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Sample records for single-particle foucault oscillator

  1. Single-particle motional oscillator powered by laser.

    PubMed

    Kaplan, A E

    2009-06-08

    An ion, atom, molecule or macro-particle in a trap can exhibit large motional oscillations due to the Doppler-affected radiation pressure by a laser, blue-detuned from an absorption line of a particle. This oscillator can be nearly thresholdless, but under certain conditions it may exhibit huge hysteretic excitation. Feasible applications include a "Foucault pendulum" in a trap, a rotation sensor, single atom spectroscopy, isotope separation, etc.

  2. 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.

  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. 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,

  5. The anisosphere as a new tool for interpreting Foucault pendulum experiments. Part I: harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Verreault, René

    2017-08-01

    In an attempt to explain the tendency of Foucault pendula to develop elliptical orbits, Kamerlingh Onnes derived equations of motion that suggest the use of great circles on a spherical surface as a graphical illustration for an anisotropic bi-dimensional harmonic oscillator, although he did not himself exploit the idea any further. The concept of anisosphere is introduced in this work as a new means of interpreting pendulum motion. It can be generalized to the case of any two-dimensional (2-D) oscillating system, linear or nonlinear, including the case where coupling between the 2 degrees of freedom is present. Earlier pendulum experiments in the literature are revisited and reanalyzed as a test for the anisosphere approach. While that graphical method can be applied to strongly nonlinear cases with great simplicity, this part I is illustrated through a revisit of Kamerlingh Onnes' dissertation, where a high performance pendulum skillfully emulates a 2-D harmonic oscillator. Anisotropy due to damping is also described. A novel experiment strategy based on the anisosphere approach is proposed. Finally, recent original results with a long pendulum using an electronic recording alidade are presented. A gain in precision over traditional methods by 2-3 orders of magnitude is achieved.

  6. 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.

  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. {Lambda} single particle energies

    SciTech Connect

    Usmani, Q.N.; Bodmer, A.R. |

    1999-11-01

    The {Lambda} single-particle energies B{sub {Lambda}} of hypernuclei (HN) are calculated microscopically using the Fermi hypernetted chain method to obtain for our {Lambda}N and {Lambda}NN potentials the {Lambda} binding D({rho}) to nuclear matter, and the effective mass m{sub {Lambda}}{sup {asterisk}}({rho}) at densities {rho}{le}{rho}{sub 0} ({rho}{sub 0} is normal nuclear density), and also the corresponding effective {Lambda}N and {Lambda}NN potentials. The {Lambda} core-nucleus potential U{sub {Lambda}}(r) is obtained by suitably folding these into the core density. The Schr{umlt o}dinger equation for U{sub {Lambda}} and m{sub {Lambda}}{sup {asterisk}} is solved for B{sub {Lambda}}. The fringing field (FF) due to the finite range of the effective potentials is theoretically required. We use a dispersive {Lambda}NN potential but also include a phenomenological {rho} dependence allowing for less repulsion for {rho}{lt}{rho}{sub 0}, i.e., in the surface. The best fits to the data with a FF give a large {rho} dependence, equivalent to an {ital A} dependent strength consistent with variational calculations of {sub {Lambda}}{sup 5}He, indicating an effective {Lambda}NN dispersive potential increasingly repulsive with {ital A} whose likely interpretation is in terms of dispersive plus two-pion-exchange {Lambda}NN potentials. The well depth is 29{plus_minus}1&hthinsp;MeV. The {Lambda}N space-exchange fraction corresponds to m{sub {Lambda}}{sup {asterisk}}({rho}){approx}0.75{endash}0.80 and a ratio of {ital p}- to {ital s}-state potentials of {approx}0.5{plus_minus}0.1. Charge symmetry breaking (CSB) is significant for heavy HN with a large neutron excess; with a FF the strength agrees with that obtained from the A=4&hthinsp;HN. The fits without FF are excellent but inconsistent with the requirement for a FF, with {sub {Lambda}}{sup 5}He, and also with the CSB sign for A=4. {copyright} {ital 1999} {ital The American Physical Society}

  10. A single particle energies

    SciTech Connect

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

    1993-09-01

    We consider the binding energies of {Lambda} hypernuclei (HN), in particular the single-particle (s.p.) energy data, which have been obtained for a wide range of HN with mass numbers A {le} 89 and for orbital angular momenta {ell}{sub {Lambda}} {le} 4. We briefly review some of the relevant properties of A hypernuclei. These are nuclei {sub {Lambda}}{sup A}Z with baryon number A in which a single {Lambda} hyperon (baryon number = 1) is bound to an ordinary nucleus {sup A}Z consisting of A - 1 nucleons = Z protons + N neutrons. The {Lambda} hyperon is neutral, has spin 1/2, strangeness S = {minus}1, isospin I = O and a mass M{sub {Lambda}} = 1116 MeV/c{sup 2}. Although the {Lambda} interacts with a nucleon, its interaction is only about half as strong as that between two nucleons, and thus very roughly V{sub {Lambda}N} {approx} 0.5 V{sub NN}. As a result, the two-body {Lambda}N system is unbound, and the lightest bound HN is the three-body hypertriton {sub {Lambda}}{sup 3}H in which the {Lambda} is bound to a deuteron with the {Lambda}-d separation energy being only {approx} 0.1 MeV corresponding to an exponential tail of radius {approx} 15 fm! In strong interactions the strangeness S is of course conserved, and the {Lambda} is distinct from the nucleons. In a HN strangeness changes only in the weak decays of the {Lambda} which can decay either via ``free`` pionic decay {Lambda} {yields} N + {pi} or via induced decay {Lambda} + N {yields} N + N which is only possible in the presence of nucleons. Because of the small energy release the pionic decay is strongly suppressed in all but the lightest HN and the induced decay dominates. However, the weak decay lifetime {approx} 10{sup {minus}10}s is in fact close to the lifetime of a free {Lambda}. Since this is much longer than the strong interaction time {approx} 10{sup {minus}22}s we can ignore the weak interactions when considering the binding of HN, just as for ordinary nuclei.

  11. 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)

  12. 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)

  13. 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.

  14. {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.

  15. [Foucault's relevance for psychology].

    PubMed

    Pastor, Juan

    2009-11-01

    In this article, we will attempt to address one of the most outstanding and influential thinkers of the past century: Michel Foucault, Philosopher, Psychologist, and above all (university) Professor. Michel Foucault is certainly versatile: Historian (of madness, clinical practice, imprisonment and sexuality), Archaeologist (of knowledge), Analyst (of discourse and power relations), Psychologist (genealogy of subjectivity) and Philosopher (of power and the subject). With this article, we eventually expect to offer some clues to be able to use the work of Michel Foucault for the problematization of Psychology.

  16. Who can resist Foucault?

    PubMed

    Bleakley, Alan; Bligh, John

    2009-08-01

    Michel Foucault's analysis of "the birth of the clinic" describes the genesis of a unified discourse that, in retrospect, has shaped western medicine for two centuries. However, in looking prospectively toward a 21st century medicine, Foucault's analysis is necessary but not sufficient. To better critically address medicine and medical education in the era of simulation, we could draw on frameworks developed by futurists such as Jean Baudrillard. Foucault's analysis does not account for contemporary, complex developments of the clinical gaze as the gaze is distributed across practitioners in increasing use of sophisticated, representational diagnostic imaging. Further, Foucault's antihumanist rhetoric sometimes strays into the antihumane, and this is disturbing for those who support the development of patient-centered medicine. Yet we are increasingly teaching aspects of medicine, such as communication, in simulated learning environments in which complex reality is absent, perhaps inadvertently creating an "inhumanity" in medical education.

  17. 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.

  18. Single-particle levels in cluster potentials

    NASA Astrophysics Data System (ADS)

    Della Rocca, V.; Bijker, R.; Iachello, F.

    2017-10-01

    We calculate single-particle levels in potentials with Z2 (dumbbell), D3h (triangle) and Td (tetrahedral) symmetry, appropriate to the α-cluster structure of 8Be, 12C and 16O respectively. We suggest that these can be used to study, within the framework of a cluster shell model (CSM), kα + x nucleon structures, with k = 2 , 3 , 4 and x = 1 , 2 , …, in particular the single particle (x = 1) structures 9Be, 9B; 13C, 13N; 17O, 17F.

  19. Single particle diversity and mixing state measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Riemer, N.; Wenger, J. C.; Murphy, M.; West, M.; Poulain, L.; Wiedensohler, A.; O'Connor, I. P.; McGillicuddy, E.; Sodeau, J. R.; Evans, G. J.

    2014-02-01

    A newly developed framework for quantifying aerosol particle diversity and mixing state based on information-theoretic entropy is applied for the first time to single particle mass spectrometry field data. Single particle mass fraction estimates for black carbon, organic aerosol, ammonium, nitrate and sulphate, derived using single particle mass spectrometer, aerosol mass spectrometer and multi-angle absorption photometer measurements are used to calculate single particle species diversity (Di). The average single particle species diversity (Dα) is then related to the species diversity of the bulk population (Dγ) to derive a mixing state index value (χ) at hourly resolution. The mixing state index is a single parameter representation of how internally/externally mixed a particle population is at a given time. The index describes a continuum, with values of 0% and 100% representing fully external and internal mixing, respectively. This framework was applied to data collected as part of the MEGAPOLI winter campaign in Paris, France 2010. Di values are low (∼2) for fresh traffic and woodburning particles that contain high mass fractions of black carbon and organic aerosol but low mass fractions of inorganic ions. Conversely, Di values are higher (∼4) for aged carbonaceous particles containing similar mass fractions of black carbon, organic aerosol, ammonium, nitrate and sulphate. Aerosol in Paris is estimated to be 59% internally mixed in the size range 150-1067 nm, and mixing state is dependent both upon time of day and air mass origin. Daytime primary emissions associated with vehicular traffic and woodburning result in low χ values, while enhanced condensation of ammonium nitrate on existing particles at night leads to higher χ values. Advection of particles from continental Europe containing ammonium, nitrate and sulphate leads to increases in Dα, Dγ and χ. The mixing state index represents a useful metric by which to compare and contrast ambient

  20. Single particle diversity and mixing state measurements

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Riemer, N.; Wenger, J. C.; Murphy, M.; West, M.; Poulain, L.; Wiedensohler, A.; O'Connor, I. P.; McGillicuddy, E.; Sodeau, J. R.; Evans, G. J.

    2014-06-01

    A newly developed framework for quantifying aerosol particle diversity and mixing state based on information-theoretic entropy is applied for the first time to single particle mass spectrometry field data. Single particle mass fraction estimates for black carbon, organic aerosol, ammonium, nitrate and sulfate, derived using single particle mass spectrometer, aerosol mass spectrometer and multi-angle absorption photometer measurements are used to calculate single particle species diversity (Di). The average single particle species diversity (Dα) is then related to the species diversity of the bulk population (Dγ) to derive a mixing state index value (χ) at hourly resolution. The mixing state index is a single parameter representation of how internally/externally mixed a particle population is at a given time. The index describes a continuum, with values of 0 and 100% representing fully external and internal mixing, respectively. This framework was applied to data collected as part of the MEGAPOLI winter campaign in Paris, France, 2010. Di values are low (~ 2) for fresh traffic and wood-burning particles that contain high mass fractions of black carbon and organic aerosol but low mass fractions of inorganic ions. Conversely, Di values are higher (~ 4) for aged carbonaceous particles containing similar mass fractions of black carbon, organic aerosol, ammonium, nitrate and sulfate. Aerosol in Paris is estimated to be 59% internally mixed in the size range 150-1067 nm, and mixing state is dependent both upon time of day and air mass origin. Daytime primary emissions associated with vehicular traffic and wood-burning result in low χ values, while enhanced condensation of ammonium nitrate on existing particles at night leads to higher χ values. Advection of particles from continental Europe containing ammonium, nitrate and sulfate leads to increases in Dα, Dγ and χ. The mixing state index represents a useful metric by which to compare and contrast ambient particle

  1. Single-particle states in transcurium nuclei.

    SciTech Connect

    Ahmad, I.

    1999-09-30

    Identification of single-particle states in the heaviest known nuclei is important because their energies can be used to test the single-particle potential in these high-Z elements. These states can be identified by studying the decay schemes of very heavy odd-mass nuclides. For neutrons, the heaviest odd-mass nuclide available in milliCurie quantities is the 20-h {sup 255}Fm and for protons the heaviest nuclide available is the 20-d {sup 253}Es. These two isotopes were obtained from the Transplutonium Element Production Program at Oak Ridge and their spectra were measured with high-resolution germanium spectrometers. From the results of these measurements we have identified states in {sup 251}Cf and {sup 249}Bk up to 1 MeV excitation energy.

  2. Single particle sources and quantum heat fluctuations

    NASA Astrophysics Data System (ADS)

    Battista, F.

    2014-10-01

    The miniaturisation of electronic devices has been a well-known trend in engineering over almost 50 years. The technological advancement in the field can now provide an astonishing control of charge transport in mesoscopic structures. Single particle pumping, namely the control in time and space of the flow of an arbitrarily small number of electrons or holes, has been realised in various kind of structure with, in some cases, very high accuracies. The first half of the manuscript provides a brief overview of different experimental realisations of single particle sources. Though these devices allow to minimise charge fluctuations in the charge current, because of Heisenberg's uncertainty principle, the emitted particles are characterised by energy fluctuations. The consequences of it are of great relevance and presented in the second part of the paper.

  3. 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.

  4. 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.

  5. 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.

  6. A new single-particle basis for nuclear many-body calculations

    NASA Astrophysics Data System (ADS)

    Puddu, G.

    2017-10-01

    Predominantly, harmonic oscillator single-particle wave functions are the preferred choice for a basis in ab initio nuclear many-body calculations. These wave-functions, although very convenient in order to evaluate the matrix elements of the interaction in the laboratory frame, have too fast a fall-off at large distances. In the past, as an alternative to the harmonic oscillator, other single-particle wave functions have been proposed. In this work, we propose a new single-particle basis, directly linked to nucleon–nucleon interaction. This new basis is orthonormal and complete, has the proper asymptotic behavior at large distances and does not contain the continuum which would pose severe convergence problems in nuclear many body calculations. We consider the newly proposed NNLO-opt nucleon–nucleon interaction, without any renormalization. We show that, unlike other bases, this single-particle representation has a computational cost similar to the harmonic oscillator basis with the same space truncation and it gives lower energies for 6He and 6Li.

  7. Single-particle study of protein assembly

    NASA Astrophysics Data System (ADS)

    Kiang, Ching-Hwa

    2001-10-01

    A study of protein assembly in solution with single-particle imaging and reconstruction techniques using cryoelectron microscopy is reported. The human glutamine synthetase enzyme, important in brain metabolism, and previously assumed to be assembled into a homogeneous quaternary structure, is found to be heterogeneous, with three oligomeric states that co-exist at room temperature. This result corrects an old structural and kinetic model determined by ensemble averaging techniques that assumed a homogeneous system. Unexpectedly fast protein dissociation kinetics results from a stabilized transition state.

  8. Hydrodynamic trap for single particles and cells

    PubMed Central

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

    2010-01-01

    Trapping and manipulation of microscale and nanoscale particles is demonstrated using the sole action of hydrodynamic forces. We developed an automated particle trap based on a stagnation point flow generated in a microfluidic device. The hydrodynamic trap enables confinement and manipulation of single particles in low viscosity (1–10 cP) aqueous solution. Using this method, we trapped microscale and nanoscale particles (100 nm–15 μm) for long time scales (minutes to hours). We demonstrate particle confinement to within 1 μm of the trap center, corresponding to a trap stiffness of ∼10−5–10−4 pN∕nm. PMID:20585593

  9. 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.

  10. 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.

  11. Signaling with a single-particle system

    NASA Astrophysics Data System (ADS)

    Jensen, Raymond W.

    2009-03-01

    In this article, an argument is presented for the possibility of a device which permits transmission of signals faster than the speed of light (FTLC), even retro-causally. The method relies on sending digital information to a receiver through the appearance and disappearance of an interference pattern. The purpose here is not to present a device which is practical for FTLC. It is to circumvent the myth that FTLC will not work with correlated systems of particles, because a coincidence circuit is needed to see the interference patterns. Thus, the argument is restricted to single-particle systems.

  12. Nanoscale three-dimensional single particle tracking

    NASA Astrophysics Data System (ADS)

    Dupont, Aurélie; Lamb, Don C.

    2011-11-01

    Single particle tracking (SPT) in biological systems is a quickly growing field. Many new technologies are being developed providing new tracking capabilities, which also lead to higher demands and expectations for SPT. Following a single biomolecule as it performs its function provides quantitative mechanistic information that cannot be obtained in classical ensemble methods. From the 3D trajectory, information is available over the diffusional behavior of the particle and precise position information can also be used to elucidate interactions of the tracked particle with its surroundings. Thus, three-dimensional (3D) SPT is a very valuable tool for investigating cellular processes. This review presents recent progress in 3D SPT, from image-based techniques toward more sophisticated feedback approaches. We focus mainly on the feedback technique known as orbital tracking. We present here a modified version of the original orbital tracking in which the intensities from two z-planes are simultaneously measured allowing a concomitant wide-field imaging. The system can track single particles with a precision down to 5 nm in the x-y plane and 7 nm in the axial direction. The capabilities of the system are demonstrated using single virus tracing to follow the infection pathway of Prototype Foamy Virus in living cells.Single particle tracking (SPT) in biological systems is a quickly growing field. Many new technologies are being developed providing new tracking capabilities, which also lead to higher demands and expectations for SPT. Following a single biomolecule as it performs its function provides quantitative mechanistic information that cannot be obtained in classical ensemble methods. From the 3D trajectory, information is available over the diffusional behavior of the particle and precise position information can also be used to elucidate interactions of the tracked particle with its surroundings. Thus, three-dimensional (3D) SPT is a very valuable tool for

  13. 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.

  14. 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

  15. 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.

  16. [Plato psychiatrist, Foucault platonic].

    PubMed

    Mathov, Nicolás

    2016-05-01

    This work explores the links between the concepts of "soul", "law" and "word" in Plato's work, in order to highlight the importance and the centrality of the philosophical-therapeutic dimension in the Greek philosopher's thought. In that way, this work pretends to show that "contemporary" problems usually discussed within "Human Sciences" in general, and Psychiatry in particular, should confront their knowledge with Plato's work, mainly due to the profound influence his ideas have had in our Greco-Christian culture. In that sense, and with that objective, this work also explores Michel Foucault's lucid and controversial interpretation of Plato.

  17. Anomalous Diffusion of Single Particles in Cytoplasm

    PubMed Central

    Regner, Benjamin M.; Vučinić, Dejan; Domnisoru, Cristina; Bartol, Thomas M.; Hetzer, Martin W.; Tartakovsky, Daniel M.; Sejnowski, Terrence J.

    2013-01-01

    The crowded intracellular environment poses a formidable challenge to experimental and theoretical analyses of intracellular transport mechanisms. Our measurements of single-particle trajectories in cytoplasm and their random-walk interpretations elucidate two of these mechanisms: molecular diffusion in crowded environments and cytoskeletal transport along microtubules. We employed acousto-optic deflector microscopy to map out the three-dimensional trajectories of microspheres migrating in the cytosolic fraction of a cellular extract. Classical Brownian motion (BM), continuous time random walk, and fractional BM were alternatively used to represent these trajectories. The comparison of the experimental and numerical data demonstrates that cytoskeletal transport along microtubules and diffusion in the cytosolic fraction exhibit anomalous (nonFickian) behavior and posses statistically distinct signatures. Among the three random-walk models used, continuous time random walk provides the best representation of diffusion, whereas microtubular transport is accurately modeled with fractional BM. PMID:23601312

  18. Single particle raster image analysis of diffusion.

    PubMed

    Longfils, M; Schuster, E; Lorén, N; Särkkä, A; Rudemo, M

    2017-04-01

    As a complement to the standard RICS method of analysing Raster Image Correlation Spectroscopy images with estimation of the image correlation function, we introduce the method SPRIA, Single Particle Raster Image Analysis. Here, we start by identifying individual particles and estimate the diffusion coefficient for each particle by a maximum likelihood method. Averaging over the particles gives a diffusion coefficient estimate for the whole image. In examples both with simulated and experimental data, we show that the new method gives accurate estimates. It also gives directly standard error estimates. The method should be possible to extend to study heterogeneous materials and systems of particles with varying diffusion coefficient, as demonstrated in a simple simulation example. A requirement for applying the SPRIA method is that the particle concentration is low enough so that we can identify the individual particles. We also describe a bootstrap method for estimating the standard error of standard RICS.

  19. Single Particle Analysis of Ice Forming Aerosols

    NASA Astrophysics Data System (ADS)

    Cziczo, Daniel J.; Kulkarni, Gourihar; Pratt, Kerri; Pekour, Mikahil; Hallar, Gannet; McCubbin, Ian

    2010-05-01

    During January and February of 2010 ice forming aerosol particles were analyzed at Storm Peak Laboratory in north-central Colorado in the USA. Atmospheric particles were acquired through an isokinetic inlet during periods when free-tropospheric conditions with minimal local influence existed. The particles were then subject to low temperature and high relative humidity in order to mimic cloud formation conditions. Particles which nucleated ice were separated using a counterflow virtual impactor. The size and chemical composition of the ice nuclei was then characterized in situ using a single particle mass spectrometer . Samples were also collected for off line electron microscopic analysis. A particular emphasis was placed on determination of fractions associated with anthropogenic activity and biogenic components.

  20. Foucault on targets.

    PubMed

    Lynch, John

    2004-01-01

    This paper seeks to gain an insight into the behavior of a large NHS trust, in its attempt to meet a 90 percent patient access target, in a week long national audit in March 2003. Why did individuals act in dramatically different ways to their norm over this period. The work of Michel Foucault is used to explore these issues. The discourses of power, knowledge, discipline and governmentality are identified as key foucaudian themes that offer an alternative interpretation of how individuals behave in their place of work. The importance of the historical context of discourse within the NHS cannot be underestimated in shaping the behavior of individuals and groups today. Power and knowledge permeate NHS organizations through disciplinary practices and dressage. Governmentality seeks to maintain the status quo through disciplinary processes such as national healthcare targets. The natural response of NHS organizations is therefore, to seek order and conformity rather than disorder and conflict.

  1. 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.

  2. Controlling High-Frequency Collective Electron Dynamics via Single-Particle Complexity

    NASA Astrophysics Data System (ADS)

    Alexeeva, N.; Greenaway, M. T.; Balanov, A. G.; Makarovsky, O.; Patanè, A.; Gaifullin, M. B.; Kusmartsev, F.; Fromhold, T. M.

    2012-07-01

    We demonstrate, through experiment and theory, enhanced high-frequency current oscillations due to magnetically-induced conduction resonances in superlattices. Strong increase in the ac power originates from complex single-electron dynamics, characterized by abrupt resonant transitions between unbound and localized trajectories, which trigger and shape propagating charge domains. Our data demonstrate that external fields can tune the collective behavior of quantum particles by imprinting configurable patterns in the single-particle classical phase space.

  3. Controlling high-frequency collective electron dynamics via single-particle complexity.

    PubMed

    Alexeeva, N; Greenaway, M T; Balanov, A G; Makarovsky, O; Patanè, A; Gaifullin, M B; Kusmartsev, F; Fromhold, T M

    2012-07-13

    We demonstrate, through experiment and theory, enhanced high-frequency current oscillations due to magnetically-induced conduction resonances in superlattices. Strong increase in the ac power originates from complex single-electron dynamics, characterized by abrupt resonant transitions between unbound and localized trajectories, which trigger and shape propagating charge domains. Our data demonstrate that external fields can tune the collective behavior of quantum particles by imprinting configurable patterns in the single-particle classical phase space.

  4. Single-particle stochastic heat engine

    NASA Astrophysics Data System (ADS)

    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.

  5. 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.

  6. Single-particle machine for quantum thermalization

    SciTech Connect

    Liao Jieqiao; Dong, H.; Sun, C. P.

    2010-05-15

    The long time accumulation of the random actions of a single particle 'reservoir' on its coupled system can transfer some temperature information of its initial state to the coupled system. This dynamic process can be referred to as a quantum thermalization in the sense that the coupled system can reach a stable thermal equilibrium with a temperature equal to that of the reservoir. We illustrate this idea based on the usual micromaser model, in which a series of initially prepared two-level atoms randomly pass through an electromagnetic cavity. It is found that, when the randomly injected atoms are initially prepared in a thermal equilibrium state with a given temperature, the cavity field will reach a thermal equilibrium state with the same temperature as that of the injected atoms. As in two limit cases, the cavity field can be cooled and 'coherently heated' as a maser process, respectively, when the injected atoms are initially prepared in ground and excited states. Especially, when the atoms in equilibrium are driven to possess some coherence, the cavity field may reach a higher temperature in comparison with the injected atoms. We also point out a possible experimental test for our theoretical prediction based on a superconducting circuit QED system.

  7. 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

  8. 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.

  9. Automated data collection in single particle electron microscopy

    PubMed Central

    Tan, Yong Zi; Cheng, Anchi; Potter, Clinton S.; Carragher, Bridget

    2016-01-01

    Automated data collection is an integral part of modern workflows in single particle electron microscopy (EM) research. This review surveys the software packages available for automated single particle EM data collection. The degree of automation at each stage of data collection is evaluated, and the capabilities of the software packages are described. Finally, future trends in automation are discussed. PMID:26671944

  10. Automated data collection in single particle electron microscopy.

    PubMed

    Tan, Yong Zi; Cheng, Anchi; Potter, Clinton S; Carragher, Bridget

    2016-02-01

    Automated data collection is an integral part of modern workflows in single particle electron microscopy (EM) research. This review surveys the software packages available for automated single particle EM data collection. The degree of automation at each stage of data collection is evaluated, and the capabilities of the software packages are described. Finally, future trends in automation are discussed.

  11. 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.

  12. Michel Foucault's Theory of Rhetoric as Epistemic.

    ERIC Educational Resources Information Center

    Foss, Sandra K.; Gill, Ann

    1987-01-01

    Formulates a middle-level theory that explains the process by which rhetroic is epistemic, using Foucault's notion of the discursive formation as a starting point. Discusses five theoretical units derived from Foucault--discursive practices, rules, roles, power, and knowledge--and relationships among them. Analyzes Disneyland, using Foucault's…

  13. The Statement: Foundation of Foucault's Historical Criticism.

    ERIC Educational Resources Information Center

    Blair, Carole

    1987-01-01

    Presents an overview of Michel Foucault's approach to the study of historical systems of thought, arguing that Foucault's view of historical criticism and language-in-use have much to offer rhetorical theory and criticism. Discusses the nature of discourse for Foucault and examines the characteristics of the fundamental discursive datum, the…

  14. Michel Foucault's Theory of Rhetoric as Epistemic.

    ERIC Educational Resources Information Center

    Foss, Sandra K.; Gill, Ann

    1987-01-01

    Formulates a middle-level theory that explains the process by which rhetroic is epistemic, using Foucault's notion of the discursive formation as a starting point. Discusses five theoretical units derived from Foucault--discursive practices, rules, roles, power, and knowledge--and relationships among them. Analyzes Disneyland, using Foucault's…

  15. Single particle dynamics and nonlinear resonances in circular accelerators

    SciTech Connect

    Ruth, R.D.

    1985-11-01

    The purpose of this paper is to introduce the reader to single particle dynamics in circular accelerators with an emphasis on nonlinear resonances. We begin with the Hamiltonian and the equations of motion in the neighborhood of the design orbit. In the linear theory this yields linear betatron oscillations about a closed orbit. It is useful then to introduce the action-angle variables of the linear problem. Next we discuss the nonlinear terms which are present in an actual accelerator, and in particular, we motivate the inclusion of sextupoles to cure chromatic effects. To study the effects of the nonlinear terms, we next discuss canonical perturbation theory which leads us to nonlinear resonances. After showing a few examples of perturbation theory, we abandon it when very close to a resonance. This leads to the study of an isolated resonance in one degree of freedom with a 'time'-dependent Hamiltonian. We see the familiar resonance structure in phase space which is simply closed islands when the nonlinear amplitude dependence of the frequency or 'tune' is included. To show the limits of the validity of the isolated resonance approximation, we discuss two criteria for the onset of chaotic motion. Finally, we study an isolated coupling resonance in two degrees of freedom with a 'time'-dependent Hamiltonian and calculate the two invariants in this case. This leads to a surface of section which is a 2-torus in 4-dimensional phase space. However, we show that it remains a 2-torus when projected into particular 3-dimensional subspaces, and thus can be viewed in perspective.

  16. 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.

  17. 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.

  18. Principles of cryo-EM single-particle image processing

    PubMed Central

    Sigworth, Fred J.

    2016-01-01

    Single-particle reconstruction is the process by which 3D density maps are obtained from a set of low-dose cryo-EM images of individual macromolecules. This review considers the fundamental principles of this process and the steps in the overall workflow for single-particle image processing. Also considered are the limits that image signal-to-noise ratio places on resolution and the distinguishing of heterogeneous particle populations. PMID:26705325

  19. Medical education... meet Michel Foucault.

    PubMed

    Hodges, Brian D; Martimianakis, Maria A; McNaughton, Nancy; Whitehead, Cynthia

    2014-06-01

    There have been repeated calls for the greater use of conceptual frameworks and of theory in medical education. Although it is familiar to few medical educators, Michel Foucault's work is a helpful theoretical and methodological source. This article explores what it means to use a 'Foucauldian approach', presents a sample of Foucault's historical-genealogical studies that are relevant to medical education, and introduces the work of four researchers currently undertaking Foucauldian-inspired medical education research. Although they are not without controversy, Foucauldian approaches are employed by an increasing number of scholars and are helpful in shedding light on what it is possible to think, say and be in medical education. Our hope in sharing this Foucauldian work and perspective is that we might stimulate a dialogue that is forward-looking and optimistic about the possibilities for change in medical education. © 2014 John Wiley & Sons Ltd.

  20. Single particle structure and shapes of exotic Sr isotopes

    NASA Astrophysics Data System (ADS)

    Cruz, Steffen; S1389 Team

    2016-09-01

    States within a nucleus that have different shapes that are close in energy are referred to as shape coexisting. A dramatic occurrence of shape coexisting states is observed in nuclei in the vicinity of Z=40, N=60, which is the subject of substantial current experimental and theoretical effort. An important aspect in this context is the evolution of single particle structure for N < 60 leading up to the shape transition region, which can be calculated with modern large scale shell model calculations using a 78Ni core or Beyond Mean Field Models. One-neutron transfer reactions are a proven tool to study single-particle energies as well as occupation numbers. Here we report on the study of the single-particle structure in 96Sr via (d,p) one-neutron transfer reaction in inverse kinematics. The experiment presented was performed in the ISAC facility using the TIGRESS gamma-ray spectrometer in conjunction with the SHARC charged-particle detector. A thorough analysis of single particle states will improve our understanding of the onset of these unique structures, encouraging the ongoing theoretical discussions. Results discussed in the context of the evolution of single-particle structure will be presented. Work supported by the National Research Council of Canada, the Science and Technology Facilities Council of the United Kingdom, the Natural Sciences and the Engineering Research Council of Canada and the National Science Foundation, USA.

