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Sample records for crystallization phenomena accion

  1. Accions

    NASA Astrophysics Data System (ADS)

    Choi, Kang-Sin; Nilles, Hans Peter; Ramos-Sánchez, Saúl; Vaudrevange, Patrick K. S.

    2009-05-01

    Axion fields provide the most elegant solution to the strong CP problem. In string compactifications it is difficult to obtain an axion whose decay constant is consistent with current cosmological bounds. We examine this question in theories with accidental U(1) symmetries that appear as low energy remnants of discrete symmetries. We refer to the axion-like particles from the spontaneous breakdown of these symmetries as accions. In such systems, the accion decay constant depends on the vacuum configuration and can be lowered to fit the bounds. Furthermore, we find that such accions with consistent decay constant can be embedded in special vacua of Z6-II orbifold models with realistic features.

  2. Crystal Melting and Wall Crossing Phenomena

    NASA Astrophysics Data System (ADS)

    Yamazaki, Masahito

    2010-02-01

    This paper summarizes recent developments in the theory of Bogomol'nyi-Prasad-Sommerfield (BPS) state counting and the wall crossing phenomena, emphasizing in particular the role of the statistical mechanical model of crystal melting. This paper is divided into two parts, which are closely related to each other. In the first part, we discuss the statistical mechanical model of crystal melting counting BPS states. Each of the BPS state contributing to the BPS index is in one-to-one correspondence with a configuration of a molten crystal, and the statistical partition function of the melting crystal gives the BPS partition function. We also show that smooth geometry of the Calabi-Yau manifold emerges in the thermodynamic limit of the crystal. This suggests a remarkable interpretation that an atom in the crystal is a discretization of the classical geometry, giving an important clue as to the geometry at the Planck scale.In the second part we discuss the wall crossing phenomena. Wall crossing phenomena states that the BPS index depends on the value of the moduli of the Calabi-Yau manifold, and jumps along real codimension one subspaces in the moduli space. We show that by using type IIA/M-theory duality, we can provide a simple and an intuitive derivation of the wall crossing phenomena, furthermore clarifying the connection with the topological string theory. This derivation is consistent with another derivation from the wall crossing formula, motivated by multi-centered BPS extremal black holes. We also explain the representation of the wall crossing phenomena in terms of crystal melting, and the generalization of the counting problem and the wall crossing to the open BPS invariants.

  3. Crystal Melting and Wall Crossing Phenomena

    NASA Astrophysics Data System (ADS)

    Yamazaki, Masahito

    This paper summarizes recent developments in the theory of Bogomol'nyi-Prasad-Sommerfield (BPS) state counting and the wall crossing phenomena, emphasizing in particular the role of the statistical mechanical model of crystal melting. This paper is divided into two parts, which are closely related to each other. In the first part, we discuss the statistical mechanical model of crystal melting counting BPS states. Each of the BPS states contributing to the BPS index is in one-to-one correspondence with a configuration of a molten crystal, and the statistical partition function of the melting crystal gives the BPS partition function. We also show that smooth geometry of the Calabi-Yau manifold emerges in the thermodynamic limit of the crystal. This suggests a remarkable interpretation that an atom in the crystal is a discretization of the classical geometry, giving an important clue as such to the geometry at the Planck scale. In the second part, we discuss the wall crossing phenomena. Wall crossing phenomena states that the BPS index depends on the value of the moduli of the Calabi-Yau manifold, and jumps along real codimension one subspaces in the moduli space. We show that by using type IIA/M-theory duality, we can provide a simple and an intuitive derivation of the wall crossing phenomena, furthermore clarifying the connection with the topological string theory. This derivation is consistent with another derivation from the wall crossing formula, motivated by multicentered BPS extremal black holes. We also explain the representation of the wall crossing phenomena in terms of crystal melting, and the generalization of the counting problem and the wall crossing to the open BPS invariants.

  4. Protein Crystallization: Specific Phenomena and General Insights on Crystallization Kinetics

    NASA Technical Reports Server (NTRS)

    Rosenberger, F.

    1998-01-01

    Experimental and simulation studies of the nucleation and growth kinetics of proteins have revealed phenomena that are specific for macromolecular crystallization, and others that provide a more detailed understanding of solution crystallization in general. The more specific phenomena, which include metastable liquid-liquid phase separations and gelation prior to solid nucleation, are due to the small ratio of the intermolecular interaction-range to the size of molecules involved. The apparently more generally applicable mechanisms include the cascade-like formation of macrosteps, as an intrinsic morphological instability that roots in the coupled bulk transport and nonlinear interface kinetics in systems with mixed growth rate control. Analyses of this nonlinear response provide (a) criteria for the choice of bulk transport conditions to minimize structural defect formation, and (b) indications that the "slow" protein crystallization kinetics stems from the mutual retardation of growth steps.

  5. Polyelectrolyte effects on the crystallization phenomena of the lithium carbonate

    NASA Astrophysics Data System (ADS)

    Watamura, Hiroto; Marukawa, Hironobu; Hirasawa, Izumi

    2013-06-01

    Anionic polyelectrolyte effects on the lithium carbonate crystallization phenomena were investigated. Li2CO3 crystals were obtained by reactive crystallization with seed crystals. Polyelectrolytes were dissolved into the reactive field before the reaction. Obtained crystals were observed with scanning electron microscopy (SEM) and crystal size and agglomeration degree were measured by the SEM images. The results show that Li2CO3 crystallized different shape and size from absence of polyelectrolyte in those reactive fields. Especially polyacrylic acid (PAA) improved on the agglomeration of the crystals and shaped them high aspect needles. Thus other experimental conditions including PAA molecular weight and concentration, reaction time, supersaturation by Li concentration were investigated in addition. As a result, obtained crystals were not different in each PAA molecular weight reactive fields. Meanwhile PAA concentration has optimum range. Li2CO3 formed less agglomeration and higher aspect around 1 g/l. In the concentration, Li2CO3 did not agglomerate regardless of aging time and Li concentration. Moreover crystals became rectangle shape in higher Li concentration.(020) face intensity of the rectangle shape crystals increased according to XRD pattern. PAA affected the facial growth. These results may provide a method of morphological change and clearly crystallization of Li2CO3.

  6. Certain relativistic phenomena in crystal optics

    NASA Astrophysics Data System (ADS)

    Chee-Seng, Lim

    1980-01-01

    Relativistic unsteady phenomena are established for a crystalline medium with unaligned sets of permittivity and permeability principal axes, but incorporating a compounded uniaxiality about some nonprincipal direction. All effects originate from a suddenly activated, arbitrarily oriented, maintained line current conducted with a finite velocity v. Integral representations studied in another paper (Chee-Seng) are applied. The original coordinate system is subjected to a series of rotational and translational, scaled and unscaled transformations. No specific coordinate frame is strictly adhered to. Instead, it is often expedient and advantageous to exploit several reference frames simultaneously in the course of the analysis and interpretations. The electric field is directly related to a net scalar field Δ involving another scalar Ψ and its complement Ψ¯ which can be deduced from Ψ; Ψ and Ψ¯ are associated with two expanding, inclined ellipsoidal wavefronts ξ and ξ¯; these are cocentered at the current origin and touch each other twice along the uniaxis. Elsewhere, ξ leads ξ¯. For a source current faster than ξ:vt ∈ extξ, Ψ≢0 within a finite but growing ''ice-cream cone'' domain, its nontrivial composition being χ-1/2 inside ξ and 2χ-1/2 inside part of a tangent cone from the advancing current edge vt to, and terminating at, ξ; the function χ vanishes along such a tangent cone. Alternatively, for a source current slower than ξ:vt∈ intξ, if vt is avoided, χ≳0 everywhere, while Ψ=χ-1/2 inside ξ but vanishes identically outside ξ. However, the crucial scalar field Δ depends on three separate current-velocity regimes. Over a slow regime: vt∈ intξ¯, Δ is nontrivial inside ξ wherein it is discontinuous across ξ¯. Over an intermediate regime: vt ∈ intξ extξ¯, Δ takes four distinct forms on 12 adjacent domains bounded by ξ, ξ¯ and a double-conical tangent surface linking vt to ξ¯. But for a fast regime: vt∈ ext

  7. Transport phenomena of crystal growth—heat and mass transfer

    NASA Astrophysics Data System (ADS)

    Rudolph, Peter

    2010-07-01

    Selected fundamentals of transport processes and their importance for crystal growth are given. First, principal parameters and equations of heat and mass transfer, like thermal flux, radiation and diffusion are introduced. The heat- and mass- balanced melt-solid and solution-solid interface velocities are derived, respectively. The today's significance of global numeric simulation for analysis of thermo-mechanical stress and related dislocation dynamics within the growing crystal is shown. The relation between diffusion and kinetic regime is discussed. Then, thermal and solutal buoyancy-driven and Marangoni convections are introduced. Their important interplay with the diffusion boundary layer, component and particle incorporation as well as morphological interface stability is demonstrated. Non-steady crystallization phenomena (striations) caused by convective fluctuations are considered. Selected results of global 3D numeric modeling are shown. Finally, advanced methods to control heat and mass transfer by external forces, such as accelerated container rotation, ultrasonic vibration and magnetic fields are discussed.

  8. Nonlinear pulse propagation phenomena in ion-doped dielectric crystals

    NASA Astrophysics Data System (ADS)

    Demeter, Gabor; Kis, Zsolt; Hohenester, Ulrich

    2012-03-01

    We theoretically analyze pulse propagation in a medium of inhomogeneously broadened two-level quantum systems, which have a vibrational degree of freedom with respect to the center-of-mass coordinate. This system mimics local mode oscillations of rare-earth-metal-ion dopants in dielectric crystals that are coupled to electronic transitions. We show the emergence of various nonlinear optical phenomena, such as self-induced transparency or the nonlinear interaction between two pulses coupling to different electrovibrational transitions. Interaction between the pulses makes it possible to generate various Raman sidebands of the incident fields and to tune the location where they are generated. We also demonstrate controlled population transfer between electrovibrational states of the ions at specific points along the propagation axis. Similarities and differences between our results and other pulse propagation phenomena of few-level quantum systems are discussed.

  9. Interference phenomena at backscattering by ice crystals of irregular shape

    NASA Astrophysics Data System (ADS)

    Konoshonkin, Alexander V.; Kustova, Natalia V.; Borovoi, Anatoli G.

    2015-11-01

    It is shown that light backscattering by hexagonal ice crystals of cirrus clouds is formed by both diffraction and interference phenomena. Diffraction determines the angular width of the backscattering peak and interference produces the interference rings inside the peak. By use of a simplest model for distortion of the pristine hexagonal shape, we show that the shape distortion leads to both oscillations of the scattering (Mueller) matrix within the backscattering peak and to a strong increase of the depolarization, color, and lidar ratios needed for interpretation of lidar signals.

  10. Interference phenomena at backscattering by ice crystals of cirrus clouds.

    PubMed

    Borovoi, Anatoli; Kustova, Natalia; Konoshonkin, Alexander

    2015-09-21

    It is shown that light backscattering by hexagonal ice crystals of cirrus clouds is formed within the physical-optics approximation by both diffraction and interference phenomena. Diffraction determines the angular width of the backscattering peak and interference produces the interference rings inside the peak. By use of a simple model for distortion of the pristine hexagonal shape, we show that the shape distortion leads to both oscillations of the scattering (Mueller) matrix within the backscattering peak and to a strong increase of the depolarization, color, and lidar ratios needed for interpretation of lidar signals.

  11. Premelting phenomena in pseudo-binary ionic crystals.

    PubMed

    Matsunaga, Shigeki

    2010-04-21

    The theory of the premelting phenomena in ionic crystals on the basis of the concept of the heterophase fluctuation has been applied to the pseudo-binary ionic crystals, KCl-NaCl, AgBr-AgCl and AgBr-CuBr systems. Molecular dynamics simulations (MD) have been performed to examine the ionic configurations in their premelting region in the vicinity of their melting points. Liquid-like clusters have been observed in the results of MD utilizing the Lindemann instability condition. The sizes of liquid-like clusters have been estimated by theory and MD. The characteristics of the dynamical behavior of ions in the premelting region have been examined by the mean square displacement and the velocity correlation functions.

  12. Thin Film Mediated Phase Change Phenomena: Crystallization, Evaporation and Wetting

    NASA Technical Reports Server (NTRS)

    Wettlaufer, John S.

    1998-01-01

    We focus on two distinct materials science problems that arise in two distinct microgravity environments: In space and within the space of a polymeric network. In the former environment, we consider a near eutectic alloy film in contact with its vapor which, when evaporating on earth, will experience compositionally induced buoyancy driven convection. The latter will significantly influence the morphology of the crystallized end member. In the absence of gravity, the morphology will be dominated by molecular diffusion and Marangoni driven viscous flow, and we study these phenomena theoretically and experimentally. The second microgravity environment exists in liquids, gels, and other soft materials where the small mass of individual molecules makes the effect of gravity negligible next to the relatively strong forces of intermolecular collisions. In such materials, an essential question concerns how to relate the molecular dynamics to the bulk rheological behavior. Here, we observe experimentally the diffusive motion of a single molecule in a single polymer filament, embedded within a polymer network and find anomalous diffusive behavior.

  13. Physical phenomena related to crystal growth in the space environment

    NASA Technical Reports Server (NTRS)

    Chu, T. L.

    1973-01-01

    The mechanism of crystal growth which may be affected by the space environment was studied. Conclusions as to the relative technical and scientific advantages of crystal growth in space over earth bound growth, without regard to economic advantage, were deduced. It was concluded that the crucibleless technique will most directly demonstrate the unique effects of the greatly reduced gravity in the space environment. Several experiments, including crucibleless crystal growth using solar energy and determination of diffusion coefficients of common dopants in liquid silicon were recommended.

  14. Observations of dynamic stall phenomena using liquid crystal coatings

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.

    1991-01-01

    Novel, shear stress-sensitive/temperature-insensitive liquid crystal coatings have been applied to the surface of an oscillating airfoil in order to ascertain the unsteady fluid physics associated with the dynamic-stall process. Surface microtufts and laser sheet/smoke-particle flow visualization were used to compare the liquid-crystal results. Boundary-layer transition and turbulent separation locations were measured as a function of geometric angle of attack. The results obtained are compared with Eppler (1980) aerodynamic design code predictions.

  15. Observations of dynamic stall phenomena using liquid crystal coatings

    NASA Astrophysics Data System (ADS)

    Reda, Daniel C.

    1991-02-01

    Novel, shear stress-sensitive/temperature-insensitive liquid crystal coatings have been applied to the surface of an oscillating airfoil in order to ascertain the unsteady fluid physics associated with the dynamic-stall process. Surface microtufts and laser sheet/smoke-particle flow visualization were used to compare the liquid-crystal results. Boundary-layer transition and turbulent separation locations were measured as a function of geometric angle of attack. The results obtained are compared with Eppler (1980) aerodynamic design code predictions.

  16. Protein Crystals Grow Purer in Space: Physics of Phenomena

    NASA Technical Reports Server (NTRS)

    Chernov, Alex A.

    2000-01-01

    This presentation will summarize the quantitative experimental and theoretical results obtained by B.R. Thomas, P.G. Vekilov, D.C. Carter, A.M. Holmes, W.K. Widierow and the Author, the team with expertise in physics, biochemistry, crystallography and engineering. Impurities inhomogeneously trapped by a growing crystal - e.g., producing sectorial structure and/or striations - may induce macroscopic internal stress in it if an impurity molecule has slightly (less than 10%) different shape or volume than the regular one(s) they replace. We tested for the first time plasticity and measured Young modulus E of the triclinic, not cross-linked lysozyme by triple point bending technique. Triclinic lysozyme crystals are purely elastic with E similar or equal to 1/5 (raised dot) 10 (exp 9) partial derivative yn/sq cm. The strength limit, sigma (sub c) similar or equal to 10 (exp -3)E similar or equal to Epsilon (sub c), where sigma (sub c) and epsilon (sub c) are critical stress and strain, respectively. Scaling E and sigma (sub c) with the lattice spacing suggests similar binding stiffness in inorganic and biomolecular crystals. The inhomogeneous internal stress may be resolved in these brittle crystals either by cracking or by creation of misoriented mosaic blocks during, not after growth. If each impurity molecule induces in the lattice elementary strain epsilon (sub 0) similar or equal to 3 (raised dot) 10 (exp -2) (this is maximal elementary strain that can arise at the supersaturation DELTA mu/kT similar or equal to 2 and macroscopic molecular concentration difference between subsequent macrolayers or growth sectors is partial derivativeC similar or equal to 5 (raised dot) 10 (exp -3), the internal strain epsilon similar or equal to epsilon (sub 0) partial derivative C similar or equal to 10 (exp -4). Mosaic misorientation resolving such strain is approximately 30 arcsec. Tenfold increase of impurity concentration may cause cracking. Estimates of stress in an isometric

  17. Modeling of Macroscopic/Microscopic Transport and Growth Phenomena in Zeolite Crystal Solutions Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Gatsonis, Nikos A.; Alexandrou, Andreas; Shi, Hui; Ongewe, Bernard; Sacco, Albert, Jr.

    1999-01-01

    Crystals grown from liquid solutions have important industrial applications. Zeolites, for instance, a class of crystalline aluminosilicate materials, form the backbone of the chemical process industry worldwide, as they are used as adsorbents and catalysts. Many of the phenomena associated with crystal growth processes are not well understood due to complex microscopic and macroscopic interactions. Microgravity could help elucidate these phenomena and allow the control of defect locations, concentration, as well as size of crystals. Microgravity in an orbiting spacecraft could help isolate the possible effects of natural convection (which affects defect formation) and minimize sedimentation. In addition, crystals will stay essentially suspended in the nutrient pool under a diffusion-limited growth condition. This is expected to promote larger crystals by allowing a longer residence time in a high-concentration nutrient field. Among other factors, the crystal size distribution depends on the nucleation rate and crystallization. These two are also related to the "gel" polymerization/depolymerization rate. Macroscopic bulk mass and flow transport and especially gravity, force the crystals down to the bottom of the reactor, thus forming a sedimentation layer. In this layer, the growth rate of the crystals slows down as crystals compete for a limited amount of nutrients. The macroscopic transport phenomena under certain conditions can, however, enhance the nutrient supply and therefore, accelerate crystal growth. Several zeolite experiments have been performed in space with mixed results. The results from our laboratory have indicated an enhancement in size of 30 to 70 percent compared to the best ground based controls, and a reduction of lattice defects in many of the space grown crystals. Such experiments are difficult to interpret, and cannot be easily used to derive empirical or other laws since many physical parameters are simultaneously involved in the process

  18. Recent Advances in Colloidal and Interfacial Phenomena Involving Liquid Crystals

    PubMed Central

    Bai, Yiqun; Abbott, Nicholas L.

    2011-01-01

    This article describes recent advances in several areas of research involving the interfacial ordering of liquid crystals (LCs). The first advance revolves around the ordering of LCs at bio/chemically functionalized surfaces. Whereas the majority of past studies of surface-induced ordering of LCs have involved surfaces of solids that present a limited diversity of chemical functional groups (surfaces at which van der Waals forces dominate surface-induced ordering), recent studies have moved to investigate the ordering of LCs on chemically complex surfaces. For example, surfaces decorated with biomolecules (e.g. oligopeptides and proteins) and transition metal ions have been investigated, leading to an understanding of the roles that metal-ligand coordination interactions, electrical double-layers, acid-base interactions, and hydrogen bonding can have on the interfacial ordering of LCs. The opportunity to create chemically-responsive LCs capable of undergoing ordering transitions in the presence of targeted molecular events (e.g., ligand exchange around a metal center) has emerged from these fundamental studies. A second advance has focused on investigations of the ordering of LCs at interfaces with immiscible isotropic fluids, particularly water. In contrast to prior studies of surface-induced ordering of LCs on solid surfaces, LC- aqueous interfaces are deformable and molecules at these interfaces exhibit high levels of mobility and thus can reorganize in response to changes in interfacial environment. A range of fundamental investigations involving these LC-aqueous interfaces have revealed that (i) the spatial and temporal characteristics of assemblies formed from biomolecular interactions can be reported by surface-driven ordering transitions in the LCs, (ii) the interfacial phase behaviour of molecules and colloids can be coupled to (and manipulated via) the ordering (and nematic elasticity) of LCs, and (iii) confinement of LCs leads to unanticipated size

  19. Simulation of Transport Phenomena in Aluminum Nitride Single-Crystal Growth

    SciTech Connect

    de Almeida, VF

    2002-05-16

    The goal of this project is to apply advanced computer-aided modeling techniques for simulating coupled radiation transfer present in the bulk growth of aluminum nitride (AlN) single-crystals. Producing and marketing high-quality single-crystals of AlN is currently the focus of Crystal IS, Inc., which is engaged in building a new generation of substrates for electronic and optical-electronic devices. Modeling and simulation of this company's proprietary innovative processing of AlN can substantially improve the understanding of physical phenomena, assist design, and reduce the cost and time of research activities. This collaborative work supported the goals of Crystal IS, Inc. in process scale-up and fundamental analysis with promising computational tools.

  20. Simulation of Transport Phenomena in Aluminum Nitride Single-Crystal Growth

    SciTech Connect

    de Almeida, V F

    2002-04-03

    The goal of this project is to apply advanced computer-aided modeling techniques for simulating coupled radiation transfer present in the bulk growth of aluminum nitride (AlN) single-crystals. Producing and marketing high-quality single-crystals of AlN is currently the focus of Crystal IS, Inc., which is engaged in building a new generation of substrates for electronic and optical-electronic devices. Modeling and simulation of this company's proprietary innovative processing of AlN can substantially improve the understanding of physical phenomena, assist design, and reduce the cost and time of research activities. This collaborative work supported the goals of Crystal IS, Inc. in process scale-up and fundamental analysis with promising computational tools.

  1. Transport phenomena of growth-in-gel zeolite crystallization in microgravity

    NASA Technical Reports Server (NTRS)

    Zhang, H.; Ostrach, S.; Kamotani, Y.

    1993-01-01

    Secondary nucleation (SN) due to crystal sedimentation has been believed to be one of the major effects that causes smaller sizes of final zeolite crystals. The present investigation indicates that, in a reactor, this gravity-induced SN occurs only within a white opaque column termed the gel portion. Under normal gravity this portion shrinks to the bottom of the hydrothermal reactor, leaving a clear portion of solution at the top, due to depletion of the flocculated gel particles. Solution phase nucleation and crystallization is assumed and a correlation for the shrinkage is therefore derived, which shows good agreement with experimental observations. A non-dimensional parameter is suggested as a criterion for the occurrence of SN. Based on the parameter whether or not microgravity is beneficial to zeolite growth is discussed. Also, the growth mechanism and the transport phenomena in the absence of gravity are discussed.

  2. Colloidal crystals and water: Perspectives on liquid-solid nanoscale phenomena in wet particulate media.

    PubMed

    Gallego-Gómez, Francisco; Morales-Flórez, Víctor; Morales, Miguel; Blanco, Alvaro; López, Cefe

    2016-08-01

    Solid colloidal ensembles inherently contain water adsorbed from the ambient moisture. This water, confined in the porous network formed by the building submicron spheres, greatly affects the ensemble properties. Inversely, one can benefit from such influence on collective features to explore the water behavior in such nanoconfinements. Recently, novel approaches have been developed to investigate in-depth where and how water is placed in the nanometric pores of self-assembled colloidal crystals. Here, we summarize these advances, along with new ones, that are linked to general interfacial water phenomena like adsorption, capillary forces, and flow. Water-dependent structural properties of the colloidal crystal give clues to the interplay between nanoconfined water and solid fine particles that determines the behavior of ensembles. We elaborate on how the knowledge gained on water in colloidal crystals provides new opportunities for multidisciplinary study of interfacial and nanoconfined liquids and their essential role in the physics of utmost important systems such as particulate media.

  3. Explicitly Solvable Model of the Charge Carriers' Phenomena in Isotropic Conducting Crystals

    NASA Astrophysics Data System (ADS)

    Budzak, Yaroslav S.; Wacławski, Tadeusz

    2017-01-01

    In this paper, a theoretical analysis of the kinetic properties of the isotropic conducting crystals is presented. The general formulas for these kinetic properties are expressed in terms of the Fermi integrals. These integrals were obtained using methods of statistical ensembles with varying number of particles and the Gibbs's grand canonical distribution. The determination of the scattering function and the exploration of its relation with the mobility of the current carriers inside these crystals have been made. Together with the results of theoretical analysis of the scattering function and its relation with the current carriers' mobility, these formulas constitute the mathematical model of the charge carriers' transport phenomena in conducting crystals (where a non-parabolic energy spectrum is described by Kane's formula) and provide algorithms for the calculation of these properties.

  4. Crystal Ice Formation of Solution and Its Removal Phenomena around Vertical Cooled Cylinder

    NASA Astrophysics Data System (ADS)

    Hirata, Tetsuo; Ishikawa, Masaaki; Akutsu, Nobuaki

    Experimental and analytical studies for freezing phenomena of ethylene glycol solution around a vertical cooled polyvinyl-chloride cylinder have been performed. It is found that the crystal ice formed around the vertical cylinder is removed from the cylinder surface due to buoyancy force acting on the crystal ice. The crystal ice slides along the cylinder surface due to buoyancy force and grows in a shape of tube by joining with the neighbour ice. It is shown that the onset of ice removal condition is related to the heat flux at the cylinder surface when the latent heat of fusion is discharged with freezing, and that the heat flux ratio of 'from the cylinder surface into the cylinder' to 'from the cylinder surface to the solution' is an important parameter for the onset conditions. The ice removal occurs easily for short cylinders than for long ones.

  5. Explicitly Solvable Model of the Charge Carriers' Phenomena in Isotropic Conducting Crystals

    NASA Astrophysics Data System (ADS)

    Budzak, Yaroslav S.; Wacławski, Tadeusz

    2017-04-01

    In this paper, a theoretical analysis of the kinetic properties of the isotropic conducting crystals is presented. The general formulas for these kinetic properties are expressed in terms of the Fermi integrals. These integrals were obtained using methods of statistical ensembles with varying number of particles and the Gibbs's grand canonical distribution. The determination of the scattering function and the exploration of its relation with the mobility of the current carriers inside these crystals have been made. Together with the results of theoretical analysis of the scattering function and its relation with the current carriers' mobility, these formulas constitute the mathematical model of the charge carriers' transport phenomena in conducting crystals (where a non-parabolic energy spectrum is described by Kane's formula) and provide algorithms for the calculation of these properties.

  6. Coarsening Dynamics of Inclusions and Thermocapillary Phenomena in Smectic Liquid Crystal Bubbles

    NASA Astrophysics Data System (ADS)

    Park, Cheol; Maclennan, Joseph; Glaser, Matthew; Clark, Noel; Trittel, Torsten; Eremin, Alexey; Stannarius, Ralf; Tin, Padetha; Hall, Nancy

    The Observation and Analysis of Smectic Islands in Space (OASIS) project comprises a series of experiments that probe interfacial and hydrodynamic behavior of thin spherical-bubbles of smectic liquid crystal in microgravity. Smectic films are the thinnest known stable condensed phase structures, making them ideal for studies of two-dimensional (2D) coarsening dynamics and thermocapillary phenomena in microgravity. The OASIS flight hardware was launched on SpaceX-6 in April 2015 and experiments were carried out on the International Space Station using four different smectic A and C liquid crystal materials in separate sample chambers. We will describe the behavior of collective island dynamics on the bubbles, including temperature gradient-induced themomigration, and the diffusion and coalescence-driven coarsening dynamics of island emulsions in microgravity. This work was supported by NASA Grant No. NNX-13AQ81G, and NSF MRSEC Grants No. DMR-0820579 and DMR-1420736.

  7. Convection phenomena during the growth of sodium chlorate crystals from solution

    NASA Technical Reports Server (NTRS)

    Chen, P. S.; Shlichta, P. J.; Wilcox, W. R.; Lefever, R. A.

    1979-01-01

    The paper examines convection phenomena during the growth of sodium chlorate crystals from solution. Schlieren observations of sodium chlorate crystals suspended in supersaturated solutions showed that with increase in supersaturation or crystal size, the boundary layer on the side faces was stable while the top boundary layer and emerging plume changed from stable to partially oscillatory. The transition was a function of the Grashof number, Gr sub top, and the crystal height. Gr sub top correlated with plume width, number of streamlines, eddy density, and plume velocity, but the oscillation period correlated with the weight increase growth rate. The mass transfer rate, the linear growth rate, and growth of vertical and horizontal faces are discussed, and an estimate of boundary layer flow vs growth rate for near-critical stable convection indicated that growth of side faces depleted over half of the excess solute in the boundary layer. Impulse energies greatly in excess of the threshold value caused transient separation of the boundary layer on the top face, and plume wavering due to background-induced fluid motion was observed only at the lowest supersaturations.

  8. Theoretical study of production of unique glasses in space. [kinetic relationships describing nucleation and crystallization phenomena

    NASA Technical Reports Server (NTRS)

    Larsen, D. C.; Sievert, J. L.

    1975-01-01

    The potential of producing the glassy form of selected materials in the weightless, containerless nature of space processing is examined through the development of kinetic relationships describing nucleation and crystallization phenomena. Transformation kinetics are applied to a well-characterized system (SiO2), an excellent glass former (B2O3), and a poor glass former (Al2O3) by conventional earth processing methods. Viscosity and entropy of fusion are shown to be the primary materials parameters controlling the glass forming tendency. For multicomponent systems diffusion-controlled kinetics and heterogeneous nucleation effects are considered. An analytical empirical approach is used to analyze the mullite system. Results are consistent with experimentally observed data and indicate the promise of mullite as a future space processing candidate.

  9. Nematic liquid crystals confined in microcapillaries for imaging phenomena at liquid-liquid interfaces.

    PubMed

    Zhong, Shenghong; Jang, Chang-Hyun

    2015-09-21

    Here, we report the development of an experimental system based on liquid crystals (LCs) confined in microcapillaries for imaging interfacial phenomena. The inner surfaces of the microcapillaries were modified with octadecyltrichlorosilane to promote an escaped-radial configuration of LCs. We checked the optical appearance of the capillary-confined LCs under a crossed polarizing microscope and determined their arrangement based on side and top views. We then placed the capillary-confined LCs in contact with non-surfactant and surfactant solutions, producing characteristic textures of two bright lines and a four-petal shape, respectively. We also evaluated the sensitivity, stability, and reusability of the system. Our imaging system was more sensitive than previously reported LC thin film systems. The textures formed in microcapillaries were stable for more than 120 h and the capillaries could be reused at least 10 times. Finally, we successfully applied our system to image the interactions of phospholipids and bivalent metal ions. In summary, we developed a simple, small, portable, sensitive, stable, and reusable experimental system that can be broadly applied to monitor liquid-liquid interfacial phenomena. These results provide valuable information for designs using confined LCs as chemoresponsive materials in optical sensors.

  10. The numerical study on large bandwidth photonic crystal waveguide with slow light phenomena

    NASA Astrophysics Data System (ADS)

    Yan, Ming-Bao; Fu, Zhen-Tang; Wang, Wei-Yu

    2013-02-01

    In this paper, two novel types of semi-slow light photonic crystal waveguide with large transmission bandwidth obtained by shifting the boundaries of a W1 waveguide in the direction of light propagation are presented. One includes air rings localized at only one side of the line defect and the other replaces the holes at each side of the waveguide by the uniform air rings which are constructed by the homocentric square dielectric rod inserted into the air holes. The structure produces unusual "n-type" transmission spectrum depending on the different parameters such as inner radius of air ring, dielectric constant of square dielectric rod, etc. It is shown that the transmission spectra of the two structures are completely different from each other. A versatile control of light propagation with large normalized bandwidth and slow light phenomena can be obtained using a unique geometrical parameter. Numerical simulation by the finite-difference time-domain (FDTD) method demonstrates the propagation of the broadband pulse.

  11. Diffraction phenomena in spontaneous and stimulated radiation by relativistic particles in crystals (Review)

    SciTech Connect

    Baryshevsky, V.G. ); Dubovskaya, I.Ya. )

    1991-12-01

    This report discusses: the dispersion characteristics of parametric x-ray radiation (PXR) and diffraction radiation of oscillator; cooperative effects in x-radiation by charged particles in crystals; and diffraction x-radiation by relativistic oscillator.

