina, L.; Rindlisbacher, T.; Wang, J.; Lohmann, U.; Sierau, B.

    2016-06-01

    Non-volatile aircraft engine emissions are an important anthropogenic source of soot particles in the upper troposphere and in the vicinity of airports. They influence climate and contribute to global warming. In addition, they impact air quality and thus human health and the environment. The chemical composition of non-volatile particulate matter emission from aircraft engines was investigated using single particle time-of-flight mass spectrometry. The exhaust from three different aircraft engines was sampled and analyzed. The soot particulate matter was sampled directly behind the turbine in a test cell at Zurich Airport. Single particle analyses will focus on metallic compounds. The particles analyzed herein represent a subset of the emissions composed of the largest particles with a mobility diameter >100 nm due to instrumental restrictions. A vast majority of the analyzed particles was shown to contain elemental carbon, and depending on the engine and the applied thrust the elemental carbon to total carbon ratio ranged from 83% to 99%. The detected metallic compounds were all internally mixed with the soot particles. The most abundant metals in the exhaust were Cr, Fe, Mo, Na, Ca and Al; V, Ba, Co, Cu, Ni, Pb, Mg, Mn, Si, Ti and Zr were also detected. We further investigated potential sources of the ATOFMS-detected metallic compounds using Inductively Coupled Plasma Mass Spectrometry. The potential sources considered were kerosene, engine lubrication oil and abrasion from engine wearing components. An unambiguous source apportionment was not possible because most metallic compounds were detected in several of the analyzed sources.

  5. A single-particle characterization of a mobile Versatile Aerosol Concentration Enrichment System for exposure studies

    PubMed Central

    Freney, Evelyn J; Heal, Mathew R; Donovan, Robert J; Mills, Nicholas L; Donaldson, Kenneth; Newby, David E; Fokkens, Paul HB; Cassee, Flemming R

    2006-01-01

    Background An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to investigate the size and chemical composition of fine concentrated ambient particles (CAPs) in the size range 0.2–2.6 μm produced by a Versatile Aerosol Concentration Enrichment System (VACES) contained within the Mobile Ambient Particle Concentrator Exposure Laboratory (MAPCEL). The data were collected during a study of human exposure to CAPs, in Edinburgh (UK), in February-March 2004. The air flow prior to, and post, concentration in the VACES was sampled in turn into the ATOFMS, which provides simultaneous size and positive and negative mass spectral data on individual fine particles. Results The particle size distribution was unaltered by the concentrator over the size range 0.2–2.6 μm, with an average enrichment factor during this study of ~5 (after dilution of the final air stream). The mass spectra from single particles were objectively grouped into 20 clusters using the multivariate K-means algorithm and then further grouped manually, according to similarity in composition and time sequence, into 8 main clusters. The particle ensemble was dominated by pure and reacted sea salt and other coarse inorganic dusts (as a consequence of the prevailing maritime-source climatology during the study), with relatively minor contributions from carbonaceous and secondary material. Very minor variations in particle composition were noted pre- and post-particle concentration, but overall there was no evidence of any significant change in particle composition. Conclusion These results confirm, via single particle analysis, the preservation of the size distribution and chemical composition of fine ambient PM in the size range 0.2–2.6 μm after passage through the VACES concentration instrumentation. PMID:16723024

  6. Empirical Investigation of Extreme Single-Particle Behavior of Nuclear Quadrupole Moments in Highly Collective A {approx} 150 Superdeformed Bands

    SciTech Connect

    Clark, S. T.; Hackman, G.; Janssens, R. V. F.; Clark, R. M.; Fallon, P.; Floor, S. N.; Lane, G. J.; Macchiavelli, A. O.; Norris, J.; Sanders, S. J.

    2001-10-22

    The intrinsic quadrupole moment Q{sub 0} of superdeformed rotational bands in A{approx}150 nuclei depends on the associated single-particle configuration. We have derived an empirical formula based on the additivity of effective quadrupole moments of single-particle orbitals that describes existing measurements from {sup 142}Sm to {sup 152}Dy . To further test the formula, the predicted Q{sub 0} moments for two superdeformed bands in {sup 146}Gd of 14.05 eb were confronted with a new measurement yielding 13.9{+-}0.4 eb and 13.9{+-}0.3 eb , respectively. This excellent agreement provides empirical evidence of extreme single-particle behavior in highly deformed, collective systems.

  7. Fractional oscillator.

    PubMed

    Stanislavsky, A A

    2004-11-01

    We consider a fractional oscillator which is a generalization of the conventional linear oscillator in the framework of fractional calculus. It is interpreted as an ensemble average of ordinary harmonic oscillators governed by a stochastic time arrow. The intrinsic absorption of the fractional oscillator results from the full contribution of the harmonic oscillator ensemble: these oscillators differ a little from each other in frequency so that each response is compensated by an antiphase response of another harmonic oscillator. This allows one to draw a parallel in the dispersion analysis for media described by a fractional oscillator and an ensemble of ordinary harmonic oscillators with damping. The features of this analysis are discussed. PMID:15600586

  8. Phase-coexistence simulations of fluid mixtures by the Markov Chain Monte Carlo method using single-particle models

    SciTech Connect

    Li, Jun; Calo, Victor M.

    2013-09-15

    We present a single-particle Lennard–Jones (L-J) model for CO{sub 2} and N{sub 2}. Simplified L-J models for other small polyatomic molecules can be obtained following the methodology described herein. The phase-coexistence diagrams of single-component systems computed using the proposed single-particle models for CO{sub 2} and N{sub 2} agree well with experimental data over a wide range of temperatures. These diagrams are computed using the Markov Chain Monte Carlo method based on the Gibbs-NVT ensemble. This good agreement validates the proposed simplified models. That is, with properly selected parameters, the single-particle models have similar accuracy in predicting gas-phase properties as more complex, state-of-the-art molecular models. To further test these single-particle models, three binary mixtures of CH{sub 4}, CO{sub 2} and N{sub 2} are studied using a Gibbs-NPT ensemble. These results are compared against experimental data over a wide range of pressures. The single-particle model has similar accuracy in the gas phase as traditional models although its deviation in the liquid phase is greater. Since the single-particle model reduces the particle number and avoids the time-consuming Ewald summation used to evaluate Coulomb interactions, the proposed model improves the computational efficiency significantly, particularly in the case of high liquid density where the acceptance rate of the particle-swap trial move increases. We compare, at constant temperature and pressure, the Gibbs-NPT and Gibbs-NVT ensembles to analyze their performance differences and results consistency. As theoretically predicted, the agreement between the simulations implies that Gibbs-NVT can be used to validate Gibbs-NPT predictions when experimental data is not available.

  9. Local Optical Closure Using Single Particle Mixing State Observations during the 2010 DOE CARES Campaign

    NASA Astrophysics Data System (ADS)

    Zaveri, R. A.; Arnott, W. P.; Atkinson, D. B.; Barnard, J.; Beranek, J.; Cappa, C. D.; Chand, D.; Dubey, M. K.; Easter, R. C.; Flowers, B. A.; Gyawali, M. S.; Jobson, B. T.; Pekour, M. S.; Riemer, N. S.; Subramanian, R.; Song, C.; Zelenyuk, A.

    2011-12-01

    Atmospheric black carbon (BC) particles readily absorb both upwelling and downwelling broadband radiation and are thought to be second only to CO2 in contributing to global warming. However large uncertainties still exist in the global estimates of BC radiative forcing, which depend not only on our ability to accurately simulate the global loading and distribution of BC, but also on the precise knowledge of the mixing state and morphology of BC particles due to aging. To this end, one of the objectives of the Carbonaceous Aerosols and Radiative Effects Study (CARES) conducted in Sacramento, CA, during June 2010 was to investigate the evolution of urban BC particles and the associated optical properties, with the overarching goal of improving their process-level model representations. The daytime Sacramento urban plume was routinely transported to the northeast into the Sierra Nevada foothills area rich in biogenic emissions, and the aged aerosols were often recirculated back into the urban area the next morning. The CARES campaign observational strategy was designed to take advantage of this flow pattern by setting up two observation supersites - one located within the Sacramento urban area, referred to as the "T0 site," and another located about 24 km to the northeast in Cool, CA, a small town in the rural foothills area, referred to as the "T1 site." BC size distribution and mixing state were measured at both the sites with single particle soot photometry (SP2). The single particle mass spectrometer SPLAT II was also deployed at the T0 site to characterize the size, composition (mixing state), density, and morphology of BC and non-BC containing particles. Non-refractory aerosol species were measured by Aerodyne aerosol mass spectrometer (AMS). Aerosol light absorption and scattering (or extinction) at multiple wavelengths were measured using several techniques, including photoacoustic, cavity ring-down, nephelometer as well as the filter-based particle

  10. Online single particle measurements of black carbon coatings, structure and optical properties

    NASA Astrophysics Data System (ADS)

    Allan, James; Liu, Dantong; Taylor, Jonathan; Flynn, Michael; Williams, Paul; Morgan, William; Whitehead, James; Alfarra, Rami; McFiggans, Gordon; Coe, Hugh

    2016-04-01

    The impacts of black carbon on meteorology and climate remain a major source of uncertainty, owing in part to the complex relationship between the bulk composition of the particulates and their optical properties. A particular complication stems from how light interacts with particles in response to the microphysical configuration and any 'coatings', i.e. non-black carbon material that is either co-emitted or subsequently obtained through atmospheric processing. This may cause the particle to more efficiently absorb or scatter light and may even change the sign of its radiative forcing potential. While much insight has been gained through measurements of bulk aerosol properties, either while suspended or after collection on a filter or impactor substrate, this does not provide a complete picture and thus may not adequately constrain the system. Here we present an overview of recent work to better constrain the properties of black carbon using online, in situ measurements of single particles, primarily using a Single Particle Soot Photometer (SP2). We have developed novel methods of inverting the data produced and combining the different metrics derived so as to give the most effective insights into black carbon sources, processes and properties. We have also used this measurement in conjunction with other instruments (sometimes in series) and used the data to challenge many commonly used models of optical properties such as core-shell Mie, Rayleigh-Debeye-Gans and effective medium. This work has been carried out in a variety of atmospheric environments and with laboratory-produced soots, e.g. from a diesel engine rig. Highlights include the finding that with real-world atmospheric aerosols, bulk optical measurements may be insufficient to derive brown carbon parameters without detailed morphological data. We also show that the enhancement of absorption for both ambient and laboratory generated particles only occurs after the coating mass fraction reaches a certain

  11. Single particle characterization, source apportionment, and aging effects of ambient aerosols in Southern California

    NASA Astrophysics Data System (ADS)

    Shields, Laura Grace

    Composed of a mixture of chemical species and phases and existing in a variety of shapes and sizes, atmospheric aerosols are complex and can have serious influence on human health, the environment, and climate. In order to better understand the impact of aerosols on local to global scales, detailed measurements on the physical and chemical properties of ambient particles are essential. In addition, knowing the origin or the source of the aerosols is important for policymakers to implement targeted regulations and effective control strategies to reduce air pollution in their region. One of the most ground breaking techniques in aerosol instrumentation is single particle mass spectrometry (SPMS), which can provide online chemical composition and size information on the individual particle level. The primary focus of this work is to further improve the ability of one specific SPMS technique, aerosol time-of-flight mass spectrometry (ATOFMS), for the use of identifying the specific origin of ambient aerosols, which is known as source apportionment. The ATOFMS source apportionment method utilizes a library of distinct source mass spectral signatures to match the chemical information of the single ambient particles. The unique signatures are obtained in controlled source characterization studies, such as with the exhaust emissions of heavy duty diesel vehicles (HDDV) operating on a dynamometer. The apportionment of ambient aerosols is complicated by the chemical and physical processes an individual particle can undergo as it spends time in the atmosphere, which is referred to as "aging" of the aerosol. Therefore, the performance of the source signature library technique was investigated on the ambient dataset of the highly aged environment of Riverside, California. Additionally, two specific subsets of the Riverside dataset (ultrafine particles and particles containing trace metals), which are known to cause adverse health effects, were probed in greater detail. Finally

  12. Foucault and the Imperatives of Education: Critique and Self-Creation in a Non-Foundational World

    ERIC Educational Resources Information Center

    Olssen, Mark

    2006-01-01

    This article outlines Foucault's conception of critique in relation to his writings on Kant. In that Kant saw Enlightenment as a process of release from the status of immaturity in that we accept someone else's authority to lead us in areas where the use of reason is called for, it is claimed in this article that Foucault's notion of critique…

  13. Transformation of a Foucault shadowgram into the geometrical model of a shear interferogram by means of isophotometry

    NASA Astrophysics Data System (ADS)

    Zhevlakov, A. P.; Zatsepina, M. E.; Kirillovskii, V. K.

    2014-06-01

    The principles of transformation of a Foucault shadowgram into a quantitative map of wave-front deformation based on creation of a system of isophotes are unveiled. The presented studies and their results prove that there is a high degree of correspondence between a Foucault shadowgram and the geometrical model of a shear interferogram with respect to displaying wave-front deformations.

  14. The ESyS_Particle: A New 3-D Discrete Element Model with Single Particle Rotation

    NASA Astrophysics Data System (ADS)

    Wang, Yucang; Mora, Peter

    In this paper, the Discrete Element Model (DEM) is reviewed, and the ESyS_Particle, our new version of DEM, is introduced. We particularly highlight some of the major physical concerns about DEMs and major differences between our model and most current DEMs. In the new model, single particle rotation is introduced and represented by a unit quaternion. For each 3-D particle, six degrees of freedom are employed: three for translational motion, and three for orientation. Six kinds of relative motions are permitted between two neighboring particles, and six interactions are transferred, i.e., radial, two shearing forces, twisting and two bending torques. The relative rotation between two particles is decomposed into two sequence-independent rotations such that all interactions due to the relative motions between interactive rigid bodies can be uniquely determined. This algorithm can give more accurate results because physical principles are obeyed. A theoretical analysis about how to choose the model parameters is presented. Several numerical tests have been carried out, the results indicate that most laboratory tests can be well reproduced using our model.

  15. Single Particle Tracking Reveals that EGFR Signaling Activity Is Amplified in Clathrin-Coated Pits

    PubMed Central

    Ibach, Jenny; Radon, Yvonne; Gelléri, Márton; Sonntag, Michael H.; Brunsveld, Luc; Bastiaens, Philippe I. H.; Verveer, Peter J.

    2015-01-01

    Signaling from the epidermal growth factor receptor (EGFR) via phosphorylation on its C-terminal tyrosine residues requires self-association, which depends on the diffusional properties of the receptor and its density in the plasma membrane. Dimerization is a key event for EGFR activation, but the role of higher order clustering is unknown. We employed single particle tracking to relate the mobility and aggregation of EGFR to its signaling activity. EGFR mobility alternates between short-lived free, confined and immobile states. In the immobile state, EGFR tends to aggregate in clathrin-coated pits, which is further enhanced in a phosphorylation-dependent manner and does not require ligand binding. EGFR phosphorylation is further amplified by cross-phosphorylation in clathrin-coated pits. Because phosphorylated receptors can escape from the pits, local gradients of signaling active EGFR are formed. These results show that amplification of EGFR phosphorylation by receptor clustering in clathrin-coated pits supports signal activation at the plasma membrane. PMID:26575183

  16. Detecting and Quantifying Colocalization of Cell Surface Molecules by Single Particle Fluorescence Imaging

    PubMed Central

    Morrison, Ian E. G.; Karakikes, Ioannis; Barber, Rosamund E.; Fernández, Nelson; Cherry, Richard J.

    2003-01-01

    Single particle fluorescence imaging (SPFI) uses the high sensitivity of fluorescence to visualize individual molecules that have been selectively labeled with small fluorescent particles. The positions of particles are determined by fitting the intensity profile of their images to a 2-D Gaussian function. We have exploited the positional information obtained from SPFI to develop a method for detecting colocalization of cell surface molecules. This involves labeling two different molecules with different colored fluorophores and determining their positions separately by dual wavelength imaging. The images are analyzed to quantify the overlap of the particle images and hence determine the extent of colocalization of the labeled molecules. Simulated images and experiments with a model system are used to investigate the extent to which colocalization occurs from chance proximity of randomly distributed molecules. A method of correcting for positional shifts that result from chromatic aberration is presented. The technique provides quantification of the extent of colocalization and can detect whether colocalized molecules occur singly or in clusters. We have obtained preliminary data for colocalization of molecules on intact cells. Cells often exhibit particulate autofluorescence that can interfere with the measurements; a method for overcoming this problem by triple wavelength imaging is described. PMID:14645098

  17. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  18. Qualitatively different collective and single-particle dynamics in a supercooled liquid.

    PubMed

    Priya, Madhu; Bidhoodi, Neeta; Das, Shankar P

    2015-12-01

    The equations of fluctuating nonlinear hydrodynamics for a two component mixture are obtained with a proper choice of slow variables which correspond to the conservation laws in the system. Using these nonlinear equations we construct the basic equations of the mode coupling theory (MCT) and consequent ergodic-nonergodic (ENE) transition in a binary mixture. The model is also analyzed in the one component limit of the mixture to study the dynamics of a tagged particle in the sea of identical particles. According to the existing MCT, dynamics of the single-particle correlation is slaved to that of the collective density fluctuations and, hence, both correlations freeze simultaneously at the ENE transition. We show here from a nonperturbative approach that at the ENE transition, characterized by the freezing of the long time limit of the dynamic correlation of collective density fluctuations to a nonzero value, the tagged-particle correlation still decays to zero. Our result implies that the point at which simulation or experimental data of the self-diffusion constant extrapolate to zero would not correspond to the ENE transition of simple MCT. PMID:26764693

  19. Single-Particle Chemical Composition in the Arctic during the Winter-Spring Transition

    NASA Astrophysics Data System (ADS)

    Pratt, K.; Kirpes, R.; Bondy, A. L.; Laskin, A.; Wang, B.; Ault, A. P.

    2015-12-01

    Atmospheric particles have significant, but highly uncertain, impacts on the Arctic climate by decreasing snow/ice albedo, scattering/absorbing solar radiation, nucleating cloud droplets and ice crystals, and contributing to atmospheric trace gas budgets. In the winter, atmospheric particles and trace gases are transported from the mid-latitudes to the Arctic, forming a springtime 'Arctic haze'. In the winter-spring, thinning sea ice is causing ice fracturing and the formation of open sea ice leads, which are suggested to be a source of local sea spray aerosol. To investigate the chemical composition and source of atmospheric aerosols during the winter-spring transition in the Arctic, 0.1-5 µm particles were collected during January and February 2014 near Barrow, Alaska. The elemental composition and morphology of these particles were examined using computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX). Significantly, major contributions of sea spray aerosol were observed for both submicron and supermicron size ranges during a nearby open lead event, and organic-sulfate ('Arctic haze') particles were also abundant at <1 µm in diameter. The single-particle chemical composition, sources, and evidence of aging processes will be discussed.

  20. SwarmPS: rapid, semi-automated single particle selection software.

    PubMed

    Woolford, David; Ericksson, Geoffery; Rothnagel, Rosalba; Muller, David; Landsberg, Michael J; Pantelic, Radosav S; McDowall, Alasdair; Pailthorpe, Bernard; Young, Paul R; Hankamer, Ben; Banks, Jasmine

    2007-01-01

    Single particle analysis (SPA) coupled with high-resolution electron cryo-microscopy is emerging as a powerful technique for the structure determination of membrane protein complexes and soluble macromolecular assemblies. Current estimates suggest that approximately 10(4)-10(5) particle projections are required to attain a 3A resolution 3D reconstruction (symmetry dependent). Selecting this number of molecular projections differing in size, shape and symmetry is a rate-limiting step for the automation of 3D image reconstruction. Here, we present Swarm(PS), a feature rich GUI based software package to manage large scale, semi-automated particle picking projects. The software provides cross-correlation and edge-detection algorithms. Algorithm-specific parameters are transparently and automatically determined through user interaction with the image, rather than by trial and error. Other features include multiple image handling (approximately 10(2)), local and global particle selection options, interactive image freezing, automatic particle centering, and full manual override to correct false positives and negatives. Swarm(PS) is user friendly, flexible, extensible, fast, and capable of exporting boxed out projection images, or particle coordinates, compatible with downstream image processing suites. PMID:16774837

  1. Orbital single particle tracking on a commercial confocal microscope using piezoelectric stage feedback

    NASA Astrophysics Data System (ADS)

    Lanzanò, L.; Gratton, E.

    2014-06-01

    Single Particle Tracking (SPT) is a technique used to locate fluorescent particles with nanometer precision. In the orbital tracking method the position of a particle is obtained analyzing the distribution of intensity along a circular orbit scanned around the particle. In combination with an active feedback this method allows tracking of particles in 2D and 3D with millisecond temporal resolution. Here we describe a SPT setup based on a feedback approach implemented with minimal modification of a commercially available confocal laser scanning microscope, the Zeiss LSM 510, in combination with an external piezoelectric stage scanner. The commercial microscope offers the advantage of a user-friendly software interface and pre-calibrated hardware components. The use of an external piezo-scanner allows the addition of feedback into the system but also represents a limitation in terms of its mechanical response. We describe in detail this implementation of the orbital tracking method and discuss advantages and limitations. As an example of application to live cell experiments we perform the 3D tracking of acidic vesicles in live polarized epithelial cells.

  2. Single particle optical investigation of gold shell enhanced upconverted fluorescence emission

    NASA Astrophysics Data System (ADS)

    Green, Kory; Lim, Shuang Fang; Hallen, Hans

    2014-03-01

    Upconverting nanoparticles (UCNPs) excited in the near IR offer novel advantages as fluorescent contrast agents, allowing for background free bio-imaging. However, their fluorescence brightness is hampered by low quantum efficiency due to the low absorption cross section of Ytterbium and Erbium ions in the near IR. We enhance the efficiency of these particles by investigating the plasmonic coupling of 30nm diameter core NaYF4: Yb, Er upconverting particles (UCNPs) with a gold shell coating. An enhancement of green emission by a factor of five and a three times overall increase in emission intensity has been achieved for single particle spectra. UV-Vis absorption has confirmed the surface plasmon resonance (SPR) of the gold shell to the near IR and transmission electron microscope (TEM) images demonstrates successful growth of a gold shell around the upconversion particle. Time-resolved spectroscopy shows that gold shell coupling changes the lifetime of the energy levels of the Erbium ion that are relevant to the emission process.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  4. Ambient particle characterization by single particle aerosol mass spectrometry in an urban area of Beijing

    NASA Astrophysics Data System (ADS)

    Li, Lei; Li, Mei; Huang, Zhengxu; Gao, Wei; Nian, Huiqing; Fu, Zhong; Gao, Jian; Chai, Fahe; Zhou, Zhen

    2014-09-01

    To investigate the composition and possible sources of aerosol particles in Beijing urban area, a single particle aerosol mass spectrometer (SPAMS) was deployed from April 22 to May 4, 2011. 510,341 particles out of 2,953,200 sized particles were characterized by SPAMS in combination with the ART-2a neural network algorithm. The particles were classified as rich-K (39.79%), carbonaceous species (32.7%), industry metal (19.2%), dust (5.7%), and rich-Na (1.76%). Industrial emissions related particles, rich-Fe, rich-Pb, and K-nitrate, were the major components of aerosol particles during haze periods, which were mainly from the steel plants and metal smelting processes around Beijing. Under stagnant meterological conditions, these regional emissions have a vital effect on haze formation. Organic carbon (OC) particles were attributed to biomass burning. NaK-EC was likely to come from local traffic emissions. Internally mixed organic and elemental carbon (OCEC) was found to be from possible sources of local traffic emission and biomass burning. It was found that coarse dust particles were mainly composed of four different types of dust particles, dust-Si, dust-Ca, dust-Al, and dust-Ti. It is the first time that SPAMS was used to study a dust storm in Beijing. Our results showed that SPAMS could be a powerful tool in the identification and apportionment of aerosol sources in Beijing, providing useful reference information for environmental control and management.

  5. Plasmon resonances in semiconductor materials for detecting photocatalysis at the single-particle level.

    PubMed

    Yan, Jiahao; Lin, Zhaoyong; Ma, Churong; Zheng, Zhaoqiang; Liu, Pu; Yang, Guowei

    2016-08-11

    Hot carriers, generated via the non-radiative decay of localized surface plasmon, can be utilized in photovoltaic and photocatalytic devices. In recent years, most studies have focused on conventional plasmon materials like Au and Ag. However, they suffer from several drawbacks like low energy of the generated hot carriers and a high charge-carrier recombination rate. To resolve these problems, here, we propose the plasmon resonances in heavily self-doped titanium oxide (TiO1.67) to realize effective hot carrier generation. Since the plasmon resonant energy of TiO1.67 nanoparticles (2.56 eV) is larger than the bandgap (2.15 eV), plasmon resonances through interband transition can realize both the generation and separation of hot carriers and bring a new strategy for visible-light photodegradation. The photodegradation rate for methyl orange was about 0.034 min(-1). More importantly, the combination of plasmonic and catalytic properties makes it feasible to investigate the degradation process of different materials and different structures at the single particle level in situ. By detecting the scattering shift, we demonstrated that the TiO1.67 dimer (Δλ/ΔλRIU = 0.16) possesses a higher photodegradation rate than an individual nanoparticle (Δλ/ΔλRIU = 0.09). We hope this finding may be a beginning, paving the way toward the development of semiconductor plasmonic materials for new applications beyond noble metals. PMID:27469299

  6. Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint

    SciTech Connect

    Edwards, C.F.; Marx, K.D.

    1991-06-01

    This paper explores the effects of particles statistics on the ability of a phase-Doppler system (or any single-particle diagnostic) to make accurate measurements of complex particle flows. This is accomplished by analyzing the response of an ideal phase-Doppler system to a postulated particle flux. The ideal system defined here senses particles of all sizes and velocities with perfect accuracy, but is subject to one constraint: in order for a measurement to be considered valid there must be only one particle in the probe volume at a time. A consequence of this constraint is that the measured flux of particles is similar to the true flux, but reduced by passage through two stages of filters. The first rejects particles for insufficient spacing and is controlled by a spatial Poisson process, while the second rejects particles for excessive residence time and is driven by a temporal Poisson process. The key filter parameters are the expected values of the number of particles in the probe volume and the number of particles entering the probe region during the residence time of a previous particle. Only if these values are kept below order 10{sup {minus}2} can the measured joint distribution function, flux rate, and derived quantities, be assumed to reflect the true nature of the flow. 8 refs., 30 figs., 2 tabs.

  7. Numerical analysis of single particle impact in the context of Cold Spray: a new adhesion model

    NASA Astrophysics Data System (ADS)

    Profizi, P.; Combescure, A.; Ogawa, K.

    2016-03-01

    A new adhesion model for numerical simulation of single particle impact in the context of Cold Spray is introduced. As in other studies, cohesive forces are put between the particle and substrate to account for adhesion. In this study however, the forces are put only when a local physical criterion is met. The physical phenomenon most often attributed to Cold Spray adhesion is a shear stress instability. The Johnson-Cook material law is used with a shear damage softening law to enable strong localization at the interface without the need for an extremely fine mesh. This localization is then detected as a drop in local yield stress value by the algorithm, which then implements a local cohesive force. The evolution of this cohesive force is defined by an energy dissipative cohesive model, using a surface adhesion energy as a material parameter. Each cohesive link is broken once all its associated surface energy is dissipated. A criterion on the damage value is also used to break a cohesive bond prematurely, to account for the effect of erosion at higher speeds. This model is found to reproduce the Cold Spray-like adhesion behavior with observed critical and maximum speeds.