  1. Recent translations of Foucault on mental health.

    PubMed

    Bracken, Pat; Khalfa, Jean; Thomas, Philip

    2007-11-01

    The work of the French philosopher and historian, Michel Foucault, often dealt with subjects either directly or indirectly related to psychiatry. In the past, his work has been largely ignored or rejected by mainstream psychiatry. In the period under review, two important English translations of Foucault's work on psychiatry have been published. Our review focuses on these books, and also looks at some of the recent secondary literature relating to Foucault and mental health. We argue that psychiatry has a lot to gain from a positive engagement with Foucault's ideas.

  2. 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.

  3. 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…

  4. The Pedagogical Effect: On Foucault and Sloterdijk

    ERIC Educational Resources Information Center

    Noguera-Ramírez, Carlos Ernesto

    2017-01-01

    Although Foucault did not produce any particular work devoted to teaching or education, following authors like Hoskin this text aims to show the importance that teaching practices and discourses have in Foucault's analysis, particularly in the analysis of what he called governmentality. If we associate these analyses with the concept of…

  5. 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…

  6. 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…

  7. 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…

  8. 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.

  9. 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.

  10. 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.

  11. Feasible ``Kochen-Specker'' Experiment with Single Particles

    NASA Astrophysics Data System (ADS)

    Simon, Christoph; Żukowski, Marek; Weinfurter, Harald; Zeilinger, Anton

    2000-08-01

    We present a simple experimental scheme which can be used to demonstrate an all-or-nothing-type contradiction between noncontextual hidden variables and quantum mechanics. The scheme, which is inspired by recent ideas by Cabello and García-Alcaine, shows that even for a single particle, path and spin information cannot be predetermined in a noncontextual way.

  12. 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.

  13. 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.

  14. Generalized seniority on a deformed single-particle basis

    NASA Astrophysics Data System (ADS)

    Jia, L. Y.

    2017-09-01

    Recently, I proposed a fast computing scheme for generalized seniority on a spherical single-particle basis [J. Phys. G: Nucl. Part. Phys. 42, 115105 (2015), 10.1088/0954-3899/42/11/115105]. This work redesigns the scheme to make it applicable to deformed single-particle basis. The algorithm is applied to the rare-earth-metal nucleus 94 64 158Gd for intrinsic (body-fixed frame) neutron excitations under the low-momentum NN interaction Vlow -k. By allowing as many as four broken pairs, I compute the lowest 300 intrinsic states of several multipolarities. These states converge well to the exact ones, showing generalized seniority is very effective in truncating the deformed shell model. Under realistic interactions, the picture remains approximately valid: The ground state is a coherent pair condensate and the pairs gradually break up as excitation energy increases.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  16. Single-particle mechanism of magnetostriction in magnetoactive elastomers.

    PubMed

    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.

  17. 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

  18. 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.

  19. 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.

  20. Single particle detection in CMOS compatible photonic crystal nanobeam cavities.

    PubMed

    Quan, Qimin; Floyd, Daniel L; Burgess, Ian B; Deotare, Parag B; Frank, Ian W; Tang, Sindy K Y; Ilic, Rob; Loncar, Marko

    2013-12-30

    We report the label-free detection of single particles using photonic crystal nanobeam cavities fabricated in silicon-on-insulator platform, and embedded inside microfluidic channels fabricated in poly-dimethylsiloxane (PDMS). Our system operates in the telecommunication wavelength band, thus leveraging the widely available, robust and tunable telecom laser sources. Using this approach, we demonstrated the detection of polystyrene nanoparticles with dimensions down to 12.5nm in radius. Furthermore, binding events of a single streptavidin molecule have been observed.

  1. Foucault and the politics of our selves.

    PubMed

    Allen, Amy

    2011-01-01

    Exploring the apparent tension between Foucault's analyses of technologies of domination -- the ways in which the subject is constituted by power-knowledge relations -- and of technologies of the self -- the ways in which individuals constitute themselves through practices of freedom -- this article endeavors to make two points: first, the interpretive claim that Foucault's own attempts to analyse both aspects of the politics of our selves are neither contradictory nor incoherent; and second, the constructive claim that Foucault's analysis of the politics of our selves, though not entirely satisfactory as it stands, provides important resources for the project of critical social theory.

  2. Single Particle Nanoplasmonic Sensing in Individual Nanofluidic Channels

    PubMed Central

    2016-01-01

    Nanoplasmonics allows label-free optical sensing and spectroscopy at the single nanoparticle level by exploiting plasmonic excitations in metal nanoparticles. Nanofluidics offers exclusive possibilities for applying and controlling fluid flow and mass transport at the nanoscale and toward nanosized objects. Here, we combine these two concepts in a single device, by integrating single particle nanoplasmonic sensing with nanofluidics using advanced nanofabrication. The developed devices enable on-chip referenced parallel single particle nanoplasmonic sensing inside multiple individual nanofluidic channels with dimensions down to the 100 nm range. Beyond detailed discussion of the nanofabrication, general device characterization, and parallelized single particle plasmonic readout concepts, we demonstrate device function on two examples: (i) in situ measurements of local buffer concentrations inside a nanofluidic channel; (ii) real time binding kinetics of alkanethiol molecules to a single plasmonic nanonatenna sensor in a single nanochannel. Our concept thus provides a powerful solution for controlling mass transport to and from individual (plasmonic) nanoparticles, which in a long-term perspective offers unique opportunities for label-free detection of analyte molecules at low concentrations and for fundamental studies of fluids in extreme confinement. PMID:27960495

  3. 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.

  4. 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.

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

    DOE PAGES

    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

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. Microswimmers - From Single Particle Motion to Collective Behavior

    NASA Astrophysics Data System (ADS)

    Gompper, Gerhard; Bechinger, Clemens; Herminghaus, Stephan; Isele-Holder, Rolf; Kaupp, U. Benjamin; Löwen, Hartmut; Stark, Holger; Winkler, Roland G.

    2016-11-01

    Locomotion of autonomous microswimmers is a fascinating field at the cutting edge of science. It combines the biophysics of self-propulsion via motor proteins, artificial propulsion mechanisms, swimming strategies at low Reynolds numbers, the hydrodynamic interaction of swimmers, and the collective motion and synchronisation of large numbers of agents. The articles of this Special Issue are based on the lecture notes of an international summer school, which was organized by the DFG Priority Programme 1726 "Microswimmers - From Single Particle Motion to Collective Behaviour" in the fall of 2015. The minireviews provide a broad overview of the field, covering both elementary and advanced material, as well as selected areas from current research.

  13. Single-particle hydrodynamics in DPD: A new formulation

    NASA Astrophysics Data System (ADS)

    Pan, W.; Pivkin, I. V.; Karniadakis, G. E.

    2008-10-01

    We present a new formulation of dissipative particle dynamics (DPD) that leads to correct hydrodynamics in flows around bluff bodies represented by a single particle. In particular, we introduce a shear drag coefficient and a corresponding term in the dissipative force, which along with the angular momentum incorporate non-central shear forces between particles and preserve angular momentum. We consider several prototype flows to verify the performance of the proposed formulation with comparisons against theoretical and continuum-based simulation results. Our method is similar to the Fluid Particle Method (FPM) of Espanol (Phys. Rev. E, 57 (1998) 2930) and it has the computational and implementation simplicity of the standard DPD approach.

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

    SciTech Connect

    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.

  15. Effect of ICRF Heating on Single Particle Confinement in Tokamaks,

    DTIC Science & Technology

    1980-03-01

    80 K W WHANG. 6 .J MORALES N0001IG75C4476 W4CLASSIFlED PP"-73 ML IND 4, LAa4 5 057 Effect of ICRP Heating on Single Particle Confinement in Tokamaks ...bas =akapmwd a b 11 1Af b tmhmdin4 -2- ABSTRACT The simultaneous effect of ion heating and spatial diffusion due to ICRF heating in tokamak geometry... Tokamak confinement devices. Previous theoretical studies I1 2 of this topic have dealt with important questions related to the efficiency of the heating

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

    DOE PAGES

    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.

  17. Single-particle and single-hole spectra in UCa

    SciTech Connect

    Jing Xiao-gong; Li Cheng-zu; Yang Shan-de; Wu Shi-shu

    1987-07-01

    The single-particle (sp) and single-hole spectra in UCa are calculated with the Paris potential by two methods: (1) the eigenvalue equation derived from the sp Green function and (2) the sp potential u/sub //sub US / = M/sub //sub US /(epsilon/sub US /) defined in terms of the mass operator M/sub //sub US /( ). The energy dependence of G matrix is taken into account rigorously. Our results agree with the experimental values fairly well. It is found that the Paris potential yields a somewhat better result than the RSC potential.

  18. Stability and single-particle properties of bosonized Fermi liquids

    NASA Astrophysics Data System (ADS)

    Houghton, A.; Kwon, H.-J.; Marston, J. B.

    1994-07-01

    We study the stability and single-particle properties of Fermi liquids in spatial dimensions greater than one via bosonization. For smooth nonsingular Fermi-liquid interactions we obtain Shankar's renormalization-group flows to second order in the BCS coupling and reproduce well-known results for quasiparticle lifetimes. We demonstrate by explicit calculation that spin-charge separation does not occur when the Fermi-liquid interactions are regular. We also explore the relationship between quantized bosonic excitations and zero-sound modes and present a concise derivation of both the spin and the charge collective-mode equations. Finally we discuss some aspects of singular Fermi-liquid interactions.

  19. 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

  20. Quantum heat fluctuations of single-particle sources.

    PubMed

    Battista, F; Moskalets, M; Albert, M; Samuelsson, P

    2013-03-22

    Optimal single electron sources emit regular streams of particles, displaying no low-frequency charge current noise. Because of the wave packet nature of the emitted particles, the energy is, however, fluctuating, giving rise to heat current noise. We investigate theoretically this quantum source of heat noise for an emitter coupled to an electronic probe in the hot-electron regime. The distribution of temperature and potential fluctuations induced in the probe is shown to provide direct information on the single-particle wave function properties and display strong nonclassical features.

  1. Single-particle excitations in disordered Weyl fluids

    NASA Astrophysics Data System (ADS)

    Pixley, J. H.; Chou, Yang-Zhi; Goswami, Pallab; Huse, David A.; Nandkishore, Rahul; Radzihovsky, Leo; Das Sarma, S.

    2017-06-01

    We theoretically study the single-particle Green function of a three-dimensional disordered Weyl semimetal using a combination of techniques. These include analytic T -matrix and renormalization group methods with complementary regimes of validity and an exact numerical approach based on the kernel polynomial technique. We show that at any nonzero disorder, Weyl excitations are not ballistic: They instead have a nonzero linewidth that for weak short-range disorder arises from nonperturbative resonant impurity scattering. Perturbative approaches find a quantum critical point between a semimetal and a metal at a finite disorder strength, but this transition is avoided due to nonperturbative effects. At moderate disorder strength and intermediate energies the avoided quantum critical point renormalizes the scaling of single-particle properties. In this regime we compute numerically the anomalous dimension of the fermion field and find η =0.13 ±0.04 , which agrees well with a renormalization group analysis (η =0.125 ). Our predictions can be directly tested by ARPES and STM measurements in samples dominated by neutral impurities.

  2. New instrument for tribocharge measurement due to single particle impacts.

    PubMed

    Watanabe, Hideo; Ghadiri, Mojtaba; Matsuyama, Tatsushi; Ding, Yu Long; Pitt, Kendal G

    2007-02-01

    During particulate solid processing, particle-particle and particle-wall collisions can generate electrostatic charges. This may lead to a variety of problems ranging from fire and explosion hazards to segregation, caking, and blocking. A fundamental understanding of the particle charging in such situations is therefore essential. For this purpose we have developed a new device that can measure charge transfer due to impact between a single particle and a metal plate. The device consists of an impact test system and two sets of Faraday cage and preamplifier for charge measurement. With current amplifiers, high-resolution measurements of particle charges of approximately 1 and 10 fC have been achieved before and after the impact, respectively. The device allows charge measurements of single particles with a size as small as approximately 100 microm impacting on the target at different incident angles with a velocity up to about 80 m/s. Further analyses of the charge transfer as a function of particle initial charge define an equilibrium charge, i.e., an initial charge level prior to impact for which no net charge transfer would occur as a result of impact.

  3. New instrument for tribocharge measurement due to single particle impacts

    NASA Astrophysics Data System (ADS)

    Watanabe, Hideo; Ghadiri, Mojtaba; Matsuyama, Tatsushi; Long Ding, Yu; Pitt, Kendal G.

    2007-02-01

    During particulate solid processing, particle-particle and particle-wall collisions can generate electrostatic charges. This may lead to a variety of problems ranging from fire and explosion hazards to segregation, caking, and blocking. A fundamental understanding of the particle charging in such situations is therefore essential. For this purpose we have developed a new device that can measure charge transfer due to impact between a single particle and a metal plate. The device consists of an impact test system and two sets of Faraday cage and preamplifier for charge measurement. With current amplifiers, high-resolution measurements of particle charges of approximately 1 and 10fC have been achieved before and after the impact, respectively. The device allows charge measurements of single particles with a size as small as ˜100μm impacting on the target at different incident angles with a velocity up to about 80m/s. Further analyses of the charge transfer as a function of particle initial charge define an equilibrium charge, i.e., an initial charge level prior to impact for which no net charge transfer would occur as a result of impact.

  4. New instrument for tribocharge measurement due to single particle impacts

    SciTech Connect

    Watanabe, Hideo; Ghadiri, Mojtaba; Matsuyama, Tatsushi; Ding Yulong; Pitt, Kendal G.

    2007-02-15

    During particulate solid processing, particle-particle and particle-wall collisions can generate electrostatic charges. This may lead to a variety of problems ranging from fire and explosion hazards to segregation, caking, and blocking. A fundamental understanding of the particle charging in such situations is therefore essential. For this purpose we have developed a new device that can measure charge transfer due to impact between a single particle and a metal plate. The device consists of an impact test system and two sets of Faraday cage and preamplifier for charge measurement. With current amplifiers, high-resolution measurements of particle charges of approximately 1 and 10 fC have been achieved before and after the impact, respectively. The device allows charge measurements of single particles with a size as small as {approx}100 {mu}m impacting on the target at different incident angles with a velocity up to about 80 m/s. Further analyses of the charge transfer as a function of particle initial charge define an equilibrium charge, i.e., an initial charge level prior to impact for which no net charge transfer would occur as a result of impact.

  5. Single particle maximum likelihood reconstruction from superresolution microscopy images

    PubMed Central

    Verdier, Timothée; Gunzenhauser, Julia; Manley, Suliana; Castelnovo, Martin

    2017-01-01

    Point localization superresolution microscopy enables fluorescently tagged molecules to be imaged beyond the optical diffraction limit, reaching single molecule localization precisions down to a few nanometers. For small objects whose sizes are few times this precision, localization uncertainty prevents the straightforward extraction of a structural model from the reconstructed images. We demonstrate in the present work that this limitation can be overcome at the single particle level, requiring no particle averaging, by using a maximum likelihood reconstruction (MLR) method perfectly suited to the stochastic nature of such superresolution imaging. We validate this method by extracting structural information from both simulated and experimental PALM data of immature virus-like particles of the Human Immunodeficiency Virus (HIV-1). MLR allows us to measure the radii of individual viruses with precision of a few nanometers and confirms the incomplete closure of the viral protein lattice. The quantitative results of our analysis are consistent with previous cryoelectron microscopy characterizations. Our study establishes the framework for a method that can be broadly applied to PALM data to determine the structural parameters for an existing structural model, and is particularly well suited to heterogeneous features due to its single particle implementation. PMID:28253349

  6. Tensor interaction contributions to single-particle energies

    SciTech Connect

    Brown, B. A.; Duguet, T.; Otsuka, T.; Abe, D.; Suzuki, T.

    2006-12-15

    We calculate the contribution of the nucleon-nucleon tensor interaction to single-particle energies with finite-range G-matrix potentials and with zero-range Skyrme potentials. The Skx Skyrme parameters including the zero-range tensor terms with strengths calibrated to the finite-range results are refitted to nuclear properties. The fit allows the zero-range proton-neutron tensor interaction as calibrated to the finite-range potential results which gives the observed change in the single-particle gap {epsilon}(h{sub 11/2})-{epsilon}(g{sub 7/2}) going from {sup 114}Sn to {sup 132}Sn. However, the experimental l dependence of the spin-orbit splittings in {sup 132}Sn and {sup 208}Pb is not well described when the tensor is added, owing to a change in the radial dependence of the total spin-orbit potential. The gap shift and a good fit to the l dependence can be recovered when the like-particle tensor interaction is opposite in sign to that required for the G matrix.

  7. Single particle maximum likelihood reconstruction from superresolution microscopy images.

    PubMed

    Verdier, Timothée; Gunzenhauser, Julia; Manley, Suliana; Castelnovo, Martin

    2017-01-01

    Point localization superresolution microscopy enables fluorescently tagged molecules to be imaged beyond the optical diffraction limit, reaching single molecule localization precisions down to a few nanometers. For small objects whose sizes are few times this precision, localization uncertainty prevents the straightforward extraction of a structural model from the reconstructed images. We demonstrate in the present work that this limitation can be overcome at the single particle level, requiring no particle averaging, by using a maximum likelihood reconstruction (MLR) method perfectly suited to the stochastic nature of such superresolution imaging. We validate this method by extracting structural information from both simulated and experimental PALM data of immature virus-like particles of the Human Immunodeficiency Virus (HIV-1). MLR allows us to measure the radii of individual viruses with precision of a few nanometers and confirms the incomplete closure of the viral protein lattice. The quantitative results of our analysis are consistent with previous cryoelectron microscopy characterizations. Our study establishes the framework for a method that can be broadly applied to PALM data to determine the structural parameters for an existing structural model, and is particularly well suited to heterogeneous features due to its single particle implementation.

  8. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Computational modeling of single particle scattering over large distances

    NASA Astrophysics Data System (ADS)

    Rapp, Rebecca; Plumley, Rajan; McCracken, Michael

    2016-09-01

    We present a Monte Carlo simulation of the propagation of a single particle through a large three-dimensional volume under the influence of individual scattering events. In such systems, short paths can be quickly and accurately simulated using random walks defined by individual scattering parameters, but the simulation time greatly increases as the size of the space grows. We present a method for reducing the overall simulation time by restricting the simulation to a cube of unit length; each `cell' is characterized by a set of parameters which dictate the distributions of allowable step lengths and polar scattering angles. We model propagation over large distances by constructing a lattice of cells with physical parameters that depend on position, such that the full set would represent a space within the entire volume available to the particle. With these, we propose the use of Markov chains to determine a probable path for the particle, thereby removing the need to simulate every step in the particle's path. For a single particle with constant velocity, we can use the step statistics to determine the travel time of the particle. We investigate the effect of scattering parameters such as average step distance and possible scattering angles on the probabilities of a cell.

  10. Foucault on methadone: beyond biopower.

    PubMed

    Keane, Helen

    2009-09-01

    This essay reviews four texts which critically analyse methadone maintenance therapy using Foucault as a key theoretical framework: [Friedman, J., & Alicea, M. (2001). Surviving heroin: Interviews with women in methadone clinics. Florida: University Press of Florida], [Bourgois, P. (2000). Disciplining addictions: The bio-politics of methadone and heroin in the United States. Culture Medicine and Psychiatry, 24, 165-195], [Bull, M. (2008). Governing the heroin trade: From treaties to treatment. Ashgate: Aldershot], and [Fraser, S., & valentine, k. (2008). Substance & substitution: Methadone subjects in liberal societies. New York: Palgrave Macmillan]. Taken together these works demonstrate one trajectory in the development of critical drug studies over the past decade. While all four view MMT as a regulatory technology which aims to create productive and obedient subjects, their understandings of the power relations of the clinic are quite distinct. The first two texts emphasise the social control of drug users, the third, issues of governmentality and liberal political practice, while the fourth engages with ontological questions about substances themselves. Thus while Foucauldian analysis has become familiar in social studies of drugs and alcohol, new uses for its conceptual tools continue to emerge.

  11. The domestication of Foucault: Government, critique, war.

    PubMed

    Allen, Ansgar; Goddard, Roy

    2014-12-01

    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.

  12. A clock referenced to the rest mass of a single particle

    NASA Astrophysics Data System (ADS)

    Yu, Chenghui; Lan, Shau-Yu; Kuan, Pei-Chen; Estey, Brian; English, Damon; Brown, Justin; Hohensee, Michael; Müller, Holger

    2013-05-01

    We demonstrate the operation of a Compton clock, one whose frequency is referenced to the mass of a single particle. Though it is well known that the wave function of a massive particle accumulates phase at the Compton frequency ω0 = mc2 / ℏ in its rest frame, such oscillations are too fast to directly detect (3 ×1025 Hz for 133Cs). We use an optical frequency comb and a Ramsey-Bordé matter-wave interferometer to stabilize an oscillator to a chosen subharmonic of ω0 with a precision of 4 parts per billion (at 6 hours timescale). Although this is far below the precision of modern frequency standards, its precision is sufficient, in combination with the spheres constructed by the Avogadro Project, to calibrate macroscopic masses with an accuracy of 30 ppb, in terms of the second. This clock may be useful for testing fundamental physics by demonstrating that its frequency redshifts in a gravitational potential in the same way that conventional frequency standards do. Implementation of a clock referenced to the mass of an elementary particle, such as an electron or positron, could also enable new experimental tests of Lorentz and CPT symmetry.

  13. 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.

  14. Quantitative Analysis of Single Particle Trajectories: Mean Maximal Excursion Method

    PubMed Central

    Tejedor, Vincent; Bénichou, Olivier; Voituriez, Raphael; Jungmann, Ralf; Simmel, Friedrich; Selhuber-Unkel, Christine; Oddershede, Lene B.; Metzler, Ralf

    2010-01-01

    An increasing number of experimental studies employ single particle tracking to probe the physical environment in complex systems. We here propose and discuss what we believe are new methods to analyze the time series of the particle traces, in particular, for subdiffusion phenomena. We discuss the statistical properties of mean maximal excursions (MMEs), i.e., the maximal distance covered by a test particle up to time t. Compared to traditional methods focusing on the mean-squared displacement we show that the MME analysis performs better in the determination of the anomalous diffusion exponent. We also demonstrate that combination of regular moments with moments of the MME method provides additional criteria to determine the exact physical nature of the underlying stochastic subdiffusion processes. We put the methods to test using experimental data as well as simulated time series from different models for normal and anomalous dynamics such as diffusion on fractals, continuous time random walks, and fractional Brownian motion. PMID:20371337

  15. Holding forces of single-particle dielectrophoretic traps.

    PubMed Central

    Voldman, J; Braff, R A; Toner, M; Gray, M L; Schmidt, M A

    2001-01-01

    We present experimental results and modeling on the efficacy of dielectrophoresis-based single-particle traps. Dielectrophoretic forces, caused by the interaction of nonuniform electric fields with objects, have been used to make planar quadrupole traps that can trap single beads. A simple experimental protocol was then used to measure how well the traps could hold beads against destabilizing fluid flows. These were compared with predictions from modeling and found to be in close agreement, allowing the determination of sub-piconewton forces. This not only validates our ability to model dielectrophoretic forces in these traps but also gives insight into the physical behavior of particles in dielectrophoresis-based traps. Anomalous frequency effects, not explainable by dielectrophoretic forces alone, were also encountered and attributed to electrohydrodynamic flows. Such knowledge can now be used to design traps for cell-based applications. PMID:11159423

  16. Reconstructing an icosahedral virus from single-particle diffraction experiments.

    PubMed

    Saldin, D K; Poon, H-C; Schwander, P; Uddin, M; Schmidt, M

    2011-08-29

    The first experimental data from single-particle scattering experiments from free electron lasers (FELs) are now becoming available. The first such experiments are being performed on relatively large objects such as viruses, which produce relatively low-resolution, low-noise diffraction patterns in so-called "diffract-and-destroy" experiments. We describe a very simple test on the angular correlations of measured diffraction data to determine if the scattering is from an icosahedral particle. If this is confirmed, the efficient algorithm proposed can then combine diffraction data from multiple shots of particles in random unknown orientations to generate a full 3D image of the icosahedral particle. We demonstrate this with a simulation for the satellite tobacco necrosis virus (STNV), the atomic coordinates of whose asymmetric unit is given in Protein Data Bank entry 2BUK.

  17. Magnetophoretic circuits for digital control of single particles and cells

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  18. Analysis of Single Particle Trajectories: From Normal to Anomalous Diffusion

    NASA Astrophysics Data System (ADS)

    Metzler, R.; Tejedor, V.; Jeon, J.-H.; He, Y.; Deng, W. H.; Burov, S.; Barkai, E.

    2009-05-01

    With modern experimental tools it is possible to track the motion of single nanoparticles in real time, even in complex environments such as biological cells. The quest is then to reliably evaluate the time series of individual trajectories. While this is straightforward for particles performing normal Brownian motion, interesting subtleties occur in the case of anomalously diffusing particles: it is no longer granted that the long time average equals the ensemble average. We here discuss for two different models of anomalous diffusion the detailed behaviour of time averaged mean squared displacement and related quantities, and present possible criteria to analyse single particle trajectories. An important finding is that although the time average may suggest normal diffusion the actual process may in fact be subdiffusive.

  19. Modeling Single Particle Transport in Stochastic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Hudson, Ben; Fiksel, Gennady; Prager, Stewart

    2001-10-01

    Single particle transport in a stochastic magnetic field is simulated via code ION and RIO. Developed in collaboration with a group in Novosibirsk, Russia, they simulate both single ion and multiple ion trajectories in a stochastic magnetic field. A sharp decrease in the relative diffusion of ions to magnetic field lines is seen in two gyro-radii regimes. One is explainable from the unbroken flux surfaces near the edge of the plasma. The other is thought to be due to a "gyro-averaging" effect that occurs when the gyro-radius exceeds the radial correlation length of the field lines. The simulations indicate a decrease in expected transport, most strongly as a function of gyro-radius, which will be tested experimentally with the MST neutral beam injector.

  20. Hierarchical Ag mesostructures for single particle SERS substrate

    NASA Astrophysics Data System (ADS)

    Xu, Minwei; Zhang, Yin

    2017-01-01

    Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250-500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 106.

  1. 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

  2. Sample Targeting During Single-Particle Single-Cell Irradiation

    NASA Astrophysics Data System (ADS)

    Bigelow, A. W.; Randers-Pehrson, G.; Michel, K. A.; Brenner, D. J.; Dymnikov, A. D.

    2003-08-01

    An apertured microbeam is used for single-particle single-cell irradiation to study radiobiological effects at the Radiological Research Accelerator Facility (RARAF), Center for Radiological Research, Columbia University. The present sample targeting system involves imaging techniques and a stepping motor stage to sequentially position a cell nucleus above a vertical ion beam. An interest expressed by the biology research community in targeting subnuclear components has spurred the development of microbeam II, a next-generation facility to include a focused ion beam and a more precise sample manipulator, a voice coil stage. Sample positioning precision will rely on a feedback circuit incorporating linear variable differential transformer (LVDT) position measurements. In addition, post-lens electrostatic deflection is a contender for a point-and-shoot system that could speed up the cell irradiation process for cells within an image frame. Crucial to this development is that ion beam blow up must be minimal during deflection.

  3. Single particle behaviour at (and away from) stability

    NASA Astrophysics Data System (ADS)

    Duflo, J.; Zuker, A. P.

    1998-12-01

    Short of proposing a full microscopic mass formula, we outline the steps that should make it possible. The construction rests on defining the nuclear monopole Hamiltonian, Hm that has to be extracted phenomenologically because of the bad saturation properties of the realistic forces. We propose a preliminary form of Hm that makes clear the origin of shell effects, and with only three paraters, reproduces the known spectra of particle and hole states on doubly magic cores to within 300 keV. Predictions are made for the yet unobserved levels around 132Sn, and those associated to 22O, 34,42Si, 68,78Ni, 100Sn and for the particle-hole gaps in these nuclei. Finally we analyze the single particle gaps for the N=50 and 82 isotones, to conclude that the major closures are likely to persist away from stability.

  4. 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.

  5. Single-particle mapping of nonequilibrium nanocrystal transformations

    NASA Astrophysics Data System (ADS)

    Ye, Xingchen; Jones, Matthew R.; Frechette, Layne B.; Chen, Qian; Powers, Alexander S.; Ercius, Peter; Dunn, Gabriel; Rotskoff, Grant M.; Nguyen, Son C.; Adiga, Vivekananda P.; Zettl, Alex; Rabani, Eran; Geissler, Phillip L.; Alivisatos, A. Paul

    2016-11-01

    Chemists have developed mechanistic insight into numerous chemical reactions by thoroughly characterizing nonequilibrium species. Although methods to probe these processes are well established for molecules, analogous techniques for understanding intermediate structures in nanomaterials have been lacking. We monitor the shape evolution of individual anisotropic gold nanostructures as they are oxidatively etched in a graphene liquid cell with a controlled redox environment. Short-lived, nonequilibrium nanocrystals are observed, structurally analyzed, and rationalized through Monte Carlo simulations. Understanding these reaction trajectories provides important fundamental insight connecting high-energy nanocrystal morphologies to the development of kinetically stabilized surface features and demonstrates the importance of developing tools capable of probing short-lived nanoscale species at the single-particle level.

  6. 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.

  7. Single-particle mapping of nonequilibrium nanocrystal transformations.

    PubMed

    Ye, Xingchen; Jones, Matthew R; Frechette, Layne B; Chen, Qian; Powers, Alexander S; Ercius, Peter; Dunn, Gabriel; Rotskoff, Grant M; Nguyen, Son C; Adiga, Vivekananda P; Zettl, Alex; Rabani, Eran; Geissler, Phillip L; Alivisatos, A Paul

    2016-11-18

    Chemists have developed mechanistic insight into numerous chemical reactions by thoroughly characterizing nonequilibrium species. Although methods to probe these processes are well established for molecules, analogous techniques for understanding intermediate structures in nanomaterials have been lacking. We monitor the shape evolution of individual anisotropic gold nanostructures as they are oxidatively etched in a graphene liquid cell with a controlled redox environment. Short-lived, nonequilibrium nanocrystals are observed, structurally analyzed, and rationalized through Monte Carlo simulations. Understanding these reaction trajectories provides important fundamental insight connecting high-energy nanocrystal morphologies to the development of kinetically stabilized surface features and demonstrates the importance of developing tools capable of probing short-lived nanoscale species at the single-particle level.