  12. The transport phenomena during the growth of ZnTe crystal by the temperature gradient solution growth technique

    NASA Astrophysics Data System (ADS)

    Yin, Liying; Jie, Wanqi; Wang, Tao; Zhou, Boru; Yang, Fan

    2017-03-01

    A numerical model is developed to simulate the temperature field, the thermosolutal convection, the solute segregation and the growth interface morphology during the growth of ZnTe crystal from Te rich solution by the temperature gradient solution growth (TGSG) technique. Effects of the temperature gradient on the transport phenomena, the growth interface morphology and the growth rate are examined. The influences of the latent heat and the thermal conductivity of ZnTe crystal on the transport phenomena and the growth interface are also discussed. We find that the mass transfer of ZnTe in the solution is very slow because of the low diffusion coefficient and the lack of mixing in the lower part of the solution. During the growth, dilute solution with high density and low growth temperature accumulates in the central region of the growth interface, making the growth interface change into two distinct parts. The inner part is very concave, while the outer part is relatively flat. Growth conditions in front of the two parts of the growth interface are different. The crystalline quality of the inner part of the ingot is predicted to be worse than that of the outer part. High temperature gradient can significantly increase the growth rate, and avoid the diffusion controlled growth to some extent.

  13. Translation-rotation coupling, phase transitions, and elastic phenomena in orientationally disordered crystals

    NASA Astrophysics Data System (ADS)

    Lynden-Bell, R. M.; Michel, K. H.

    1994-07-01

    Many of the properties of orientationally disordered crystals are profoundly affected by the coupling (known as translation-rotation coupling) between translation displacements and molecular orientation. The consequences of translation-rotation coupling depend on molecular and crystal symmetry, and vary throughout the Brillouin zone. One result is an indirect coupling between the orientations of different molecules, which plays an important role in the order/disorder phase transition, especially in ionic orientationally disordered crystals. Translation-rotation coupling also leads to softening of elastic constants and affects phonon spectra. This article describes the theory of the coupling from the point of view of the microscopic Hamiltonian and the resulting Landau free energy. Considerable emphasis is placed on the restrictions due to symmetry as these are universal and can be used to help one's qualitative understanding of experimental observations. The application of the theory to phase transitions is described. The softening of elastic constants is discussed and shown to be universal. However, anomalies associated with the order/disorder phase transition are shown to be restricted to cases in which the symmetry of the order parameter satisfies certain conditions. Dynamic effects on phonon spectra are described and finally the recently observed dielectric behavior of ammonium compounds is discussed. Throughout the article examples from published experiments are used to illustrate the application of the theory including well known examples such as the alkali metal cyanides and more recently discovered orientationally disordered crystals such as the fullerite, C60.

  14. In-plane time-harmonic elastic wave motion and resonance phenomena in a layered phononic crystal with periodic cracks.

    PubMed

    Golub, Mikhail V; Zhang, Chuanzeng

    2015-01-01

    This paper presents an elastodynamic analysis of two-dimensional time-harmonic elastic wave propagation in periodically multilayered elastic composites, which are also frequently referred to as one-dimensional phononic crystals, with a periodic array of strip-like interior or interface cracks. The transfer matrix method and the boundary integral equation method in conjunction with the Bloch-Floquet theorem are applied to compute the elastic wave fields in the layered periodic composites. The effects of the crack size, spacing, and location, as well as the incidence angle and the type of incident elastic waves on the wave propagation characteristics in the composite structure are investigated in details. In particular, the band-gaps, the localization and the resonances of elastic waves are revealed by numerical examples. In order to understand better the wave propagation phenomena in layered phononic crystals with distributed cracks, the energy flow vector of Umov and the corresponding energy streamlines are visualized and analyzed. The numerical results demonstrate that large energy vortices obstruct elastic wave propagation in layered phononic crystals at resonance frequencies. They occur before the cracks reflecting most of the energy transmitted by the incoming wave and disappear when the problem parameters are shifted from the resonant ones.

  15. Improved opportunities for the investigation of crystal growth phenomena on Space Station Freedom

    NASA Astrophysics Data System (ADS)

    Wargo, M. J.

    1993-09-01

    Investigation of gravity as an experimental variable during crystal growth of electronic and photonic materials is expected to be significantly enhanced by the extended availability of the microgravity environment aboard Space Station Freedom. Experiments studying liquid/solid and vapor/solid phase transformations using the Crystal Growth Furnace were conducted during the first of the U.S. Microgravity Laboratory series of Space Shuttle flights. The increased time available for experiments on Space Station coupled with the quiescent environment expected during the ground-tended phase will permit scientists to conduct experiments which are not possible at present. These include studies which are both comprehensive and require processing times which are in excess of that available on today's carriers.

  16. Flux Pinning Phenomena in Electron Irradiated Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Single Crystals

    NASA Astrophysics Data System (ADS)

    Giapintzakis, John Konstantinos

    1992-01-01

    It has been shown that 1 MeV electron irradiation to a typical dose Phi~ 1times 10^{19} cm^{ -2} results in an enhancement of the critical current density in twinned and untwinned YBa_2 Cu_3O_{7 -delta} single crystals. Values up to two times the preirradiation J_{c} at 10 K and 1 T are observed. The J _{c} enhancement is accompanied by a dramatic increase of the irreversibility field. A threshold incident electron energy (E_{ t}~ 0.5 MeV) is found above which flux pinning enhancement is observed. The data indicated that the electron radiation-induced defects are effective pinning centers only for the orientation H parallel c-axis. In-situ TEM studies in the HVEM suggest that the pinning centers must be smaller than 20 A. A comparison of the electron irradiation results with those of proton irradiation experiments indicate a lower magnitude of enhancement of J_{c} at 10 K and 2 T for the electron case. The probable explanation is the difference in the energy spectra of the PKAs produced by the two types of irradiation. GdBa_2Cu_3O_{7-delta } and EuBa_2Cu_3O _{7-delta} single crystals irradiated with 0.6 MeV electrons displayed similar flux pinning enhancements as YBa_2Cu _3O_{7-delta} crystals, indicating that Y displacements are not primary flux pinners. The evidence from annealing studies suggests that the primary pinning center produced by the electron irradiation is not associated with the oxygen in the Cu-O chains. Instead, a consistent interpretation of the data suggests that the primary pinning defect is most likely based on the displacement of a copper atom from the CuO_2 plane. In order to account for the complete enhancement of J_{c} other pinning mechanisms aside from point defects, such as small point defect clusters, should be considered.

  17. Structural Properties, Order–Disorder Phenomena, and Phase Stability of Orotic Acid Crystal Forms

    PubMed Central

    2016-01-01

    Orotic acid (OTA) is reported to exist in the anhydrous (AH), monohydrate (Hy1), and dimethyl sulfoxide monosolvate (SDMSO) forms. In this study we investigate the (de)hydration/desolvation behavior, aiming at an understanding of the elusive structural features of anhydrous OTA by a combination of experimental and computational techniques, namely, thermal analytical methods, gravimetric moisture (de)sorption studies, water activity measurements, X-ray powder diffraction, spectroscopy (vibrational, solid-state NMR), crystal energy landscape, and chemical shift calculations. The Hy1 is a highly stable hydrate, which dissociates above 135 °C and loses only a small part of the water when stored over desiccants (25 °C) for more than one year. In Hy1, orotic acid and water molecules are linked by strong hydrogen bonds in nearly perfectly planar arranged stacked layers. The layers are spaced by 3.1 Å and not linked via hydrogen bonds. Upon dehydration the X-ray powder diffraction and solid-state NMR peaks become broader, indicating some disorder in the anhydrous form. The Hy1 stacking reflection (122) is maintained, suggesting that the OTA molecules are still arranged in stacked layers in the dehydration product. Desolvation of SDMSO, a nonlayer structure, results in the same AH phase as observed upon dehydrating Hy1. Depending on the desolvation conditions, different levels of order–disorder of layers present in anhydrous OTA are observed, which is also suggested by the computed low energy crystal structures. These structures provide models for stacking faults as intergrowth of different layers is possible. The variability in anhydrate crystals is of practical concern as it affects the moisture dependent stability of AH with respect to hydration. PMID:26741914

  18. Flow alignment phenomena in liquid crystals studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Sarman, Sten; Laaksonen, Aatto

    2009-10-01

    The flow alignment of a nematic liquid crystal has been studied as a function of temperature, beginning at high temperature in the nematic phase and down to the nematic-smectic A phase transition. The alignment angle is obtained by estimating the twist viscosities by nonequilibrium molecular dynamics (NEMD) methods. These estimates are cross-checked by evaluating the corresponding equilibrium fluctuation relations. As a further comparison, shear flow simulations are carried out by application of the SLLOD equations of motion (so named because of their close relationship to the Doll's equation of motion, which can be derived from the Doll's tensor Hamiltonian), whereby the alignment angle is obtained directly. All these methods give consistent results for the alignment angle. At low temperatures near the nematic-smectic A transition the system becomes flow unstable. In this region the alignment angle has been calculated as a function of time.

  19. Temperature-dependent ordering phenomena in single crystals of germanium antimony tellurides

    SciTech Connect

    Urban, Philipp; Schneider, Matthias N.; Oeckler, Oliver

    2015-07-15

    The temperature-dependent behavior of quenched single-crystalline (GeTe){sub n}Sb{sub 2}Te{sub 3} (n~2.8, n~5 and n~11) was investigated by semiquantitative modeling of diffuse X-ray scattering. The structure at room temperature exhibits trigonal twin domains, each comprising a stacking-disordered sequence of distorted rocksalt-type slabs with variable thicknesses. Ge and Sb share the cation position and vacancies are partially ordered in defect layers (van der Waals gaps) between the slabs. The average structure determined with resonant diffraction data corresponds to a rocksalt-type structure whose cation position is split along the stacking direction. Upon heating, cation ordering leads to a metastable superstructure of the rocksalt type at ~400 °C, which transforms to a rocksalt-type high-temperature phase with randomly distributed cations and vacancies at ~500 °C; this structure was also refined using resonant diffraction. Cooling at high or intermediate rates does not yield the long-range ordered phase, but directly leads to the twinned disordered phase. - Graphical abstract: Development of the diffraction patterns of (GeTe){sub ~11}Sb{sub 2}Te{sub 3} upon heating; the insets symbolically sketch the real structure at the corresponding temperatures. - Highlights: • The structure of disordered (GeTe){sub n}Sb{sub 2}Te{sub 3} is described as a function of temperature. • Structural changes are tracked by modeling diffuse X-ray scattering. • Quenched crystals exhibit distorted NaCl-type slabs with different thicknesses. • Vacancy ordering upon heating leads to a metastable superstructure of the NaCl type. • Further heating leads to an undistorted disordered NaCl-type high-temperature phase.

  20. Directional asymmetry of the nonlinear wave phenomena in a three-dimensional granular phononic crystal under gravity.

    PubMed

    Merkel, A; Tournat, V; Gusev, V

    2014-08-01

    We report the experimental observation of the gravity-induced asymmetry for the nonlinear transformation of acoustic waves in a noncohesive granular phononic crystal. Because of the gravity, the contact precompression increases with depth inducing space variations of not only the linear and nonlinear elastic moduli but also of the acoustic wave dissipation. We show experimentally and explain theoretically that, in contrast to symmetric propagation of linear waves, the amplitude of the nonlinearly self-demodulated wave depends on whether the propagation of the waves is in the direction of the gravity or in the opposite direction. Among the observed nonlinear processes, we report frequency mixing of the two transverse-rotational modes belonging to the optical band of vibrations and propagating with negative phase velocities, which results in the excitation of a longitudinal wave belonging to the acoustic band of vibrations and propagating with positive phase velocity. We show that the measurements of the gravity-induced asymmetry in the nonlinear acoustic phenomena can be used to compare the in-depth distributions of the contact nonlinearity and of acoustic absorption.

  1. Directional asymmetry of the nonlinear wave phenomena in a three-dimensional granular phononic crystal under gravity

    NASA Astrophysics Data System (ADS)

    Merkel, A.; Tournat, V.; Gusev, V.

    2014-08-01

    We report the experimental observation of the gravity-induced asymmetry for the nonlinear transformation of acoustic waves in a noncohesive granular phononic crystal. Because of the gravity, the contact precompression increases with depth inducing space variations of not only the linear and nonlinear elastic moduli but also of the acoustic wave dissipation. We show experimentally and explain theoretically that, in contrast to symmetric propagation of linear waves, the amplitude of the nonlinearly self-demodulated wave depends on whether the propagation of the waves is in the direction of the gravity or in the opposite direction. Among the observed nonlinear processes, we report frequency mixing of the two transverse-rotational modes belonging to the optical band of vibrations and propagating with negative phase velocities, which results in the excitation of a longitudinal wave belonging to the acoustic band of vibrations and propagating with positive phase velocity. We show that the measurements of the gravity-induced asymmetry in the nonlinear acoustic phenomena can be used to compare the in-depth distributions of the contact nonlinearity and of acoustic absorption.

  2. Mujeres en Accion: Design and Baseline Data

    PubMed Central

    Fleury, Julie; Perez, Adriana; Belyea, Michael; Castro, Felipe G.

    2015-01-01

    The majority of programs designed to promote physical activity in older Hispanic women includes few innovative theory-based interventions that address cultural relevant strategies. The purpose of this report is to describe the design and baseline data for Mujeres en Accion, a physical activity intervention to increase regular physical activity, and cardiovascular health outcomes among older Hispanic women. Mujeres en Accion [Women in Action for Health], a 12 month randomized controlled trial to evaluate the effectiveness of a social support physical activity intervention in midlife and older Hispanic women. This study tests an innovative intervention, Mujeres en Accion, and includes the use of a theory-driven approach to intervention, explores social support as a theoretical mediating variable, use of a Promotora model and a Community Advisory group to incorporate cultural and social approaches and resources, and use of objective measures of physical activity in Hispanic women. PMID:21298400

  3. Transport phenomena in the crystallization of lysozyme by osmotic dewatering and liquid-liquid diffusion in low gravity

    NASA Technical Reports Server (NTRS)

    Todd, Paul; Sportiello, Michael G.; Gregory, Derek; Cassanto, John M.; Alvarado, Ulises A.; Ostroff, Robert; Korszun, Z. R.

    1993-01-01

    Two methods of protein crystallization, osmotic dewatering and liquid-liquid diffusion, like the vapor diffusion (hanging-drop and sessile-drop) methods allow a gradual approach to supersaturation conditions. The crystallization of hen egg-white lysozyme, an extensively characterized protein crystal, in the presence of sodium chloride was used as an experimental model with which to compare these two methods in low gravity and in the laboratory. Comparisons of crystal growth rates by the two methods under the two conditions have, to date, indicated that the rate of crystal growth by osmotic dewatering is nearly the same in low gravity and on the ground, while much faster crystal growth rates can be achieved by the liquid-liquid diffusion method in low gravity.

  4. Investigation of primary nucleation phenomena of acetylsalicylic acid crystals induced by ultrasonic irradiation—ultrasonic energy needed to activate primary nucleation

    NASA Astrophysics Data System (ADS)

    Miyasaka, Etsuko; Ebihara, Satomi; Hirasawa, Izumi

    2006-09-01

    The purpose of our study is to clarify ultrasonic primary nucleation phenomena for controlling final product size by adjusting the number of primary nuclei. In our previous study, the effect of ultrasonic irradiation on the number of nuclei was investigated under the same supersaturated condition, as a result two novel phenomena were observed. First, there is a region where ultrasonic irradiation inhibits primary nucleation. Second, a specific amount of energy is needed to activate primary nucleation. From this result, it was expected that the ultrasonic energy needed to activate primary nucleation has a certain relationship to the energy necessary to form a stable nucleus. Therefore, we investigated the following: whether ultrasonic irradiation inhibits and activates primary nucleation at various degrees of supersaturation, whether final crystal size relates to the number of nuclei, and whether the ultrasonic energy needed to activate primary nucleation relates to the energy necessary to form a stable nucleus. First, we found that ultrasonic irradiation inhibits and activates primary nucleation at various supersaturated degrees. Second, we found that final crystal size increases or decreases depending on the number of nuclei. Therefore, it was indicated that ultrasonic energy could yield the desired crystal size by inducing suitable nucleation. Third, we found that the ultrasonic energy needed to activate primary nucleation decreases with a decrease in the energy necessary to form a stable nucleus. From this, we can propose criteria for determining the effect of ultrasonic irradiation on primary nucleation by showing diagrams correlating Δ Gcrit with Ecrit.

  5. Coherent phenomena in terahertz 2D plasmonic structures: strong coupling, plasmonic crystals, and induced transparency by coupling of localized modes

    NASA Astrophysics Data System (ADS)

    Dyer, Gregory C.; Aizin, Gregory R.; Allen, S. James; Grine, Albert D.; Bethke, Don; Reno, John L.; Shaner, Eric A.

    2014-05-01

    The device applications of plasmonic systems such as graphene and two dimensional electron gases (2DEGs) in III-V heterostructures include terahertz detectors, mixers, oscillators and modulators. These two dimensional (2D) plasmonic systems are not only well-suited for device integration, but also enable the broad tunability of underdamped plasma excitations via an applied electric field. We present demonstrations of the coherent coupling of multiple voltage tuned GaAs/AlGaAs 2D plasmonic resonators under terahertz irradiation. By utilizing a plasmonic homodyne mixing mechanism to downconvert the near field of plasma waves to a DC signal, we directly detect the spectrum of coupled plasmonic micro-resonator structures at cryogenic temperatures. The 2DEG in the studied devices can be interpreted as a plasmonic waveguide where multiple gate terminals control the 2DEG kinetic inductance. When the gate tuning of the 2DEG is spatially periodic, a one-dimensional finite plasmonic crystal forms. This results in a subwavelength structure, much like a metamaterial element, that nonetheless Bragg scatters plasma waves from a repeated crystal unit cell. A 50% in situ tuning of the plasmonic crystal band edges is observed. By introducing gate-controlled defects or simply terminating the lattice, localized states arise in the plasmonic crystal. Inherent asymmetries at the finite crystal boundaries produce an induced transparency-like phenomenon due to the coupling of defect modes and crystal surface states known as Tamm states. The demonstrated active control of coupled plasmonic resonators opens previously unexplored avenues for sensitive direct and heterodyne THz detection, planar metamaterials, and slow-light devices.

  6. Paranormal phenomena

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    1996-08-01

    Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

  7. Anatase-TiO2 Nanomaterials: Morphological/Size Dependence of the Crystallization and Phase Behavior Phenomena

    SciTech Connect

    Fernandez-Garcia,M.; Wang, X.; Belver, C.; Hanson, J.; Rodriguez, J.

    2007-01-01

    Nanoparticulated TiO{sub 2} materials with anatase structure were synthesized by using a microemulsion method. Three different syntheses with varying surfactant-to-water molar ratio ({omega}) were used to obtain amorphous solid precipitates at room temperature. The structural characteristics of these solid precursors were studied by using X-ray absorption structure (X-ray absorption near-edge structure and extended X-ray absorption fine structure) and Raman spectroscopies, which showed that all lack 3D (tridimensional) order but contain a different degree of 2D-confined connectivity. While heating such solid precursors under dry air, marked differences appeared in the phase behavior; the onset temperature for anatase crystallization increases ca. 150 {sup o}C while the {omega} parameter decreases and only one of the samples shows the anatase-to-rutile transformation below 900 {sup o}C. In all cases, the crystallization of the anatase structure does not follow a traditional nucleation and growth mechanism and its analysis using the Avrami formalism gives conclusive evidence of a surface nucleation-dominated process. This appears as a distinctive feature of anatase-TiO{sub 2} nanomaterials, far from the corresponding behavior of microsized or bulk materials. After nucleation, the grain growth of anatase nanoparticles was found to follow the kinetic equation D{sup 2}-D{sub 0}{sup 2} = k{sub 0} exp(-E{sub a}/RT), where the activation energy is a function of several structural properties of the solid materials mainly related to the hydration characteristics of the surface layer. A combined in situ X-ray diffraction/Raman/infrared study aimed to unveil the physical basis of the phase behavior and to interpret key variables allowing control of the crystallization mechanism and morphological properties, particularly primary particle size, in the nanometer regime.

  8. Transport Phenomena.

    ERIC Educational Resources Information Center

    Shah, D. B.

    1984-01-01

    Describes a course designed to achieve a balance between exposing students to (1) advanced topics in transport phenomena, pointing out similarities and differences between three transfer processes and (2) common methods of solving differential equations. (JN)

  9. Colloidal Phenomena.

    ERIC Educational Resources Information Center

    Russel, William B.; And Others

    1979-01-01

    Described is a graduate level engineering course offered at Princeton University in colloidal phenomena stressing the physical and dynamical side of colloid science. The course outline, reading list, and requirements are presented. (BT)

  10. Anomalous laser deflection phenomena based on the interaction of electro-optic and graded refractivity effect in Cu:KTN crystal

    NASA Astrophysics Data System (ADS)

    Wang, Xuping; Liu, Bing; Yang, Yuguo; Zhang, Yuanyuan; Lv, Xianshun; Hong, Guanglie; Shu, Rong; Yu, Haohai; Wang, Jiyang

    2014-12-01

    In this paper, we report an abnormal laser deflection phenomena based on quadratic electro-optic effect in copper doped KTN crystal. Cu:KTa0.62Nb0.38O3 block with size a×b×c = 2.8mm×2.6mm×12.5mm was used as beam deflection element. 75mrad beam deflection angle were observed under 1KV voltage when the laser beam across the c direction of the sample at room temperature. The special features of our experiment are that the direction of laser beam deflect perpendicular to the electric field direction, and the angular size and direction of the deflection beam remain unchanged when the electric field direction reverse. We believe that the interaction of graded refractivity and electro-optic effect leads to these special features. Besides of the special deflection mode, the deflection efficiency of our experiment also reached the world advanced level.

  11. Transport Phenomena.

    ERIC Educational Resources Information Center

    McCready, Mark J.; Leighton, David T.

    1987-01-01

    Discusses the problems created in graduate chemical engineering programs when students enter with a wide diversity of understandings of transport phenomena. Describes a two-semester graduate transport course sequence at the University of Notre Dame which focuses on fluid mechanics and heat and mass transfer. (TW)

  12. Solution‐crystallization and related phenomena in 9,9‐dialkyl‐fluorene polymers. II. Influence of side‐chain structure

    PubMed Central

    Perevedentsev, Aleksandr; Stavrinou, Paul N.; Smith, Paul

    2015-01-01

    ABSTRACT Solution‐crystallization is studied for two polyfluorene polymers possessing different side‐chain structures. Thermal analysis and temperature‐dependent optical spectroscopy are used to clarify the nature of the crystallization process, while X‐ray diffraction and scanning electron microscopy reveal important differences in the resulting microstructures. It is shown that the planar‐zigzag chain conformation termed the β‐phase, which is observed for certain linear‐side‐chain polyfluorenes, is necessary for the formation of so‐called polymer‐solvent compounds for these polymers. Introduction of alternating fluorene repeat units with branched side‐chains prevents formation of the β‐phase conformation and results in non‐solvated, i.e. melt‐crystallization‐type, polymer crystals. Unlike non‐solvated polymer crystals, for which the chain conformation is stabilized by its incorporation into a crystalline lattice, the β‐phase conformation is stabilized by complexation with solvent molecules and, therefore, its formation does not require specific inter‐chain interactions. The presented results clarify the fundamental differences between the β‐phase and other conformational/crystalline forms of polyfluorenes. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1492–1506 PMID:27546983

  13. "Long-distance" H/D isotopic self-organization phenomena in scope of the infrared spectra of hydrogen-bonded terephthalic and phthalic acid crystals.

    PubMed

    Flakus, Henryk T; Hachuła, Barbara; Hołaj-Krzak, Jakub T; Al-Agel, Faisal A; Rekik, Najeh

    2017-02-15

    This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h6-TAC isotopomer. In the case of the d4-TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h6 and d4, appeared much more susceptible for deuteration. A theoretical model was elaborated describing "long-distance" dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH)2 cycles. This leads to an additional stabilization of h6-TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric CH bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π-electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The "long-distance" dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules.

  14. "Long-distance" H/D isotopic self-organization phenomena in scope of the infrared spectra of hydrogen-bonded terephthalic and phthalic acid crystals

    NASA Astrophysics Data System (ADS)

    Flakus, Henryk T.; Hachuła, Barbara.; Hołaj-Krzak, Jakub T.; Al-Agel, Faisal A.; Rekik, Najeh

    2017-02-01

    This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h6-TAC isotopomer. In the case of the d4-TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h6 and d4, appeared much more susceptible for deuteration. A theoretical model was elaborated describing "long-distance" dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH)2 cycles. This leads to an additional stabilization of h6-TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric Csbnd H bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π-electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The "long-distance" dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules.

  15. Solution-Crystallization and Related Phenomena in 9,9-Dialkyl-Fluorene Polymers. I. Crystalline Polymer-Solvent Compound Formation for Poly(9,9-dioctylfluorene)

    PubMed Central

    Perevedentsev, Aleksandr; Stavrinou, Paul N; Bradley, Donal D C; Smith, Paul

    2015-01-01

    Polymer-solvent compound formation, occurring via co-crystallization of polymer chains and selected small-molecular species, is demonstrated for the conjugated polymer poly(9,9-dioctylfluorene) (PFO) and a range of organic solvents. The resulting crystallization and gelation processes in PFO solutions are studied by differential scanning calorimetry, with X-ray diffraction providing additional information on the resulting microstructure. It is shown that PFO-solvent compounds comprise an ultra-regular molecular-level arrangement of the semiconducting polymer host and small-molecular solvent guest. Crystals form following adoption of the planar-zigzag β-phase chain conformation, which, due to its geometry, creates periodic cavities that accommodate the ordered inclusion of solvent molecules of matching volume. The findings are formalized in terms of nonequilibrium temperature–composition phase diagrams. The potential applications of these compounds and the new functionalities that they might enable are also discussed. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1481–1491 PMID:26435576

  16. Depth-dependent ordering, two-length-scale phenomena, and crossover behavior in a crystal featuring a skin layer with defects

    SciTech Connect

    Del Genio, Charo I.; Bassler, Kevin E.; Korzhenevskii, Alexander L.; Barabash, Rozaliya; Trenkler, PhD Johann; Reiter, George; Moss, Simon

    2010-01-01

    Structural defects in a crystal are responsible for the ''two-length-scale'' behavior in which a sharp central peak is superimposed over a broad peak in critical diffuse x-ray scattering. We have previously measured the scaling behavior of the central peak by scattering from a near-surface region of a V{sub 2}H crystal, which has a first-order transition in the bulk. As the temperature is lowered toward the critical temperature, a crossover in critical behavior is seen, with the temperature range nearest to the critical point being characterized by mean-field exponents. Near the transition, a small two-phase coexistence region is observed. The values of transition and crossover temperatures decay with depth. An explanation of these experimental results is here proposed by means of a theory in which edge dislocations in the near-surface region occur in walls oriented in the two directions normal to the surface. The strain caused by the dislocation lines causes the ordering in the crystal to occur as growth of roughly cylindrically shaped regions. After the regions have reached a certain size, the crossover in the critical behavior occurs, and mean-field behavior prevails. At a still lower temperature, the rest of the material between the cylindrical regions orders via a weak first-order transition.

  17. Solution-Crystallization and Related Phenomena in 9,9-Dialkyl-Fluorene Polymers. I. Crystalline Polymer-Solvent Compound Formation for Poly(9,9-dioctylfluorene).

    PubMed

    Perevedentsev, Aleksandr; Stavrinou, Paul N; Bradley, Donal D C; Smith, Paul

    2015-11-01

    Polymer-solvent compound formation, occurring via co-crystallization of polymer chains and selected small-molecular species, is demonstrated for the conjugated polymer poly(9,9-dioctylfluorene) (PFO) and a range of organic solvents. The resulting crystallization and gelation processes in PFO solutions are studied by differential scanning calorimetry, with X-ray diffraction providing additional information on the resulting microstructure. It is shown that PFO-solvent compounds comprise an ultra-regular molecular-level arrangement of the semiconducting polymer host and small-molecular solvent guest. Crystals form following adoption of the planar-zigzag β-phase chain conformation, which, due to its geometry, creates periodic cavities that accommodate the ordered inclusion of solvent molecules of matching volume. The findings are formalized in terms of nonequilibrium temperature-composition phase diagrams. The potential applications of these compounds and the new functionalities that they might enable are also discussed. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1481-1491.

  18. Novel Colloidal and Dynamic Interfacial Phenomena in Liquid Crystalline Systems

    DTIC Science & Technology

    2014-09-13

    investigation supported by this grant moved beyond past studies of interfacial and colloidal phenomena involving isotropic liquids to explore and understand a...2010 20-May-2014 Approved for Public Release; Distribution Unlimited Final Report: Novel Colloidal and Dynamic Interfacial Phenomena in Liquid...Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 liquid crystals, interfacial phenomena, colloids , amphiphiles

  19. Transport Phenomena and Materials Processing

    NASA Astrophysics Data System (ADS)

    Kou, Sindo

    1996-10-01

    An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer

  20. Solid-state flow, mechanical alloying, and melt-related phenomena for [001] single-crystal tungsten ballistic rod penetrators interacting with steel targets

    NASA Astrophysics Data System (ADS)

    Pizana, Carlos

    This research program consists of a detailed microstructural investigation of in-target, single-crystal [001], clad (with Inconel 718) and unclad, W long-rod, ballistic penetrators. The rods were shot into rolled homogeneous armor (RHA) steel targets approximately 76 mm in thickness at impact velocities ranging from 1100 m/s to 1350 m/s. A comprehensive microstructural overview of the penetration process was obtained from this investigation. Solid-state flow/erosion, solid-state target/rod mixing as well as influencing factors such as strain rate, penetration performance, cladding interference and the interaction between target and projectile were emphasized. Some of the microstructural features observed, including deformation twins, cleaving, adiabatic shear bands and DRX support an overall solid-state penetration process. Furthermore they provide for a unifying perspective for the applicability of the hydrodynamic paradigm (DOP ≈ l∘rp/rt ) and earlier mechanistic erosion approaches. DRX and grain growth within adiabatic shear bands observed at specific high strain/strain-rate zones within the rods suggest that the projectile erodes by means of these microstructures in a solid-state form. This erosion process contributes to the performance of the rod by either allowing optimum flow of rod material which would increase penetration depth, or by maximizing rod material consumption which would reduce it. Since flow and/or erosion are also necessary in the target for perforation to occur, it is not surprising that the erosion process in the target was observed to mirror the one in the projectile. That is both target and projectile developed erosion zones with DRX facilitating the extreme deformation via dense overlapping shear band formation. Mechanical alloying and/or mixing of the target (steel) and rod (W, or W-Inconel 718) was also observed and investigated. Selective etching techniques as well as energy-dispersive x-ray mapping revealed unambiguous evidence of

  1. Molecular model for chirality phenomena.

    PubMed

    Latinwo, Folarin; Stillinger, Frank H; Debenedetti, Pablo G

    2016-10-21

    Chirality is a hallmark feature for molecular recognition in biology and chemical physics. We present a three-dimensional continuum model for studying chirality phenomena in condensed phases using molecular simulations. Our model system is based upon a simple four-site molecule and incorporates non-trivial kinetic behavior, including the ability to switch chirality or racemize, as well as thermodynamics arising from an energetic preference for specific chiral interactions. In particular, we introduce a chiral renormalization parameter that can locally favor either homochiral or heterochiral configurations. Using this model, we explore a range of chirality-specific phenomena, including the kinetics of chiral inversion, the mechanism of spontaneous chiral symmetry breaking in the liquid, chirally driven liquid-liquid phase separation, and chiral crystal structures.

  2. First principles study of the diffusional phenomena across the clean and Re-doped γ-Ni/γ’-Ni3Al interface of Ni-based single crystal superalloy

    NASA Astrophysics Data System (ADS)

    Min, Sun; Chong-Yu, Wang

    2016-06-01

    Density functional theory calculations in conjunction with the climbing images nudged elastic band method are conducted to study the diffusion phenomena of the Ni-based single crystal superalloys. We focus our attention on the diffusion processes of the Ni and Al atoms in the γ and γ’ phases along the direction perpendicular to the interface. The diffusion mechanisms and the expressions of the diffusion coefficients are presented. The vacancy formation energies, the migration energies, and the activation energies for the diffusing Ni and Al atoms are estimated, and these quantities display the expected and clear transition zones in the vicinity of the interface of about 3-7 (002) layers. The local density-of-states profiles of atoms in each (002) layer in the γ and γ’ phases and the partial density-of-states curves of Re and some of its nearest-neighbor atoms are also presented to explore the electronic effect of the diffusion behavior. Project supported by National Basic Research Program of China (Grant No. 2011CB606402) and the National Natural Science Foundation of China (Grant No. 51071091).

  3. Virtual Crystallizer

    SciTech Connect

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  4. Coupled Phenomena in Chemistry.