  8. Optical microscopy as a comparative analytical technique for single-particle dissolution studies.

    PubMed

    Svanbäck, Sami; Ehlers, Henrik; Yliruusi, Jouko

    2014-07-20

    Novel, simple and cost effective methods are needed to replace advanced chemical analytical techniques, in small-scale dissolution studies. Optical microscopy of individual particles could provide such a method. The aim of the present work was to investigate and verify the applicability of optical microscopy as an analytical technique for drug dissolution studies. The evaluation was performed by comparing image and chemical analysis data of individual dissolving particles. It was shown that the data obtained by image analysis and UV-spectrophotometry produced practically identical dissolution curves, with average similarity and difference factors above 82 and below 4, respectively. The relative standard deviation for image analysis data, of the studied particle size range, varied between 1.9% and 3.8%. Consequently, it is proposed that image analysis can be used, on its own, as a viable analytical technique in single-particle dissolution studies. The possibility for significant reductions in sample preparation, operational cost, time and substance consumption gives optical detection a clear advantage over chemical analytical methods. Thus, image analysis could be an ideal and universal analytical technique for rapid small-scale dissolution studies. PMID:24751345

  9. Formation of nanowires via single particle-triggered linear polymerization of solid-state aromatic molecules.

    PubMed

    Horio, Akifumi; Sakurai, Tsuneaki; Lakshmi, G B V S; Kumar Avasthi, Devesh; Sugimoto, Masaki; Yamaki, Tetsuya; Seki, Shu

    2016-08-11

    Nanowires occupy a prestigious place in nanoelectronics, nanomechanics, and biomimetics. Although there are notable methods to grow nanowires via self-assembly, there is a key drawback in the need to find out the specific conditions appropriate for each system. In this sense, universal techniques to fabricate such nanowires from various organic materials have been sought for the continued progress of the related research field. Here we report one of the promising and facile methodologies to quantitatively produce nanowires with controlled geometrical parameters. In this method, referred to as "Single Particle-Triggered Linear Polymerization (STLiP)", organic thin films on a supporting substrate were irradiated with high-energy charged particles, accelerated by particle accelerators. Each particle penetrates from the top of the films to the substrate while gradually releasing kinetic energy along its trajectory (ion track), generating reactive intermediates such as radical species that eventually induce propagation reactions. The resulting polymerized products were integrated into nanowires with uniform diameter and length that can be isolated via development with appropriate organic solvents. Considering the widely applicable nature of STLiP to organic materials, the present technique opens a new door for access to a number of functional nanowires and their assembly. PMID:27355341

  10. Accelerators for critical experiments involving single-particle upset in solid-state microcircuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1985-01-01

    Charged-particle interactions in microelectronic circuit chips (integrated circuits) present a particularly insidious problem for solid-state electronic systems due to the generation of soft errors or single-particle event upset (SEU) by either cosmic rays or other radiation sources. Particle accelerators are used to provide both light and heavy ions in order to assess the propensity of integrated circuit chips for SEU. Critical aspects of this assessment involve the ability to analytically model SEU for the prediction of error rates in known radiation environments. In order to accurately model SEU, the measurement and prediction of energy deposition in the form of an electron-hole plasma generated along an ion track is of paramount importance. This requires the use of accelerators which allow for ease in both energy control (change of energy) and change of ion species. This and other aspects of ion-beam control and diagnostics (e.g., uniformity and flux) are of critical concern for the experimental verification of theoretical SEU models.

  11. Single Particle Transport Through Carbon Nanotube Wires: Effect of Defects and Polyhedral Cap

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Govidan, T. R.

    1999-01-01

    The ability to manipulate carbon nanotubes with increasing precision has enabled a large number of successful electron transport experiments. These studies have primarily focussed on characterizing transport through both metallic and semiconducting wires. Tans et al. demonstrated ballistic transport in single-wall nanotubes for the first time, although the experimental configuration incurred large contact resistance. Subsequently, methods of producing low contact resistances have been developed and two terminal conductances smaller than 50 k-ohms have been repeatably demonstrated in single-wall and multi-wall nanotubes. In multi-wall nanotubes, Frank et al. demonstrated a resistance of approximately h/2e(exp 2) in a configuration where the outermost layer made contact to a liquid metal. This was followed by the work of de Pablo et al. where a resistance of h(bar)/27e(exp 2) (approximately 478 ohms) was measured in a configuration where electrical contact was made to many layers of a multi-wall nanotube. Frank et al. and Pablo et al. note that each conducting layer contributes a conductance of only 2e(exp 2)/h, instead of the 4e(exp 2)/h that a single particle mode counting picture yields. These small resistances have been obtained in microns long nanotubes, making them the best conducting molecular wires to date. The large conductance of nanotube wires stems from the fact that the crossing bands of nanotubes are robust to defect scattering.

  12. Single-Particle Spectroscopy Reveals Heterogeneity in Electrochemical Tuning of the Localized Surface Plasmon

    PubMed Central

    2015-01-01

    A hyperspectral imaging method was developed that allowed the identification of heterogeneous plasmon response from 50 nm diameter gold colloidal particles on a conducting substrate in a transparent three-electrode spectroelectrochemical cell under non-Faradaic conditions. At cathodic potentials, we identified three distinct behaviors from different nanoparticles within the same sample: irreversible chemical reactions, reversible chemical reactions, and reversible charge density tuning. The irreversible reactions in particular would be difficult to discern in alternate methodologies. Additional heterogeneity was observed when single nanoparticles demonstrating reversible charge density tuning in the cathodic regime were measured dynamically in anodic potential ranges. Some nanoparticles that showed charge density tuning in the cathodic range also showed signs of an additional chemical tuning mechanism in the anodic range. The expected changes in nanoparticle free-electron density were modeled using a charge density-modified Drude dielectric function and Mie theory, a commonly used model in colloidal spectroelectrochemistry. Inconsistencies between experimental results and predictions of this common physical model were identified and highlighted. The broad range of responses on even a simple sample highlights the rich experimental and theoretical playgrounds that hyperspectral single-particle electrochemistry opens. PMID:24971712

  13. Qualitatively different collective and single-particle dynamics in a supercooled liquid

    NASA Astrophysics Data System (ADS)

    Priya, Madhu; Bidhoodi, Neeta; Das, Shankar P.

    2015-12-01

    The equations of fluctuating nonlinear hydrodynamics for a two component mixture are obtained with a proper choice of slow variables which correspond to the conservation laws in the system. Using these nonlinear equations we construct the basic equations of the mode coupling theory (MCT) and consequent ergodic-nonergodic (ENE) transition in a binary mixture. The model is also analyzed in the one component limit of the mixture to study the dynamics of a tagged particle in the sea of identical particles. According to the existing MCT, dynamics of the single-particle correlation is slaved to that of the collective density fluctuations and, hence, both correlations freeze simultaneously at the ENE transition. We show here from a nonperturbative approach that at the ENE transition, characterized by the freezing of the long time limit of the dynamic correlation of collective density fluctuations to a nonzero value, the tagged-particle correlation still decays to zero. Our result implies that the point at which simulation or experimental data of the self-diffusion constant extrapolate to zero would not correspond to the ENE transition of simple MCT.

  14. Mechanistic understanding of surface plasmon assisted catalysis on a single particle: cyclic redox of 4-aminothiophenol

    SciTech Connect

    Xu, Ping; Kang, Leilei; Mack, Nathan H.; Schanze, Kirk S.; Han, Xijiang; Wang, Hsing-Lin

    2013-10-21

    We investigate surface plasmon assisted catalysis (SPAC) reactions of 4-aminothiophenol (4ATP) to and back from 4,4'-dimercaptoazobenzene (DMAB) by single particle surface enhanced Raman spectroscopy, using a self-designed gas flow cell to control the reductive/oxidative environment over the reactions. Conversion of 4ATP into DMAB is induced by energy transfer (plasmonic heating) from surface plasmon resonance to 4ATP, where O2 (as an electron acceptor) is essential and H2O (as a base) can accelerate the reaction. In contrast, hot electron (from surface plasmon decay) induction drives the reverse reaction of DMAB to 4ATP, where H2O (or H2) acts as the hydrogen source. More interestingly, the cyclic redox between 4ATP and DMAB by SPAC approach has been demonstrated. Finally, this SPAC methodology presents a unique platform for studying chemical reactions that are not possible under standard synthetic conditions.

  15. Infinite single-particle bandwidth of a Mott-Hubbard insulator

    NASA Astrophysics Data System (ADS)

    Freericks, J. K.; Cohn, J. R.; van Dongen, P. G. J.; Krishnamurthy, H. R.

    2016-03-01

    The conventional viewpoint of the strongly correlated electron metal-insulator transition is that a single band splits into two upper and lower Hubbard bands at the transition. Much work has investigated whether this transition is continuous or discontinuous. Here we focus on another aspect and ask the question of whether there are additional upper and lower Hubbard bands, which stretch all the way out to infinity — leading to an infinite single-particle bandwidth (or spectral range) for the Mott insulator. While we are not able to provide a rigorous proof of this result, we use exact diagonalization studies on small clusters to motivate the existence of these additional bands, and we discuss some different methods that might be utilized to provide such a proof. Even though the extra upper and lower Hubbard bands have very low total spectral weight, those states are expected to have extremely long lifetimes, leading to a nontrivial contribution to the transport density of states for dc transport and modifying the high temperature limit for the electrical resistivity.

  16. Single particle tracking. Analysis of diffusion and flow in two-dimensional systems.

    PubMed Central

    Qian, H; Sheetz, M P; Elson, E L

    1991-01-01

    Analysis of the trajectories of small particles at high spatial and temporal resolution using video enhanced contrast microscopy provides a powerful approach to characterizing the mechanisms of particle motion in living cells and in other systems. We present here the theoretical basis for the analysis of these trajectories for particles undergoing random diffusion and/or systematic transport at uniform velocity in two-dimensional systems. The single particle tracking method, based on observations of the trajectories of individual particles, is compared with methods that characterize the motions of a large collection of particles such as fluorescence photobleaching recovery. Determination of diffusion coefficients or transport velocities either from correlation of positions or of velocities of the particles is discussed. A result of practical importance is an analysis of the dependence of the expected statistical uncertainty of these determinations on the number of position measurements. This provides a way of judging the accuracy of the diffusion coefficients and transport velocities obtained using this approach. PMID:1742458

  17. Investigating Single-Particle Structure in 26Na Using the New SHARC Array

    NASA Astrophysics Data System (ADS)

    Wilson, G. L.; Catford, W. N.; Diget, C. Aa.; Orr, N. A.; Matta, A.; Hackman, G.; Williams, S. J.; Simpson, E. C.; Celik, I. C.; Achouri, N. L.; Adsley, P.; Al-Falou, H.; Ashley, R.; Austin, R. A. E.; Ball, G. C.; Blackmon, J. C.; Boston, A. J.; Boston, H. C.; Brown, S. M.; Cross, D. S.; Djongolov, M.; Drake, T. E.; Hager, U.; Fox, S. P.; Fulton, B. R.; Galinski, N.; Garnsworthy, A. B.; Jamieson, D.; Kanungo, R.; Leach, K.; Orce, J. N.; Pearson, C. J.; Porter-Peden, M.; Sarazin, F.; Sjue, S.; Smalley, D.; Sumithrarachchi, C.; Triambak, S.; Unsworth, C.; Wadsworth, R.

    The changing of the nuclear shells for light, neutron-rich nuclei, and the single-particle nature of 26Na, has been explored by studying 25Na(d, p)26Na in inverse kinematics, using a beam of 25Na ions at 5 MeV per nucleon, provided by the ISAC-II facility at TRIUMF, Vancouver. Charged particles were detected with a highly-segmented silicon array that surrounded the 0.5 mg/cm2 (CD2)n target. Gamma rays from the recoiling 26Na nucleus were detected using eight Compton-suppressed HPGe clover detectors. Recoil tagging was provided by an in-beam scintillation foil, downstream of the germanium array. A novel technique of utilising pγ- and pγγ-gating to extract proton angular distributions from states populated close in energy was employed with success. New states in 26Na that are populated directly have been identified, using γ-decay patterns. Shell model calculations for comparison to experimental results are ongoing, using different model bases.

  18. Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations.

    PubMed

    Urahata, Sérgio M; Ribeiro, Mauro C C

    2005-01-01

    Ionic dynamics in room temperature molten salts (ionic liquids) containing 1-alkyl-3-methylimidazolium cations is investigated by molecular-dynamics simulations. Calculations were performed with united atom models, which were used in a previous detailed study of the equilibrium structure of ionic liquids [S. M. Urahata and M. C. C. Ribeiro, J. Chem. Phys. 120, 1855 (2004)]. The models were used in a systematic study of the dependency of several single particle time correlation functions on anion size (F-, Cl-, Br-, and PF6-) and alkyl chain length (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-). Despite of large mass and size of imidazolium cations, they exhibit larger mean-square displacement than anions. A further detailed picture of ionic motions is obtained by using appropriate projections of displacements along the plane or perpendicular to the plane of the imidazolium ring. A clear anisotropy in ionic displacement is revealed, the motion on the ring plane and almost perpendicular to the 1-alkyl chain being the less hindered one. Similar projections were performed on velocity correlation functions, whose spectra were used to relate short time ionic rattling with the corresponding long time diffusive regime. Time correlation functions of cation reorientation and dihedral angles of the alkyl chains are discussed, the latter decaying much faster than the former. A comparative physical picture of time scales for distinct dynamical processes in ionic liquids is provided. PMID:15638602

  19. Detection of Engineered Copper Nanoparticles in Soil Using Single Particle ICP-MS

    PubMed Central

    Navratilova, Jana; Praetorius, Antonia; Gondikas, Andreas; Fabienke, Willi; von der Kammer, Frank; Hofmann, Thilo

    2015-01-01

    Regulatory efforts rely on nanometrology for the development and implementation of laws regarding the incorporation of engineered nanomaterials (ENMs) into industrial and consumer products. Copper is currently one of the most common metals used in the constantly developing and expanding sector of nanotechnology. The use of copper nanoparticles in products, such as agricultural biocides, cosmetics and paints, is increasing. Copper based ENMs will eventually be released to the environment through the use and disposal of nano-enabled products, however, the detection of copper ENMs in environmental samples is a challenging task. Single particle inductively coupled plasma mass spectroscopy (spICP-MS) has been suggested as a powerful tool for routine nanometrology efforts. In this work, we apply a spICP-MS method for the detection of engineered copper nanomaterials in colloidal extracts from natural soil samples. Overall, copper nanoparticles were successfully detected in the soil colloidal extracts and the importance of dwell time, background removal, and sample dilution for method optimization and recovery maximization is highlighted. PMID:26690460

  20. Faster Convergence of Diffusion Anisotropy Detection by Three-Step Relation of Single-Particle Trajectory.

    PubMed

    Matsuda, Yu; Hanasaki, Itsuo; Iwao, Ryo; Yamaguchi, Hiroki; Niimi, Tomohide

    2016-04-19

    We focus on the issue of limited number of samples in the single particle tracking (SPT) when trying to extract the diffusion anisotropy that originates from the particle asymmetry. We propose a novel evaluation technique of SPT making use of the relation of the consecutive three steps. More specifically, the trend of the angle comprised of the three positions and the displacements are plotted on a scatter diagram. The particle anisotropy dependence of the shape of the scatter diagram is examined through the data from the standard numerical model of anisotropic two-dimensional Brownian motion. Comparison with the existing method reveals the faster convergence in the evaluation. In particular, our proposed method realizes the detection of diffusion anisotropy under the conditions of not only less number of data but also larger time steps. This is of practical importance not only when the abundant data is hard to achieve but also when the rotational diffusion is fast compared to the frame rate of the camera equipment, which tends to be more common for smaller particles or molecules of interest. PMID:26980574

  1. Single molecule λ-DNA stretching studied by microfluidics and single particle tracking

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Lu, Chang

    2007-10-01

    DNA stretching has been an intensively studied topic due to its involvement in the cellular functions. In this work, we studied DNA stretching based on microfluidics and single particle tracking techniques. Microfluidics generates well-defined flow field within microscale channels and potentially allows the incorporation of chemical and biological assays with the single molecule experiments. Single DNA molecules were tethered to the channel bottom (glass) at one end and to fluorescent microbeads at the other end. The microscale flow exerted hydrodynamic force on the microbead with a magnitude dependent on the flow rate. The force-extension curves of the single DNA molecules were obtained by localizing the fluorescent microbead with nanometer precision at different flow rates. We were able to obtain DNA force-extension curves which fit the wormlike chain model very well. Furthermore, we also observed plateaus at low forces (15-30pN) in these curves when the hydrodynamic force was kept constant for a duration of 10s at each flow rate. One possible reason is that stretching force with long duration lowers the activation barrier for the conformational changes of a double-stranded DNA molecule. We expect that this approach will be useful for studying the force associated with biological events involving single DNA molecules in general.

  2. Single-particle Lagrangian and structure statistics in kinematically simulated particle-laden turbulent flows

    NASA Astrophysics Data System (ADS)

    Murray, S.; Lightstone, M. F.; Tullis, S.

    2016-03-01

    Kinematic simulation (KS) is a means of generating a turbulent-like velocity field, in a manner that enforces a desired input Eulerian energy spectrum. Such models have also been applied in particle-laden flows, due to their ability to enforce spatial organization of the fluid velocity field when simulating the trajectories of individual Lagrangian particles. A critical evaluation of KS is presented; in particular, we examine its ability to reproduce single-particle Lagrangian statistics. Also the ability of KS to reproduce the preferential concentration of inertial particles is examined. Some computational results are presented, in which particles are transported alternatively by (1) turbulence generated by direct numerical simulation (DNS) of the incompressible Navier-Stokes equations, and (2) KS. The effect of unsteadiness formulation in particular is examined. We find that even steady KS qualitatively reproduces the continuity effect, clustering of inertial particles, the elevated dispersion of inertial particles over fluid particles, and the intermittency of Lagrangian velocity signals, but generally not to the same extent as is seen in the DNS.

  3. Ab initio approach to effective single-particle energies in doubly closed shell nuclei

    NASA Astrophysics Data System (ADS)

    Duguet, T.; Hagen, G.

    2012-03-01

    The present work discusses, from an ab initio standpoint, the definition, the meaning, and the usefulness of effective single-particle energies (ESPEs) in doubly closed shell nuclei. We perform coupled-cluster calculations to quantify to what extent selected closed-shell nuclei in the oxygen and calcium isotopic chains can effectively be mapped onto an effective independent-particle picture. To do so, we revisit in detail the notion of ESPEs in the context of strongly correlated many-nucleon systems and illustrate the necessity of extracting ESPEs through the diagonalization of the centroid matrix, as originally argued by Baranger. For the purpose of illustration, we analyze the impact of correlations on observable one-nucleon separation energies and nonobservable ESPEs in selected closed-shell oxygen and calcium isotopes. We then state and illustrate the nonobservability of ESPEs. Similarly to spectroscopic factors, ESPEs can indeed be modified by a redefinition of inaccessible quantities while leaving actual observables unchanged. This leads to the absolute necessity of employing consistent structure and reaction models based on the same nuclear Hamiltonian to extract the shell structure in a meaningful fashion from experimental data.

  4. Single Particle Chemical Speciation of Ambient Ultrafine Particulate Matter in Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Sipin, M. F.; Su, Y.; Prather, K. A.

    2002-12-01

    Ultrafine particles, particles with aerodynamic diameters lower than 100 nm, have recently gained increasing attention because of their hypothesized adverse heath effects and potential as cloud condensation nuclei. Chemical characterization of the ultrafine particles at the single particle level is important for assessing their impact on human health and understanding their formation and behavior. This is beneficial for modeling studies and regulations on pollution control. In August 2002, continuous ambient monitoring was performed in an industrial area in Atlanta, GA. Characterization of the urban particulate matter with aerodynamic diameters 30A›ƒ,ªƒ_o300 nm was carried out using a dual polarity aerosol time-of-flight mass spectrometer (ATOFMS) interfaced with an aerodynamic lens system. This configuration allows on-line real time simultaneous acquisition of size and chemical information for individual particles down to 30 nm. The ultrafine particles observed consisted of elemental carbon (EC), organic carbon (OC), and a mixture of OC and EC as a result of vehicular, industrial, and biogenic emissions. These major particle types, their associations with inorganics (i.e. ammonium, sulfate, nitrate, potassium, calcium, and metal oxides), and their temporal and size variations will be presented.

  5. Neutron single particle structure in 131Sn and direct neutron capture cross sections

    SciTech Connect

    Kozub, R. L.; Arbanas, Goran; Adekola, A. S.; Bardayan, Daniel W; Blackmon, Jeffery C; Chae, Kyung Yuk; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Hatarik, Robert; Hix, William Raphael; Jones, K. L.; Krolas, W.; Liang, J Felix; Ma, Z.; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; Pain, Steven D; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott; Swan, T. P.

    2012-01-01

    Recent calculations suggest that the rate of neutron capture by 130Sn has a significant impact on late-time nucleosynthesis in the r-process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r- process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d, p) reaction has been studied in inverse kinematics using a 630 MeV beam of 130Sn (4.8 MeV/u) and a (CD2)n target. An array of Si strip detectors, including SIDAR and an early implementation of the ORRUBA, was used to detect reaction products. Results for the 130Sn(d, p)131Sn reaction are found to be very similar to those from the previously reported 132Sn(d, p)133Sn reaction. Direct-semidirect (n, ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.

  6. Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations

    NASA Astrophysics Data System (ADS)

    Urahata, Sérgio M.; Ribeiro, Mauro C. C.

    2005-01-01

    Ionic dynamics in room temperature molten salts (ionic liquids) containing 1-alkyl-3-methylimidazolium cations is investigated by molecular-dynamics simulations. Calculations were performed with united atom models, which were used in a previous detailed study of the equilibrium structure of ionic liquids [S. M. Urahata and M. C. C. Ribeiro, J. Chem. Phys. 120, 1855 (2004)]. The models were used in a systematic study of the dependency of several single particle time correlation functions on anion size (F-, Cl-, Br-, and PF6-) and alkyl chain length (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-). Despite of large mass and size of imidazolium cations, they exhibit larger mean-square displacement than anions. A further detailed picture of ionic motions is obtained by using appropriate projections of displacements along the plane or perpendicular to the plane of the imidazolium ring. A clear anisotropy in ionic displacement is revealed, the motion on the ring plane and almost perpendicular to the 1-alkyl chain being the less hindered one. Similar projections were performed on velocity correlation functions, whose spectra were used to relate short time ionic rattling with the corresponding long time diffusive regime. Time correlation functions of cation reorientation and dihedral angles of the alkyl chains are discussed, the latter decaying much faster than the former. A comparative physical picture of time scales for distinct dynamical processes in ionic liquids is provided.

  7. Protein domain mapping by internal labeling and single particle electron microscopy.

    PubMed

    Ciferri, Claudio; Lander, Gabriel C; Nogales, Eva

    2015-11-01

    In recent years, electron microscopy (EM) and single particle analysis have emerged as essential tools for investigating the architecture of large biological complexes. When high resolution is achievable, crystal structure docking and de-novo modeling allows for precise assignment of individual protein domain sequences. However, the achievable resolution may limit the ability to do so, especially when small or flexible complexes are under study. In such cases, protein labeling has emerged as an important complementary tool to characterize domain architecture and elucidate functional mechanistic details. All labeling strategies proposed to date are either focused on the identification of the position of protein termini or require multi-step labeling strategies, potentially interfering with the final labeling efficiency. Here we describe a strategy for determining the position of internal protein domains within EM maps using a recombinant one-step labeling approach named Efficient Mapping by Internal Labeling (EMIL). EMIL takes advantage of the close spatial proximity of the GFP's N- and C-termini to generate protein chimeras containing an internal GFP at desired locations along the main protein chain. We apply this method to characterize the subunit domain localization of the human Polycomb Repressive Complex 2. PMID:26431894

  8. Single Particle Laser Mass Spectrometry Applied to Differential Ice Nucleation Experiments at the AIDA Chamber

    SciTech Connect

    Gallavardin, S. J.; Froyd, Karl D.; Lohmann, U.; Moehler, Ottmar; Murphy, Daniel M.; Cziczo, Dan

    2008-08-26

    Experiments conducted at the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) chamber located in Karlsruhe, Germany permit investigation of particle properties that affect the nucleation of ice at temperature and water vapor conditions relevant to cloud microphysics and climate issues. Ice clouds were generated by heterogeneous nucleation of Arizona test dust (ATD), illite, and hematite and homogeneous nucleation of sulfuric acid. Ice crystals formed in the chamber were inertially separated from unactivated, or ‘interstitial’ aerosol particles with a pumped counterflow virtual impactor (PCVI), then evaporated. The ice residue (i.e., the aerosol which initiated ice nucleation plus any material which was scavenged from the gas- and/or particle-phase), was chemically characterized at the single particle level using a laser ionization mass spectrometer. In this manner the species that first nucleated ice could be identified out of a mixed aerosol population in the chamber. Bare mineral dust particles were more effective ice nuclei (IN) than similar particles with a coating. Metallic particles from contamination in the chamber initiated ice nucleation before other species but there were few enough that they did not compromise the experiments. Nitrate, sulfate, and organics were often detected on particles and ice residue, evidently from scavenging of trace gas-phase species in the chamber. Hematite was a more effective ice nucleus than illite. Ice residue was frequently larger than unactivated test aerosol due to the formation of aggregates due to scavenging, condensation of contaminant gases, and the predominance of larger aerosol in nucleation.

  9. Single-particle measurements of phase partitioning between primary and secondary organic aerosols.

    PubMed

    Robinson, Ellis Shipley; Donahue, Neil M; Ahern, Adam T; Ye, Qing; Lipsky, Eric

    2016-07-18

    Organic aerosols provide a measure of complexity in the urban atmosphere. This is because the aerosols start as an external mixture, with many populations from varied local sources, that all interact with each other, with background aerosols, and with condensing vapors from secondary organic aerosol formation. The externally mixed particle populations start to evolve immediately after emission because the organic molecules constituting the particles also form thermodynamic mixtures - solutions - in which a large fraction of the constituents are semi-volatile. The external mixtures are thus well out of thermodynamic equilibrium, with very different activities for many constituents, and yet also have the capacity to relax toward equilibrium via gas-phase exchange of semi-volatile vapors. Here we describe experiments employing quantitative single-particle mass spectrometry designed to explore the extent to which various primary organic aerosol particle populations can interact with each other or with secondary organic aerosols representative of background aerosol populations. These methods allow us to determine when these populations will and when they will not mix with each other, and then to constrain the timescales for that mixing. PMID:27092377

  10. Investigating axial diffusion in cylindrical pores using confocal single-particle fluorescence correlation spectroscopy.

    PubMed

    Chen, Fang; Neupane, Bhanu; Li, Peiyuan; Su, Wei; Wang, Gufeng

    2016-08-01

    We explored the feasibility of using confocal fluorescence correlation spectroscopy to study small nanoparticle diffusion in hundred-nanometer-sized cylindrical pores. By modeling single particle diffusion in tube-like confined three-dimensional space aligned parallel to the confocal optical axis, we showed that two diffusion dynamics can be observed in both original intensity traces and the autocorrelation functions (ACFs): the confined two-dimensional lateral diffusion and the unconfined one-dimensional (1D) axial diffusion. The separation of the axial and confined lateral diffusion dynamics provides an opportunity to study diffusions in different dimensions separately. We further experimentally studied 45 nm carboxylated polystyrene particles diffusing in 300 nm alumina pores. The experimental data showed consistency with the simulation. To extract the accurate axial diffusion coefficient, we found that a 1D diffusion model with a Lorentzian axial collection profile needs to be used to analyze the experimental ACFs. The diffusion of the 45 nm nanoparticles in polyethyleneglycol-passivated 300 nm pores slowed down by a factor of ∼2, which can be satisfactorily explained by hydrodynamic frictions. PMID:27196052

  11. Classification of single particle optical scattering patterns by the spectrum enhancement algorithm

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.