  8. Single particle friction tests with cellulose acetate sphere samples

    SciTech Connect

    Tuezen, U.

    1989-05-31

    This reporter represents a detailed account of all the experimental work carried out for LLNL using the ''single particle shear cell'' in the department of Chemical Process Engineering of Surrey University, Guildford, United Kingdom. Experimental work with two spheres in contact was performed. Particles were positioned into the specially made sample holders by the micro screws. The contact centres were lined up under the magnifying glass. The behavior of the interparticle contact region between the two spheres was examined by performing the following series of tests: (i) normal force versus normal displacement test, (ii) tangential force limit at gross sliding with increased normal load and decreasing normal load, (iii) tangential force versus micro displacement during initial loading to friction limit and during unloading from friction limit. Work was also performed on single sphere against a flat wall surface. Results are discussed. 34 figs.

  9. 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.

  10. 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.

  11. Reconstructing an icosahedral virus from single-particle diffraction experiments

    NASA Astrophysics Data System (ADS)

    Saldin, D. K.; Poon, H.-C.; Schwander, P.; Uddin, M.; Schmidt, M.

    2011-08-01

    The first experimental data from single-particle scattering experiments from free electron lasers (FELs) are now becoming available. The first such experiments are being performed on relatively large objects such as viruses, which produce relatively low-resolution, low-noise diffraction patterns in so-called ``diffract-and-destroy'' experiments. We describe a very simple test on the angular correlations of measured diffraction data to determine if the scattering is from an icosahedral particle. If this is confirmed, the efficient algorithm proposed can then combine diffraction data from multiple shots of particles in random unknown orientations to generate a full 3D image of the icosahedral particle. We demonstrate this with a simulation for the satellite tobacco necrosis virus (STNV), the atomic coordinates of whose asymmetric unit is given in Protein Data Bank entry 2BUK.

  12. Magnetophoretic circuits for digital control of single particles and cells.

    PubMed

    Lim, Byeonghwa; Reddy, Venu; Hu, XingHao; Kim, KunWoo; Jadhav, Mital; Abedini-Nassab, Roozbeh; Noh, Young-Woock; Lim, Yong Taik; Yellen, Benjamin B; Kim, CheolGi

    2014-05-14

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

  13. "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…

  14. 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…

  15. "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…

  16. 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…

  17. 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…

  18. 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…

  19. 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.

  20. 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…

  1. 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…

  2. "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 illustrative…

  3. "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 illustrative…

  4. 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…

  5. 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…

  6. Microscopic calculations of {lambda} single-particle energies.

    SciTech Connect

    Usmani, Q. N.

    1998-02-12

    {Lambda} binding energy data for total baryon number A {le} 208 and for {Lambda} angular momenta {ell}{sub {Lambda}} {le} 3 are analyzed in terms of phenomenological (but generally consistent with meson-exchange) {Lambda}N and {Lambda}NN potentials. The Fermi-Hypernetted-Chain technique is used to calculate the expectation values for the {Lambda} binding to nuclear matter. Accurate effective {Lambda}N and {Lambda}NN potentials are obtained which are folded with the core nucleus nucleon densities to calculate the {Lambda} single particle potential U{sub {Lambda}}(r). We use a dispersive {Lambda}NN potential but also include an explicit {rho} dependence to allow for reduced repulsion in the surface, and the best fits have a large {rho} dependence giving consistency with the variational Monte Carlo calculations for {sub {Lambda}}{sup 5}He. The exchange fraction of the {Lambda}N space-exchange potential is found to be 0.2-0.3 corresponding to m{sub {Lambda}}* {approx_equal} (0.74-0.82)m{sub {Lambda}}. Charge symmetry breaking is found to be significant for heavy hypernuclei with a large neutron excess, with a strength consistent with that obtained from the A = 4 hypernuclei.

  7. Single-particle and collective excitations in Ni62

    DOE PAGES

    Albers, M.; Zhu, S.; Ayangeakaa, A. D.; ...

    2016-09-01

    In this study, level sequences of rotational character have been observed in several nuclei in the A = 60 mass region. The importance of the deformation-driving πf7/2 and νg9/2 orbitals on the onset of nuclear deformation is stressed. A measurement was performed in order to identify collective rotational structures in the relatively neutron-rich 62Ni isotope. Here, the 26Mg(48Ca,2α4nγ)62Ni complex reaction at beam energies between 275 and 320 MeV was utilized. Reaction products were identified in mass (A) and charge (Z) with the fragment mass analyzer (FMA) and γ rays were detected with the Gammasphere array. As a result, two collectivemore » bands, built upon states of single-particle character, were identified and sizable deformation was assigned to both sequences based on the measured transitional quadrupole moments, herewith quantifying the deformation at high spin. In conclusion, based on cranked Nilsson-Strutinsky calculations and comparisons with deformed bands in the A = 60 mass region, the two rotational bands are understood as being associated with configurations involving multiple f7/2 protons and g9/2 neutrons, driving the nucleus to sizable prolate deformation.« less

  8. Single particle conformations of human serum albumin by electron microscopy.

    PubMed

    Ueno, Yutaka; Mio, Muneyo; Sato, Chikara; Mio, Kazuhiro

    2007-06-01

    Using single particle images taken by electron microscopy, pH-dependent conformational changes of human serum albumin were investigated. Despite the noisy particle images of negatively stained serum albumin (67 kDa), our novel algorithm for automated particle picking and reference-free classification resulted in the appropriate grouping of the particle images. Iteratively aligned particle images in the same group provided recognizable image features for individual groups. In a pH 7.0 study, monomer images were consistent with an available crystal structure model; the dimer images were separated into different classes. At pH 3.5, the monomer images were similar to those at pH 7.0; slight differences included a small number of elongated conformations and increased population of larger multimers. Our images were also compared with projection images of an atomic model from crystallography, and demonstrated consistency of the molecular conformation both at pH 7.0 and pH 3.5. Our classification method was effective in discriminating monomers from a mixture of different conformations of the protein, enabling the study of the conformational dynamics of small proteins, using the atomic model as a reference.

  9. Single particle raster image analysis of diffusion for particle mixtures.

    PubMed

    Longfils, M; Röding, M; Altskär, A; Schuster, E; Lorén, N; Särkkä, A; Rudemo, M

    2017-09-01

    Recently we complemented the raster image correlation spectroscopy (RICS) method of analysing raster images via estimation of the image correlation function with the method single particle raster image analysis (SPRIA). In SPRIA, individual particles are identified and the diffusion coefficient of each particle is estimated by a maximum likelihood method. In this paper, we extend the SPRIA method to analyse mixtures of particles with a finite set of diffusion coefficients in a homogeneous medium. In examples with simulated and experimental data with two and three different diffusion coefficients, we show that SPRIA gives accurate estimates of the diffusion coefficients and their proportions. A simple technique for finding the number of different diffusion coefficients is also suggested. Further, we study the use of RICS for mixtures with two different diffusion coefficents and investigate, by plotting level curves of the correlation function, how large the quotient between diffusion coefficients needs to be in order to allow discrimination between models with one and two diffusion coefficients. We also describe a minor correction (compared to published papers) of the RICS autocorrelation function. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  10. Automation in single-particle electron microscopy connecting the pieces.

    PubMed

    Lyumkis, Dmitry; Moeller, Arne; Cheng, Anchi; Herold, Amber; Hou, Eric; Irving, Christopher; Jacovetty, Erica L; Lau, Pick-Wei; Mulder, Anke M; Pulokas, James; Quispe, Joel D; Voss, Neil R; Potter, Clinton S; Carragher, Bridget

    2010-01-01

    Throughout the history of single-particle electron microscopy (EM), automated technologies have seen varying degrees of emphasis and development, usually depending upon the contemporary demands of the field. We are currently faced with increasingly sophisticated devices for specimen preparation, vast increases in the size of collected data sets, comprehensive algorithms for image processing, sophisticated tools for quality assessment, and an influx of interested scientists from outside the field who might lack the skills of experienced microscopists. This situation places automated techniques in high demand. In this chapter, we provide a generic definition of and discuss some of the most important advances in automated approaches to specimen preparation, grid handling, robotic screening, microscope calibrations, data acquisition, image processing, and computational infrastructure. Each section describes the general problem and then provides examples of how that problem has been addressed through automation, highlighting available processing packages, and sometimes describing the particular approach at the National Resource for Automated Molecular Microscopy (NRAMM). We contrast the more familiar manual procedures with automated approaches, emphasizing breakthroughs as well as current limitations. Finally, we speculate on future directions and improvements in automated technologies. Our overall goal is to present automation as more than simply a tool to save time. Rather, we aim to illustrate that automation is a comprehensive and versatile strategy that can deliver biological information on an unprecedented scale beyond the scope available with classical manual approaches. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. Manipulation and confinement of single particles using fluid flow.

    PubMed

    Tanyeri, Melikhan; Schroeder, Charles M

    2013-06-12

    High precision control of micro- and nanoscale objects in aqueous media is an essential technology for nanoscience and engineering. Existing methods for particle trapping primarily depend on optical, magnetic, electrokinetic, and acoustic fields. In this work, we report a new hydrodynamic flow based approach that allows for fine-scale manipulation and positioning of single micro- and nanoscale particles using automated fluid flow. As a proof-of-concept, we demonstrate trapping and two-dimensional (2D) manipulation of 500 nm and 2.2 μm diameter particles with a positioning precision as small as 180 nm during confinement. By adjusting a single flow parameter, we further show that the shape of the effective trap potential can be efficiently controlled. Finally, we demonstrate two distinct features of the flow-based trapping method, including isolation of a single particle from a crowded particle solution and active control over the surrounding medium of a trapped object. The 2D flow-based trapping method described here further expands the micro/nanomanipulation toolbox for small particles and holds strong promise for applications in biology, chemistry, and materials research.

  12. Optical microresonators as single-particle absorption spectrometers

    NASA Astrophysics Data System (ADS)

    Heylman, Kevin D.; Thakkar, Niket; Horak, Erik H.; Quillin, Steven C.; Cherqui, Charles; Knapper, Kassandra A.; Masiello, David J.; Goldsmith, Randall H.

    2016-12-01

    Optical measurements of nanoscale objects offer major insights into fundamental biological, material and photonic properties. In absorption spectroscopy, sensitivity limits applications at the nanoscale. Here, we present a new single-particle double-modulation photothermal absorption spectroscopy method that employs on-chip optical whispering-gallery-mode (WGM) microresonators as ultrasensitive thermometers. Optical excitation of a nanoscale object on the microresonator produces increased local temperatures that are proportional to the absorption cross-section of the object. We resolve photothermal shifts in the resonance frequency of the microresonator that are smaller than 100 Hz, orders of magnitude smaller than previous WGM sensing schemes. The application of our new technique to single gold nanorods reveals a dense array of sharp Fano resonances arising from the coupling between the localized surface plasmon of the gold nanorod and the WGMs of the resonator, allowing for the exploration of plasmonic-photonic hybridization. In terms of the wider applicability, our approach adds label-free spectroscopic identification to microresonator-based detection schemes.

  13. Using Single-Particle Flourescence to Detect Bioaerosols

    NASA Astrophysics Data System (ADS)

    Fernandez, Elena; Huang, Hermes; Pan, Yong-Le; Hill, Steven; Pinnick, Ronald; Chang, Richard

    2008-10-01

    We have developed and operated an UV Laser-Induced Fluorescence single particle spectrometer which is capable of rapidly measuring the fluorescence emitted from individual aerosol particles, on-the-fly, as they are sampled by our sensor. Fluorescence-based detection methods have the advantage that they can deliver results in real-time and require little human labor in order to operate. We present ambient aerosol data measured in New Haven, CT, Las Cruces, NM, and Adelphi, MD. At the different locations, we find that the fluorescence characteristics of organic aerosols found remain rather similar. We also measured many different known samples in order to build a library of characteristic spectra to which we can compare the ambient data. In addition to measuring spectra from the aerosol particles, we have developed an air puffer technology which allows us to collect specific aerosol particles based on their fluorescence spectral signatures. The detection and collection of these Flourescent Bioaerosols is important as we can detect potentially harmful single airborne particles such as biowarfare agents. The research also extends to soldier health as the regional climate of Iraq is similar to that of the Chihuahuan desert where Las Cruces, NM is located.

  14. Single particle fluorescence burst analysis of epsin induced membrane fission.

    PubMed

    Brooks, Arielle; Shoup, Daniel; Kustigian, Lauren; Puchalla, Jason; Carr, Chavela M; Rye, Hays S

    2015-01-01

    Vital cellular processes, from cell growth to synaptic transmission, rely on membrane-bounded carriers and vesicles to transport molecular cargo to and from specific intracellular compartments throughout the cell. Compartment-specific proteins are required for the final step, membrane fission, which releases the transport carrier from the intracellular compartment. The role of fission proteins, especially at intracellular locations and in non-neuronal cells, while informed by the dynamin-1 paradigm, remains to be resolved. In this study, we introduce a highly sensitive approach for the identification and analysis of membrane fission machinery, called burst analysis spectroscopy (BAS). BAS is a single particle, free-solution approach, well suited for quantitative measurements of membrane dynamics. Here, we use BAS to analyze membrane fission induced by the potent, fission-active ENTH domain of epsin. Using this method, we obtained temperature-dependent, time-resolved measurements of liposome size and concentration changes, even at sub-micromolar concentration of the epsin ENTH domain. We also uncovered, at 37°C, fission activity for the full-length epsin protein, supporting the argument that the membrane-fission activity observed with the ENTH domain represents a native function of the full-length epsin protein.

  15. Single-particle and collective excitations in 62Ni

    NASA Astrophysics Data System (ADS)

    Albers, M.; Zhu, S.; Ayangeakaa, A. D.; Janssens, R. V. F.; Gellanki, J.; Ragnarsson, I.; Alcorta, M.; Baugher, T.; Bertone, P. F.; Carpenter, M. P.; Chiara, C. J.; Chowdhury, P.; David, H. M.; Deacon, A. N.; DiGiovine, B.; Gade, A.; Hoffman, C. R.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Nair, C.; Rogers, A. M.; Seweryniak, D.

    2016-09-01

    Background: Level sequences of rotational character have been observed in several nuclei in the A =60 mass region. The importance of the deformation-driving π f7 /2 and ν g9 /2 orbitals on the onset of nuclear deformation is stressed. Purpose: A measurement was performed in order to identify collective rotational structures in the relatively neutron-rich 62Ni isotope. Method: The 26Mg(48Ca,2 α 4 n γ )62Ni complex reaction at beam energies between 275 and 320 MeV was utilized. Reaction products were identified in mass (A ) and charge (Z ) with the fragment mass analyzer (FMA) and γ rays were detected with the Gammasphere array. Results: Two collective bands, built upon states of single-particle character, were identified and sizable deformation was assigned to both sequences based on the measured transitional quadrupole moments, herewith quantifying the deformation at high spin. Conclusions: Based on cranked Nilsson-Strutinsky calculations and comparisons with deformed bands in the A =60 mass region, the two rotational bands are understood as being associated with configurations involving multiple f7 /2 protons and g9 /2 neutrons, driving the nucleus to sizable prolate deformation.

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

    PubMed

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

    2016-05-01

    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.

  17. Single particle motion and gravitational measurements in magnetostatic antihydrogen traps

    NASA Astrophysics Data System (ADS)

    Zhmoginov, Andrey; Wurtele, Jonathan; Fajans, Joel; Charman, Andrew

    2012-10-01

    Recent progress in antihydrogen trapping [1-3] marks the beginning of physics measurements on neutral antimatter. One of the goals of such experiments is the observation of gravitational interaction of antimatter with matter. New methods for such measurements have been proposed, based on the statistical analysis of the temporal and spatial pattern of antihydrogen annihilations during slow (compared to bounce times) shutdowns of the mirror and octupole magnets that comprise the magnetic trap. These techniques require a thorough understanding of nonlinear dynamics of antihydrogen in magnetic traps. We apply a Hamiltonian perturbation theory to this system, analyze phase space dynamics and classify single particle orbits. The role of the stochasticity, and the Arnold diffusion accompanying it, on the accuracy of gravitational measurements is discussed. The analytical results are verified numerically, different approaches to slow particle release are compared, and implications for laser-cooling are discussed. [4pt] [1] G. B. Andresen and ALPHA Collaboration, Nature 468, 673 (2010). [2] G. B. Andresen and ALPHA Collaboration, Nature Physics 7, 558 (2011). [3] C. Amole and ALPHA Collaboration, Nature 483, 439 (2012).

  18. Characterisation of single particles from in-port ship emissions

    NASA Astrophysics Data System (ADS)

    Healy, Robert M.; O'Connor, Ian P.; Hellebust, Stig; Allanic, Arnaud; Sodeau, John R.; Wenger, John C.

    2009-12-01

    Emissions from shipping traffic may impact severely upon air quality in port cities. In this study, the size and composition of freshly emitted individual ship exhaust particles has been investigated using an aerosol time-of-flight mass spectrometer (ATOFMS) co-located with a suite of real-time instrumentation at a site in the Port of Cork, Ireland. The collected spectra were clustered using the K-means algorithm and a unique ship exhaust class containing internally mixed elemental and organic carbon, sodium, calcium, iron, vanadium, nickel and sulfate was identified. Over twenty sharp emission events were observed for this particle type during the three week measurement period in August 2008. Coincident increases in mass concentrations of sulfate, elemental carbon and particles below 2.5 μm in diameter (PM 2.5) were also observed during these events. Simultaneous scanning mobility particle sizer (SMPS) measurements indicate that the vast majority of freshly emitted ship exhaust particles lie in the ultrafine mode (<100 nm diameter). A second particle class consisted of internally mixed organic carbon, elemental carbon, ammonium and sulfate, and is tentatively attributed to aged or regionally transported ship exhaust. The results suggest that ATOFMS single particle mass spectra, when used in conjunction with other air quality monitoring instrumentation, may be useful in determining the contribution of local shipping traffic to air quality in port cities.

  19. 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

  20. Kinetics of small single particle combustion of zirconium alloy

    SciTech Connect

    Wei Haoyan; Yoo, Choong-Shik

    2012-01-15

    We present quantitative kinetic information regarding small, 1-10 {mu}m in diameter, single particle combustion of Zr-rich metal alloy foils subjected to either mechanical impacts or laser-ablation. The lights from combustion of metal fragments were recorded on a high-speed camera. The particle size was determined by the motion analysis of individual particle trajectory based on an aerodynamic drag law and further verified by the microstructure and chemical composition analysis of recovered post-burn particles. The measured particle sizes show a log-normal distribution centered at around 3.1 {mu}m in diameter, and the composition of recovered particles is that of fully oxidized ZrO{sub 2}. The temperature evolution of each particle along the space/time-trajectory is determined based on the thermal emission from combustion using a single-color photographic spectro-pyrometry. The result indicates that the particle has reached the maximum combustion temperature of 4000 K, well beyond the melting temperature of ZrO{sub 2}, and undergone the solidification of molten ZrO{sub 2} during the cooling stage. It also shows that the maximum combustion temperature decreases linearly with increasing the particle diameter, following the correlation t aD{sup 1.5-1.8} between the burn time (t) and the particle diameter (D). Combining the particle size, the burn time, and the particle temperature, both temperature and mass burn rates are obtained as a function of particle size. As the particle size increases, the temperature burn rate decreases, whereas the mass burn rate goes in the opposite direction.

  1. 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

  2. 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.

  3. 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.

  4. Single-Particle Quantum Dynamics in a Magnetic Lattice

    SciTech Connect

    Venturini, Marco

    2001-02-01

    We study the quantum dynamics of a spinless charged-particle propagating through a magnetic lattice in a transport line or storage ring. Starting from the Klein-Gordon equation and by applying the paraxial approximation, we derive a Schroedinger-like equation for the betatron motion. A suitable unitary transformation reduces the problem to that of a simple harmonic oscillator. As a result we are able to find an explicit expression for the particle wavefunction.

  5. 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.

  6. Report of the working group on single-particle nonlinear dynamics

    NASA Astrophysics Data System (ADS)

    Bazzani, A.; Bongini, L.; Corbett, J.; Dome, G.; Fedorova, A.; Freguglia, P.; Ng, K.; Ohmi, K.; Owen, H.; Papaphilippou, Y.; Robin, D.; Safranek, J.; Scandale, W.; Terebilo, A.; Turchetti, G.; Todesco, E.; Warnock, R.; Zeitlin, M.

    1999-04-01

    The Working Group on single-particle nonlinear dynamics has developed a set of tools to study nonlinear dynamics in a particle accelerator. The design of rings with large dynamic apertures is still far from automatic. The Working Group has concluded that nonlinear single-particle dynamics limits the performance of acclerators. (AIP)

  7. Multi-party quantum summation without a trusted third party based on single particles

    NASA Astrophysics Data System (ADS)

    Zhang, Cai; Situ, Haozhen; Huang, Qiong; Yang, Pingle

    We propose multi-party quantum summation protocols based on single particles, in which participants are allowed to compute the summation of their inputs without the help of a trusted third party and preserve the privacy of their inputs. Only one participant who generates the source particles needs to perform unitary operations and only single particles are needed in the beginning of the protocols.

  8. A microfluidic-based hydrodynamic trap for single particles.

    PubMed

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

    2011-01-21

    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

  9. 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.

  10. [A reading of Foucault's "The Birth of the Clinic"].

    PubMed

    Hansen, Sven Erik

    2014-01-01

    The starting point for Foucault's book was his wide reading of French medical literature from late 18th and early 19th centuries. He showed how the concept of disease changed profoundly during that period of great societal changes. Foucault's protagonists in the book were the French doctors Pinel, Bichat, Laënnec and Broussais. Here, short biographies and summaries of their works will be presented in the medical and historical context and together with extracts of Foucault's text.

  11. Ferrimagnetism and single-particle excitations in a periodic Anderson model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Seki, Kazuhiro; Shirakawa, Tomonori; Zhang, Qinfang; Li, Tao; Yunoki, Seiji

    2015-04-01

    By using the variationalcluster approximation and cluster perturbation theory, we investigate the magnetism and single-particle excitations of a periodic Anderson model on the honeycomb lattice as an effective model for the single-side hydrogenated graphene, namely, graphone. We calculate the magnetic moment as a function of U (Coulomb interaction on impurity sites) with showing that the ground state is ferrimagneticfor any U > 0. We then calculate the single-particle excitations and show that the single-particle excitations are gapless and exhibit quadratic dispersion relation near the Fermi energy.

  12. Robust upper limit of the neutron i13/2 single-particle energy

    NASA Astrophysics Data System (ADS)

    Lei, Y.; Jiang, H.

    2014-10-01

    The upper limit of the neutron i13/2 single-particle energy (ɛi13/2) is estimated in the random quasiparticle ensemble with single-particle energies. The ɛi13/2 distributions under constraints from Te134,135 and Xe136,137 spectra demonstrate that the i13/2 single-particle state can be physically mixed with the f7/2⊗3- configuration only if ɛi13/2<3 MeV. Thus, our ensemble calculation suggests a robust upper limit of 3 MeV.

  13. 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…

  14. Capacity-Communication-Power: Foucault on Contemporary Education

    ERIC Educational Resources Information Center

    Deacon, Roger

    2005-01-01

    This article explores the implications of Michel Foucault's specific references to contemporary education. Foucault developed a model for educational institutions which emphasises human capacities, communication and power relations, and which can be applied both to schools and to universities. Though he paid the closest attention to the role of…

  15. 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…

  16. 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…

  17. 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…

  18. Working Model of a Foucault Pendulum at Intermediate Latitudes

    ERIC Educational Resources Information Center

    Sears, Francis W.

    1969-01-01

    Describes a working model of a Foucault pendulum at intermediate latitudes constructed of a steel drill rod with a steel ball attached at one end. The rod makes an angle of 45 degrees with the rotation axis of a horizontal turntable. The vibrating system is the same as that which led Foucault to construct his first gravity pendulum. (LC)

  19. 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…

  20. 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…

  1. Michel Foucault on Education: A Preliminary Theoretical Overview

    ERIC Educational Resources Information Center

    Deacon, Roger

    2006-01-01

    Michel Foucault's work is already well-known in the field of education. What is not yet well-known is that Foucault's oeuvre as a whole incorporates within itself and offers for wider consumption a number of key educational themes. For purposes of clarity, these themes can be reduced to three, dealing with what might be called the past, present,…

  2. 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…

  3. Foucault, Educational Research and the Issue of Autonomy

    ERIC Educational Resources Information Center

    Olssen, Mark

    2005-01-01

    This article seeks to demonstrate a particular application of Foucault's philosophical approach to a particular issue in education: that of personal autonomy. The paper surveys and extends the approach taken by James Marshall in his book "Michel Foucault: Personal Autonomy and Education." After surveying Marshall's writing on the issue I extend…

  4. 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…

  5. 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.

  6. Four-Dimensional Spatial Nanometry of Single Particles in Living Cells Using Polarized Quantum Rods

    PubMed Central

    Watanabe, Tomonobu M.; Fujii, Fumihiko; Jin, Takashi; Umemoto, Eiji; Miyasaka, Masayuki; Fujita, Hideaki; Yanagida, Toshio

    2013-01-01

    Single particle tracking is widely used to study protein movement with high spatiotemporal resolution both in vitro and in cells. Quantum dots, which are semiconductor nanoparticles, have recently been employed in single particle tracking because of their intense and stable fluorescence. Although single particles inside cells have been tracked in three spatial dimensions (X, Y, Z), measurement of the angular orientation of a molecule being tracked would significantly enhance our understanding of the molecule’s function. In this study, we synthesized highly polarized, rod-shaped quantum dots (Qrods) and developed a coating method that optimizes the Qrods for biological imaging. We describe a Qrod-based single particle tracking technique that blends optical nanometry with nanomaterial science to simultaneously measure the three-dimensional and angular movements of molecules. Using Qrods, we spatially tracked a membrane receptor in living cells in four dimensions with precision close to the single-digit range in nanometers and degrees. PMID:23931303

  7. [The birth of acknowledgement: Michel Foucault and Werner Leibbrand].

    PubMed

    Mildenberger, Florian

    2006-01-01

    In 1964, Werner Leibbrand (1896-1974) was the first German medical historian to present, in Sudhoffs Archiv, a review of the work of Michel Foucault (1926-1984). This paper examines some of the reasons leading to the fact that Leibbrand's own generation refused to acknowledge the importance of Foucault's ideas, while, later on, younger German medical historians, although impressed with Foucault's writings, failed to acknowledge, first, the close relationship between Leibbrand's and Foucault's world views, and, second, Leibbrand's attempts at introducing Foucault to German medical historians. Leibbrand with his Jewish wife had survived the Nazi period partly in hiding. His attempts at clearing post-war German psychiatry and medical historiography of NS-sympathizers isolated him among his colleagues, many of whom had begun their career during the Third Reich. Leibbrand enjoyed the support by the Swiss medical historian and avowed Communist Erwin Ackerknecht (1906-1988), but later turned against him, possibly because Acknerknecht had called Leibbrand's writings "unscientific". Leibbrand was unable to overcome his antagonisms with his contemporaries. At the same time, opposition to Ackerknecht made him appear a respresentative of the past in the eyes of the younger generation. Thus, when Foucault was accepted by the latter, they were not prepared to examine the work of Leibbrand and realize how close some of the ideas developed by Leibbrand and Foucault had been.

  8. Using Single-Particle Motion Simulation to Optimize Coil Parameters for Inducing Autoresonant Heating in the PFRC

    NASA Astrophysics Data System (ADS)

    Liu, Jackey; Cohen, Samuel; Glasser, Alan H.; Barth, Ido; PFRC Team

    2015-11-01

    The heating of ions confined in a field-reversed configuration (FRC) equilibrium magnetic geometry subject to a small-amplitude, odd-parity rotating magnetic field (RMF) has previously been observed in single-particle Hamiltonian simulations. We consider a form of the autoresonance method to provide added heating capabilities. Two coils encircling the FRC were added near the X-points of the FRC, co-axial with the major axis; these may be used to add oscillating components, primarily to the axial field, stiffening or relaxing the field, shortening or lengthening the x-point distance. Various parameters of the simulations were modified, including the positions of the coils along the axis, the amplitude and frequency of the oscillations, as well as other FRC parameters to determine whether autoresonant heating is a feasible method for increasing ion heating. This work was support, in part, by DOE contract DE-AC02-09CH11466 and the Princeton Environmental Institute. This work is supported by the department of energy contract DE-AC02-09CH11466 as well as the Princeton Environmental Institute.

  9. 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.

  10. Single particle mass spectral signatures from vehicle exhaust particles and the source apportionment of on-line PM2.5 by single particle aerosol mass spectrometry.

    PubMed

    Yang, Jian; Ma, Shexia; Gao, Bo; Li, Xiaoying; Zhang, Yanjun; Cai, Jing; Li, Mei; Yao, Ling'ai; Huang, Bo; Zheng, Mei

    2017-09-01

    In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species. Four distinct particle types describe the majority of particles emitted by vehicle exhaust particles in this tunnel. Each particle class is labeled according to the most significant chemical features in both average positive and negative mass spectral signatures, including ECOC, NaK, Metal and PAHs species. A single particle aerosol mass spectrometry (SPAMS) was also employed during the winter of 2013 in Guangzhou to determine both the size and chemical composition of individual atmospheric particles, with vacuum aerodynamic diameter (dva) in the size range of 0.2-2μm. A total of 487,570 particles were chemically analyzed with positive and negative ion mass spectra and a large set of single particle mass spectra was collected and analyzed in order to identify the speciation. According to the typical tracer ions from different source types and classification by the ART-2a algorithm which uses source fingerprints for apportioning ambient particles, the major sources of single particles were simulated. Coal combustion, vehicle exhaust, and secondary ion were the most abundant particle sources, contributing 28.5%, 17.8%, and 18.2%, respectively. The fraction with vehicle exhaust species particles decreased slightly with particle size in the condensation mode particles. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Full control of heat transfer in single-particle structural materials

    NASA Astrophysics Data System (ADS)

    Yang, S.; Xu, L. J.; Wang, R. Z.; Huang, J. P.

    2017-09-01

    Thermal metamaterials have been applied to implement thermal phenomena, such as invisibility, illusion, and refraction. However, during the fabrication, they probably have complicated issues which are on account of the complicated structures. To get around this, here we put forward a single-particle structure. The theory helps to simplify the existing methods, which will undoubtedly contribute to the efficiency of fabrication. For clarity, we show the simulation and experimental results of thermal invisibility and illusion based on our proposed single-particle structural materials. Moreover, by tailoring the shape factor of the single particle appropriately, we can simultaneously realize thermal invisibility and illusion with only one device. The adjustable area fraction also indicates that these types of structural materials are highly adaptable. Such a single-particle device may have broad applications in misleading infrared detection. This work not only opens an avenue to design thermal materials based on single-particle structures but also holds for other physical fields like electrostatics, magnetostatics, and particle dynamics.