    ERIC Educational Resources Information Center

    Matsubara, Akira; Nomura, Kazuo

    1979-01-01

    Various phenomena in chemistry and biology can be understood through Gibbs energy utilization. Some common phenomena in chemistry are explained including neutralization, hydrolysis, oxidation and reaction, simultaneous dissociation equilibrium of two weak acids, and common ion effect on solubility. (Author/SA)

  5. Properties and Crystallization Phenomena in Li2Si2O5–Ca5(PO4)3F and Li2Si2O5–Sr5(PO4)3F Glass–Ceramics Via Twofold Internal Crystallization

    PubMed Central

    Rampf, Markus; Dittmer, Marc; Ritzberger, Christian; Schweiger, Marcel; Höland, Wolfram

    2015-01-01

    The combination of specific mechanical, esthetic, and chemical properties is decisive for the application of materials in prosthodontics. Controlled twofold crystallization provides a powerful tool to produce special property combinations for glass–ceramic materials. The present study outlines the potential of precipitating Ca5(PO4)3F as well as Sr5(PO4)3F as minor crystal phases in Li2Si2O5 glass–ceramics. Base glasses with different contents of CaO/SrO, P2O5, and F− were prepared within the glasses of the SiO2–Li2O–K2O–CaO/SrO–Al2O3–P2O5–F system. Preliminary studies of nucleation by means of XRD and scanning electron microscopy (SEM) of the nucleated base glasses revealed X-ray amorphous phase separation phenomena. Qualitative and quantitative crystal phase analyses after crystallization were conducted using XRD in combination with Rietveld refinement. As a main result, a direct proportional relationship between the content of apatite-forming components in the base glasses and the content of apatite in the glass–ceramics was established. The microstructures of the glass–ceramics were investigated using SEM. Microstructural and mechanical properties were found to be dominated by Li2Si2O5 crystals and quite independent of the content of the apatite present in the glass–ceramics. Biaxial strengths of up to 540 MPa were detected. Ca5(PO4)3F and Sr5(PO4)3F influence the translucency of the glass–ceramics and, hence, help to precisely tailor the properties of Li2Si2O5 glass–ceramics. The authors conclude that the twofold crystallization of Li2Si2O5–Ca5(PO4)3F or Li2Si2O5–Sr5(PO4)3F glass–ceramics involves independent solid-state reactions, which can be controlled via the chemical composition of the base glasses. The influence of the minor apatite phase on the optical properties helps to achieve new combinations of features of the glass–ceramics and, hence, displays new potential for dental applications. PMID:26389112

  6. Ion exchange phenomena

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  7. Imaging of snapping phenomena

    PubMed Central

    Guillin, R; Marchand, A J; Roux, A; Niederberger, E; Duvauferrier, R

    2012-01-01

    Snapping phenomena result from the sudden impingement between anatomical and/or heterotopical structures with subsequent abrupt movement and noise. Snaps are variously perceived by patients, from mild discomfort to significant pain requiring surgical management. Identifying the precise cause of snaps may be challenging when no abnormality is encountered on routinely performed static examinations. In this regard, dynamic imaging techniques have been developed over time, with various degrees of success. This review encompasses the main features of each imaging technique and proposes an overview of the main snapping phenomena in the musculoskeletal system. PMID:22744321

  8. Frost phenomena on Mars.

    PubMed

    Anderson, D M; Gaffney, E S; Low, P F

    1967-01-20

    The hypothesis that the Martian wave of darkening might be a frostheaving phenomenon has been examined. Consideration of the water-vapor sorption characteristics of a silicate mineral surface at temperatures below freezing leads to the conclusion that, without strongly deliquescent salts to attract and retain liquid water in the Martian soil, frost-heaving phenomena are not to be expected on Mars. On the other hand frost-heaving phenomena involving the freezing and thawing of ammonia may be common in the soils of Jupiter.

  9. Flow phenomena in turbomachines

    NASA Astrophysics Data System (ADS)

    Creitzer, E. M.; Epstein, A. H.; Giles, M. B.; McCune, J. E.; Tan, C. S.

    1993-01-01

    This report describes work carried out at the Gas Turbine Laboratory at MIT during the period 10/20/89 - 10/19/92, as part of our multi-investigator effort on basic unsteady flow phenomena in turbomachines. Within the overall project four separate tasks are specified. These are, in brief: (1) The Influence of Inlet Temperature Nonuniformities on Turbine Heat Transfer and Dynamics; (2) Assessment of Unsteady Losses in Stator/ Rotor Interactions; (3) Unsteady Phenomena and Flowfield instabilities in Multistage Axial Compressors; (4) Vortex Wake-Compressor Blade Interaction in Cascades - A New Rapid Method for Unsteady Separation and Vorticity Flux Calculations.

  10. BECA (Bilingual Education Centro de Accion) Program Handbook for Student Teachers and Supervisory Personnel.

    ERIC Educational Resources Information Center

    Reyes, Maria; And Others

    This manual is a reference guide for both student teachers and supervisory personnel involved with the Texas Woman's University Bilingual Education "Centro de Accion" (BECA) Program. The BECA program includes the following components in addition to the fulltime BECA undergraduate program: para-professional training program, graduate…

  11. Quantum phenomena in superconductors

    SciTech Connect

    Clarke, J.

    1987-08-01

    This paper contains remarks by the author on aspects of macroscopic quantum phenomena in superconductors. Some topics discussed are: Superconducting low-inductance undulatory galvanometer (SLUGS), charge imbalance, cylindrical dc superconducting quantum interference device (SQUIDS), Geophysics, noise theory, magnetic resonance with SQUIDS, and macroscopic quantum tunneling. 23 refs., 4 figs. (LSP)

  12. Fundamentals of Electromagnetic Phenomena

    NASA Astrophysics Data System (ADS)

    Lorrain, Paul; Corson, Dale R.; Lorrain, Francois

    Based on the classic Electromagnetic Fields and Waves by the same authors, Fundamentals of Electromagnetic Phenomena capitalizes on the older text's traditional strengths--solid physics, inventive problems, and an experimental approach--while offering a briefer, more accessible introduction to the basic principles of electromagnetism.

  13. Investigating Dissolution and Precipitation Phenomena with a Smartphone Microscope

    SciTech Connect

    Lumetta, Gregg J.; Arcia, Edgar

    2016-10-11

    A novel smartphone microscope can be used to observe the dissolution and crystallization of sodium chloride at a microscopic level. Observation of these seemingly simple phenomena through the microscope at 100× magnification can actually reveal some surprising behavior. These experiments offer the opportunity to discuss some basic concepts such as how the morphological features of the crystals dictates how the dissolution process proceeds, and how materials can be purified by re-crystallization techniques.

  14. Membrane Transport Phenomena (MTP)

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.

    1997-01-01

    The third semi-annual period of the MTP project has been involved with performing experiments using the Membrane Transport Apparatus (MTA), development of analysis techniques for the experiment results, analytical modeling of the osmotic transport phenomena, and completion of a DC-9 microgravity flight to test candidate fluid cell geometries. Preparations were also made for the MTP Science Concept Review (SCR), held on 13 June 1997 at Lockheed Martin Astronautics in Denver. These activities are detailed in the report.

  15. Lunar transient phenomena

    NASA Astrophysics Data System (ADS)

    Cameron, W. S.

    1991-03-01

    Lunar transient phenomena (LTP) sightings are classified into five categories: brightenings, darkenings, reddish colorations, bluish colorations, and obscurations. There is evidence that the remaining LTP's are of lunar origin. A substantial number of sightings are independently confirmed. They have been recorded on film and spectrograms, as well as with photoelectric photometers and polarization equipment. It suggested that the LTP's may be gentle outgassings of less-than-volcanic proportions.

  16. Paramutation phenomena in plants.

    PubMed

    Pilu, Roberto

    2015-08-01

    Paramutation is a particular epigenetic phenomenon discovered in Zea mays by Alexander Brink in the 1950s, and then also found in other plants and animals. Brink coined the term paramutation (from the Greek syllable "para" meaning beside, near, beyond, aside) in 1958, with the aim to differentiate paramutation from mutation. The peculiarity of paramutation with respect to other gene silencing phenomena consists in the ability of the silenced allele (named paramutagenic) to silence the other allele (paramutable) present in trans. The newly silenced (paramutated) allele remains stable in the next generations even after segregation from the paramutagenic allele and acquires paramutagenic ability itself. The inheritance behaviour of these epialleles permits a fast diffusion of a particular gene expression level/phenotype in a population even in the absence of other evolutionary influences, thus breaking the Hardy-Weinberg law. As with other gene silencing phenomena such as quelling in the fungus Neurospora crassa, transvection in Drosophila, co-suppression and virus-induced gene silencing (VIGS) described in transgenic plants and RNA interference (RNAi) in the nematode Caenorhabditis elegans, paramutation occurs without changes in the DNA sequence. So far the molecular basis of paramutation remains not fully understood, although many studies point to the involvement of RNA causing changes in DNA methylation and chromatin structure of the silenced genes. In this review I summarize all paramutation phenomena described in plants, focusing on the similarities and differences between them.

  17. [Lateralization phenomena and headache].

    PubMed

    Nattero, G; Savi, L

    1984-09-08

    Ipsilateral carotid and vertebral vasomotor phenomena are marked components of a unilateral cluster headache crisis. Investigation of lateralisation at the height of a crisis has shown that Doppler findings supplement Heick's observation of the reversible opening of both intra and extracranial arteriovenous shunts. This observation is in line with personal thermographic evidence and that of Lance indicating local hypothermia, and with Wolff's demonstration of dilatation and congestion associated with the superficial temporal artery. Personal dynamographic findings now point to a local extra-intracranial artery pressure gradient as the cause of the peripheral component of lateralisation in cluster headache.

  18. Wolf-Rayet phenomena

    NASA Technical Reports Server (NTRS)

    Conti, P. S.

    1982-01-01

    The properties of stars showing Wolf-Rayet phenomena are outlined along with the direction of future work. Emphasis is placed on the characteristics of W-R spectra. Specifically the following topics are covered: the absolute visual magnitudes; the heterogeneity of WN spectra; the existence of transition type spectra and compositions the mass loss rates; and the existence of very luminous and possibly very massive W-R stars. Also, a brief overview of current understanding of the theoretical aspects of stellar evolution and stellar winds and the various scenarios that have been proposed to understand W-R spectra are included.

  19. Breakdown phenomena in rf windows

    SciTech Connect

    Saito, Y.

    1995-07-05

    The multipactor and flashover phenomena of alumina rf windows used in high-power klystrons have been investigated. Multipactoring due to the high yield of secondary electron emission takes place during rf operation. A spectrum analysis of the luminescence due to multipactoring shows that multipactor electron bombardment causes an F-center of alumina, thus leading to surface melting. From the results of a high-power examination of rf windows with several kinds of alumina ceramics, it was found that an alumina material with a crystallized grain-boundary and without any voids between the boundaries, thus having a low loss-tangent value, is not liable to F-centers, even under multipactoring. Flashovers in a tree-like pattern of alumina luminescence occasionally take place on a TiN-coated surface. From the results of surface-charging measurements and high-power examinations of annealed alumina disks, the flashover phenomenon is considered to be an avalanche of electrons which have been trapped in mechanically introduced defects. The effectivenesses of multipactor-suppressing coatings and of a field-reduced window structure were also examined. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  20. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  1. Weld pool phenomena

    SciTech Connect

    David, S.A.; Vitek, J.M.; Zacharia, T.; DebRoy, T.

    1994-09-01

    During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

  2. Thermal Wave Phenomena

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This map from the MGS Horizon Sensor Assembly (HORSE) shows middle atmospheric temperatures near the 1 mbar level of Mars between Ls 170 to 175 (approx. July 14 - 23, 1999). Local Mars times between 1:30 and 4:30 AM are included. Infrared radiation measured by the Mars Horizon Sensor Assembly was used to make the map. That device continuously views the 'limb' of Mars in four directions, to help orient the spacecraft instruments to the nadir: straight down.

    The map shows thermal wave phenomena that are caused by the large topographic variety of Mars' surface, as well the latitudinally symmetric behavior expected at this time of year near the equinox.

  3. Generalized Bloch theorem and chiral transport phenomena

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naoki

    2015-10-01

    Bloch theorem states the impossibility of persistent electric currents in the ground state of nonrelativistic fermion systems. We extend this theorem to generic systems based on the gauged particle number symmetry and study its consequences on the example of chiral transport phenomena. We show that the chiral magnetic effect can be understood as a generalization of the Bloch theorem to a nonequilibrium steady state, similarly to the integer quantum Hall effect. On the other hand, persistent axial currents are not prohibited by the Bloch theorem and they can be regarded as Pauli paramagnetism of relativistic matter. An application of the generalized Bloch theorem to quantum time crystals is also discussed.

  4. ON DETECTING TRANSIENT PHENOMENA

    SciTech Connect

    Belanger, G.

    2013-08-10

    Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximize the sensitivity of the method used to identify such events. In this article, we present a general procedure based on the use of the likelihood function for identifying transients which is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method makes use of all the information that is available in the data throughout the statistical decision-making process, and is suitable for a wide range of applications. Here we consider those most common in astrophysics, which involve searching for transient sources, events or features in images, time series, energy spectra, and power spectra, and demonstrate the use of the method in the case of a weak X-ray flare in a time series and a short-lived quasi-periodic oscillation in a power spectrum. We derive a fit statistic that is ideal for fitting arbitrarily shaped models to a power density distribution, which is of general interest in all applications involving periodogram analysis.

  5. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  6. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  7. NASA research Program: The roles of fluid motion and other transport phenomena in the morphology of materials

    NASA Technical Reports Server (NTRS)

    Saville, D. A.

    1988-01-01

    The influence of transport phenomena on the morphology of crystalline materials was investigated. Two problems were studied: the effects of convection on the crystallization of pure materials, and the crystallization of proteins from solution.

  8. Hysteresis phenomena in hydraulic measurement

    NASA Astrophysics Data System (ADS)

    Ran, H. J.; Luo, X. W.; Chen, Y. L.; Xu, H. Y.; Farhat, M.

    2012-11-01

    Hysteresis phenomena demonstrate the lag between the generation and the removal of some physical phenomena. This paper studies the hysteresis phenomena of the head-drop in a scaled model pump turbine using experiment test and CFD methods. These lag is induced by complicated flow patterns, which influenced the reliability of rotating machine. Keeping the same measurement procedure is concluded for the hydraulic machine measurement.

  9. Hypervelocity impact phenomena

    NASA Astrophysics Data System (ADS)

    Chhabildas, L. C.

    There is a need to determine the equations of state of materials in regimes of extreme high pressures, temperatures, and strain rates that are not attainable on current two-stage light-gas guns. Understanding high-pressure material behavior is crucial to address the physical processes associated with a variety of hypervelocity impact events related to space sciences: orbital-debris impact, debris-shield designs, high-speed plasma propagation, and impact lethality applications. At very high impact velocities material properties will be dominated by phase-changes, such as melting or vaporization, which cannot be achieved at lower impact velocities. Development of well-controlled and repeatable hypervelocity launch capabilities is the first step necessary to improve our understanding of material behavior at extreme pressures and temperatures not currently available using conventional two-stage light-gas gun techniques. Techniques that have been used to extend both the launch capabilities of a two-stage light-gas gun to 16 km/s, and their use to determine the material properties at pressures and temperature states higher than those ever obtained in the laboratory, are summarized. The newly developed hypervelocity launcher (HVL) can launch intact (macroscopic dimensions) plates to 16 km/s. Time-resolved interferometric techniques have been used to determine shock-loading/release characteristics of materials impacted by such fliers as well as shock-induced vaporization phenomena in fully vaporized states. High-speed photography or radiography has been used to evaluate the debris propagation characteristics resulting from disc impact of thin bumper sheets at hypervelocities in excess of 10 km/s using the HVL. Examples of these experiments are provided.

  10. Hypervelocity impact phenomena

    SciTech Connect

    Chhabildas, L.C.

    1995-07-01

    There is a need to determine the equations of state of materials in regimes of extreme high pressures, temperatures and strain rates that are not attainable on current two-stage light-gas guns. Understanding high-pressure material behavior is crucial to address the physical processes associated with a variety of hypervelocity impact events related to space sciences-orbital-debris impact, debris-shield designs, high-speed plasma propagation, and impact lethality applications. At very high impact velocities material properties will be dominated by phase-changes, such as melting or vaporization, which cannot be achieved at lower impact velocities. Development of well-controlled and repeatable hypervelocity launch capabilities is the first step necessary to improve our understanding of material behavior at extreme pressures and temperatures not currently available using conventional two-stage light-gas gun techniques. In this paper, techniques that have been used to extend both the launch capabilities of a two-stage light gas gun to 16 km/s, and their use to determine the material properties at pressures and temperature states higher than those ever obtained in the laboratory are summarized. The newly developed hypervelocity launcher (HVL) can launch intact (macroscopic dimensions) plates to 16 km/s. Time-resolved interferometric techniques have been used to determine shock-loading/release characteristics of materials impacted by such fliers as well as shock-induced vaporization phenomena in fully vaporized states. High-speed photography or radiography has been used to evaluate the debris propagation characteristics resulting from disc impact of thin bumper sheets at hypervelocities in excess of 10 km/s using the HVL. Examples of these experiments are provided in this paper.

  11. Teaching Optical Phenomena with Tracker

    ERIC Educational Resources Information Center

    Rodrigues, M.; Carvalho, P. Simeão

    2014-01-01

    Since the invention and dissemination of domestic laser pointers, observing optical phenomena is a relatively easy task. Any student can buy a laser and experience at home, in a qualitative way, the reflection, refraction and even diffraction phenomena of light. However, quantitative experiments need instruments of high precision that have a…

  12. Wave phenomena in sunspots

    NASA Astrophysics Data System (ADS)

    Löhner-Böttcher, Johannes

    2016-03-01

    Context: The dynamic atmosphere of the Sun exhibits a wealth of magnetohydrodynamic (MHD) waves. In the presence of strong magnetic fields, most spectacular and powerful waves evolve in the sunspot atmosphere. Allover the sunspot area, continuously propagating waves generate strong oscillations in spectral intensity and velocity. The most prominent and fascinating phenomena are the 'umbral flashes' and 'running penumbral waves' as seen in the sunspot chromosphere. Their nature and relation have been under intense discussion in the last decades. Aims: Waves are suggested to propagate upward along the magnetic field lines of sunspots. An observational study is performed to prove or disprove the field-guided nature and coupling of the prevalent umbral and penumbral waves. Comprehensive spectroscopic observations at high resolution shall provide new insights into the wave characteristics and distribution across the sunspot atmosphere. Methods: Two prime sunspot observations were carried out with the Dunn Solar Telescope at the National Solar Observatory in New Mexico and with the Vacuum Tower Telescope at the Teide Observatory on Tenerife. The two-dimensional spectroscopic observations were performed with the interferometric spectrometers IBIS and TESOS. Multiple spectral lines are scanned co-temporally to sample the dynamics at the photospheric and chromospheric layers. The time series (1 - 2.5 h) taken at high spatial and temporal resolution are analyzed according to their evolution in spectral intensities and Doppler velocities. A wavelet analysis was used to obtain the wave power and dominating wave periods. A reconstruction of the magnetic field inclination based on sunspot oscillations was developed. Results and conclusions: Sunspot oscillations occur continuously in spectral intensity and velocity. The obtained wave characteristics of umbral flashes and running penumbral waves strongly support the scenario of slow-mode magnetoacoustic wave propagation along the

  13. Misconceptions of Emergent Semiconductor Phenomena

    NASA Astrophysics Data System (ADS)

    Nelson, Katherine G.

    The semiconductor field of Photovoltaics (PV) has experienced tremendous growth, requiring curricula to consider ways to promote student success. One major barrier to success students may face when learning PV is the development of misconceptions. The purpose of this work was to determine the presence and prevalence of misconceptions students may have for three PV semiconductor phenomena; Diffusion, Drift and Excitation. These phenomena are emergent, a class of phenomena that have certain characteristics. In emergent phenomena, the individual entities in the phenomena interact and aggregate to form a self-organizing pattern that can be observed at a higher level. Learners develop a different type of misconception for these phenomena, an emergent misconception. Participants (N=41) completed a written protocol. The pilot study utilized half of these protocols (n = 20) to determine the presence of both general and emergent misconceptions for the three phenomena. Once the presence of both general and emergent misconceptions was confirmed, all protocols (N=41) were analyzed to determine the presence and prevalence of general and emergent misconceptions, and to note any relationships among these misconceptions (full study). Through written protocol analysis of participants' responses, numerous codes emerged from the data for both general and emergent misconceptions. General and emergent misconceptions were found in 80% and 55% of participants' responses, respectively. General misconceptions indicated limited understandings of chemical bonding, electricity and magnetism, energy, and the nature of science. Participants also described the phenomena using teleological, predictable, and causal traits, indicating participants had misconceptions regarding the emergent aspects of the phenomena. For both general and emergent misconceptions, relationships were observed between similar misconceptions within and across the three phenomena, and differences in misconceptions were

  14. Instability phenomena in plasticity: Modelling and computation

    NASA Astrophysics Data System (ADS)

    Stein, E.; Steinmann, P.; Miehe, C.

    1995-12-01

    We presented aspects and results related to the broad field of strain localization with special focus on large strain elastoplastic response. Therefore, we first re-examined issues related to the classification of discontinuities and the classical description of localization with a particular emphasis on an Eulerian geometric representation. We touched the problem of mesh objectivity and discussed results of a particular regularization method, namely the micropolar approach. Generally, regularization has to preserve ellipticity and to reflect the underlying physics. For example ductile materials have to be modelled including viscous effects whereas geomaterials are adequately described by the micropolar approach. Then we considered localization phenomena within solids undergoing large strain elastoplastic deformations. Here, we documented the influence of isotropic damage on the failure analysis. Next, the interesting influence of an orthotropic yield condition on the spatial orientation of localized zones has been studied. Finally, we investigated the localization condition for an algorithmic model of finite strain single crystal plasticity.

  15. Physical phenomena and the microgravity response

    NASA Technical Reports Server (NTRS)

    Todd, Paul

    1989-01-01

    The living biological cell is not a sack of Newtonian fluid containing systems of chemical reactions at equilibrium. It is a kinetically driven system, not a thermodynamically driven system. While the cell as a whole might be considered isothermal, at the scale of individual macromolecular events there is heat generated, and presumably sharp thermal gradients exist at the submicron level. Basic physical phenomena to be considered when exploring the cell's response to inertial acceleration include particle sedimentation, solutal convection, motility electrokinetics, cytoskeletal work, and hydrostatic pressure. Protein crystal growth experiments, for example, illustrate the profound effects of convection currents on macromolecular assembly. Reaction kinetics in the cell vary all the way from diffusion-limited to life-time limited. Transport processes vary from free diffusion, to facilitated and active transmembrane transport, to contractile-protein-driven motility, to crystalline immobilization. At least four physical states of matter exist in the cell: aqueous, non-aqueous, immiscible-aqueous, and solid. Levels of order vary from crystalline to free solution. The relative volumes of these states profoundly influence the cell's response to inertial acceleration. Such subcellular phenomena as stretch-receptor activation, microtubule re-assembly, synaptic junction formation, chemotactic receptor activation, and statolith sedimentation were studied recently with respect to both their basic mechanisms and their responsiveness to inertial acceleration. From such studies a widespread role of cytoskeletal organization is becoming apparent.

  16. Teaching optical phenomena with Tracker

    NASA Astrophysics Data System (ADS)

    Rodrigues, M.; Simeão Carvalho, P.

    2014-11-01

    Since the invention and dissemination of domestic laser pointers, observing optical phenomena is a relatively easy task. Any student can buy a laser and experience at home, in a qualitative way, the reflection, refraction and even diffraction phenomena of light. However, quantitative experiments need instruments of high precision that have a relatively complex setup. Fortunately, nowadays it is possible to analyse optical phenomena in a simple and quantitative way using the freeware video analysis software ‘Tracker’. In this paper, we show the advantages of video-based experimental activities for teaching concepts in optics. We intend to show: (a) how easy the study of such phenomena can be, even at home, because only simple materials are needed, and Tracker provides the necessary measuring instruments; and (b) how we can use Tracker to improve students’ understanding of some optical concepts. We give examples using video modelling to study the laws of reflection, Snell’s laws, focal distances in lenses and mirrors, and diffraction phenomena, which we hope will motivate teachers to implement it in their own classes and schools.

  17. Abnormal pressures as hydrodynamic phenomena

    USGS Publications Warehouse

    Neuzil, C.E.

    1995-01-01

    So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

  18. Undergraduates' understanding of cardiovascular phenomena.

    PubMed

    Michael, Joel A; Wenderoth, Mary Pat; Modell, Harold I; Cliff, William; Horwitz, Barbara; McHale, Philip; Richardson, Daniel; Silverthorn, Dee; Williams, Stephen; Whitescarver, Shirley

    2002-12-01

    Undergraduates students in 12 courses at 8 different institutions were surveyed to determine the prevalence of 13 different misconceptions (conceptual difficulties) about cardiovascular function. The prevalence of these misconceptions ranged from 20 to 81% and, for each misconception, was consistent across the different student populations. We also obtained explanations for the students' answers either as free responses or with follow-up multiple-choice questions. These results suggest that students have a number of underlying conceptual difficulties about cardiovascular phenomena. One possible source of some misconceptions is the students' inability to apply simple general models to specific cardiovascular phenomena. Some implications of these results for teachers of physiology are discussed.

  19. Current program to investigate phenomena in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Oran, William A.

    1986-01-01

    Current NASA Microgravity Science and Applications Division Shuttle and terrestrial experiments to acquire basic data for space-based materials processing activities are summarized. The research is carried out to increase the understanding and to improve ground-based and space-based processing, to enhance the understanding of basic physical phenomena, and to characterize the forces which effect low-gravity processing. The main areas of research are crystal growth, metallic alloy solidification, bioseparation processes, blood rheology, containerless processing, and studies of combustion processes, chemical and transport phenomena, cloud microphysics and fluid behavior and surface phenomena in microgravity. Specific experiments, which exemplify the research goals and were performed on KC-135 flights along Keplerian trajectories and on Shuttle missions, are described.

  20. Quantum Phenomena Observed Using Electrons

    SciTech Connect

    Tonomura, Akira

    2011-05-06

    Electron phase microscopy based on the Aharonov-Bohm (AB) effect principle has been used to illuminate fundamental phenomena concerning magnetism and superconductivity by visualizing quantitative magnetic lines of force. This paper deals with confirmation experiments on the AB effect, the magnetization process of tiny magnetic heads for perpendicular recording, and vortex behaviors in high-Tc superconductors.

  1. Discovery potential for new phenomena

    SciTech Connect

    Godfrey, S.; Hewett, J.L.; Price, L.E.

    1997-03-01

    The authors examine the ability of future facilities to discover and interpret non-supersymmetric new phenomena. The authors first explore explicit manifestations of new physics, including extended gauge sectors, leptoquarks, exotic fermions, and technicolor models. They then take a more general approach where new physics only reveals itself through the existence of effective interactions at lower energy scales.

  2. Visualizing Chemical Phenomena in Microdroplets

    ERIC Educational Resources Information Center

    Lee, Sunghee; Wiener, Joseph

    2011-01-01

    Phenomena that occur in microdroplets are described to the undergraduate chemistry community. Droplets having a diameter in the micrometer range can have unique and interesting properties, which arise because of their small size and, especially, their high surface area-to-volume ratio. Students are generally unfamiliar with the characteristics of…

  3. PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena

    NASA Astrophysics Data System (ADS)

    Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo

    2010-10-01

    Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 (http://needs-conferences.net/2009/). The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed

  4. Single event phenomena: A summary

    NASA Astrophysics Data System (ADS)

    Price, W. E.; Coss, J. R.

    1989-04-01

    Single event phenomena (SEP) are effects resulting from a single particle inducing a significant response in an integrated circuit. SEP are of greatest concern to spacecraft designers but are becoming of concern to avionics and large earth-bound electronic systems due to the continual reduction in size (which increases SEP sensitivity) of circuit elements. The phenomena include soft error and multiple errors in memory cells or logic latches, latchup, MOSFET power device burnout, MNOS punch-through and transients. Cyclotron and Van de Graaff accelerators are used to produce heavy ions, protons and neutrons which induce SEP effects. Methods of testing are described. Solutions to SEP are varied, but include parts substitutions or redesign and software solutions which will be described.

  5. Statistical phenomena in particle beams

    SciTech Connect

    Bisognano, J.J.

    1984-09-01

    Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

  6. Thermodynamic constraints on fluctuation phenomena.

    PubMed

    Maroney, O J E

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  7. Thermodynamic constraints on fluctuation phenomena

    NASA Astrophysics Data System (ADS)

    Maroney, O. J. E.

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  8. New phenomena searches at CDF

    SciTech Connect

    Soha, Aron; /UC, Davis

    2006-04-01

    The authors report on recent results from the Collider Detector at Fermilab (CDF) experiment, which is accumulating data from proton-antiproton collisions with {radical}s = 1.96 TeV at Run II of the Fermilab Tevatron. The new phenomena being explored include Higgs, Supersymmetry, and large extra dimensions. They also present the latest results of searches for heavy objects, which would indicate physics beyond the Standard Model.

  9. Visualization of solidification front phenomena

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Smith, Guy A.

    1993-01-01

    Directional solidification experiments have been utilized throughout the Materials Processing in Space Program to provide an experimental platform which minimizes variables in solidification experiments. Because of the wide-spread use of this experimental technique in space-based research, it has become apparent that a better understanding of all the phenomena occurring during solidification can be better understood if direct visualization of the solidification interface were possible.

  10. Mathematical Modeling of Diverse Phenomena

    NASA Technical Reports Server (NTRS)

    Howard, J. C.

    1979-01-01

    Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

  11. Unsteady Aerodynamic Phenomena in Turbomachines

    DTIC Science & Technology

    1990-02-01

    The first part of a systematic variation of important parameters shows their influence on the aerodynamic forces and moments coefficients . 2-2...real physical phenomena. Besides, for reasons of stability it in necessary to introduce an additional damping coefficient , which depends on the... coefficients for the "Fourth Standard Configu- ration No. 4" /10/, using a mesh with 51 x 17 points (Fig. I). This grid represents a typical section of

  12. Correlated randomness and switching phenomena

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  13. Phenomena and Diosignes of Aratous

    NASA Astrophysics Data System (ADS)

    Avgoloupis, S. I.

    2013-01-01

    Aratous (305-240B.C.) was a singular intellectual, writer and poet which engage himself to compose a very interesting astronomical poet, using the "Dactylous sixstage' style, the formal style of the ancient Greek Epic poetry. This astronomic poem of Aratous "Phenomena and Diosignes" became very favorite reading during the Alexandrine, the Romman and the Byzandin eras as well and had received many praises from significant poets and particularly from Hipparchous and from Theonas from Alexandria, an astronomer of 4rth century A.C.(in Greeks)

  14. Functional theories of thermoelectric phenomena

    NASA Astrophysics Data System (ADS)

    Eich, F. G.; Di Ventra, M.; Vignale, G.

    2017-02-01

    We review the progress that has been recently made in the application of time-dependent density functional theory to thermoelectric phenomena. As the field is very young, we emphasize open problems and fundamental issues. We begin by introducing the formal structure of thermal density functional theory, a density functional theory with two basic variables—the density and the energy density—and two conjugate fields—the ordinary scalar potential and Luttinger’s thermomechanical potential. The static version of this theory is contrasted with the familiar finite-temperature density functional theory, in which only the density is a variable. We then proceed to constructing the full time-dependent non equilibrium theory, including the practically important Kohn-Sham equations that go with it. The theory is shown to recover standard results of the Landauer theory for thermal transport in the steady state, while showing greater flexibility by allowing a description of fast thermal response, temperature oscillations and related phenomena. Several results are presented here for the first time, i.e. the proof of invertibility of the thermal response function in the linear regime, the full expression of the thermal currents in the presence of Luttinger’s thermomechanical potential, an explicit prescription for the evaluation of the Kohn-Sham potentials in the adiabatic local density approximation, a detailed discussion of the leading dissipative corrections to the adiabatic local density approximation and the thermal corrections to the resistivity that follow from it.

  15. Critical phenomena on k -booklets

    NASA Astrophysics Data System (ADS)

    Grassberger, Peter

    2017-01-01

    We define a "k -booklet" to be a set of k semi-infinite planes with -∞ phenomena: self-avoiding random walks, the Ising model, and percolation. For k =2 , a booklet is equivalent to a single infinite lattice, and for k =1 to a semi-infinite lattice. In both these cases the systems show standard critical phenomena. This is not so for k ≥3 . Self-avoiding walks starting at y =0 show a first-order transition at a shifted critical point, with no power-behaved scaling laws. The Ising model and percolation show hybrid transitions, i.e., the scaling laws of the standard models coexist with discontinuities of the order parameter at y ≈0 , and the critical points are not shifted. In the case of the Ising model, ergodicity is already broken at T =Tc , and not only for T

  16. Uranium Pyrophoricity Phenomena and Prediction

    SciTech Connect

    DUNCAN, D.R.

    2000-04-20

    We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

  17. Natural phenomena hazards, Hanford Site, Washington

    SciTech Connect

    Conrads, T.J.

    1998-09-29

    This document presents the natural phenomena hazard loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, and supports development of double-shell tank systems specifications at the Hanford Site in south-central Washington State. The natural phenomena covered are seismic, flood, wind, volcanic ash, lightning, snow, temperature, solar radiation, suspended sediment, and relative humidity.