    2005-11-01

    Airborne material particles in the 5μm size range have been collected, resuspended and analyzed by the TAOS (two-dimensional angular optical scattering) technique. The corresponding patterns of light intensity scattered by single particles have been automatically classified by an algorithm based on "spectrum enhancement", multivariate statistics and supervised optimization. The enhanced spectrum has resulted from some non-linear operations on fractional spatial derivatives of the pattern. It has yielded morphological descriptors of the pattern. A multiobjective optimization algorithm has included principal components analysis and has maximized pairwise discrimination between classes. The classifier has been trained by TAOS patterns from 10μm polystyrene spheres (P) and background aerosol particles (B). Then it has been applied to recognize patterns from airborne debris (A) sampled on a car racing track. Training with at least 10 patterns per class has discriminated P and B from A at confidence levels >=90%. Training by samples of smaller sizes (e.g., 5P and 12B patterns) has obviously yielded lower confidence levels (65% in B-A discrimination).

  12. Development of atomic layer deposition-activated microchannel plates for single particle detection at cryogenic temperatures

    SciTech Connect

    Gorelikov, Dmitry Sullivan, Neal; Rouffignac, Philippe de; Li, Huazhi; Narayanamoorthy, Jayasri; Tremsin, Anton S.

    2014-03-15

    Atomic layer deposition (ALD) technology is used to nanoengineer functional films inside the pores of microchannel plate (MCP) electron multipliers, enabling a novel MCP manufacturing technology that substantially improves performance and opens novel applications. The authors have developed custom tools and recipes for the growth of conformal films, with optimized conductance and secondary electron emission inside very long channels (∼6–20 μm diameter and >600 μm length, with tens of millions of channels per single MCP) by ALD. The unique ability to tune the characteristics of these ALD films enables their optimization to applications where time-resolved single particle imaging can be performed in extreme conditions, such as high counting rates at cryogenic temperatures. Adhesion of the conductive and emissive nanofilms to the 20 μm pore MCP glass substrates and their mechanical stability over a very wide range of temperatures (10–700 K) were confirmed experimentally. Resistance of ALD MCPs was reproducible during multiple cool-down cycles with no film degradation observed. Optimizing resistance of novel MCPs for operation at cryogenic temperature should enable high count rate event detection at temperatures below 20 K.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  14. A review of progress in single particle tracking: from methods to biophysical insights

    NASA Astrophysics Data System (ADS)

    Manzo, Carlo; Garcia-Parajo, Maria F.

    2015-12-01

    Optical microscopy has for centuries been a key tool to study living cells with minimum invasiveness. The advent of single molecule techniques over the past two decades has revolutionized the field of cell biology by providing a more quantitative picture of the complex and highly dynamic organization of living systems. Amongst these techniques, single particle tracking (SPT) has emerged as a powerful approach to study a variety of dynamic processes in life sciences. SPT provides access to single molecule behavior in the natural context of living cells, thereby allowing a complete statistical characterization of the system under study. In this review we describe the foundations of SPT together with novel optical implementations that nowadays allow the investigation of single molecule dynamic events with increasingly high spatiotemporal resolution using molecular densities closer to physiological expression levels. We outline some of the algorithms for the faithful reconstruction of SPT trajectories as well as data analysis, and highlight biological examples where the technique has provided novel insights into the role of diffusion regulating cellular function. The last part of the review concentrates on different theoretical models that describe anomalous transport behavior and ergodicity breaking observed from SPT studies in living cells.

  15. Neutron Single Particle Structure in Sn131 and Direct Neutron Capture Cross Sections

    NASA Astrophysics Data System (ADS)

    Kozub, R. L.; Arbanas, G.; Adekola, A. S.; Bardayan, D. W.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Erikson, L.; Hatarik, R.; Hix, W. R.; Jones, K. L.; Krolas, W.; Liang, J. F.; Ma, Z.; Matei, C.; Moazen, B. H.; Nesaraja, C. D.; Pain, S. D.; Shapira, D.; Shriner, J. F., Jr.; Smith, M. S.; Swan, T. P.

    2012-10-01

    Recent calculations suggest that the rate of neutron capture by Sn130 has a significant impact on late-time nucleosynthesis in the r process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r-process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d,p) reaction has been studied in inverse kinematics using a 630 MeV beam of Sn130 (4.8MeV/u) and a (CD2)n target. An array of Si strip detectors, including the Silicon Detector Array and an early implementation of the Oak Ridge Rutgers University Barrel Array, was used to detect reaction products. Results for the Sn130(d,​p)Sn131 reaction are found to be very similar to those from the previously reported Sn132(d,​p)Sn133 reaction. Direct-semidirect (n,γ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.

  16. Exponential Orthogonality Catastrophe in Single-Particle and Many-Body Localized Systems

    NASA Astrophysics Data System (ADS)

    Deng, Dong-Ling; Pixley, J. H.; Li, Xiaopeng

    We investigate the statistical orthogonality catastrophe (StOC) in single-particle and many-body localized systems by studying the response of the many-body ground state to a local quench. Using scaling arguments and exact numerical calculations, we establish that the StOC gives rise to a wave function overlap between the pre- and post-quench ground states that has an exponential decay with the system size, in sharp contrast to the well-known power law Anderson orthogonality catastrophe in metallic systems. This exponential decay arises from a statistical charge transfer process where a particle can be effectively ``transported'' to an arbitrary lattice site. We show that in a many-body localized phase, this non-local transport and the associated exponential StOC phenomenon persist in the presence of interactions. We study the possible experimental consequences of the exponential StOC on the Loschmidt echo and spectral function, establishing that this phenomenon might be observable in cold atomic experiments through Ramsey interference and radio-frequency spectroscopy. We thank S.-T. Wang, Z.-X. Gong, Y.-L. Wu, J. D. Sau, and Z. Ovadyahu for discussions. This work is supported by LPS-MPO-CMTC, JQI-NSF-PFC, and ARO-Atomtronics-MURI. The authors acknowledge the University of Maryland supercomputing resources.

  17. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  18. Neutron single particle structure in 131Sn and direct neutron capture cross sections.

    PubMed

    Kozub, R L; Arbanas, G; Adekola, A S; Bardayan, D W; Blackmon, J C; Chae, K Y; Chipps, K A; Cizewski, J A; Erikson, L; Hatarik, R; Hix, W R; Jones, K L; Krolas, W; Liang, J F; Ma, Z; Matei, C; Moazen, B H; Nesaraja, C D; Pain, S D; Shapira, D; Shriner, J F; Smith, M S; Swan, T P

    2012-10-26

    Recent calculations suggest that the rate of neutron capture by (130)Sn has a significant impact on late-time nucleosynthesis in the r process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r-process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d,p) reaction has been studied in inverse kinematics using a 630 MeV beam of (130)Sn (4.8 MeV/u) and a (CD(2))(n) target. An array of Si strip detectors, including the Silicon Detector Array and an early implementation of the Oak Ridge Rutgers University Barrel Array, was used to detect reaction products. Results for the (130)Sn(d, p)(131)Sn reaction are found to be very similar to those from the previously reported (132)Sn(d, p)(133)Sn reaction. Direct-semidirect (n,γ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates. PMID:23215181

  19. [Chemical Composition of the Single Particle Aerosol in Winter in Nanning Using SPAMS].

    PubMed

    Liu, Hui-lin; Song, Hong-jun; Chen, Zhi-ming; Huang, Jiong-li; Yang, Jun-chao; Mao, Jing-ying; Li, Hong; Liang, Gui-yun; Mo, Zhao-yu

    2016-02-15

    Single Particle Aerosol Mass Spectrometry (SPAMS) was performed to characterize the PM2.5 in Nanning from 15 to 24 February 2015. The correlation (R2) between the PM2.5 number concentration and the mass concentration of PM2.5 obtained using SPAMS was 0.76. The particle number concentration could reflect the atmospheric pollution situation to some degree. The Art-2a classification method was used to classify the chemical composition of PM2.5. The results showed that the principal chemical constituents were elemental carbon, organic elements carbon hybrid particles, organic carbon, rich potassium particles, mineral substance, rich sodium particles, second inorganic particles, levoglucosan and other heavy metals. Among them, the composition of elemental carbon was the highest, followed by organic carbon and rich potassium particles. The particle size of 80% of PM2.5 was mainly concentrated in the range of 0.2 microm to 1.0 microm with a peak value occurring at 0. 62 microm. The particle size distribution characteristics of different chemical components were similar. The number concentration of the chemical components in PM2.5 had the same variation tread with the mass concentration of PM2.5 over time. To a certain extent, the change in chemical composition could reflect the instantaneous pollution source. PMID:27363128

  20. Single particle refuse-derived fuel devolatilization: Experimental measurements of reaction products

    SciTech Connect

    Lai, Weichuan; Krieger-Brockett, B. . Dept. of Chemical Engineering)

    1993-11-01

    The authors present experimentally measured devolatilization product yields from single particles of refuse-derived fuel (RDF), a more uniform, transportable municipal solid waste. Disposal costs and environmental concerns have stimulated interest in thermochemical conversion of this material to chemicals and fuels. The composition, reaction conditions, and particle properties were systematically varied over the range found in practice to develop quantitative measures that rank the process controllables' influence on altering the product slate. Specialized regression methods and experimental designs enhanced the accuracy in view of the feed heterogeneity and offer a general method to extract real effects from experimental and sample noise''. The results have been verified successfully using actual commercial RDF and fabricated compositions that surpass those normally found in municipal waste to anticipate the influence of trends in recycling. The results show that the reaction conditions have a greater influence on altering fuel utilization and the relative yields of char, condensibles, and gases than does the composition over the range found in MSW and RDF.

  1. Melting of stripe phases and its signature in the single-particle spectral function

    NASA Astrophysics Data System (ADS)

    Raczkowski, Marcin; Assaad, Fakher F.

    2010-12-01

    Motivated by the recent experimental data [J. Fink, E. Schierle, E. Weschke, J. Geck, D. Hawthorn, V. Soltwisch, H. Wadati, H.-H. Wu, H. A. Dürr, N. Wizent, B. Büchner, and G. A. Sawatzky, Phys. Rev. B 79, 100502 (2009)10.1103/PhysRevB.79.100502] indicating the existence of a pure stripe charge order over unprecedently wide temperature range in La1.8-xEu0.2SrxCuO4 , we investigate the temperature-induced melting of the metallic stripe phase. In spite of taking into account local dynamic correlations within a real-space dynamical mean-field theory of the Hubbard model, we observe a mean-field-like melting of the stripe order irrespective of the choice of the next-nearest-neighbor hopping. The temperature dependence of the single-particle spectral function shows the stripe induced formation of a flat band around the antinodal points accompanied by the opening a gap in the nodal direction.

  2. On-Chip Magnetic Platform for Single-Particle Manipulation with Integrated Electrical Feedback.

    PubMed

    Monticelli, Marco; Torti, Andrea; Cantoni, Matteo; Petti, Daniela; Albisetti, Edoardo; Manzin, Alessandra; Guerriero, Erica; Sordan, Roman; Gervasoni, Giacomo; Carminati, Marco; Ferrari, Giorgio; Sampietro, Marco; Bertacco, Riccardo

    2016-02-17

    Methods for the manipulation of single magnetic particles have become very interesting, in particular for in vitro biological studies. Most of these studies require an external microscope to provide the operator with feedback for controlling the particle motion, thus preventing the use of magnetic particles in high-throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and detection of the transit of single particles. The proposed platform is based on zig-zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, the domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is also employed for detecting the bead transit. Indeed, the presence of the magnetic particle in suspension over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored through anisotropic magnetoresistance measurements, thus implementing an integrated electrical feedback of the bead transit. In particular, the individual manipulation and detection of single 1-μm sized beads is demonstrated. PMID:26707363

  3. Image processing for electron microscopy single-particle analysis using XMIPP

    PubMed Central

    Scheres, Sjors H W; Núñez-Ramírez, Rafael; Sorzano, Carlos O S; Carazo, José María; Marabini, Roberto

    2009-01-01

    We describe a collection of standardized image processing protocols for electron microscopy single-particle analysis using the XMIPP software package. These protocols allow performing the entire processing workflow starting from digitized micrographs up to the final refinement and evaluation of 3D models. A particular emphasis has been placed on the treatment of structurally heterogeneous data through maximum-likelihood refinements and self-organizing maps as well as the generation of initial 3D models for such data sets through random conical tilt reconstruction methods. All protocols presented have been implemented as stand-alone, executable python scripts, for which a dedicated graphical user interface has been developed. Thereby, they may provide novice users with a convenient tool to quickly obtain useful results with minimum efforts in learning about the details of this comprehensive package. Examples of applications are presented for a negative stain random conical tilt data set on the hexameric helicase G40P and for a structurally heterogeneous data set on 70S Escherichia coli ribosomes embedded in vitrified ice. PMID:18536645

  4. Mixing state of ambient aerosols in Nanjing city by single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; An, Junlin; Shen, Lijuan; Zhu, Bin; Xia, Li; Duan, Qing; Zou, Jianan

    2016-05-01

    To investigate the mixing state and size-resolved aerosol in Nanjing, measurements were carried out for the period 14th January-1st February 2013 by using a Single Particle Aerosol Mass Spectrometer (SPAMS). A total of 10,864,766 particles were sized with vacuum aerodynamic diameter (dva) in the range of 0.2-2.0 μm. Of which, 1,989,725 particles were successfully ionized. Aerosol particles employed for analyzing SPAMS data utilized 96% of the hit particles to identify 5 main particle groups. The particle classes include: K-rich particles (K-CN, K-Nitrate, K-Sulfate and K-Secondary), sodium particles, ammonium particles, carbon-rich particles (OC, EC and OCEC) and heavy-metal particles (Fe-Secondary, Pb-Nitrate, Cu-Mn-Secondary and V-Secondary). EC was the largest contributor with a fraction of 21.78%, followed by K-Secondary (17.87%), K-Nitrate (12.68%) and K-CN (11.25%). High particle level and high RH (relative humidity) are two important factors decreasing visibility in Nanjing. Different particle classes have distinct extinction effects. It anti-correlated well with visibility for the K-secondary, sodium, ammonium, EC, Fe-Secondary and K-Nitrate particles. The proportion of EC particles at 0.65-1.4 μm was up to 25% on haze days and was below 10% on clean days.

  5. Canonical form of three-fermion pure-states with six single particle states

    SciTech Connect

    Chen, Lin; Ž Ðoković, Dragomir; Grassl, Markus; Zeng, Bei

    2014-08-01

    We construct a canonical form for pure states in Λ³(C⁶), the three-fermion system with six single particle states, under local unitary (LU) transformations, i.e., the unitary group U(6). We also construct a minimal set of generators of the algebra of polynomial U(6)-invariants on Λ³(C⁶). It turns out that this algebra is isomorphic to the algebra of polynomial LU-invariants of three-qubits which are additionally invariant under qubit permutations. As a consequence of this surprising fact, we deduce that there is a one-to-one correspondence between the U(6)-orbits of pure three-fermion states in Λ³(C⁶) and the LU orbits of pure three-qubit states when qubit permutations are allowed. As an important byproduct, we obtain a new canonical form for pure three-qubit states under LU transformations U(2) × U(2) × U(2) (no qubit permutations allowed)

  6. Towards a description of particulate fouling: from single particle deposition to clogging.

    PubMed

    Henry, Christophe; Minier, Jean-Pierre; Lefèvre, Grégory

    2012-12-01

    Particulate fouling generally arises from the continuous deposition of colloidal particles on initially clean surfaces, a process which can even lead to a complete blockage of the fluid cross-section. In the present paper, the initial stages of the fouling process (which include single-particle deposition and reentrainment) are first addressed and current modelling state-of-the-art for particle-turbulence and particle-wall interactions is presented. Then, attention is specifically focused on the later stages (which include multilayer formation, clogging and blockage). A detailed review of experimental works brings out the essential mechanisms occurring during these later stages: as for the initial stages, it is found that clogging results from the competition between particle-fluid, particle-surface and particle-particle interactions. Numerical models that have been proposed to reproduce the later stages of fouling are then assessed and a new Lagrangian stochastic approach to clogging in industrial cases is detailed. These models further confirm that, depending on hydrodynamical conditions (the flow velocity), fluid characteristics (such as the ionic strength) as well as particle and substrate properties (such as zeta potentials), particle deposition can lead to the formation of either a single monolayer or multilayers. The present paper outlines also future numerical developments and experimental works that are needed to complete our understanding of the later stages of the fouling process. PMID:23141134

  7. Effect of Wiggler insertions on the single-particle dynamics of the NLC main damping rings

    SciTech Connect

    Venturini, Marco

    2003-07-30

    As they are expected to occupy a large portion of the lattice, wiggler insert ions will introduce significant linear and nonlinear perturbations to the single-particle dynamics in the NLC Main Damping Rings (MDR). The nonlinearities are of particular concern as a sufficiently large Dynamic Aperture (DA) is required for high injection efficiency. The main content of this report is a study of the wigglers impact on the DA of the NLC-MDR latest lattice design. The particle dynamics is modeled by transfer maps calculated by integration through the wiggler fields. For field representation we employed a 3D multipole expansion derived from the field data that were obtained with the aid of a magnet design code. Additional contents of this paper include an investigation of a simplified model of wiggler consisting of a sequence of standard magnet elements (where thin octupoles are used to represent the dominant nonlinearities) and the suggestion of a possible correction scheme to compensate the wiggler nonlinearities.

  8. Inert gases in a terra sample - Measurements in six grain-size fractions and two single particles from Lunar 20.

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Lakatos, S.; Walton, J. R.

    1973-01-01

    Review of the results of inert gas measurements performed on six grain-size fractions and two single particles from four samples of Luna 20 material. Presented and discussed data include the inert gas contents, element and isotope systematics, radiation ages, and Ar-36/Ar-40 systematics.

  9. Synthesis of micro-sized shell-isolated 3D plasmonic superstructures for in situ single-particle SERS monitoring.

    PubMed

    Zhang, Kun; Zhao, Jingjing; Ji, Ji; Liu, Baohong

    2016-04-21

    A single-particle SERS system enabling real-time and in situ observation of Au-catalyzed reactions has been developed. Both the catalytic activity and the SERS effect are coupled into a single bi-functional 3D superstructure comprising Au nanosatellites self-assembled onto a shell-insulated Ag microflower core, which eliminates the interference from photocatalysis. PMID:27044886

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

    NASA Astrophysics Data System (ADS)

    Gu, Yan

    While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. We found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized

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

    NASA Astrophysics Data System (ADS)

    Gu, Yan

    While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. We found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized

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

    SciTech Connect

    Gu, Yan

    2013-01-01

    While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. We found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized

  13. Understanding particle size and distance driven competition of interparticle interactions and effective single-particle anisotropy

    NASA Astrophysics Data System (ADS)

    Pacakova, B.; Mantlikova, A.; Niznansky, D.; Kubickova, S.; Vejpravova, J.

    2016-05-01

    Magnetic response of single-domain nanoparticles (NPs) in concentrated systems is strongly affected by mutual interparticle interactions. However, particle proximity significantly influences single-particle effective anisotropy. To solve which of these two phenomena plays a dominant role in the magnetic response of real NP systems, systematic study on samples with well-defined parameters is required. In our work, we prepared a series of nanocomposites constituted of highly-crystalline and well-isolated CoFe2O4 NPs embedded in an amorphous SiO2 matrix using a single-molecule precursor method. This preparation method enabled us to reach a wide interval of particle size and concentration. We observed that the characteristic parameters of the single-domain state (coercivity, blocking temperature) and dipole–dipole interaction energy ({{E}\\text{d-\\text{d}}} ) scaled with each other and increased with increasing {{≤ft({{d}\\text{XRD}}/r\\right)}3} , where d XRD was the NP diameter and r was the interparticle distance. Our results are in excellent agreement with Monte-Carlo simulations of the particle growth. Moreover, we demonstrated that the contribution of {{E}\\text{d-\\text{d}}} acting as an additional energetic barrier to the superspin reversal or as an average static field did not sufficiently explain how the concentrated NP systems responded to an external magnetic field. Alternations in the blocking temperature and coercivity of our NP systems accounted for reformed relaxations of the NP superspins and modified effective anisotropy energy of the interacting NPs. Therefore, the concept of modified NP effective anisotropy explains the magnetic response of our concentrated NP systems better than the concept of the energy barrier influenced by interparticle interactions.

  14. Development of a Bioaerosol single particle detector (BIO IN) for the Fast Ice Nucleus CHamber FINCH

    NASA Astrophysics Data System (ADS)

    Bundke, U.; Reimann, B.; Nillius, B.; Jaenicke, R.; Bingemer, H.

    2010-02-01

    In this work we present the setup and first tests of our new BIO IN detector. This detector was constructed to classify atmospheric ice nuclei (IN) for their biological content. It is designed to be coupled to the Fast Ice Nucleus CHamber FINCH. If one particle acts as an ice nucleus, it will be at least partly covered with ice at the end of the development section of the FINCH chamber. The device combines an auto-fluorescence detector and a circular depolarization detector for simultaneous detection of biological material and discrimination between water droplets, ice crystals and non activated large aerosol particles. The excitation of biological material with UV light and analysis of auto-fluorescence is a common principle used for flow cytometry, fluorescence microscopy, spectroscopy and imaging. The detection of auto-fluorescence of airborne single particles demands some more experimental effort. However, expensive commercial sensors are available for special purposes, e.g. size distribution measurements. But these sensors will not fit the specifications needed for the FINCH IN counter (e.g. high sample flow of up 10 LPM). The newly developed -low cost- BIO IN sensor uses a single high-power UV LED for the electronic excitation instead of much more expensive UV lasers. Other key advantages of the new sensor are the low weight, compact size, and the little effect on the aerosol sample, which allows it to be coupled with other instruments for further analysis. The instrument will be flown on one of the first missions of the new German research aircraft "HALO" (High Altitude and LOng range).

  15. Seasonal comparisons of single-particle chemical mixing state in Riverside, CA

    NASA Astrophysics Data System (ADS)

    Qin, Xueying; Pratt, Kerri A.; Shields, Laura G.; Toner, Stephen M.; Prather, Kimberly A.

    2012-11-01

    The Study of Organic Aerosols in Riverside, CA (SOAR) field campaign, conducted in the summer and fall of 2005, focused on developing a stronger understanding of seasonal influences on the sources and processes contributing to some of the highest levels of particulate matter in the United States. On-line single-particle mass spectrometry measurements showed that carbonaceous particles generally dominated the submicron size range (>75% by number), compared to primarily aged sea salt and dust in the supermicron size range. During periods with high PM2.5 (particulate matter <2.5 μm) mass and number concentrations, hygroscopic water-containing carbonaceous particles internally mixed with sulfate and nitrate extended up into the supermicron size mode. The mixing state of carbonaceous particles changed with season. In the summer, carbonaceous particles were primarily mixed with secondary (oxidized) organic carbon and sulfate; whereas in the fall, they were mixed mostly with ammonium nitrate. During each season, different processes contributed to the highest pollution levels. In the summer, photochemical production of highly aged secondary organic carbon resulted in daily peaks in both number and mass particle concentrations, followed by removal in the afternoon by the arrival of the clean marine air masses from the coast. In contrast, cooler, more stagnant meteorological conditions in the fall season resulted in the buildup over several days of submicron carbonaceous particles mixed with semivolatile ammonium, nitrate, and amines. In addition, Santa Ana wind events in the fall led to dust and biomass burning particles dominating both the submicron and supermicron size ranges.

  16. Characterization of Silver Nanoparticles Internalized by Arabidopsis Plants Using Single Particle ICP-MS Analysis

    PubMed Central

    Bao, Dongping; Oh, Zhen Guo; Chen, Zhong

    2016-01-01

    Plants act as a crucial interface between humans and their environment. The wide use of nanoparticles (NPs) has raised great concerns about their potential impacts on crop health and food safety, leading to an emerging research theme about the interaction between plants and NPs. However, up to this day even the basic issues concerning the eventual fate and characteristics of NPs after internalization are not clearly delineated due to the lack of a well-established technique for the quantitative analysis of NPs in plant tissues. We endeavored to combine a quantitative approach for NP analysis in plant tissues with TEM to localize the NPs. After using an enzymatic digestion to release the NPs from plant matrices, single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) is employed to determine the size distribution of silver nanoparticles (Ag NPs) in tissues of the model plant Arabidopsis thaliana after exposure to 10 nm Ag NPs. Our results show that Macerozyme R-10 treatment can release Ag NPs from Arabidopsis plants without changing the size of Ag NPs. The characteristics of Ag NPs obtained by SP-ICP-MS in both roots and shoots are in agreement with our transmission electron micrographs, demonstrating that the combination of an enzymatic digestion procedure with SP-ICP-MS is a powerful technique for quantitative determination of NPs in plant tissues. Our data reveal that Ag NPs tend to accumulate predominantly in the apoplast of root tissues whereby a minor portion is transported to shoot tissues. Furthermore, the fact that the measured size distribution of Ag NPs in plant tissue is centered at around 20.70 nm, which is larger than the initial 12.84 nm NP diameter, strongly implies that many internalized Ag NPs do not exist as intact individual particles anymore but are aggregated and/or biotransformed in the plant instead. PMID:26870057

  17. Understanding particle size and distance driven competition of interparticle interactions and effective single-particle anisotropy.

    PubMed

    Pacakova, B; Mantlikova, A; Niznansky, D; Kubickova, S; Vejpravova, J

    2016-05-25

    Magnetic response of single-domain nanoparticles (NPs) in concentrated systems is strongly affected by mutual interparticle interactions. However, particle proximity significantly influences single-particle effective anisotropy. To solve which of these two phenomena plays a dominant role in the magnetic response of real NP systems, systematic study on samples with well-defined parameters is required. In our work, we prepared a series of nanocomposites constituted of highly-crystalline and well-isolated CoFe2O4 NPs embedded in an amorphous SiO2 matrix using a single-molecule precursor method. This preparation method enabled us to reach a wide interval of particle size and concentration. We observed that the characteristic parameters of the single-domain state (coercivity, blocking temperature) and dipole-dipole interaction energy ([Formula: see text]) scaled with each other and increased with increasing [Formula: see text], where d XRD was the NP diameter and r was the interparticle distance. Our results are in excellent agreement with Monte-Carlo simulations of the particle growth. Moreover, we demonstrated that the contribution of [Formula: see text] acting as an additional energetic barrier to the superspin reversal or as an average static field did not sufficiently explain how the concentrated NP systems responded to an external magnetic field. Alternations in the blocking temperature and coercivity of our NP systems accounted for reformed relaxations of the NP superspins and modified effective anisotropy energy of the interacting NPs. Therefore, the concept of modified NP effective anisotropy explains the magnetic response of our concentrated NP systems better than the concept of the energy barrier influenced by interparticle interactions. PMID:27122013

  18. Silver speciation and characterization of nanoparticles released from plastic food containers by single particle ICPMS.