  12. Enhanced single-particle brightness and photostability of semiconductor polymer dots by enzymatic oxygen scavenging system

    NASA Astrophysics Data System (ADS)

    Liu, Zhihe; Yang, Yingkun; Sun, Zezhou; Wu, Changfeng

    2016-12-01

    Semiconductor polymer dots (Pdots) are emerging as an excellent fluorescent probe in biology and medicine. However, the photostability of Pdots can't meet the requirements of long term single-particle imaging and tracking applications. Here we describe the enhanced single-particle brightness and photostability of Pdots by using an efficient enzymatic oxygen scavenging system (OSS). Pdots with particle diameters of 21 nm and 43 nm (PFBT21 and PFBT43) were prepared by a nanoprecipitation method. Single-particle imaging and photobleaching were performed to investigate the effect of OSS on the per-particle brightness and photostability of Pdots. Our results indicate that the single-particle brightness of the PFBT21 Pdots in OSS was enhanced nearly two times as compare to the PFBT21 Pdots in water. The photobleaching percentages of PFBT21 and PFBT43 in OSS were determined to be 29% and 33%, respectively. These values are decreased by 2-3 times as compared to those of the same Pdots in water, indicating the significantly improved photostability of Pdots by OSS. This study provides a promising approach for enhancing photostability of Pdots in long term single-particle tracking.

  13. 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.

  14. 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.

  15. 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

  16. 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

    2012-04-04

    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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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.

  19. Progress report of the single particle irradiation system to cell (SPICE)

    NASA Astrophysics Data System (ADS)

    Imaseki, Hitoshi; Ishikawa, Takahiro; Iso, Hiroyuki; Konishi, Teruaki; Suya, Noriyoshi; Hamano, Takeshi; Wang, Xufei; Yasuda, Nakahiro; Yukawa, Masae

    2007-07-01

    At the National Institute of Radiological Sciences (NIRS), we constructed a microbeam system in 2003, the single particle irradiation to cell, SPICE. From the beginning of 2005, we redesigned it to improve the stability of the optical alignment of the system, and obtained an reduction of the beam size proportional to the vertical dimension of the object slits. As a result, SPICE is now capable of producing a beam size of approximately 10 μm diameter, and the particle numbers controllable to an intensity as low as single particles per second, and therefore a single particle irradiation facility has been successfully implemented. Moreover, these conditions can be easily reproduced with a employing a routine procedure. We describe in detail the modifications of the beam line and results, demonstrating the improvements. In addition, results from our first biological experiments are shown.

  20. [The history of the psychiatry not told by Foucault].

    PubMed

    Freitas, Fernando Ferreira Pinto de

    2004-01-01

    The article proposes a revision of the approach to madness and the birth of the psychiatric institution taken by Foucault in History of Madness. The hypothesis is that the origins of modern Psychiatry revolutionize the approach to madness by proposing it is possible to dialogue with the insane, because the madman is not someone who has lost his reason . It is hoped that this critique of Foucault's book will be a contribution to the process of psychiatric reform currently underway in Brazil.

  1. 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.

  2. 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.

  3. Neutron single-particle structure of molybdenum isotopes within the dispersive optical model

    SciTech Connect

    Bespalova, O. V. Klimochkina, A. A.; Spasskaya, T. I.

    2016-07-15

    The evolution of neutron single-particle spectra in molybdenum isotopes was calculated on the basis of the dispersive optical model over the region extending from stable isotopes to the neutron drip line. The question of how the dependence of surface absorption on the neutron–proton asymmetry and the weakening of spin–orbit interaction affect the single-particle spectra in question is studied. The results agree with the concept according to which the shell effect becomes weaker near the neutron drip line.

  4. 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.

  5. 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.

  6. Insensitivity of single particle time domain measurements to laser velocimeter 'Doppler ambiguity.'

    NASA Technical Reports Server (NTRS)

    Johnson, D. A.

    1973-01-01

    It is shown that single particle time domain measurements in high speed gas flows obtained by a laser velocimeter technique developed for use in wind tunnels are not affected by the so-called 'Doppler ambiguity.' A comparison of hot-wire anemometer and laser velocimeter measurements taken under similar flow conditions is used for the demonstration.

  7. 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.

  8. Hydrodynamic chromatography coupled with single particle-inductively coupled plasma mass spectrometry for investigating nanoparticles agglomerates.

    PubMed

    Rakcheev, Denis; Philippe, Allan; Schaumann, Gabriele E

    2013-11-19

    Studying the environmental fate of engineered or natural colloids requires efficient methods for measuring their size and quantifying them in the environment. For example, an ideal method should maintain its correctness, accuracy, reproducibility, and robustness when applied to samples contained in complex matrixes and distinguish the target particles from the natural colloidal background signals. Since it is expected that a large portion of nanoparticles will form homo- or heteroagglomerates when released into environmental media, it is necessary to differentiate agglomerates from primary particles. At present, most sizing techniques do not fulfill these requirements. In this study, we used online coupling of two promising complementary sizing techniques: hydrodynamic chromatography (HDC) and single-particle ICPMS analysis to analyze gold nanoparticles agglomerated under controlled conditions. We used the single-particle mode of the ICPMS detector to detect single particles eluted from an HDC-column and determine a mass and an effective diameter for each particle using a double calibration approach. The average agglomerate relative density and fractal dimension were calculated using these data and used to follow the morphological evolution of agglomerates over time during the agglomeration process. The results demonstrate the ability of HDC coupled to single-particle analysis to identify and characterize nanoparticle homoagglomerates and is a very promising technique for the analysis of colloids in complex media.

  9. Single-particle diffusion in dense inhomogeneous colloid suspensions in ribbon channels.

    PubMed

    Wonder, Emily; Lin, Binhua; Rice, Stuart A

    2011-10-01

    We report the results of a study of single-particle diffusion in dense colloid fluids confined in a ribbon channel geometry that is intermediate between quasione dimensional (q1D) and quasitwo dimensional (q2D). This paper complements a previous paper about pair diffusion in the same system [Phys. Rev. E 82, 031403 (2010)]. In all of the systems studied, the colloid density distribution transverse to the ribbon channel is stratified with peak amplitudes that depend on the colloid density. Although the virtual walls that confine a stratum are structured with a scale length of the colloid diameter, that structure does not have an apparent influence on the single-particle diffusion, which shows the characteristic features of diffusion in a q1D channel with smooth walls. We find that, for all channel widths and packing fractions studied, the single-particle transverse diffusion coefficient in a stratum is smaller than the single-particle longitudinal diffusion coefficient in the same stratum and that the single-particle longitudinal diffusion coefficient varies very little from stratum to stratum, being only slightly smaller in the dense strata next to the walls than in the central strata. The lack of variation in the longitudinal diffusion coefficient with apparent stratum density is explained by the application of the Fischer-Methfessel approximation to the local density in an inhomogeneous liquid. The ratio of the transverse to longitudinal diffusion coefficients varies very slowly with ribbon width, implying a very slow transition from q1D to q2D behavior.

  10. 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.

  11. 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.

  12. Scientia sexualis versus ars erotica: Foucault, van Gulik, Needham.

    PubMed

    Rocha, Leon Antonio

    2011-09-01

    This paper begins with a discussion of the scientia sexualis/ars erotica distinction, which Foucault first advances in History of Sexuality Vol. 1, and which has been employed by many scholars to do a variety of analytical work. Though Foucault has expressed his doubts regarding his conceptualization of the differences between Western and Eastern discourses of desire, he never entirely disowns the distinction. In fact, Foucault remains convinced that China must have an ars erotica. I will explore Foucault's sources of authority. To this end, I introduce the work of famous Dutch sinologist Robert Hans van Gulik, who published the tremendously influential Sexual Life in Ancient China in 1961, and also explore Joseph Needham's view on Chinese sex. I argue that, Foucault, in his fierce polemic against the "Repressive Hypothesis", himself imagined a utopian Other where pleasure and desire were organised differently. I end on a discuss on Orientalism and the project of "Sinography" of comparative literature scholars Haun Saussy, Eric Hayot and others.

  13. 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

  14. 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

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

    PubMed

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

    2014-08-01

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. 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

  17. Single particle tracking reveals biphasic transport during nanorod magnetophoresis through extracellular matrix.

    PubMed

    Mair, L O; Superfine, R

    2014-06-21

    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.

  18. 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

  19. Universal Fluctuations of Single-Particle Diffusivity in a Quenched Environment

    NASA Astrophysics Data System (ADS)

    Akimoto, Takuma; Barkai, Eli; Saito, Keiji

    2016-10-01

    Local diffusion coefficients in disordered materials such as living cells are highly heterogeneous. We consider finite systems with quenched disorder in order to investigate the effects of sample disorder fluctuations and confinement on single-particle diffusivity. While the system is ergodic in a single disorder realization, the time-averaged mean square displacement depends crucially on the disorder; i.e., the system is ergodic but non-self-averaging. Moreover, we show that the disorder average of the time-averaged mean square displacement decreases with the system size. We find a universal distribution for diffusivity in the sense that the shape of the distribution does not depend on the dimension. Quantifying the degree of the non-self-averaging effect, we show that fluctuations of single-particle diffusivity far exceed the corresponding annealed theory and also find confinement effects. The relevance for experimental situations is also discussed.

  20. Universal Fluctuations of Single-Particle Diffusivity in a Quenched Environment.

    PubMed

    Akimoto, Takuma; Barkai, Eli; Saito, Keiji

    2016-10-28

    Local diffusion coefficients in disordered materials such as living cells are highly heterogeneous. We consider finite systems with quenched disorder in order to investigate the effects of sample disorder fluctuations and confinement on single-particle diffusivity. While the system is ergodic in a single disorder realization, the time-averaged mean square displacement depends crucially on the disorder; i.e., the system is ergodic but non-self-averaging. Moreover, we show that the disorder average of the time-averaged mean square displacement decreases with the system size. We find a universal distribution for diffusivity in the sense that the shape of the distribution does not depend on the dimension. Quantifying the degree of the non-self-averaging effect, we show that fluctuations of single-particle diffusivity far exceed the corresponding annealed theory and also find confinement effects. The relevance for experimental situations is also discussed.

  1. Comparison of mineral dust and droplet residuals measured with two single particle aerosol mass spectrometers

    NASA Astrophysics Data System (ADS)

    Wonaschütz, Anna; Ludwig, Wolfgang; Zawadowicz, Maria; Hiranuma, Naruki; Hitzenberger, Regina; Cziczo, Daniel; DeMott, Paul; Möhler, Ottmar

    2017-04-01

    Single Particle mass spectrometers are used to gain information on the chemical composition of individual aerosol particles, aerosol mixing state, and other valuable aerosol characteristics. During the Mass Spectrometry Intercomparison at the Fifth Ice Nucleation (FIN-01) Workshop, the new LAAPTOF single particle aerosol mass spectrometer (AeroMegt GmbH) was conducting simultaneous measurements together with the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The aerosol particles were sampled from the AIDA chamber during ice cloud expansion experiments. Samples of mineral dust and ice droplet residuals were measured simultaneously. In this work, three expansion experiments are chosen for a comparison between the two mass spectrometers. A fuzzy clustering routine is used to group the spectra. Cluster centers describing the ensemble of particles are compared. First results show that while differences in the peak heights are likely due to the use of an amplifier in PALMS, cluster centers are comparable.

  2. 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.

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

    PubMed

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

    2012-06-19

    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 x 10(-4) in units of gravitational acceleration g.

  4. 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.

  5. 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.

  6. Single-particle parity-nonconserving matrix elements in {sup 207}Pb

    SciTech Connect

    Komives, A.; Knott, J.E.; Leuschner, M.; Szymanski, J.J.; Bowman, J.D.; Jamrisk, D.

    1993-10-01

    Measurements of the helicity dependence of neutron scattering off of heavy nuclei by the TRIPLE collaboration have yielded multiple parity-nonconserving asymmetries. The asymmetries are predominantly positive, in contradiction to the zero average asymmetry predicted by the statistical model of neutron- nucleus scattering. Theoretical calculations that explain the non-zero average asymmetry require single-particle parity- nonconserving matrix elements 10-100 times larger than those predicted by meson exchange models. We are determining the single-particle parity non-conserving mixing in {sup 207}Pb by measuring the circular polarization of the 1.064 MeV {gamma} ray. The experiment uses a transmission polarimeter and a fast data acquisition system. Initial results are presented.

  7. 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.

  8. Estimation of variance in single-particle reconstruction using the bootstrap technique.

    PubMed

    Penczek, Pawel A; Yang, Chao; Frank, Joachim; Spahn, Christian M T

    2006-05-01

    Density maps of a molecule obtained by single-particle reconstruction from thousands of molecule projections exhibit strong changes in local definition and reproducibility, as a consequence of conformational variability of the molecule and non-stoichiometry of ligand binding. These changes complicate the interpretation of density maps in terms of molecular structure. A three-dimensional (3-D) variance map provides an effective tool to assess the structural definition in each volume element. In this work, the different contributions to the 3-D variance in a single-particle reconstruction are discussed, and an effective method for the estimation of the 3-D variance map is proposed, using a bootstrap technique of sampling. Computations with test data confirm the viability, computational efficiency, and accuracy of the method under conditions encountered in practical circumstances.

  9. 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.

  10. Single-particle isomeric states in 121Pd and 117Ru

    NASA Astrophysics Data System (ADS)

    Lalkovski, S.; Bruce, A. M.; Bacelar, A. M. Denis; Górska, M.; Pietri, S.; Podolyák, Zs; Bednarczyk, P.; Caceres, L.; Casarejos, E.; Cullen, I. J.; Doornenbal, P.; Farrelly, G. F.; Garnsworthy, A. B.; Geissel, H.; Gelletly, W.; Gerl, J.; Grȩbosz, J.; Hinke, C.; Ilie, G.; Jaworski, G.; Kisyov, S.; Kojouharov, I.; Kurz, N.; Myalski, S.; Palacz, M.; Prokopowicz, W.; Regan, P. H.; Schaffner, H.; Steer, S.; Tashenov, S.; Walker, P. M.; Wollersheim, H. J.; Zhekova, M.

    2012-05-01

    Neutron-rich nuclei were populated in a relativistic fission of 238U. Gamma-rays with energies of 135 keV and 184 keV were associated with two isomeric states in 121Pd and 117Ru. Half-lives of 0.63(5) μs and 2.0(3) μs were deduced and the isomeric states were interpreted in terms of prolate deformed single-particle states.

  11. 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.

  12. Expectation values of single-particle operators in the random phase approximation ground state.

    PubMed

    Kosov, D S

    2017-02-07

    We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.

  13. Apparatus for studies of high-temperature chemical reactions in single particle systems.

    PubMed

    Andrzejak, Timothy A; Shafirovich, Evgeny; Taylor, David G; Varma, Arvind

    2007-08-01

    We report a compact microgravity flight apparatus for characterization of high-temperature chemical reactions in single particle systems. The apparatus employs an infrared CO(2) laser to ignite 1-5 mm samples while video images, thermocouple measurements, laser on/off status, and XYZ accelerometer signals are synchronously recorded. Different operating modes permit preignition quenching, ignition, and combustion experiments to be performed. The apparatus was successfully utilized during microgravity experiments on board NASA research aircraft.

  14. Single-particle dynamics of a free-electron laser with axial field

    SciTech Connect

    Pandya, T.P.; Bali, L.M.; Bakshi, U.; Jha, P.

    1987-06-15

    Single-particle dynamics of electron motion through a free-electron-laser cavity with axial guide field is presented. Equations governing the trajectories in the absence of radiation are obtained, and significant departures from the results of earlier work are discussed. Linearized gain in the presence of radiation is derived. Comparison with previous studies reveals (i) good agreement with results and (ii) gain enhancements at hitherto unreported frequencies.

  15. A deep convolutional neural network approach to single-particle recognition in cryo-electron microscopy.

    PubMed

    Zhu, Yanan; Ouyang, Qi; Mao, Youdong

    2017-07-21

    Single-particle cryo-electron microscopy (cryo-EM) has become a mainstream tool for the structural determination of biological macromolecular complexes. However, high-resolution cryo-EM reconstruction often requires hundreds of thousands of single-particle images. Particle extraction from experimental micrographs thus can be laborious and presents a major practical bottleneck in cryo-EM structural determination. Existing computational methods for particle picking often use low-resolution templates for particle matching, making them susceptible to reference-dependent bias. It is critical to develop a highly efficient template-free method for the automatic recognition of particle images from cryo-EM micrographs. We developed a deep learning-based algorithmic framework, DeepEM, for single-particle recognition from noisy cryo-EM micrographs, enabling automated particle picking, selection and verification in an integrated fashion. The kernel of DeepEM is built upon a convolutional neural network (CNN) composed of eight layers, which can be recursively trained to be highly "knowledgeable". Our approach exhibits an improved performance and accuracy when tested on the standard KLH dataset. Application of DeepEM to several challenging experimental cryo-EM datasets demonstrated its ability to avoid the selection of un-wanted particles and non-particles even when true particles contain fewer features. The DeepEM methodology, derived from a deep CNN, allows automated particle extraction from raw cryo-EM micrographs in the absence of a template. It demonstrates an improved performance, objectivity and accuracy. Application of this novel method is expected to free the labor involved in single-particle verification, significantly improving the efficiency of cryo-EM data processing.

  16. Expectation values of single-particle operators in the random phase approximation ground state

    NASA Astrophysics Data System (ADS)

    Kosov, D. S.

    2017-02-01

    We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.

  17. 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.

  18. Addressing preferred specimen orientation in single-particle cryo-EM through tilting.

    PubMed

    Tan, Yong Zi; Baldwin, Philip R; Davis, Joseph H; Williamson, James R; Potter, Clinton S; Carragher, Bridget; Lyumkis, Dmitry

    2017-08-01

    We present a strategy for tackling preferred specimen orientation in single-particle cryogenic electron microscopy by employing tilts during data collection. We also describe a tool to quantify the resulting directional resolution using 3D Fourier shell correlation volumes. We applied these methods to determine the structures at near-atomic resolution of the influenza hemagglutinin trimer, which adopts a highly preferred specimen orientation, and of ribosomal biogenesis intermediates, which adopt moderately preferred orientations.

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

    SciTech Connect

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-27

    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.

  20. 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.

  1. Advances in Single-Particle Electron Cryomicroscopy Structure Determination applied to Sub-tomogram Averaging

    PubMed Central

    Bharat, Tanmay A.M.; Russo, Christopher J.; Löwe, Jan; Passmore, Lori A.; Scheres, Sjors H.W.

    2015-01-01

    Summary Recent innovations in specimen preparation, data collection, and image processing have led to improved structure determination using single-particle electron cryomicroscopy (cryo-EM). Here we explore some of these advances to improve structures determined using electron cryotomography (cryo-ET) and sub-tomogram averaging. We implement a new three-dimensional model for the contrast transfer function, and use this in a regularized likelihood optimization algorithm as implemented in the RELION program. Using direct electron detector data, we apply both single-particle analysis and sub-tomogram averaging to analyze radiation-induced movements of the specimen. As in single-particle cryo-EM, we find that significant sample movements occur during tomographic data acquisition, and that these movements are substantially reduced through the use of ultrastable gold substrates. We obtain a sub-nanometer resolution structure of the hepatitis B capsid, and show that reducing radiation-induced specimen movement may be central to attempts at further improving tomogram quality and resolution. PMID:26256537

  2. 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.

  3. Phonon-particle coupling effects in the single-particle energies of semi-magic nuclei

    NASA Astrophysics Data System (ADS)

    Saperstein, E. E.; Baldo, M.; Pankratov, S. S.; Tolokonnikov, S. V.

    2016-11-01

    A method is presented to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei. In such nuclei, always there is a collective low-lying 2+ phonon, and a strong mixture of single-particle and particle-phonon states often occurs. As in magic nuclei the so-called g L 2 approximation, where g L is the vertex of the L-phonon creation, can be used for finding the PC correction δΣPC(ɛ) to the initial mass operator Σ0. In addition to the usual pole diagram, the phonon "tadpole" diagram is also taken into account. In semi-magic nuclei, the perturbation theory in δΣPC(ɛ) with respect to Σ0 is often invalid for finding the PC-corrected single-particle energies. Instead, the Dyson equation with the mass operator Σ(ɛ) = Σ0 + δΣPC(ɛ) is solved directly, without any use of the perturbation theory. Results for a chain of semi-magic Pb isotopes are presented.

  4. Three-dimensional reconstruction of Trypanosoma brucei editosomes using single-particle electron microscopy.

    PubMed

    Göringer, H Ulrich; Stark, Holger; Böhm, Cordula; Sander, Bjoern; Golas, Monika M

    2011-01-01

    RNA editing within the mitochondria of kinetoplastid protozoa is performed by a multicomponent -macromolecular machine known as the editosome. Editosomes are high molecular mass protein assemblies that consist of about 15-25 individual polypeptides. They bind pre-edited transcripts and convert them into translation-competent mRNAs through a biochemical reaction cycle of enzyme-catalyzed steps. At steady-state conditions, several distinct complexes can be purified from mitochondrial detergent lysates. They likely represent RNA editing complexes at different assembly stages or at different functional stages of the processing reaction. Due to their low cellular abundance, single-particle electron microscopy (EM) represents the method of choice for their structural characterization. This chapter describes a set of techniques suitable for the purification and structural characterization of RNA editing complexes by single-particle EM. The RNA editing complexes are isolated from the endogenous pool of mitochondrial complexes by tandem-affinity purification (TAP). Since the TAP procedure results in the isolation of a mixture of different RNA editing complexes, the isolates are further subjected to an isokinetic ultracentrifugation step to separate the complexes based on their sedimentation behavior. The use of the "GraFix" protocol is presented that combines mild chemical cross-linking with ultracentrifugation. Different sample preparation protocols including negative staining, cryo-negative staining, and unstained cryotechniques as well as the single-particle image processing of electron microscopical images are described.

  5. Discrimination between spheres and spheroids in a detection system for single particles based on polarization characteristics

    NASA Astrophysics Data System (ADS)

    Zhang, Hongxia; Zhai, Mengran; Sun, Jinlu; Zhou, Ye; Jia, Dagong; Liu, Tiegen; Zhang, Yimo

    2017-01-01

    The polarization characteristics of light scattered by particles are sensitive to the morphology of the scatterers. In this study, we employed the finite element method (FEM) with a finite element software (COMSOL multiphysics) to retain the potentiality to extend the theoretical study of scattering in this work to single particles with more complex morphology and arbitrary orientation. The angular distribution profiles of the scattering field components perpendicular and parallel to the incident polarization direction are obtained for spherical and spheroidal particles. By comparison with the spheres' preservation of the polarization, cross-polarization effects for differently oriented spheroidal particles are revealed. The question how to experimentally discriminate the particles with smooth surface moving freely in the detected area at single-particle level according to polarization is addressed. To this end, polarizing devices are inserted into an interference particle imaging (IPI) system. By detecting the orthogonally polarized components of the light, the preservation of the polarization state after scattering by spheres and the occurrence of cross-polarization effects after scattering by spheroids are verified experimentally with the fringes in the IPI system as a reference. A feasible method for distinguishing a spheroidal from a spherical shape at the single-particle level based on the existence of a cross-polarized component of the scattered light is proposed.

  6. Single-particle mass spectrometry of polystyrene microspheres and diamond nanocrystals.

    PubMed

    Cai, Y; Peng, W P; Kuo, S J; Lee, Y T; Chang, H C

    2002-01-01

    High-resolution mass spectra of single submicrometer-sized particles are obtained using an electrospray ionization source in combination with an audio frequency quadrupole ion-trap mass spectrometer. Distinct from conventional methods, light scattering from a continuous Ar-ion laser is detected for particles ejected out of the ion trap. Typically, 10 particles are being trapped and interrogated in each measurement. With the audio frequency ion trap operated in a mass-selective instability mode, analysis of the particles reveals that they all differ in mass-to-charge ratio (m/z), and the individual peak in the observed mass spectrum is essentially derived from one single particle. A histogram of the spectra acquired in 10(2) repetitions of the experiment is equivalent to the single spectrum that would be observed when an ion ensemble of 10(3) particles is analyzed simultaneously using the single-particle mass spectrometer (SPMS). To calibrate such single-particle mass spectra, secular frequencies of the oscillatory motions of the individual particle within the trap are measured, and the trap parameter qz at the point of ejection is determined. A mass resolution exceeding 10(4) can readily be achieved in the absence of ion ensemble effect. We demonstrate in this work that the SPMS not only allows investigations of monodisperse polystyrene microspheres, but also is capable of detecting diamond nanoparticles with a nominal diameter of 100 nm, as well.

  7. Online single particle measurement of fireworks pollution during Chinese New Year in Nanning.

    PubMed

    Li, Jingyan; Xu, Tingting; Lu, Xiaohui; Chen, Hong; Nizkorodov, Sergey A; Chen, Jianmin; Yang, Xin; Mo, Zhaoyu; Chen, Zhiming; Liu, Huilin; Mao, Jingying; Liang, Guiyun

    2017-03-01

    Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO2, coarse mode, and accumulation mode (100-500nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO3(-)) followed by an increase of sulfate peaks (97HSO4(-)+96SO4(-)) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO2 on particles. High concentration of gaseous SO2, high relative humidity and high particle loading likely promoted SO2 oxidation. Secondary nitrate formed through gas-phase oxidation of NO2 to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays. Copyright © 2016. Published by Elsevier B.V.

  8. 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

  9. Single particle electron microscopy reconstruction of the exosome complex using the random conical tilt method.

    PubMed

    Liu, Xueqi; Wang, Hong-Wei

    2011-03-28

    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

  10. The Pleasures of Learning at Work: Foucault and Phenomenology Compared

    ERIC Educational Resources Information Center

    Hughes, Christina

    2007-01-01

    This paper provides a comparative account of two conceptualisations of pleasure. The first draws on Foucault's analysis of bio-power. The second provides a phenomenological account where pleasure is viewed as an aspect of our immediate consciousness. These conceptualisations are illuminated through an analysis of employees' accounts of learning at…

  11. 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…

  12. 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.

  13. 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 theoretical…

  14. 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…

  15. Interpreting Foucault: An Evaluation of a Foucauldian Critique of Education

    ERIC Educational Resources Information Center

    Woermann, Minka

    2012-01-01

    The potential strengths and weaknesses of a Foucauldian critique of education are discussed and evaluated. The article focuses specifically on the value of Foucault's work for critiquing social and political ideologies prevalent in education, which is understood as a societal institution, and hence, as a modern regime of institutional power. In…

  16. 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'…

  17. 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…

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. 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…

  3. 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…

  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 theoretical…

  5. 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…

  6. 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'…

  7. 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…

  8. [Foucault's concept of gouvernmentality: an instrument to analyse nursing science].

    PubMed

    Friesacher, Heiner

    2004-12-01

    The following article will present the concept of gouvernmentality by the French philosopher Michel Foucault (1926-1984). I will point out in which way his idea could be applied to nursing science. The notion gouvernmentality goes back to the late works of Michel Foucault. The idea of gouvernmentality continues, broadens and shifts the stress of his influential work on the analysis of power. The strategic concept of power is not sufficient to investigate from a consistent analytical perspective into the complex problems of the state and subjectivity. Only Foucault's findings of the notion and the concept of gouvernmentality has come up to an adequate analytical method. Relations of power are investigated from the point of view and hereby social technologies and self-technologies can be analysed in relation to each other The analysis of neo-liberal gouvernmentality finally succeeds by using this broadening of perspective. A new definition of state and economy can be revealed: the market turns into a regulating principle and economics grasps all kinds of human actions and proceedings. Apart from a few exceptions the hitherto Foucault-reception in nursing science does not follow the late works of Foucault and limits its research possibilities. In this article I will analyse examples of the quality discourse and the problems of an interpretation of needs. It will be shown how both areas might shape patients as well as nurses in the sense of neo-liberal subject formation and how finally the act and art of nursing will be transformed into an act of economics.

  9. 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.

  10. Building the Nanoplasmonics Toolbox Through Shape Modeling and Single Particle Optical Studies

    NASA Astrophysics Data System (ADS)

    Ringe, Emilie

    Interest in nanotechnology is driven by unprecedented properties tailorability, achievable by controlling particle structure and composition. Unlike bulk components, minute changes in size and shape affect the optical and electronic properties of nanoparticles. Characterization of such structure-function relationships and better understanding of structure control mechanisms is crucial to the development of applications such as plasmonic sensors and devices. The objective of the current research is thus twofold: to theoretically predict and understand how shape is controlled by synthesis conditions, and to experimentally unravel, through single particle studies, how shape, composition, size, and surrounding environment affect plasmonic properties in noble metal particles. Quantitative, predictive rules and fundamental knowledge obtained from this research contributes to the "nanoplasmonics toolbox", a library designed to provide scientists and engineers the tools to create and optimize novel nanotechnology applications. In this dissertation, single particle approaches are developed and used to unravel the effects of size, shape, substrate, aggregation state and surrounding environment on the optical response of metallic nanoparticles. Ag and Au nanocubes on different substrates are first presented, followed by the discussion of the concept of plasmon length, a universal parameter to describe plasmon energy for a variety of particle shapes and plasmon modes. Plasmonic sensing (both refractive index sensing and surface-enhanced Raman spectroscopy) and polarization effects are then studied at the single particle level. In the last two Chapters, analytical shape models based on the Wulff construction provide unique modeling tools for alloy and kinetically grown nanoparticles. The former reveals a size-dependence of the shape of small alloy particles (such as those used in catalysis) because of surface segregation, while the latter uniquely models the shape of many

  11. 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.

  12. Optimal noise reduction in 3D reconstructions of single particles using a volume-normalized filter

    PubMed Central

    Sindelar, Charles V.; Grigorieff, Nikolaus

    2012-01-01

    The high noise level found in single-particle electron cryo-microscopy (cryo-EM) image data presents a special challenge for three-dimensional (3D) reconstruction of the imaged molecules. The spectral signal-to-noise ratio (SSNR) and related Fourier shell correlation (FSC) functions are commonly used to assess and mitigate the noise-generated error in the reconstruction. Calculation of the SSNR and FSC usually includes the noise in the solvent region surrounding the particle and therefore does not accurately reflect the signal in the particle density itself. Here we show that the SSNR in a reconstructed 3D particle map is linearly proportional to the fractional volume occupied by the particle. Using this relationship, we devise a novel filter (the “single-particle Wiener filter”) to minimize the error in a reconstructed particle map, if the particle volume is known. Moreover, we show how to approximate this filter even when the volume of the particle is not known, by optimizing the signal within a representative interior region of the particle. We show that the new filter improves on previously proposed error-reduction schemes, including the conventional Wiener filter as well as figure-of-merit weighting, and quantify the relationship between all of these methods by theoretical analysis as well as numeric evaluation of both simulated and experimentally collected data. The single-particle Wiener filter is applicable across a broad range of existing 3D reconstruction techniques, but is particularly well suited to the Fourier inversion method, leading to an efficient and accurate implementation. PMID:22613568

  13. 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.