  18. Investigation of collective phenomena in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Ruhunusiri, Wellalage Don Suranga

    I study dusty plasma produced by electrostatically confining melamine formaldehyde microparticles in a radio-frequency glow discharge plasma. Dusty plasma is a mixture of particles of solid matter (dust), electrons, ions, and neutral gas atoms. The dust particles have a very high charge and a mass compared to the electrons and ions in the ambient plasma. As a consequence, a dusty plasma exhibits collective phenomena such as dust acoustic waves, crystallization, and melting. The discrete nature of dust particles gives rise to compressibility. In this thesis I report findings of four tasks that were performed to investigate dust acoustic waves, compressibility, and melting. First, the nonlinear phenomenon of synchronization was characterized experimentally for the dust acoustic wave propagating in a dust cloud with many layers. I find four synchronized states, with frequencies that are multiples of 1, 2, 3, and 1/2 of the driving frequency. Comparing to phenomena that are typical of the van der Pol paradigm, I find that synchronization of the dust acoustic wave exhibits the signature of the suppression mechanism but not that of the phaselocking mechanism. Additionally, I find that the synchronization of the dust acoustic wave exhibits three characteristics that differ from the van der Pol paradigm: a threshold amplitude that can be seen in the Arnold tongue diagram, a branching of the 1:1 harmonic tongue at its lower extremity, and a nonharmonic state. Second, to assess which physical processes are important for a dust acoustic instability, I derived dispersion relations that encompass more physical processes than commonly done. I investigated how various physical processes affect a dust acoustic wave by solving these dispersion relations using parameters from a typical dust acoustic wave experiment. I find that the growth rate diminishes for large ion currents. I also find that the compressibility, a measure of the coupling between the dust particles, have a strong

  19. Emergent Phenomena at Oxide Interfaces

    SciTech Connect

    Hwang, H.Y.

    2012-02-16

    Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burst of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the spin

  20. Earthquake prediction with electromagnetic phenomena

    SciTech Connect

    Hayakawa, Masashi

    2016-02-01

    Short-term earthquake (EQ) prediction is defined as prospective prediction with the time scale of about one week, which is considered to be one of the most important and urgent topics for the human beings. If this short-term prediction is realized, casualty will be drastically reduced. Unlike the conventional seismic measurement, we proposed the use of electromagnetic phenomena as precursors to EQs in the prediction, and an extensive amount of progress has been achieved in the field of seismo-electromagnetics during the last two decades. This paper deals with the review on this short-term EQ prediction, including the impossibility myth of EQs prediction by seismometers, the reason why we are interested in electromagnetics, the history of seismo-electromagnetics, the ionospheric perturbation as the most promising candidate of EQ prediction, then the future of EQ predictology from two standpoints of a practical science and a pure science, and finally a brief summary.

  1. Thermophysical parameters of the LBO crystal

    SciTech Connect

    Grechin, Sergei G; Zuev, A V; Fokin, A S; Kokh, Aleksandr E; Moiseev, N V; Popov, Petr A; Sidorov, Aleksei A

    2010-08-27

    The thermophysical parameters (linear thermal expansion coefficients, thermal conductivities, and heat capacity) of the lithium triborate (LBO) crystal are measured and compared with previously published data. (nonlinear-optics phenomena)

  2. Purcell effect and Lamb shift as interference phenomena

    PubMed Central

    Rybin, Mikhail V.; Mingaleev, Sergei F.; Limonov, Mikhail F.; Kivshar, Yuri S.

    2016-01-01

    The Purcell effect and Lamb shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference wave phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the Lamb shift can exceed 3 half-widths of the cavity spectral line. PMID:26860195

  3. Purcell effect and Lamb shift as interference phenomena.

    PubMed

    Rybin, Mikhail V; Mingaleev, Sergei F; Limonov, Mikhail F; Kivshar, Yuri S

    2016-02-10

    The Purcell effect and Lamb shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference wave phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the Lamb shift can exceed 3 half-widths of the cavity spectral line.

  4. Purcell effect and Lamb shift as interference phenomena

    NASA Astrophysics Data System (ADS)

    Rybin, Mikhail V.; Mingaleev, Sergei F.; Limonov, Mikhail F.; Kivshar, Yuri S.

    2016-02-01

    The Purcell effect and Lamb shift are two well-known physical phenomena which are usually discussed in the context of quantum electrodynamics, with the zero-point vibrations as a driving force of those effects in the quantum approach. Here we discuss the classical counterparts of these quantum effects in photonics, and explain their physics trough interference wave phenomena. As an example, we consider a waveguide in a planar photonic crystal with a side-coupled defect, and demonstrate a perfect agreement between the results obtained on the basis of quantum and classic approaches and reveal their link to the Fano resonance. We find that in such a waveguide-cavity geometry the Purcell effect can modify the lifetime by at least 25 times, and the Lamb shift can exceed 3 half-widths of the cavity spectral line.

  5. Turbulent phenomena in protein folding.

    PubMed

    Kalgin, Igor V; Chekmarev, Sergei F

    2011-01-01

    Protein folding and hydrodynamic turbulence are two long-standing challenges, in molecular biophysics and fluid dynamics, respectively. The theories of these phenomena have been developed independently and used different formalisms. Here we show that the protein folding flows can be surprisingly similar to turbulent fluid flows. Studying a benchmark model protein (an SH3 domain), we have found that the flows for the slow folding trajectories of the protein, in which a partly formed N- and C-terminal β sheet hinders the RT loop from attaching to the protein core, have many properties of turbulent flows of a fluid. The flows are analyzed in a three-dimensional (3D) space of collective variables, which are the numbers of native contacts between the terminal β strands, between the RT loop and the protein core, and the rest of the native contacts. We have found that the flows have fractal nature and are filled with 3D eddies; the latter contain strange attractors, at which the tracer flow paths behave as saddle trajectories. Two regions of the space increment have been observed, in which the flux variations are self-similar with the scaling exponent h=1/3, in surprising agreement with the Kolmogorov inertial range theory of turbulence. In one region, the cascade of protein rearrangements is directed from larger to smaller scales (net folding), and in the other, it is oppositely directed (net unfolding). Folding flows for the fast trajectories are essentially "laminar" and do not have the property of self-similarity. Based on the results of our study, we infer, and support this inference by simulations, that the origin of the similarity between the protein folding and turbulent motion of a fluid is in a cascade mechanism of structural transformations in the systems that underlies these phenomena.

  6. Crystal growth and crystallography

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    1998-01-01

    Selected topics that may be of interest for both crystal-structure and crystal-growth communities are overviewed. The growth of protein crystals, along with that of some other compounds, is one of the topics, and recent insights into related phenomena are considered as examples of applications of general principles. The relationship between crystal growth shape and structure is reviewed and an attempt to introduce semiquantitative characterization of binding for proteins is made. The concept of kinks for complex structures is briefly discussed. Even at sufficiently low supersaturations, the fluctuation of steps may not be sufficient to implement the Gibbs-Thomson law if the kink density is low enough. Subsurface ordering of liquids and growth of rough interfaces from melts is discussed. Crystals growing in microgravity from solution should be more perfect if they preferentially trap stress-inducing impurities, thus creating an impurity-depleted zone around themselves. Evidently, such a zone is developed only around the crystals growing in the absence of convection. Under terrestrial conditions, the self-purified depleted zone is destroyed by convection, the crystal traps more impurity and grows stressed. The stress relief causes mosaicity. In systems containing stress-inducing but poorly trapped impurities, the crystals grown in the absence of convection should be worse than those of their terrestrial counterparts.

  7. EDITORIAL: Quantum phenomena in Nanotechnology Quantum phenomena in Nanotechnology

    NASA Astrophysics Data System (ADS)

    Loss, Daniel

    2009-10-01

    Twenty years ago the Institute of Physics launched the journal Nanotechnology from its publishing house based in the home town of Paul Dirac, a legendary figure in the development of quantum mechanics at the turn of the last century. At the beginning of the 20th century, the adoption of quantum mechanical descriptions of events transformed the existing deterministic world view. But in many ways it also revolutionised the progress of research itself. For the first time since the 17th century when Francis Bacon established inductive reasoning as the means of advancing science from fact to axiom to law, theory was progressing ahead of experiments instead of providing explanations for observations that had already been made. Dirac's postulation of antimatter through purely theoretical investigation before its observation is the archetypal example of theory leading the way for experiment. The progress of nanotechnology and the development of tools and techniques that enabled the investigation of systems at the nanoscale brought with them many fascinating observations of phenomena that could only be explained through quantum mechanics, first theoretically deduced decades previously. At the nanoscale, quantum confinement effects dominate the electrical and optical properties of systems. They also render new opportunities for manipulating the response of systems. For example, a better understanding of these systems has enabled the rapid development of quantum dots with precisely determined properties, which can be exploited in a range of applications from medical imaging and photovoltaic solar cells to quantum computation, a radically new information technology being currently developed in many labs worldwide. As the first ever academic journal in nanotechnology, {\\it Nanotechnology} has been the forum for papers detailing progress of the science through extremely exciting times. In the early years of the journal, the investigation of electron spin led to the formulation

  8. Understanding empathy and related phenomena.

    PubMed

    Shamasundar, C

    1999-01-01

    Over a period of time, the author arrived at a few tentative postulates concerning empathy and related processes based on some of his experiences and observations. The central theme of these postulates is, firstly, that interpersonal interaction is an interaction of the personal-space fields. Secondly, empathy, therapeutic benefit, and the professional stress are all related to the same process of interpersonal interaction. This interaction takes place as an enmeshment of personal spaces of the interacting individuals, and involves transfer of a wide range of information in the affective, cognitive, and other areas. This is because the personal spaces have fieldlike qualities analogous to what Kurt Lewin described. Thus, such phenomena as empathy, therapeutic benefit, professional stress are all consequences of the same process. It is possible to substantiate these postulates by diverse evidences in the published literature. The natural consequences of such an interpersonal interaction are empathic understanding, transfer of mood states (like hope, distress or expectancy), affective states (like anxiety, sadness, anger or hostility), ideas, images and even attitudes and values, etc. This phenomenon of transfer can explain such processes as therapeutic benefit in individual and group settings, professional stress, shared delusions, and even experimenter bias. Whether one becomes aware of such transferred information or not depends upon the intent and sensitivity of the participants.

  9. Electronic phenomena at high pressure

    SciTech Connect

    Drickamer, H.G.

    1981-01-01

    High pressure research is undertaken either to investigate intrinsically high pressure phenomena or in order to get a better understanding of the effect of the chemical environment on properties or processes at one atmosphere. Studies of electronic properties which fall in each area are presented. Many molecules and complexes can assume in the excited state different molecular arrangements and intermolecular forces depending on the medium. Their luminescence emission is then very different in a rigid or a fluid medium. With pressure one can vary the viscosity of the medium by a factor of 10/sup 7/ and thus control the distribution and rate of crossing between the excited state conformations. In rare earth chelates the efficiency of 4f-4f emission of the rare earth is controlled by the feeding from the singlet and triplet levels of the organic ligand. These ligand levels can be strongly shifted by pressure. A study of the effect of pressure on the emission efficiency permits one to understand the effect of ligand chemistry at one atmosphere. At high pressure electronic states can be sufficiently perturbed to provide new ground states. In EDA complexes these new ground states exhibit unusual chemical reactivity and new products.

  10. Monitoring of Transient Lunar Phenomena

    NASA Astrophysics Data System (ADS)

    Barker, Timothy; Farber, Ryan; Ahrendts, Gary

    2014-06-01

    Transient Lunar Phenomena (TLP’s) are described as short-lived changes in the brightness of areas on the face of the Moon. TLP research is characterized by the inability to substantiate, reproduce, and verify findings. Our current research includes the analysis of lunar images taken with two Santa Barbara Instrument Group (SBIG) ST8-E CCD cameras mounted on two 0.36m Celestron telescopes. On one telescope, we are using a sodium filter, and on the other an H-alpha filter, imaging approximately one-third of the lunar surface. We are focusing on two regions: Hyginus and Ina. Ina is of particular interest because it shows evidence of recent activity (Schultz, P., Staid, M., Pieters, C. Nature, Volume 444, Issue 7116, pp. 184-186, 2006). A total of over 50,000 images have been obtained over approximately 35 nights and visually analyzed to search for changes. As of March, 2014, no evidence of TLPs has been found. We are currently developing a Matlab program to do image analysis to detect TLPs that might not be apparent by visual inspection alone.

  11. Conductance phenomena in microcrystalline cellulose

    NASA Astrophysics Data System (ADS)

    Nilsson, M.

    2006-02-01

    We have investigated the conduction phenomena in compacted tablets of cellulose with varying relative humidity (RH) with techniques such as Low Frequency Dielectric Spectroscopy (LFDS) and Transient Current (TC) at room temperature. Two exponential decaying regions in the transient current measurements indicate two ionic species contributing to the conduction mechanism. A high power-law exponent of 9 for the conductance with moisture content has been found. The mobility initially decreases with RH up to monolayer coverage, and further water vapor increases the mobility, indicating a blocking of available positions for the charge carrier ions. When the amount of water molecules present in the tablet increases one order of magnitude, the number of charge carriers increases 5-6 orders of magnitude, suggesting a transition from a power-law increase to a linear effective medium theory for the conduction. The charge carrier dependence on RH suggests that a percolating network of water molecules adsorbed to 6-OH units on the cellulose chain span through the sample. The conductivity mechanisms in cellulose are still not clear.

  12. Threshold phenomena in soft matter

    NASA Astrophysics Data System (ADS)

    Huang, Zhibin

    Although two different fields are covered, this thesis is mainly focused on some threshold behaviors in both liquid crystal field and fluid dynamic systems. A method of rubbed polyimide is used to obtain pretilt. Sufficiently strong rubbing of a polyimide (SE-1211) results in a large polar pretilt of liquid crystal director with respect to the homeotropic orientation. There exists a threshold rubbing strength required to induce nonzero pretilt. For the homologous liquid crystal series alkyl-cyanobyphenyl, we found that the threshold rubbing strength is a monotonic function of the number of methylene units. A dual easy axis model is then used to explain the results. Freedericksz transition measurements have been used to determine the quadratical and quartic coefficients associated with the molecules' tilt with respect to the layer normal in surface-induced smectic layers in the nematic phase above the smectic-A-nematic phase transition temperature. Both the quadratic and quartic coefficients are consistent with the scaling relationship as predicted in theory, and their ratio is approximately constant. A Rayleigh-Taylor instability experiment is performed by using a magnetic field gradient to draw down a low density but highly paramagnetic fluid below a more dense fluid in a Hele-Shaw cell. When turning off the magnetic field, the RT instability occurs in situ and the growth of the most unstable wavevector is measured as a function of time. The wavelength of the RT instability along with the growth rate was measured as a function of capillary number (which is related to the density difference and interfacial tension between two fluids). A theory for the instability that permits different viscosities for two immiscible fluids was developed, and good agreement was found with the experimental results. The technique of magnetic levitation promises to broaden significantly the accessible parameter space of gravitational interfacial instability experiments. A method is

  13. Mechanics of transport phenomena in multi-component sessile drops with solidification

    NASA Technical Reports Server (NTRS)

    Su, Yeong-Jen; Yang, Wen-Jei; Liu, Jiaching

    1990-01-01

    The mechanics of transport phenomena in multicomponent sessile drops with internal solidification is determined on the basis of an experimental study. A shadowgraph-schlieren system and a microscope-video system are used for the study. It is suggested that present data can be used to enhance the solid or crystal quality in a reduced-gravity environment where both thermo- and diffuso-capillary effects of solidification and crystal growth are dominant.

  14. Surface energies of elemental crystals.

    PubMed

    Tran, Richard; Xu, Zihan; Radhakrishnan, Balachandran; Winston, Donald; Sun, Wenhao; Persson, Kristin A; Ong, Shyue Ping

    2016-09-13

    The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal's equilibrium shape. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. In this work, we present the largest database of calculated surface energies for elemental crystals to date. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. Well-known reconstruction schemes are also accounted for. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials.

  15. Intrinsic interfacial phenomena in manganite heterostructures.

    PubMed

    Vaz, C A F; Walker, F J; Ahn, C H; Ismail-Beigi, S

    2015-04-01

    We review recent advances in our understanding of interfacial phenomena that emerge when dissimilar materials are brought together at atomically sharp and coherent interfaces. In particular, we focus on phenomena that are intrinsic to the interface and review recent work carried out on perovskite manganites interfaces, a class of complex oxides whose rich electronic properties have proven to be a useful playground for the discovery and prediction of novel phenomena.

  16. Observation of Celestial Phenomena in Ancient China

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochun

    Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

  17. Physicochemical principles of high-temperature crystallization and single crystal growth methods

    NASA Astrophysics Data System (ADS)

    Bagdasarov, Kh. S.

    The mechanisms of crystal growth are reviewed, with attention given to the physicochemical reactions taking place in the melt near the phase boundary; phenomena determining physical and chemical kinetics directly at the growth front; solid-phase processes occurring within the crystal. Methods for growing refractory single crystals are discussed with particular reference to the Verneuil method, zone melting, Czhochralskii growth, horizontal directional solidification, and the Stockbarger method. Methods for growing crystals of complex geometrical shapes are also discussed.

  18. Functional possibilities of nonlinear crystals for frequency conversion: uniaxial crystals

    SciTech Connect

    Andreev, Yu M; Arapov, Yu D; Kasyanov, I V; Grechin, S G; Nikolaev, P P

    2016-01-31

    The method and results of the analysis of phase-matching and nonlinear properties for all point groups of symmetry of uniaxial crystals that determine their functional possibilities for solving various problems of nonlinear frequency conversion of laser radiation are presented. (nonlinear optical phenomena)

  19. Analytics of crystal growth in space

    NASA Technical Reports Server (NTRS)

    Wilcox, W. R.; Chang, C. E.; Shlichta, P. J.; Chen, P. S.; Kim, C. K.

    1974-01-01

    Two crystal growth processes considered for spacelab experiments were studied to anticipate and understand phenomena not ordinarily encountered on earth. Computer calculations were performed on transport processes in floating zone melting and on growth of a crystal from solution in a spacecraft environment. Experiments intended to simulate solution growth at micro accelerations were performed.

  20. Understanding the Physics of changing mass phenomena

    NASA Astrophysics Data System (ADS)

    Ellermeijer, A. L.

    2008-05-01

    Changing mass phenomena, like a falling chain or a bungee jumper, might give surprising results, even for experienced physicists. They have resulted in hot discussions in journals, in which for instance Physics professors claim the impossibility of an acceleration larger then g in case of a bungee jumper. These phenomena are also interesting as topics for challenging student projects, and used as such by Dutch high school students. I will take these phenomena as the context in which I like to demonstrate the possibilities of ICT in the learning process of physics. Especially dynamical modeling enables us to describe these phenomena in an elegant way and with knowledge of high school mathematics. Furthermore tools for video-analysis and data from measurements with sensors allow us to study the phenomena in experiments. This example demonstrates the level of implementation of ICT in Physics Education in The Netherlands [1].

  1. X-ray Microscopic Characterization of Protein Crystals

    NASA Technical Reports Server (NTRS)

    Hu, Z. W.; Holmes, A.; Thomas, B.R.; Chernov, a. A.; Chu, Y. S.; Lai, B.

    2004-01-01

    The microscopic mapping of the variation in degree of perfection and in type of defects in entire protein crystals by x-rays may well be a prerequisite for better understanding causes of lattice imperfections, the growth history, and properties of protein crystals. However, x-ray microscopic characterization of bulk protein crystals, in the as-grown state, is frequently more challenging than that of small molecular crystals due to the experimental difficulties arising largely from the unique features possessed by protein crystals. In this presentation, we will illustrate ssme recent activities in employing coherence-based phase contrast x-ray imaging and high-angular-resolution diffraction techniques for mapping microdefects and the degree of perfection of protein crystals, and demonstrate a correlation between crystal perfection, diffraction phenomena., and crystallization conditions. The observed features and phenomena will be discussed in context to gain insight into the nature of defects, nucleation and growth, and the properties of protein crystals.

  2. Crystal Meth

    MedlinePlus

    ... from Other Parents Stories of Hope Crystal meth Crystal meth Story of Hope by giovanni January 3, ... about my drug addiction having to deal with Crystal meth. I am now in recovery and fighting ...

  3. Crystal Meth

    MedlinePlus

    ... Navigation Home / Stories of Hope / Crystal meth Crystal meth Story Of Hope By giovanni January 3rd, 2013 ... my drug addiction having to deal with Crystal meth. I am now in recovery and fighting my ...

  4. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  5. Synchronization Phenomena and Epoch Filter of Electroencephalogram

    NASA Astrophysics Data System (ADS)

    Matani, Ayumu

    Nonlinear electrophysiological synchronization phenomena in the brain, such as event-related (de)synchronization, long distance synchronization, and phase-reset, have received much attention in neuroscience over the last decade. These phenomena contain more electrical than physiological keywords and actually require electrical techniques to capture with electroencephalography (EEG). For instance, epoch filters, which have just recently been proposed, allow us to investigate such phenomena. Moreover, epoch filters are still developing and would hopefully generate a new paradigm in neuroscience from an electrical engineering viewpoint. Consequently, electrical engineers could be interested in EEG once again or from now on.

  6. Surface energies of elemental crystals

    NASA Astrophysics Data System (ADS)

    Tran, Richard; Xu, Zihan; Radhakrishnan, Balachandran; Winston, Donald; Sun, Wenhao; Persson, Kristin A.; Ong, Shyue Ping

    2016-09-01

    The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal’s equilibrium shape. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. In this work, we present the largest database of calculated surface energies for elemental crystals to date. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. Well-known reconstruction schemes are also accounted for. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials.

  7. Perspective: Emergent magnetic phenomena at interfaces

    SciTech Connect

    Suzuki, Yuri

    2015-06-01

    The discovery of emergent magnetic phenomena is of fundamental and technological interest. This perspective highlights recent promising examples of emergent ferromagnetism at complex oxide interfaces in the context of spin based electronics.

  8. Classifying prion and prion-like phenomena.

    PubMed

    Harbi, Djamel; Harrison, Paul M

    2014-01-01

    The universe of prion and prion-like phenomena has expanded significantly in the past several years. Here, we overview the challenges in classifying this data informatically, given that terms such as "prion-like", "prion-related" or "prion-forming" do not have a stable meaning in the scientific literature. We examine the spectrum of proteins that have been described in the literature as forming prions, and discuss how "prion" can have a range of meaning, with a strict definition being for demonstration of infection with in vitro-derived recombinant prions. We suggest that although prion/prion-like phenomena can largely be apportioned into a small number of broad groups dependent on the type of transmissibility evidence for them, as new phenomena are discovered in the coming years, a detailed ontological approach might be necessary that allows for subtle definition of different "flavors" of prion / prion-like phenomena.

  9. Analysis of nuclear reactor instability phenomena

    SciTech Connect

    Lahey, R.T. Jr.

    1993-01-01

    The phenomena known as density-wave instability often occurs in phase change systems, such as boiling water nuclear reactors (BWRS). Our current understanding of density-wave oscillations is in fairly good shape for linear phenomena (eg, the onset of instabilities) but is not very advanced for non-linear phenomena [Lahey and Podowski, 1989]. In particular, limit cycle and chaotic instability modes are not well understood in boiling systems such as current and advanced generation BWRs (eg, SBWR). In particular, the SBWR relies on natural circulation and is thus inherently prone to problems with density-wave instabilities. The purpose of this research is to develop a quantitative understanding of nonlinear nuclear-coupled density-wave instability phenomena in BWRS. This research builds on the work of Achard et al [1985] and Clausse et al [1991] who showed, respectively, that Hopf bifurcations and chaotic oscillations may occur in boiling systems.

  10. Canister storage building natural phenomena design loads

    SciTech Connect

    Tallman, A.M.

    1996-02-01

    This document presents natural phenomena hazard (NPH) loads for use in the design and construction of the Canister Storage Building (CSB), which will be located in the 200 East Area of the Hanford Site.

  11. Collective Phenomena in Macroscopic Systems

    NASA Astrophysics Data System (ADS)

    Bertin, G.; Pozzoli, R.; Romé, M.; Sreenivasan, K. R.

    2007-08-01

    for high and low B plasmas / E. Tassi, P. J. Morrison and D. Grasso -- Non locality of collective effects related to dynamical friction in elliptical galaxies / S.E. Arena and G. Bertin -- Evolution of a satellite dragged in by dynamical friction towards the center of a galaxy / S.E. Arena, G. Bertin and T. Liseykina -- Investigation of free decaying turbulence in a trapped pure electron plasma / G. Bettega ... [et al.] -- Structures of charge sheaths and transition layers in ion sources / M. Cavenago -- Generation of plasma perturbations under collisionless interaction of super-Alfvenic flows / G. Dudnikova, T. Liseykina and K. Vshivkov -- Program package for 3D Pic model of plasma fiber / P. Kulhanek and D. Bren -- A Stochastic approach to generalized quantum dynamics with collective long-range forces / A. Lavagno -- Filling of Electrostatic Plasma Lens for Ion-Beam-Focusing by electrons against direction of electric field due to non-linear vortex behavior / V. Maslov -- Thermal barrier formation for plasma electrons and ions in kind of connected solitary dip and hump of electric potential near ECR points in cylindrical trap / V. Maslov ... [et al.] -- Excitation of solitary wake-field by relativistic electron bunch and laser pulse / V. Maslov, A. Egorov and I. Onishchenko -- Enhancement of ion beam charge states by electron vortices in a plasma optical device / V. Maslov, A. Goncharov and I. Brown -- Wake-field mechanism of ion quasi-crystal formation in nonequilibrium dusty plasmas of technological devices / V. Maslov ... [et al.] -- Spiral perturbation in separator for extraction of heavy drops from plasma flow / V. Maslov ... [et al.] -- Fractional relaxation equation from AC universality in disordered solids / A. V. Milovanov, K. Rypdal and J. J. Rasmussen -- Vortices in two-dimensional rotating bose-Einstein condensates / T. Rindler-Daller -- Studying instability of 3D collisionless systems on Stochastic trajectories / V. N. Snytnikov and E. A. Kuksheva

  12. Hybrid colloidal plasmonic-photonic crystals.

    PubMed

    Romanov, Sergei G; Korovin, Alexander V; Regensburger, Alois; Peschel, Ulf

    2011-06-17

    We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.

  13. Photon management of GaN-based optoelectronic devices via nanoscaled phenomena

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Lin; Lai, Kun-Yu; Lee, Ming-Jui; Liao, Yu-Kuang; Ooi, Boon S.; Kuo, Hao-Chung; He-Hau, Jr.

    2016-09-01

    Photon management is essential in improving the performances of optoelectronic devices including light emitting diodes, solar cells and photo detectors. Beyond the advances in material growth and device structure design, photon management via nanoscaled phenomena have also been demonstrated as a promising way for further modifying/improving the device performance. The accomplishments achieved by photon management via nanoscaled phenomena include strain-induced polarization field management, crystal quality improvement, light extraction/harvesting enhancement, radiation pattern control, and spectrum management. In this review, we summarize recent development, challenges and underlying physics of photon management in GaN-based light emitting diodes and solar cells.

  14. Atomistic simulation of transport phenomena in nanoelectronic devices.

    PubMed

    Luisier, Mathieu

    2014-07-07

    Computational chemistry deals with the first-principles calculation of electronic and crystal structures, phase diagrams, charge distributions, vibrational frequencies, or ion diffusivity in complex molecules and solids. Typically, none of these numerical experiments allows for the calculation of electrical currents under the influence of externally applied voltages. To address this issue, there is an imperative need for an advanced simulation approach capable of treating all kind of transport phenomena (electron, energy, momentum) at a quantum mechanical level. The goal of this tutorial review is to give an overview of the "quantum transport" (QT) research activity, introduce specific techniques such as the Non-equilibrium Green's Function (NEGF) formalism, describe their basic features, and underline their strengths and weaknesses. Three examples from the nanoelectronics field have been selected to illustrate the insight provided by quantum transport simulations. Details are also given about the numerical algorithms to solve the NEGF equations and about strategies to parallelize the workload on supercomputers.

  15. Crystal Growth Rate Dispersion: A Predictor of Crystal Quality in Microgravity?

    NASA Technical Reports Server (NTRS)

    Kephart, Richard D.; Judge, Russell A.; Snell, Edward H.; vanderWoerd, Mark J.

    2003-01-01

    In theory macromolecular crystals grow through a process involving at least two transport phenomena of solute to the crystal surface: diffusion and convection. In absence of standard gravitational forces, the ratio of these two phenomena can change and explain why crystal growth in microgravity is different from that on Earth. Experimental evidence clearly shows, however, that crystal growth of various systems is not equally sensitive to reduction in gravitational forces, leading to quality improvement in microgravity for some crystals but not for others. We hypothesize that the differences in final crystal quality are related to crystal growth rate dispersion. If growth rate dispersion exists on Earth, decreases in microgravity, and coincides with crystal quality improvements then this dispersion is a predictor for crystal quality improvement. In order to test this hypothesis, we will measure growth rate dispersion both in microgravity and on Earth and will correlate the data with previously established data on crystal quality differences for the two environments. We present here the first crystal growth rate measurement data for three proteins (lysozyme, xylose isomerase and human recombinant insulin), collected on Earth, using hardware identical to the hardware to be used in microgravity and show how these data correlate with crystal quality improvements established in microgravity.

  16. [Spiritual phenomena occurring in everybody and health].

    PubMed

    Krsiak, M

    2008-01-01

    The past several years have seen an explosion of research in the area of spirituality and health. However, confusion and incomprehension of the conception of spirituality (e.g. confounding spirituality with various conventional views on religiousness) hampers better understanding in this area. The present paper proposes definition of spiritual phenomena in man based on natural epistemological and instrumental criteria (whether a certain phenomenon can be objectively known and evoked): spiritual phenomena in man are those, which cannot be objectively known nor evoked, but which act (e.g., love, idea). Spiritual phenomena can be really known only in the self ("in spirit"). Objectively known can be only manifestations of spiritual phenomena. Some attributes of love (e.g. its personal uniqueness) or ideas (e.g., sense of own life) whose satisfaction appears to be important for health are briefly outlined. A review of some frequently cited recent papers investigating the role of spirituality in health and discussion of frequent pitfalls in this area is given. Spirituality is a universal human phenomenon. All human beings, secular or religious, encounter with spiritual phenomena. Although the present conception of spirituality distances from some conventional views on religiousness, it is not atheistic. On the contrary, it accommodates the basic religious concept "God is love". Conceptual clarification is essential for further progress in the study of impact of spirituality on health.

  17. Diversity of threshold phenomena in geophysical media

    NASA Astrophysics Data System (ADS)

    Guglielmi, A. V.

    2017-01-01

    The sample analysis of threshold phenomena in the lithosphere, atmosphere, and magnetosphere is conducted. The phenomena due to the flow of electric current and pore fluid in the rocks are considered, the scenario of wind-driven generation of atmospheric electricity is suggested, and the model of the geomagnetic storm time Dst variation is analyzed. An important general conclusion consists in the fact that in the geophysical media there is a wide class of threshold phenomena that are affine with phase transitions of the second kind. These phenomena are also related to the critical transitions in self-oscillatory systems with soft self-excitation. The integral representation of bifurcation diagrams for threshold phenomena is suggested. This provides a simple way to take into account the influence of the fluctuations on the transition of a system through the threshold. Fluctuations remove singularity at the threshold point and, generally, lead to a certain shifting of the threshold. The question concerning the hard transition through the threshold and several aspects of modeling the blow-up instability which is presumed to occasionally develop in the geophysical media are discussed.

  18. Anomalous Light Phenomena vs. Bioelectric Brain Activity

    NASA Astrophysics Data System (ADS)

    Teodorani, M.; Nobili, G.

    We present a research proposal concerning the instrumented investigation of anomalous light phenomena that are apparently correlated with particular mind states, such as prayer, meditation or psi. Previous research by these authors demonstrate that such light phenomena can be monitored and measured quite efficiently in areas of the world where they are reported in a recurrent way. Instruments such as optical equipment for photography and spectroscopy, VLF spectrometers, magnetometers, radar and IR viewers were deployed and used massively in several areas of the world. Results allowed us to develop physical models concerning the structural and time-variable behaviour of light phenomena, and their kinematics. Recent insights and witnesses have suggested to us that a sort of "synchronous connection" seems to exist between plasma-like phenomena and particular mind states of experiencers who seem to trigger a light manifestation which is very similar to the one previously investigated. The main goal of these authors is now aimed at the search for a concrete "entanglement-like effect" between the experiencer's mind and the light phenomena, in such a way that both aspects are intended to be monitored and measured simultaneously using appropriate instrumentation. The goal of this research project is twofold: a) to verify quantitatively the existence of one very particular kind of mind-matter interaction and to study in real time its physical and biophysical manifestations; b) to repeat the same kind of experiment using the same test-subject in different locations and under various conditions of geomagnetic activity.