    PubMed

    Ramos, K; Gómez-Gómez, M M; Cámara, C; Ramos, L

    2016-05-01

    Silver migration from a commercial baby feeding bottle and a food box containing AgNPs, as confirmed by SEM-EDX analysis, was evaluated using food simulant solutions [i.e., water, 3% (v/v) acetic acid, and 10% and 90% (v/v) ethanol]. Silver release was investigated at temperatures in the 20-70°C range using contact times of up to 10 days. Migration of silver from the food box was in all cases 2 to 3 orders of magnitude higher than that observed for the baby bottle, although the total silver content in the original box material was half of that found in the baby bottle. As expected, for both food containers, silver migration depended on both the nature of the tested solution and the applied conditions. The highest release was observed for 3% acetic acid at 70°C for 2h, corresponding to 62ngdm(2) and 1887ngdm(-2) of silver for the baby bottle and the food box, respectively. Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) was used to characterise and quantify AgNPs in the food simulants extracts. Sample preparation was optimized to preserve AgNPs integrity. The experimental parameters affecting AgNPs detection, sizing and quantification by SP-ICPMS were also optimised. Analyses of water and acidic extracts revealed the presence of both dissolved silver and AgNPs. Small AgNPs (in the 18-30nm range) and particle number concentrations within the 4-1510 10(6)L(-1) range were detected, corresponding to only 0.1-8.6% of the total silver released from these materials. The only exception was AgNPs migrated into water at 40°C and 70°C from the food box, which accounted for as much as 34% and 69% of the total silver content, respectively. PMID:26946013

  19. Tying Biological Activity to Changes in Sea Spray Aerosol Chemical Composition via Single Particle Analyses

    NASA Astrophysics Data System (ADS)

    Sultana, C. M.; Lee, C.; Collins, D. B.; Axson, J. L.; Laskina, O.; Grandquist, J. R.; Grassian, V. H.; Prather, K. A.

    2014-12-01

    In remote marine environments, sea spray aerosols (SSA) often represent the greatest aerosol burden, thus having significant impacts on direct radiative interactions and cloud processes. Previous studies have shown that SSA is a complex mixture of inorganic salts and an array of dissolved and particulate organic components. Enrichment of SSA organic content is often correlated to seawater chlorophyll concentrations, a measure of oceanic biological activity. As the physical and chemical properties of aerosols control their radiative effects, recent studies conducted by the Center for Aerosol Impacts on Climate and the Environment have endeavored to further elucidate the ties between marine biological activity and primary SSA chemical composition using highly time resolved single particle analyses. A series of experiments performed in the recently developed Marine Aerosol Reference Tank evaluated the effect of changing marine microbial populations on SSA chemical composition, which was monitored via an aerosol time-of-flight mass spectrometer and a variety of offline spectroscopic and microscopic techniques. Each experiment was initiated using unfiltered and untreated seawater, thus maintaining a high level of biogeochemical complexity. This study is the first of its kind to capture daily changes in the primary SSA mixing state over the growth and death of a natural phytoplankton bloom. Increases in organic aerosol types (0.4-3 μm), internally and externally mixed with sea salt, could not be correlated to chlorophyll concentrations. Maximum production of these populations occurred two to four days after the in vivo chlorophyll fluorescence peaked in intensity. This work is in contrast to the current paradigm of correlating SSA organic content to seawater chlorophyll concentration.

  20. Wavelength resolved polarized elastic scatter measurements from micron-sized single particles

    NASA Astrophysics Data System (ADS)

    Sivaprakasam, Vasanthi; Czege, Jozsef; Eversole, Jay D.

    2013-05-01

    The goal of this project is to investigate correlations of polarimetric angular scattering patterns from individual aerosol particles with the particles' physical structure and composition. Such signature patterns may be able to provide particle classification capability, such as, for example, discrimination between man-made and naturally occurring aerosols. If successful, this effort could improve current detection methods for biological warfare (BW) agent aerosols. So far, we have demonstrated an experimental arrangement to measure polarization-state resolved, multi-angle, scattering intensities from single aerosol particles on-the-fly. Our novel approach is a radical departure from conventional polarimetric measurement methods, and a key factor is the use of a multiple-order retarder to prepare different polarization states, depending on the wavelength of the incident light. This novel experimental technique uses a supercontinuum light source, an array of optical fibers, an imaging spectrometer and an EMCCD camera to simultaneously acquire wavelength and angle dependent particle light scattering data as a two-dimensional snapshot. Mueller matrix elements were initially measured from individual particles held in an optical trap (at 405 nm). Since particles can be stably trapped for long periods (hours), we were able to change the optical configuration to acquire multiple Mueller matrix element measurements on a single particle. We have computationally modeled these measurements at specific angles, and the comparison with experimental measurements shows good agreement. Similar measurements have also been made on slowly falling particles, and our current efforts are focused on improving experimental technique sufficiently to make such measurements on flowing particles.

  1. Alignment algorithms and per-particle CTF correction for single particle cryo-electron tomography.

    PubMed

    Galaz-Montoya, Jesús G; Hecksel, Corey W; Baldwin, Philip R; Wang, Eryu; Weaver, Scott C; Schmid, Michael F; Ludtke, Steven J; Chiu, Wah

    2016-06-01

    Single particle cryo-electron tomography (cryoSPT) extracts features from cryo-electron tomograms, followed by 3D classification, alignment and averaging to generate improved 3D density maps of such features. Robust methods to correct for the contrast transfer function (CTF) of the electron microscope are necessary for cryoSPT to reach its resolution potential. Many factors can make CTF correction for cryoSPT challenging, such as lack of eucentricity of the specimen stage, inherent low dose per image, specimen charging, beam-induced specimen motions, and defocus gradients resulting both from specimen tilting and from unpredictable ice thickness variations. Current CTF correction methods for cryoET make at least one of the following assumptions: that the defocus at the center of the image is the same across the images of a tiltseries, that the particles all lie at the same Z-height in the embedding ice, and/or that the specimen, the cryo-electron microscopy (cryoEM) grid and/or the carbon support are flat. These experimental conditions are not always met. We have developed a CTF correction algorithm for cryoSPT without making any of the aforementioned assumptions. We also introduce speed and accuracy improvements and a higher degree of automation to the subtomogram averaging algorithms available in EMAN2. Using motion-corrected images of isolated virus particles as a benchmark specimen, recorded with a DE20 direct detection camera, we show that our CTF correction and subtomogram alignment routines can yield subtomogram averages close to 4/5 Nyquist frequency of the detector under our experimental conditions. PMID:27016284

  2. Chemical compositions of subway particles in Seoul, Korea determined by a quantitative single particle analysis.

    PubMed

    Kang, Sunni; Hwang, HeeJin; Park, YooMyung; Kim, HyeKyoung; Ro, Chul-Un

    2008-12-15

    A novel single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal subway samples collected at a subway station in Seoul, Korea. For all 8 samples collected twice in each season, 4 major types of subway particles, based on their chemical compositions, are significantly encountered: Fe-containing; soil-derived; carbonaceous; and secondary nitrate and/or sulfate particles. Fe-containing particles are generated indoors from wear processes at rail-wheel-brake interfaces while the others may be introduced mostly from the outdoor urban atmosphere. Fe-containing particles are the most frequently encountered with relative abundances in the range of 61-79%. In this study, it is shown that Fe-containing subway particles almost always exist either as partially or fully oxidized forms in underground subway microenvironments. Their relative abundances of Fe-containing particles increase as particle sizes decrease. Relative abundances of Fe-containing particles are higher in morning samples than in afternoon samples because of heavier train traffic in the morning. In the summertime samples, Fe-containing particles are the most abundantly encountered, whereas soil-derived and nitrate/sulfate particles are the least encountered, indicating the air-exchange between indoor and outdoor environments is limited in the summer, owing to the air-conditioning in the subway system. In our work, it was observed that the relative abundances of the particles of outdoor origin vary somewhat among seasonal samples to a lesser degree, reflecting that indoor emission sources predominate. PMID:19174870

  3. A Bayesian approach for suppression of limited angular sampling artifacts in single particle 3D reconstruction.

    PubMed

    Moriya, Toshio; Acar, Erman; Cheng, R Holland; Ruotsalainen, Ulla

    2015-09-01

    In the single particle reconstruction, the initial 3D structure often suffers from the limited angular sampling artifact. Selecting 2D class averages of particle images generally improves the accuracy and efficiency of the reference-free 3D angle estimation, but causes an insufficient angular sampling to fill the information of the target object in the 3D frequency space. Similarly, the initial 3D structure by the random-conical tilt reconstruction has the well-known "missing cone" artifact. Here, we attempted to solve the limited angular sampling problem by sequentially applying maximum a posteriori estimate with expectation maximization algorithm (sMAP-EM). Using both simulated and experimental cryo-electron microscope images, the sMAP-EM was compared to the direct Fourier method on the basis of reconstruction error and resolution. To establish selection criteria of the final regularization weight for the sMAP-EM, the effects of noise level and sampling sparseness on the reconstructions were examined with evenly distributed sampling simulations. The frequency information filled in the missing cone of the conical tilt sampling simulations was assessed by developing new quantitative measurements. All the results of visual and numerical evaluations showed the sMAP-EM performed better than the direct Fourier method, regardless of the sampling method, noise level, and sampling sparseness. Furthermore, the frequency domain analysis demonstrated that the sMAP-EM can fill the meaningful information in the unmeasured angular space without detailed a priori knowledge of the objects. The current research demonstrated that the sMAP-EM has a high potential to facilitate the determination of 3D protein structures at near atomic-resolution. PMID:26193484

  4. Oscillations of a spring-magnet system damped by a conductive plate

    NASA Astrophysics Data System (ADS)

    Ladera, C. L.; Donoso, G.

    2013-09-01

    We study the motion of a spring-magnet system that oscillates with very low frequencies above a circular horizontal non-magnetizable conductive plate. The magnet oscillations couple with the plate via the Foucault currents induced therein. We develop a simple theoretical model for this magneto-mechanical oscillator, a model that leads to the equation of a damped harmonic oscillator, whose weak attenuation constant depends upon the system parameters, e.g. the electrical conductivity of the constituent material of the plate and its thickness. We present a set of validating experiments, the results of which are predicted with good accuracy by our analytical model. Additional experiments can be performed with this oscillating system or its variants. This oscillator is simple and low-cost, easy to assemble, and can be used in experiments or project works in physics teaching laboratories at the undergraduate level.

  5. Neurodynamic oscillators

    NASA Technical Reports Server (NTRS)

    Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz

    1995-01-01

    Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

  6. Power Matters: Foucault's "Pouvoir/Savoir" as a Conceptual Lens in Information Research and Practice

    ERIC Educational Resources Information Center

    Olsson, Michael; Heizmann, Helena

    2015-01-01

    Introduction: This paper advocates Foucault's notion of pouvoir/savoir (power/knowledge) as a conceptual lens that information researchers might fruitfully use to develop a richer understanding of the relationship between knowledge and power. Methods: Three of the authors' earlier studies are employed to illustrate the use of this conceptual lens.…

  7. Criticising with Foucault: Towards a Guiding Framework for Socio-Political Studies in Mathematics Education

    ERIC Educational Resources Information Center

    Kollosche, David

    2016-01-01

    Socio-political studies in mathematics education often touch complex fields of interaction between education, mathematics and the political. In this paper I present a Foucault-based framework for socio-political studies in mathematics education which may guide research in that area. In order to show the potential of such a framework, I discuss the…

  8. Marx and Foucault: Subjectivity, Employability and the Crisis of Youth Unemployment in the Great Global Recession

    ERIC Educational Resources Information Center

    Peters, Michael A.; Besley, Tina

    2013-01-01

    This article explores the different approaches taken to the concepts of work or labour by Marx and Foucault, examining in particular the question of subjectivity in relation to youth unemployment and the current crisis of youth unemployment as part of the aftermath of the global recession of 2008.

  9. Michel Foucault Goes Outside: Discipline and Control in the Practice of Outdoor Education

    ERIC Educational Resources Information Center

    Bowdridge, Michael; Blenkinsop, Sean

    2011-01-01

    This paper is concerned with if, and how, measures of discipline and control are involved in outdoor and experiential education. Using the work of the French philosopher Michel Foucault, author of Discipline and Punish (1975), we shall explore how educational practice may be used to control people and to render them into "docile bodies." We follow…

  10. Positivism, Foucault, and the Fantasia of the Library: Conceptions of Knowledge and the Modern Library Experience.

    ERIC Educational Resources Information Center

    Radford, Gary P.

    1992-01-01

    Discusses theoretical conceptions of the library and suggests that modern conceptions are informed by a view of knowledge grounded in early twentieth-century positivism. The view of scientific knowledge developed by Michael Foucault is described, and possibilities for the creation of new knowledge are considered. (75 references) (LRW)

  11. Reference Two. Does Foucault Kill Derrida in the Game of References? The Example of Master's Dissertations.

    ERIC Educational Resources Information Center

    Smith, Howard A.

    1999-01-01

    Discusses a selection of ideas and writings by Michael Foucault into competition with those of Jacques Derrida. Consisted of a single game of references for which the references were those cited in a sample of master's theses produced recently at Queen's University. Examined master's dissertations, because these are the usual means by which…

  12. Braverman, Foucault and the Labor Process: Framing the Current High-Skills Debate

    ERIC Educational Resources Information Center

    Lewis, Theodore

    2007-01-01

    This article examines the current high-skills discourse against the backdrop of labor process theory. It draws on the theoretical debate between Harry Braverman and Michael Foucault, supplementing the traditional treatment of the labor process with Foucauldian insights. The primary argument is that especially in the market-led economies, current…

  13. Foucault's "fearless speech" and the transformation and mentoring of medical students

    PubMed Central

    Papadimos, Thomas J; Murray, Stuart J

    2008-01-01

    In his six 1983 lectures published under the title, Fearless Speech (2001), Michel Foucault developed the theme of free speech and its relation to frankness, truth-telling, criticism, and duty. Derived from the ancient Greek word parrhesia, Foucault's analysis of free speech is relevant to the mentoring of medical students. This is especially true given the educational and social need to transform future physicians into able citizens who practice a fearless freedom of expression on behalf of their patients, the public, the medical profession, and themselves in the public and political arena. In this paper, we argue that Foucault's understanding of free speech, or parrhesia, should be read as an ethical response to the American Medical Association's recent educational effort, Initiative to Transform Medical Education (ITME): Recommendations for change in the system of medical education (2007). In this document, the American Medical Association identifies gaps in medical education, emphasizing the need to enhance health system safety and quality, to improve education in training institutions, and to address the inadequacy of physician preparedness in new content areas. These gaps, and their relationship to the ITME goal of promoting excellence in patient care by implementing reform in the US system of medical education, call for a serious consideration and use of Foucault's parrhesia in the way that medical students are trained and mentored. PMID:18419809

  14. Autonomy, Candour and Professional Teacher Practice: A Discussion Inspired by the Later Works of Michel Foucault

    ERIC Educational Resources Information Center

    Raaen, Finn Daniel

    2011-01-01

    Autonomy is considered to be an important feature of professionals and to provide a necessary basis for their informed judgments. In this article these notions will be challenged. In this article I use Michel Foucault's deconstruction of the idea of the autonomous citizen, and his later attempts to reconstruct that idea, in order to bring some new…

  15. Foucault's "fearless speech" and the transformation and mentoring of medical students.

    PubMed

    Papadimos, Thomas J; Murray, Stuart J

    2008-01-01

    In his six 1983 lectures published under the title, Fearless Speech (2001), Michel Foucault developed the theme of free speech and its relation to frankness, truth-telling, criticism, and duty. Derived from the ancient Greek word parrhesia, Foucault's analysis of free speech is relevant to the mentoring of medical students. This is especially true given the educational and social need to transform future physicians into able citizens who practice a fearless freedom of expression on behalf of their patients, the public, the medical profession, and themselves in the public and political arena. In this paper, we argue that Foucault's understanding of free speech, or parrhesia, should be read as an ethical response to the American Medical Association's recent educational effort, Initiative to Transform Medical Education (ITME): Recommendations for change in the system of medical education (2007). In this document, the American Medical Association identifies gaps in medical education, emphasizing the need to enhance health system safety and quality, to improve education in training institutions, and to address the inadequacy of physician preparedness in new content areas. These gaps, and their relationship to the ITME goal of promoting excellence in patient care by implementing reform in the US system of medical education, call for a serious consideration and use of Foucault's parrhesia in the way that medical students are trained and mentored. PMID:18419809

  16. Making Use of Foucault in a Study of Specific Parrhesiastic Scholars

    ERIC Educational Resources Information Center

    Huckaby, M. Francyne

    2008-01-01

    In this article, I describe how I made use of Foucault theoretically and methodologically in a study of five specific parrhesiastic scholars. Such scholars challenge hegemony in educational policies and practices, and advocate for educational reform and societal structures that move toward equity instead of marginalization. The article begins by…

  17. Derrida, Foucault and Critical Pedagogies of Friendship in Conflict-Troubled Societies

    ERIC Educational Resources Information Center

    Zembylas, Michalinos

    2015-01-01

    The aim of this paper is to place Derrida's and Foucault's ideas on friendship in conversation and then discuss how those ideas provide a pedagogical space in which critical educators in conflict-troubled societies can promote new modes of being and living with others. In particular, the notion of critical pedagogies of friendship is…

  18. Quantitative phase tomography by using x-ray microscope with Foucault knife-edge scanning filter

    NASA Astrophysics Data System (ADS)

    Watanabe, Norio; Tsuburaya, Yuji; Shimada, Akihiro; Aoki, Sadao

    2016-01-01

    Quantitative phase tomography was evaluated by using a differential phase microscope with a Foucault knife-edge scanning filter. A 3D x-ray phase image of polystyrene beads was obtained at 5.4 keV. The reconstructed refractive index was fairly good agreement with the Henke's tabulated data.

  19. Implementation of a quantitative Foucault knife-edge method by means of isophotometry

    NASA Astrophysics Data System (ADS)

    Zhevlakov, A. P.; Zatsepina, M. E.; Kirillovskii, V. K.

    2014-06-01

    Detailed description of stages of computer processing of the shadowgrams during implementation of a modern quantitative Foucault knife-edge method is presented. The map of wave-front aberrations introduced by errors of an optical surface or a system, along with the results of calculation of the set of required characteristics of image quality, are shown.

  20. Human Science for Human Freedom? Piaget's Developmental Research and Foucault's Ethical Truth Games

    ERIC Educational Resources Information Center

    Zhao, Guoping

    2012-01-01

    The construction of the modern subject and the pursuit of human freedom and autonomy, as well as the practice of human science has been pivotal in the development of modern education. But for Foucault, the subject is only the effect of discourses and power-knowledge arrangements, and modern human science is part of the very arrangement that has…

  1. Foucault and the Use of Critique: Breaching the Self-Evidence of Educational Practices

    ERIC Educational Resources Information Center

    Bye, Jayne

    2015-01-01

    This paper poses methodological questions about the role and limits of Foucault's concept of governmentality in education research. Firstly, it argues for the utility of governmentality as a means of exploring questions of power regardless of domain or scale. Secondly, it explores the boundary between the tasks of formulating critique and…

  2. Foucault and the Architecture of Surveillance: Creating Regimes of Power in Schools, Shrines, and Society

    ERIC Educational Resources Information Center

    Piro, Joseph M.

    2008-01-01

    Michel Foucault's critical studies concerning regimes of power are of special interest when applied to architecture. In particular, he warned of the hazards of building surveillance into architectural structures for the purpose of monitoring people and took as his historical exemplar English philosopher Jeremy Bentham's "Panopticon," a structure…

  3. Power/Knowledge for Educational Theory: Stephen Ball and the Reception of Foucault

    ERIC Educational Resources Information Center

    Wang, Chia-Ling

    2011-01-01

    This paper explores the significance of the concept of power/knowledge in educational theory. The argument proceeds in two main parts. In the first, I consider aspects of Stephen J. Ball's highly influential work in educational theory. I examine his reception of Foucault's concept of power/knowledge and suggest that there are problems in his…

  4. Galactic oscillations

    NASA Technical Reports Server (NTRS)

    Miller, R. H.

    1991-01-01

    Long-lived oscillations that act like normal modes are described. The total kinetic energy is found to vary with time by amounts far in excess of the fluctuations expected from the virial theorem, and the variation shows periodic patterns that suggest oscillations. Experimental results indicate that oscillation amplitudes depend on the nature of the model. It is noted that it is difficult to answer questions about likely amplitudes in real galaxies with any confidence at the present time.

  5. Radiation damage in single-particle cryo-electron microscopy: effects of dose and dose rate.

    PubMed

    Karuppasamy, Manikandan; Karimi Nejadasl, Fatemeh; Vulovic, Milos; Koster, Abraham J; Ravelli, Raimond B G

    2011-05-01

    an improved understanding of the effects of dose and dose rate will aid single-particle cryo-electron microscopists to have better control of the outcome of their experiments. PMID:21525648

  6. Radiation damage in single-particle cryo-electron microscopy: effects of dose and dose rate

    PubMed Central

    Karuppasamy, Manikandan; Karimi Nejadasl, Fatemeh; Vulovic, Milos; Koster, Abraham J.; Ravelli, Raimond B. G.

    2011-01-01

    combined with an improved understanding of the effects of dose and dose rate will aid single-particle cryo-electron microscopists to have better control of the outcome of their experiments. PMID:21525648

  7. Nanoparticle size detection limits by single particle ICP-MS for 40 elements.

    PubMed

    Lee, Sungyun; Bi, Xiangyu; Reed, Robert B; Ranville, James F; Herckes, Pierre; Westerhoff, Paul

    2014-09-01

    The quantification and characterization of natural, engineered, and incidental nano- to micro-size particles are beneficial to assessing a nanomaterial's performance in manufacturing, their fate and transport in the environment, and their potential risk to human health. Single particle inductively coupled plasma mass spectrometry (spICP-MS) can sensitively quantify the amount and size distribution of metallic nanoparticles suspended in aqueous matrices. To accurately obtain the nanoparticle size distribution, it is critical to have knowledge of the size detection limit (denoted as Dmin) using spICP-MS for a wide range of elements (other than a few available assessed ones) that have been or will be synthesized into engineered nanoparticles. Herein is described a method to estimate the size detection limit using spICP-MS and then apply it to nanoparticles composed of 40 different elements. The calculated Dmin values correspond well for a few of the elements with their detectable sizes that are available in the literature. Assuming each nanoparticle sample is composed of one element, Dmin values vary substantially among the 40 elements: Ta, U, Ir, Rh, Th, Ce, and Hf showed the lowest Dmin values, ≤10 nm; Bi, W, In, Pb, Pt, Ag, Au, Tl, Pd, Y, Ru, Cd, and Sb had Dmin in the range of 11-20 nm; Dmin values of Co, Sr, Sn, Zr, Ba, Te, Mo, Ni, V, Cu, Cr, Mg, Zn, Fe, Al, Li, and Ti were located at 21-80 nm; and Se, Ca, and Si showed high Dmin values, greater than 200 nm. A range of parameters that influence the Dmin, such as instrument sensitivity, nanoparticle density, and background noise, is demonstrated. It is observed that, when the background noise is low, the instrument sensitivity and nanoparticle density dominate the Dmin significantly. Approaches for reducing the Dmin, e.g., collision cell technology (CCT) and analyte isotope selection, are also discussed. To validate the Dmin estimation approach, size distributions for three engineered nanoparticle samples were

  8. Calcium Oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlying mechanism of calcium oscillations through the power of mathematical modeling. We also summarize recent findings on the role of calcium entry through store-operated channels in sustaining calcium oscillations and in the mechanism by which calcium oscillations couple to downstream effectors. PMID:21421924

  9. [Application of on-line single particle aerosol mass spectrometry (SPAMS) for studying major components in fine particulate matter].

    PubMed

    Fu, Huai-yu; Yan, Cai-qing; Zheng, Mei; Cai, Jing; Li, Xiao-ying; Zhang, Yan-jun; Zhou Zhen; Fu, Zhong; Li, Mei; Li, Lei; Zhang, Yuan-Hang

    2014-11-01

    Based on preliminary studies by aerosol time-of-flight mass spectrometer (ATOFMS) and single particle aerosol mass spectrometer (SPAMS), typical methods for identifying the number of particles (or particle count) for five major components including sulfate, nitrate, ammonium, organic carbon (OC), and elemental carbon (EC) in China and abroad were summarized. In this study, combined with the characteristics of single particle mass spectrum by SPAMS, an optimized method is proposed. With field measurement using SPAMS during January 2013 in Beijing, particle counts of sulfate, nitrate, ammonium, OC, and EC determined by different methods were compared. The comparison with results of off-line filter analyses for these five components proved that the method proposed in this study is comparable and optimized. We also suggest factors needed to be considered in future application of SPAMS and other areas that require in-depth research. PMID:25639078

  10. Continuous changes in structure mapped by manifold embedding of single-particle data in cryo-EM.

    PubMed

    Frank, Joachim; Ourmazd, Abbas

    2016-05-01

    Cryo-electron microscopy, when combined with single-particle reconstruction, is a powerful method for studying macromolecular structure. Recent developments in detector technology have pushed the resolution into a range comparable to that of X-ray crystallography. However, cryo-EM is able to separate and thus recover the structure of each of several discrete structures present in the sample. For the more general case involving continuous structural changes, a novel technique employing manifold embedding has been recently demonstrated. Potentially, the entire work-cycle of a molecular machine may be observed as it passes through a continuum of states, and its free-energy landscape may be mapped out. This technique will be outlined and discussed in the context of its application to a large single-particle dataset of yeast ribosomes. PMID:26884261

  11. Synthesis of micro-sized shell-isolated 3D plasmonic superstructures for in situ single-particle SERS monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Zhao, Jingjing; Ji, Ji; Liu, Baohong

    2016-04-01

    A single-particle SERS system enabling real-time and in situ observation of Au-catalyzed reactions has been developed. Both the catalytic activity and the SERS effect are coupled into a single bi-functional 3D superstructure comprising Au nanosatellites self-assembled onto a shell-insulated Ag microflower core, which eliminates the interference from photocatalysis.A single-particle SERS system enabling real-time and in situ observation of Au-catalyzed reactions has been developed. Both the catalytic activity and the SERS effect are coupled into a single bi-functional 3D superstructure comprising Au nanosatellites self-assembled onto a shell-insulated Ag microflower core, which eliminates the interference from photocatalysis. Electronic supplementary information (ESI) available: Details of the synthesis and characterization of the Ag@SiO2@Au superstructures (SEM and TEM images, UV/vis and SERS spectra). See DOI: 10.1039/c6nr00278a

  12. The non-destructive identification of solid over-the-counter medications using single particle aerosol mass spectrometry.

    PubMed

    Martin, Audrey N; Farquar, George R; Jones, A Daniel; Frank, Matthias

    2007-01-01

    Single over-the-counter medication tablets were analyzed in real time using Single Particle Aerosol Mass Spectrometry (SPAMS). Dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles dislodged from a single tablet without destroying the shape or markings of each tablet. The solid tablet was placed in a modified-top glass vial and shaken to dislodge and introduce micrometer-sized particles into the SPAMS system. Unique spectra from these particles were obtained in less than 1 s for single tablets of aspirin, ibuprofen, pseudoephedrine, phenylephrine, loratadine, or diphenhydramine. The signals obtained allowed the non-destructive identification of an individual tablet in seconds. SPAMS presents an ideal system for high-throughput analysis of solid drugs. PMID:17935106

  13. Importance of the single-particle continuum in BCS pairing with a pseudostate basis

    NASA Astrophysics Data System (ADS)

    Lay, J. A.; Alonso, C. E.; Fortunato, L.; Vitturi, A.