  14. Two-Particle Nonlocal Aharonov-Bohm Effect from Two Single-Particle Emitters

    NASA Astrophysics Data System (ADS)

    Splettstoesser, Janine

    2010-03-01

    High-frequency single-particle emitters have been realized experimentally in the integer quantum Hall effect regime [1]: the particles are injected into edge states, operating as wave guides, and encounter splitters realized by quantum point contacts. These tools allow for the implementation of complex interferometers in mesoscopic systems showing two-particle interference effects. An example for tunable two-particle correlations is manifest in the electronic analogue of the Hong-Ou-Mandel interferometer [2], where a noise suppression is found due to the Pauli principle. In the work presented here we explore the entanglement production from two uncorrelated sources. We therefore propose a mesoscopic circuit in the quantum Hall effect regime comprising two independent single-particle sources and two distant Mach-Zehnder interferometers with magnetic fluxes. This and the tunability of the single-particle sources allow in a controllable way to produce orbitally entangled electrons [3]. Two-particle correlations appear as a consequence of erasing of which-path information due to collisions taking place at distant interferometers and in general at different times. While the current in this setup is insensitive to the magnetic flux, the two-particle correlations manifest themselves as an Aharonov-Bohm effect in the noise. In an appropriate time-interval the concurrence reaches a maximum and a Bell inequality is violated, proving the existence of time-bin entanglement.[4pt] [1] G. Fève, A. Mah'e, J.-M. Berroir, T. Kontos, B. Placais, D. C. Glattli, A. Cavanna, B. Etienne, and Y. Jin, Science 316, 1169 (2007).[0pt] [2] S. Ol'Khovskaya, J. Splettstoesser, M. Moskalets, and M. Buttiker, Phys. Rev. Lett. 101, 166802 (2008).[0pt] [3] J. Splettstoesser, M. Moskalets, and M. Buttiker, Phys. Rev. Lett.103, 076804 (2009).

  15. Using the Volta phase plate with defocus for cryo-EM single particle analysis

    PubMed Central

    Danev, Radostin; Tegunov, Dimitry; Baumeister, Wolfgang

    2017-01-01

    Previously, we reported an in-focus data acquisition method for cryo-EM single-particle analysis with the Volta phase plate (Danev and Baumeister, 2016). Here, we extend the technique to include a small amount of defocus which enables contrast transfer function measurement and correction. This hybrid approach simplifies the experiment and increases the data acquisition speed. It also removes the resolution limit inherent to the in-focus method thus allowing 3D reconstructions with resolutions better than 3 Å. DOI: http://dx.doi.org/10.7554/eLife.23006.001 PMID:28109158

  16. Wigglers and single-particle dynamics in the NLC damping rings

    SciTech Connect

    Venturini, Marco; Wolski, Andrzej; Dragt, Alex

    2003-05-06

    Wiggler insertions are expected to occupy a significant portion of the lattice of the Next Linear Collider (NLC) Main Damping Rings (MDR) and have a noticeable impact on the single-particle beam dynamics. Starting from a realistic 3D representation of the magnetic fields we calculate the transfer maps for the wigglers, accounting for linear and nonlinear effects, and we study the beam dynamics with particular attention paid to the Dynamic Aperture(DA). A DA reduction is observed but appears to remain within acceptable limits.

  17. Sugar nanowires based on cyclodextrin prepared by single particle nanofabrication technique

    NASA Astrophysics Data System (ADS)

    Watanabe, Shogo; Asano, Atsushi; Seki, Shu; Sugimoto, Masaki; Yoshikawa, Masahito; Seiichi, Tagawa; Tsukuda, Satoshi; Tanaka, Shun-Ichiro

    2009-12-01

    The direct formation of nanowires consisting of cyclodextrins by single particle nanofabrication technique (SPNT) is investigated in the present paper. Substittuted cyclodextrin (CD) derivatives and their composite with poly(4-bromostyrene) caused efficient cross-linking reaction upon irradiation, and gave nanostructures by SPNT. Successful visualization of the nanostructures by atomic force microscopy suggested drastic increase in the surface area of the materials based on CDs, leading to considerable increase in the selective adsorption efficiency of the molecules fit to the size of the hydrophobic holes of CDs.

  18. Conformational landscape of a virus by single-particle X-ray scattering

    DOE PAGES

    Hosseinizadeh, Ahmad; Mashayekhi, Ghoncheh; Copperman, Jeremy; ...

    2017-08-14

    Using a manifold-based analysis of experimental diffraction snapshots from an X-ray free electron laser, we determine the three-dimensional structure and conformational landscape of the PR772 virus to a detector-limited resolution of 9 nm. Our results indicate that a single conformational coordinate controls reorganization of the genome, growth of a tubular structure from a portal vertex and release of the genome. Furthermore, these results demonstrate that single-particle X-ray scattering has the potential to shed light on key biological processes.

  19. 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.

  20. A single particle plasmon resonance study of 3D conical nanoantennas.

    PubMed

    Schäfer, Christian; Gollmer, Dominik A; Horrer, Andreas; Fulmes, Julia; Weber-Bargioni, Alexander; Cabrini, Stefano; Schuck, P James; Kern, Dieter P; Fleischer, Monika

    2013-09-07

    Metallic nanocones are well-suited optical antennas for near-field microscopy and spectroscopy, exhibiting a number of different plasmonic modes. A major challenge in using nanocones for many applications is maximizing the signal at the tip while minimizing the background from the base. It is shown that nanocone plasmon resonance properties can be shifted over a wide range of wavelengths by variation of the substrate, material, size and shape, enabling potential control over specific modes and field distributions. The individual resonances are identified and studied by correlated single particle dark field scattering and scanning electron microscopy in combination with numerical simulations.

  1. Two-particle nonlocal Aharonov-Bohm effect from two single-particle emitters.

    PubMed

    Splettstoesser, Janine; Moskalets, Michael; Büttiker, Markus

    2009-08-14

    We propose a mesoscopic circuit in the quantum Hall effect regime comprising two uncorrelated single-particle sources and two distant Mach-Zehnder interferometers with magnetic fluxes, which allows us in a controllable way to produce orbitally entangled electrons. Two-particle correlations appear as a consequence of erasing of which-path information due to collisions taking place at distant interferometers and in general at different times. The two-particle correlations manifest themselves as an Aharonov-Bohm effect in noise, while the current is insensitive to magnetic fluxes. In an appropriate time interval the concurrence reaches a maximum and a Bell inequality is violated.

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

    PubMed Central

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

    2016-01-01

    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

  3. Correlation effects in single-particle overlap functions and one-nucleon removal reactions

    NASA Astrophysics Data System (ADS)

    Gaidarov, M. K.; Pavlova, K. A.; Dimitrova, S. S.; Stoitsov, M. V.; Antonov, A. N.; van Neck, D.; Müther, H.

    1999-08-01

    Single-particle overlap functions and spectroscopic factors are calculated on the basis of the one-body density matrices (ODM) obtained for the nucleus 16O employing different approaches to account for the effects of correlations. The calculations use the relationship between the overlap functions related to bound states of the (A-1)-particle system and the ODM for the ground state of the A-particle system. The resulting bound-state overlap functions are compared and tested in the description of the experimental data from (p,d) reactions for which the shape of the overlap function is important.

  4. Effect of Single Particle Hopping and Out of Plane Magnetic Impurity on Coupled Planar Superconductors

    NASA Astrophysics Data System (ADS)

    Sardar, Manas; Sa, Debanand

    It is shown that the single particle band motion along the c axis is harmful for superconductivity in anisotropic systems. Variation of Tc with c axis hopping parameter is shown for both the conventional Josephson coupled, planar superconductors and for interlayer pair tunneling mechanism of Wheatley, Hsu, and Anderson (WHA). Effect of out-of-plane magnetic impurity substitution is shown to suppress Tc more for conventional superconductors whereas there is a very sharp decrease of Tc in the WHA mechanism at larger concentrations.

  5. 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. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Hedgehog-Like Upconversion Crystals: Controlled Growth and Molecular Sensing at Single-Particle Level.

    PubMed

    Liu, Xiaowang; Li, Xiyan; Qin, Xian; Xie, Xiaoji; Huang, Ling; Liu, Xiaogang

    2017-10-01

    Topological control of nanostructures plays a crucial role in understanding the crystal growth process at the nanometer length scale. Here, the scalable synthesis of upconversion materials with distinct hedgehog-like morphologies by a seed-mediated synthetic procedure is reported. It is demonstrated that a close match in the crystal lattice between the core and shell components is essential for synthesizing such hierarchical nanostructures. These optical nanomaterials also enable the development of a single-particle-based platform for high-sensitivity molecular sensing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. FAST WAVELET-BASED SINGLE-PARTICLE RECONSTRUCTION IN CRYO-EM.

    PubMed

    Vonesch, Cédric; Wang, Lanhui; Shkolnisky, Yoel; Singer, Amit

    2011-06-09

    This paper presents a novel algorithm for the 3D tomographic inversion problem that arises in single-particle electron cryo-microscopy (Cryo-EM). It is based on two key components: 1) a variational formulation that promotes sparsity in the wavelet domain and 2) the Toeplitz structure of the combined projection/back-projection operator. The first idea has proven to be very effective for the recovery of piecewise-smooth signals, which is confirmed by our numerical experiments. The second idea allows for a computationally efficient implementation of the reconstruction procedure, using only one circulant convolution per iteration.

  8. SPIDER image processing for single-particle reconstruction of biological macromolecules from electron micrographs

    PubMed Central

    Shaikh, Tanvir R; Gao, Haixiao; Baxter, William T; Asturias, Francisco J; Boisset, Nicolas; Leith, Ardean; Frank, Joachim

    2009-01-01

    This protocol describes the reconstruction of biological molecules from the electron micrographs of single particles. Computation here is performed using the image-processing software SPIDER and can be managed using a graphical user interface, termed the SPIDER Reconstruction Engine. Two approaches are described to obtain an initial reconstruction: random-conical tilt and common lines. Once an existing model is available, reference-based alignment can be used, a procedure that can be iterated. Also described is supervised classification, a method to look for homogeneous subsets when multiple known conformations of the molecule may coexist. PMID:19180078

  9. Carbon Nanotube-Quantum Dot Nanohybrids: Coupling with Single-Particle Control in Aqueous Solution.

    PubMed

    Attanzio, Antonio; Sapelkin, Andrei; Gesuele, Felice; van der Zande, Arend; Gillin, William P; Zheng, Ming; Palma, Matteo

    2017-02-10

    A strategy is reported for the controlled assembly of organic-inorganic heterostructures consisting of individual single-walled carbon nanotubes (SWCNTs) selectively coupled to single semiconductor quantum dots (QDs). The assembly in aqueous solution was controlled towards the formation of monofunctionalized SWCNT-QD structures. Photoluminescence studies in solution, and on surfaces at the single nanohybrid level, showed evidence of electronic coupling between the two nanostructures. The ability to covalently couple heterostructures with single particle control is crucial for the design of novel QD-based optoelectronic and light-energy conversion devices.

  10. Conformational landscape of a virus by single-particle X-ray scattering.

    PubMed

    Hosseinizadeh, Ahmad; Mashayekhi, Ghoncheh; Copperman, Jeremy; Schwander, Peter; Dashti, Ali; Sepehr, Reyhaneh; Fung, Russell; Schmidt, Marius; Yoon, Chun Hong; Hogue, Brenda G; Williams, Garth J; Aquila, Andrew; Ourmazd, Abbas

    2017-09-01

    Using a manifold-based analysis of experimental diffraction snapshots from an X-ray free electron laser, we determine the three-dimensional structure and conformational landscape of the PR772 virus to a detector-limited resolution of 9 nm. Our results indicate that a single conformational coordinate controls reorganization of the genome, growth of a tubular structure from a portal vertex and release of the genome. These results demonstrate that single-particle X-ray scattering has the potential to shed light on key biological processes.

  11. 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.

  12. Advances in the field of single-particle cryo-electron microscopy over the last decade.

    PubMed

    Frank, Joachim

    2017-02-01

    In single-particle cryo-electron microscopy (cryo-EM), molecules suspended in a thin aqueous layer are rapidly frozen and imaged at cryogenic temperature in the transmission electron microscope. From the random projection views, a three-dimensional image is reconstructed, enabling the structure of the molecule to be obtained. In this article I discuss technological progress over the past decade, which has, in my own field of study, culminated in the determination of ribosome structure at 2.5-Å resolution. I also discuss likely future improvements in methodology.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Single-Particle Cryo-EM of the Ryanodine Receptor Channel in an Aqueous Environment

    PubMed Central

    Baker, Mariah R.; Fan, Guizhen

    2015-01-01

    Ryanodine receptors (RyRs) are tetrameric ligand-gated Ca2+ release channels that are responsible for the increase of cytosolic Ca2+ concentration leading to muscle contraction. Our current understanding of RyR channel gating and regulation is greatly limited due to the lack of a high-resolution structure of the channel protein. The enormous size and unwieldy shape of Ca2+ release channels make X-ray or NMR methods difficult to apply for high-resolution structural analysis of the full-length functional channel. Single-particle electron cryo-microscopy (cryo-EM) is one of the only effective techniques for the study of such a large integral membrane protein and its molecular interactions. Despite recent developments in cryo-EM technologies and break-through single-particle cryo-EM studies of ion channels, cryospecimen preparation, particularly the presence of detergent in the buffer, remains the main impediment to obtaining atomic-resolution structures of ion channels and a multitude of other integral membrane protein complexes. In this review we will discuss properties of several detergents that have been successfully utilized in cryo-EM studies of ion channels and the emergence of the detergent alternative amphipol to stabilize ion channels for structure-function characterization. Future structural studies of challenging specimen like ion channels are likely to be facilitated by cryo-EM amenable detergents or alternative surfactants. PMID:26913144

  18. Single-particle cryo-EM of the ryanodine receptor channel in an aqueous environment

    PubMed Central

    Baker, Mariah R.; Fan, Guizhen; Serysheva, Irina I.

    2015-01-01

    Ryanodine receptors (RyRs) are tetrameric ligand-gated Ca2+ release channels that are responsible for the increase of cytosolic Ca2+ concentration leading to muscle contraction. Our current understanding of RyR channel gating and regulation is greatly limited due to the lack of a high-resolution structure of the channel protein. The enormous size and unwieldy shape of Ca2+ release channels make X-ray or NMR methods difficult to apply for high-resolution structural analysis of the full-length functional channel. Single-particle electron cryo-microscopy (cryo-EM) is one of the only effective techniques for the study of such a large integral membrane protein and its molecular interactions. Despite recent developments in cryo-EM technologies and break-through single-particle cryo-EM studies of ion channels, cryospecimen preparation, particularly the presence of detergent in the buffer, remains the main impediment to obtaining atomic-resolution structures of ion channels and a multitude of other integral membrane protein complexes. In this review we will discuss properties of several detergents that have been successfully utilized in cryo-EM studies of ion channels and the emergence of the detergent alternative amphipol to stabilize ion channels for structure-function characterization. Future structural studies of challenging specimen like ion channels are likely to be facilitated by cryo-EM amenable detergents or alternative surfactants. PMID:25844145

  19. Massively parallel unsupervised single-particle cryo-EM data clustering via statistical manifold learning

    PubMed Central

    Wu, Jiayi; Ma, Yong-Bei; Congdon, Charles; Brett, Bevin; Chen, Shuobing; Xu, Yaofang; Ouyang, Qi

    2017-01-01

    Structural heterogeneity in single-particle cryo-electron microscopy (cryo-EM) data represents a major challenge for high-resolution structure determination. Unsupervised classification may serve as the first step in the assessment of structural heterogeneity. However, traditional algorithms for unsupervised classification, such as K-means clustering and maximum likelihood optimization, may classify images into wrong classes with decreasing signal-to-noise-ratio (SNR) in the image data, yet demand increased computational costs. Overcoming these limitations requires further development of clustering algorithms for high-performance cryo-EM data processing. Here we introduce an unsupervised single-particle clustering algorithm derived from a statistical manifold learning framework called generative topographic mapping (GTM). We show that unsupervised GTM clustering improves classification accuracy by about 40% in the absence of input references for data with lower SNRs. Applications to several experimental datasets suggest that our algorithm can detect subtle structural differences among classes via a hierarchical clustering strategy. After code optimization over a high-performance computing (HPC) environment, our software implementation was able to generate thousands of reference-free class averages within hours in a massively parallel fashion, which allows a significant improvement on ab initio 3D reconstruction and assists in the computational purification of homogeneous datasets for high-resolution visualization. PMID:28786986

  20. Protein secondary structure determination by constrained single-particle cryo-electron tomography.

    PubMed

    Bartesaghi, Alberto; Lecumberry, Federico; Sapiro, Guillermo; Subramaniam, Sriram

    2012-12-05

    Cryo-electron microscopy (cryo-EM) is a powerful technique for 3D structure determination of protein complexes by averaging information from individual molecular images. The resolutions that can be achieved with single-particle cryo-EM are frequently limited by inaccuracies in assigning molecular orientations based solely on 2D projection images. Tomographic data collection schemes, however, provide powerful constraints that can be used to more accurately determine molecular orientations necessary for 3D reconstruction. Here, we propose "constrained single-particle tomography" as a general strategy for 3D structure determination in cryo-EM. A key component of our approach is the effective use of images recorded in tilt series to extract high-resolution information and correct for the contrast transfer function. By incorporating geometric constraints into the refinement to improve orientational accuracy of images, we reduce model bias and overrefinement artifacts and demonstrate that protein structures can be determined at resolutions of ∼8 Å starting from low-dose tomographic tilt series.

  1. Pairing in the BCS and LN approximations using continuum single particle level density

    NASA Astrophysics Data System (ADS)

    Id Betan, R. M.; Repetto, C. E.

    2017-04-01

    Understanding the properties of drip line nuclei requires to take into account the correlations with the continuum spectrum of energy of the system. This paper has the purpose to show that the continuum single particle level density is a convenient way to consider the pairing correlation in the continuum. Isospin mean-field and isospin pairing strength are used to find the Bardeen-Cooper-Schrieffer (BCS) and Lipkin-Nogami (LN) approximate solutions of the pairing Hamiltonian. Several physical properties of the whole chain of the Tin isotope, as gap parameter, Fermi level, binding energy, and one- and two-neutron separation energies, were calculated and compared with other methods and with experimental data when they exist. It is shown that the use of the continuum single particle level density is an economical way to include explicitly the correlations with the continuum spectrum of energy in large scale mass calculation. It is also shown that the computed properties are in good agreement with experimental data and with more sophisticated treatment of the pairing interaction.

  2. 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.

  3. Laboratory and Ambient Studies Using an Automated Semi-Continuous Single-Particle Aerosol Raman Spectrometer

    NASA Astrophysics Data System (ADS)

    Doughty, D., III; Hill, S. C.

    2015-12-01

    Single-particle Raman spectra can yield extensive information about in-situ ambient particulate composition. However, Raman spectral measurements of individual aerosol particles typically require collection of samples in the field followed by offline Raman spectral measurements in a laboratory. The process requires considerable operator time. We report results obtained with an automated, single-particle Aerosol Raman Spectrometer built by Battelle, which is the core of Battelle's Resource Effective Bioidentification System (REBS). This instrument collects aerosol particles onto a metallized polymer tape and simultaneously measures Raman spectra of particles obtained during the previous collection period. At the end of each collection period (typically 15 minutes), the tape is advanced and the next collection and measurement period is begun. In this way, particles are semi-continuously sampled and their Raman spectra are measured. We show laboratory data from different sizes of polystyrene latex spheres. We also show results from calcium sulfate particles, vehicular emission soot, and other particles. We discuss the influence of imaging time on the quality of the Raman spectra measured and on the ability of the instrument to resolve aerosol particles. Finally, we present results from an outdoor sampling period during the summer of 2015 where the instrument ran unattended for more than one week collecting particles and measuring their Raman spectra. We suggest that the routine use of such an automated particle-sampling instrument should increase our understanding of inorganic and organic aerosols including biological aerosols and sources and fates of these particles.

  4. An adaptation of the Wiener filter suitable for analyzing images of isolated single particles

    PubMed Central

    Sindelar, Charles V.; Grigorieff, Nikolaus

    2011-01-01

    The Wiener filter is a standard means of optimizing the signal in sums of aligned, noisy images obtained by electron cryo-microscopy (cryo-EM). However, estimation of the resolution-dependent (“spectral”) signal-to-noise ratio (SSNR) from the input data has remained problematic, and error reduction due to specific application of the SSNR term within a Wiener filter has not been reported. Here we describe an adjustment to the Wiener filter for optimal summation of images of isolated particles surrounded by large regions of featureless background, as is typically the case in single-particle cryo-EM applications. We show that the density within the particle area can be optimized, in the least-squares sense, by scaling the SSNR term found in the conventional Wiener filter by a factor that reflects the fraction of the image field occupied by the particle. We also give related expressions that allow the SSNR to be computed for application in this new filter, by incorporating a masking step into a Fourier Ring Correlation (FRC), a standard resolution measure. Furthermore, we show that this masked FRC estimation scheme substantially improves on the accuracy of conventional SSNR estimation methods. We demonstrate the validity of our new approach in numeric tests with simulated data corresponding to realistic cryo-EM imaging conditions. This variation of the Wiener filter and accompanying derivation should prove useful for a variety of single-particle cryo-EM applications, including 3D reconstruction. PMID:21757012

  5. Fourier transforms of single-particle wave functions in cylindrical coordinates

    NASA Astrophysics Data System (ADS)

    Rizea, M.; Carjan, N.

    2016-12-01

    A formalism and the corresponding numerical procedures that calculate the Fourier transform of a single-particle wave function defined on a grid of cylindrical (ρ, z) coordinates is presented. Single-particle states in spherical and deformed nuclei have been chosen in view of future applications in the field of nuclear reactions. Bidimensional plots of the probability that the nucleon's momentum has a given value K=√{k_{ρ}2+kz2} are produced and from them the K -distributions are deduced. Three potentials have been investigated: a) a sharp surface spherical well ( i.e., of constant depth), b) a spherical Woods-Saxon potential i.e., diffuse surface) and c) a deformed potential of Woods-Saxon type. In the first case the momenta are as well defined as allowed by the uncertainty principle. Depending on the state, their distributions have up to three separated peaks as a consequence of the up to three circular ridges of the bidimensional probabilities plots. In the second case the diffuseness allows very low momenta to be always populated thus creating tails towards the origin ( K = 0). The peaks are still present but not well separated. In the third case the deformation transforms the above mentioned circular ridges into ellipses thus spreading the K-values along them. As a consequence the K-distributions have only one broad peak.

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

    DOE PAGES

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

    2015-02-09

    Organometallic halide perovskites 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

  7. 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.

  8. A Single Particle Soot Photometer for the Measurement of Aerosol Black Carbon

    NASA Astrophysics Data System (ADS)

    Kok, G. L.; Baumgardner, D.; Spuler, S.

    2002-12-01

    A Single Particle Soot Photometer (SP2) has been developed for the measurement of black carbon mass in single particles. The analytical technique is the incandescence of light absorbing particles. An aerosol stream is directed intra-cavity across the beam of a Nd:YAG laser where the laser intensity is in excess of 1 MW/cm2. Non-light absorbing particles only scatter light but particles containing black carbon absorb sufficient energy to heat and incandesce as they vaporize. Four optical detectors are used to measure the scattered and incandescence radiation from the particles. One measures the scattered, 1064 nm radiation while the other three detectors measure the light of incandescence over different wavelength regions. The ratio of intensities at the different wavelengths yields the temperature at which the particle incandesced whereas the absolute intensity is proportional to the carbon mass. The minimum size of non-incandescing particles that can be measured is approximately 100 nm and for incandescing particles it is 80 nm. Data will be presented on the operation of the instrumentation and examples of ambient measurements of black carbon.

  9. Cryo-electron microscopy single particle reconstruction of virus particles using compressed sensing theory

    NASA Astrophysics Data System (ADS)

    Kim, Min Woo; Choi, Jiyoung; Yu, Liu; Lee, Kyung Eun; Han, Sung-Sik; Ye, Jong Chul

    2007-02-01

    Sparse object supports are often encountered in many imaging problems. For such sparse objects, recent theory of compressed sensing tells us that accurate reconstruction of objects are possible even from highly limited number of measurements drastically smaller than the Nyquist sampling limit by solving L I minimization problem. This paper employs the compressed sensing theory for cryo-electron microscopy (cryo-EM) single particle reconstruction of virus particles. Cryo-EM single particle reconstruction is a nice application of the compressed sensing theory because of the following reasons: 1) in some cases, due to the difficulty in sample collection, each experiment can obtain micrographs with limited number of virus samples, providing undersampled projection data, and 2) the nucleic acid of a viron is enclosed within capsid composed of a few proteins; hence the support of capsid in 3-D real space is quite sparse. In order to minimize the L I cost function derived from compressed sensing, we develop a novel L I minimization method based on the sliding mode control theory. Experimental results using synthetic and real virus data confirm that the our algorithm provides superior reconstructions of 3-D viral structures compared to the conventional reconstruction algorithms.

  10. Sensitive sandwich immunoassay based on single particle mode inductively coupled plasma mass spectrometry detection.

    PubMed

    Liu, Rui; Xing, Zhi; Lv, Yi; Zhang, Sichun; Zhang, Xinrong

    2010-11-15

    A sensitive sandwich type immunoassay has been proposed with the detection by inductively coupled plasma mass spectrometry (ICP-MS) in a single particle mode (time resolved analysis). The signal induced by the flash of ions ((197)Au(+)) due to the ionization of single Au-nanoparticle (Au-NP) label in the plasma torch can be measured by the mass spectrometer. The frequency of the transient signals is proportional to the concentration of Au-NPs labels. Characteristics of the signals obtained from Au-NPs of 20, 45 and 80 nm in diameters were discussed. The analytical figures for the determination of Au-labeled IgG using ICP-MS in conventional integral mode and single particle mode were compared in detail. Rabbit-anti-human IgG was used as a model analyte in the sandwich immunoassay. A detection limit (3 σ) of 0.1 ng mL(-1) was obtained for rabbit-anti-human IgG after immunoreactions, with a linear range of 0.3-10 ng mL(-1) and a RSD of 8.1% (2.0 ng mL(-1)). Finally, the proposed method was successfully applied to spiked rabbit-anti-human IgG samples and rabbit-anti-human serum samples. The method resulted to be a highly sensitive ICP-MS based sandwich type immunoassay.

  11. Protein Secondary Structure Determination by Constrained Single-Particle Cryo-Electron Tomography

    PubMed Central

    Bartesaghi, Alberto; Lecumberry, Federico; Sapiro, Guillermo; Subramaniam, Sriram

    2012-01-01

    SUMMARY Cryo-electron microscopy (cryo-EM) is a powerful technique for 3D structure determination of protein complexes by averaging information from individual molecular images. The resolutions that can be achieved with single-particle cryo-EM are frequently limited by inaccuracies in assigning molecular orientations based solely on 2D projection images. Tomographic data collection schemes, however, provide powerful constraints that can be used to more accurately determine molecular orientations necessary for 3D reconstruction. Here, we propose “constrained single-particle tomography” as a general strategy for 3D structure determination in cryo-EM. A key component of our approach is the effective use of images recorded in tilt series to extract high-resolution information and correct for the contrast transfer function. By incorporating geometric constraints into the refinement to improve orientational accuracy of images, we reduce model bias and overrefinement artifacts and demonstrate that protein structures can be determined at resolutions of ~8 Å starting from low-dose tomographic tilt series. PMID:23217682

  12. 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.

  13. 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

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

    PubMed

    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.

  15. 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.

  16. Single particle cryo-electron microscopy and 3-D reconstruction of viruses.

    PubMed

    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.

  17. Thorium colloid analysis by single particle inductively coupled plasma-mass spectrometry.

    PubMed

    Degueldre, C; Favarger, P-Y

    2004-04-19

    Thorium colloid analysis in water has been carried out by a single particle mode using inductively coupled plasma mass spectrometry (ICP-MS). The flash of ions due to the ionisation of a thorium colloidal particle in the plasma torch can be detected and measured in a time scan for (232)Th (+ ) or (248)[ThO] (+ ) according to the sensitivity required by the mass spectrometer. The peaks of the recorded intensity of the MS signal can be analysed as a function of the particle size or fraction of the studied element in the colloid phase. The frequency of the flashes is directly proportional to the concentration of particles in the colloidal suspension. After discussing Th colloid detection, on the basis of the intensity of the ion flashes generated in the plasma torch, tests were performed on thorium dioxide colloidal particles. This feasibility study also describes the experimental conditions and the limitation of the plasma design to detect thorium colloids in a single particle analysis mode down to about 10fg.

  18. Single-particle characterization of summertime arctic aerosols collected at Ny-Alesund, Svalbard.

    PubMed

    Geng, Hong; Ryu, Jiyeon; Jung, Hae-Jin; Chung, Hyeok; Ahn, Kang-Ho; Ro, Chul-Un

    2010-04-01

    Single-particle characterization of summertime Arctic aerosols is useful to understand the impact of air pollutants on the polar atmosphere. In the present study, a quantitative single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was used to characterize 8100 individual particles overall in 16 sets of aerosol samples collected at Ny-Alesund, Svalbard, Norway on 25-31 July, 2007. Based on their X-ray spectral and secondary electron image data of individual particles, 13 particle types were identified, in which particles of marine origin were the most abundant, followed by carbonaceous and mineral dust particles. A number of aged (reacted) sea salt (and mixture) particles produced by the atmospheric reaction of genuine sea-salts, especially with NO(x) or HNO(3), were significantly encountered in almost all the aerosol samples. They greatly outnumbered genuine sea salt particles, implying that the summertime Arctic atmosphere, generally regarded as a clean background environment, is disturbed by anthropogenic air pollutants. The main sources of airborne NO(x) (or HNO(3)) are probably ship emissions around the Arctic Ocean, industry emission from northern Europe and northwestern Siberia, and renoxification of NO(3)(-) within or on the melting snow/ice surface.

  19. Maskiton: Interactive, web-based classification of single-particle electron microscopy images.

    PubMed

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

    2013-05-01

    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.