  19. The making of extraordinary psychological phenomena.

    PubMed

    Lamont, Peter

    2012-01-01

    This article considers the extraordinary phenomena that have been central to unorthodox areas of psychological knowledge. It shows how even the agreed facts relating to mesmerism, spiritualism, psychical research, and parapsychology have been framed as evidence both for and against the reality of the phenomena. It argues that these disputes can be seen as a means through which beliefs have been formulated and maintained in the face of potentially challenging evidence. It also shows how these disputes appealed to different forms of expertise, and that both sides appealed to belief in various ways as part of the ongoing dispute about both the facts and expertise. Finally, it shows how, when a formal Psychology of paranormal belief emerged in the twentieth century, it took two different forms, each reflecting one side of the ongoing dispute about the reality of the phenomena.

  20. Theories of dynamical phenomena in sunspots

    NASA Technical Reports Server (NTRS)

    Thomas, J. H.

    1981-01-01

    Attempts that have been made to understand and explain observed dynamical phenomena in sunspots within the framework of magnetohydrodynamic theory are surveyed. The qualitative aspects of the theory and physical arguments are emphasized, with mathematical details generally avoided. The dynamical phenomena in sunspots are divided into two categories: aperiodic (quasi-steady) and oscillatory. For each phenomenon discussed, the salient observational features that any theory should explain are summarized. The two contending theoretical models that can account for the fine structure of the Evershed motion, namely the convective roll model and the siphon flow model, are described. With regard to oscillatory phenomena, attention is given to overstability and oscillatory convection, umbral oscillations and flashes. penumbral waves, five-minute oscillations in sunspots, and the wave cooling of sunspots.

  1. Self field electromagnetism and quantum phenomena

    NASA Astrophysics Data System (ADS)

    Schatten, Kenneth H.

    1994-07-01

    Quantum Electrodynamics (QED) has been extremely successful inits predictive capability for atomic phenomena. Thus the greatest hope for any alternative view is solely to mimic the predictive capability of quantum mechanics (QM), and perhaps its usefulness will lie in gaining a better understanding of microscopic phenomena. Many ?paradoxes? and problematic situations emerge in QED. To combat the QED problems, the field of Stochastics Electrodynamics (SE) emerged, wherein a random ?zero point radiation? is assumed to fill all of space in an attmept to explain quantum phenomena, without some of the paradoxical concerns. SE, however, has greater failings. One is that the electromagnetic field energy must be infinit eto work. We have examined a deterministic side branch of SE, ?self field? electrodynamics, which may overcome the probelms of SE. Self field electrodynamics (SFE) utilizes the chaotic nature of electromagnetic emissions, as charges lose energy near atomic dimensions, to try to understand and mimic quantum phenomena. These fields and charges can ?interact with themselves? in a non-linear fashion, and may thereby explain many quantum phenomena from a semi-classical viewpoint. Referred to as self fields, they have gone by other names in the literature: ?evanesccent radiation?, ?virtual photons?, and ?vacuum fluctuations?. Using self fields, we discuss the uncertainty principles, the Casimir effects, and the black-body radiation spectrum, diffraction and interference effects, Schrodinger's equation, Planck's constant, and the nature of the electron and how they might be understood in the present framework. No new theory could ever replace QED. The self field view (if correct) would, at best, only serve to provide some understanding of the processes by which strange quantum phenomena occur at the atomic level. We discuss possible areas where experiments might be employed to test SFE, and areas where future work may lie.

  2. Local phenomena, chapter 3, part C

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Oceanic and coastal phenomena with dimensions ranging to 100 km are dealt with. The two major categories discussed are waves, their generation and dynamics and ocean-land related problems. The dynamics, of surface waves in both capillary and gravity ranges indicates that microwave technology provides a superior means of measuring simultaneously the spatial and temporal properties of ocean waves. The need for basic studies of physical phenomena in support of active microwave sensing is indicated. Active microwave scattering from surface waves is discussed in terms of wave dynamics.

  3. Relaxation Phenomena in Optically Pumped Mercury Isotopes.

    DTIC Science & Technology

    1980-08-15

    AD-AIFIG 332 SINGER CO LITTLE FALLS NJ KEARFOTT DIV F /G 20/10 RELAXATION PHENOMENA IN OPTICALLY PUMPED MERCURY ISOTOPES.(U) AUG 80 P A HEIMANN, J H...2. GVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER 7 MOSRqr 80 - 7 44 1 j D,&s~ *> T4iTLE (and SubtUte; S. TYPE O F REPOR ൏ APER_2-VA Relaxation...Phenomena in Optically Interim SAticJepait./ Pupd__uyIooe. 1 Jul R79- Jun. l90 ’ 9 PEFORMNG OGANZA I ’AU!ANO C RSSEI. PORAM EMNd󈧰 T. NOJ ECT RS 7

  4. Phenomena at hot-wire electrodes.

    PubMed

    Gründler, P

    2000-06-01

    An overview is given describing phenomena at heated microelectrodes where matter and heat energy are simultaneously emitted into the solution. With controlled electric heating, virtual "quiescent" periods as well as ones with constant streaming conditions are found that depend on the heating time. A close look at a permanently heated wire reveals a well defined structure with stationary concentration, temperature and flow rate profiles. The observed phenomena can be utilised for analytical measurements, e.g. with the novel method "Temperature Pulse Voltammetry" (TPV).

  5. Fundamental investigation of duct/ESP phenomena

    SciTech Connect

    Brown, C.A. ); Durham, M.D. ); Sowa, W.A. . Combustion Lab.); Himes, R.M. ); Mahaffey, W.A. )

    1991-10-21

    Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

  6. Crystallization modifiers in lipid systems.

    PubMed

    Ribeiro, Ana Paula Badan; Masuchi, Monise Helen; Miyasaki, Eriksen Koji; Domingues, Maria Aliciane Fontenele; Stroppa, Valter Luís Zuliani; de Oliveira, Glazieli Marangoni; Kieckbusch, Theo Guenter

    2015-07-01

    Crystallization of fats is a determinant physical event affecting the structure and properties of fat-based products. The stability of these processed foods is regulated by changes in the physical state of fats and alterations in their crystallization behavior. Problems like polymorphic transitions, oil migration, fat bloom development, slow crystallization and formation of crystalline aggregates stand out. The change of the crystallization behavior of lipid systems has been a strategic issue for the processing of foods, aiming at taylor made products, reducing costs, improving quality, and increasing the applicability and stability of different industrial fats. In this connection, advances in understanding the complex mechanisms that govern fat crystallization led to the development of strategies in order to modulate the conventional processes of fat structuration, based on the use of crystallization modifiers. Different components have been evaluated, such as specific triacyglycerols, partial glycerides (monoacylglycerols and diacylglycerols), free fatty acids, phospholipids and emulsifiers. The knowledge and expertise on the influence of these specific additives or minor lipids on the crystallization behavior of fat systems represents a focus of current interest for the industrial processing of oils and fats. This article presents a comprehensive review on the use of crystallization modifiers in lipid systems, especially for palm oil, cocoa butter and general purpose fats, highlighting: i) the removal, addition or fractionation of minor lipids in fat bases; ii) the use of nucleating agents to modify the crystallization process; iii) control of crystallization in lipid bases by using emulsifiers. The addition of these components into lipid systems is discussed in relation to the phenomena of nucleation, crystal growth, morphology, thermal behavior and polymorphism, with the intention of providing the reader with a complete panorama of the associated mechanisms

  7. Optical properties of contrail-induced cirrus: discussion of unusual halo phenomena.

    PubMed

    Sussmann, R

    1997-06-20

    Photographs of a 120 degrees parhelion and a 22 degrees parhelion within persistent contrails are presented. These phenomena result from hexagonal plate-shaped ice crystals oriented horizontally with diameters between 300 mum and 2 mm. From our observations and reinvestigation of previous reports, we conclude that a subset of the population in persistent contrails can consist of highly regular, oriented, hexagonal plates or columns comparable to the most regular crystals in natural cirrus clouds. This is explained by measured ambient humidities below the formation conditions of natural cirrus. The resulting strong azimuthal variability of the scattering phase function impacts the radiative transfer through persistent contrails.

  8. Simple Phenomena, Slow Motion, Surprising Physics

    ERIC Educational Resources Information Center

    Koupil, Jan; Vicha, Vladimir

    2011-01-01

    This article describes a few simple experiments that are worthwhile for slow motion recording and analysis either because of interesting phenomena that can be seen only when slowed down significantly or because of the ability to do precise time measurements. The experiments described in this article are quite commonly done in Czech schools. All…

  9. Double Negative Materials (DNM), Phenomena and Applications

    DTIC Science & Technology

    2009-07-01

    9 Feynman , R. P., R. B. Leighton, and M. Sands. Quantum physics . Vol. 1 of The Feynman Lectures on Physics (Addison-Wesley, 1964...involved in justifying basic physical questions of causality, validity of the concept of negative index of refraction interpretation of experimental...Materials ......................................... 2-4 3. Basic Physics Phenomena

  10. Observations of Nonlinear Phenomena in Rotordynamics

    NASA Astrophysics Data System (ADS)

    Ehrich, Fredric F.

    Observations, analysis and understanding of nonlinear rotordynamic phenomena observed in aircraft gas turbine engines and other high-speed rotating machinery over the course of the author's career are described. Included are observations of sum-and-difference frequency response; effects of roller bearing clearance; relaxation oscillations; subharmonic response; chaotic response; and other generic nonlinear responses such as superharmonic and ultra-subharmonic response.

  11. Reduplication phenomena: body, mind and archetype.

    PubMed

    Garner, J

    2000-09-01

    The many biological and few psychodynamic explanations of reduplicative syndromes tend to have paralleled the dualism of the phenomenon with organic theories concentrating on form and dynamic theories emphasising content. This paper extends the contribution of psychoanalytic thinking to an elucidation of the form of the delusion. Literature on clinical and aetiological aspects of reduplicative phenomena is reviewed alongside a brief examination of psychoanalytic models not overtly related to these phenomena. The human experience of doubles as universal archetype is considered. There is an obvious aetiological role for brain lesions in delusional misidentifications, but psychological symptoms in an individual can rarely be reduced to an organic disorder. The splitting and doubling which occurs in the phenomena have resonances in cultural mythology and in theories from different schools of psychodynamic thought. For the individual patient and doctor, it is a diverting but potentially empty debate to endeavour to draw strict divisions between what is physical and what is psychological although both need to be investigated. Nevertheless, in patients in whom there is clear evidence of an organic contribution to aetiology a psychodynamic understanding may serve to illuminate the patient's experience. Organic brain disease or serious functional illness predispose to regression to earlier modes of archetypical and primitive thinking with concretization of the metaphorical and mythological world. Psychoanalytic models have a contribution in describing the form as well as the content of reduplicative phenomena.

  12. Solar Phenomena Associated with "EIT Waves"

    NASA Technical Reports Server (NTRS)

    Biesecker, D. A.; Myers, D. C.; Thompson, B. J.; Hammer, D. M.; Vourlidas, A.

    2002-01-01

    In an effort to understand what an 'EIT wave' is and what its causes are, we have looked for correlations between the initiation of EIT waves and the occurrence of other solar phenomena. An EIT wave is a coronal disturbance, typically appearing as a diffuse brightening propagating across the Sun. A catalog of EIT waves, covering the period from 1997 March through 1998 June, was used in this study. For each EIT wave, the catalog gives the heliographic location and a rating for each wave, where the rating is determined by the reliability of the observations. Since EIT waves are transient, coronal phenomena, we have looked for correlations with other transient, coronal phenomena: X-ray flares, coronal mass ejections (CMEs), and metric type II radio bursts. An unambiguous correlation between EIT waves and CMEs has been found. The correlation of EIT waves with flares is significantly weaker, and EIT waves frequently are not accompanied by radio bursts. To search for trends in the data, proxies for each of these transient phenomena are examined. We also use the accumulated data to show the robustness of the catalog and to reveal biases that must be accounted for in this study.

  13. Geophysical phenomena classification by artificial neural networks

    NASA Technical Reports Server (NTRS)

    Gough, M. P.; Bruckner, J. R.

    1995-01-01

    Space science information systems involve accessing vast data bases. There is a need for an automatic process by which properties of the whole data set can be assimilated and presented to the user. Where data are in the form of spectrograms, phenomena can be detected by pattern recognition techniques. Presented are the first results obtained by applying unsupervised Artificial Neural Networks (ANN's) to the classification of magnetospheric wave spectra. The networks used here were a simple unsupervised Hamming network run on a PC and a more sophisticated CALM network run on a Sparc workstation. The ANN's were compared in their geophysical data recognition performance. CALM networks offer such qualities as fast learning, superiority in generalizing, the ability to continuously adapt to changes in the pattern set, and the possibility to modularize the network to allow the inter-relation between phenomena and data sets. This work is the first step toward an information system interface being developed at Sussex, the Whole Information System Expert (WISE). Phenomena in the data are automatically identified and provided to the user in the form of a data occurrence morphology, the Whole Information System Data Occurrence Morphology (WISDOM), along with relationships to other parameters and phenomena.

  14. Displaying Computer Simulations Of Physical Phenomena

    NASA Technical Reports Server (NTRS)

    Watson, Val

    1991-01-01

    Paper discusses computer simulation as means of experiencing and learning to understand physical phenomena. Covers both present simulation capabilities and major advances expected in near future. Visual, aural, tactile, and kinesthetic effects used to teach such physical sciences as dynamics of fluids. Recommends classrooms in universities, government, and industry be linked to advanced computing centers so computer simulations integrated into education process.

  15. Intervention in Biological Phenomena via Feedback Linearization

    PubMed Central

    Fnaiech, Mohamed Amine; Nounou, Hazem; Nounou, Mohamed; Datta, Aniruddha

    2012-01-01

    The problems of modeling and intervention of biological phenomena have captured the interest of many researchers in the past few decades. The aim of the therapeutic intervention strategies is to move an undesirable state of a diseased network towards a more desirable one. Such an objective can be achieved by the application of drugs to act on some genes/metabolites that experience the undesirable behavior. For the purpose of design and analysis of intervention strategies, mathematical models that can capture the complex dynamics of the biological systems are needed. S-systems, which offer a good compromise between accuracy and mathematical flexibility, are a promising framework for modeling the dynamical behavior of biological phenomena. Due to the complex nonlinear dynamics of the biological phenomena represented by S-systems, nonlinear intervention schemes are needed to cope with the complexity of the nonlinear S-system models. Here, we present an intervention technique based on feedback linearization for biological phenomena modeled by S-systems. This technique is based on perfect knowledge of the S-system model. The proposed intervention technique is applied to the glycolytic-glycogenolytic pathway, and simulation results presented demonstrate the effectiveness of the proposed technique. PMID:23209459

  16. Temporal Phenomena in the Korean Conjunctive Constructions

    ERIC Educational Resources Information Center

    Kim, Dongmin

    2015-01-01

    The goal of this study is to characterize the temporal phenomena in the Korean conjunctive constructions. These constructions consist of three components: a verbal stem, a clause medial temporal suffix, and a clause terminal suffix. This study focuses on both the temporality of the terminal connective suffixes and the grammatical meanings of the…

  17. Wave Phenomena in an Acoustic Resonant Chamber

    ERIC Educational Resources Information Center

    Smith, Mary E.; And Others

    1974-01-01

    Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…

  18. Nitrous oxide sedation and sexual phenomena.

    PubMed

    Jastak, J T; Malamed, S F

    1980-07-01

    Nine cases of sexual phenomena that occurred with use of nitrous oxide and oxygen sedation are described. Dentists involved routinely used concentrations of nitrous oxide greater than 50% and did not have assistants in the room during dental procedures. Recommendations on the concentrations of nitrous oxide and the presence of an assistant are made.

  19. Crystal growing

    NASA Technical Reports Server (NTRS)

    Neville, J. P.

    1990-01-01

    One objective is to demonstrate the way crystals grow and how they affect the behavior of material. Another objective is to compare the growth of crystals in metals and nonmetals. The procedures, which involve a supersaturated solution of a salt that will separate into crystals on cooling and the pouring off of an eutectic solution to expose the crystals formed by a solid solution when an alloy of two metals forms a solid and eutectic solution on cooling, are described.

  20. Theory and experimental evidence of phonon domains and their roles in pre-martensitic phenomena

    NASA Astrophysics Data System (ADS)

    Jin, Yongmei M.; Wang, Yu U.; Ren, Yang

    2015-12-01

    Pre-martensitic phenomena, also called martensite precursor effects, have been known for decades while yet remain outstanding issues. This paper addresses pre-martensitic phenomena from new theoretical and experimental perspectives. A statistical mechanics-based Grüneisen-type phonon theory is developed. On the basis of deformation-dependent incompletely softened low-energy phonons, the theory predicts a lattice instability and pre-martensitic transition into elastic-phonon domains via 'phonon spinodal decomposition.' The phase transition lifts phonon degeneracy in cubic crystal and has a nature of phonon pseudo-Jahn-Teller lattice instability. The theory and notion of phonon domains consistently explain the ubiquitous pre-martensitic anomalies as natural consequences of incomplete phonon softening. The phonon domains are characterised by broken dynamic symmetry of lattice vibrations and deform through internal phonon relaxation in response to stress (a particular case of Le Chatelier's principle), leading to previously unexplored new domain phenomenon. Experimental evidence of phonon domains is obtained by in situ three-dimensional phonon diffuse scattering and Bragg reflection using high-energy synchrotron X-ray single-crystal diffraction, which observes exotic domain phenomenon fundamentally different from usual ferroelastic domain switching phenomenon. In light of the theory and experimental evidence of phonon domains and their roles in pre-martensitic phenomena, currently existing alternative opinions on martensitic precursor phenomena are revisited.

  1. The Correlation of Upwelling Phenomena and Ocean Sunfish Occurrences in Nusa Penida, Bali

    NASA Astrophysics Data System (ADS)

    Tito, C. K.; Susilo, E.

    2017-02-01

    Sea surface Temperature (SST) is an important oceanographic variable that can figure the upwelling phenomena. This study aims to determine the variability of SST in relation to upwelling phenomena in the Indian Ocean Southern of Bali Island and the Ocean Sunfish occurrences in the southern of Nusa Penida. Data loggers and remote sensing approach that record temperature was used. An Onset HOBO U20 Water Level Logger U20-001-02 was deployed in Crystal Bay (08°42‧S and 115°27‧E) at 8 meters depth. The daily field SST data were available from June 2011 to December 2014 with 30 minutes time interval. The monthly satellite images obtained from MODIS on board the Aqua satellite. While the ocean sunfish occurrences were based on rate of encounter (ROE) of previous works by Putra (2015) on July to October 2014. It was found that field data and MODIS have a high correlation (r=0.89) with Root Mean Square Error (RMSE=1.64°C). The upwelling phenomena characterized by the evidence of the colder water mass (SST < 25°C) and a higher concentration of chlorophyll-a, reach its peak in August to September. This phenomena coincidence with the high occurrences of Ocean Sunfish in Crystal Bay on August to October.

  2. Apoferritin crystals

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Dr. Alexander Chernov, of the Universities Space Research Association (USRA) and based at Marshall Space Flight Center, is investigating why protein crystals grown in space are, in about 20 percent of cases, better-ordered than those grown on the ground. They are testing the idea that the amount of impurities trapped by space-grown crystals may be different than the amount trapped by crystals grown on Earth because convection is negligible in microgravity. The concentrations or impurities in many space-grown crystals turned out to be several times lower than that in the terrestrial ones, sometimes below the detection limit. The ground-based experiment also showed that the amount of impurities per unit volume of the crystals was usually higher than the amount per unit volume of the solution. This means that a growing crystal actually purifies the solution in its immediate vicinity. Here, an impurity depletion zone is created around apoferritin crystals grown in gel, imitating microgravity conditions.

  3. Auroral Phenomena: Associated with auroras in complex ways are an extraordinary number of other physical phenomena.

    PubMed

    O'brien, B J

    1965-04-23

    The array of auroral phenomena involves all the basic types of physical phenomena: heat, light, sound, electricity and magnetism, atomic physics, and plasma physics. The uncontrollability, the unreproducibility, and the sheer enormity of the phenomena will keep experimentalists and theorists busy but unsatisfied for many years to come. The greatest challenge in this field of research is an adequate experimentally verifiable theory of the local energization of auroral particle fluxes. Once that is achieved, there is every likelihood that the multitude of correlations between auroral phenomena can be understood and appreciated. Until that time, however, such correlations are to be regarded like icebergs-the parts that can be seen are only a small fraction of the whole phenomenon, and it is the large unseen parts that can be dangerous to theorists and experimentalists alike.

  4. Frustrated pretransitional phenomena in aperiodic composites

    NASA Astrophysics Data System (ADS)

    Mariette, C.; Frantsuzov, Ilya; Wang, Bo; Guérin, L.; Rabiller, P.; Hollingsworth, Mark D.; Toudic, B.

    2016-11-01

    This paper reports on symmetry breaking in the aperiodic inclusion compound n -octadecane/urea and its isotopomer n -octadecane/urea-d4. The high-symmetry phase is described by a hexagonal rank-4 superspace group. Pretransitional phenomena in this crystallographic superspace reveal competing short-range-ordering phenomena within the high-symmetry phase. Very high-resolution diffraction data show that critical scattering appears at inequivalent points within the four-dimensional Brillouin zone, although the first phase transition at Tc1 near 158 K implies the condensation at only one of those points. The resulting superspace group remains of dimension 4. Two other phase transitions are reported at Tc2= 152.8 (4 ) K and Tc3= 109 (4 ) K in n -octadecane/urea-d4. The two low-symmetry phases that arise are described by rank-5 superspace groups.

  5. Study of non-equilibrium transport phenomena

    NASA Technical Reports Server (NTRS)

    Sharma, Surendra P.

    1987-01-01

    Nonequilibrium phenomena due to real gas effects are very important features of low density hypersonic flows. The shock shape and emitted nonequilibrium radiation are identified as the bulk flow behavior parameters which are very sensitive to the nonequilibrium phenomena. These parameters can be measured in shock tubes, shock tunnels, and ballistic ranges and used to test the accuracy of computational fluid dynamic (CFD) codes. Since the CDF codes, by necessity, are based on multi-temperature models, it is also desirable to measure various temperatures, most importantly, the vibrational temperature. The CFD codes would require high temperature rate constants, which are not available at present. Experiments conducted at the NASA Electric Arc-driven Shock Tube (EAST) facility reveal that radiation from steel contaminants overwhelm the radiation from the test gas. For the measurement of radiation and the chemical parameters, further investigation and then appropriate modifications of the EAST facility are required.

  6. Optimizing Laboratory Experiments for Dynamic Astrophysical Phenomena

    SciTech Connect

    Ryutov, D; Remington, B

    2005-09-13

    To make a laboratory experiment an efficient tool for the studying the dynamical astrophysical phenomena, it is desirable to perform them in such a way as to observe the scaling invariance with respect to the astrophysical system under study. Several examples are presented of such scalings in the area of magnetohydrodynamic phenomena, where a number of scaled experiments have been performed. A difficult issue of the effect of fine-scale dissipative structures on the global scale dissipation-free flow is discussed. The second part of the paper is concerned with much less developed area of the scalings relevant to the interaction of an ultra-intense laser pulse with a pre-formed plasma. The use of the symmetry arguments in such experiments is also considered.

  7. Oscillatory phenomena in a solar network region

    NASA Astrophysics Data System (ADS)

    Tsiropoula, Georgia; Tziotziou, Kostas; Schwartz, Pavol; Heinzel, Petr

    2009-03-01

    We examine oscillatory phenomena in a solar network region from multi-wavelength, observations obtained by the ground-based Dutch Open Telescope (DOT), and by instruments on the spacecraft Solar and Heliospheric Observatory (SoHO). The observations were obtained during a coordinated observing campaign on October 14, 2005. The temporal variations of the intensities and velocities in two distinct regions of the quiet Sun were investigated: one containing several dark mottles and the other several bright points defining the network boundaries (NB). The aim is to find similarities and/or differences in the oscillatory phenomena observed in these two regions and in different spectral lines formed from the chromosphere to the transition region, as well as propagation characteristics of waves.

  8. Transport Phenomena During Equiaxed Solidification of Alloys

    NASA Technical Reports Server (NTRS)

    Beckermann, C.; deGroh, H. C., III

    1997-01-01

    Recent progress in modeling of transport phenomena during dendritic alloy solidification is reviewed. Starting from the basic theorems of volume averaging, a general multiphase modeling framework is outlined. This framework allows for the incorporation of a variety of microscale phenomena in the macroscopic transport equations. For the case of diffusion dominated solidification, a simplified set of model equations is examined in detail and validated through comparisons with numerous experimental data for both columnar and equiaxed dendritic growth. This provides a critical assessment of the various model assumptions. Models that include melt flow and solid phase transport are also discussed, although their validation is still at an early stage. Several numerical results are presented that illustrate some of the profound effects of convective transport on the final compositional and structural characteristics of a solidified part. Important issues that deserve continuing attention are identified.

  9. Coherence Phenomena in Coupled Optical Resonators

    NASA Technical Reports Server (NTRS)

    Smith, D. D.; Chang, H.

    2004-01-01

    We predict a variety of photonic coherence phenomena in passive and active coupled ring resonators. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived, and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. We also demonstrate that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation, and use this result for the analysis of coupled-resonator photon dynamics. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators.

  10. Coronal Mass Ejections (CMEs) and Associated Phenomena

    NASA Astrophysics Data System (ADS)

    Manoharan, P. K.

    2008-10-01

    The Sun is the most powerful radio waves emitting object in the sky. The first documented recognition of the reception of radio waves from the Sun was made in 1942 by Hey.15 Since then solar radio observations, from ground-based and space-based instruments, have played a major role in understanding the physics of the Sun and fundamental physical processes of the solar radio emitting phenomena...

  11. Mirage phenomena in superconducting quantum corrals

    NASA Astrophysics Data System (ADS)

    Schmid, M.; Kampf, A. P.

    2005-09-01

    [Dedicated to Bernhard Mühlschlegel on the occasion ofhis 80th birthday]We investigate the local density of states and the order parameter structure inside an elliptic quantum corral on surfaces of isotropic and anisotropic superconductors. The Bogoliubov-de Gennes equations are solved in the presence of non-magnetic and magnetic impurities. We observe and discuss a variety of mirage and anti-mirage phenomena, which specifically reflect the nature of the superconducting pairing state.

  12. Experimental and Computational Characterization of Combustion Phenomena

    DTIC Science & Technology

    2006-05-01

    Fundamental Combustion Advanced Combustor Concepts Combustor Demonstration and Transition Figure 1. A design philosophy for transitioning basic...PFP UNCLASSIFIED [4] W.-W. Kim, S. Menon, and H. Mongia , “Large-Eddy Simulation of a Gas Turbine Combustor Flow,” Combust . Sci. Technol. 143, 25-62...AFRL-PR-WP-TM-2006-2131 EXPERIMENTAL AND COMPUTATIONAL CHARACTERIZATION OF COMBUSTION PHENOMENA Dr. James R. Gord Combustion Branch (AFRL

  13. Low-gravity experiments in critical phenomena

    NASA Technical Reports Server (NTRS)

    Moldover, Michael R.

    1986-01-01

    Studies of anomalous thermodynamic, transport, and structural phenomena in multibody systems near critical points are reviewed. The nomenclature used to describe critical points is explained; theoretical predictions of the thermodynamic properties of bulk systems are presented; and experimental tests of these predictions systems are discussed, considering equilibration and gravity effects in fluid systems and emphasizing the value of experiments conducted in a reduced-gravity environment. Several such experiments are described, and the available academic-research opportunities are briefly surveyed.

  14. Understanding Natural Language Descriptions of Physical Phenomena

    DTIC Science & Technology

    2004-05-07

    continue pouring coffee in it. People know all these things and can explain them with ease to others, but in most cases mathematical formulas are not...a part of these explanations. Instead of producing mathematical formulas or using formal representation languages, people use their own natural...in all these cases is on developing a conceptual understanding of the phenomena. The fact that human readers can learn about the physical world

  15. Multiscale Phenomena in Biology and Scientific Perspectivism

    NASA Astrophysics Data System (ADS)

    Callebaut, Werner

    2009-09-01

    This paper is a plea for considering scientific perspectivism as the appropriate philosophical stance to deal with a number of epistemological, methodological, and ontological challenges modelers of complex, multi-scale phenomena are facing. Broadly speaking, perspectivism is the philosophical position that one's access to the world through perception, experience, and reason is possible only through one's own perspective and interpretation. Scientific perspectivism extends this position to scientific.

  16. Natural phenomena hazards site characterization criteria

    SciTech Connect

    Not Available

    1994-03-01

    The criteria and recommendations in this standard shall apply to site characterization for the purpose of mitigating Natural Phenomena Hazards (wind, floods, landslide, earthquake, volcano, etc.) in all DOE facilities covered by DOE Order 5480.28. Criteria for site characterization not related to NPH are not included unless necessary for clarification. General and detailed site characterization requirements are provided in areas of meteorology, hydrology, geology, seismology, and geotechnical studies.

  17. Breakdown phenomena in high power klystrons

    SciTech Connect

    Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V.; Lee, T.G.

    1988-03-01

    In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented. 9 refs., 5 figs., 3 tabs.

  18. Thermal transport phenomena in nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-12-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications.

  19. Stability and restoration phenomena in competitive systems

    NASA Astrophysics Data System (ADS)

    Uechi, Lisa; Akutsu, Tatsuya

    2013-10-01

    A conservation law along with stability, recovering phenomena, and characteristic patterns of a nonlinear dynamical system have been studied and applied to physical, biological, and ecological systems. In our previous study, we proposed a system of symmetric 2n-dimensional conserved nonlinear differential equations. In this paper, competitive systems described by a 2-dimensional nonlinear dynamical (ND) model with external perturbations are applied to population cycles and recovering phenomena of systems from microbes to mammals. The famous 10-year cycle of population density of Canadian lynx and snowshoe hare is numerically analyzed. We find that a nonlinear dynamical system with a conservation law is stable and generates a characteristic rhythm (cycle) of population density, which we call the standard rhythm of a nonlinear dynamical system. The stability and restoration phenomena are strongly related to a conservation law and the balance of a system. The standard rhythm of population density is a manifestation of the survival of the fittest to the balance of a nonlinear dynamical system.

  20. Seismoelectric Phenomena in Fluid-Saturated Sediments

    SciTech Connect

    Block, G I; Harris, J G

    2005-04-22

    Seismoelectric phenomena in sediments arise from acoustic wave-induced fluid motion in the pore space, which perturbs the electrostatic equilibrium of the electric double layer on the grain surfaces. Experimental techniques and the apparatus built to study this electrokinetic (EK) effect are described and outcomes for studies of seismoelectric phenomena in loose glass microspheres and medium-grain sand are presented. By varying the NaCl concentration in the pore fluid, we measured the conductivity dependence of two kinds of EK behavior: (1) the electric fields generated within the samples by the passage of transmitted acoustic waves, and (2) the electromagnetic wave produced at the fluid-sediment interface by the incident acoustic wave. Both phenomena are caused by relative fluid motion in the sediment pores--this feature is characteristic of poroelastic (Biot) media, but not predicted by either viscoelastic fluid or solid models. A model of plane-wave reflection from a fluid-sediment interface using EK-Biot theory leads to theoretical predictions that compare well to the experimental data for both sand and glass microspheres.

  1. An interpretation of passive containment cooling phenomena

    SciTech Connect

    Chung, Bum-Jin; Kang, Chang-Sun,

    1995-09-01

    A simplified interpretation model for the cooling capability of the Westinghouse type PCCS is proposed in this paper. The PCCS domain was phenomenologically divided into 3 regions; water entrance effect region, asymptotic region, and air entrance effect region. The phenomena in the asymptotic region is focused in this paper. Due to the very large height to thickness ratio of the water film, the length of the asymptotic region is estimated to be over 90% of the whole domain. Using the analogy between heat and mass transfer phenomena in a turbulent situation, a new dependent variable combining temperature and vapor mass fraction was defined. The similarity between the PCCS phenomena, which contains the sensible and latent heat transfer, and the buoyant air flow on a vertical heated plate is derived. The modified buoyant coefficient and thermal conductivity were defined. Using these newly defined variable and coefficients, the modified correlation for the interfacial heat fluxes and the ratios of latent heat transfer to sensible heat transfer is established. To verify the accuracy of the correlation, the results of this study were compared with the results of other numerical analyses performed for the same configuration and they are well within the range of 15% difference.