    2016-05-01

    In a recent work [arXiv:1510.03185] the use of the Transformed Harmonic Oscillator (THO) basis for the discretization of the singleparticle continuum into a Generalized Bardeen-Cooper-Schrieffer (BCS) formalism was proposed for the description of weakly bound nuclei. We make use of the flexibility of this formalism to study the evolution of the pairing when the nucleus becomes more and more weakly bound. Specifically we focus on the evolution of the occupation of the different partial waves in 22O when the Fermi level approaches zero.

  14. A Method for Oscillation Errors Restriction of SINS Based on Forecasted Time Series

    PubMed Central

    Zhao, Lin; Li, Jiushun; Cheng, Jianhua; Jia, Chun; Wang, Qiufan

    2015-01-01

    Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of SINS based on forecasted time series is proposed by analyzing the characteristics of periodic oscillation errors. The innovative method gains multiple sets of navigation solutions with different phase delays in virtue of the forecasted time series acquired through the measurement data of the inertial measurement unit (IMU). With the help of curve-fitting based on least square method, the forecasted time series is obtained while distinguishing and removing small angular motion interference in the process of initial alignment. Finally, the periodic oscillation errors are restricted on account of the principle of eliminating the periodic oscillation signal with a half-wave delay by mean value. Simulation and test results show that the method has good performance in restricting the Schuler, Foucault, and Earth oscillation errors of SINS. PMID:26193283

  15. A Method for Oscillation Errors Restriction of SINS Based on Forecasted Time Series.

    PubMed

    Zhao, Lin; Li, Jiushun; Cheng, Jianhua; Jia, Chun; Wang, Qiufan

    2015-01-01

    Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of SINS based on forecasted time series is proposed by analyzing the characteristics of periodic oscillation errors. The innovative method gains multiple sets of navigation solutions with different phase delays in virtue of the forecasted time series acquired through the measurement data of the inertial measurement unit (IMU). With the help of curve-fitting based on least square method, the forecasted time series is obtained while distinguishing and removing small angular motion interference in the process of initial alignment. Finally, the periodic oscillation errors are restricted on account of the principle of eliminating the periodic oscillation signal with a half-wave delay by mean value. Simulation and test results show that the method has good performance in restricting the Schuler, Foucault, and Earth oscillation errors of SINS. PMID:26193283

  16. Many-Body Localization and Quantum Nonergodicity in a Model with a Single-Particle Mobility Edge

    NASA Astrophysics Data System (ADS)

    Li, Xiaopeng; Ganeshan, Sriram; Pixley, J. H.

    We investigate many-body localization in the presence of a single-particle mobility edge. By considering an interacting deterministic model with an incommensurate potential in one dimension we find that the single-particle mobility edge in the noninteracting system leads to a many-body mobility edge in the corresponding interacting system for certain parameter regimes. Using exact diagonalization, we probe the mobility edge via energy resolved entanglement entropy (EE) and study the energy resolved applicability (or failure) of the eigenstate thermalization hypothesis (ETH). Our numerical results indicate that the transition separating area and volume law scaling of the EE does not coincide with the nonthermal to thermal transition. Consequently, there exists an extended nonergodic phase for an intermediate energy window where the many-body eigenstates violate the ETH while manifesting volume law EE scaling. We also establish that the model possesses an infinite temperature many-body localization transition despite the existence of a single-particle mobility edge. We propose a practical scheme to test our predictions in atomic optical lattice experiments which can directly probe the effects of the mobility edge. JQI-NSF-PFC, AROAtomtronics- MURI, and LPS-CMTC, UMD supercomputing resources.

  17. Many-Body Localization and Quantum Nonergodicity in a Model with a Single-Particle Mobility Edge

    NASA Astrophysics Data System (ADS)

    Li, Xiaopeng; Ganeshan, Sriram; Pixley, J. H.; Das Sarma, S.

    2015-10-01

    We investigate many-body localization in the presence of a single-particle mobility edge. By considering an interacting deterministic model with an incommensurate potential in one dimension we find that the single-particle mobility edge in the noninteracting system leads to a many-body mobility edge in the corresponding interacting system for certain parameter regimes. Using exact diagonalization, we probe the mobility edge via energy resolved entanglement entropy (EE) and study the energy resolved applicability (or failure) of the eigenstate thermalization hypothesis (ETH). Our numerical results indicate that the transition separating area and volume law scaling of the EE does not coincide with the nonthermal to thermal transition. Consequently, there exists an extended nonergodic phase for an intermediate energy window where the many-body eigenstates violate the ETH while manifesting volume law EE scaling. We also establish that the model possesses an infinite temperature many-body localization transition despite the existence of a single-particle mobility edge. We propose a practical scheme to test our predictions in atomic optical lattice experiments which can directly probe the effects of the mobility edge.

  18. Dynamics of nuclear single-particle structure in covariant theory of particle-vibration coupling: From light to superheavy nuclei

    SciTech Connect

    Litvinova, E. V.; Afanasjev, A. V.

    2011-07-15

    The impact of particle-vibration coupling and polarization effects due to deformation and time-odd mean fields on single-particle spectra is studied systematically in doubly magic nuclei from low-mass {sup 56}Ni up to superheavy ones. Particle-vibration coupling is treated fully self-consistently within the framework of the relativistic particle-vibration coupling model. Polarization effects due to deformation and time-odd mean field induced by odd particle are computed within covariant density functional theory. It has been found that among these contributions the coupling to vibrations makes a major impact on the single-particle structure. The impact of particle-vibration coupling and polarization effects on calculated single-particle spectra, the size of the shell gaps, the spin-orbit splittings and the energy splittings in pseudospin doublets is discussed in detail; these physical observables are compared with experiment. Particle-vibration coupling has to be taken into account when model calculations are compared with experiment since this coupling is responsible for observed fragmentation of experimental levels; experimental spectroscopic factors are reasonably well described in model calculations.

  19. Facilitating model reconstruction for single-particle scattering using small-angle X-ray scattering methods1

    PubMed Central

    Ma, Shufen; Liu, Haiguang

    2016-01-01

    X-ray free-electron lasers generate intense femtosecond X-ray pulses, so that high-resolution structure determination becomes feasible from noncrystalline samples, such as single particles or single molecules. At the moment, the orientation of sample particles cannot be precisely controlled, and consequently the unknown orientation needs to be recovered using computational algorithms. This delays the model reconstruction until all the scattering patterns have been re-oriented, which often entails a long elapse of time and until the completion of the experiment. The scattering patterns from single particles or multiple particles can be summed to form a virtual powder diffraction pattern, and the low-resolution region, corresponding to the small-angle X-ray scattering (SAXS) regime, can be analysed using existing SAXS methods. This work presents a pipeline that converts single-particle data sets into SAXS data, from which real-time model reconstruction is achieved using the model retrieval approach implemented in the software package SASTBX [Liu, Hexemer & Zwart (2012). J. Appl. Cryst.45, 587–593]. To illustrate the applications, two case studies are presented with real experimental data sets collected at the Linac Coherent Light Source. PMID:27047310

  20. Bloch-Landau-Zener dynamics in single-particle Wannier-Zeeman systems

    NASA Astrophysics Data System (ADS)

    Ke, Yongguan; Qin, Xizhou; Zhong, Honghua; Huang, Jiahao; He, Chunshan; Lee, Chaohong

    2015-05-01

    Stimulated by the experimental realization of spin-dependent tunneling via a gradient magnetic field [C. J. Kennedy et al., Phys. Rev. Lett. 111, 225301 (2013);, 10.1103/PhysRevLett.111.225301 M. Aidelsburger et al., Phys. Rev. Lett. 111, 185301 (2013), 10.1103/PhysRevLett.111.185301], we investigate the dynamics of Bloch oscillations and Landau-Zener tunneling of single spin-half particles in a periodic potential under the influence of a spin-dependent constant force. In analogy to the Wannier-Stark system, we call our system the Wannier-Zeeman system. If there is no coupling between the two spin states, the system can be described by two crossing Wannier-Stark ladders with opposite tilts. The spatial crossing between two Wannier-Stark ladders becomes a spatial anticrossing if the two spin states are coupled by external fields. For a wave packet away from the spatial anticrossing, due to the spin-dependent constant force, it will undergo spatial Landau-Zener transitions assisted by the intrinsic intraband Bloch oscillations, which we call the Bloch-Landau-Zener dynamics. If the interspin coupling is sufficiently strong, the system undergoes adiabatic Bloch-Landau-Zener dynamics, in which the spin dynamics follows the local dressed states. Otherwise, for nonstrong interspin couplings, the system undergoes nonadiabatic Bloch-Landau-Zener dynamics.

  1. Enrichment of Mineral Dust Storm Particles with Sea Salt Elements - Using bulk and Single Particle Analyses

    NASA Astrophysics Data System (ADS)

    Mamane, Y.; Perrino, C.; Yossef, O.

    2009-12-01

    Mineral aerosol emitted from African and Asian deserts plays an important role in the atmosphere. During their long-range transport, the physical and chemical properties of mineral dust particles change due to heterogeneous reactions with trace gases, coagulation with other particles, and in-cloud processing. These processes affect the optical and hygroscopic properties of dust particles, and in general influencing the physics and chemistry of the atmosphere. Four African and Arabian dust storm episodes affecting the East Mediterranean Coast in the spring of 2006 have been characterized, to determine if atmospheric natural dust particles are enriched with sea salt and anthropogenic pollution. Particle samplers included PM10 and manual dichotomous sampler that collected fine and coarse particles. Three sets of filters were used: Teflon filters for gravimetric, elemental and ionic analyses; Pre-fired Quartz-fiber filters for elemental and organic carbon; and Nuclepore filters for scanning electron microscopy analysis. Computer-controlled scanning electron microscopy (Philips XL 30 ESEM) was used to analyze single particle, for morphology, size and chemistry of selected filter samples. A detailed chemical and microscopical characterization has been performed for the particles collected during dust event days and during clear days. The Saharan and Arabian air masses increased significantly the daily mass concentrations of the coarse and the fine particle fractions. Carbonates, mostly as soil calcites mixed with dolomites, and silicates are the major components of the coarse fraction, followed by sea salt particles. In addition, the levels of anthropogenic heavy metals and sea salt elements registered during the dust episode were considerably higher than levels recorded during clear days. Sea salt elements contain Na and Cl, and smaller amounts of Mg, K, S and Br. Cl ranges from 300 to 5500 ng/m3 and Na from 100 to almost 2400 ng/m3. The Cl to Na ratio on dusty days in

  2. The development of optical microscopy techniques for the advancement of single-particle studies

    NASA Astrophysics Data System (ADS)

    Marchuk, Kyle

    Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called "non-blinking" quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

  3. Determination of single particle mass spectral signatures from light-duty vehicle emissions.

    PubMed

    Sodeman, David A; Toner, Stephen M; Prather, Kimberly A

    2005-06-15

    In this study, 28 light-duty gasoline vehicles (LDV) were operated on a chassis dynamometer at the California Air Resources Board Haagen-Smit Facility in El Monte, CA. The mass spectra of individual particles emitted from these vehicles were measured using aerosol time-of-flight mass spectrometry (ATOFMS). A primary goal of this study involves determining representative size-resolved single particle mass spectral signatures that can be used in future ambient particulate matter source apportionment studies. Different cycles were used to simulate urban driving conditions including the federal testing procedure (FTP), unified cycle (UC), and the correction cycle (CC). The vehicles were selected to span a range of catalytic converter (three-way, oxidation, and no catalysts) and engine technologies (vehicles models from 1953 to 2003). Exhaust particles were sampled directly from a dilution and residence chamber system using particle sizing instruments and an ATOFMS equipped with an aerodynamic lens (UF-ATOFMS) analyzing particles between 50 and 300 nm. On the basis of chemical composition, 10 unique chemical types describe the majority of the particles with distinct size and temporal characteristics. In the ultrafine size range (between 50 and 100 nm), three elemental carbon (EC) particle types dominated, all showing distinct EC signatures combined with Ca, phosphate, sulfate, and a lower abundance of organic carbon (OC). The relative fraction of EC particle types decreased as particle size increased with OC particles becoming more prevalent above 100 nm. Depending on the vehicle and cycle, several distinct OC particle types produced distinct ion patterns, including substituted aromatic compounds and polycyclic aromatic hydrocarbons (PAH), coupled with other chemical species including ammonium, EC, nitrate, sulfate, phosphate, V, and Ca. The most likely source of the Ca and phosphate in the particles is attributed to the lubricating oil. Significant variability was

  4. Developing new optical imaging techniques for single particle and molecule tracking in live cells

    SciTech Connect

    Sun, Wei

    2010-01-01

    Differential interference contrast (DIC) microscopy is a far-field as well as wide-field optical imaging technique. Since it is non-invasive and requires no sample staining, DIC microscopy is suitable for tracking the motion of target molecules in live cells without interfering their functions. In addition, high numerical aperture objectives and condensers can be used in DIC microscopy. The depth of focus of DIC is shallow, which gives DIC much better optical sectioning ability than those of phase contrast and dark field microscopies. In this work, DIC was utilized to study dynamic biological processes including endocytosis and intracellular transport in live cells. The suitability of DIC microscopy for single particle tracking in live cells was first demonstrated by using DIC to monitor the entire endocytosis process of one mesoporous silica nanoparticle (MSN) into a live mammalian cell. By taking advantage of the optical sectioning ability of DIC, we recorded the depth profile of the MSN during the endocytosis process. The shape change around the nanoparticle due to the formation of a vesicle was also captured. DIC microscopy was further modified that the sample can be illuminated and imaged at two wavelengths simultaneously. By using the new technique, noble metal nanoparticles with different shapes and sizes were selectively imaged. Among all the examined metal nanoparticles, gold nanoparticles in rod shapes were found to be especially useful. Due to their anisotropic optical properties, gold nanorods showed as diffraction-limited spots with disproportionate bright and dark parts that are strongly dependent on their orientation in the 3D space. Gold nanorods were developed as orientation nanoprobes and were successfully used to report the self-rotation of gliding microtubules on kinesin coated substrates. Gold nanorods were further used to study the rotational motions of cargoes during the endocytosis and intracellular transport processes in live mammalian

  5. The development of optical microscopy techniques for the advancement of single-particle studies

    SciTech Connect

    Marchuk, Kyle

    2013-05-15

    Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called “non-blinking” quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

  6. Characterization of acoustic lenses with the Foucault test by confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Ahmed Mohamed, E. T.; Abdelrahman, A.; Pluta, M.; Grill, W.

    2010-03-01

    In this work, the Foucault knife-edge test, which has traditionally been known as the classic test for optical imaging devices, is used to characterize an acoustic lens for operation at 1.2 GHz. A confocal laser scanning microscope (CLSM) was used as the illumination and detection device utilizing its pinhole instead of the classical knife edge that is normally employed in the Foucault test. Information about the geometrical characteristics, such as the half opening angle of the acoustic lens, were determined as well as the quality of the calotte of the lens used for focusing. The smallest focal spot size that could be achieved with the examined lens employed as a spherical reflector was found to be about 1 μm. By comparison to the idealized resolution a degradation of about a factor of 2 can be deduced. This limits the actual quality of the acoustic focus.

  7. Research integrity and rights of indigenous peoples: appropriating Foucault's critique of knowledge/power.

    PubMed

    Swazo, Norman K

    2005-09-01

    In this paper I appropriate the philosophical critique of Michel Foucault as it applies to the engagement of Western science and indigenous peoples in the context of biomedical research. The science of population genetics, specifically as pursued in the Human Genome Diversity Project, is the obvious example to illustrate (a) the contraposition of modern science and 'indigenous science', (b) the tendency to depreciate and marginalize indigenous knowledge systems, and (c) the subsumption of indigenous moral preferences in the juridical armature of international human rights law. I suggest that international bioethicists may learn from Foucault's critique, specifically of the need for vigilance about the knowledge/power relation expressed by the contraposition of modern science and 'indigeneity'. PMID:16137604

  8. Raindrop oscillations

    NASA Technical Reports Server (NTRS)

    Beard, K. V.

    1982-01-01

    A model of the change in shape of a raindrop is presented. Raindrops measured by two orthogonal cameras were classified by shape and orientation to determine the nature of the oscillation. A physical model based on potential energy was then developed to study the amplitude variation of oscillating drops. The model results show that oscillations occur about the equilibrium axis ratio, but the time average axis ratio if significantly more spherical for large amplitudes because of asymmetry in the surface potential energy. A generalization of the model to oscillations produced by turbulence yields average axis ratios that are consistent with the camera measurements. The model results for average axis ratios were applied to rainfall studies with a dual polarized radar.

  9. Microelectronic oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1969-01-01

    Bipolar transistor operated in a grounded base configuration is used as the inductor in a microelectronic oscillator. This configuration is employed using thin-film hybrid technology and is also applicable to monolithic technology.

  10. Power oscillator

    DOEpatents

    Gitsevich, Aleksandr

    2001-01-01

    An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  11. Differential phase microscope and micro-tomography with a Foucault knife-edge scanning filter

    NASA Astrophysics Data System (ADS)

    Watanabe, N.; Hashizume, J.; Goto, M.; Yamaguchi, M.; Tsujimura, T.; Aoki, S.

    2013-10-01

    An x-ray differential phase microscope with a Foucault knife-edge scanning filter was set up at the bending magnet source BL3C, Photon Factory. A reconstructed phase profile from the differential phase image of an aluminium wire at 5.36 keV was fairly good agreement with the numerical simulation. Phase tomography of a biological specimen, such as an Artemia cyst, could be successfully demonstrated.

  12. Evaluation of number concentration quantification by single-particle inductively coupled plasma mass spectrometry: microsecond vs. millisecond dwell times.

    PubMed

    Abad-Álvaro, Isabel; Peña-Vázquez, Elena; Bolea, Eduardo; Bermejo-Barrera, Pilar; Castillo, Juan R; Laborda, Francisco

    2016-07-01

    The quality of the quantitative information in single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) depends directly on the number concentration of the nanoparticles in the sample analyzed, which is proportional to the flux of nanoparticles through the plasma. Particle number concentrations must be selected in accordance with the data acquisition frequency, to control the precision from counting statistics and the bias, which is produced by the occurrence of multiple-particle events recorded as single-particle events. With quadrupole mass spectrometers, the frequency of data acquisition is directly controlled by the dwell time. The effect of dwell times from milli- to microseconds (10 ms, 5 ms, 100 μs, and 50 μs) on the quality of the quantitative data has been studied. Working with dwell times in the millisecond range, precision figures about 5 % were achieved, whereas using microsecond dwell times, the suitable fluxes of nanoparticles are higher and precision was reduced down to 1 %; this was independent of the dwell time selected. Moreover, due to the lower occurrence of multiple-nanoparticle events, linear ranges are wider when dwell times equal to or shorter than 100 μs are used. A calculation tool is provided to determine the optimal concentration for any instrument or experimental conditions selected. On the other hand, the use of dwell times in the microsecond range reduces significantly the contribution of the background and/or the presence of dissolved species, in comparison with the use of millisecond dwell times. Although the use of dwell times equal to or shorter than 100 μs offers improved performance working in single-particle mode, the use of conventional dwell times (3-10 ms) should not be discarded, once their limitations are known. PMID:27086011

  13. Composition and Sources of Atmospheric Aerosols in a Residential Area of Ireland using Single Particle Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Buckley, Paul; McGillicuddy, Eoin; Arndt, Jovanna; O'Connor, Ian; Healy, Robert; Venables, Dean; Sodeau, John; Wenger, John

    2015-04-01

    The size-resolved chemical composition of single particles is often sufficiently unique to enable association with a particular source. Single particle mass spectra collected using instruments such as the Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) can be used to identify specific sources of particulate matter, both natural and anthropogenic. In this work, an ATOFMS was deployed in a residential area of Killarney, Ireland, during November-December 2014 to investigate the impact of the various sources of particulate matter upon local air quality. Over 500,000 single particle mass spectra were collected in the sampling period and subsequently grouped into distinct "classes" using a K-means clustering procedure. Based on the presence of key marker species in the mass spectra, the particle classes were then attributed to specific sources. The results indicate that particles generated from solid fuel burning accounted for the vast majority (>75%) of those measured during the sampling period, with similar temporal profiles observed for the three main locally available fuel types - coal, peat and wood. Moreover, these particle classes showed a very strong 24-hour cycle with a significant increase during evening and night-time hours, consistent with the use of fires for residential heating. Further scaling of the ATOFMS data was performed to convert particle number to mass concentration thus enabling the relative contributions of each fuel type to ambient PM2.5 levels to be determined. This information is very useful in assessing the impact of different fuel types on local air quality and is essential for the development of effective strategies for reducing particulate emissions.

  14. Correlated motion of electrons on the Au(111) surface: anomalous acoustic surface-plasmon dispersion and single-particle excitations.

    PubMed

    Vattuone, L; Smerieri, M; Langer, T; Tegenkamp, C; Pfnür, H; Silkin, V M; Chulkov, E V; Echenique, P M; Rocca, M

    2013-03-22

    The linear dispersion of the low-dimensional acoustic surface plasmon (ASP) opens perspectives in energy conversion, transport, and confinement far below optical frequencies. Although the ASP exists in a wide class of materials, ranging from metal surfaces and ultrathin films to graphene and topological insulators, its properties are still largely unexplored. Taking Au(111) as a model system, our combined experimental and theoretical study revealed an intriguing interplay between collective and single particle excitations, causing the ASP associated with the Shockley surface state to be embedded within the intraband transitions without losing its sharp character and linear dispersion. PMID:25166849

  15. Effect of particle-vibration coupling on single-particle states: A consistent study within the Skyrme framework

    SciTech Connect

    Colo, Gianluca; Bortignon, Pier Francesco; Sagawa, Hiroyuki

    2010-12-15

    We discuss calculations of the single-particle states in magic nuclei, performed within the particle-vibration coupling (PVC) approach by using consistently the Skyrme effective interaction. The vibrations are calculated within fully self-consistent random-phase approximation and the whole interaction is also used in the PVC vertex. Our main emphasis is therefore the discussion of our results in comparison with those in which some approximation is made. The perspectives for improving current density functional theory (DFT) calculations are also addressed.

  16. Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sevilla, Paloma; Labrador-Páez, Lucía; Wawrzyńczyk, Dominika; Nyk, Marcin; Samoć, Marek; Kar, Ajoy Kumar; MacKenzie, Mark D.; Paterson, Lynn; Jaque, Daniel; Haro-González, Patricia

    2015-12-01

    An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er3+,Yb3+ upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonics.An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er3+,Yb3+ upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as

  17. Normalizing projection images: a study of image normalizing procedures for single particle three-dimensional electron microscopy.

    PubMed

    Sorzano, C O S; de la Fraga, L G; Clackdoyle, R; Carazo, J M

    2004-11-01

    In the process of three-dimensional reconstruction of single particle biological macromolecules several hundreds, or thousands, of projection images are taken from tens or hundreds of independently digitized micrographs. These different micrographs show differences in the background grey level and particle contrast and, therefore, have to be normalized by scaling their pixel values before entering the reconstruction process. In this work several normalization procedures are studied using a statistical comparison framework. We finally show that the use of the different normalization methods affects the reconstruction quality, providing guidance on the choice of normalization procedures. PMID:15450658

  18. THE APPLICATION OF SINGLE PARTICLE AEROSOL MASS SPECTROMETRY FOR THE DETECTION AND IDENTIFICATION OF HIGH EXPLOSIVES AND CHEMICAL WARFARE AGENTS

    SciTech Connect

    Martin, A

    2006-10-23

    Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle ({approx}1 pg) without the need for consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA simulants using one set of operational conditions is established.

  19. A comprehensive simulation framework for imaging single particles and biomolecules at the European X-ray Free-Electron Laser

    NASA Astrophysics Data System (ADS)

    Yoon, Chun Hong; Yurkov, Mikhail V.; Schneidmiller, Evgeny A.; Samoylova, Liubov; Buzmakov, Alexey; Jurek, Zoltan; Ziaja, Beata; Santra, Robin; Loh, N. Duane; Tschentscher, Thomas; Mancuso, Adrian P.

    2016-04-01

    The advent of newer, brighter, and more coherent X-ray sources, such as X-ray Free-Electron Lasers (XFELs), represents a tremendous growth in the potential to apply coherent X-rays to determine the structure of materials from the micron-scale down to the Angstrom-scale. There is a significant need for a multi-physics simulation framework to perform source-to-detector simulations for a single particle imaging experiment, including (i) the multidimensional simulation of the X-ray source; (ii) simulation of the wave-optics propagation of the coherent XFEL beams; (iii) atomistic modelling of photon-material interactions; (iv) simulation of the time-dependent diffraction process, including incoherent scattering; (v) assembling noisy and incomplete diffraction intensities into a three-dimensional data set using the Expansion-Maximisation-Compression (EMC) algorithm and (vi) phase retrieval to obtain structural information. We demonstrate the framework by simulating a single-particle experiment for a nitrogenase iron protein using parameters of the SPB/SFX instrument of the European XFEL. This exercise demonstrably yields interpretable consequences for structure determination that are crucial yet currently unavailable for experiment design.

  20. A comprehensive simulation framework for imaging single particles and biomolecules at the European X-ray Free-Electron Laser.

    PubMed

    Yoon, Chun Hong; Yurkov, Mikhail V; Schneidmiller, Evgeny A; Samoylova, Liubov; Buzmakov, Alexey; Jurek, Zoltan; Ziaja, Beata; Santra, Robin; Loh, N Duane; Tschentscher, Thomas; Mancuso, Adrian P

    2016-01-01

    The advent of newer, brighter, and more coherent X-ray sources, such as X-ray Free-Electron Lasers (XFELs), represents a tremendous growth in the potential to apply coherent X-rays to determine the structure of materials from the micron-scale down to the Angstrom-scale. There is a significant need for a multi-physics simulation framework to perform source-to-detector simulations for a single particle imaging experiment, including (i) the multidimensional simulation of the X-ray source; (ii) simulation of the wave-optics propagation of the coherent XFEL beams; (iii) atomistic modelling of photon-material interactions; (iv) simulation of the time-dependent diffraction process, including incoherent scattering; (v) assembling noisy and incomplete diffraction intensities into a three-dimensional data set using the Expansion-Maximisation-Compression (EMC) algorithm and (vi) phase retrieval to obtain structural information. We demonstrate the framework by simulating a single-particle experiment for a nitrogenase iron protein using parameters of the SPB/SFX instrument of the European XFEL. This exercise demonstrably yields interpretable consequences for structure determination that are crucial yet currently unavailable for experiment design. PMID:27109208

  1. Measurement of internal and external mixtures of test aerosols with a new Single Particle Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wonaschütz, Anna; Hitzenberger, Regina

    2015-04-01

    The mixing state of atmospheric aerosol particles is a very important property affecting processes such as CCN activation and scattering and absorption of light by the particles, but is challenging to determine. A new Single Particle Aerosol Mass Spectrometer (LAAPTOF, AeroMegt GmbH) was tested with regards to its capability of measuring internal and external mixture of aerosols using laboratory generated particles. To create the external mixture, solutions of three different salts in deionized water, and a suspension of carbon black (Cabot Corporation) in a mixture of isopropanol and water were nebulized and individually dried, before being passed into a small mixing chamber. To create the internal mixture, equal parts of each solution/suspension were mixed, fed into a single nebulizer, nebulized and dried. The LAAPTOF sampled from the mixing chamber and recorded mass spectra of individual particles. The analysis shows a heterogeneous ensemble of single particle spectra for the external mixture, and a homogeneous ensemble of spectra for the internal mixture. The ability of a fuzzy clustering algorithm to resolve the difference between the two mixing states was also tested.