  20. Silver Nanoflowers for Single-Particle SERS with 10 pM Sensitivity.

    PubMed

    Roy, Shrawan; Ajmal, C Muhammed; Baik, Seunghyun; Kim, Jeongyong

    2017-09-13

    Surface-enhanced Raman scattering (SERS) has received considerable attention as a noninvasive optical sensing technique with ultrahigh sensitivity. While numerous types of metallic particles have been actively investigated as SERS substrates, the development of new SERS agents with high sensitivity and their reliable characterization are still required. Here we report the preparation and characterization of flower-shaped silver (Ag) nanoparticles that exhibit high-sensitivity single-particle SERS performance. Ag nanoflowers (NFs) with bud sizes in the range 220~620 nm were synthesized by the wet synthesis method. The densely packed nanoscale petals with thicknesses in the range 9~22 nm exhibit a large number of hot spots that significantly enhance their plasmonic activity. A single Ag NF particle (530~620 nm) can detect as little as 10<sup>-11</sup> M 4-mercaptobenzoic acid, and thus provides a sensitivity three orders of SERS magnitude greater than that of a spherical Ag nanoparticle. The analytical enhancement factors (AEFs) for single Ag NF particles were found to be as high as 8.0x10<sup>9</sup>, providing unprecedented high SERS detectivity at the single particle level. Here we present an unambiguous and systematic assessment of the SERS performances of the Ag NFs and demonstrate that they provide highly sensitive sensing platforms by single SERS particle. © 2017 IOP Publishing Ltd.

  1. Single particle tracking reveals spatial and dynamic organization of the E. coli biofilm matrix.

    PubMed

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

    2014-08-27

    Biofilms are communities of surface-adherent bacteria surrounded by secreted polymers known as the extracellular polymeric substance (EPS). 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.

  2. 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.

  3. 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.

  4. Effect of single-particle splitting in the exact wave function of the isovectorial pairing Hamiltonian

    SciTech Connect

    Lerma H, S.

    2010-07-15

    The structure of the exact wave function of the isovectorial pairing Hamiltonian with nondegenerate single-particle levels is discussed. The way that the single-particle splittings break the quartet condensate solution found for N=Z nuclei in a single degenerate level is established. After a brief review of the exact solution, the structure of the wave function is analyzed and some particular cases are considered where a clear interpretation of the wave function emerges. An expression for the exact wave function in terms of the isospin triplet of pair creators is given. The ground-state wave function is analyzed as a function of pairing strength, for a system of four protons and four neutrons. For small and large values of the pairing strength a dominance of two-pair (quartets) scalar couplings is found, whereas for intermediate values enhancements of the nonscalar couplings are obtained. A correlation of these enhancements with the creation of Cooper-like pairs is observed.

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

    PubMed

    Cianfrocco, Michael A; Leschziner, Andres E

    2015-05-08

    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.

  6. 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.

  7. Between exclusion and emancipation: Foucault's ethics and disability.

    PubMed

    Pezdek, Krzysztof; Rasiński, Lotar

    2017-04-01

    The aim of the study was to demonstrate how Foucault's ethics, which we understand as a tension between exclusion and emancipation, helps both critically reassess two disability models that prevail in the contemporary literature concerning disability, that is the medical model and the social one, and support and inspire an ethical project of including people with disabilities in spheres of life from which they have been excluded by various power/knowledge regimes. We claim, following Foucault, that such a project should be informed by critical reflection on exclusion-generating forms of knowledge about people with disabilities and focused on individual ethical actions fostering self-realization and emancipation of people with disability.

  8. 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.

  9. 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.

  10. Testing of flat optical surfaces by the quantitative Foucault method.

    PubMed

    Simon, M C; Simon, J M

    1978-01-01

    The complete theory of measurement of optical flat mirrors of circular or elliptical shape using the quantitative Foucault method is described here. It has been used in Córdoba since 1939 in a partially intuitive but correct form. The surface, not yet flat and, at times, astigmatic, is assimilated to the sum of a spherical plus a cylindrical dome. The errors of the three possible ways of reckoning are calculated.

  11. [Sexuality according to Michel Foucault: a contribution to nursing].

    PubMed

    Ribeiro, M O

    1999-12-01

    The author develops a reflexion about Foucault conception in relation to the "sexuality dispositive" that has been presented in the book "Microfísica do Poder". She tries to rescue, through this classic literature, a historic and social point of view in the practice of nursing, without missing the actual concepts that deppreciate the affection of the personal relations to overvalue the masculine virility, converting the pleasure a consumer goods and a goal in itself.

  12. A new coincidence model for single particle counters, Part II: Advances and applications.

    PubMed

    Knapp, J Z; Lieberman, A; Abramson, L R

    1994-01-01

    Accuracy, acceptance limits and methods for U.S.P. (788) contaminating particle assays published in the XXII Revision are refined in U.S.P. XXIII. In both Revisions, although different numerical values and methods are employed, particle contamination limits remain constants for all S.V.I. container volumes. The effect of this quality standard is high particle concentration acceptance limits in the smallest S.V.I. container sizes. The effect of these high concentrations is to introduce both undercount errors and false counts into U.S.P. (788) SVI contaminating particle assays. There is general agreement that the count of high concentrations of particles by a single particle light extinction counter result in an increase of the average size of the distribution of particles reported and a decrease in their total number. The error mechanism is termed "signal coincidence." Understanding and control of both these problems is unified with the introduction of the count efficiency parameter. Part I of this paper makes available two core concepts with which evaluation and control of coincidence error in single particle counters can be accurately quantified. These two core concepts are the "Particle Triggered Poisson Model," a new more accurate statistical model of the particle counting process and a concentration measure that includes the effect of particle size on the counting capability of a detector. Use of these concepts make it possible to evaluate particle detector count efficiency capability from experimental data of the coincidence effect. This is an application paper. It combines the theory in the Part I paper with the replicability of particle counters into a simple test protocol. The test results can be used to calculate a contour of particle size and count within which both undercount errors and the introduction of false counts into U.S.P. (788) particle assays are controlled. From the data analyzed it can be seen that any single particle size test cannot

  13. 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.

  14. The power behind empowerment for staff nurses: using Foucault's concepts.

    PubMed

    Udod, Sonia A

    2008-01-01

    The concept of staff nurse empowerment is often evoked in dialogue concerning the nature of nurses' practice in improving their work environments. Nurse empowerment has been the subject of vigorous discussion in healthcare settings, and has been researched largely through an organizational perspective. In this paper, nurse empowerment is analyzed by drawing upon a critical science approach as an alternative theoretical lens. Power is integral to empowerment, and occurs in the context of relations of power. The author uses the ideas of Michel Foucault to address the different ways in which power relations shape nurses' experiences in the workplace. Foucault conceptualizes power as a form of power that envelops staff nurses and nurse managers and, more specifically, as a set of disciplinary techniques. Rather than discussing power solely as a repressive force, Foucault identifies the productive aspects of power. His analysis of where power resides suggests a thought-provoking approach to staff nurse empowerment that has the potential to change nurses' practice through points of resistance, and thus has implications for improving the quality of nurses' work life.

  15. [Michel Foucault and the persistence of psychiatric power].

    PubMed

    Caponi, Sandra

    2009-01-01

    This article aims studying the course held by Michel Foucault at the Collège de France in 1973-1974. The records of this course were published in 2003 under the name ' Psychiatric power' . The objective was to compare the different ways in which Foucault analyzes the question of madness in ' Psychiatric power' and in ' History of Madness in the Classical Age' (1961). It is a comparative study about the different ways of analyzing madness developed by Michel Foucault during the archeological and genealogic periods of his work. The absence of the body; binary diagnosis; the description of the surface of symptoms; the classification of diseases more similar to the botanical classification than to pathology; the process of cure directly linked to restitution of behaviors and moral values; as well as the over-power of the psychiatrist, seem to speak about the persistence of an old model of power, a pre-modern and pre-capitalist model, a residue of the old sovereign power.

  16. 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. © 2016 Elsevier Inc. All rights reserved.

  17. The study of vacuolar-type ATPases by single particle electron microscopy.

    PubMed

    Zhao, Jianhua; Rubinstein, John L

    2014-12-01

    Nature's molecular machines often work through the concerted action of many different protein subunits, which can give rise to large structures with complex activities. Vacuolar-type ATPases (V-ATPases) are membrane-embedded protein assemblies with a unique rotary catalytic mechanism. The dynamic nature and instability of V-ATPases make structural and functional studies of these enzymes challenging. Electron microscopy (EM) techniques, especially single particle electron cryomicroscopy (cryo-EM) and negative-stain EM, have provided extensive insight into the structure and function of these protein complexes. This minireview outlines what has been learned about V-ATPases using electron microscopy, highlights current challenges for their structural study, and discusses what cryo-EM will allow us to learn about these fascinating enzymes in the future.

  18. Application of the extended discrete element method (XDEM) in the melting of a single particle

    NASA Astrophysics Data System (ADS)

    Baniasadi, Mehdi; Baniasadi, Maryam; Peters, Bernhard

    2017-07-01

    In this contribution, a new method referred to as Extended Discrete Element Method (XDEM) is usedto model melting of a single particle in the fluid media. The XDEM as a Lagrangian-Eulerian framework is the extension of Discrete Element Method (DEM) by considering thermodynamic state such as temperature distribution and is able to link with Computational Fluid Dynamics (CFD) for fluid phase. In order to provide more accurate results, multiscale method was used. The model is validated by comparing predicted results with existing experimental data for melting of a single ice particle in a water bath. In addition, the model has the capability to be extended to the packed bed of particles with different size and properties to produce different liquid phases.

  19. Impact of ultrafast electronic damage in single-particle x-ray imaging experiments

    NASA Astrophysics Data System (ADS)

    Lorenz, U.; Kabachnik, N. M.; Weckert, E.; Vartanyants, I. A.

    2012-11-01

    In single-particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources.

  20. 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.

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

    PubMed Central

    Ludtke, Steven J.

    2016-01-01

    CryoEM single particle reconstruction has been growing rapidly over the last three 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 as well as 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 as well as additional knowledge about particle dynamics. PMID:27572727

  2. Evaluation of Drying Rates of Lignite Particles in Superheated Steam Using Single-Particle Model

    NASA Astrophysics Data System (ADS)

    Kiriyama, Tsuyoshi; Sasaki, Hideaki; Hashimoto, Akira; Kaneko, Shozo; Maeda, Masafumi

    2016-12-01

    Drying rates of lignite particle groups in superheated steam are evaluated using a single-particle model developed for Australian lignite. Size distributions of the particles are assumed to obey the Rosin-Rammler equation with the maximum particle diameters defined as 100, 50, and 6 mm. The results show the drying rate of a lignite group depends strongly on the maximum particle size, and removal of large particles prior to drying is shown to be effective to reduce the drying time. The calculation model is available for simulations of drying behaviors of lignite in various dryers when an appropriate heat transfer coefficient is given. This study simulates the drying of particles smaller than 6 mm using a heat transfer coefficient in a fluidized bed dryer reported elsewhere. The required drying time estimated from the calculation is comparable to the processing time reported in an actual fluidized bed dryer, supporting the validity of the calculation model.

  3. 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

  4. JADAS: a customizable automated data acquisition system and its application to ice-embedded single particles.

    PubMed

    Zhang, Junjie; Nakamura, Natsuko; Shimizu, Yuko; Liang, Nathan; Liu, Xiangan; Jakana, Joanita; Marsh, Michael P; Booth, Christopher R; Shinkawa, Takao; Nakata, Munetaka; Chiu, Wah

    2009-01-01

    The JEOL Automated Data Acquisition System (JADAS) is a software system built for the latest generation of the JEOL Transmission Electron Microscopes. It is designed to partially or fully automate image acquisition for ice-embedded single particles under low dose conditions. Its built-in flexibility permits users to customize the order of various imaging operations. In this paper, we describe how JADAS is used to accurately locate and image suitable specimen areas on a grid of ice-embedded particles. We also demonstrate the utility of JADAS by imaging the epsilon 15 bacteriophage with the JEM3200FSC electron cryo-microscope, showing that sufficient images can be collected in a single 8h session to yield a subnanometer resolution structure which agrees with the previously determined structure.

  5. Operational characteristics of single-particle heat engines and refrigerators with time-asymmetric protocol

    NASA Astrophysics Data System (ADS)

    Pal, P. S.; Saha, Arnab; Jayannavar, A. M.

    2016-09-01

    We have studied the single-particle heat engine and refrigerator driven by time-asymmetric protocol of finite duration. Our system consists of a particle in a harmonic trap with time-periodic strength that drives the particle cyclically between two baths. Each cycle consists of two isothermal steps at different temperatures and two adiabatic steps connecting them. The system works in irreversible mode of operation even in the quasistatic regime. This is indicated by finite entropy production even in the large cycle time limit. Consequently, Carnot efficiency for heat engine or Carnot coefficient of performance (COP) for refrigerators is not achievable. We further analyzed the phase diagram of heat engines and refrigerators. They are sensitive to time-asymmetry of the protocol. Phase diagram shows several interesting features, often counterintuitive. The distribution of stochastic efficiency and COP is broad and exhibits power-law tails.

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

    PubMed Central

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

    2013-01-01

    Surface plasmon assisted catalysis (SPAC) reactions of 4-aminothiophenol (4ATP) to and back from 4,4′-dimercaptoazobenzene (DMAB) have been investigated 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. This SPAC methodology presents a unique platform for studying chemical reactions that are not possible under standard synthetic conditions. PMID:24141289

  7. 3D structure of Syk kinase determined by single particle electron microscopy

    PubMed Central

    Arias-Palomo, Ernesto; Recuero-Checa, María A.; Bustelo, Xosé R.; Llorca, Oscar

    2008-01-01

    The cytoplasmic Syk kinase plays key roles in immune responses and comprises two N-terminal regulatory Src homology 2 (SH2) domains followed by a catalytic region. Atomic structures of these domains have only been solved in isolation. To gain insights into the three-dimensional structure of full-length Syk, we have used single-particle electron microscopy. Syk acquires a closed conformation resembling the inhibited structure of Zap-70, another member of the Syk family. Such configuration suggests an inhibition of the N-terminal domains on its catalytic activity. The phosphotyrosine binding pockets of both SH2 domains are not occluded and they could interact with other phosphoproteins. PMID:18021750

  8. Robust estimation for class averaging in cryo-EM Single Particle Reconstruction.

    PubMed

    Huang, Chenxi; Tagare, Hemant D

    2014-01-01

    Single Particle Reconstruction (SPR) for Cryogenic Electron Microscopy (cryo-EM) aligns and averages the images extracted from micrographs to improve the Signal-to-Noise ratio (SNR). Outliers compromise the fidelity of the averaging. We propose a robust cross-correlation-like w-estimator for combating the effect of outliers on the average images in cryo-EM. The estimator accounts for the natural variation of signal contrast among the images and eliminates the need for a threshold for outlier rejection. We show that the influence function of our estimator is asymptotically bounded. Evaluations of the estimator on simulated and real cryo-EM images show good performance in the presence of outliers.

  9. 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.

  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. Single-particle cryo-electron microscopy of Rift Valley fever virus

    PubMed Central

    Sherman, Michael B.; Freiberg, Alexander N.; Holbrook, Michael R.; Watowich, Stanley J.

    2009-01-01

    Rift Valley fever virus (RVFV; Bunyaviridae; Phlebovirus) is an emerging human veterinary pathogen causing acute hepatitis in ruminants and has the potential to Single-particle cryo-EM reconstruction of RVFV MP-12 hemorrhagic fever in humans. We report a three-dimensional reconstruction of RVFV vaccine strain MP-12 (RVFV MP-12) by cryo-electron microcopy using icosahedral symmetry of individual virions. Although the genomic core of RVFV MP-12 is apparently poorly ordered, the glycoproteins on the virus surface are highly symmetric and arranged on a T=12 icosahedral lattice. Our RVFV MP-12 structure allowed clear identification of inter-capsomer contacts and definition of possible glycoprotein arrangements within capsomers. This structure provides a detailed model for phleboviruses, opens new avenues for high-resolution structural studies of the bunyavirus family, and aids the design of antiviral diagnostics and effective subunit-vaccines. PMID:19304307

  12. Quantitative study of polymer conformation and dynamics by single-particle tracking.

    PubMed Central

    Qian, H; Elson, E L

    1999-01-01

    We present a new method for analyzing the dynamics of conformational fluctuations of individual flexible polymer molecules. In single-particle tracking (SPT), one end of the polymer molecule is tethered to an immobile substratum. A microsphere attached to the other end serves as an optical marker. The conformational fluctuations of the polymer molecule can be measured by optical microscopy via the motion of the microsphere. The bead-and-spring theory for polymer dynamics is further developed to account for the microsphere, and together the measurement and the theory yield quantitative information about molecular conformations and dynamics under nonperturbing conditions. Applying the method to measurements carried out on DNA molecules provides information complementary to recent studies of single DNA molecules under extensional force. Combining high precision measurements with the theoretical analysis presented here creates a powerful tool for studying conformational dynamics of biological and synthetic macromolecules at the single-molecule level. PMID:10049340

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

    DOE PAGES

    Xu, Ping; Kang, Leilei; Mack, Nathan H.; ...

    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

  14. 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.

  15. 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.

  16. Avoiding the pitfalls of single particle cryo-electron microscopy: Einstein from noise

    PubMed Central

    Henderson, Richard

    2013-01-01

    Single particle cryo-electron microscopy is currently poised to produce high-resolution structures of many biological assemblies, but several pitfalls can trap the unwary. This critique highlights one problem that is particularly relevant when smaller structures are being studied. It is known as “Einstein from noise,” in which the experimenter honestly believes they have recorded images of their particles, whereas in reality, most if not all of their data consist of pure noise. Selection of particles using cross-correlation methods can then lead to 3D maps that resemble the model used in the initial selection and provide the illusion of progress. Suggestions are given about how to circumvent the problem. PMID:24106306

  17. 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.

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

    PubMed

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

    2015-06-11

    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. 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.

  20. 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.

  1. 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.

  2. A clustering approach to multireference alignment of single-particle projections in electron microscopy

    PubMed Central

    Sorzano, C.O.S.; Bilbao-Castro, J.R.; Shkolnisky, Y.; Alcorlo, M.; Melero, R.; Caffarena-Fernández, G.; Li, M.; Xu, G.; Marabini, R.; Carazo, J.M.

    2010-01-01

    Two-dimensional analysis of projections of single particles acquired by an electron microscope is a useful tool to help identifying the different kinds of projections present in a dataset and their different projection directions. Such analysis is also useful to distinguish between different kinds of particles or different particle conformations. In this paper we introduce a new algorithm for performing two-dimensional multireference alignment and classification that is based on a Hierarchical clustering approach using correntropy (instead of the more traditional correlation) and a modified criterion for the definition of the clusters specially suited for cases in which the Signal-to-Noise Ratio of the differences between classes is low. We show that our algorithm offers an improved sensitivity over current methods in use for distinguishing between different projection orientations and different particle conformations. This algorithm is publicly available through the software package Xmipp. PMID:20362059

  3. 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.

  4. 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

  5. Dragonfly: an implementation of the expand-maximize-compress algorithm for single-particle imaging.

    PubMed

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

    2016-08-01

    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.

  6. Quantitative link between single-particle dynamics and static structure of supercooled liquids.

    PubMed

    Mittal, Jeetain; Errington, Jeffrey R; Truskett, Thomas M

    2006-09-21

    We present evidence via molecular simulation that the supercooled fluid states of SPC/E water as well as the "repulsive" and "attractive" supercooled fluid states of a recently introduced model for colloids with short-ranged attractions are characterized by the same functional relationship between self-diffusivity and the pair correlation function. We discuss how this simple relationship connects to an earlier finding that the temperature dependency of a supercooled fluid's single-particle dynamics tracks that of its excess entropy (relative to ideal gas). The generality of this observed structure-property relationship is supported by its ability to successfully describe the nontrivial behaviors of these very different types of model systems.

  7. Femtosecond laser fabrication of silver plasmonic structures for application as single particle SERS detectors

    NASA Astrophysics Data System (ADS)

    Huang, H.; Hu, A.; Sivayoganathan, M.; Duley, W. W.; Huang, Z. H.; Zhou, Y.

    2014-04-01

    This work demonstrates the feasibility of fabricating silver nanoparticles (NPs) into sub-micron and micron-sized core-satellite structures by exposure to femtosecond laser radiation. We find that the size and shape of these structures can be tailored by adjusting laser fluence (1.8-10.5 J cm-2) and irradiation time (20-60 min), along with the concentration of NPs in aqueous solution (0.01-0.05 mM). Raman measurements of adenine molecules adsorbed on these sub-micron substrates indicate that core-satellite structures having complex shapes are effective as sensitive surface enhanced Raman spectroscopy (SERS) substrates. The sensitivity is such that these structures are potentially useful as single particle SERS substrates for bio-sensing. Finite difference time domain (FDTD) simulation results indicate that these structures can be generated by the joining of NPs in response to localized surface plasmon induced hotspots.

  8. 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

  9. 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.

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

    PubMed

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

    2015-02-01

    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. Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions

    SciTech Connect

    Szilner, S.; Jelavic-Malenica, D.; Soic, N.; Corradi, L.; Fioretto, E.; Sahin, E.; Silvestri, R.; Stefanini, A. M.; Valiente-Dobon, J. J.; Haas, F.; Lebhertz, D.; Bouhelal, M.; Caurier, E.; Courtin, S.; Goasduff, A.; Nowacki, F.; Ur, C. A.; Beghini, S.; Farnea, E.

    2011-07-15

    New {gamma} transitions have been identified in argon isotopes in {sup 40}Ar + {sup 208}Pb multiple transfer reactions by exploiting, in a fragment-{gamma} measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large {gamma} arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states.

  12. Single-particle and collective motion in nuclear open quantum systems

    NASA Astrophysics Data System (ADS)

    Fossez, Kevin

    2017-01-01

    The properties of drip-line nuclei are profoundly affected by the environment of continuum states and the presence of decay channels. Their description requires the development of realistic theoretical approaches rooted in the open quantum system framework. However this formidable task presents many challenges and calls for closer collaborations between theorists and experimentalists. In this presentation a brief introduction to the problem of the description of weakly bound and unbound nuclei will be given with an emphasis on the relationship between nuclear structure and reactions. This will be illustrated by two recent investigations on the nuclei 11Be and 39Mg, where the role of the interplay between the collectivity and the continuum on single-particle structure has been studied. Finally the question of the existence of a nuclear system in the continuum is discussed for the case of the four-neutron system.

  13. Single-particle tracking for studying nanomaterial dynamics: applications and fundamentals in drug delivery.

    PubMed

    Zagato, Elisa; Forier, Katrien; Martens, Thomas; Neyts, Kristiaan; Demeester, Jo; De Smedt, Stefaan; Remaut, Katrien; Braeckmans, Kevin

    2014-05-01

    Many macromolecular therapeutics could potentially treat genetic disorders and cancer. They have, however, not yet reached the clinical stage owing to a lack of suitable carriers that can bring the therapeutics from the administration site to the subcellular site in target cells. One of the reasons that is hindering the development of such carriers is the limited knowledge of their transport dynamics and intracellular processing. Single-particle tracking (SPT) microscopy, thanks to its single molecule sensitivity and its broad applicability, has found its entry in the field of drug delivery to get an answer to these questions. This review aims to introduce the fundamentals of SPT to the drug delivery community and highlight the most recent discoveries obtained with SPT in the field of drug delivery.

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

    PubMed Central

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

    2015-01-01

    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

  15. A single particle model to simulate the dynamics of entangled polymer melts

    NASA Astrophysics Data System (ADS)

    Kindt, P.; Briels, W. J.

    2007-10-01

    We present a computer simulation model of polymer melts representing each chain as one single particle. Besides the position coordinate of each particle, we introduce a parameter nij for each pair of particles i and j within a specified distance from each other. These numbers, called entanglement numbers, describe the deviation of the system of ignored coordinates from its equilibrium state for the given configuration of the centers of mass of the polymers. The deviations of the entanglement numbers from their equilibrium values give rise to transient forces, which, together with the conservative forces derived from the potential of mean force, govern the displacements of the particles. We have applied our model to a melt of C800H1602 chains at 450K and have found good agreement with experiments and more detailed simulations. Properties addressed in this paper are radial distribution functions, dynamic structure factors, and linear as well as nonlinear rheological properties.

  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; 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.

  17. 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

    2016-06-13

    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.

  18. 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.

  19. Structure of archaeal proteasomal ATPase PAN by single particle cryoEM

    NASA Astrophysics Data System (ADS)

    Royal, Renee; Yadong, Yu; Cheng, Yifan

    2010-02-01

    ATP dependent protein degradation in eukaryotes by 26S proteasome are essential for many cellular processes including apoptosis, cell cycles and signal transduction. 26S proteasome is composed of a barrel shaped 20S protease core and two regulatory particles capped on each end. The ATPases in the 19S regulatory particles unfold and translocate substrates into 20S for degradation. Archaea has a homologous yet simpler 20S proteasome and a regulatory ATPase, proteasome activating nucleotidase (PAN.) In this study we used single particle cryoEM to study the three dimensional structure of PAN. We obtained a 3D reconstruction of PAN at a resolution of 18 Angstroms. By docking the atomic structure of PAN's N-terminal domain and ATPase domain to the atomic structure determined x-ray crystallography, we generated an atomic model of full length PAN ATPase. )

  20. Optimization of probe-laser focal offsets for single-particle tracking.

    PubMed

    Chang, Ai-Tang; Chang, Yi-Ren; Chi, Sien; Hsu, Long

    2012-08-10

    In optical tweezers applications, tracking a trapped particle is essential for force measurement. One of the most popular techniques for single-particle tracking is achieved by analyzing the forward and backward light pattern, scattered by the target particle trapped by a trap laser beam, of an additional probe-laser beam with different wavelength whose focus is slightly apart from the trapping center. However, the optimized focal offset has never been discussed. In this paper, we investigate the tracking range and sensitivity as a function of the focal offset between the trapping and the probe-laser beams. As a result, the optimized focal offsets are a 3.3-fold radius ahead and a 2.0-fold radius behind the trapping laser focus in the forward tracking and the backward tracking, respectively. The experimental result agrees well with a theoretical prediction using the Mie scattering theory.

  1. [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".

  2. 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).

  3. 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

  4. Aging and removal of Black Carbon measured using a Single Particle Soot Photometer in East Asia

    NASA Astrophysics Data System (ADS)

    Kanaya, Y.; Miyakawa, T.; Taketani, F.; Oshima, N.; PAN, X.; Komazaki, Y.; Kondo, Y.; Takami, A.; Yoshino, A.

    2015-12-01

    Black carbon (BC) aerosol is one of the most important aerosols, affecting the Earth's radiative budget both directly through light absorption and indirectly by acting as cloud condensation and ice nuclei. Microphysical parameters of soot aerosols are important to assess their roles in atmosphere. A single particle soot photometer (SP2, Droplet Measurement Technologies Inc.) can be used to detect and quantify the mass of refractory BC (rBC) in a soot-containing particle. We conducted ground-measurements of rBC-containing particles using the SP2 at Yokosuka (near industrial sources, early summer of 2014, Fig1) and at Fukue island (outflow from Asian continent, spring of 2015, Fig1). During Fukue observation, we measured carbon monoxide (CO) mixing ratio (by 48C, Themo Scientific, Inc.) which is useful for investigating polluted air masses. Air mass histories were analyzed with backward trajectories from the sampling point and precipitation along the trajectory calculated using the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory model with the meteorological data sets from NCEP's GDAS. We analysed number-/mass-size distributions and mixing states of rBC-containing particles considering the differences in air mass characteristics and history. The observed rBC mass concentrations (at STP) were ranging from ~50 ng m-3 at Fukue island to ~2000 ng m-3 near industrial sources. The size distributions of rBC-containing particles were systematically changed depending on the sites and air mass histories. Modal mass-equivalent diameters of the observed mass-size distributions showed minima (~0.16 μm) near source area and maxima (~0.21 μm) at Fukue island for Asian outflow period without wet removal. In the presentation, we synthetically discuss the relationship between rBC microphysics and air mass characteristics and histories.

  5. Single-particle dynamics near the glass transition of a metallic glass.

    PubMed

    Lü, Y J; Wang, W H

    2016-12-01

    The single-particle dynamics of the glass-forming Cu_{50}Zr_{50} alloy, from the supercooled liquid well above the glass-transition temperature, T_{g} to the glassy state, is studied by using the molecular dynamics simulations. When the liquid is cooled below 1.2T_{g}, the dynamics heterogeneity characterized by the cage-jump motion becomes increasingly pronounced. The analyses based on the continuous time random walk method indicate that the liquid falls out of equilibrium in the present simulation time scale when it is cooled into the regime below 1.02T_{g}. However, we find that the jump length and the jump rate do not display the non-equilibrium behaviors even in the glassy state below T_{g}, which allows us to study the intrinsic dynamic characteristics through T_{g}. The mean waiting time between two successive jumps has a rapid growth following the Vogel-Fulcher-Tammann law as the non-equilibrium regime is approached, in analogy with the temperature behaviors of transport properties for fragile supercooled liquids. In contrast, the jump rate maintains the Arrhenius decay and the jump length has even a weaker temperature dependence when the liquid is cooled into glassy state. We find that a pronounced enhancement of the spatial correlation of jumps occurs accompanied by the glass transition: the string-like cooperative jumps dominate the fast motion instead of the uncorrelated and individual jumps. Our work offers an insight into the equilibrium effect of the single-particle dynamics in glass transition.

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

    NASA Astrophysics Data System (ADS)

    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), 10.1073/pnas.1321682111], 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 ∝Ren -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 . 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.

  7. 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

  8. 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.

  9. 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

  10. Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

    PubMed

    Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T

    2013-03-01

    Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Single-particle dynamics near the glass transition of a metallic glass

    NASA Astrophysics Data System (ADS)

    Lü, Y. J.; Wang, W. H.

    2016-12-01

    The single-particle dynamics of the glass-forming C u50Z r50 alloy, from the supercooled liquid well above the glass-transition temperature, Tg to the glassy state, is studied by using the molecular dynamics simulations. When the liquid is cooled below 1.2 Tg , the dynamics heterogeneity characterized by the cage-jump motion becomes increasingly pronounced. The analyses based on the continuous time random walk method indicate that the liquid falls out of equilibrium in the present simulation time scale when it is cooled into the regime below 1.02 Tg . However, we find that the jump length and the jump rate do not display the non-equilibrium behaviors even in the glassy state below Tg, which allows us to study the intrinsic dynamic characteristics through Tg. The mean waiting time between two successive jumps has a rapid growth following the Vogel-Fulcher-Tammann law as the non-equilibrium regime is approached, in analogy with the temperature behaviors of transport properties for fragile supercooled liquids. In contrast, the jump rate maintains the Arrhenius decay and the jump length has even a weaker temperature dependence when the liquid is cooled into glassy state. We find that a pronounced enhancement of the spatial correlation of jumps occurs accompanied by the glass transition: the string-like cooperative jumps dominate the fast motion instead of the uncorrelated and individual jumps. Our work offers an insight into the equilibrium effect of the single-particle dynamics in glass transition.