  2. Lysozyme Crystal

    NASA Technical Reports Server (NTRS)

    2004-01-01

    To the crystallographer, this may not be a diamond but it is just as priceless. A Lysozyme crystal grown in orbit looks great under a microscope, but the real test is X-ray crystallography. The colors are caused by polarizing filters. Proteins can form crystals generated by rows and columns of molecules that form up like soldiers on a parade ground. Shining X-rays through a crystal will produce a pattern of dots that can be decoded to reveal the arrangement of the atoms in the molecules making up the crystal. Like the troops in formation, uniformity and order are everything in X-ray crystallography. X-rays have much shorter wavelengths than visible light, so the best looking crystals under the microscope won't necessarily pass muster under the X-rays. In order to have crystals to use for X-ray diffraction studies, crystals need to be fairly large and well ordered. Scientists also need lots of crystals since exposure to air, the process of X-raying them, and other factors destroy them. Growing protein crystals in space has yielded striking results. Lysozyme's structure is well known and it has become a standard in many crystallization studies on Earth and in space.

  3. An Undergraduate Laboratory Exercise for Studying Kinetics of Batch Crystallization

    ERIC Educational Resources Information Center

    Louhi­-Kultanen, Marjatta; Han, Bing; Nurkka, Annikka; Hatakka, Henry

    2015-01-01

    The present work describes an undergraduate laboratory exercise for improving understanding of fundamental phenomena in cooling crystallization. The exercise of nucleation and crystal growth kinetics supports learning of theories and models presented in lectures and calculation exercises. The teaching methodology incorporates precepts the…

  4. RNA Crystallization

    NASA Technical Reports Server (NTRS)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  5. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  6. Local polarization phenomena in In-doped CdTe x-ray detector arrays

    SciTech Connect

    Sato, Toshiyuki; Sato, Kenji; Ishida, Shinichiro; Kiri, Motosada; Hirooka, Megumi; Yamada, Masayoshi; Kanamori, Hitoshi

    1995-10-01

    Local polarization phenomena have been studied in detector arrays with the detector element size of 500 {micro}m x 500 {micro}m, which are fabricated from high-resistivity In-doped CdTe crystals grown by the vertical Bridgman technique. It has been found for the first time that a polarization effect, which is characterized by a progressive decrease of the pulse counting rate with increasing photon fluence, strongly depends on the detector elements, that is, the portion of crystals used. The influence of several parameters, such as the applied electric field strength, time, and temperature, on this local polarization effect is also investigated. From the photoluminescence measurements of the inhomogeneity of In dopant, it is concluded that the local polarization effect observed here originates from a deep level associated with In dopant in CdTe crystals.

  7. Computational crystallization.

    PubMed

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  8. Study of interfacial phenomena for bio/chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Min, Hwall

    This work presents the fundamental study of biological and chemical interfacial phenomena and (bio)chemical sensing applications using high frequency resonator arrays. To realize a versatile (bio)chemical sensing system for the fundamental study as well as their practical applications, the following three distinct components were studied and developed: i) detection platforms with high sensitivity, ii) novel innovative sensing materials with high selectivity, iii) analytical model for data interpretation. 8-pixel micromachined quartz crystal resonator (muQCR) arrays with a fundamental resonance frequency of 60 ¡V 90 MHz have been used to provide a reliable detection platform with high sensitivity. Room temperature ionic liquid (RTIL) has been explored and integrated into the sensing system as a smart chemical sensing material. The use of nanoporous gold (np-Au) enables the combination of the resonator and surface-enhanced Raman spectroscopy for both quantitative and qualitative measurement. A statistical model for the characterization of resonator behavior to study the protein adsorption kinetics is developed by random sequential adsorption (RSA) approach with the integration of an effective surface depletion theory. The investigation of the adsorption kinetics of blood proteins is reported as the fundamental study of biological phenomena using the proposed sensing system. The aim of this work is to study different aspects of protein adsorption and kinetics of adsorption process with blood proteins on different surfaces. We specifically focus on surface depletion effect in conjunction with the RSA model to explain the observed adsorption isotherm characteristics. A number of case studies on protein adsorption conducted using the proposed sensing system has been discussed. Effort is specifically made to understand adsorption kinetics, and the effect of surface on the adsorption process as well as the properties of the adsorbed protein layer. The second half of the

  9. Microgravity Transport Phenomena Experiment (MTPE) Overview

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.

    1999-01-01

    The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry

  10. Fast Particle Methods for Multiscale Phenomena Simulations

    NASA Technical Reports Server (NTRS)

    Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

    2000-01-01

    We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

  11. Rod Driven Frequency Entrainment and Resonance Phenomena

    PubMed Central

    Salchow, Christina; Strohmeier, Daniel; Klee, Sascha; Jannek, Dunja; Schiecke, Karin; Witte, Herbert; Nehorai, Arye; Haueisen, Jens

    2016-01-01

    A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α) of each volunteer in the range from 0.40 to 2.30∗α. Three hundred and six-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10∗α) and half of the alpha frequency (0.40–0.55∗α). No signs of resonance and frequency entrainment phenomena were revealed around 2.00∗α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30∗α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex. PMID:27588002

  12. Rod Driven Frequency Entrainment and Resonance Phenomena.

    PubMed

    Salchow, Christina; Strohmeier, Daniel; Klee, Sascha; Jannek, Dunja; Schiecke, Karin; Witte, Herbert; Nehorai, Arye; Haueisen, Jens

    2016-01-01

    A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α) of each volunteer in the range from 0.40 to 2.30(∗)α. Three hundred and six-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90-1.10(∗)α) and half of the alpha frequency (0.40-0.55(∗)α). No signs of resonance and frequency entrainment phenomena were revealed around 2.00(∗)α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30-2.30(∗)α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex.

  13. Simulating physical phenomena with a quantum computer

    NASA Astrophysics Data System (ADS)

    Ortiz, Gerardo

    2003-03-01

    In a keynote speech at MIT in 1981 Richard Feynman raised some provocative questions in connection to the exact simulation of physical systems using a special device named a ``quantum computer'' (QC). At the time it was known that deterministic simulations of quantum phenomena in classical computers required a number of resources that scaled exponentially with the number of degrees of freedom, and also that the probabilistic simulation of certain quantum problems were limited by the so-called sign or phase problem, a problem believed to be of exponential complexity. Such a QC was intended to mimick physical processes exactly the same as Nature. Certainly, remarks coming from such an influential figure generated widespread interest in these ideas, and today after 21 years there are still some open questions. What kind of physical phenomena can be simulated with a QC?, How?, and What are its limitations? Addressing and attempting to answer these questions is what this talk is about. Definitively, the goal of physics simulation using controllable quantum systems (``physics imitation'') is to exploit quantum laws to advantage, and thus accomplish efficient imitation. Fundamental is the connection between a quantum computational model and a physical system by transformations of operator algebras. This concept is a necessary one because in Quantum Mechanics each physical system is naturally associated with a language of operators and thus can be considered as a possible model of quantum computation. The remarkable result is that an arbitrary physical system is naturally simulatable by another physical system (or QC) whenever a ``dictionary'' between the two operator algebras exists. I will explain these concepts and address some of Feynman's concerns regarding the simulation of fermionic systems. Finally, I will illustrate the main ideas by imitating simple physical phenomena borrowed from condensed matter physics using quantum algorithms, and present experimental

  14. Shock Tunnel Studies of Scramjet Phenomena

    NASA Technical Reports Server (NTRS)

    Stalker, R. J.

    1996-01-01

    Work focussed on a large number of preliminary studies of supersonic combustion in a simple combustion duct - thrust nozzle combination, investigating effects of Mach number, equivalence ratio, combustor divergence, fuel injecting angle and other parameters with an influence on the combustion process. This phase lasted for some three or four years, during which strongest emphasis was placed on responding to the request for preliminary experimental information on high enthalpy effects, to support the technology maturation activities of the NASP program. As the need for preliminary data became less urgent, it was possible to conduct more systematic studies of high enthalpy combustion phenomena, and to initiate other projects aimed at improving the facilities and instrumentation used for studying scramjet phenomena at high enthalpies. The combustion studies were particularly directed towards hypersonic combustion, and to the effects of injecting fuel along the combustion chamber wall. A substantial effort was directed towards a study of the effect of scale on the supersonic combustion process. The influence of wave phenomena (both compression waves and expansion waves) on the realization of thrust from a supersonic combustion process was also investigated. The effect of chemical kinetics was looked into, particularly as it affected the composition of the test flow provided by a ground facility. The effect of injection of the fuel through wall orifices was compared with injection from a strut spanning the stream, and the effect of heating the fuel prior to injection was investigated. Studies of fuel-air mixing by shock impingement were also done, as well as mass spectrometer surveys of a combustion wake. The use of hypersonic nozzles with an expansion tube was investigated. A new method was developed for measuring the forces acting of a model in less than one millisecond. Also included in this report are listings of published journal papers and conference presentations.

  15. Autistic phenomena in The Adventures of Pinocchio.

    PubMed

    Smith, Adrian

    2017-04-01

    This paper seeks to demonstrate that the protagonist of Carlo Collodi's The Adventures of Pinocchio illustrates numerous autistic phenomena such as communication difficulties, sensory and perceptual distortions and mindblindness. While Pinocchio is viewed as a literary construct with contraindications of autism, it will be argued that his autistic traits are sufficient to suggest the possibility that Collodi had a partial intuition of the syndrome 60 years before it was identified by Leo Kanner. Approaching Collodi's text in this manner is taken as an opportunity to survey and reflect upon the psychoanalytic literature on autism and to position it in relation to contemporary theories from cognitive neuroscience.

  16. Heavenly Bodies and Phenomena in Petroglyphs

    NASA Astrophysics Data System (ADS)

    Tokhatyan, Karen

    2016-12-01

    In Armenian culture are amply reflected realities connected with Universe. Their figurative expressions are also petroglyphs in which there are representations of solar signs, swastika, Moon crescend, planets, stars, star groups, constellations, Milky Way, Earth. Among heavenly and atmospheric phenomena are: eclipce, meteor, comet, ligthning, cloud, rain and rainbow. There are many products of scientific thinking: stellar maps, calendars, compasses, astronomical records, Zodiac signs and ideograms. Thousands of the Armenian petroglyphs that were created millennia ago by an indigenous ethnos – Armenians, point to the significant place of celestial bodies and luminaries, especially the Sun, stars, and stellar constellations in our ancestors' cosmological perceptions.

  17. Relating Macroscopic Thermal Phenomena with Molecular Models

    NASA Astrophysics Data System (ADS)

    Laws, Priscilla W.

    2002-03-01

    A series of observations and activities have been developed to help students enrich their understanding of how physicists can use model building to construct self-consistent models of physical reality.* This talk will describe the instructional use of integrated microcomputer-based laboratory measurements of macroscopic phenomena and digital video analysis of simulated microscopic events to help students understand the ideal gas law, the first law of thermodynamics, and heat engines. *Workshop Physics Activity Guide (Module 3), P. Laws, (John Wiley and Sons, Inc., NY, 1997).

  18. Advances in modelling of condensation phenomena

    SciTech Connect

    Liu, W.S.; Zaltsgendler, E.; Hanna, B.

    1997-07-01

    The physical parameters in the modelling of condensation phenomena in the CANDU reactor system codes are discussed. The experimental programs used for thermal-hydraulic code validation in the Canadian nuclear industry are briefly described. The modelling of vapour generation and in particular condensation plays a key role in modelling of postulated reactor transients. The condensation models adopted in the current state-of-the-art two-fluid CANDU reactor thermal-hydraulic system codes (CATHENA and TUF) are described. As examples of the modelling challenges faced, the simulation of a cold water injection experiment by CATHENA and the simulation of a condensation induced water hammer experiment by TUF are described.

  19. Complex Synchronization Phenomena in Ecological Systems

    NASA Astrophysics Data System (ADS)

    Stone, Lewi; Olinky, Ronen; Blasius, Bernd; Huppert, Amit; Cazelles, Bernard

    2002-07-01

    Ecological and biological systems provide us with many striking examples of synchronization phenomena. Here we discuss a number of intriguing cases and attempt to explain them taking advantage of a modelling framework. One main focus will concern synchronized ecological end epidemiological cycles which have Uniform Phase growth associated with their regular recurrence, and Chaotic Amplitudes - a feature we term UPCA. Examples come from different areas and include decadal cycles of small mammals, recurrent viral epidemics such as childhood infections (eg., measles), and seasonally driven phytoplankton blooms observed in lakes and the oceans. A more detailed theoretical analysis of seasonally synchronized chaotic population cycles is presented.

  20. Layered phenomena in the mesopause region

    NASA Astrophysics Data System (ADS)

    Plane, J. M. C.; Bailey, S. M.; Baumgarten, G.; Rapp, M.

    2015-05-01

    This special issue of the Journal of Atmospheric and Solar-Terrestrial Physics comprises a collection of papers which were mostly presented at the 11th Layered Phenomena in the Mesopause Region (LPMR) Workshop, held at the University of Leeds between 29th July 2013 and 1st August 2013. The topics covered at the workshop included atmospheric dynamics, mesospheric ice clouds, meteoric metal layers, meteoric smoke particles, and airglow layers. There was also a session on the potential of planned sub-orbital spacecraft for making measurements in the mesosphere and lower thermosphere (MLT).

  1. On periodicity of solar wind phenomena

    NASA Technical Reports Server (NTRS)

    Verma, V. K.; Joshi, G. C.

    1995-01-01

    We have investigated the rate of occurrence of solar wind phenomena observed between 1972-1984 using power spectrum analysis. The data have been taken from the high speed solar wind (HSSW) streams catalogue published by Mavromichalaki et al. (1988). The power spectrum analysis of HSSW events indicate that HSSW stream events have a periodicity of 9 days. This periodicity of HSSW events is 1/3 of the 27 days period of coronal holes which are the major source of solar wind events. In our opinion the 9 days period may be the energy build up time to produce the HSSW stream events.

  2. Quenching phenomena in natural circulation loop

    SciTech Connect

    Umekawa, Hisashi; Ozawa, Mamoru; Ishida, Naoki

    1995-09-01

    Quenching phenomena has been investigated experimentally using circulation loop of liquid nitrogen. During the quenching under natural circulation, the heat transfer mode changes from film boiling to nucleate boiling, and at the same time flux changes with time depending on the vapor generation rate and related two-phase flow characteristics. Moreover, density wave oscillations occur under a certain operating condition, which is closely related to the dynamic behavior of the cooling curve. The experimental results indicates that the occurrence of the density wave oscillation induces the deterioration of effective cooling of the heat surface in the film and the transition boiling regions, which results in the decrease in the quenching velocity.

  3. Crystal Data

    National Institute of Standards and Technology Data Gateway

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  4. Growth dynamics of isotactic polypropylene single crystals during isothermal crystallization from a miscible polymeric solvent.

    PubMed

    Mehta, Rujul; Keawwattana, Wirunya; Kyu, Thein

    2004-02-22

    The present article presents a spatiotemporal growth of isotactic polypropylene (iPP) single crystals, melt crystallized from a polymeric solvent, i.e., poly (ethylene octene) copolymer that is known to be miscible with iPP. Optical and atomic force microscopic investigations reveal that the melt grown single crystals of iPP develop in the form of two parallel rows of crystal lamellae, but these crystals merge at the tips. To elucidate the mechanism of these emerging parallel rows of iPP crystals, a phase field model pertaining to solidification phenomena has been employed that involves a nonconserved crystal order parameter and a chain-tilting angle. This phase field model is based on the free energy of crystallization, having an asymmetric double well, and a tensorial surface free energy of the crystal interface coupled with a curvature elastic free energy that is possessed by the solid-liquid interface. The spatiotemporal simulation of iPP single crystal growth has been carried out on a square lattice based on the finite difference method for spatial steps and an explicit method for temporal steps with a periodic boundary condition. The appearance of the seemingly twin crystal is captured in the simulation, which may be attributed to the sector demarcation that is taking place in the anisotropically growing single crystal of iPP.

  5. Growth dynamics of isotactic polypropylene single crystals during isothermal crystallization from a miscible polymeric solvent

    NASA Astrophysics Data System (ADS)

    Mehta, Rujul; Keawwattana, Wirunya; Kyu, Thein

    2004-02-01

    The present article presents a spatiotemporal growth of isotactic polypropylene (iPP) single crystals, melt crystallized from a polymeric solvent, i.e., poly (ethylene octene) copolymer that is known to be miscible with iPP. Optical and atomic force microscopic investigations reveal that the melt grown single crystals of iPP develop in the form of two parallel rows of crystal lamellae, but these crystals merge at the tips. To elucidate the mechanism of these emerging parallel rows of iPP crystals, a phase field model pertaining to solidification phenomena has been employed that involves a nonconserved crystal order parameter and a chain-tilting angle. This phase field model is based on the free energy of crystallization, having an asymmetric double well, and a tensorial surface free energy of the crystal interface coupled with a curvature elastic free energy that is possessed by the solid-liquid interface. The spatiotemporal simulation of iPP single crystal growth has been carried out on a square lattice based on the finite difference method for spatial steps and an explicit method for temporal steps with a periodic boundary condition. The appearance of the seemingly twin crystal is captured in the simulation, which may be attributed to the sector demarcation that is taking place in the anisotropically growing single crystal of iPP.

  6. WHC natural phenomena hazards mitigation implementation plan

    SciTech Connect

    Conrads, T.J.

    1996-09-11

    Natural phenomena hazards (NPH) are unexpected acts of nature which pose a threat or danger to workers, the public or to the environment. Earthquakes, extreme winds (hurricane and tornado),snow, flooding, volcanic ashfall, and lightning strike are examples of NPH at Hanford. It is the policy of U.S. Department of Energy (DOE) to design, construct and operate DOE facilitiesso that workers, the public and the environment are protected from NPH and other hazards. During 1993 DOE, Richland Operations Office (RL) transmitted DOE Order 5480.28, ``Natural Phenomena Hazards Mitigation,`` to Westinghouse Hanford COmpany (WHC) for compliance. The Order includes rigorous new NPH criteria for the design of new DOE facilities as well as for the evaluation and upgrade of existing DOE facilities. In 1995 DOE issued Order 420.1, ``Facility Safety`` which contains the same NPH requirements and invokes the same applicable standards as Order 5480.28. It will supersede Order 5480.28 when an in-force date for Order 420.1 is established through contract revision. Activities will be planned and accomplished in four phases: Mobilization; Prioritization; Evaluation; and Upgrade. The basis for the graded approach is the designation of facilities/structures into one of five performance categories based upon safety function, mission and cost. This Implementation Plan develops the program for the Prioritization Phase, as well as an overall strategy for the implemention of DOE Order 5480.2B.

  7. Multiscale phenomena in the Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Surjalal Sharma, A.

    The multiscale phenomena in the Earth's magnetosphere have been studied using data from ground-based and space-borne measurements. The ground-based observations provide data over decades and are suitable for characterizing the inherent nature of the multiscale behavior and for studying the dynamical and statistical features. On the other hand, the spacecraft data provide in-situ observations of the processes. The multipoint measurements by Cluster have provided a new understanding of the plasma processes at microand meso-scales and the cross-scale coupling among them. The role of cross-scale coupling is evident in phenomena such as bursty bulk flows, flux ropes, and reconnection. The characteristic scales of the processes range from electron skin depth to MHD scales and the modeling of these processes need different physical models, such as kinetic, EMHD, Hall MHD, and MHD. The ground-based data have been used to develop models based on techniques of nonlinear science and yield predictive models which can be used for forecasting. These models characterize the magnetospheric dynaics and yield its global and multiscale aspects. The distribution of scales in the magnetosphere is studied using an extensive database of the solar wind and the magnetosphere. The distributions of the waiting times deviate significantly from a power law as well as stretched exponential distributions, and show a scaling with respect to the mean, indicating a limited role of long-term correlations in the magnetospheric dynamics.

  8. Animal network phenomena: insights from triadic games

    NASA Astrophysics Data System (ADS)

    Mesterton-Gibbons, Mike; Sherratt, Tom N.

    Games of animal conflict in networks rely heavily on computer simulation because analysis is difficult, the degree of difficulty increasing sharply with the size of the network. For this reason, virtually the entire analytical literature on evolutionary game theory has assumed either dyadic interaction or a high degree of symmetry, or both. Yet we cannot rely exclusively on computer simulation in the study of any complex system. So the study of triadic interactions has an important role to play, because triads are both the simplest groups in which asymmetric network phenomena can be studied and the groups beyond dyads in which analysis of population games is most likely to be tractable, especially when allowing for intrinsic variation. Here we demonstrate how such analyses can illuminate a variety of behavioral phenomena within networks, including coalition formation, eavesdropping (the strategic observation of contests between neighbors) and victory displays (which are performed by the winners of contests but not by the losers). In particular, we show that eavesdropping acts to lower aggression thresholds compared to games without it, and that victory displays to bystanders will be most intense when there is little difference in payoff between dominating an opponent and not subordinating.

  9. Nonlinear phenomena in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.

    2008-05-01

    We present a medley of results from the last three years on nonlinear phenomena in BECs [1]. These include exact dynamics of multi-component condensates in optical lattices [2], vortices and ring solitons [3], macroscopic quantum tunneling [4], nonlinear band theory [5], and a pulsed atomic soliton laser [6]. 1. Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment, ed. P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer-Verlag, 2008). 2. R. Mark Bradley, James E. Bernard, and L. D. Carr, e-print arXiv:0711.1896 (2007). 3. G. Herring, L. D. Carr, R. Carretero-Gonzalez, P. G. Kevrekidis, D. J. Frantzeskakis, Phys. Rev. A in press, e-print arXiv:0709.2193 (2007); L. D. Carr and C. W. Clark, Phys. Rev. A v. 74, p.043613 (2006); L. D. Carr and C. W. Clark, Phys. Rev. Lett. v. 97, p.010403 (2006). 4. L. D. Carr, M. J. Holland, and B. A. Malomed, J. Phys. B: At. Mol. Opt. Phys., v.38, p.3217 (2005) 5. B. T. Seaman, L. D. Carr, and M. J. Holland, Phys. Rev. A, v. 71, p.033622 (2005). 6. L. D. Carr and J. Brand, Phys. Rev. A, v.70, p.033607 (2004); L. D. Carr and J. Brand, Phys. Rev. Lett., v.92, p.040401 (2004).

  10. Emergent phenomena and partonic structure in hadrons

    NASA Astrophysics Data System (ADS)

    Roberts, Craig D.; Mezrag, Cédric

    2017-03-01

    Modern facilities are poised to tackle fundamental questions within the Standard Model, aiming to reveal the nature of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between these two, key emergent phenomena. There is strong evidence to suggest that they are intimately connected with the appearance of momentum-dependent masses for gluons and quarks in QCD, which are large in the infrared: mg 500MeV and Mq 350MeV. DCSB, expressed in the dynamical generation of a dressed-quark mass, has an enormous variety of verifiable consequences, including an enigmatic result that the properties of the (almost) massless pion are the cleanest expression of the mechanism which is responsible for almost all the visible mass in the Universe. This contribution explains that these emergent phenomena are expressed with particular force in the partonic structure of hadrons, e.g. in valence-quark parton distribution amplitudes and functions, and, consequently, in numerous hadronic observables, so that we are now in a position to exhibit the consequences of confinement and DCSB in a wide range of hadron observables, opening the way to empirical verification of their expression in the Standard Model.

  11. Microgravity Transport Phenomena Experiment (MTPE) Overview

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.

    1999-01-01

    The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry

  12. Mathematical methods of studying physical phenomena

    NASA Astrophysics Data System (ADS)

    Man'ko, Margarita A.

    2013-03-01

    In recent decades, substantial theoretical and experimental progress was achieved in understanding the quantum nature of physical phenomena that serves as the foundation of present and future quantum technologies. Quantum correlations like the entanglement of the states of composite systems, the phenomenon of quantum discord, which captures other aspects of quantum correlations, quantum contextuality and, connected with these phenomena, uncertainty relations for conjugate variables and entropies, like Shannon and Rényi entropies, and the inequalities for spin states, like Bell inequalities, reflect the recently understood quantum properties of micro and macro systems. The mathematical methods needed to describe all quantum phenomena mentioned above were also the subject of intense studies in the end of the last, and beginning of the new, century. In this section of CAMOP 'Mathematical Methods of Studying Physical Phenomena' new results and new trends in the rapidly developing domain of quantum (and classical) physics are presented. Among the particular topics under discussion there are some reviews on the problems of dynamical invariants and their relations with symmetries of the physical systems. In fact, this is a very old problem of both classical and quantum systems, e.g. the systems of parametric oscillators with time-dependent parameters, like Ermakov systems, which have specific constants of motion depending linearly or quadratically on the oscillator positions and momenta. Such dynamical invariants play an important role in studying the dynamical Casimir effect, the essence of the effect being the creation of photons from the vacuum in a cavity with moving boundaries due to the presence of purely quantum fluctuations of the electromagnetic field in the vacuum. It is remarkable that this effect was recently observed experimentally. The other new direction in developing the mathematical approach in physics is quantum tomography that provides a new vision of

  13. Novel nuclear phenomena in quantum chromodynamics

    SciTech Connect

    Brodsky, S.J.

    1987-08-01

    Many of the key issues in understanding quantum chromodynamics involve processes in nuclear targets at intermediate energies. A range of hadronic and nuclear phenomena-exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction were discussed as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Several areas were also reviewed where there has been significant theoretical progress determining the form of hadron and nuclear wave functions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. A possible interpretation was also discussed of the large spin correlation A/sub NN/ in proton-proton scattering, and how relate this effect to an energy and angular dependence of color transparency in nuclei. 76 refs., 24 figs.

  14. The demystification of autoscopic phenomena: experimental propositions.

    PubMed

    Mohr, Christine; Blanke, Olaf

    2005-06-01

    Autoscopic phenomena (AP) are rare, illusory visual experiences during which the subject has the impression of seeing a second own body in extrapersonal space. AP consist of out-of-body experience, autoscopic hallucination, and heautoscopy. Recent neurologic reports support the role of multisensory integration deficits of body-related information and vestibular dysfunctions in AP at the temporo-parietal junction. A caveat to test the underlying neurologic and cognitive mechanisms of AP has been their rare and spontaneous occurrence. Recent evidence linked AP to mental own-body imagery engaging brain mechanisms at the temporo-parietal junction. These recent observations open a new avenue for testing AP-related cognitive mechanisms in selected clinical and normal populations. We review evidence on several clinical syndromes (psychosis, depression, anxiety, depersonalization, body dysmorphic disorder), suggesting that some of these syndromes may relate to AP-proneness, thereby leading to testable propositions for future research on body and self processing in addition to AP.

  15. Topological Spintronics: Materials, Phenomena and Devices

    NASA Astrophysics Data System (ADS)

    Samarth, Nitin

    2015-03-01

    The two-dimensional surface states of three-dimensional topological insulators such as Bi2Se3and(Bi,Sb)2Te3 possess a spin texture that can potentially be exploited for spintronics applications. We provide a perspective on the emergence of ``topological spintronics,'' demonstrating how this spin texture can be engineered using either quantum tunneling between surfaces or by breaking time-reversal symmetry. We then discuss recent experiments that show striking spintronic phenomena useful for proof-of-concept devices, including a spin-orbit torque of record efficiency at room temperature and an electrically-gated ``giant anisotropic magnetoresistance'' at low temperature. This work was carried out in collaboration with A. Richardella, S.-Y. Xu, M. Neupane, A. Mellnik, A. Kandala, J. S. Lee, D. M. Zhang, M. Z. Hasan and D. C. Ralph. We acknowledge funding from the DARPA Meso program, ONR and C-SPIN (under sponsorship of MARCO and DARPA).

  16. Coherence Phenomena in Coupled Optical Resonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2007-01-01

    Quantum coherence effects in atomic media such as electromagnetically-induced transparency and absorption, lasing without inversion, super-radiance and gain-assisted superluminality have become well-known in atomic physics. But these effects are not unique to atoms, nor are they uniquely quantum in nature, but rather are fundamental to systems of coherently coupled oscillators. In this talk I will review a variety of analogous photonic coherence phenomena that can occur in passive and active coupled optical resonators. Specifically, I will examine the evolution of the response that can occur upon the addition of a second resonator, to a single resonator that is side-coupled to a waveguide, as the coupling is increased, and discuss the conditions for slow and fast light propagation, coupled-resonator-induced transparency and absorption, lasing without gain, and gain-assisted superluminal pulse propagation. Finally, I will discuss the application of these systems to laser stabilization and gyroscopy.

  17. Electron Acceleration by Transient Ion Foreshock Phenomena

    NASA Astrophysics Data System (ADS)

    Wilson, L. B., III; Turner, D. L.

    2015-12-01

    Particle acceleration is a topic of considerable interest in space, laboratory, and astrophysical plasmas as it is a fundamental physical process to all areas of physics. Recent THEMIS [e.g., Turner et al., 2014] and Wind [e.g., Wilson et al., 2013] observations have found evidence for strong particle acceleration at macro- and meso-scale structures and/or pulsations called transient ion foreshock phenomena (TIFP). Ion acceleration has been extensively studied, but electron acceleration has received less attention. Electron acceleration can arise from fundamentally different processes than those affecting ions due to differences in their gyroradii. Electron acceleration is ubiquitous, occurring in the solar corona (e.g., solar flares), magnetic reconnection, at shocks, astrophysical plasmas, etc. We present new results analyzing the dependencies of electron acceleration on the properties of TIFP observed by the THEMIS spacecraft.

  18. Surfactant-based critical phenomena in microgravity

    NASA Technical Reports Server (NTRS)

    Kaler, Eric W.; Paulaitis, Michael E.

    1994-01-01

    The objective of this research project is to characterize by experiment and theoretically both the kinetics of phase separation and the metastable structures produced during phase separation in a microgravity environment. The particular systems we are currently studying are mixtures of water, nonionic surfactants, and compressible supercritical fluids at temperatures and pressures where the coexisting liquid phases have equal densities (isopycnic phases). In this report, we describe experiments to locate equilibrium isopycnic phases and to determine the 'local' phase behavior and critical phenomena at nearby conditions of temperature, pressure, and composition. In addition, we report the results of preliminary small angle neutron scattering (SANS) experiments to characterize microstructures that exist in these mixtures at different fluid densities.

  19. Pump instability phenomena generated by fluid forces

    NASA Technical Reports Server (NTRS)

    Gopalakrishnan, S.

    1985-01-01

    Rotor dynamic behavior of high energy centrifugal pumps is significantly affected by two types of fluid forces; one due to the hydraulic interaction of the impeller with the surrounding volute or diffuser and the other due to the effect of the wear rings. The available data on these forces is first reviewed. A simple one degree-of-freedom system containing these forces is analytically solved to exhibit the rotor dynamic effects. To illustrate the relative magnitude of these phenomena, an example of a multistage boiler feed pump is worked out. It is shown that the wear ring effects tend to suppress critical speed and postpone instability onset. But the volute-impeller forces tend to lower the critical speed and the instability onset speed. However, for typical boiler feed pumps under normal running clearances, the wear ring effects are much more significant than the destabilizing hydraulic interaction effects.

  20. Dynamic phenomena in coronal flux tubes

    NASA Technical Reports Server (NTRS)

    Mariska, J. T.; Boris, J. P.

    1981-01-01

    The study of stellar atmospheres and the determination of specific physical mechanisms, geometries, and magnetic structures by which coronae are maintained is examined. Ultraviolet and soft X-ray components observed in the radiative output of cool stars and the Sun require counterentropic temperature gradients for their explanation. The existence of a hot corona is recognized as a result of mechanical or fluid dynamic effects and the importance of the magnetic field in the heating is accepted. Magnetohydrodynamic energy release associated with the emergence of magnetic flux through the chromosphere and its dynamic readjustment in the corona are major counterentropic phenomena which are considered as primary candidates for corona heating. Systematic plows in coronal flux tubes result from asymmetric heating and systematic flows can exist without substantial chromospheric pressure differences.

  1. Reversion phenomena of Cu-Cr alloys

    NASA Technical Reports Server (NTRS)

    Nishikawa, S.; Nagata, K.; Kobayashi, S.

    1985-01-01

    Cu-Cr alloys which were given various aging and reversion treatments were investigated in terms of electrical resistivity and hardness. Transmission electron microscopy was one technique employed. Some results obtained are as follows: the increment of electrical resistivity after the reversion at a constant temperature decreases as the aging temperature rises. In a constant aging condition, the increment of electrical resistivity after the reversion increases, and the time required for a maximum reversion becomes shorter as the reversion temperature rises. The reversion phenomena can be repeated, but its amount decreases rapidly by repetition. At first, the amount of reversion increases with aging time and reaches its maximum, and then tends to decrease again. Hardness changes by the reversion are very small, but the hardness tends to soften slightly. Any changes in transmission electron micrographs by the reversion treatment cannot be detected.

  2. Microdevices enabled by rarefied flow phenomena

    NASA Astrophysics Data System (ADS)

    Alexeenko, Alina A.; Strongrich, A. D.; Cofer, A. G.; Pikus, A.; Sebastiao, I. B.; Tholeti, S. S.; Shivkumar, G.