  2. A comprehensive simulation framework for imaging single particles and biomolecules at the European X-ray Free-Electron Laser

    DOE PAGESBeta

    Yoon, Chun Hong; Yurkov, Mikhail V.; Schneidmiller, Evgeny A.; Samoylova, Liubov; Buzmakov, Alexey; Jurek, Zoltan; Ziaja, Beata; Santra, Robin; Loh, N. Duane; Tschentscher, Thomas; et al

    2016-04-25

    The advent of newer, brighter, and more coherent X-ray sources, such as X-ray Free-Electron Lasers (XFELs), represents a tremendous growth in the potential to apply coherent X-rays to determine the structure of materials from the micron-scale down to the Angstrom-scale. There is a significant need for a multi-physics simulation framework to perform source-to-detector simulations for a single particle imaging experiment, including (i) the multidimensional simulation of the X-ray source; (ii) simulation of the wave-optics propagation of the coherent XFEL beams; (iii) atomistic modelling of photon-material interactions; (iv) simulation of the time-dependent diffraction process, including incoherent scattering; (v) assembling noisy andmore » incomplete diffraction intensities into a three-dimensional data set using the Expansion-Maximisation-Compression (EMC) algorithm and (vi) phase retrieval to obtain structural information. Furthermore, we demonstrate the framework by simulating a single-particle experiment for a nitrogenase iron protein using parameters of the SPB/SFX instrument of the European XFEL. This exercise demonstrably yields interpretable consequences for structure determination that are crucial yet currently unavailable for experiment design.« less

  3. Determining the 3D orientation of optically trapped upconverting nanorods by in situ single-particle polarized spectroscopy.

    PubMed

    Rodríguez-Sevilla, Paloma; Labrador-Páez, Lucía; Wawrzyńczyk, Dominika; Nyk, Marcin; Samoć, Marek; Kar, Ajoy Kumar; Mackenzie, Mark D; Paterson, Lynn; Jaque, Daniel; Haro-González, Patricia

    2016-01-01

    An approach to unequivocally determine the three-dimensional orientation of optically manipulated NaYF4:Er(3+),Yb(3+) upconverting nanorods (UCNRs) is demonstrated. Long-term immobilization of individual UCNRs inside single and multiple resonant optical traps allow for stable single UCNR spectroscopy studies. Based on the strong polarization dependent upconverted luminescence of UCNRs it is possible to unequivocally determine, in real time, their three-dimensional orientation when optically trapped. In single-beam traps, polarized single particle spectroscopy has concluded that UCNRs orientate parallel to the propagation axis of the trapping beam. On the other hand, when multiple-beam optical tweezers are used, single particle polarization spectroscopy demonstrated how full spatial control over UCNR orientation can be achieved by changing the trap-to-trap distance as well as the relative orientation between optical traps. All these results show the possibility of real time three-dimensional manipulation and tracking of anisotropic nanoparticles with wide potential application in modern nanobiophotonics. PMID:26607763

  4. A comprehensive simulation framework for imaging single particles and biomolecules at the European X-ray Free-Electron Laser

    PubMed Central

    Yoon, Chun Hong; Yurkov, Mikhail V.; Schneidmiller, Evgeny A.; Samoylova, Liubov; Buzmakov, Alexey; Jurek, Zoltan; Ziaja, Beata; Santra, Robin; Loh, N. Duane; Tschentscher, Thomas; Mancuso, Adrian P.

    2016-01-01

    The advent of newer, brighter, and more coherent X-ray sources, such as X-ray Free-Electron Lasers (XFELs), represents a tremendous growth in the potential to apply coherent X-rays to determine the structure of materials from the micron-scale down to the Angstrom-scale. There is a significant need for a multi-physics simulation framework to perform source-to-detector simulations for a single particle imaging experiment, including (i) the multidimensional simulation of the X-ray source; (ii) simulation of the wave-optics propagation of the coherent XFEL beams; (iii) atomistic modelling of photon-material interactions; (iv) simulation of the time-dependent diffraction process, including incoherent scattering; (v) assembling noisy and incomplete diffraction intensities into a three-dimensional data set using the Expansion-Maximisation-Compression (EMC) algorithm and (vi) phase retrieval to obtain structural information. We demonstrate the framework by simulating a single-particle experiment for a nitrogenase iron protein using parameters of the SPB/SFX instrument of the European XFEL. This exercise demonstrably yields interpretable consequences for structure determination that are crucial yet currently unavailable for experiment design. PMID:27109208

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

    PubMed

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

    2014-06-01

    Superior brightness of fluorescent nanoparticles places them far ahead of the classical fluorescent dyes in the field of biological imaging. However, for in vivo applications, inorganic nanoparticles, such as quantum dots, are limited due to the lack of biodegradability. Nano-emulsions encapsulating high concentrations of organic dyes are an attractive alternative, but classical fluorescent dyes are inconvenient due to their poor solubility in the oil and their tendency to form non-fluorescent aggregates. This problem was solved here for a cationic cyanine dye (DiI) by substituting its perchlorate counterion for a bulky and hydrophobic tetraphenylborate. This new dye salt, due to its exceptional oil solubility, could be loaded at 8 wt% concentration into nano-droplets of controlled size in the range 30-90 nm. Our 90 nm droplets, which contained >10,000 cyanine molecules, were >100-fold brighter than quantum dots. This extreme brightness allowed, for the first time, single-particle tracking in the blood flow of live zebrafish embryo, revealing both the slow and fast phases of the cardiac cycle. These nano-droplets showed minimal cytotoxicity in cell culture and in the zebrafish embryo. The concept of counterion-based dye loading provides a new effective route to ultra-bright lipid nanoparticles, which enables tracking single particles in live animals, a new dimension of in vivo imaging. PMID:24661553

  6. Programmable Oscillator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Lee, Clement G.; Nguyen, Huy

    2011-01-01

    A programmable oscillator is a frequency synthesizer with an output phase that tracks an arbitrary function. An offset, phase-locked loop circuit is used in combination with an error control feedback loop to precisely control the output phase of the oscillator. To down-convert the received signal, several stages of mixing may be employed with the compensation for the time-base distortion of the carrier occurring at any one of those stages. In the Goldstone Solar System Radar (GSSR), the compensation occurs in the mixing from an intermediate frequency (IF), whose value is dependent on the station and band, to a common IF used in the final stage of down-conversion to baseband. The programmable oscillator (PO) is used in the final stage of down-conversion to generate the IF, along with a time-varying phase component that matches the time-base distortion of the carrier, thus removing it from the final down-converted signal.

  7. Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-04-01

    Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and

  8. Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

    2013-09-01

    Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal-optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal

  9. ORBXYZ: a 3D single-particle orbit code for following charged-particle trajectories in equilibrium magnetic fields

    SciTech Connect

    Anderson, D.V.; Cohen, R.H.; Ferguson, J.R.; Johnston, B.M.; Sharp, C.B.; Willmann, P.A.

    1981-06-30

    The single particle orbit code, TIBRO, has been modified extensively to improve the interpolation methods used and to allow use of vector potential fields in the simulation of charged particle orbits on a 3D domain. A 3D cubic B-spline algorithm is used to generate spline coefficients used in the interpolation. Smooth and accurate field representations are obtained. When vector potential fields are used, the 3D cubic spline interpolation formula analytically generates the magnetic field used to push the particles. This field has del.BETA = 0 to computer roundoff. When magnetic induction is used the interpolation allows del.BETA does not equal 0, which can lead to significant nonphysical results. Presently the code assumes quadrupole symmetry, but this is not an essential feature of the code and could be easily removed for other applications. Many details pertaining to this code are given on microfiche accompanying this report.

  10. Electron counting and beam-induced motion correction enable near atomic resolution single particle cryoEM

    PubMed Central

    Li, Xueming; Mooney, Paul; Zheng, Shawn; Booth, Chris; Braunfeld, Michael B.; Gubbens, Sander; Agard, David A.; Cheng, Yifan

    2013-01-01

    In recent work with large high symmetry viruses, single particle electron cryomicroscopy (cryoEM) has reached the milestone of determining near atomic resolution structures by allowing direct fitting of atomic models into experimental density maps. However, achieving this goal with smaller particles of lower symmetry remains extraordinarily challenging. Using a newly developed single electron counting detector, we confirm that electron beam induced motion significantly degrades resolution and, importantly, show how the combination of rapid readout and nearly noiseless electron counting allow image blurring to be corrected to subpixel accuracy. Thus, intrinsic image information can be restored to high resolution (Thon rings visible to ~3 Å). Using this approach we determined a 3.3 Å resolution structure of a ~700 kDa protein with D7 symmetry showing clear side chain density. Our method greatly enhances image quality and data acquisition efficiency - key bottlenecks in applying near atomic resolution cryoEM to a broad range of protein samples. PMID:23644547

  11. Single Particle Deformation and Analysis of Silica-Coated Gold Nanorods before and after Femtosecond Laser Pulse Excitation.

    PubMed

    Albrecht, Wiebke; Deng, Tian-Song; Goris, Bart; van Huis, Marijn A; Bals, Sara; van Blaaderen, Alfons

    2016-03-01

    We performed single particle deformation experiments on silica-coated gold nanorods under femtosecond (fs) illumination. Changes in the particle shape were analyzed by electron microscopy and associated changes in the plasmon resonance by electron energy loss spectroscopy. Silica-coated rods were found to be more stable compared to uncoated rods but could still be deformed via an intermediate bullet-like shape for silica shell thicknesses of 14 nm. Changes in the size ratio of the rods after fs-illumination resulted in blue-shifting of the longitudinal plasmon resonances. Two-dimensional spatial mapping of the plasmon resonances revealed that the flat side of the bullet-like particles showed a less pronounced longitudinal plasmonic electric field enhancement. These findings were confirmed by finite-difference time-domain (FDTD) simulations. Furthermore, at higher laser fluences size reduction of the particles was found as well as for particles that were not completely deformed yet. PMID:26871607

  12. Graphene oxide-encoded Ag nanoshells with single-particle detection sensitivity towards cancer cell imaging based on SERRS.

    PubMed

    Yim, DaBin; Kang, Homan; Jeon, Su-Ji; Kim, Hye-In; Yang, Jin-Kyoung; Kang, Tae Wook; Lee, Sangyeop; Choo, Jaebum; Lee, Yoon-Sik; Kim, Jin Woong; Kim, Jong-Ho

    2015-05-21

    Developing ultrasensitive Raman nanoprobes is one of the emerging interests in the field of biosensing and bioimaging. Herein, we constructed a new type of surface-enhanced resonance Raman scattering nanoprobe composed of an Ag nanoshell as a surface-enhanced Raman scattering-active nanostructure, which was encapsulated with 4,7,10-trioxa-1,13-tridecanediamine-functionalized graphene oxide as an ultrasensitive Raman reporter exhibiting strong resonance Raman scattering including distinct D and G modes. The designed nanoprobe was able to produce much more intense and simpler Raman signals even at a single particle level than the Ag nanoshell bearing a well-known Raman reporter, which is beneficial for the sensitive detection of a target in a complex biological system. Finally, this ultrasensitive nanoprobe successfully demonstrated its potential for bioimaging of cancer cells using Raman spectroscopy. PMID:25811703

  13. Validation of Gold and Silver Nanoparticle Analysis in Fruit Juices by Single-Particle ICP-MS without Sample Pretreatment.

    PubMed

    Witzler, Markus; Küllmer, Fabian; Hirtz, Annika; Günther, Klaus

    2016-05-25

    With the increasing use of nanoparticles in consumer products, the need for validated quantitation methods also rises. This becomes even more urgent because the risks of nanomaterials are still not conclusively assessed. Fast, accurate, and robust single-particle (sp) ICP-MS is a promising technique as it is capable of counting and sizing particles at very low concentrations at the same time. Another feature is the simultaneous distinction between dissolved and particulate analytes. The present study shows, for the first time to our knowledge, a method validation for the rapid analysis of silver and gold nanoparticles with sp-ICP-MS in fruit juices without sample preparation. The investigated matrices water, orange juice, and apple juice were spiked with particles and only diluted prior to measurement without using a digestion reagent. The validations regarding particle size are successful according to the German GTFCh's guideline with deviations of accuracy and precision below 15%. PMID:27132879

  14. Intra-Nuclear Single-Particle Tracking (I-SPT) to Reveal the Functional Architecture of Chromosomes.

    PubMed

    Récamier, Vincent

    2016-01-01

    Chromosome architecture needs to be investigated in relation with the chemical function of DNA. The kinetics of gene expression, DNA replication, and repair are driven by the mechanisms by which a functional nuclear protein finds its substrate in the nucleus. Single-particle tracking (SPT) is a method to quantify fluorescent molecules dynamics from the tracks of the single molecules recorded by high-resolution microscopes. SPT offers direct observation of the movement and single-molecule resolution. Usually SPT is performed on membranes because of higher contrast. Here, we introduce a novel method to record the trajectories of weakly fluorescent molecules in the nucleus of living cells. I-SPT uses some specific detection and analysis tools to enable the computation of reliable statistics on nuclear particle movement. PMID:27283314

  15. Impact of and correction for instrument sensitivity drift on nanoparticle size measurements by single-particle ICP-MS.

    PubMed

    El Hadri, Hind; Petersen, Elijah J; Winchester, Michael R

    2016-07-01

    The effect of ICP-MS instrument sensitivity drift on the accuracy of nanoparticle (NP) size measurements using single particle (sp)ICP-MS is investigated. Theoretical modeling and experimental measurements of the impact of instrument sensitivity drift are in agreement and indicate that drift can impact the measured size of spherical NPs by up to 25 %. Given this substantial bias in the measured size, a method was developed using an internal standard to correct for the impact of drift and was shown to accurately correct for a decrease in instrument sensitivity of up to 50 % for 30 and 60 nm gold nanoparticles. Graphical Abstract Correction of nanoparticle size measurement by spICP-MS using an internal standard. PMID:26894759

  16. Expansion-maximization-compression algorithm with spherical harmonics for single particle imaging with x-ray lasers

    NASA Astrophysics Data System (ADS)

    Flamant, Julien; Le Bihan, Nicolas; Martin, Andrew V.; Manton, Jonathan H.

    2016-05-01

    In three-dimensional (3D) single particle imaging with x-ray free-electron lasers, particle orientation is not recorded during measurement but is instead recovered as a necessary step in the reconstruction of a 3D image from the diffraction data. Here we use harmonic analysis on the sphere to cleanly separate the angular and radial degrees of freedom of this problem, providing new opportunities to efficiently use data and computational resources. We develop the expansion-maximization-compression algorithm into a shell-by-shell approach and implement an angular bandwidth limit that can be gradually raised during the reconstruction. We study the minimum number of patterns and minimum rotation sampling required for a desired angular and radial resolution. These extensions provide new avenues to improve computational efficiency and speed of convergence, which are critically important considering the very large datasets expected from experiment.

  17. Pt-Au Triangular Nanoprisms with Strong Dipole Plasmon Resonance for Hydrogen Generation Studied by Single-Particle Spectroscopy.

    PubMed

    Lou, Zaizhu; Fujitsuka, Mamoru; Majima, Tetsuro

    2016-06-28

    Three anisotropic Pt-covered, Pt-edged, and Pt-tipped Au triangular nanoprisms (TNPs) were prepared by controlling the overgrowth of Pt as photocatalysts for H2 generation. With strong electric field and more interface for the hot electrons transfer, the H2 generation rate of Pt-edged Au TNPs was 3 and 5 times higher than those of Pt-tipped and Pt-covered Au TNPs. Single-particle photoluminescence (PL) spectra and finite-difference-time-domain (FDTD) simulations demonstrated that dipole surface plasmon resonance (DSPR) of Au TNPs enhanced the hot electrons transfer from Au to Pt leading to H2 generation. SPR bands of Au TNPs depending on the size play an important role on the photocatalytic activity of Pt-edged Au TNPs. PMID:27212221

  18. Single Particle Deformation and Analysis of Silica-Coated Gold Nanorods before and after Femtosecond Laser Pulse Excitation

    PubMed Central

    2016-01-01

    We performed single particle deformation experiments on silica-coated gold nanorods under femtosecond (fs) illumination. Changes in the particle shape were analyzed by electron microscopy and associated changes in the plasmon resonance by electron energy loss spectroscopy. Silica-coated rods were found to be more stable compared to uncoated rods but could still be deformed via an intermediate bullet-like shape for silica shell thicknesses of 14 nm. Changes in the size ratio of the rods after fs-illumination resulted in blue-shifting of the longitudinal plasmon resonances. Two-dimensional spatial mapping of the plasmon resonances revealed that the flat side of the bullet-like particles showed a less pronounced longitudinal plasmonic electric field enhancement. These findings were confirmed by finite-difference time-domain (FDTD) simulations. Furthermore, at higher laser fluences size reduction of the particles was found as well as for particles that were not completely deformed yet. PMID:26871607

  19. Super-resolution imaging-based single particle tracking reveals dynamics of nanoparticle internalization by live cells.

    PubMed

    Li, Yiming; Shang, Li; Nienhaus, G Ulrich

    2016-04-14

    By combining super-resolution photoactivation localization microscopy with single particle tracking, we have visualized the endocytic process in the live-cell environment with nanoparticles (NPs) of different size and surface functionalization. This allowed us to analyze the dynamics of NPs interacting with cells with high spatial and temporal resolution. We identified two distinctly different types of pathways by which NPs are internalized via clathrin-coated pits (CCPs). Predominantly, NPs first bind to the membrane and, subsequently, CCPs form at this site. However, there are also instances where a NP diffuses on the membrane and utilizes a preformed CCP. Moreover, we have applied this new method to further explore the effects of size and surface functionalization on the NP dynamics on the plasma membrane and the ensuing endocytosis. PMID:27001905

  20. [Ethics and medicine in Michel Foucault: the humanistic dimension of medicine derived from a genealogy of morality].

    PubMed

    Gomes, Benjamim

    2005-01-01

    The article presents the results of a doctoral dissertation defended at the Universidad de Salamanca, based on Foucault's final decade of writings. If Foucault's goal in writing The History of Sexuality was to fashion a genealogy of ethics, my goal in analyzing this book, along with his other writings, is to demonstrate his last contribution to the history of medicine. He moves from a conception of power over others towards a conception of power over oneself, an exclusive terrain of ancient Greek morality. As a thinker who tries to understand today's problems by going to their roots, Foucault develops less a history than a philosophy of history. Considered an anti-humanist, he leaves us with a portrait of a wholly ethical-humanistic medicine. PMID:17500131

  1. Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pits

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le; Houck, Joshua D. T.; Clark, Pamela A.; Pinnick, Ronald G.

    2013-08-01

    A single-particle fluorescence spectrometer (SPFS) and an aerodynamic particle sizer were used to measure the fluorescence spectra and particle size distribution from the particulate emissions of 12 different burning materials in a tube furnace to simulate open-air burning of garbage. Although the particulate emissions are likely dominated by particles <1 μm diameter, only the spectra of supermicron particles were measured here. The overall fluorescence spectral profiles exhibit either one or two broad bands peaked around 300-450 nm within the 280-650 nm spectral range, when the particles are illuminated with a 263-nm laser. Different burning materials have different profiles, some of them (cigarette, hair, uniform, paper, and plastics) show small changes during the burning process, and while others (beef, bread, carrot, Styrofoam, and wood) show big variations, which initially exhibit a single UV peak (around 310-340 nm) and a long shoulder in visible, and then gradually evolve into a bimodal spectrum with another visible peak (around 430-450 nm) having increasing intensity during the burning process. These spectral profiles could mainly derive from polycyclic aromatic hydrocarbons with the combinations of tyrosine-like, tryptophan-like, and other humic-like substances. About 68 % of these single-particle fluorescence spectra can be grouped into 10 clustered spectral templates that are derived from the spectra of millions of atmospheric aerosol particles observed in three locations; while the others, particularly these bimodal spectra, do not fall into any of the 10 templates. Therefore, the spectra from particulate emissions of burning materials can be easily discriminated from that of common atmospheric aerosol particles. The SFFS technology could be a good tool for monitoring burning pit emissions and possibly for distinguishing them from atmospheric aerosol particles.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  3. Characterization of the single particle mixing state of individual ship plume events measured at the Port of Los Angeles.

    PubMed

    Ault, Andrew P; Gaston, Cassandra I; Wang, Ying; Dominguez, Gerardo; Thiemens, Mark H; Prather, Kimberly A

    2010-03-15

    Ship emissions contribute significantly to gaseous and particulate pollution worldwide. To better understand the impact of ship emissions on air quality, measurements of the size-resolved chemistry of individual particles in ship emissions were made at the Port of Los Angeles using real-time, single-particle mass spectrometry. Ship plumes were identified through a combination of ship position information and measurements of gases and aerosol particles at a site 500 m from the center of the main shipping channel at the Port of Los Angeles. Single particles containing mixtures of organic carbon, vanadium, and sulfate (OC-V-sulfate) resulted from residual fuel combustion (i.e., bunker fuel), whereas high quantities of fresh soot particles (when OC-V-sulfate particles were not present) represented distinct markers for plumes from distillate fuel combustion (i.e., diesel fuel) from ships as well as trucks in the port area. DC-V-sulfate particles from residual fuel combustion contained significantly higher levels of sulfate and sulfuric acid than plume particles containing no vanadium. These associations may be due to vanadium (or other metals such as iron) in the fuel catalyzing the oxidation of S0(2) to produce sulfate and sulfuric acid on these particles. Enhanced sulfate production on OC-V-sulfate ship emission particles would help explain some of the higher than expected sulfate levels measured in California compared to models based on emissions inventories and typical sulfate production pathways. Understanding the overall impact of ships emissions is critical for controlling regional air quality in the many populated coastal regions of the world. PMID:20148582

  4. Super-resolution imaging-based single particle tracking reveals dynamics of nanoparticle internalization by live cells

    NASA Astrophysics Data System (ADS)

    Li, Yiming; Shang, Li; Nienhaus, G. Ulrich

    2016-03-01

    By combining super-resolution photoactivation localization microscopy with single particle tracking, we have visualized the endocytic process in the live-cell environment with nanoparticles (NPs) of different size and surface functionalization. This allowed us to analyze the dynamics of NPs interacting with cells with high spatial and temporal resolution. We identified two distinctly different types of pathways by which NPs are internalized via clathrin-coated pits (CCPs). Predominantly, NPs first bind to the membrane and, subsequently, CCPs form at this site. However, there are also instances where a NP diffuses on the membrane and utilizes a preformed CCP. Moreover, we have applied this new method to further explore the effects of size and surface functionalization on the NP dynamics on the plasma membrane and the ensuing endocytosis.By combining super-resolution photoactivation localization microscopy with single particle tracking, we have visualized the endocytic process in the live-cell environment with nanoparticles (NPs) of different size and surface functionalization. This allowed us to analyze the dynamics of NPs interacting with cells with high spatial and temporal resolution. We identified two distinctly different types of pathways by which NPs are internalized via clathrin-coated pits (CCPs). Predominantly, NPs first bind to the membrane and, subsequently, CCPs form at this site. However, there are also instances where a NP diffuses on the membrane and utilizes a preformed CCP. Moreover, we have applied this new method to further explore the effects of size and surface functionalization on the NP dynamics on the plasma membrane and the ensuing endocytosis. Electronic supplementary information (ESI) available: Experimental section, supporting figures and videos. See DOI: 10.1039/c6nr01495j

  5. Single-particle cryoEM analysis at near-atomic resolution from several thousand asymmetric subunits.

    PubMed

    Passos, Dario Oliveira; Lyumkis, Dmitry

    2015-11-01

    A single-particle cryoEM reconstruction of the large ribosomal subunit from Saccharomyces cerevisiae was obtained from a dataset of ∼75,000 particles. The gold-standard and frequency-limited approaches to single-particle refinement were each independently used to determine orientation parameters for the final reconstruction. Both approaches showed similar resolution curves and nominal resolution values for the 60S dataset, estimated at 2.9 Å. The amount of over-fitting present during frequency-limited refinement was quantitatively analyzed using the high-resolution phase-randomization test, and the results showed no apparent over-fitting. The number of asymmetric subunits required to reach specific resolutions was subsequently analyzed by refining subsets of the data in an ab initio manner. With our data collection and processing strategies, sub-nanometer resolution was obtained with ∼200 asymmetric subunits (or, equivalently for the ribosomal subunit, particles). Resolutions of 5.6 Å, 4.5 Å, and 3.8 Å were reached with ∼1000, ∼1600, and ∼5000 asymmetric subunits, respectively. At these resolutions, one would expect to detect alpha-helical pitch, separation of beta-strands, and separation of Cα atoms, respectively. Using this map, together with strategies for ab initio model building and model refinement, we built a region of the ribosomal protein eL6, which was missing in previous models of the yeast ribosome. The relevance for more routine high-resolution structure determination is discussed. PMID:26470814

  6. Detection of zinc oxide and cerium dioxide nanoparticles during drinking water treatment by rapid single particle ICP-MS methods.

    PubMed

    Donovan, Ariel R; Adams, Craig D; Ma, Yinfa; Stephan, Chady; Eichholz, Todd; Shi, Honglan

    2016-07-01

    Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO2 NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO2 NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation. PMID:26960902

  7. Foucault's method for measuring the speed of light with modern apparatus

    NASA Astrophysics Data System (ADS)

    Vörös, Zoltán; Weihs, Gregor

    2015-05-01

    In this paper, we introduce two simple and inexpensive, yet quite accurate versions of the well-known Foucault method for measuring the speed of light. In a compact footprint of just 20 cm by 270 cm with readily available laboratory items, a rotating mirror taken from a laser printer, and a webcam, we obtained c=296\\720+/- 3000 km s-1, and c=302\\295+/- 3000 km s-1, respectively, both within less than a per cent of the defined value. The experiment also prepares students for extracting data through image processing.

  8. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  9. Solar Oscillations

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas

    2004-01-01

    Oscillations were first detected in the solar photosphere in 1962 by Leighton and students. In 1970 it was calculated that these oscillations, with a period near five minutes, were the manifestations of acoustic waves trapped in the interior. The subsequent measurements of the frequencies of global oscillation modes from the spatio-temporal power spectrum of the waves made possible the refinement of solar interior models. Over the years, increased understanding of the nuclear reaction rates, the opacity, the equation of state, convection, and gravitational settling have resulted. Mass flows shift the frequencies of modes leading to very accurate measurements of the interior rotation as a function of radius and latitude. In recent years, analogues of terrestrial seismology have led to a tomography of the interior, including measurements of global north-south flows and flow and wave speed measurements below features such as sunspots. The future of helioseismology seems bright with the approval of NASA's Solar Dynamics Observatory mission, to be launched in 2008.

  10. Casimir-Foucault interaction: Free energy and entropy at low temperature

    NASA Astrophysics Data System (ADS)

    Intravaia, Francesco; Ellingsen, Simen Å.; Henkel, Carsten

    2010-09-01

    It was recently found that thermodynamic anomalies which arise in the Casimir effect between metals described by the Drude model can be attributed to the interaction of fluctuating Foucault (or eddy) currents [F. Intravaia and C. Henkel, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.130405 103, 130405 (2009).] We focus on the transverse electric (TE) polarization, where the anomalies occur, and show explicitly that the two leading terms of the low-temperature correction to the Casimir free energy of interaction between two plates are identical to those pertaining to the Foucault current interaction alone, up to a correction which is very small for good metals. Moreover, a mode density along real frequencies is introduced, showing that the TE contribution to the Casimir free energy, as given by the Lifshitz theory, separates in a natural manner into contributions from eddy currents and propagating cavity modes, respectively. The latter have long been known to be of little importance to the low-temperature Casimir anomalies. This convincingly demonstrates that eddy current modes are responsible for the large temperature correction to the Casimir effect between Drude metals, predicted by the Lifshitz theory, but not observed in experiments.