  16. 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

  17. Neutrino Oscillations in Dense Matter

    NASA Astrophysics Data System (ADS)

    Lobanov, A. E.

    2017-03-01

    A modification of the electroweak theory, where the fermions with the same electroweak quantum numbers are combined in multiplets and are treated as different quantum states of a single particle, is proposed. In this model, mixing and oscillations of particles arise as a direct consequence of the general principles of quantum field theory. The developed approach enables one to calculate the probabilities of the processes taking place in the detector at long distances from the particle source. Calculations of higher-order processes, including computation of the contributions due to radiative corrections, can be performed in the framework of the perturbation theory using the regular diagram technique. As a result, the analog to the Dirac-Schwinger equation of quantum electrodynamics describing neutrino oscillations and its spin rotation in dense matter can be obtained.

  18. Assignment of single particle configurations in odd-A nuclei near A~100 with angular correlation measurements

    NASA Astrophysics Data System (ADS)

    Ramayya, A. V.; Hamilton, J. H.; Hwang, J. K.; Liu, S. H.; Daniel, A. V.; Goodin, C.; Luo, Y. X.; Rasmussen, J. O.; Stone, N. J.; Zhu, S. J.; Li, K.

    2011-01-01

    The multipole mixing ratios of ΔI = 1 transitions between levels in rotational bands built on single-particle states in odd neutron nuclei are dependent on the configurations of the states. In particular, the mixing ratio can be used to distinguish between several possible single-particle configurations if interpreted with the particle plus axial-rotor model (PRM). This work features the first determination of the ground-state configurations of 109,111Ru. The single-particle structures of the ground states of 101Zr and 103,105,107Mo as well as excited states in 103,107Mo are also investigated, with a new result found in 107Mo.

  19. 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.

  20. Single Particle Source Profiles of Gasoline and Diesel Powered Vehicles, Biomass Burning and Coal Combustion Exhaust Emissions

    NASA Astrophysics Data System (ADS)

    Suess, D. T.; Prather, K. A.; Schauer, J.; Cass, G. R.

    2001-12-01

    Vehicular exhaust, biomass burning, and coal combustion are three significant aerosol sources that have local to global impacts on the earth's atmosphere. They may also contribute to health effects as they can emit carcinogenic species such as polycyclic aromatic hydrocarbons (PAH) and trace metals including beryllium and vanadium. In these source characterization studies, combustion products were diluted to near ambient temperature and pressure using a two stage dilution source sampler. Diluted exhaust emissions were analyzed with an aerosol time-of-flight mass spectrometer (ATOFMS) obtaining real-time measurements of single particle size and chemical composition. In addition, samples were collected using a micro-orifice uniform deposit impactor (MOUDI), which was operated in a manner compatible with advanced chemical analysis techniques, for size segregated mass concentrations. Due to the importance of these particle sources to the atmosphere, differentiating these emissions from each other and other particle sources is essential. Since ATOFMS is a relatively new single particle analysis technique, source characterization experiments are needed to determine qualitative signatures of specific particulate sources for their ambient identification. ATOFMS single particle mass spectra will be discussed introducing chemically distinct single particle types emitted from these combustion sources. Numerous particle types are emitted from each source, as indicated by distinct chemical associations on the single particle level. Examples include, the chemical associations of vanadium with organic carbon (OC) in gasoline powered vehicle emissions, calcium with black carbon (BC) in diesel powered vehicle emissions, beryllium and boron with BC in coal combustion emissions, and potassium with OC from biomass burning emissions. Most importantly, the overall particle type distributions from each source differ significantly. Finally, complementary MOUDI mass distribution data will

  1. Technical Note: The single particle soot photometer fails to reliably detect PALAS soot nanoparticles

    NASA Astrophysics Data System (ADS)

    Gysel, M.; Laborde, M.; Mensah, A. A.; Corbin, J. C.; Keller, A.; Kim, J.; Petzold, A.; Sierau, B.

    2012-12-01

    The single particle soot photometer (SP2) uses laser-induced incandescence (LII) for the measurement of atmospheric black carbon (BC) particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit. It is commonly accepted that a particle must contain at least several tenths of a femtogram BC in order to be detected by the SP2. Here we show the result that most BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM), is clearly above the typical lower detection limit of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST), fullerene soot and carbon black particles (Cabot Regal 400R) reveals that particle morphology can affect the SP2's lower detection limit. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, most PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to their vaporisation temperature because of their small size (Dpp ≈ 5-10 nm). Previous knowledge from pulsed laser-induced incandescence indicated that particle morphology might have an effect on the SP2's lower detection limit, however, an increase of the lower detection limit by a factor of ∼5-10, as reported here for PALAS soot, was not expected. In conclusion, the SP2's lower detection limit at a certain laser power depends primarily on the total BC mass per particle for compact particles with sufficiently high effective density. By contrast, the BC mass per primary particle

  2. Technical Note: The single particle soot photometer fails to detect PALAS soot nanoparticles

    NASA Astrophysics Data System (ADS)

    Gysel, M.; Laborde, M.; Corbin, J. C.; Mensah, A. A.; Keller, A.; Kim, J.; Petzold, A.; Sierau, B.

    2012-07-01

    The single particle soot photometer (SP2) uses laser-induced incandescence (LII) for the measurement of atmospheric black carbon (BC) particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit (LDL). It is commonly accepted that a particle must contain at least several tenths of femtograms BC in order to be detected by the SP2. Here we show the unexpected result that BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM), is clearly above the typical LDL of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST), fullerene soot and carbon black particles (Cabot Regal 400R) reveals that particle morphology can affect the SP2's LDL. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely-packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, the PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to vaporisation because of their small size (primary particle diameter ~5-10 nm). It is not surprising that particle morphology can have an effect on the SP2's LDL, however, such a dramatic effect as reported here for PALAS soot was not expected. In conclusion, the SP2's LDL at a certain laser power depends on total BC mass per particle for compact particles with sufficiently high effective density. However, for fractal-like agglomerates of very small primary particles and low fractal dimension, the BC mass per primary particle determines the limit of detection, independent of the total particle mass

  3. 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

  4. Characterization of individual fine and ultrafine particles with a real-time single particle mass spectrometer

    NASA Astrophysics Data System (ADS)

    Reinard, Melissa S.

    2008-10-01

    Designed to analyze aerosols in ambient settings, the Real-Time Single Particle Mass Spectrometer (RSMS) provides a highly time-resolved measurement of the physical and chemical properties of individual fine (<2.5 mum dia.) and ultrafine (<0.1 mum dia.) particles. Understanding aerosols within this size range is crucial as these particles greatly impact both human health and the environment. Data collected by RSMS can be used identify particle sources and atmospheric processes. RSMS was deployed to Wilmington, DE during 2005-2006 as part of E-DATAS (Enhanced Delaware Air Toxics Assessment Study), a collaboration with the Delaware Department of Natural Resources (DNREC), the Environmental Protection Agency (EPA) and Duke University. Mass spectra acquired by RSMS were compared to a Scanning Mobility Particle Sizer (SMPS) to give a quantitative estimate of the chemical composition of PM1.0 (particulate matter <1.0 mum dia.) impacting the city. A method to collect and analyze particles directly from emission stacks of industrial facilities was developed to help identify sources of PM. Single particle mass spectrometry, in general, has remained primarily a qualitative technique due to several instrumental limitations which affect the data. First, the shot-to-shot variation in the laser pulse caused inconsistencies between the mass spectra of particles with the same composition. To determine whether this variation was systematic or random, the covariance between ions was calculated for laboratory generated aerosols. Second, RSMS was found to be highly sensitive to specific chemical species such as ammonium nitrate and transition/alkali metals. When these compounds are present in a particle they dominate the mass spectra and dwarf other the signal from other components to the baseline. To explore this bias, data collected by RSMS in Wilmington, DE was compared to data also collected in Wilmington by the quantitative NanoAerosol Mass Spectrometer (NAMS). Finally, a light

  5. Single Particle Analysis by Combined Chemical Imaging to Study Episodic Air Pollution Events in Vienna

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Eitenberger, Elisabeth; Friedbacher, Gernot; Brenner, Florian; Hutter, Herbert; Schauer, Gerhard; Kistler, Magdalena; Greilinger, Marion; Lohninger, Hans; Lendl, Bernhard; Kasper-Giebl, Anne

    2017-04-01

    The aerosol composition of a city like Vienna is characterized by a complex interaction of local emissions and atmospheric input on a regional and continental scale. The identification of major aerosol constituents for basic source appointment and air quality issues needs a high analytical effort. Exceptional episodic air pollution events strongly change the typical aerosol composition of a city like Vienna on a time-scale of few hours to several days. Analyzing the chemistry of particulate matter from these events is often hampered by the sampling time and related sample amount necessary to apply the full range of bulk analytical methods needed for chemical characterization. Additionally, morphological and single particle features are hardly accessible. Chemical Imaging evolved to a powerful tool for image-based chemical analysis of complex samples. As a complementary technique to bulk analytical methods, chemical imaging can address a new access to study air pollution events by obtaining major aerosol constituents with single particle features at high temporal resolutions and small sample volumes. The analysis of the chemical imaging datasets is assisted by multivariate statistics with the benefit of image-based chemical structure determination for direct aerosol source appointment. A novel approach in chemical imaging is combined chemical imaging or so-called multisensor hyperspectral imaging, involving elemental imaging (electron microscopy-based energy dispersive X-ray imaging), vibrational imaging (Raman micro-spectroscopy) and mass spectrometric imaging (Time-of-Flight Secondary Ion Mass Spectrometry) with subsequent combined multivariate analytics. Combined chemical imaging of precipitated aerosol particles will be demonstrated by the following examples of air pollution events in Vienna: Exceptional episodic events like the transformation of Saharan dust by the impact of the city of Vienna will be discussed and compared to samples obtained at a high alpine

  6. Classification of the PALMS single particle mass spectral data from Atlanta by regression tree analysis

    NASA Astrophysics Data System (ADS)

    Middlebrook, A. M.; Murphy, D. M.; Lee, S.; Lee, S.; Lee, S.; Thomson, D. S.; Thomson, D. S.

    2001-12-01

    During the Atlanta Supersites project in August 1999, the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument collected over 500,000 individual particle spectra. The Atlanta data were originally analyzed by examining combinations of peaks and relative peak areas [Lee et al., 2001a,b], and a wide range of particle components such as sulfate, nitrate, mineral species, metals, organic species, and elemental carbon were detected. To further study the dataset, a classification program using regression tree analysis was developed and applied. Spectral data were compressed into a lower resolution spectrum (every 0.25 mass units) of the raw data and a list of peak areas (every mass unit). Each spectrum started as a normalized classification vector by itself. If the dot product of two classification vectors was within a certain threshold, they were combined into a new classification. The new classification vector was a normalized running average of the classifications being combined. In subsequent steps, the threshold for combining classifications was continuously lowered until a reasonable number of classifications remained. After the final iteration, each spectrum was compared individually with the entire set of classification vectors. Classifications were also combined manually. The classification results from the Atlanta data are generally consistent with those determined by peak identification. However, the classification program identified specific patterns in the mass spectra that were not found by peak identification and generated new particle types. Furthermore, rare particle types that may affect human health were studied in more detail. A description of the classification program as well as the results for the Atlanta data will be presented. Lee, S.-H., D. M. Murphy, D. S. Thomson, and A. M. Middlebrook, Chemical components of single particles measured with particle analysis by laser mass spectrometry (PALMS) during the Atlanta Supersites Project

  7. Analysis of the characteristics of single atmospheric particles in Chengdu using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Junke; Luo, Bin; Zhang, Jianqiang; Ouyang, Feng; Song, Hongyi; Liu, Peichuan; Cao, Pan; Schäfer, Klaus; Wang, Shigong; Huang, Xiaojuan; Lin, Yongfu

    2017-05-01

    Chengdu, the capital of Sichuan Province and the main city in Sichuan basin, is one of the heavily polluted cities in China. The characteristics of single particles in the atmosphere over Chengdu are critical for the in-depth understanding of their sources, formation mechanisms, and effects. In this study, a continuous ambient aerosol measurement was performed in summer in Chengdu with a single particle aerosol mass spectrometer (SPAMS) and other monitoring instruments. The particulate matter (PM) mass concentrations were low during our study period: PM2.5 and PM10 (aerosol particles with an aerodynamic diameter of less than 2.5 or 10 μm) were 40.5 ± 23.6 μg m-3 and 67.0 ± 38.1 μg m-3, respectively. This was mainly caused by the favorable meteorological conditions during the summer season. Twelve particle types were identified and classified as dust particles (Dust), four types of carbonaceous particles, organic nitrogen and potassium containing particles (KCN), four types of secondary particles, Na-K-containing particles (NaK), and metal-containing particles (Metal). The highest contribution of particles was from potassium with elemental carbon (KEC; 23.0%), and the lowest from elemental carbon (EC; 0.2%). All types of particles showed different diurnal variations and size distributions, which were closely related to their sources and reactions in the atmosphere. The eastern and southern air masses corresponded with high PM2.5 mass concentrations. The contributions of KEC and K-sulfate (KSO4) particles to PM2.5 were clearly higher than those in air masses from the southeast. During polluted days, the contributions of KEC and KSO4 particles increased, while the contributions of organic carbon (OC), combined OC and EC particles (OCEC), and K-nitrate (KNO3) particles decreased. This shows the importance of biomass burning and industrial emissions for the PM2.5 pollution in Chengdu. These results will be useful for the in-depth understanding of the PM2

  8. 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,…

  9. 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…

  10. The Archaeology of Heroes: Carlyle, Foucault and the Pedagogy of Interdisciplinary Narrative Discourse

    ERIC Educational Resources Information Center

    Campbell, Louise

    2017-01-01

    This paper argues in favour of the beneficial currency of Thomas Carlyle's "On Heroes, Hero-worship and the Heroic in History" in three ways, each of which finds the basis of its critique in aspects of Foucault's theories of discursive practice, as explored in Foucault's theories of historical discourse; 1) that Carlyle's terminology…

  11. 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…

  12. Discourse, Complexity, Normativity: Tracing the Elaboration of Foucault's Materialist Concept of Discourse

    ERIC Educational Resources Information Center

    Olssen, Mark

    2014-01-01

    In this article, I want to suggest that it is through the elaboration of the concept of discourse that the differences between Foucault and thinkers like Habermas, Hegel and Marx can best be understood. Foucault progressively develops a conception of discourse as a purely historical category that resists all reference to transcendental principles…

  13. 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…

  14. 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,…

  15. Discourse, Complexity, Normativity: Tracing the Elaboration of Foucault's Materialist Concept of Discourse

    ERIC Educational Resources Information Center

    Olssen, Mark

    2014-01-01

    In this article, I want to suggest that it is through the elaboration of the concept of discourse that the differences between Foucault and thinkers like Habermas, Hegel and Marx can best be understood. Foucault progressively develops a conception of discourse as a purely historical category that resists all reference to transcendental principles…

  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. The Rhetoric of Revelation: The Case of Biographical Representations of Michel Foucault.

    ERIC Educational Resources Information Center

    Nash, Susan Smith

    Scholars and educators concerned with the work of Michel Foucault should approach James Miller's biography "The Passion of Michel Foucault" with a fair degree of skepticism because the author's motives for writing the book call into question his findings. According to Miller's own preface, he enters his project with his agenda already…

  18. 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…

  19. 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…

  20. 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,…

  1. 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…

  2. 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…

  3. 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…

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

    PubMed

    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.

  5. 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.

  6. 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.

  7. 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.

  8. Quantum Interference as a Process of Accumulation of Single-Particle Arrivals

    SciTech Connect

    Bozic, Mirjana; Arsenovic, Dusan

    2005-10-17

    Single-particle interference experiments brought new arguments supporting objective reality of matter and photon waves, compatibility of particle and wave properties of quantons, the evidence of existence of particles trajectories during the accumulation of an interference pattern, and the necessity of completing quantum mechanics by the description of single events. By integrating the probability density of transverse momenta multiplied by the probability density of particle distribution at the slits over all transverse momenta and over all slit points, we have derived the expression for the probability density for the particle's arrival at time t to a point behind a grating. The agreement with usual probability density given by the modulus square of the wave function in coordinate representation is very good in the far field. In the near field the agreement is poor. This was demonstrated previously for gratings with a small number of slits, and is demonstrated in our paper for a many-slits grating, where the Talbot Laue effect exists. Further study of the form of particles' trajectories in the near field is necessary. In addition to obtaining agreement with the distribution after many events have been accumulated in the far field, with this approach one might also obtain a distribution of a smaller number of events. For that we do not integrate over all momenta and slit points at the grating, but over randomly chosen ones.

  9. Collective and single-particle excitations in two-dimensional dipolar Bose gases

    NASA Astrophysics Data System (ADS)

    Filinov, A.; Bonitz, M.

    2012-10-01

    The Berezinskii-Kosterlitz-Thouless transition in two-dimensional dipolar systems has been studied recently by path integral Monte Carlo simulations [A. Filinov , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.105.070401 105, 070401 (2010)]. Here, we complement this analysis and study temperature-coupling strength dependence of the density (particle-hole) and single-particle (SP) excitation spectra both in superfluid and normal phases. The dynamic structure factor, S(q,ω), of the longitudinal excitations is rigorously reconstructed with full information on damping. The SP spectral function, A(q,ω), is worked out from the one-particle Matsubara Green's function. A stochastic optimization method is applied for reconstruction from imaginary times. In the superfluid regime sharp energy resonances are observed in both the density and SP excitations. The involved hybridization of both spectra is discussed. In contrast, in the normal phase, when there is no coupling, the density modes, beyond acoustic phonons, are significantly damped. Our results generalize previous zero-temperature analyses based on variational many-body wave functions [F. Mazzanti , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.110405 102, 110405 (2009); D. Hufnagl , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.065303 107, 065303 (2011)], where the underlying physics of the excitation spectrum and the role of the condensate has not been addressed.

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

    PubMed

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

    2015-12-10

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Single-particle thermal diffusion of charged colloids: double-layer theory in a temperature gradient.

    PubMed

    Dhont, J K G; Briels, W J

    2008-01-01

    The double-layer contribution to the single-particle thermal diffusion coefficient of charged, spherical colloids with arbitrary double-layer thickness is calculated and compared to experiments. The calculation is based on an extension of the Debye-Hückel theory for the double-layer structure that includes a small temperature gradient. There are three forces that constitute the total thermophoretic force on a charged colloidal sphere due to the presence of its double layer: i) the force F W that results from the temperature dependence of the internal electrostatic energy W of the double layer, ii) the electric force Fel with which the temperature-induced non-spherically symmetric double-layer potential acts on the surface charges of the colloidal sphere and iii) the solvent-friction force Fsol on the surface of the colloidal sphere due to the solvent flow that is induced in the double layer because of its asymmetry. The force F W will be shown to reproduce predictions based on irreversible-thermodynamics considerations. The other two forces Fel and Fsol depend on the details of the temperature-gradient-induced asymmetry of the double-layer structure which cannot be included in an irreversible-thermodynamics treatment. Explicit expressions for the thermal diffusion coefficient are derived for arbitrary double-layer thickness, which complement the irreversible-thermodynamics result through the inclusion of the thermophoretic velocity resulting from the electric- and solvent-friction force.

  16. Single particle dynamics of water confined in a hydrophobically modified MCM-41-S nanoporous matrix

    NASA Astrophysics Data System (ADS)

    Faraone, Antonio; Liu, Kao-Hsiang; Mou, Chung-Yuan; Zhang, Yang; Chen, Sow-Hsin

    2009-04-01

    The single particle dynamics of water confined in a hydrophobically modified MCM-41-S sample has been studied using three high resolution quasielastic neutron scattering spectrometers in the temperature range from 300 to 210 K. A careful modeling of the dynamics allowed us to obtain good agreement among the results obtained with the three instruments, which have very different energy resolutions. The picture arising from the data is that, because of the heterogenous environment experienced by the water molecules, the dynamics show a broad distribution of relaxation times. However, the Fickian diffusive behavior is retained. In the investigated temperature range we found no evidence of the dynamic crossover, from a non-Arrhenius to an Arrhenius behavior, which was detected for water confined in hydrophilic MCM-41-S. This finding is in agreement with what was reported by Chu et al. [Phys. Rev. E 76, 021505 (2007)] for water confined in other hydrophobic confining media that the dynamic crossover takes place at a much lower temperature. The results reported in the paper help clarify the role that the chemical interaction between the water molecules and the walls of the confining host plays in determining the characteristics of the water dynamics, as compared to purely geometric constraints such as the size and shape of the pores.

  17. FATES: a flexible analysis toolkit for the exploration of single-particle mass spectrometer data

    NASA Astrophysics Data System (ADS)

    Sultana, Camille M.; Cornwell, Gavin C.; Rodriguez, Paul; Prather, Kimberly A.

    2017-04-01

    Single-particle mass spectrometer (SPMS) analysis of aerosols has become increasingly popular since its invention in the 1990s. Today many iterations of commercial and lab-built SPMSs are in use worldwide. However, supporting analysis toolkits for these powerful instruments are outdated, have limited functionality, or are versions that are not available to the scientific community at large. In an effort to advance this field and allow better communication and collaboration between scientists, we have developed FATES (Flexible Analysis Toolkit for the Exploration of SPMS data), a MATLAB toolkit easily extensible to an array of SPMS designs and data formats. FATES was developed to minimize the computational demands of working with large data sets while still allowing easy maintenance, modification, and utilization by novice programmers. FATES permits scientists to explore, without constraint, complex SPMS data with simple scripts in a language popular for scientific numerical analysis. In addition FATES contains an array of data visualization graphic user interfaces (GUIs) which can aid both novice and expert users in calibration of raw data; exploration of the dependence of mass spectral characteristics on size, time, and peak intensity; and investigations of clustered data sets.

  18. The effect of model fidelity on prediction of char burnout for single-particle coal combustion

    SciTech Connect

    McConnell, Josh; Sutherland, James C.

    2016-07-09

    In this study, practical simulation of industrial-scale coal combustion relies on the ability to accurately capture the dynamics of coal subprocesses while also ensuring the computational cost remains reasonable. The majority of the residence time occurs post-devolatilization, so it is of great importance that a balance between the computational efficiency and accuracy of char combustion models is carefully considered. In this work, we consider the importance of model fidelity during char combustion by comparing combinations of simple and complex gas and particle-phase chemistry models. Detailed kinetics based on the GRI 3.0 mechanism and infinitely-fast chemistry are considered in the gas-phase. The Char Conversion Kinetics model and nth-Order Langmuir–Hinshelwood model are considered for char consumption. For devolatilization, the Chemical Percolation and Devolatilization and Kobayashi-Sarofim models are employed. The relative importance of gasification versus oxidation reactions in air and oxyfuel environments is also examined for various coal types. Results are compared to previously published experimental data collected under laminar, single-particle conditions. Calculated particle temperature histories are strongly dependent on the choice of gas phase and char chemistry models, but only weakly dependent on the chosen devolatilization model. Particle mass calculations were found to be very sensitive to the choice of devolatilization model, but only somewhat sensitive to the choice of gas chemistry and char chemistry models. High-fidelity models for devolatilization generally resulted in particle temperature and mass calculations that were closer to experimentally observed values.

  19. 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)

  20. A toolbox for ab initio 3-D reconstructions in single-particle electron microscopy.

    PubMed

    Voss, Neil R; Lyumkis, Dmitry; Cheng, Anchi; Lau, Pick-Wei; Mulder, Anke; Lander, Gabriel C; Brignole, Edward J; Fellmann, Denis; Irving, Christopher; Jacovetty, Erica L; Leung, Albert; Pulokas, James; Quispe, Joel D; Winkler, Hanspeter; Yoshioka, Craig; Carragher, Bridget; Potter, Clinton S

    2010-03-01

    Structure determination of a novel macromolecular complex via single-particle electron microscopy depends upon overcoming the challenge of establishing a reliable 3-D reconstruction using only 2-D images. There are a variety of strategies that deal with this issue, but not all of them are readily accessible and straightforward to use. We have developed a "toolbox" of ab initio reconstruction techniques that provide several options for calculating 3-D volumes in an easily managed and tightly controlled work-flow that adheres to standard conventions and formats. This toolbox is designed to streamline the reconstruction process by removing the necessity for bookkeeping, while facilitating transparent data transfer between different software packages. It currently includes procedures for calculating ab initio reconstructions via random or orthogonal tilt geometry, tomograms, and common lines, all of which have been tested using the 50S ribosomal subunit. Our goal is that the accessibility of multiple independent reconstruction algorithms via this toolbox will improve the ease with which models can be generated, and provide a means of evaluating the confidence and reliability of the final reconstructed map.

  1. 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.

  2. 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.

  3. High Precision Density Measurements of Single Particles: The Density of Metastable Phases

    SciTech Connect

    Zelenyuk, Alla; Cai, Yong; Chieffo, Logan; Imre, Dan G.

    2005-10-01

    We describe a system designed to measure the size, composition and density of individual particles in real-time. It uses a DMA to select a monodisperse particle population and the single particle mass spectrometer to measure individual particle mass spectrometer to measure individual particle aerodynamic diameter and composition. Mobility and aerodynamic diameters are used to extract particle density. The addition of individual particle density to the mass spectrum is intended to improve the data classification process. In the present paper we demonstrate that the system has the requisite accuracy and resolution to make this approach practicable. We also present a high precision variant that uses an internal calibrant to remove any of the systematic errors and significantly improves the measurement quality. The high precision scheme is most suitable for laboratory studies making it possible to follow slight changes in particle density. An application of the system to measure the density of hygroscopic particles of atmospheric importance in metastable phases near zero relative humidity is presented. The density data are consistent with conclusions reached in a number of other studies that some particle systems of atmospheric significance once deliquesced persist as droplets down to near zero relative humidity.

  4. Imaging whole Escherichia coli bacteria by using single-particle x-ray diffraction.

    PubMed

    Miao, Jianwei; Hodgson, Keith O; Ishikawa, Tetsuya; Larabell, Carolyn A; LeGros, Mark A; Nishino, Yoshinori

    2003-01-07

    We report the first experimental recording, to our knowledge, of the diffraction pattern from intact Escherichia coli bacteria using coherent x-rays with a wavelength of 2 A. By using the oversampling phasing method, a real space image at a resolution of 30 nm was directly reconstructed from the diffraction pattern. An R factor used for characterizing the quality of the reconstruction was in the range of 5%, which demonstrated the reliability of the reconstruction process. The distribution of proteins inside the bacteria labeled with manganese oxide has been identified and this distribution confirmed by fluorescence microscopy images. Compared with lens-based microscopy, this diffraction-based imaging approach can examine thicker samples, such as whole cultured cells, in three dimensions with resolution limited only by radiation damage. Looking forward, the successful recording and reconstruction of diffraction patterns from biological samples reported here represent an important step toward the potential of imaging single biomolecules at near-atomic resolution by combining single-particle diffraction with x-ray free electron lasers.

  5. 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.

  6. Speciation of chromium and sulfur in aerosols by rapid single-particle mass spectrometry

    SciTech Connect

    Neubauer, K.R.; Johnston, M.V.; Wexler, A.S.

    1994-12-31

    Two elements commonly found in industrial emissions are chromium and sulfur. In the atmosphere each element exists in two oxidation states which exhibit different health effects and/or reactivities. Cr(III) is an essential nutrient while Cr(VI) is corrosive and carcinogenic; as a result inhalation of Cr(VI) can cause lung cancer as well as erosion of the nasal septum. Sulfur(VI) in the form of methanesulfonic acid (MSA) is an important component of the global warming cycle while sulfur(IV) and other forms of S(VI) are important to acid deposition. Therefore the need exists to differentiate Cr(III) and Cr(VI) as well as S(IV) and S(VI) in the particulate phase. With conventional analytical techniques, aerosol particles must be collected over time and then prepared for analysis. These steps allow an opportunity for chemical transformation and oxidation state interconversions to occur. To overcome this problem, the authors use rapid single-particle mass spectrometry (RSMS).

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. Uncoating Mechanism of Carnation Mottle Virus Revealed by Cryo-EM Single Particle Analysis

    PubMed Central

    Wang, Chun-Yan; Zhang, Qin-Fen; Gao, Yuan-Zhu; Xie, Li; Li, Hong-Mei; Hong, Jian; Zhang, Chuan-Xi

    2015-01-01

    Genome uncoating is a prerequisite for the successful infection of plant viruses in host plants. Thus far, little is known about the genome uncoating of the Carnation mottle virus (CarMV). Here, we obtained two reconstructions of CarMV at pH7 in the presence (Ca-pH7) and absence (EDTA-pH7) of calcium ions by Cryo-EM single particle analysis, which achieved 6.4 Å and 8 Å resolutions respectively. Our results showed that chelation of the calcium ions under EDTA-pH7 resulted in reduced interaction between the subunits near the center of the asymmetric unit but not overall size change of the viral particles, which indicated that the role of the calcium ions in CarMV was not predominantly for the structural preservation. Part of the genomic RNA closest to the capsid was found to be located near the center of the asymmetric unit, which might result from the interaction between genomic RNA and Lys194 residues. Together with the electrostatic potential analysis on the inner surface of the asymmetric unit, the reduced interaction near the center of the asymmetric unit under EDTA-pH7 suggested that the genome release of CarMV might be realized through the center of the asymmetric unit. PMID:26442593

  13. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  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. Deblurring of Class-Averaged Images in Single-Particle Electron Microscopy

    PubMed Central

    Park, Wooram; Madden, Dean R.; Rockmore, Daniel N.; Chirikjian, Gregory S.