    2016-11-01

    In this paper we review emerging applications of rarefied gas dynamics for microscale sensing, actuation, power generation and thermal management. The performance of conventional fluidic devices such as pumps, combustors and heat engines drops with the decrease of characteristic length scale due to greater viscous and heat transfer losses. However, the close coupling between non-equilibrium gas, liquid and solid-state transport and electromagnetic phenomena enables unconventional micro/nanodevices. We specifically consider three distinct examples of devices with non-equilibrium gas-phase transport based on i) very large thermal gradients; ii) increased capillary forces; iii) high electric fields - all of which are generated by scaling down device size by using nano/micromanufacturing techniques.

  3. Large Interface Simulation in Multiphase Flow Phenomena

    SciTech Connect

    Henriques, Aparicio; Coste, Pierre; Pigny, Sylvain; Magnaudet, Jacques

    2006-07-01

    An attempt to represent multiphase multi-scale flow, filling the gap between Direct Numerical Simulation (DNS) and averaged approaches, is the purpose of this paper. We present a kind of Large Interface (LI) simulation formalism obtained after a filtering process on local instantaneous conservation equations of the two-fluid model which distinguishes between small scales and large scales contributions. LI surface tension force is also taken into account. Small scale dynamics call for modelization and large scale for simulation. Joined to this formalism, a criterion to recognize LI's is developed. It is used in an interface recognition algorithm which is qualified on a sloshing case and a bubble oscillation under zero-gravity. This method is applied to a rising bubble in a pool that collapses at a free surface and to a square-base basin experiment where splashing and sloshing at the free surface are the main break-up phenomena. (authors)

  4. Lunar orbital photography of astronomical phenomena.

    NASA Technical Reports Server (NTRS)

    Mercer, R. D.; Dunkelman, L.; Ross, C. L.; Worden, A.

    1972-01-01

    This paper reports further progress on photography of faint astronomical and geophysical phenomena accomplished during the recent Apollo missions. Command module pilots have been able to photograph such astronomical objects as the solar corona, zodiacal light-corona transition region, lunar libration region, and portions of the Milky Way. The methods utilized for calibration of the film by adaptation of the High Altitude Observatory sensitometer are discussed. Kodak 2485 high-speed recording film was used in both 35-mm and 70-mm formats. The cameras used were Nikon f/1.2 55-mm focal length and Hasselblad f/2.8 80-mm focal length. Preflight and postflight calibration exposures were included on both the flight and control films, corresponding to luminances extending from the inner solar corona to as faint as 1/10 of the luminance of the light of the night sky. The photographs obtained from unique vantage points available during lunar orbit are discussed.

  5. Geometrical-numerical approach to diffraction phenomena.

    PubMed

    Bosch, S; Ferré-Borrull, J

    2001-02-15

    The calculation of diffracted fields is considered by means of a geometrical analysis of the incoming wave into semiperiodic zones in the aperture plane, followed by a numerical process for addition of the contributions corresponding to the semiperiodic zones. This general approach constitutes a novel interpretation of diffraction phenomena that permits exact evaluation of the mathematical expressions of diffraction theory and overcomes the limitations of any approximation. The method is illustrated by analysis of two important configuration in optics: the pinhole camera, for which we deduce the optimum radius for imaging, and the diffraction of a spherical converging wave through a circular aperture, from which we determine the limit of the validity of the Fraunhofer approximation (i.e., of the Airy pattern) and the influence of the obliquity factor.

  6. Single event phenomena: Testing and prediction

    NASA Technical Reports Server (NTRS)

    Kinnison, James D.

    1992-01-01

    Highly integrated microelectronic devices are often used to increase the performance of satellite systems while reducing the system power dissipation, size, and weight. However, these devices are usually more susceptible to radiation than less integrated devices. In particular, the problem of sensitivity to single event upset and latchup is greatly increased as the integration level is increased. Therefore, a method for accurately evaluating the susceptibility of new devices to single event phenomena is critical to qualifying new components for use in space systems. This evaluation includes testing devices for upset or latchup and extrapolating the results of these tests to the orbital environment. Current methods for testing devices for single event effects are reviewed, and methods for upset rate prediction, including a new technique based on Monte Carlo simulation, are presented.

  7. Pairing phenomena in strongly correlated Fermi liquids

    NASA Astrophysics Data System (ADS)

    Krotscheck, E.; Smith, R. A.; Jackson, A. D.

    1981-12-01

    The correlated-basis-function method is extended to deal with pairing phenomena in strongly correlated Fermi liquids. With a variational ansatz for the model wave function we derive the "correlated" analog of the conventional Bardeen-Cooper-Schrieffer (or Balian-Werthamer), Anderson-Brinkman-Morel theory of pairing. A suitable (and well-controlled) set of approximations brings the theory into a form identical to the conventional theories, but with the bare interaction replaced by a weak effective interaction and the bare single-particle energies replaced by an effective single-particle spectrum. As usual, liquid 3He provides a very stringent test of the theory, as both the interaction and the experimental facts are pretty clear. The variational estimates for the pairing interaction are improved by nonorthogonal perturbation theory. We find the expected enhancement of the attraction in P waves, although the restriction to effective two-body interactions appears to be insufficient to generate P-wave pairing.

  8. Teaching wave phenomena via biophysical applications

    NASA Astrophysics Data System (ADS)

    Reich, Daniel; Robbins, Mark; Leheny, Robert; Wonnell, Steven

    2014-03-01

    Over the past several years we have developed a two-semester second-year physics course sequence for students in the biosciences, tailored in part to the needs of undergraduate biophysics majors. One semester, ``Biological Physics,'' is based on the book of that name by P. Nelson. This talk will focus largely on the other semester, ``Wave Phenomena with Biophysical Applications,'' where we provide a novel introduction to the physics of waves, primarily through the study of experimental probes used in the biosciences that depend on the interaction of electromagnetic radiation with matter. Topic covered include: Fourier analysis, sound and hearing, diffraction - culminating in an analysis of x-ray fiber diffraction and its use in the determination of the structure of DNA - geometrical and physical optics, the physics of modern light microscopy, NMR and MRI. Laboratory exercises tailored to this course will also be described.

  9. Analysis of oblique hypervelocity impact phenomena

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Taylor, Roy A.

    1988-01-01

    This paper describes the results of an experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to a meteoroid or space debris environement.

  10. Meteorological phenomena in Western classical orchestral music

    NASA Astrophysics Data System (ADS)

    Williams, P. D.; Aplin, K. L.

    2012-12-01

    The creative output of composers, writers, and artists is often influenced by their surroundings. To give a literary example, it has been claimed recently that some of the characters in Oliver Twist and A Christmas Carol were based on real-life people who lived near Charles Dickens in London. Of course, an important part of what we see and hear is not only the people with whom we interact, but also our geophysical surroundings. Of all the geophysical phenomena to influence us, the weather is arguably the most significant, because we are exposed to it directly and daily. The weather was a great source of inspiration for Monet, Constable, and Turner, who are known for their scientifically accurate paintings of the skies. But to what extent does weather inspire composers? The authors of this presentation, who are atmospheric scientists by day but amateur classical musicians by night, have been contemplating this question. We have built a systematic musical database, which has allowed us to catalogue and analyze the frequencies with which weather is depicted in a sample of classical orchestral music. The depictions vary from explicit mimicry using traditional and specialized orchestral instruments, through to subtle suggestions. We have found that composers are generally influenced by their own environment in the type of weather they choose to represent. As befits the national stereotype, British composers seem disproportionately keen to depict the UK's variable weather patterns and stormy coastline. Reference: Aplin KL and Williams PD (2011) Meteorological phenomena in Western classical orchestral music. Weather, 66(11), pp 300-306. doi:10.1002/wea.765

  11. Transient Lunar Phenomena: Regularity and Reality

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin P. S.

    2009-05-01

    Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is controversial. Nonetheless, TLP data show regularities in the observations; a key question is whether this structure is imposed by processes tied to the lunar surface, or by terrestrial atmospheric or human observer effects. I interrogate an extensive catalog of TLPs to gauge how human factors determine the distribution of TLP reports. The sample is grouped according to variables which should produce differing results if determining factors involve humans, and not reflecting phenomena tied to the lunar surface. Features dependent on human factors can then be excluded. Regardless of how the sample is split, the results are similar: ~50% of reports originate from near Aristarchus, ~16% from Plato, ~6% from recent, major impacts (Copernicus, Kepler, Tycho, and Aristarchus), plus several at Grimaldi. Mare Crisium produces a robust signal in some cases (however, Crisium is too large for a "feature" as defined). TLP count consistency for these features indicates that ~80% of these may be real. Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D, and Gassendi. These reports begin almost exclusively after 1955, when TLPs became widely known and many more (and inexperienced) observers searched for TLPs. In a companion paper, we compare the spatial distribution of robust TLP sites to transient outgassing (seen by Apollo and Lunar Prospector instruments). To a high confidence, robust TLP sites and those of lunar outgassing correlate strongly, further arguing for the reality of TLPs.

  12. Oscillatory Phenomena in a Solar Network Region

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.; Tsiropoula, G.; Schwartz, P.; Heinzel, P.

    2008-09-01

    Multi-wavelength, multi-instrument observations, obtained during a coordinated observing campaign on October 2005 by the ground-based Dutch Open Telescope (DOT), and by instruments on the spacecraft Solar and Heliospheric Observatory (SoHO) and Transition Region and Coronal Explorer (TRACE), are used to study oscillatory phenomena in a solar network region. Temporal variations of the intensities and velocities in a region of the quiet Sun containing several dark mottles and in a region with several bright points defining the network boundaries (NB) are investigated with the aim of finding similarities and/or differences in the oscillatory phenomena observed in these two regions and in different spectral lines formed from the chromosphere to the transition region, as well as propagation characteristics of waves. A wavelet, phase difference and coherence analyses were performed indicating a periodicity around 5 min in all considered lines for both regions. V-V phase differences in the NB region point to an upward propagation of, most probably, acoustic waves, while in the region of mottles they indicate a non vertical propagation of waves, due to the presence of several inclined mottles along the line-of-sight. In mottles, for periods of 250-400 s the phase difference is mainly negative suggesting that propagating waves encounter a boundary and are refracted and reflected. However, limitations arising from the complex topology of the magnetic field, the formation conditions and heights of the examined spectral lines and the low spatial resolution of the space instruments influence the exact interpretation of the phase differences.

  13. TRANSIENT LUNAR PHENOMENA: REGULARITY AND REALITY

    SciTech Connect

    Crotts, Arlin P. S.

    2009-05-20

    Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is controversial. Nonetheless, TLP data show regularities in the observations; a key question is whether this structure is imposed by processes tied to the lunar surface, or by terrestrial atmospheric or human observer effects. I interrogate an extensive catalog of TLPs to gauge how human factors determine the distribution of TLP reports. The sample is grouped according to variables which should produce differing results if determining factors involve humans, and not reflecting phenomena tied to the lunar surface. Features dependent on human factors can then be excluded. Regardless of how the sample is split, the results are similar: {approx}50% of reports originate from near Aristarchus, {approx}16% from Plato, {approx}6% from recent, major impacts (Copernicus, Kepler, Tycho, and Aristarchus), plus several at Grimaldi. Mare Crisium produces a robust signal in some cases (however, Crisium is too large for a 'feature' as defined). TLP count consistency for these features indicates that {approx}80% of these may be real. Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D, and Gassendi. These reports begin almost exclusively after 1955, when TLPs became widely known and many more (and inexperienced) observers searched for TLPs. In a companion paper, we compare the spatial distribution of robust TLP sites to transient outgassing (seen by Apollo and Lunar Prospector instruments). To a high confidence, robust TLP sites and those of lunar outgassing correlate strongly, further arguing for the reality of TLPs.

  14. Nonlinear Phenomena in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.

    2008-03-01

    We present a medley of results from the last three years on nonlinear phenomena in BECs [1]. These include exact dynamics of multi-component condensates in optical lattices [2], vortices and ring solitons [3], macroscopic quantum tunneling [4], nonlinear band theory [5], and a pulsed atomic soliton laser [6]. 1. Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment, ed. P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer-Verlag, to appear, 2008) -- see L. D. Carr and Joachim Brand, e-print arXiv:0705.1139 (2007); Joachim Brand, L. D. Carr, B. P. Anderson, e-print arXiv:0705.1341 (2007). 2. R. Mark Bradley, James E. Bernard, and L. D. Carr, e-print arXiv:0711.1896 (2007). 3. G. Herring, L. D. Carr, R. Carretero-Gonzalez, P. G. Kevrekidis, D. J. Frantzeskakis, e-print arXiv:0709.2193 (2007); L. D. Carr and C. W. Clark, Phys. Rev. A v. 74, p.043613 (2006); L. D. Carr and C. W. Clark, Phys. Rev. Lett. v. 97, p.010403 (2006). 4. L. D. Carr, M. J. Holland, and B. A. Malomed, J. Phys. B: At. Mol. Opt. Phys., v.38, p.3217 (2005) 5. B. T. Seaman, L. D. Carr, and M. J. Holland, Phys. Rev. A, v. 71, p.033622 (2005). 6. L. D. Carr and J. Brand, Phys. Rev. A, v.70, p.033607 (2004); L. D. Carr and J. Brand, Phys. Rev. Lett., v.92, p.040401 (2004).

  15. Crystal clear

    NASA Astrophysics Data System (ADS)

    2012-02-01

    A semiconductor is usually opaque to any light whose photon energy is larger than the semiconductor bandgap. Nature Photonics spoke to Stephen Durbin about how to render GaAs semiconductor crystals transparent using intense X-ray pulses.

  16. Surface energies of elemental crystals

    PubMed Central

    Tran, Richard; Xu, Zihan; Radhakrishnan, Balachandran; Winston, Donald; Sun, Wenhao; Persson, Kristin A.; Ong, Shyue Ping

    2016-01-01

    The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal’s equilibrium shape. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. In this work, we present the largest database of calculated surface energies for elemental crystals to date. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. Well-known reconstruction schemes are also accounted for. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials. PMID:27622853

  17. Nucleation of Crystals in Solution

    NASA Astrophysics Data System (ADS)

    Vekilov, Peter G.

    2010-07-01

    Solution crystallization is an essential part of processes in the chemical and pharmaceutical industries and a major step in physiological and pathological phenomena. Crystallization starts with nucleation and control of nucleation is crucial for the control of the number, size, perfection, polymorphism and other characteristics of the crystalline materials. Recently, there have been significant advances in the understanding of the mechanism of nucleation of crystals in solution. The most significant of these is the two-step mechanism of nucleation, according to which the crystalline nucleus appears inside pre-existing metastable clusters of size several hundred nanometers, which consist of dense liquid and are suspended in the solution. While initially proposed for protein crystals, the applicability of this mechanism has been demonstrated for small molecule organic materials, colloids, and biominerals. This mechanism helps to explain several long-standing puzzles of crystal nucleation in solution: nucleation rates which are many orders of magnitude lower than theoretical predictions, nucleation kinetic dependencies with steady or receding parts at increasing supersaturation, the role of heterogeneous substrates for polymorph selection, the significance of the dense protein liquid, and others. More importantly, this mechanism provides powerful tools for control of the nucleation process by varying the solution thermodynamic parameters so that the volume occupied by the dense liquid shrinks or expands.

  18. Computer Modeling of Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Hashim, Rauzah

    This chapter outlines the methodologies and models which are commonly used in the simulation of liquid crystals. The approach in the simulation of liquid crystals has always been to understand the nature of the phase and to relate this to fundamental molecular features such as geometry and intermolecular forces, before important properties related to certain applications are elucidated. Hence, preceding the description of the main "molecular-based" models for liquid crystals, a general but brief outline of the nature of liquid crystals and their historical development is given. Three main model classes, namely the coarse-grained single-site lattice and Gay-Berne models and the full atomistic model will be described here where for each a brief review will be given followed by assessment of its application in describing the phase phenomena with an emphasis on understanding the molecular organization in liquid crystal phases and the prediction of their bulk properties. Variants and hybrid models derived from these classes and their applications are given.

  19. Visualization of atomic-scale phenomena in superconductors: application to FeSe

    SciTech Connect

    Choubey, Peayush; Berlijn, Tom; Kreisel, Andreas; Cao, Chao; Hirschfeld, Peter J.

    2014-10-31

    Here we propose a simple method of calculating inhomogeneous, atomic-scale phenomena in superconductors which makes use of the wave function information traditionally discarded in the construction of tight-binding models used in the Bogoliubov-de Gennes equations. The method uses symmetry- based first principles Wannier functions to visualize the effects of superconducting pairing on the distribution of electronic states over atoms within a crystal unit cell. Local symmetries lower than the global lattice symmetry can thus be exhibited as well, rendering theoretical comparisons with scanning tunneling spectroscopy data much more useful. As a simple example, we discuss the geometric dimer states observed near defects in superconducting FeSe.

  20. Interfacial phenomena in gas hydrate systems.

    PubMed

    Aman, Zachary M; Koh, Carolyn A

    2016-03-21

    Gas hydrates are crystalline inclusion compounds, where molecular cages of water trap lighter species under specific thermodynamic conditions. Hydrates play an essential role in global energy systems, as both a hinderance when formed in traditional fuel production and a substantial resource when formed by nature. In both traditional and unconventional fuel production, hydrates share interfaces with a tremendous diversity of materials, including hydrocarbons, aqueous solutions, and inorganic solids. This article presents a state-of-the-art understanding of hydrate interfacial thermodynamics and growth kinetics, and the physiochemical controls that may be exerted on both. Specific attention is paid to the molecular structure and interactions of water, guest molecules, and hetero-molecules (e.g., surfactants) near the interface. Gas hydrate nucleation and growth mechanics are also presented, based on studies using a combination of molecular modeling, vibrational spectroscopy, and X-ray and neutron diffraction. The fundamental physical and chemical knowledge and methods presented in this review may be of value in probing parallel systems of crystal growth in solid inclusion compounds, crystal growth modifiers, emulsion stabilization, and reactive particle flow in solid slurries.

  1. Pathways toward understanding Macroscopic Quantum Phenomena

    NASA Astrophysics Data System (ADS)

    Hu, B. L.; Subaşi, Y.

    2013-06-01

    Macroscopic quantum phenomena refer to quantum features in objects of 'large' sizes, systems with many components or degrees of freedom, organized in some ways where they can be identified as macroscopic objects. This emerging field is ushered in by several categories of definitive experiments in superconductivity, electromechanical systems, Bose-Einstein condensates and others. Yet this new field which is rich in open issues at the foundation of quantum and statistical physics remains little explored theoretically (with the important exception of the work of A J Leggett [1], while touched upon or implied by several groups of authors represented in this conference. Our attitude differs in that we believe in the full validity of quantum mechanics stretching from the testable micro to meso scales, with no need for the introduction of new laws of physics.) This talk summarizes our thoughts in attempting a systematic investigation into some key foundational issues of quantum macroscopic phenomena, with the goal of ultimately revealing or building a viable theoretical framework. Three major themes discussed in three intended essays are the large N expansion [2], the correlation hierarchy [3] and quantum entanglement [4]. We give a sketch of the first two themes and then discuss several key issues in the consideration of macro and quantum, namely, a) recognition that there exist many levels of structure in a composite body and only by judicious choice of an appropriate set of collective variables can one give the best description of the dynamics of a specific level of structure. Capturing the quantum features of a macroscopic object is greatly facilitated by the existence and functioning of these collective variables; b) quantum entanglement, an exclusively quantum feature [5], is known to persist to high temperatures [6] and large scales [7] under certain conditions, and may actually decrease with increased connectivity in a quantum network [8]. We use entanglement as a

  2. Living matter: the "lunar eclipse" phenomena.

    PubMed

    Korpan, Nikolai N

    2010-01-01

    The present investigations describe a unique phenomenon, namely the phenomenon of the "lunar eclipse", which has been observed and discovered by the author in living substance during the freeze-thawing processes in vivo using temperatures of various intensities and its cryosurgical response in animal experiment. Similar phenomena author has observed in nature, namely the total lunar eclipse and total solar eclipse. In this experimental study 76 animals (mongrel dogs) were investigated. A disc cryogenic probe was placed on the pancreas after the laparotomy. For cryosurgical exposure a temperature range of -40 degrees C, -80 degrees C, -120 degrees C and -180 degrees C was selected in contact with pancreas parenchyma. The freeze-thaw cycle was monitored by intraoperative ultrasound before, during and after cryosurgery. Each cryolesion was observed for one hour after thawing intraoperatively. Immediately after freezing, during the thawing process, the snow-white pancreas parenchyma, frozen hard to an ice block and resembling a full moon with a sharp demarcation line, gradually assumed a ruby-red shade and a hemispherical shape as it grew in size depend on reconstruction vascular circulation from the periphery to the center. This snow-white cryogenic lesion dissolved in the same manner in all animal tissues. The "lunar eclipse" phenomenon contributes to a fundamental understanding of the mechanisms of biological tissue damage during low temperature exposure in cryoscience and cryomedicine. Properties of the pancreas parenchyma response during the phenomenon of the "lunar eclipse" provide important insights into the mechanisms of damage and the formation of cryogenic lesion immediately after thawing in cryosurgery. Vascular changes and circulatory stagnation are commonly considered to be the main mechanism of biological tissue injury during low temperature exposure. The phenomenon of the "lunar eclipse" suggests that cryosurgery is the first surgical technique to use

  3. BPS States, Crystals, and Matrices

    DOE PAGES

    Sułkowski, Piotr

    2011-01-01

    We review free fermion, melting crystal, and matrix model representations of wall-crossing phenomena on local, toric Calabi-Yau manifolds. We consider both unrefined and refined BPS counting of closed BPS states involving D2- and D0-branes bound to a D6-brane, as well as open BPS states involving open D2-branes ending on an additional D4-brane. Appropriate limit of these constructions provides, among the others, matrix model representation of refined and unrefined topological string amplitudes.

  4. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  5. Bifurcation analysis method of nonlinear traffic phenomena

    NASA Astrophysics Data System (ADS)

    Ai, Wenhuan; Shi, Zhongke; Liu, Dawei

    2015-03-01

    A new bifurcation analysis method for analyzing and predicting the complex nonlinear traffic phenomena based on the macroscopic traffic flow model is presented in this paper. This method makes use of variable substitution to transform a traditional traffic flow model into a new model which is suitable for the stability analysis. Although the substitution seems to be simple, it can extend the range of the variable to infinity and build a relationship between the traffic congestion and the unstable system in the phase plane. So the problem of traffic flow could be converted into that of system stability. The analysis identifies the types and stabilities of the equilibrium solutions of the new model and gives the overall distribution structure of the nearby equilibrium solutions in the phase plane. Then we deduce the existence conditions of the models Hopf bifurcation and saddle-node bifurcation and find some bifurcations such as Hopf bifurcation, saddle-node bifurcation, Limit Point bifurcation of cycles and Bogdanov-Takens bifurcation. Furthermore, the Hopf bifurcation and saddle-node bifurcation are selected as the starting point of density temporal evolution and it will be helpful for improving our understanding of stop-and-go wave and local cluster effects observed in the free-way traffic.

  6. Anomalous Magnetoresistance Phenomena in Organic Semiconductors

    NASA Astrophysics Data System (ADS)

    Bergeson, Jeremy D.; Lincoln, Derek M.; Shima Edelstein, Ruth; Prigodin, Vladimir N.; Epstein, Arthur J.

    2006-03-01

    We report magnetoresistance (MR) phenomena with temperature and bias dependence in organic semiconductor thin films with either nonmagnetic or magnetic contacts through high field reaching 9T. For nonmagnetic organic thin films such as Alq3 we find a low field MR up to 15%. A similar magnetic field effect has been reported earlier^1 but, as noted, the mechanism remains unclear. We propose a model of the anomalous MR where charge transport is space-charge limited. The current is determined by the e-h recombination rate. The recombination rate is field dependent, analogous to the chemical yield for radical pairs^2. Using an organic- based magnetic semiconductor^3, V[TCNE]x, and Co as magnetic contacts, with a nonmagnetic organic semiconductor (α-6T) leads to an order-of-magnitude broader zero-centered MR peak superimposed on a spin-valve effect. Possible origins of this broader MR will be discussed. 1. Francis, et al., New J. Phys. 6 185 (2004); Frankevich, et al., Phys. Rev. B 53 4498 (1996) 2. Steiner and Ulrich, Chem. Rev. 89 51 (1989) 3. Pokhodnya, et al., Adv. Mater. 12 410 (2000); Prigodin, et al., Adv. Mater. 14 1230 (2002); Shima Edelstein, et al., Mater. Res. Soc. Symp. Proc. 871E I7.3 (2005)

  7. Highly energetic phenomena in water electrolysis.

    PubMed

    Postnikov, A V; Uvarov, I V; Lokhanin, M V; Svetovoy, V B

    2016-12-16

    Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H2 and O2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is growing between the electrodes which reaches a size of 300 μm in 50 μs. Detailed dynamics of the system is monitored by means of a vibrometer by observing a piece of silicon floating above the electrodes. The energy of a single event is estimated as 0.3 μJ and a significant part of this energy is transformed into mechanical work moving the piece. The observations are explained by the combustion of hydrogen and oxygen mixture in the initial bubble with a diameter of about 40 μm. Unusual combustion mechanism supporting spontaneous ignition at room temperature is responsible for the process. The observed effect demonstrates a principal possibility to build a microscopic internal combustion engine.

  8. Highly energetic phenomena in water electrolysis

    PubMed Central

    Postnikov, A. V.; Uvarov, I. V.; Lokhanin, M. V.; Svetovoy, V. B.

    2016-01-01

    Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H2 and O2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is growing between the electrodes which reaches a size of 300 μm in 50 μs. Detailed dynamics of the system is monitored by means of a vibrometer by observing a piece of silicon floating above the electrodes. The energy of a single event is estimated as 0.3 μJ and a significant part of this energy is transformed into mechanical work moving the piece. The observations are explained by the combustion of hydrogen and oxygen mixture in the initial bubble with a diameter of about 40 μm. Unusual combustion mechanism supporting spontaneous ignition at room temperature is responsible for the process. The observed effect demonstrates a principal possibility to build a microscopic internal combustion engine. PMID:27982103

  9. Efferent feedback can explain many hearing phenomena

    NASA Astrophysics Data System (ADS)

    Holmes, W. Harvey; Flax, Matthew R.

    2015-12-01

    The mixed mode cochlear amplifier (MMCA) model was presented at the last Mechanics of Hearing workshop [4]. The MMCA consists principally of a nonlinear feedback loop formed when an efferent-controlled outer hair cell (OHC) is combined with the cochlear mechanics and the rest of the relevant neurobiology. Essential elements of this model are efferent control of the OHC motility and a delay in the feedback to the OHC. The input to the MMCA is the passive travelling wave. In the MMCA amplification is localized where both the neural and tuned mechanical systems meet in the Organ of Corti (OoC). The simplest model based on this idea is a nonlinear delay line resonator (DLR), which is mathematically described by a nonlinear delay-differential equation (DDE). This model predicts possible Hopf bifurcations and exhibits its most interesting behaviour when operating near a bifurcation. This contribution presents some simulation results using the DLR model. These show that various observed hearing phenomena can be accounted for by this model, at least qualitatively, including compression effects, two-tone suppression and some forms of otoacoustic emissions (OAEs).

  10. Half collision resonance phenomena in molecules

    SciTech Connect

    Maximo Garcia-Sucre ); Raseev, G. ); Ross, S.C. )

    1991-01-01

    The Escuela Latinoamericana de Fisica (ELAF) is a series of meeting s that for 28 years has played an important role in research-level teaching of physics in Latin America. This book contains the proceedings of ELAF 90 which was held at the Instituto Venezolano de Investigaciones Cientificas (IVIC) in Caracas, Venezuela from July 23 to August 3, 1990, as part of the commemoration of the 30th anniversary of IVIC. In contrast to previous ELAF's that were of general scope, ELAF 90 centered on a particular subject matter: Half Collisional Resonance Phenomena in Molecules, Experimental and Theoretical Approaches. The term Half Collision'' refers to the fragmentation of a molecular system following is excitation by light. The lack of an incident fragmentation of a molecular system following is excitation by light. The lack of an incident particle (other than the photon) in the fragmentation process is what leads to the term. The purpose of this volume is to present current results in the experimental and theoretical study of half collisions and also to include pedagogical papers at an introductory or intermediate level. The contributions are grouped into several sections; light sources; ionization; dissociation-experimental; dissociation-theory; competition between ionization and dissociation; and particle-molecule collisions.

  11. Rotary kilns - transport phenomena and transport processes

    SciTech Connect

    Boateng, A.

    2008-01-15

    Rotary kilns and rotating industrial drying ovens are used for a wide variety of applications including processing raw minerals and feedstocks as well as heat-treating hazardous wastes. They are particularly critical in the manufacture of Portland cement. Their design and operation is critical to their efficient usage, which if done incorrectly can result in improperly treated materials and excessive, high fuel costs. This book treats all engineering aspects of rotary kilns, including thermal and fluid principles involved in their operation, as well as how to properly design an engineering process that uses rotary kilns. Chapter 1: The Rotary Kiln Evolution and Phenomenon Chapter 2: Basic Description of Rotary Kiln Operation Chapter 3: Freeboard Aerodynamic Phenomena Chapter 4: Granular Flows in Rotary Kilns Chapter 5: Mixing and Segregation Chapter 6: Combustion and Flame - includes section on types of fuels used in rotary kilns, coal types, ranking and analysis, petroleum coke combustion, scrap tire combustion, pulverized fuel (coal/coke) firing in kilns, pulverized fuel delivery and firing systems. Chapter 7: Freeboard Heat Transfer Chapter 8: Heat Transfer Processes in the Rotary Kiln Bed Chapter 9: Mass and Energy Balance Chapter 10: Rotary Kiln Minerals Process Applications.

  12. Phantom black holes and critical phenomena

    SciTech Connect

    Azreg-Aïnou, Mustapha; Marques, Glauber T.

    2014-07-01

    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.

  13. Ultrashort Phenomena in Biochemistry and Biological Signaling

    NASA Astrophysics Data System (ADS)

    Splinter, Robert

    2014-11-01

    In biological phenomena there are indications that within the long pulse-length of the action potential on millisecond scale, there is additional ultrashort perturbation encoding that provides the brain with detailed information about the origin (location) and physiological characteristics. The objective is to identify the mechanism-of-action providing the potential for encoding in biological signal propagation. The actual molecular processes involved in the initiation of the action potential have been identified to be in the femtosecond and pico-second scale. The depolarization process of the cellular membrane itself, leading to the onset of the actionpotential that is transmitted to the brain, however is in the millisecond timeframe. One example of the femtosecond chemical interaction is the photoresponse of bacteriorhodopsin. No clear indication for the spatial encoding has so far been verified. Further research will be required on a cellular signal analysis level to confirm or deny the spatial and physiological encoding in the signal wave-trains of intercellular communications and sensory stimuli. The pathological encoding process for cardiac depolarization is however very pronounced and validated, however this electro-chemical process is in the millisecond amplitude and frequency modulation spectrum.

  14. New theoretical treatment of ion resonance phenomena.

    PubMed

    Vincze, G; Szasz, A; Liboff, A R

    2008-07-01

    Despite experimental evidence supporting ICR-like interactions in biological systems, to date there is no reasonable theoretical explanation for this phenomenon. The parametric resonance approach introduced by Lednev has enjoyed limited success in predicting the response as a function of the ratio of AC magnetic intensity to that of the DC field, explaining the results in terms of magnetically induced changes in the transition probability of calcium binding states. In the present work, we derive an expression for the velocity of a damped ion with arbitrary q/m under the influence of the Lorentz force. Series solutions to the differential equations reveal transient responses as well as resonance-like terms. One fascinating result is that the expressions for ionic drift velocity include a somewhat similar Bessel function dependence as was previously obtained for the transition probability in parametric resonance. However, in the present work, not only is there an explicit effect due to damping, but the previous Bessel dependence now occurs as a subset of a more general solution, including not only the magnetic field AC/DC ratio as an independent variable, but also the ratio of the cyclotronic frequency Omega to the applied AC frequency omega. In effect, this removes the necessity to explain the ICR interaction as stemming from ion-protein binding sites. We hypothesize that the selectively enhanced drift velocity predicted in this model can explain ICR-like phenomena as resulting from increased interaction probabilities in the vicinity of ion channel gates.