  11. Single-particle spectral density of the unitary Fermi gas: Novel approach based on the operator product expansion, sum rules and the maximum entropy method

    SciTech Connect

    Gubler, Philipp; Yamamoto, Naoki; Hatsuda, Tetsuo; Nishida, Yusuke

    2015-05-15

    Making use of the operator product expansion, we derive a general class of sum rules for the imaginary part of the single-particle self-energy of the unitary Fermi gas. The sum rules are analyzed numerically with the help of the maximum entropy method, which allows us to extract the single-particle spectral density as a function of both energy and momentum. These spectral densities contain basic information on the properties of the unitary Fermi gas, such as the dispersion relation and the superfluid pairing gap, for which we obtain reasonable agreement with the available results based on quantum Monte-Carlo simulations.

  12. Replacing the Singlet Spinor of the EPR-B Experiment in the Configuration Space with Two Single-Particle Spinors in Physical Space

    NASA Astrophysics Data System (ADS)

    Gondran, Michel; Gondran, Alexandre

    2016-04-01

    Recently, for spinless non-relativistic particles, Norsen (Found Phys 40:1858-1884, 2010) and Norsen et al. (Synthese 192:3125-3151, 2015) show that in the de Broglie-Bohm interpretation it is possible to replace the wave function in the configuration space by single-particle wave functions in physical space. In this paper, we show that this replacment of the wave function in the configuration space by single-particle functions in the 3D-space is also possible for particles with spin, in particular for the particles of the EPR-B experiment, the Bohm version of the Einstein-Podolsky-Rosen experiment.

  13. Single Particle Plasmon Sensors as Label-Free Technique To Monitor MinDE Protein Wave Propagation on Membranes.

    PubMed

    Lambertz, Christina; Martos, Ariadna; Henkel, Andreas; Neiser, Andreas; Kliesch, Torben-Tobias; Janshoff, Andreas; Schwille, Petra; Sönnichsen, Carsten

    2016-06-01

    We use individual gold nanorods as pointlike detectors for the intrinsic dynamics of an oscillating biological system. We chose the pattern forming MinDE protein system from Escherichia coli (E. coli), a prominent example for self-organized chemical oscillations of membrane-associated proteins that are involved in the bacterial cell division process. Similar to surface plasmon resonance (SPR), the gold nanorods report changes in their protein surface coverage without the need for fluorescence labeling, a technique we refer to as NanoSPR. Comparing the dynamics for fluorescence labeled and unlabeled proteins, we find a reduction of the oscillation period by about 20%. The absence of photobleaching allows us to investigate Min proteins attaching and detaching from lipid coated gold nanorods with an unprecedented bandwidth of 100 ms time resolution and 1 h observation time. The long observation reveals small changes of the oscillation period over time. Averaging many cycles yields the precise wave profile that exhibits the four phases suggested in previous reports. Unexpected from previous fluorescence-based studies, we found an immobile static protein layer not dissociating during the oscillation cycle. Hence, NanoSPR is an attractive label-free real-time technique for the local investigation of molecular dynamics with high observation bandwidth. It gives access to systems, which cannot be fluorescently labeled, and resolves local dynamics that would average out over the sensor area used in conventional SPR. PMID:27172130

  14. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    SciTech Connect

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M.; Lynden-Bell, Ruth M.

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF{sub 6}]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO{sub 3}]{sup −} and [PF{sub 6}]{sup −} anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca{sup 2

  15. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    NASA Astrophysics Data System (ADS)

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M.; Gallego, Luis J.; Varela, Luis M.

    2015-09-01

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3]- and [PF6]- anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca2+ cations. No qualitative difference with

  16. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids.

    PubMed

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M; Gallego, Luis J; Varela, Luis M

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF6]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO3](-) and [PF6](-) anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca(2+) cations. No qualitative

  17. A Paradox of Freedom in "Becoming Oneself through Learning": Foucault's Response to His Educators

    ERIC Educational Resources Information Center

    Stickney, Jeff

    2013-01-01

    In his later lectures, published as "The Hermeneutics of the Subject," Michel Foucault surveys different modalities of obtaining "truth" about one's self and the world: from Socrates to the Cynics, Stoics, Epicureans and early church writers. Genealogically tracing this opposition between knowing "self and…

  18. Dielectric spectra of supercooled halogenobenzene-decalin solutions: A single particle site model for relaxation and resonant behaviors

    NASA Astrophysics Data System (ADS)

    Reid, C. J.; Vij, J. K.

    1983-11-01

    Dielectric loss spectra for 10% V/V decalin solutions of PhBr, PhCl, and PhF have been measured using a precision, coaxial three-terminal cell at temperatures from 77 to 150 K and for a frequency range 200 Hz-5 MHz. These results which are in agreement and which extend previous measurements, are interpreted within the context of cosinal itinerant oscillation. Data for PhBr decalin are simulated using a model of a single Brownian particle rotating in the presence of a cosinal potential, which is a special case of the cosine itinerant oscillator model.

  19. Confined Diffusion Without Fences of a G-Protein-Coupled Receptor as Revealed by Single Particle Tracking

    PubMed Central

    Daumas, Frédéric; Destainville, Nicolas; Millot, Claire; Lopez, André; Dean, David; Salomé, Laurence

    2003-01-01

    Single particle tracking is a powerful tool for probing the organization and dynamics of the plasma membrane constituents. We used this technique to study the μ-opioid receptor belonging to the large family of the G-protein-coupled receptors involved with other partners in a signal transduction pathway. The specific labeling of the receptor coupled to a T7-tag at its N-terminus, stably expressed in fibroblastic cells, was achieved by colloidal gold coupled to a monoclonal anti T7-tag antibody. The lateral movements of the particles were followed by nanovideomicroscopy at 40 ms time resolution during 2 min with a spatial precision of 15 nm. The receptors were found to have either a slow or directed diffusion mode (10%) or a walking confined diffusion mode (90%) composed of a long-term random diffusion and a short-term confined diffusion, and corresponding to a diffusion confined within a domain that itself diffuses. The results indicate that the confinement is due to an effective harmonic potential generated by long-range attraction between the membrane proteins. A simple model for interacting membrane proteins diffusion is proposed that explains the variations with the domain size of the short-term and long-term diffusion coefficients. PMID:12524289

  20. Nanoscopic substructures of raft-mimetic liquid-ordered membrane domains revealed by high-speed single-particle tracking.

    PubMed

    Wu, Hsiao-Mei; Lin, Ying-Hsiu; Yen, Tzu-Chi; Hsieh, Chia-Lung

    2016-01-01

    Lipid rafts are membrane nanodomains that facilitate important cell functions. Despite recent advances in identifying the biological significance of rafts, nature and regulation mechanism of rafts are largely unknown due to the difficulty of resolving dynamic molecular interaction of rafts at the nanoscale. Here, we investigate organization and single-molecule dynamics of rafts by monitoring lateral diffusion of single molecules in raft-containing reconstituted membranes supported on mica substrates. Using high-speed interferometric scattering (iSCAT) optical microscopy and small gold nanoparticles as labels, motion of single lipids is recorded via single-particle tracking (SPT) with nanometer spatial precision and microsecond temporal resolution. Processes of single molecules partitioning into and escaping from the raft-mimetic liquid-ordered (Lo) domains are directly visualized in a continuous manner with unprecedented clarity. Importantly, we observe subdiffusion of saturated lipids in the Lo domain in microsecond timescale, indicating the nanoscopic heterogeneous molecular arrangement of the Lo domain. Further analysis of the diffusion trajectory shows the presence of nano-subdomains of the Lo phase, as small as 10 nm, which transiently trap the lipids. Our results provide the first experimental evidence of non-uniform molecular organization of the Lo phase, giving a new view of how rafts recruit and confine molecules in cell membranes. PMID:26861908

  1. Source identification of particulate matter collected at underground subway stations in Seoul, Korea using quantitative single-particle analysis

    NASA Astrophysics Data System (ADS)

    Jung, Hae-Jin; Kim, BoWha; Ryu, JiYeon; Maskey, Shila; Kim, Jo-Chun; Sohn, Jongryeul; Ro, Chul-Un

    2010-06-01

    Subway particle samples collected at four underground subway stations in Seoul, Korea were characterized by a single-particle analytical technique, low- Z particle electron probe X-ray microanalysis. To clearly identify indoor sources of subway particles, four sets of samples collected in tunnels, at platforms, near ticket offices, and outdoors were investigated. For the samples collected in tunnels, Fe-containing particles predominate, with relative abundances of 75-91% for the four stations. The amounts of Fe-containing particles decrease as the distance of sampling locations from the tunnel increases. In addition, samples collected at the platform in subway stations with platform screen doors (PSDs) that limit air-mixing between the platform and the tunnel showed marked decreases in relative abundances of Fe-containing particles, clearly indicating that Fe-containing subway particles are generated in the tunnel. PM 10 mass concentration levels are the highest in the tunnels, becoming lower as the distance of sampling locations from the tunnel increases. The extent of the decrease in PM 10 in stations with PSDs is also larger than that in stations without PSDs. The results clearly indicate that Fe-containing particles originating in tunnels predominate in the indoor microenvironment of subway stations, resulting in high indoor PM 10 levels, and that PSDs play a significant role in reducing Fe-containing particles at platforms and near ticket offices.

  2. Direct Analysis of Gold Nanoparticles from Dried Droplets Using Substrate-Assisted Laser Desorption Single Particle-ICPMS.

    PubMed

    Benešová, Iva; Dlabková, Kristýna; Zelenák, František; Vaculovič, Tomáš; Kanický, Viktor; Preisler, Jan

    2016-03-01

    Single particle inductively coupled plasma mass spectrometry (SP-ICPMS) has been generally accepted as a powerful tool in the field of nanoanalysis. The method has usually been restricted to direct nanoparticle (NP) introduction using nebulization or microdroplet generation systems. In this work, AuNPs are introduced into ICPMS by substrate-assisted laser desorption (SALD) directly from a suitable absorbing plastic surface using a commercial ablation cell for the first time. In SALD, desorption of individual NPs is mediated using a frequency-quintupled Nd:YAG laser (213 nm) operated at a rather low laser fluence. Conditions including laser fluence, laser beam scan rate, and carrier gas flow rate were optimized in order to gain the highest AuNP transport efficiency and avoid AuNP disintegration within the laser irradiation. The method was demonstrated on a well-characterized reference material, 56 nm AuNPs with a transport efficiency of 61% and commercially available 86 nm AuNPs. Feasibility of our technique for NP detection and characterization is discussed here, and the results are compared with an established technique, nebulizer SP-ICPMS. PMID:26859790

  3. Impact of Single-Particle Compressibility on the Fluid-Solid Phase Transition for Ionic Microgel Suspensions

    NASA Astrophysics Data System (ADS)

    Pelaez-Fernandez, M.; Souslov, Anton; Lyon, L. A.; Goldbart, P. M.; Fernandez-Nieves, A.

    2015-03-01

    We study ionic microgel suspensions composed of swollen particles for various single-particle stiffnesses. We measure the osmotic pressure π of these suspensions and show that it is dominated by the contribution of free ions in solution. As this ionic osmotic pressure depends on the volume fraction of the suspension ϕ , we can determine ϕ from π , even at volume fractions so high that the microgel particles are compressed. We find that the width of the fluid-solid phase coexistence, measured using ϕ , is larger than its hard-sphere value for the stiffer microgels that we study and progressively decreases for softer microgels. For sufficiently soft microgels, the suspensions are fluidlike, irrespective of volume fraction. By calculating the dependence on ϕ of the mean volume of a microgel particle, we show that the behavior of the phase-coexistence width correlates with whether or not the microgel particles are compressed at the volume fractions corresponding to fluid-solid phase coexistence.

  4. Lipid Diffusion in Supported Lipid Bilayers: A Comparison between Line-Scanning Fluorescence Correlation Spectroscopy and Single-Particle Tracking

    PubMed Central

    Rose, Markus; Hirmiz, Nehad; Moran-Mirabal, Jose M.; Fradin, Cécile

    2015-01-01

    Diffusion in lipid membranes is an essential component of many cellular process and fluorescence a method of choice to study membrane dynamics. The goal of this work was to directly compare two common fluorescence methods, line-scanning fluorescence correlation spectroscopy and single-particle tracking, to observe the diffusion of a fluorescent lipophilic dye, DiD, in a complex five-component mitochondria-like solid-supported lipid bilayer. We measured diffusion coefficients of DFCS ~ 3 μm2 · s−1 and DSPT ~ 2 μm2 · s−1, respectively. These comparable, yet statistically different values are used to highlight the main message of the paper, namely that the two considered methods give access to distinctly different dynamic ranges: D ≳ 1 μm2 · s−1 for FCS and D ≲ 5 μm2 · s−1 for SPT (with standard imaging conditions). In the context of membrane diffusion, this means that FCS allows studying lipid diffusion in fluid membranes, as well as the diffusion of loosely-bound proteins hovering above the membrane. SPT, on the other hand, is ideal to study the motions of membrane-inserted proteins, especially those presenting different conformations, but only allows studying lipid diffusion in relatively viscous membranes, such as supported lipid bilayers and cell membranes. PMID:26610279

  5. Correlation of dual colour single particle trajectories for improved detection and analysis of interactions in living cells.

    PubMed

    Deschout, Hendrik; Martens, Thomas; Vercauteren, Dries; Remaut, Katrien; Demeester, Jo; De Smedt, Stefaan C; Neyts, Kristiaan; Braeckmans, Kevin

    2013-01-01

    Interactions between objects inside living cells are often investigated by looking for colocalization between fluorescence microscopy images that are recorded in separate colours corresponding to the fluorescent label of each object. The fundamental limitation of this approach in the case of dynamic objects is that coincidental colocalization cannot be distinguished from true interaction. Instead, correlation between motion trajectories obtained by dual colour single particle tracking provides a much stronger indication of interaction. However, frequently occurring phenomena in living cells, such as immobile phases or transient interactions, can limit the correlation to small parts of the trajectories. The method presented here, developed for the detection of interaction, is based on the correlation inside a window that is scanned along the trajectories, covering different subsets of the positions. This scanning window method was validated by simulations and, as an experimental proof of concept, it was applied to the investigation of the intracellular trafficking of polymeric gene complexes by endosomes in living retinal pigment epithelium cells, which is of interest to ocular gene therapy. PMID:23965965

  6. Single Particle and PET-based Platform for Identifying Optimal Plasmonic Nano-Heaters for Photothermal Cancer Therapy

    PubMed Central

    Jørgensen, Jesper Tranekjær; Norregaard, Kamilla; Tian, Pengfei; Bendix, Poul Martin; Kjaer, Andreas; Oddershede, Lene B.

    2016-01-01

    Plasmonic nanoparticle-based photothermal cancer therapy is a promising new tool to inflict localized and irreversible damage to tumor tissue by hyperthermia, without harming surrounding healthy tissue. We developed a single particle and positron emission tomography (PET)-based platform to quantitatively correlate the heat generation of plasmonic nanoparticles with their potential as cancer killing agents. In vitro, the heat generation and absorption cross-section of single irradiated nanoparticles were quantified using a temperature sensitive lipid-based assay and compared to their theoretically predicted photo-absorption. In vivo, the heat generation of irradiated nanoparticles was evaluated in human tumor xenografts in mice using 2-deoxy-2-[F-18]fluoro-D-glucose (18F-FDG) PET imaging. To validate the use of this platform, we quantified the photothermal efficiency of near infrared resonant silica-gold nanoshells (AuNSs) and benchmarked this against the heating of colloidal spherical, solid gold nanoparticles (AuNPs). As expected, both in vitro and in vivo the heat generation of the resonant AuNSs performed superior compared to the non-resonant AuNPs. Furthermore, the results showed that PET imaging could be reliably used to monitor early treatment response of photothermal treatment. This multidisciplinary approach provides a much needed platform to benchmark the emerging plethora of novel plasmonic nanoparticles for their potential for photothermal cancer therapy. PMID:27481537

  7. Nuclear mass formula with a finite-range droplet model and a folded-Yukawa single-particle potential

    SciTech Connect

    Moeller, P.; Myers, W.D.; Swiatecki, W.J.; Treiner, J.

    1988-07-01

    We calculate ground-state masses for 4678 nuclei ranging from /sup 16/O to /sup 318/122 by use of a macroscopic-microscopic model, which incorporates several new features. For the macroscopic model we use the finite-range droplet model which we introduced in 1984. The microscopic contribution is taken from a calculation based on a folded-Yukawa single-particle potential. Some new features now incorporated are a new model for the average pairing strength and the solution of the microscopic pairing equations by use of the Lipkin-Nogami method with approximate particle number conservation. To estimate the parameters of the macroscopic model we use an approach that starts by defining the error of a mass formula in a rigorous way, which leads naturally to the use of experimental uncertainties and of the maximum-likelihood method to derive a set of equations for estimating the parameters and error of the theoretical model. By considering 1593 experimental masses from /sup 16/O to /sup 263/106 we estimate the error of the theoretical model to be 0.769 MeV. The model retains its accuracy far from stability and the values of the model parameters are very insensitive to details of the adjustment procedure. copyright 1988 Academic Press, Inc.

  8. Single-particle imaging reveals intraflagellar transport–independent transport and accumulation of EB1 in Chlamydomonas flagella

    PubMed Central

    Harris, J. Aaron; Liu, Yi; Yang, Pinfen; Kner, Peter; Lechtreck, Karl F.

    2016-01-01

    The microtubule (MT) plus-end tracking protein EB1 is present at the tips of cilia and flagella; end-binding protein 1 (EB1) remains at the tip during flagellar shortening and in the absence of intraflagellar transport (IFT), the predominant protein transport system in flagella. To investigate how EB1 accumulates at the flagellar tip, we used in vivo imaging of fluorescent protein–tagged EB1 (EB1-FP) in Chlamydomonas reinhardtii. After photobleaching, the EB1 signal at the flagellar tip recovered within minutes, indicating an exchange with unbleached EB1 entering the flagella from the cell body. EB1 moved independent of IFT trains, and EB1-FP recovery did not require the IFT pathway. Single-particle imaging showed that EB1-FP is highly mobile along the flagellar shaft and displays a markedly reduced mobility near the flagellar tip. Individual EB1-FP particles dwelled for several seconds near the flagellar tip, suggesting the presence of stable EB1 binding sites. In simulations, the two distinct phases of EB1 mobility are sufficient to explain its accumulation at the tip. We propose that proteins uniformly distributed throughout the cytoplasm like EB1 accumulate locally by diffusion and capture; IFT, in contrast, might be required to transport proteins against cellular concentration gradients into or out of cilia. PMID:26631555

  9. Single Particle and PET-based Platform for Identifying Optimal Plasmonic Nano-Heaters for Photothermal Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Jørgensen, Jesper Tranekjær; Norregaard, Kamilla; Tian, Pengfei; Bendix, Poul Martin; Kjaer, Andreas; Oddershede, Lene B.

    2016-08-01

    Plasmonic nanoparticle-based photothermal cancer therapy is a promising new tool to inflict localized and irreversible damage to tumor tissue by hyperthermia, without harming surrounding healthy tissue. We developed a single particle and positron emission tomography (PET)-based platform to quantitatively correlate the heat generation of plasmonic nanoparticles with their potential as cancer killing agents. In vitro, the heat generation and absorption cross-section of single irradiated nanoparticles were quantified using a temperature sensitive lipid-based assay and compared to their theoretically predicted photo-absorption. In vivo, the heat generation of irradiated nanoparticles was evaluated in human tumor xenografts in mice using 2-deoxy-2-[F-18]fluoro-D-glucose (18F-FDG) PET imaging. To validate the use of this platform, we quantified the photothermal efficiency of near infrared resonant silica-gold nanoshells (AuNSs) and benchmarked this against the heating of colloidal spherical, solid gold nanoparticles (AuNPs). As expected, both in vitro and in vivo the heat generation of the resonant AuNSs performed superior compared to the non-resonant AuNPs. Furthermore, the results showed that PET imaging could be reliably used to monitor early treatment response of photothermal treatment. This multidisciplinary approach provides a much needed platform to benchmark the emerging plethora of novel plasmonic nanoparticles for their potential for photothermal cancer therapy.

  10. Separation, detection and characterization of nanomaterials in municipal wastewaters using hydrodynamic chromatography coupled to ICPMS and single particle ICPMS.

    PubMed

    Proulx, Kim; Hadioui, Madjid; Wilkinson, Kevin J

    2016-07-01

    Engineered nanoparticles (ENP) are increasingly being incorporated into consumer products and reaching the environment at a growing rate. Unfortunately, few analytical techniques are available that allow the detection of ENP in complex environmental matrices. The major limitations with existing techniques are their relatively high detection limits and their inability to distinguish ENP from other chemical forms (e.g. ions, dissolved) or from natural colloids. Of the matrices that are considered to be a priority for method development, ENP are predicted to be found at relatively high concentrations in wastewaters and wastewater biosolids. In this paper, we demonstrate the capability of hydrodynamic chromatography (HDC) coupled to inductively coupled plasma mass spectrometry (ICPMS), in its classical and single particle modes (SP ICPMS), to identify ENP in wastewater influents and effluents. The paper first focuses on the detection of standard silver nanoparticles (Ag NP) and their mixtures, showing that significant dissolution of the Ag NP was likely to occur. For the Ag NP, detection limits of 0.03 μg L(-1) were found for the HDC ICPMS whereas 0.1 μg L(-1) was determined for the HDC SP ICPMS (based on results for the 80 nm Ag NP). In the second part of the paper, HDC ICPMS and HDC SP ICPMS were performed on some unspiked natural samples (wastewaters, river water). While nanosilver was below detection limits, it was possible to identify some (likely natural) Cu nanoparticles using the developed separation technology. PMID:26970748

  11. Detection of zinc and lead in water using evaporative preconcentration and single-particle laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Järvinen, Samu T.; Saarela, Jaakko; Toivonen, Juha

    2013-08-01

    A novel laser-induced breakdown spectroscopy (LIBS)-based measurement method for metals in water is demonstrated. In the presented technology a small amount of sodium chloride is dissolved in the sample solution before spraying the sample into a tubular oven. After water removal monodisperse dry NaCl aerosol particles are formed where trace metals are present as additives. A single-particle LIBS analysis is then triggered with a scattering based particle detection system. Benefits are the highly increased metal concentration in the LIBS focal volume and the static NaCl-matrix which can be exploited in the signal processing procedure. Emitted light from the emerged plasma plume is collected with wide angle optics and dispersed with a grating spectrometer. In an aqueous solution, the respective limits of detection for zinc and lead were 0.3 ppm and 0.1 ppm using a relatively low 14 mJ laser pulse energy. Zn/Na peak intensity ratio calibration curve for zinc concentration was also determined and LIBS signal dependence on laser pulse energy was investigated.

  12. Inside versus Outside: Ion Redistribution in Nitric Acid Reacted Sea Spray Aerosol Particles as Determined by Single Particle Analysis (Invited)

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Guasco, T.; Ryder, O. S.; Baltrusaitis, J.; Cuadra-Rodriguez, L. A.; Collins, D. B.; Ruppel, M. J.; Bertram, T. H.; Prather, K. A.; Grassian, V. H.

    2013-12-01

    Sea spray aerosol (SSA) particles were generated under real-world conditions using natural seawater and a unique ocean-atmosphere facility equipped with actual breaking waves or a marine aerosol reference tank (MART) that replicates those conditions. The SSA particles were exposed to nitric acid in situ in a flow tube and the well-known chloride displacement and nitrate formation reaction was observed. However, as discussed here, little is known about how this anion displacement reaction affects the distribution of cations and other chemical constituents within and phase state of individual SSA particles. Single particle analysis of individual SSA particles shows that cations (Na+, K+, Mg2+ and Ca2+) within individual particles undergo a spatial redistribution after heterogeneous reaction with nitric acid, along with a more concentrated layer of organic matter at the surface of the particle. These data suggest that specific ion and aerosol pH effects play an important role in aerosol particle structure in ways that have not been previously recognized. The ordering of organic coatings can impact trace gas uptake, and subsequently impact trace gas budgets of O3 and NOx.

  13. Fluorescent Protein-Tagged Sindbis Virus E2 Glycoprotein Allows Single Particle Analysis of Virus Budding from Live Cells

    PubMed Central

    Jose, Joyce; Tang, Jinghua; Taylor, Aaron B.; Baker, Timothy S.; Kuhn, Richard J.

    2015-01-01

    Sindbis virus (SINV) is an enveloped, mosquito-borne alphavirus. Here we generated and characterized a fluorescent protein-tagged (FP-tagged) SINV and found that the presence of the FP-tag (mCherry) affected glycoprotein transport to the plasma membrane whereas the specific infectivity of the virus was not affected. We examined the virions by transmission electron cryo-microscopy and determined the arrangement of the FP-tag on the surface of the virion. The fluorescent proteins are arranged icosahedrally on the virus surface in a stable manner that did not adversely affect receptor binding or fusion functions of E2 and E1, respectively. The delay in surface expression of the viral glycoproteins, as demonstrated by flow cytometry analysis, contributed to a 10-fold reduction in mCherry-E2 virus titer. There is a 1:1 ratio of mCherry to E2 incorporated into the virion, which leads to a strong fluorescence signal and thus facilitates single-particle tracking experiments. We used the FP-tagged virus for high-resolution live-cell imaging to study the spatial and temporal aspects of alphavirus assembly and budding from mammalian cells. These processes were further analyzed by thin section microscopy. The results demonstrate that SINV buds from the plasma membrane of infected cells and is dispersed into the surrounding media or spread to neighboring cells facilitated by its close association with filopodial extensions. PMID:26633461

  14. Single Particle Dynamic Imaging and Fe3+ Sensing with Bright Carbon Dots Derived from Bovine Serum Albumin Proteins

    NASA Astrophysics Data System (ADS)

    Yang, Qingxiu; Wei, Lin; Zheng, Xuanfang; Xiao, Lehui

    2015-12-01

    In this work, we demonstrated a convenient and green strategy for the synthesis of highly luminescent and water-soluble carbon dots (Cdots) by carbonizing carbon precursors, i.e., Bovine serum albumin (BSA) nanoparticles, in water solution. Without post surface modification, the as-synthesized Cdots exhibit fluorescence quantum yield (Q.Y.) as high as 34.8% and display superior colloidal stability not only in concentrated salt solutions (e.g. 2 M KCl) but also in a wide range of pH solutions. According to the FT-IR measurements, the Cdots contain many carboxyl groups, providing a versatile route for further chemical and biological functionalization. Through conjugation of Cdots with the transacting activator of transcription (TAT) peptide (a kind of cell penetration peptide (CPP)) derived from human immunodeficiency virus (HIV), it is possible to directly monitor the dynamic interactions of CPP with living cell membrane at single particle level. Furthermore, these Cdots also exhibit a dosage-dependent selectivity toward Fe3+ among other metal ions, including K+, Na+, Mg2+, Hg2+, Co2+, Cu2+, Pb2+ and Al3+. We believed that the Cdots prepared by this strategy would display promising applications in various areas, including analytical chemistry, nanomedicine, biochemistry and so on.