    2010-01-01

    This paper proposes a method for deblurring of class-averaged images in single-particle electron microscopy (EM). Since EM images of biological samples are very noisy, the images which are nominally identical projection images are often grouped, aligned and averaged in order to cancel or reduce the background noise. However, the noise in the individual EM images generates errors in the alignment process, which creates an inherent limit on the accuracy of the resulting class averages. This inaccurate class average due to the alignment errors can be viewed as the result of a convolution of an underlying clear image with a blurring function. In this work, we develop a deconvolution method that gives an estimate for the underlying clear image from a blurred class-averaged image using precomputed statistics of misalignment. Since this convolution is over the group of rigid body motions of the plane, SE(2), we use the Fourier transform for SE(2) in order to convert the convolution into a matrix multiplication in the corresponding Fourier space. For practical implementation we use a Hermite-function-based image modeling technique, because Hermite expansions enable lossless Cartesian-polar coordinate conversion using the Laguerre-Fourier expansions, and Hermite expansion and Laguerre-Fourier expansion retain their structures under the Fourier transform. Based on these mathematical properties, we can obtain the deconvolution of the blurred class average using simple matrix multiplication. Tests of the proposed deconvolution method using synthetic and experimental EM images confirm the performance of our method. PMID:20221416

  16. The effect of model fidelity on prediction of char burnout for single-particle coal combustion

    SciTech Connect

    McConnell, Josh; Sutherland, James C.

    2016-07-09

    In this study, practical simulation of industrial-scale coal combustion relies on the ability to accurately capture the dynamics of coal subprocesses while also ensuring the computational cost remains reasonable. The majority of the residence time occurs post-devolatilization, so it is of great importance that a balance between the computational efficiency and accuracy of char combustion models is carefully considered. In this work, we consider the importance of model fidelity during char combustion by comparing combinations of simple and complex gas and particle-phase chemistry models. Detailed kinetics based on the GRI 3.0 mechanism and infinitely-fast chemistry are considered in the gas-phase. The Char Conversion Kinetics model and nth-Order Langmuir–Hinshelwood model are considered for char consumption. For devolatilization, the Chemical Percolation and Devolatilization and Kobayashi-Sarofim models are employed. The relative importance of gasification versus oxidation reactions in air and oxyfuel environments is also examined for various coal types. Results are compared to previously published experimental data collected under laminar, single-particle conditions. Calculated particle temperature histories are strongly dependent on the choice of gas phase and char chemistry models, but only weakly dependent on the chosen devolatilization model. Particle mass calculations were found to be very sensitive to the choice of devolatilization model, but only somewhat sensitive to the choice of gas chemistry and char chemistry models. High-fidelity models for devolatilization generally resulted in particle temperature and mass calculations that were closer to experimentally observed values.

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

    PubMed Central

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

    2016-01-01

    Functionalization of quantum dots (QDs) with a single biomolecular tag using traditional approaches in bulk solution has met with limited success. DNA polyhedra consist of an internal void bounded by a well-defined three-dimensional structured surface. The void can house cargo and the surface can be functionalized with stoichiometric and spatial precision. Here, we show that monofunctionalized QDs can be achieved by encapsulating QDs inside DNA icosahedra and functionalizing the DNA shell with an endocytic ligand. We deployed the DNA-encapsulated QDs for real time imaging of three different endocytic ligands - folic acid, galectin-3 (Gal3) and the Shiga toxin B-subunit (STxB). Single particle tracking of Gal3 or STxB-functionalized, QD-loaded DNA icosahedra allows us to monitor compartmental dynamics along endocytic pathways. These DNA-encapsulated QDs that bear a unique stoichiometry of endocytic ligands represent a new class of molecular probes for quantitative imaging of endocytic receptor dynamics. PMID:27548358

  18. Orbital Single Particle Tracking on a commercial confocal microscope using piezoelectric stage feedback

    PubMed Central

    Lanzanò, Luca; Gratton, Enrico

    2014-01-01

    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. PMID:25419461

  19. Improved identification of primary biological aerosol particles using single-particle mass spectrometry

    DOE PAGES

    Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; ...

    2017-06-16

    Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology tomore » differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.« less

  20. Single-cell/Single-particle Irradiation Using Heavy-ion Microbeams

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yasuhiko

    Heavy charged particles transfer their energy to biological organisms through high-density ionization along the particle trajectories. The population of cells exposed to a very low dose of heavy-ion beams contains a few cells hit by a particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, some of the cells receive two or more events according to the Poisson distribution of ion injections. This fluctuation of particle trajectories through individual cells makes interpretation of radiological effects of heavy ions difficult. Furthermore, there has recently been an increasing interest in ionizing radiation-induced “bystander effects”, that is, radiation effects transmitted from hit cells to neighboring un-hit cells. Therefore, we have established a single-cell/single-particle irradiation system using a heavy-ion microbeam apparatus at JAEA-Takasaki to study radiobiological processes in hit cells and bystander cells exposed to low dose and low dose-rate high-LET radiations, in ways that cannot be achieved using conventional broad-field exposures.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  2. 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.

  3. Emission angle dependence of fission fragment spin: Effects of single particle spin and tilting mode

    NASA Astrophysics Data System (ADS)

    Datta, T.; Naik, H.; Dange, S. P.

    1995-06-01

    The high-spin yield fraction (HSF) for the fission product 132Im,g has been measured as a function of fragment emission angle (90° >=Θ>=10°) in the 237Np(α29 MeV,f) system. It was seen that the HSF for 132I or corresponding fragment (~=134I) spin initially decreases as emission angle decreases from 90° to ~=45° and then steadily increases at lower angles (Θ<45°). Contrary to the present observation in odd-Z 241Am fission, earlier we had observed that fragment spin continuously decreases to a limit with decrease in emission angle from 90° to 20° in even-even 242Pu fission. These data have been analyzed in the framework of the collective mode model invoking the effect of single particle spin. It is seen that for an odd-Z or A fissioning nucleus, angular variation of fragment spin could be accounted for on the basis of coupling between the odd nucleon spin (j>=k~=4ħ) projections and spin due to the collective rotational (tilting) degrees. Collective rotational degrees govern fragment spin for even-even fissioning nucleus.

  4. Differentiation of primary biological aerosol from mineral dust using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zawadowicz, M. A.; Froyd, K. D.; Perring, A. E.; Murphy, D. M.; Moehler, O.; Cziczo, D. J.

    2016-12-01

    The role of primary biological aerosol in cloud formation is uncertain. Measurements of biological aerosol abundance, especially at altitudes relevant to cirrus clouds, are scarce. Evidence of biological ice nucleation comes primarily from laboratory ice chamber studies using a limited number of highly-active species. Previous airborne single particle mass spectrometry studies have identified biological particles in ice cloud residuals. However, the methods from those studies have not been shown capable of differentiating biological aerosol from mineral dust. We have developed a robust method of differentiation using aerosol chemistry data collected by the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument by forming a database of atmospherically-relevant PALMS spectra from these aerosol types. We show that mineral dust is often confused with biological material and offer insights as to the reason for confusion. We further use PALMS flight deployments to estimate concentrations of biological aerosol both close to the surface and in the upper troposphere. This method is compared to established techniques of bioaerosol identification, such as Wideband Integrated Bioaerosol Sensor (WIBS) and electron microscopy. The results of this study support mineral dust to be the primary source of ice nucleating particles in the free troposphere.

  5. 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).

  6. 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.

  7. Longitudinal, transverse, and single-particle dynamics in liquid Zn: Ab initio study and theoretical analysis

    NASA Astrophysics Data System (ADS)

    del Rio, B. G.; González, L. E.

    2017-06-01

    We perform ab initio molecular dynamics simulations of liquid Zn near the melting point in order to study the longitudinal and transverse dynamic properties of the system. We find two propagating excitations in both of them in a wide range of wave vectors. This is in agreement with some experimental observations of the dynamic structure factor in the region around half the position of the main peak. Moreover, the two-mode structure in the transverse and longitudinal current correlation functions had also been previously observed in high pressure liquid metallic systems. We perform a theoretical analysis in order to investigate the possible origin of such two components by resorting to mode-coupling theories. They are found to describe qualitatively the appearance of two modes in the dynamics, but their relative intensities are not quantitatively reproduced. We suggest some possible improvements of the theory through the analysis of the structure of the memory functions. We also analyze the single-particle dynamics embedded in the velocity autocorrelation function, and explain its characteristics through mode-coupling concepts.

  8. Evidence for the intramolecular pleating model of fibrillin microfibril organisation from single particle image analysis.

    PubMed

    Lu, Yinhui; Holmes, David F; Baldock, Clair

    2005-05-27

    Fibrillin microfibrils endow mammalian connective tissues with elasticity and are fundamental for the deposition of elastin. The microfibrils are 57nm periodic supramolecular protein polymers with a mass of 2.4MDa per repeat. The detailed structure and organisation of most matrix assemblies is poorly understood due to their large size and complexity and it has proved a major challenge to define their structural organisation. Therefore, we have used low dose electron microscopy and single particle image analysis to study the structure of fibrillin microfibrils. Three novel features were detected: a globular feature that bridges the "arm" region, a double band of density crossing the microfibril and stain penetrating holes present in the interbead region, possibly produced by the removal of microfibril associated proteins in the purification procedure. Fine filaments of approximately 2.4nm diameter are resolved in the interbead region, which correspond to the reported diameter of the fibrillin molecule. Comparison of the stain exclusion pattern of microfibrils with the theoretical stain exclusion pattern of fibrillin packing models indicates that the intramolecular pleating model, where each fibrillin molecule is pleated within one microfibril period allowing extensibility by unpleating, has the best fit to the data.

  9. Particle interactions of fluticasone propionate and salmeterol xinafoate detected with single particle aerosol mass spectrometry (SPAMS).

    PubMed

    Jetzer, Martin; Morrical, Bradley; Fergenson, David; Imanidis, Georgios

    2017-08-29

    Particle co-associations between the active pharmaceutical ingredients fluticasone propionate and salmeterol xinafoate were examined in dry powder inhaled (DPI) and metered dose inhaled (MDI) combination products. Single Particle Aerosol Mass Spectrometry was used to investigate the particle interactions in Advair Diskus(®) (500/50 mcg) and Seretide(®) (125/25 mcg). A simple rules tree was used to identify each compound, either alone or co-associated at the level of the individual particle, using unique marker peaks in the mass spectra for the identification of each drug. High levels of drug particle co-association (fluticasone-salmeterol) were observed in the aerosols emitted from Advair Diskus(®) and Seretide(®). The majority of the detected salmeterol particles were found to be in co-association with fluticasone in both tested devices. Another significant finding was that rather coarse fluticasone particles (in DPI) and fine salmeterol particles (both MDI and DPI) were forming the particle co-associations. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Dynamic wetting: status and prospective of single particle based experiments and simulations.

    PubMed

    Cappelli, S; Xie, Q; Harting, J; de Jong, A M; Prins, M W J

    2015-09-25

    The fundamental molecular and microscopic properties of materials leading to dynamic wetting and relaxation effects have been subject to numerous studies in the past decades, but a thorough understanding is still missing. While most previous experiments utilize fluids deposited on planar substrates, this article focuses on an attractive alternative based on single colloidal particles: colloidal particles have the ability to strongly interact with fluid-fluid interfaces and the behavior strongly depends on the surface properties of the particles and the fluids used. Recent progress in the manipulation and synthesis of colloidal particles with well-defined surface properties and shapes makes them ideal candidates to probe the fundamental surface properties leading to dynamic wetting effects. In this paper we review and discuss the status of experimental and numerical techniques to characterize the dynamic wetting of single particles at fluid-fluid interfaces, with the aim to assist scientists and engineers in the design of new experimental techniques and particle-based (bio)analytical tools.

  11. Single particle EM studies of the Drosophila melanogaster origin recognition complex and evidence for DNA wrapping.

    PubMed

    Clarey, Megan G; Botchan, Michael; Nogales, Eva

    2008-12-01

    Hyperphosphorylation of the Drosophila melanogaster origin recognition complex (DmORC) by cyclin dependent kinases (CDKs) allows nucleotide binding but inhibits the ATPase activity of Orc1, and ablates the ATP-dependent interaction of ORC with DNA. Here we present single particle electron microscopy (EM) studies of ORC bound to nucleotide in both the dephosphorylated and hyper-phosphorylated states. 3D image reconstructions show that nucleotide binding gives rise to an analogous conformation independent of phosphorylation state. At the intermediate resolution achieved in our studies, ATP promotes changes along the toroidal core of the complex with negligible differences contributed by phosphorylation. Thus, hyperphosphorylation of DmORC does not induce meso-scale rearrangement of the ORC structure. To better understand ORC's role in origin remodeling, we performed atomic force microscopy (AFM) studies that show the contour length of a 688bp linear DNA fragment shortens by the equivalent of approximately 130bp upon ORC binding. This data, coupled with previous studies that showed a linking number change in circular DNA upon ORC binding, suggests that ORC may wrap the DNA in a manner akin to DnaA. Based on existing data and our structures, we propose a subunit arrangement for the AAA+ and winged helix domains, and in addition, speculate on a path of the 133bp of DNA around the ORC complex.

  12. Image processing for electron microscopy single-particle analysis using XMIPP.

    PubMed

    Scheres, Sjors H W; Núñez-Ramírez, Rafael; Sorzano, Carlos O S; Carazo, José María; Marabini, Roberto

    2008-01-01

    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.

  13. Achieving Size Independent Hit-Rate in Single Particle Mass Spectrometry

    SciTech Connect

    Zelenyuk, Alla; Yang, Juan; Imre, Dan G.; Choi, Eric Y.

    2009-04-01

    Recent improvements in single particle mass spectrometers make it possible to optically detect, size, and characterize the compositions of individual particles with diameters larger than a micron and smaller than 100 nm. Based on particle detection in two stages of optical detection these instruments generate a precisely timed trigger pulse, which is used to fire the ion generation laser or lasers. Practical experience shows that the wide size range results in small, but significant differences in laser trigger timing between small and large particles. If not treated, the instrument hit-rate becomes size dependent and instrument operator is forced to optimize the instrument for the desired size range, while having to contend with a lower hit-rate for the other. The present paper presents an analysis of the problem, demonstrating that size dependence of laser trigger timing stems from the differences in the particle position within the detection laser beam at the instant of detection. It shows that it is possible to compensate for these differences by generation a laser trigger delay coefficient for individual particles as a function of particle time of flight, i.e. its size. The study also shows that a single function can be used to characterize particles with a wide range of densities.

  14. 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.

  15. The single-particle density matrix of a quantum bright soliton from the coordinate Bethe ansatz

    NASA Astrophysics Data System (ADS)

    Ayet, Alex; Brand, Joachim

    2017-02-01

    We present a novel approach for computing reduced density matrices for superpositions of eigenstates of a Bethe-ansatz solvable model by direct integration of the wave function in coordinate representation. A diagrammatic approach is developed to keep track of relevant terms and identify symmetries, which helps to reduce the number of terms that have to be evaluated numerically. As a first application we compute with modest numerical resources the single-particle density matrix and its eigenvalues including the condensate fraction for a quantum bright soliton with up to N  =  10 bosons. The latter are constructed as superpositions of string-type Bethe-ansatz eigenstates of nonrelativistic bosons in one spatial dimension with attractive contact interaction. Upon delocalising the superposition in momentum space we find that the condensate fraction reaches maximum values larger than 97% with weak particle-number dependence in the range of particles studied. The presented approach is suitable for studying time-dependent problems and generalises to higher-order correlation functions.

  16. 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

  17. Single-particle spectral function of the Λ hyperon in finite nuclei

    NASA Astrophysics Data System (ADS)

    Vidaña, Isaac

    2017-02-01

    The spectral function of the Λ hyperon in finite nuclei is calculated from the corresponding Λ self-energy, which is constructed within a perturbative many-body approach using some of the hyperon-nucleon interactions of the Jülich and Nijmegen groups. Binding energies, wave functions and disoccupation numbers of different single-particle states are obtained for various hypernuclei from He5Λ to Pb209Λ. The agreement between the calculated binding energies and experimental data is qualitatively good. The small spin-orbit splitting of the p- , d- , f- and g-wave states is confirmed. The discrete and the continuum contributions of the single-Λ spectral function are computed. Their appearance is qualitatively similar to that of the nucleons. The Z-factor, that measures the importance of correlations, is also calculated. Our results show that its value is relatively large, indicating that the Λ hyperon is less correlated than nucleons. This is in agreement with the results obtained by other authors for the correlations of the Λ in infinite nuclear matter. The disoccupation numbers are obtained by integrating the spectral function over the energy. Our results show that the discrete contribution to the disoccupation number decreases when increasing the momentum of the Λ. This indicates that, in the production reactions of hypernuclei, the Λ hyperon is mostly formed in a quasi-free state.

  18. 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

  19. Initial evaluation of a direct detection device detector for single particle cryo-electron microscopy.

    PubMed

    Milazzo, Anna-Clare; Cheng, Anchi; Moeller, Arne; Lyumkis, Dmitry; Jacovetty, Erica; Polukas, James; Ellisman, Mark H; Xuong, Nguyen-Huu; Carragher, Bridget; Potter, Clinton S

    2011-12-01

    We report on initial results of using a new direct detection device (DDD) for single particle reconstruction of vitreous ice embedded specimens. Images were acquired on a Tecnai F20 at 200keV and a nominal magnification of 29,000×. This camera has a significantly improved signal to noise ratio and modulation transfer function (MTF) at 200keV compared to a standard CCD camera installed on the same microscope. Control of the DDD has been integrated into Leginon, an automated data collection system. Using GroEL as a test specimen, we obtained images of ∼30K particles with the CCD and the DDD from the same specimen sample using essentially identical imaging conditions. Comparison of the maps reconstructed from the CCD images and the DDD images demonstrates the improved performance of the DDD. We also obtained a 3D reconstruction from ∼70K GroEL particles acquired using the DDD; the quality of the density map demonstrates the potential of this new recording device for cryoEM data acquisition.

  20. Single-particle EM reveals extensive conformational variability of the Ltn1 E3 ligase.

    PubMed

    Lyumkis, Dmitry; Doamekpor, Selom K; Bengtson, Mario H; Lee, Joong-Won; Toro, Tasha B; Petroski, Matthew D; Lima, Christopher D; Potter, Clinton S; Carragher, Bridget; Joazeiro, Claudio A P

    2013-01-29

    Ltn1 is a 180-kDa E3 ubiquitin ligase that associates with ribosomes and marks certain aberrant, translationally arrested nascent polypeptide chains for proteasomal degradation. In addition to its evolutionarily conserved large size, Ltn1 is characterized by the presence of a conserved N terminus, HEAT/ARM repeats predicted to comprise the majority of the protein, and a C-terminal catalytic RING domain, although the protein's exact structure is unknown. We used numerous single-particle EM strategies to characterize Ltn1's structure based on negative stain and vitreous ice data. Two-dimensional classifications and subsequent 3D reconstructions of electron density maps show that Ltn1 has an elongated form and presents a continuum of conformational states about two flexible hinge regions, whereas its overall architecture is reminiscent of multisubunit cullin-RING ubiquitin ligase complexes. We propose a model of Ltn1 function based on its conformational variability and flexibility that describes how these features may play a role in cotranslational protein quality control.

  1. 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.

  2. Coarse-grained single-particle dynamics in two-dimensional solids and liquids.

    PubMed

    Silbermann, Jörg R; Schoen, Martin; Klapp, Sabine H L

    2008-07-01

    We consider the dynamics of a single tagged particle in a two-dimensional system governed by Lennard-Jones interactions. Previous work based on the Mori-Zwanzig projection operator formalism has shown that the single-particles dynamics can be described via a generalized Langevin equation (GLE) which is exact within the harmonic approximation, that is, for a low-temperature solid [J. M. Deutch and R. Silbey, Phys. Rev. A 3, 2049 (1971)]. In the present work we explore to what an extent the GLE reproduces the effective dynamics under thermodynamic conditions where the harmonic approximation is no longer justified. To this end we compute characteristic time autocorrelation functions for the tagged particle in molecular dynamics simulations of the full system and compare these functions with those obtained from solving the GLE. At low temperatures we find excellent agreement between both data sets. Deviations emerge at higher temperatures which are, however, surprisingly small even in the high-temperature liquid phase.

  3. Ab initio Approach to Effective Single-Particle Energies in Doubly Closed Shell Nuclei

    SciTech Connect

    Duguet, T.

    2012-01-01

    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. Effects of macromolecular crowding on intracellular diffusion from a single particle perspective

    PubMed Central

    Hoshino, Masaru

    2010-01-01

    Compared to biochemical reactions taking place in relatively well-defined aqueous solutions in vitro, the corresponding reactions happening in vivo occur in extremely complex environments containing only 60–70% water by volume, with the remainder consisting of an undefined array of bio-molecules. In a biological setting, such extremely complex and volume-occupied solution environments are termed ‘crowded’. Through a range of intermolecular forces and pseudo-forces, this complex background environment may cause biochemical reactions to behave differently to their in vitro counterparts. In this review, we seek to highlight how the complex background environment of the cell can affect the diffusion of substances within it. Engaging the subject from the perspective of a single particle’s motion, we place the focus of our review on two areas: (1) experimental procedures for conducting single particle tracking experiments within cells along with methods for extracting information from these experiments; (2) theoretical factors affecting the translational diffusion of single molecules within crowded two-dimensional membrane and three-dimensional solution environments. We conclude by discussing a number of recent publications relating to intracellular diffusion in light of the reviewed material. PMID:21088688

  5. 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.

  6. Single Particle Extinction and Scattering allows novel optical characterization of aerosols

    NASA Astrophysics Data System (ADS)

    Mariani, Federico; Bernardoni, Vera; Riccobono, Francesco; Vecchi, Roberta; Valli, Gianluigi; Sanvito, Tiziano; Paroli, Bruno; Pullia, Alberto; Potenza, Marco A. C.

    2017-08-01

    We apply to aerosols the optical method of Single Particle Extinction and Scattering recently proposed for characterizing liquid suspensions and specifically adapted to the aim. It provides simultaneous measurements of the real and imaginary parts of the field scattered in the forward direction by single airborne particles passing through a tightly focused laser beam. The intensity of transmitted light is collected in the forward direction, thus realizing a self-reference interferometric scheme relying on the fundamentals of the optical theorem. A high frequency (20 MS/s), extended dynamics (12 bits) sampling is performed by a cheap segmented photodiode, and a specific pulse shape analysis is exploited to validate the signals against a precise mathematical model. We show that accessing two independent physical quantities allows to exploit physical models to recover the aerosol size distribution from the measurement of the refractive index, either real or even complex. Laboratory measurements have been performed with polydisperse aerosols made of water droplets and NaCl in the submicron range, and the system has been accurately characterized. Examples of measurements of graphite nanoparticles and Pyrethrum smoke are shown. Limitations are discussed.

  7. A Toolbox for Ab Initio 3-D Reconstructions in Single-particle Electron Microscopy

    PubMed Central

    Voss, Neil R; Lyumkis, Dmitry; Cheng, Anchi; Lau, Pick-Wei; Mulder, Anke; Lander, Gabriel C; Brignole, Edward J; Fellmann, Denis; Irving, Christopher; Jacovetty, Erica L; Leung, Albert; Pulokas, James; Quispe, Joel D; Winkler, Hanspeter; Yoshioka, Craig; Carragher, Bridget; Potter, Clinton S

    2010-01-01

    Structure determination of a novel macromolecular complex via single-particle electron microscopy depends upon overcoming the challenge of establishing a reliable 3-D reconstruction using only 2-D images. There are a variety of strategies that deal with this issue, but not all of them are readily accessible and straightforward to use. We have developed a “toolbox” of ab initio reconstruction techniques that provide several options for calculating 3-D volumes in an easily managed and tightly controlled work-flow that adheres to standard conventions and formats. This toolbox is designed to streamline the reconstruction process by removing the necessity for bookkeeping, while facilitating transparent data transfer between different software packages. It currently includes procedures for calculating ab initio reconstructions via random or orthogonal tilt geometry, tomograms, and common lines, all of which have been tested using the 50S ribosomal subunit. Our goal is that the accessibility of multiple independent reconstruction algorithms via this toolbox will improve the ease with which models can be generated, and provide a means of evaluating the confidence and reliability of the final reconstructed map. PMID:20018246

  8. 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

  9. Optimized method for black carbon analysis in ice and snow using the Single Particle Soot Photometer

    NASA Astrophysics Data System (ADS)

    Wendl, I. A.; Menking, J. A.; Färber, R.; Gysel, M.; Kaspari, S. D.; Laborde, M. J. G.; Schwikowski, M.

    2014-08-01

    In this study we attempt to optimize the method for measuring black carbon (BC) in snow and ice using a Single Particle Soot Photometer (SP2). Beside the previously applied ultrasonic (CETAC) and Collison-type nebulizers we introduce a jet (Apex Q) nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and Apex Q require small sample volumes (a few milliliters) which makes them suitable for ice core analysis. The Apex Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100-1000 nm. The CETAC has the advantage that air and liquid flows can be monitored continuously. All nebulizer-types require a calibration with BC standards for the determination of the BC mass concentration in unknown aqueous samples. We found Aquadag to be a suitable material for preparing calibration standards. Further, we studied the influence of different treatments for fresh discrete snow and ice samples as well as the effect of storage. The results show that samples are best kept frozen until analysis. Once melted, they should be sonicated for 25 min, immediately analyzed while being stirred and not be refrozen.

  10. Optimized method for black carbon analysis in ice and snow using the Single Particle Soot Photometer

    NASA Astrophysics Data System (ADS)

    Wendl, I. A.; Menking, J. A.; Färber, R.; Gysel, M.; Kaspari, S. D.; Laborde, M. J. G.; Schwikowski, M.

    2014-03-01

    In this study we attempt to optimize the method for measuring black carbon (BC) in snow and ice using a single particle soot photometer (SP2). Beside the previously applied ultrasonic (CETAC) and Collison-type nebulizers we introduce a jet (APEX-Q) nebulizer to aerosolize the aqueous sample for SP2 analysis. Both CETAC and APEX-Q require small sample volumes (few milliliters) which makes them suitable for ice core analysis. The APEX-Q shows the least size-dependent nebulizing efficiency in the BC particle diameter range of 100-1000 nm. The CETAC has the advantage that air and liquid flows can be monitored continuously. All nebulizer-types require a calibration with BC standards for the determination of the BC mass concentration in unknown aqueous samples. We found Aquadag to be a suitable material for preparing calibration standards. Further, we studied the influence of different treatments for fresh discrete snow and ice samples as well as the effect of storage. The results show that samples are best kept frozen until analysis. Once melted, they should be sonicated for 25 min, immediately analyzed while being stirred and not be refrozen.

  11. Super-resolution imaging with mid-IR photothermal microscopy on the single particle level

    NASA Astrophysics Data System (ADS)

    Li, Zhongming; Kuno, Masaru; Hartland, Gregory

    2015-08-01

    Photothermal microscopy has achieved single molecule sensitivity. However, the analytes are usually restricted to be natural absorbers in the visible light region. Mid-infrared (MIR) imaging, on the other hand, provides a wealth of information, but encounters difficulties of diffraction-limited spatial resolution and scarcity of ideal detectors. Here we present Mid-IR photothermal heterodyne imaging (MIR-PHI) microscopy as a high sensitivity, super-resolution mid-IR imaging technique. In MIR-PHI, a tunable Mid- IR pulsed laser at 150 kHz is used to excite a micron sized particle. Energy relaxation creates a temperature gradient around the particle, changing the refractive index of the surrounding solvent and creating a thermal lens. A collinear, counter propagating probe beam (a 532 nm CW laser) is modified by the thermal lens and generates a super-resolution photothermal image. We studied 1.1 μm polystyrene beads at the single particle level using this technique. Various solvents with different heat capacities and refractive indices are tested for the best image contrast. The wide applicability and potentially high sensitivity of this technique make it promising for biological imaging and identification.

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

    PubMed

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

    2017-04-25

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

  13. Evolution of single-particle strength in neutron-rich 71Cu

    NASA Astrophysics Data System (ADS)

    Morfouace, P.; Franchoo, S.; Sieja, K.; Matea, I.; Nalpas, L.; Niikura, M.; Sánchez-Benítez, A. M.; Stefan, I.; Assié, M.; Azaiez, F.; Beaumel, D.; Boissinot, S.; Borcea, C.; Borcea, R.; Burgunder, G.; Cáceres, L.; De Séréville, N.; Dombrádi, Zs.; Elseviers, J.; Fernández-Domínguez, B.; Gillibert, A.; Giron, S.; Grévy, S.; Hammache, F.; Kamalou, O.; Lapoux, V.; Lefebvre, L.; Lepailleur, A.; Louchart, C.; Marquinez-Duran, G.; Martel, I.; Matta, A.; Mengoni, D.; Napoli, D. R.; Recchia, F.; Scarpaci, J.-A.; Sohler, D.; Sorlin, O.; Stanoiu, M.; Stodel, C.; Thomas, J.-C.; Vajta, Zs.

    2015-12-01

    The strength functions of the πf5/2, πp3/2 and πf7/2 orbitals in neutron-rich 71Cu were obtained in a 72Zn(d,3He)71Cu proton pick-up reaction in inverse kinematics using a radioactive beam of 72Zn at 38 MeV/u. A dedicated set-up was developed to overcome the experimental challenges posed by the low cross section of the reaction and the low energy of the outgoing 3He particles. The excitation-energy spectrum was reconstructed and spectroscopic factors were obtained after analysis of the angular distributions with the finite-range Distorted-Wave Born Approximation (DWBA). The results show that unlike for the πf5/2 orbital and contrary to earlier interpretation, the πf7/2 single-particle strength distribution is not appreciably affected by the addition of neutrons beyond N = 40.

  14. Improved identification of primary biological aerosol particles using single-particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zawadowicz, Maria A.; Froyd, Karl D.; Murphy, Daniel M.; Cziczo, Daniel J.

    2017-06-01

    Measurements of primary biological aerosol particles (PBAP), especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS) has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture) using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04-2 % of particles in the 200-3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36-56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust-biological mixtures.

  15. 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.

  16. Electromagnetic strength of neutron and proton single-particle halo nuclei

    NASA Astrophysics Data System (ADS)

    Typel, S.; Baur, G.

    2005-09-01

    Electromagnetic strength functions of halo nuclei exhibit universal features that can be described in terms of characteristic scale parameters. For a nucleus with nucleon + core structure the reduced transition probability, as determined, e.g., by Coulomb dissociation experiments, shows a typical shape that depends on the nucleon separation energy and the orbital angular momenta in the initial and final states. The sensitivity to the final-state interaction (FSI) between the nucleon and the core can be studied systematically by varying the strength of the interaction in the continuum. In the case of neutron + core nuclei analytical results for the reduced transition probabilities are obtained by introducing the effective-range expansion. The scaling with the relevant parameters is found explicitly. General trends are observed by studying several examples of neutron + core and proton + core nuclei in a single-particle model assuming Woods-Saxon potentials. Many important features of the neutron halo case can be obtained from a square-well model. Rather simple analytical formulas are found. The nucleon-core interaction in the continuum affects the determination of astrophysical S factors at zero energy in the method of asymptotic normalisation coefficients (ANC). It is also relevant for the extrapolation of radiative capture cross sections to low energies.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  18. 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.

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

    PubMed

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

    2016-12-01

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

  20. 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.