  15. Multishell Au/Ag/SiO2 nanorods with tunable optical properties as single particle orientation and rotational tracking probes

    DOE PAGESBeta

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

    2015-04-07

    In this study, three-layer core–shell plasmonic nanorods (Au/Ag/SiO2–NRs), consisting of a gold nanorod core, a thin silver shell, and a thin silica layer, were synthesized and used as optical imaging probes under a differential interference contrast microscope for single particle orientation and rotational tracking. The localized surface plasmon resonance modes were enhanced upon the addition of the silver shell, and the anisotropic optical properties of gold nanorods were maintained. The silica coating enables surface functionalization with silane coupling agents and provides enhanced stability and biocompatibility. Taking advantage of the longitudinal LSPR enhancement, the orientation and rotational information of the hybridmore » nanorods on synthetic lipid bilayers and on live cell membranes were obtained with millisecond temporal resolution using a scientific complementary metal-oxide-semiconductor camera. The results demonstrate that the as-synthesized hybrid nanorods are promising imaging probes with improved sensitivity and good biocompatibility for single plasmonic particle tracking experiments in biological systems.« less

  16. Single particle optical extinction and scattering allows real time quantitative characterization of drug payload and degradation of polymeric nanoparticles

    PubMed Central

    Potenza, M. A. C.; Sanvito, T.; Argentiere, S.; Cella, C.; Paroli, B.; Lenardi, C.; Milani, P.

    2015-01-01

    The behavior of nanoparticles in biological systems is determined by their dimensions, size distribution, shape, surface chemistry, density, drug loading and stability; the characterization of these parameters in realistic conditions and the possibility to follow their evolution in vitro and in vivo are, in most of the cases, far from the capabilities of the standard characterization technologies. Optical techniques such as dynamic light scattering (DLS) are, in principle, well suited for in line characterization of nanoparticle, however their fail in characterizing the evolution of nanoparticle in solution where change in particle dimension and density is present. Here we present an in-line optical technique based on single particle extinction and scattering (SPES) overcoming the limitations typical of DLS and allowing for the efficient characterization of nanoparticle polydispersity, index of refraction and degradation dynamics in solution. Using SPES, we characterized the evolution of PLGA nanoparticles with different structures and drug payloads in solution and we compared the results with DLS. Our results suggest that SPES could be used as a process analytical technology for pharmaceutical nanoparticle production. PMID:26667064

  17. Numerical simulation of thermal behavior of lithium-ion secondary batteries using the enhanced single particle model

    NASA Astrophysics Data System (ADS)

    Baba, Naoki; Yoshida, Hiroaki; Nagaoka, Makoto; Okuda, Chikaaki; Kawauchi, Shigehiro

    2014-04-01

    To understand the thermal behavior of lithium-ion secondary batteries, distributed information related to local heat generation across the entire electrode plane, which is caused by the electrochemical reaction that results from lithium-ion intercalation or deintercalation, is required. To accomplish this, we first developed an enhanced single particle (ESP) model for lithium-ion batteries that provides a cost effective, timely, and accurate method for estimating the local heat generation rates without excessive computation costs. This model accounts for all the physical processes, including the solution phase limitation. Next, a two-way electrochemical-thermal coupled simulation method was established. In this method, the three dimensional (3D) thermal solver is coupled with the quasi-3D porous electrode solver that is applied to the unrolled plane of spirally wound electrodes, which allows both thermal and electrochemical behaviors to be reproduced simultaneously at every computational time-step. The quasi-3D porous electrode solver implements the ESP model. This two-way coupled simulation method was applied to a thermal behavior analysis of 18650-type lithium-ion cells where it was found that temperature estimates of the electrode interior and on the cell can wall obtained via the ESP model were in good agreement with actual experimental measurements.

  18. Single particle optical extinction and scattering allows real time quantitative characterization of drug payload and degradation of polymeric nanoparticles

    NASA Astrophysics Data System (ADS)

    Potenza, M. A. C.; Sanvito, T.; Argentiere, S.; Cella, C.; Paroli, B.; Lenardi, C.; Milani, P.

    2015-12-01

    The behavior of nanoparticles in biological systems is determined by their dimensions, size distribution, shape, surface chemistry, density, drug loading and stability; the characterization of these parameters in realistic conditions and the possibility to follow their evolution in vitro and in vivo are, in most of the cases, far from the capabilities of the standard characterization technologies. Optical techniques such as dynamic light scattering (DLS) are, in principle, well suited for in line characterization of nanoparticle, however their fail in characterizing the evolution of nanoparticle in solution where change in particle dimension and density is present. Here we present an in-line optical technique based on single particle extinction and scattering (SPES) overcoming the limitations typical of DLS and allowing for the efficient characterization of nanoparticle polydispersity, index of refraction and degradation dynamics in solution. Using SPES, we characterized the evolution of PLGA nanoparticles with different structures and drug payloads in solution and we compared the results with DLS. Our results suggest that SPES could be used as a process analytical technology for pharmaceutical nanoparticle production.

  19. Determining transport efficiency for the purpose of counting and sizing nanoparticles via single particle inductively coupled plasma-mass spectrometry

    PubMed Central

    Pace, Heather E.; Rogers, Nicola J.; Jarolimek, Chad; Coleman, Victoria A.; Higgins, Christopher P.; Ranville, James F.

    2011-01-01

    Currently there are few ideal methods for the characterization of nanoparticles in complex, environmental samples, leading to significant gaps in toxicity and exposure assessments of nanomaterials. Single particle-inductively coupled plasma-mass spectrometry (spICP-MS) is an emerging technique that can both size and count metal-containing nanoparticles. A major benefit of the spICP-MS method is its ability to characterize nanoparticles at concentrations relevant to the environment. This paper presents a practical guide on how to count and size nanoparticles using spICP-MS. Different methods are investigated for measuring transport efficiency (i.e. nebulization efficiency), an important term in the spICP-MS calculations. In addition, an alternative protocol is provided for determining particle size that broadens the applicability of the technique to all types of inorganic nanoparticles. Initial comparison, using well-characterized, monodisperse silver nanoparticles, showed the importance of having an accurate transport efficiency value when determining particle number concentration and, if using the newly presented protocol, particle size. Ultimately, the goal of this paper is to provide improvements to nanometrology by further developing this technique for the characterization of metal-containing nanoparticles. PMID:22074486

  20. Investigation of refractory black carbon-containing particle morphologies using the single-particle soot photometer (SP2)

    SciTech Connect

    Sedlacek, III, Arthur J.; Lewis, Ernie R.; Onasch, Timothy B.; Lambe, Andrew T.; Davidovits, Paul

    2015-07-24

    An important source of uncertainty in radiative forcing by absorbing aerosol particles is the uncertainty in their morphologies (i.e., the location of the absorbing substance on/in the particles). To examine the effects of particle morphology on the response of an individual black carbon-containing particle in a Single-Particle Soot Photometer (SP2), a series of experiments was conducted to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate), and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermo-chemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources.

  1. Single Particle Dynamic Imaging and Fe3+ Sensing with Bright Carbon Dots Derived from Bovine Serum Albumin Proteins

    PubMed Central

    Yang, Qingxiu; Wei, Lin; Zheng, Xuanfang; Xiao, Lehui

    2015-01-01

    In this work, we demonstrated a convenient and green strategy for the synthesis of highly luminescent and water-soluble carbon dots (Cdots) by carbonizing carbon precursors, i.e., Bovine serum albumin (BSA) nanoparticles, in water solution. Without post surface modification, the as-synthesized Cdots exhibit fluorescence quantum yield (Q.Y.) as high as 34.8% and display superior colloidal stability not only in concentrated salt solutions (e.g. 2 M KCl) but also in a wide range of pH solutions. According to the FT-IR measurements, the Cdots contain many carboxyl groups, providing a versatile route for further chemical and biological functionalization. Through conjugation of Cdots with the transacting activator of transcription (TAT) peptide (a kind of cell penetration peptide (CPP)) derived from human immunodeficiency virus (HIV), it is possible to directly monitor the dynamic interactions of CPP with living cell membrane at single particle level. Furthermore, these Cdots also exhibit a dosage-dependent selectivity toward Fe3+ among other metal ions, including K+, Na+, Mg2+, Hg2+, Co2+, Cu2+, Pb2+ and Al3+. We believed that the Cdots prepared by this strategy would display promising applications in various areas, including analytical chemistry, nanomedicine, biochemistry and so on. PMID:26634992

  2. Single-particle imaging reveals intraflagellar transport-independent transport and accumulation of EB1 in Chlamydomonas flagella.

    PubMed

    Harris, J Aaron; Liu, Yi; Yang, Pinfen; Kner, Peter; Lechtreck, Karl F

    2016-01-15

    The microtubule (MT) plus-end tracking protein EB1 is present at the tips of cilia and flagella; end-binding protein 1 (EB1) remains at the tip during flagellar shortening and in the absence of intraflagellar transport (IFT), the predominant protein transport system in flagella. To investigate how EB1 accumulates at the flagellar tip, we used in vivo imaging of fluorescent protein-tagged EB1 (EB1-FP) in Chlamydomonas reinhardtii. After photobleaching, the EB1 signal at the flagellar tip recovered within minutes, indicating an exchange with unbleached EB1 entering the flagella from the cell body. EB1 moved independent of IFT trains, and EB1-FP recovery did not require the IFT pathway. Single-particle imaging showed that EB1-FP is highly mobile along the flagellar shaft and displays a markedly reduced mobility near the flagellar tip. Individual EB1-FP particles dwelled for several seconds near the flagellar tip, suggesting the presence of stable EB1 binding sites. In simulations, the two distinct phases of EB1 mobility are sufficient to explain its accumulation at the tip. We propose that proteins uniformly distributed throughout the cytoplasm like EB1 accumulate locally by diffusion and capture; IFT, in contrast, might be required to transport proteins against cellular concentration gradients into or out of cilia. PMID:26631555

  3. Investigation of refractory black carbon-containing particle morphologies using the single-particle soot photometer (SP2)

    DOE PAGESBeta

    Sedlacek, III, Arthur J.; Lewis, Ernie R.; Onasch, Timothy B.; Lambe, Andrew T.; Davidovits, Paul

    2015-07-24

    An important source of uncertainty in radiative forcing by absorbing aerosol particles is the uncertainty in their morphologies (i.e., the location of the absorbing substance on/in the particles). To examine the effects of particle morphology on the response of an individual black carbon-containing particle in a Single-Particle Soot Photometer (SP2), a series of experiments was conducted to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate),more » and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermo-chemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources.« less

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

    SciTech Connect

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

    2012-01-06

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

  5. Single-Particle Spectroscopic Study on Fluorescence Enhancement by Plasmon Coupled Gold Nanorod Dimers Assembled on DNA Origami.

    PubMed

    Zhang, Taishi; Gao, Nengyue; Li, Shuang; Lang, Matthew J; Xu, Qing-Hua

    2015-06-01

    Metal-enhanced fluorescence has attracted much attention due to its scientific importance and lots of potential applications. Plasmon coupled metal nanoparticles have been demonstrated to further improve the enhancement effects. Conventional studies of metal-enhanced fluorescence on the bulk systems are complicated by the ensemble average effects over many critical factors with large variations. Here, fluorescence enhancement of ATTO-655 by a plasmon coupled gold nanorod dimer fixed on a DNA origami nanobreadboard was studied on the single-particle level. A series of gold nanorod dimers with linear orientation and different gap distances ranging from 6.1 to 26.0 nm were investigated to explore the plasmon coupling effect on fluorescence enhancement. The results show that the dimer with the smallest gap (6.1 nm) gives the highest enhancement (470-fold), and the enhancement gradually decreases as the gap distance increases and eventually approaches that from a monomer (120-fold). This trend is consistent with the numerical calculation results. This study indicates that plasmon coupling in gold nanorod dimers offers further increased excitation efficiency to achieve large fluorescence enhancement. PMID:26266500

  6. Single Particle and PET-based Platform for Identifying Optimal Plasmonic Nano-Heaters for Photothermal Cancer Therapy.

    PubMed

    Jørgensen, Jesper Tranekjær; Norregaard, Kamilla; Tian, Pengfei; Bendix, Poul Martin; Kjaer, Andreas; Oddershede, Lene B

    2016-01-01

    Plasmonic nanoparticle-based photothermal cancer therapy is a promising new tool to inflict localized and irreversible damage to tumor tissue by hyperthermia, without harming surrounding healthy tissue. We developed a single particle and positron emission tomography (PET)-based platform to quantitatively correlate the heat generation of plasmonic nanoparticles with their potential as cancer killing agents. In vitro, the heat generation and absorption cross-section of single irradiated nanoparticles were quantified using a temperature sensitive lipid-based assay and compared to their theoretically predicted photo-absorption. In vivo, the heat generation of irradiated nanoparticles was evaluated in human tumor xenografts in mice using 2-deoxy-2-[F-18]fluoro-D-glucose ((18)F-FDG) PET imaging. To validate the use of this platform, we quantified the photothermal efficiency of near infrared resonant silica-gold nanoshells (AuNSs) and benchmarked this against the heating of colloidal spherical, solid gold nanoparticles (AuNPs). As expected, both in vitro and in vivo the heat generation of the resonant AuNSs performed superior compared to the non-resonant AuNPs. Furthermore, the results showed that PET imaging could be reliably used to monitor early treatment response of photothermal treatment. This multidisciplinary approach provides a much needed platform to benchmark the emerging plethora of novel plasmonic nanoparticles for their potential for photothermal cancer therapy. PMID:27481537

  7. Single particle ICP-MS characterization of titanium dioxide, silver, and gold nanoparticles during drinking water treatment.

    PubMed

    Donovan, Ariel R; Adams, Craig D; Ma, Yinfa; Stephan, Chady; Eichholz, Todd; Shi, Honglan

    2016-02-01

    One of the most direct means for human exposure to nanoparticles (NPs) released into the environment is drinking water. Therefore, it is critical to understand the occurrence and fate of NPs in drinking water systems. The objectives of this study were to develop rapid and reliable analytical methods and apply them to investigate the fate and transportation of NPs during drinking water treatments. Rapid single particle ICP-MS (SP-ICP-MS) methods were developed to characterize and quantify titanium-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution, and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. The selected NPs were nearly completely (97 ± 3%) removed after lime softening and alum coagulation/activated carbon adsorption treatments. Additionally, source and drinking waters from three large drinking water treatment facilities utilizing similar treatments with the simulation test were collected and analyzed by the SP-ICP-MS methods. Ti-containing particles and dissolved Ti were present in the river water samples, but Ag and Au were not present. Treatments used at each drinking water treatment facility effectively removed over 93% of the Ti-containing particles and dissolved Ti from the source water. PMID:26347937

  8. Nanoscopic substructures of raft-mimetic liquid-ordered membrane domains revealed by high-speed single-particle tracking

    PubMed Central

    Wu, Hsiao-Mei; Lin, Ying-Hsiu; Yen, Tzu-Chi; Hsieh, Chia-Lung

    2016-01-01

    Lipid rafts are membrane nanodomains that facilitate important cell functions. Despite recent advances in identifying the biological significance of rafts, nature and regulation mechanism of rafts are largely unknown due to the difficulty of resolving dynamic molecular interaction of rafts at the nanoscale. Here, we investigate organization and single-molecule dynamics of rafts by monitoring lateral diffusion of single molecules in raft-containing reconstituted membranes supported on mica substrates. Using high-speed interferometric scattering (iSCAT) optical microscopy and small gold nanoparticles as labels, motion of single lipids is recorded via single-particle tracking (SPT) with nanometer spatial precision and microsecond temporal resolution. Processes of single molecules partitioning into and escaping from the raft-mimetic liquid-ordered (Lo) domains are directly visualized in a continuous manner with unprecedented clarity. Importantly, we observe subdiffusion of saturated lipids in the Lo domain in microsecond timescale, indicating the nanoscopic heterogeneous molecular arrangement of the Lo domain. Further analysis of the diffusion trajectory shows the presence of nano-subdomains of the Lo phase, as small as 10 nm, which transiently trap the lipids. Our results provide the first experimental evidence of non-uniform molecular organization of the Lo phase, giving a new view of how rafts recruit and confine molecules in cell membranes. PMID:26861908

  9. Nanoscopic substructures of raft-mimetic liquid-ordered membrane domains revealed by high-speed single-particle tracking

    NASA Astrophysics Data System (ADS)

    Wu, Hsiao-Mei; Lin, Ying-Hsiu; Yen, Tzu-Chi; Hsieh, Chia-Lung

    2016-02-01

    Lipid rafts are membrane nanodomains that facilitate important cell functions. Despite recent advances in identifying the biological significance of rafts, nature and regulation mechanism of rafts are largely unknown due to the difficulty of resolving dynamic molecular interaction of rafts at the nanoscale. Here, we investigate organization and single-molecule dynamics of rafts by monitoring lateral diffusion of single molecules in raft-containing reconstituted membranes supported on mica substrates. Using high-speed interferometric scattering (iSCAT) optical microscopy and small gold nanoparticles as labels, motion of single lipids is recorded via single-particle tracking (SPT) with nanometer spatial precision and microsecond temporal resolution. Processes of single molecules partitioning into and escaping from the raft-mimetic liquid-ordered (Lo) domains are directly visualized in a continuous manner with unprecedented clarity. Importantly, we observe subdiffusion of saturated lipids in the Lo domain in microsecond timescale, indicating the nanoscopic heterogeneous molecular arrangement of the Lo domain. Further analysis of the diffusion trajectory shows the presence of nano-subdomains of the Lo phase, as small as 10 nm, which transiently trap the lipids. Our results provide the first experimental evidence of non-uniform molecular organization of the Lo phase, giving a new view of how rafts recruit and confine molecules in cell membranes.

  10. Kraus representation of a damped harmonic oscillator and its application

    SciTech Connect

    Liu Yuxi; Oezdemir, Sahin K.; Miranowicz, Adam; Imoto, Nobuyuki

    2004-10-01

    By definition, the Kraus representation of a harmonic oscillator suffering from the environment effect, modeled as the amplitude damping or the phase damping, is directly given by a simple operator algebra solution. As examples and applications, we first give a Kraus representation of a single qubit whose computational basis states are defined as bosonic vacuum and single particle number states. We further discuss the environment effect on qubits whose computational basis states are defined as the bosonic odd and even coherent states. The environment effects on entangled qubits defined by two different kinds of computational basis are compared with the use of fidelity.

  11. Characteristics of atmospheric single particles during haze periods in a typical urban area of Beijing: A case study in October, 2014.

    PubMed

    Liu, Lang; Wang, Yanli; Du, Shiyong; Zhang, Wenjie; Hou, Lujian; Vedal, Sverre; Han, Bin; Yang, Wen; Chen, Mindong; Bai, Zhipeng

    2016-02-01

    To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer (SPAMS) was deployed to measure the changes of single particle species and sizes during October of 2014, in Beijing. A total of 2,871,431 particles with both positive and negative spectra were collected and characterized in combination with the adaptive resonance theory neural network algorithm (ART-2a). Eight types of particles were classified: dust particles (dust, 8.1%), elemental carbon (EC, 29.0%), organic carbon (OC, 18.0%), EC and OC combined particles (ECOC, 9.5%), Na-K containing particles (NaK, 7.9%), K-containing particles (K, 21.8%), organic nitrogen and potassium containing particles (KCN, 2.3%), and metal-containing particles (metal, 3.6%). Three haze pollution events (P1, P2, P3) and one clean period (clean) were analyzed, based on the mass and number concentration of PM2.5 and the back trajectory results from the hybrid single particle Lagrangian integrated trajectory model (Hysplit-4 model). Results showed that EC, OC and K were the major components of single particles during the three haze pollution periods, which showed clearly increased ratios compared with those in the clean period. Results from the mixing state of secondary species of different types of particles showed that sulfate and nitrate were more readily mixed with carbon-containing particles during haze pollution episodes than in clean periods. PMID:26969554

  12. Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

    EPA Science Inventory

    Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

  13. Oscillator detector

    SciTech Connect

    Potter, B.M.

    1980-05-13

    An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

  14. Grid oscillators

    NASA Technical Reports Server (NTRS)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  15. Single particles measured by a light scattering module coupled to a time-of-flight aerosol mass spectrometer onboard the NOAA P-3 aircraft during SENEX

    NASA Astrophysics Data System (ADS)

    Liao, J.; Middlebrook, A. M.; Welti, A.; Sueper, D.; Murphy, D. M.

    2014-12-01

    Single particles in the eastern US were characterized by a light scattering module coupled to a time-of-flight aerosol mass spectrometer (LS-ToF-AMS) onboard the NOAA P-3 aircraft during the Southeastern Nexus (SENEX) campaign. Single particle data were collected for 30 seconds every 5 minutes. Aerosols larger than 200-300 nm in vacuum aerodynamic diameter can be optically detected by the 405 nm crystal laser and trigger the saving of single particle mass spectra. The measured single particles are internally-mixed as expected. The single particles were classified as prompt, delayed, and null based on the chemical ion signal arrival time difference between prediction from the light scattering signal and measurement by mass spectrometer and the presence or absence of a mass spectrum. On average the number fraction of particles detected as prompt, delayed, and null (no spectrum) is about 30%, 10%, and 60%. The number fraction of these three particle types varied with aerosol size, chemical composition and the investigation region and will be discussed in detail. For example, the number fraction of prompt particles was significantly higher for the flight to the Pennsylvania natural gas shale region on July 6, 2013, which is probably related to the chemical composition (more acidic) and phase of the ambient particles. These particle types and detection efficiency are related to the bouncing effect on the vaporizer and may provide insight into the non-unit AMS collection efficiency. Moreover, most of the particles larger than 800 nm in vacuum aerodynamic diameter sized with the traditional AMS PToF mode are delayed particles and their mass spectral signals appear to be affected by this process.

  16. Foucault on the case: the pastoral and juridical foundation of medical power.

    PubMed

    Tierney, Thomas F

    2004-01-01

    This paper employs Foucault's concept of "governmentality" to examine critically the efforts by medical humanists to reform the medical case. I argue that these reform efforts contribute to the individualizing dimensions of medical power through the development of a "pastoral" technique that medicine has taken over from religious authority. Clinical experiences at this NEH Institute also revealed a juridical dimension of the medical case that treats a patient's statements as suspect and in need of corroboration by evidence provided by the patient's body. The combination of these pastoral and juridical dimensions of the case contributes to the normalizing power of modern medicine, and medical humanists need to be aware of their own contribution to this form of power as they reform the case. PMID:15666081

  17. Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

    NASA Astrophysics Data System (ADS)

    Xu, Lingling; Chen, Jinsheng

    2016-04-01

    Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

  18. Black carbon aerosol characterization in a coastal city in South China using a single particle soot photometer

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Feng; Sun, Tian-Le; Zeng, Li-Wu; Yu, Guang-He; Luan, Sheng-Ji

    2012-05-01

    Black carbon (BC) is the dominant light-absorbing aerosol component in the atmosphere and plays an important role in atmospheric pollution and climate change. The light-absorbing properties of BC rely on particle size, shape, composition, as well as the BC mixing state with other aerosol components, thus more thorough exploration of BC aerosol characteristics is critical in understanding its atmospheric sources and effects. In this study, a newly-developed Single Particle Soot Photometer (SP2) was deployed in Shenzhen, China, for continuous BC measurements to obtain the important information about size distribution and mixing state of BC under severe air pollution conditions of China. The mean BC mass concentrations were found to be 6.0 and 4.1 μg m-3 at an urban site (UT) in the fall and winter, respectively, while it is much lower (2.6 μg m-3) at a rural site (BG) in the fall. The mass size distributions of BC in volume equivalent diameter (VED) at the three sites showed a similar lognormal pattern, with the peak diameter at BG (222 nm) slightly larger than at the UT (210 nm) site. As to mixing state, the average percentage of internally mixed BC at the UT site was detected to be 40% and 46% in the fall and winter, respectively, while that at the BG site in the fall was only a slightly higher (47%), which implies that fresh local fossil fuel combustions were still significant at this rural site. The analysis of extremely high BC concentrations (>20 μg m-3) at UT indicates that they were a complex of comparable contributions from both local fresh emissions and regional transport under unfavorable meteorology. Other characteristics of BC aerosol and their influencing factors in Shenzhen were also discussed.

  19. Imaging the fine-scale structure of the cellular actin cytoskeleton by Single Particle Tracking and Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Mustata, Gina-Mirela

    It has been proposed that diffusion in the plasma membrane of eukaryotic cells it is compartmentalized due to the interaction with the underlying actin-based membrane skeleton that comes into close proximity to the lipid bilayer. The cytoskeleton is a dynamic structure that maintains cell shape, enables cell motion, and plays important roles in both intra-cellular transport and cellular division. We show here the evidence of plasma membrane compartmentalization using Single Particle Tracking (SPT) and Atomic Force Microscopy (AFM) imaging. SPT of Quantum dot labeled lipid in the plasma membrane of live normal rat kidney cells show compartments ranging from 325 nm to 391 nm depending on the sampling time. Using AFM imaging of live NRK cell in the presence of phalloidin, the membrane compartmentalization it is visible with the average size of the compartments of 325 +/- 10 nm (the main peak is centered at 260 nm). Further, the underlying membrane skeleton in fixed cells was directly imaged after partial removal of the plasma membrane to reveal size of the membrane skeleton meshwork of 339 +/- 10 nm. A new method of measuring the characteristics of the actin meshwork was proposed. Probing the local compliance of the plasma membrane through the deflection of a soft AFM cantilever we can expect that the stiffness of the membrane will be higher at locations directly above a cortical actin. This new method provided information about the structure of the skeletal meshwork of neuronal cell body predicting an average compartment size of about 132 nm. This was confirmed through SPT of QD-lipid incorporated into the neuronal cell membrane.

  20. Extraction and analysis of silver and gold nanoparticles from biological tissues using single particle inductively coupled plasma mass spectrometry.

    PubMed

    Gray, Evan P; Coleman, Jessica G; Bednar, Anthony J; Kennedy, Alan J; Ranville, James F; Higgins, Christopher P

    2013-12-17

    Expanded use of engineered nanoparticles (ENPs) in consumer products increases the potential for environmental release and unintended biological exposures. As a result, measurement techniques are needed to accurately quantify ENP size, mass, and particle number distributions in biological matrices. This work combines single particle inductively coupled plasma mass spectrometry (spICPMS) with tissue extraction to quantify and characterize metallic ENPs in environmentally relevant biological tissues for the first time. ENPs were extracted from tissues via alkaline digestion using tetramethylammonium hydroxide (TMAH). Method development was performed using ground beef and was verified in Daphnia magna and Lumbriculus variegatus . ENPs investigated include 100 and 60 nm Au and Ag stabilized by polyvynylpyrrolidone (PVP). Mass- and number-based recovery of spiked Au and Ag ENPs was high (83-121%) from all tissues tested. Additional experiments suggested ENP mixtures (60 and 100 nm Ag ENPs) could be extracted and quantitatively analyzed. Biological exposures were also conducted to verify the applicability of the method for aquatic organisms. Size distributions and particle number concentrations were determined for ENPs extracted from D. magna exposed to 98 μg/L 100 nm Au and 4.8 μg/L 100 nm Ag ENPs. The D. magna nanoparticulate body burden for Au ENP uptake was 613 ± 230 μg/kgww, while the measured nanoparticulate body burden for D. magna exposed to Ag ENPs was 59 ± 52 μg/kgww. Notably, the particle size distributions determined from D. magna tissues suggested minimal shifts in the size distributions of ENPs accumulated, as compared to the exposure media. PMID:24218983