  15. Two-Stage Modelling Of Random Phenomena

    NASA Astrophysics Data System (ADS)

    Barańska, Anna

    2015-12-01

    The main objective of this publication was to present a two-stage algorithm of modelling random phenomena, based on multidimensional function modelling, on the example of modelling the real estate market for the purpose of real estate valuation and estimation of model parameters of foundations vertical displacements. The first stage of the presented algorithm includes a selection of a suitable form of the function model. In the classical algorithms, based on function modelling, prediction of the dependent variable is its value obtained directly from the model. The better the model reflects a relationship between the independent variables and their effect on the dependent variable, the more reliable is the model value. In this paper, an algorithm has been proposed which comprises adjustment of the value obtained from the model with a random correction determined from the residuals of the model for these cases which, in a separate analysis, were considered to be the most similar to the object for which we want to model the dependent variable. The effect of applying the developed quantitative procedures for calculating the corrections and qualitative methods to assess the similarity on the final outcome of the prediction and its accuracy, was examined by statistical methods, mainly using appropriate parametric tests of significance. The idea of the presented algorithm has been designed so as to approximate the value of the dependent variable of the studied phenomenon to its value in reality and, at the same time, to have it "smoothed out" by a well fitted modelling function.

  16. Further shock tunnel studies of scramjet phenomena

    NASA Technical Reports Server (NTRS)

    Morgan, R. G.; Paull, A.; Morris, N. A.; Stalker, R. J.

    1986-01-01

    Scramjet phenomena were studied using the shock tunnel T3 at the Australian National University. Simple two dimensional models were used with a combination of wall and central injectors. Silane as an additive to hydrogen fuel was studied over a range of temperatures and pressures to evaluate its effect as an ignition aid. The film cooling effect of surface injected hydrogen was measured over a wide range of equivalence. Heat transfer measurements without injection were repeated to confirm previous indications of heating rates lower than simple flat plate predictions for laminar boundary layers in equilibrium flow. The previous results were reproduced and the discrepancies are discussed in terms of the model geometry and departures of the flow from equilibrium. In the thrust producing mode, attempts were made to increase specific impulse with wall injection. Some preliminary tests were also performed on shock induced ignition, to investigate the possibility in flight of injecting fuel upstream of the combustion chamber, where it could mix but not burn.

  17. Bulk Rashba Semiconductors and Related Quantum Phenomena.

    PubMed

    Bahramy, Mohammad Saeed; Ogawa, Naoki

    2017-03-29

    Bithmuth tellurohalides BiTeX (X = Cl, Br and I) are model examples of bulk Rashba semiconductors, exhibiting a giant Rashba-type spin splitting among their both valence and conduction bands. Extensive spectroscopic and transport experiments combined with the state-of-the-art first-principles calculations have revealed many unique quantum phenomena emerging from the bulk Rashba effect in these systems. The novel features such as the exotic inter- and intra-band optical transitions, enhanced magneto-optical response, divergent orbital dia-/para-magnetic susceptibility and helical spin textures with a nontrivial Berry's phase in the momentum space are among the salient discoveries, all arising from this effect. Also, it is theoretically proposed and indications have been experimentally reported that bulk Rashba semiconductors such as BiTeI have the capability of becoming a topological insulator under the application of a hydrostatic pressure. Here, we overview these studies and show that BiTeX are an ideal platform to explore the next aspects of quantum matter, which could ultimately be utilized to create spintronic devices with novel functionalities.

  18. Fingering phenomena during grain-grain displacement

    NASA Astrophysics Data System (ADS)

    Mello, Nathália M. P.; Paiva, Humberto A.; Combe, G.; Atman, A. P. F.

    2017-04-01

    Spontaneous formation of fingered patterns during the displacement of dense granular assemblies was experimentally reported few years ago, in a radial Hele-Shaw cell. Here, by means of discrete element simulations, we have recovered the experimental findings and extended the original study to explore the control parameters space. In particular, using assemblies of grains with different geometries (monodisperse, bidisperse, or polydisperse), we measured the macroscopic stress tensor in the samples in order to confirm some conjectures proposed in analogy with Saffman-Taylor viscous fingering phenomena for immiscible fluids. Considering an axial setup which allows to control the discharge of grains and to follow the trajectory and the pressure gradient along the displacing interface, we have applied the Darcy law for laminar flow in fluids in order to measure an "effective viscosity" for each assembly combination, in an attempt to mimic variation of the viscosity ratio between the injected/displaced fluids in the Saffman-Taylor experiment. The results corroborate the analogy with the viscous fluids displacement, with the bidisperse assembly corresponding to the less viscous geometry. But, differently to fluid case, granular fingers only develop for a specific combination of displaced/injected geometries, and we have demonstrated that it is always related with the formation of a force chain network along the finger direction.

  19. Recognizing hesitation phenomena in continuous, spontaneous speech

    NASA Astrophysics Data System (ADS)

    Oshaughnessy, Douglas

    Spontaneous speech differs from read speech in speaking rate and hesitation. In natural, spontaneous speech, people often start talking and then think along the way; at times, this causes the speech to have hesitation pauses (both filled and unfilled) and restarts. Results are reported on all types of pauses in a widely-used speech database, for both hesitation pauses and semi-intentional pauses. A distinction is made between grammatical pauses (at major syntactic boundaries) and ungrammatical ones. Different types of unfilled pauses cannot be reliably separated based on silence duration, although grammatical pauses tend to be longer. In the prepausal word before ungrammatical pauses, there were few continuation rises in pitch, whereas 80 percent of the grammatical pauses were accompanied by a prior fundamental frequency rise of 10-40 kHz. Identifying the syntactic function of such hesitation phenomena can improve recognition performance by eliminating from consideration some of the hypotheses proposed by an acoustic recognizer. Results presented allow simple identification of filled pauses (such as uhh, umm) and their syntactic function.

  20. Quantification of statistical phenomena in turbulent dispersions

    NASA Astrophysics Data System (ADS)

    Yates, Matthew; Hann, David; Hewakandamby, Buddhika

    2015-11-01

    Understanding of turbulent dispersions is of great importance for environmental and industrial applications. This includes developing a greater understanding of particle movement in atmospheric flows, and providing data that can be used to validate CFD models aimed at producing more accurate simulations of dispersed turbulent flows, aiding design of many industrial components. Statistical phenomena in turbulent dispersions were investigated using Particle Image Velocimetry. Experiments were carried out in a two dimensional channel over a Reynolds number range of 10000-30000, using water and 500 micron hydrogel particles. Particles were injected at the channel entrance, and dispersion properties were characterised at different distances downstream from the injection point. Probability density functions were compiled for the velocity components of the hydrogels for differing flow conditions. Higher order PDFs were constructed to investigate the behaviour of particle pairs. Dispersed phase data was also used to investigate the mechanics of collisions between hydrogel particles, allowing for calculation of the co-efficient of restitution. PIV algorithms were used to create velocity maps for the continuous phase for varying dispersed phase fractions. Thanks to support of Chevron grant as part of TMF consortium.

  1. Highly energetic phenomena in water electrolysis

    NASA Astrophysics Data System (ADS)

    Postnikov, A. V.; Uvarov, I. V.; Lokhanin, M. V.; Svetovoy, V. B.

    2016-12-01

    Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H2 and O2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is growing between the electrodes which reaches a size of 300 μm in 50 μs. Detailed dynamics of the system is monitored by means of a vibrometer by observing a piece of silicon floating above the electrodes. The energy of a single event is estimated as 0.3 μJ and a significant part of this energy is transformed into mechanical work moving the piece. The observations are explained by the combustion of hydrogen and oxygen mixture in the initial bubble with a diameter of about 40 μm. Unusual combustion mechanism supporting spontaneous ignition at room temperature is responsible for the process. The observed effect demonstrates a principal possibility to build a microscopic internal combustion engine.

  2. Observations of dynamical phenomena in sunspots

    NASA Technical Reports Server (NTRS)

    Nye, A. H.; Cram, L. E.; Beckers, J. M.; Thomas, J. H.

    1981-01-01

    A preliminary report of the results of one observing run based on data from one spectral line, the photospheric magnetic line Fe 6303, is presented as part of a series of observations of dynamical phenomena in sunspots using photographic spectra with the SPO vacuum tower telescope and echelle spectrograph. The ejection of a magnetic feature from the outer edge of the penumbra was observed. The initial total field strength of the feature was about 1000 gauss, which appeared to decrease as the feature moved away from the sunspot. The proper motion was about 2 km/s, and the velocity field measured in the V profile showed a downflow of 400 m/s on the spotward side of the moving magnetic feature. Umbral oscillations at the photospheric level with a herringbone structure characteristic of horizontally propagating waves, suggesting some overtone mode of membrane oscillation in the umbra, were seen. The peak amplitude of the oscillation was about 200 m/s, and the mean power spectrum had several clear peaks.

  3. Numerical analysis and modeling of atmospheric phenomena

    NASA Technical Reports Server (NTRS)

    Stone, Peter H.

    1994-01-01

    For the past 22 years Grant NGR 22-009-727 has been supporting research in the Center for Meteorology and Physical Oceanography (and its predecessors) in a wide variety of diagnostic and modeling studies of atmospheric and ocean phenomena. Professor Jule Charney was the initial Principal Investigator. Professor Peter Stone joined him as co-Principal Investigator in 1975 and became the sole Principal Investigator in 1981. During its lifetime the Grant has supported in whole or in part 11 Master's theses, 14 Ph.D. theses, and 45 papers published in refereed scientific journals. All of these theses and papers (with bibliographic references) are listed below. All but one of the theses were used to fulfill the requirements for MIT (Massachusetts Institute of Technology) degrees and are available from the MIT libraries. The one exception is F. Chen's Ph.D. thesis which was for a Harvard degree and is available from the Harvard libraries. In addition to the work described in the citations listed below, the Grant has supported Research Assistant Amy Solomon during the past two years to carry out a study of how baroclinic adjustment is affected by vertical resolution, vertical temperature structure, and dissipation. Ms. Solomon plans to use this project for her Ph.D. thesis. Support for this project will continue under NASA Grant NAG 5-2490, 'The Factors Controlling Poleward Heat Transport in Climate Models.'

  4. The study of single crystals for space processing and the effect of zero gravity

    NASA Technical Reports Server (NTRS)

    Lal, R. B.

    1975-01-01

    A study was undertaken to analyze different growth techniques affected by a space environment. Literature on crystal growth from melt, vapor phase and float zone was reviewed and the physical phenomena important for crystal growth in zero-gravity environment was analyzed. Recommendations for potential areas of crystal growth feasible for space missions are presented and a bibliography of articles in the area of crystal growth in general is listed.

  5. The Role of Family Phenomena in Posttraumatic Stress in Youth

    PubMed Central

    Deatrick, Janet A.

    2010-01-01

    Topic Youth face trauma that can cause posttraumatic stress (PTS). Purpose 1). To identify the family phenomena used in youth PTS research; and 2). Critically examine the research findings regarding the relationship between family phenomena and youth PTS. Sources Systematic literature review in PsycInfo, PILOTS, CINAHL, and MEDLINE. Twenty-six empirical articles met inclusion criteria. Conclusion Measurement of family phenomena included family functioning, support, environment, expressiveness, relationships, cohesion, communication, satisfaction, life events related to family, parental style of influence, and parental bonding. Few studies gave clear conceptualization of family or family phenomena. Empirical findings from the 26 studies indicate inconsistent empirical relationships between family phenomena and youth PTS, though a majority of the prospective studies support a relationship between family phenomena and youth PTS. Future directions for leadership by psychiatric nurses in this area of research and practice are recommended. PMID:21344778

  6. Natural phenomena hazards, Hanford Site, south central Washington

    SciTech Connect

    Tallman, A.M.

    1996-04-16

    This document presents the natural phenomena hazard (NPH) loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, at the Hanford Site in south-central Washington State. The purpose of this document is twofold: (1) summarize the NPH that are important to the design and evaluation of structures, systems, and components at the Hanford Site; (2) develop the appropriate natural phenomena loads for use in the implementation of DOE Order 5480.28. The supporting standards, DOE-STD-1020-94, Natural Phenomena Hazards Design and Evaluation Criteria for Department of Energy Facilities (DOE 1994a); DOE-STD-1022-94, Natural Phenomena Hazards Site Characteristics Criteria (DOE 1994b); and DOE-STD-1023-95, Natural Phenomena Hazards Assessment Criteria (DOE 1995) are the basis for developing the NPH loads.

  7. Inverse Analysis of Cavitation Impact Phenomena on Structures

    DTIC Science & Technology

    2007-07-02

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--07-9051 Inverse Analysis of Cavitation Impact Phenomena on Structures July 2, 2007...ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Inverse Analysis of Cavitation Impact Phenomena on Structures S.G. Lambrakos and N.E...signature analysis A general methodology is presented for in situ detection of cavitation impact phenomena on structures based on inverse analysis of

  8. SYMMETRICAL LASER CRYSTALS.

    DTIC Science & Technology

    CRYSTAL GROWTH , SYMMETRY(CRYSTALLOGRAPHY), LASERS, SYNTHESIS, FERROELECTRIC CRYSTALS , FLUORESCENCE, IMPURITIES, BARIUM COMPOUNDS, ZIRCONATES...STRONTIUM COMPOUNDS, TITANATES, STANNATES, SAMARIUM, MANGANESE, REFRACTORY MATERIALS, OXIDES, SINGLE CRYSTALS .

  9. Programmed death phenomena: from organelle to organism.

    PubMed

    Skulachev, Vladimir P

    2002-04-01

    Programmed death phenomena appear to be inherent not only in living cells (apoptosis), but also in subcellular organelles (e.g., self-elimination of mitochondria, called mitoptosis), organs (organoptosis), and even whole organisms (phenoptosis). In all these cases, the "Samurai law of biology"--it is better to die than to be wrong--seems to be operative. The operation of this law helps complicated living systems avoid the risk of ruin when a system of lower hierarchic position makes a significant mistake. Thus, mitoptosis purifies a cell from damaged and hence unwanted mitochondria; apoptosis purifies a tissue from unwanted cells; and phenoptosis purifies a community from unwanted individuals. Defense against reactive oxygen species (ROS) is probably one of the primary evolutionary functions of programmed death mechanisms. So far, it seems that ROS play a key role in the mito-, apo-, organo-, and phenoptoses, which is consistent with Harman's theory of aging. Here a concept is described that tries to unite Weismann's hypothesis of aging as an adaptive programmed death mechanism and the generally accepted alternative point of view that considers aging as an inevitable result of accumulation in an organism of occasional injuries. It is suggested that injury accumulation is monitored by a system(s) actuating a phenoptotic death program when the number of injuries reaches some critical level. The system(s) in question are organized in such a way that the lethal case appears to be a result of phenoptosis long before the occasional injuries make impossible the functioning of the organism. It is stressed that for humans these cruel regulations look like an atavism that, if overcome, might dramatically prolong the human life span.

  10. CFD Analysis of Core Bypass Phenomena

    SciTech Connect

    Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

    2010-03-01

    The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the sector grid can be set as a symmetry boundary

  11. CFD Analysis of Core Bypass Phenomena

    SciTech Connect

    Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz

    2009-11-01

    The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the one-twelfth grid can be set as a symmetry boundary

  12. Modeling diffusion-governed solidification of ternary alloys - Part 2: Macroscopic transport phenomena and macrosegregation.

    PubMed

    Wu, M; Li, J; Ludwig, A; Kharicha, A

    2014-09-01

    Part 1 of this two-part investigation presented a multiphase solidification model incorporating the finite diffusion kinetics and ternary phase diagram with the macroscopic transport phenomena (Wu et al., 2013). In Part 2, the importance of proper treatment of the finite diffusion kinetics in the calculation of macrosegregation is addressed. Calculations for a two-dimensional (2D) square casting (50 × 50 mm(2)) of Fe-0.45 wt.%C-1.06 wt.%Mn considering thermo-solutal convection and crystal sedimentation are performed. The modeling result indicates that the infinite liquid mixing kinetics as assumed by classical models (e.g., the Gulliver-Scheil or lever rule), which cannot properly consider the solute enrichment of the interdendritic or inter-granular melt at the early stage of solidification, might lead to an erroneous estimation of the macrosegregation. To confirm this statement, further theoretical and experimental evaluations are desired. The pattern and intensity of the flow and crystal sedimentation are dependent on the crystal morphologies (columnar or equiaxed); hence, the potential error of the calculated macrosegregation caused by the assumed growth kinetics depends on the crystal morphology. Finally, an illustrative simulation of an engineering 2.45-ton steel ingot is performed, and the results are compared with experimental results. This example demonstrates the model applicability for engineering castings regarding both the calculation efficiency and functionality.

  13. Crystal growth in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Kroes, Roger L. (Inventor); Reiss, Donald A. (Inventor); Lehoczky, Sandor L. (Inventor)

    1992-01-01

    Gravitational phenomena, including convection, sedimentation, and interactions of materials with their containers all affect the crystal growth process. If they are not taken into consideration they can have adverse effects on the quantity and quality of crystals produced. As a practical matter, convection, and sedimentation can be completely eliminated only under conditions of low gravity attained during orbital flight. There is, then, an advantage to effecting crystallization in space. In the absence of convection in a microgravity environment cooling proceeds by thermal diffusion from the walls to the center of the solution chamber. This renders control of nucleation difficult. Accordingly, there is a need for a new improved nucleation process in space. Crystals are nucleated by creating a small localized region of high relative supersaturation in a host solution at a lower degree of supersaturation.

  14. Neutron detection with single crystal organic scintillators

    SciTech Connect

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  15. Formation of a crystal nucleus from liquid

    PubMed Central

    Kawasaki, Takeshi; Tanaka, Hajime

    2010-01-01

    Crystallization is one of the most fundamental nonequilibrium phenomena universal to a variety of materials. It has so far been assumed that a supercooled liquid is in a “homogeneous disordered state” before crystallization. Contrary to this common belief, we reveal that a supercooled colloidal liquid is actually not homogeneous, but has transient medium-range structural order. We find that nucleation preferentially takes place in regions of high structural order via wetting effects, which reduce the crystal–liquid interfacial energy significantly and thus promotes crystal nucleation. This novel scenario provides a clue to solving a long-standing mystery concerning a large discrepancy between the rigorous numerical estimation of the nucleation rate on the basis of the classical nucleation theory and the experimentally observed ones. Our finding may shed light not only on the mechanism of crystal nucleation, but also on the fundamental nature of a supercooled liquid state. PMID:20663951

  16. Therapeutic Crystals

    ERIC Educational Resources Information Center

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  17. Comparing Crystals

    ERIC Educational Resources Information Center

    Sharp, Janet; Hoiberg, Karen; Chumbley, Scott

    2003-01-01

    This standard lesson on identifying salt and sugar crystals expands into an opportunity for students to develop their observation, questioning, and modeling skills. Although sugar and salt may look similar, students discovered that they looked very different under a magnifying glass and behaved differently when dissolved in water. In addition,…

  18. Optical Crystals

    ERIC Educational Resources Information Center

    Bergsten, Ronald

    1974-01-01

    Discusses the production and structure of a sequence of optical crystals which can serve as one-, two-, and three-dimensional diffraction plates to illustrate diffraction patterns by using light rather than x-rays or particles. Applications to qualitative presentations of Laue theory at the secondary and college levels are recommended. (CC)

  19. Crystal growth of device quality GaAs in space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.

    1984-01-01

    The crystal growth, device processing and device related properties and phenomena of GaAs are investigated. Our GaAs research evolves about these key thrust areas. The overall program combines: (1) studies of crystal growth on novel approaches to engineering of semiconductor materials (i.e., GaAs and related compounds); (2) investigation and correlation of materials properties and electronic characteristics on a macro- and microscale; (3) investigation of electronic properties and phenomena controlling device applications and device performance. The ground based program is developed which would insure successful experimentation with and eventually processing of GaAs in a near zero gravity environment.

  20. EPA se mueve hacia la prohibición de desengrasantes en aerosol y quitamanchas para lavado en seco como una de las primeras acciones reglamentarias conforme a la ley reformada de sustancias químicas

    EPA Pesticide Factsheets

    Comunicado de prensa de EPA: EPA se mueve hacia la prohibición de desengrasantes en aerosol y quitamanchas para lavado en seco como una de las primeras acciones reglamentarias conforme a la ley reformada de sustancias químicas

  1. The phenomenology of life phenomena--in a nursing context.

    PubMed

    Delmar, Charlotte

    2006-10-01

    The purpose of this article is to describe and develop knowledge about life phenomena in a life-philosophical and nursing context. Knowledge about life phenomena is part of a care-ethical understanding with a focus on relations. Life phenomena are to be understood as a generalized label for the various phenomena which are given with human existence. The Danish life philosophical tradition with the perspective of life as experienced has something to say in relation to a further refinement of the phenomenology of life phenomena. The refinement will be described as an ethical and existential understanding of the phenomena of nursing. The first part of the article takes a philosophical approach to the phenomenology of life phenomena. It attempts to locate life phenomena in relation to, respectively, needs, senses, and feelings. In order to maintain an overview, the attempt is made to separate needs, senses, and feelings, although in real life these are closely interwoven. The article also describes philosophy and life phenomena in relation to nursing as an empirical field. In nursing there is a risk that life phenomena become invisible to those whose task is to help the ill person adjust to a new life situation. For the nurse, it will be a continuing task, never completed, to develop a sensory-based, situation-determined attention to the patient. And the nurse must be continually aware of whether mere 'need-oriented' nursing is controlling her professional actions as a nurse. Taking a point of departure in the nurse's sensory, situationally determined attention, the last part of the article focuses on needs, senses, and feelings in connection with the nurse being able to direct her attention to the patient's life phenomena.

  2. Structural phenomena in hydrogel-drug systems

    NASA Astrophysics Data System (ADS)

    Shekunov, B. Yu; Taylor, P.; Grossmann, J. G.

    1999-03-01

    Crystallization and structural transition in a cross-linked poly(ethylene oxide) 4000 (PEO) polymer were investigated as functions of water content and concentration of model drugs (acetaminophen and caffeine) using small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) techniques. In the hydrated state (300 wt% of water), gel retains an ordering with characteristic spacing of 80 Å. With a water concentration of about 20%, this structure undergoes transition into lamellae with long spacing of 200 Å and then into semi-crystalline polymer matrix when water content is below 5%. This transition is associated with different type of phase separations, first, between crystalline and amorphous PEO domains in the dry polymer and, second, between water and hydrophobic cross-linked regions in the swollen gel. Because of a specific hydrogen bonding, acetaminophen forms a molecular complex with the PEO, a drug concentration as small as 1% resulting in a significant increase of the long spacing and decrease of crystallinity of the polymer. Caffeine precipitates in the form of crystalline particles and also reduces the crystallinity of the polymer matrix.

  3. Magnetoresistive phenomena in nanoscale magnetic systems

    NASA Astrophysics Data System (ADS)

    Burton, John D.

    Nanomagnetic materials are playing an increasingly important role in modern technologies. A particular area of interest involves the interplay between magnetism and electric transport, i.e. magnetoresistive properties. Future generations of field sensors and memory elements will have to be on a length scale of a few nanometers or smaller. Magnetoresistive properties of such nanoscale objects exhibit novel features due to reduced dimensionality, complex surfaces and interfaces, and quantum effects. In this dissertation theoretical aspects of three such nanoscale magnetoresistive phenomena are discussed. Very narrow magnetic domain walls can strongly scatter electrons leading to an increased resistance. Specifically, this dissertation will cover the newly predicted effect of magnetic moment softening in magnetic nanocontacts or nanowires. Atomically thin domain walls in Ni exhibit a reduction, or softening, of the local magnetic moments due to the noncollinearity of the magnetization. This effect leads to a strong enhancement of the resistance of a domain wall. Magnetic tunnel junctions (MTJs) consist of two ferromagnetic electrodes separated by a thin layer of insulating material through which current can be carried by electron tunneling. The resistance of an MTJ depends on the relative orientation of the magnetization of the two ferromagnetic layers, an effect known as tunneling magnetoresistance (TMR). A first-principles analysis of CoFeB|MgO|CoFeB MTJs will be presented. Calculations reveal that it is energetically favorable for interstitial boron atoms to reside at the interface between the electrode and MgO tunneling barrier, which can be detrimental to the TMR effect. Anisotropic magnetoresistance (AMR) is the change in resistance of a ferromagnetic system as the orientation of the magnetization is altered. In this dissertation, the focus will be on AMR in the tunneling regime. Specifically we will present new theoretical results on tunneling AMR (TAMR) in two

  4. Saving the Phenomena in Medieval Astronomy

    NASA Astrophysics Data System (ADS)

    Seeskin, K.

    2011-06-01

    Aristotle's theory of motion is based on two principles: (1) all motion to either from the midpoint of the Earth, toward it, or around it, and (2) circular motion must proceed around an immovable point. On this view, the heavenly bodies are individual points of light carried around by a series of concentric spheres rotating at a constant pace around the midpoint of the Earth. But even in Aristotle's day, it was known that this theory had a great deal of difficulty accounting for planetary motion. Ptolemy's alternative was to introduce epicycles and eccentric orbits, thus denying Aristotle's view of natural motion. There was no doubt that Ptolemy's predictions were far better than Aristotle's. But for the medievals, Aristotle's theory made better intuitive sense. Moreover, Ptolemy's theory raised the question of how one sphere could pass through another. What to do? The solution of Moses Maimonides (1138-1204) was to say that it is not the job of the astronomer to tell us how things actually are but merely to propose a series of hypotheses that allow us to explain the relevant data. This view had obvious theological implications. If astronomy could explain planetary motion in an acceptable way, there was reason to believe that the order or structure of the heavens is what it is by necessity. This suggests that God did not exercise any degree of choice in making it that way. But if astronomy cannot explain planetary motion, the most reasonable explanation is that we are dealing with contingent phenomena rather than necessary ones. If there is contingency, there is reason to think God did exercise a degree of choice in making the heavens the way they are. A God who exercises choice is much closer to the God of Scripture. Although Galileo changed all of this, and paved the way for a vastly different view of astronomy, the answer to one set of questions raises a whole different set. In short, the heavenly motion still poses ultimate questions about God, existence, and

  5. Investigations of Induced Charge Electrokinetic Phenomena

    NASA Astrophysics Data System (ADS)

    Pascall, Andrew James

    Recent developments in microfluidics have highlighted the importance of efficiently transporting fluids at the micron scale. This has lead to a resurgence of interest in utilizing electrokinetic phenomena, which scale favorably with the small channel dimensions encountered in microfluidics, to drive fluid flows. This dissertation focuses on induced charge electro-osmosis (ICEO), a nonlinear electrokinetic effect in which an applied electric field both induces and drives a layer of charged fluid near an electrically conductive surface. ICEO has been shown to produce time-averaged flows with AC electric fields and may provide an on-chip means of generating high pressure flows with low applied voltages. Experimental studies of ICEO have shown that standard theories generally overpredict the observed slip velocity, frequently by orders of magnitude. This discrepancy could be explained by the presence of a thin coating of an adventitious dielectric over the conductive surface. In this work, I develop a modified theory of ICEO that incorporates the effects of a dielectric coating and its surface chemistry, both of which act to decrease the slip velocity relative to a clean metal. This theory shows that a layer of dielectric contaminant of only nanometer thickness can lead to significantly suppressed ICEO flows. In order to test this theory, I developed a novel experimental apparatus, the details of which are presented herein, that allows for the observation of ICEO flows over planar surfaces coated with dielectrics of controlled physical properties. Data for over 8000 combinations of parameters over both an oxide dielectric and alkanethiol self-assembled monolayer show unprecedented quantitative agreement with this modified theory. The goal for engineering practical microfluidic devices is to generate the fastest flows possible for a given set of conditions. I end the dissertation with a discussion of how to generate flows that are orders of magnitude faster than those

  6. Raman scattering study of glass crystallization kinetics

    NASA Astrophysics Data System (ADS)

    Balkanski, M.; Haro, E.; Espinosa, G. P.; Phillips, J. C.

    1984-08-01

    Laser induced glass-crystalline transition is studied by light scattering. Three significant effects are observed depending on the incident laser energy density: (i) Spectral band narrowing indicating cluster enlargement constitutes a precursor effect, (ii) an intensity increase effect indicates a rapid rise of the density of clusters attaining microcrystalline size and (iii) a dynamical reversal effect indicative of glass-crystalline instability. Cluster volume and crystallization appear as separate but related threshold phenomena.

  7. Crystal growth of device quality GaAs in space

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.

    1983-01-01

    GaAs device technology has recently reached a new phase of rapid advancement, made possible by the improvement of the quality of GaAs bulk crystals. At the same time, the transition to the next generation of GaAs integrated circuits and optoelectronic systems for commercial and government applications hinges on new quantum steps in three interrelated areas: crystal growth, device processing and device-related properties and phenomena. Special emphasis is placed on the establishment of quantitative relationships among crystal growth parameters-material properties-electronic properties and device applications. The overall program combines studies of crystal growth on novel approaches to engineering of semiconductor material (i.e., GaAs and related compounds); investigation and correlation of materials properties and electronic characteristics on a macro- and microscale; and investigation of electronic properties and phenomena controlling device applications and device performance.

  8. Conceptual Framework to Enable Early Warning of Relevant Phenomena (Emerging Phenomena and Big Data)

    SciTech Connect

    Schlicher, Bob G; Abercrombie, Robert K; Hively, Lee M

    2013-01-01

    Graphs are commonly used to represent natural and man-made dynamic systems such as food webs, economic and social networks, gene regulation, and the internet. We describe a conceptual framework to enable early warning of relevant phenomena that is based on an artificial time-based, evolving network graph that can give rise to one or more recognizable structures. We propose to quantify the dynamics using the method of delays through Takens Theorem to produce another graph we call the Phase Graph. The Phase Graph enables us to quantify changes of the system that form a topology in phase space. Our proposed method is unique because it is based on dynamic system analysis that incorporates Takens Theorem, Graph Theory, and Franzosi-Pettini (F-P) theorem about topology and phase transitions. The F-P Theorem states that the necessary condition for phase transition is a change in the topology. By detecting a change in the topology that we represent as a set of M-order Phase Graphs, we conclude a corresponding change in the phase of the system. The onset of this phase change enables early warning of emerging relevant phenomena.

  9. Crystallization Physics in Biomacromolecular Systems

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    2003-01-01

    The crystals are built of molecules of protein, nucleic acid and their complexes, like viruses, approx. 5x10(exp 3)+ 3x10(exp 6) Da in weight and 2 + 20 nm in effective diameter. This size strongly exceeds action range of molecular forces and makes a big difference with inorganic crystals. Intermolecular contacts form patches on the biomacromolecular surface. Each patch may occupy only a small percent of the whole surface and vary from polymorph to polymorph of the same protein. Thus, under different conditions (pH, solution chemistry, temperature, any area on the macromolecular surface may form a contact. The crystal Young moduli, E approx. equals 0.1 + 0.5 GPa are more than 10 times lower than that of inorganics and the biomolecules themselves. Water within biocrystals (30-70%) is unable to flow unless typical deformation time is longer than approx. 10(exp -5)s. This explains the discrepancy between light scattering and static measurements of E. Nucleation and Growth requires typically concentrations exceeding the equilibrium ones up to 100 times - because of the new size scale results in 10 - 10(exp 3) times lower kinetic coefficients than that needed for inorganic solution growth. All phenomena observed in the latter occur with protein crystallization and are even better studied by AFM. Crystals are typically facetted. Among unexpected findings of general significance are - net molecular exchange flux at kinks is much lower than that expected from supersaturation, steps with low (< approx. 10(exp -2)) kink density at steps follow Gibbs-Thomson law only at very low supersaturations, step segment growth rate may be independent of step energy. Crystal perfection is a must of biocrystallization to achieve the major goal to find 3-D atomic structure of biomacromolecules by x-ray diffraction. Poor diffraction resolution (> 3Angstrom) makes crystallization a bottleneck for structural biology. All defects typical of small molecule crystals are found in biocrystals, but

  10. Global Phenomena from Local Rules: Peer-to-Peer Networks and Crystal Steps

    DTIC Science & Technology

    2007-01-01

    participating in these networks. We explore the use of supervised machine learning to identify peer -to- peer hosts, without using application-specific informa...We then give a detailed introduction to distributed hash tables, which are decentralized but structured peer -to- peer systems. Finally, we discuss the...explores the use of supervised machine learning to identify peer - to- peer hosts, without using port numbers or other application-specific information

  11. Laser-induced glass-crystallization phenomena of GeSe2 investigated by light scattering

    NASA Astrophysics Data System (ADS)

    Haro, E.; Xu, Z. S.; Morhange, J.-F.; Balkanski, M.; Espinosa, G. P.; Phillips, J. C.

    1985-07-01

    Recrystallization of glassy GeSe2 under laser irradiation has been studied with use of Raman spectroscopy. A threshold irradiation power level below which no changes in the local molecular structure of the system can be detected has been defined. For an irradiation power above the threshold, three stages of transformation have been identified: The first stage is characterized by the nucleation of clusters or submicrocrystallites which remain embedded in a continuum glass matrix. The second stage is characterized by the coexistence of clusters of various sizes. Up to this stage, the system is fully reversible. The last stage is reached when the crystallites coalesce to form a polycrystalline material.

  12. Prediction of Magnetic and Electronic Phenomena in Molecular-Assembled Crystals

    DTIC Science & Technology

    2008-12-19

    done with standard public-domain message-passing-interface protocols, and the program currently runs on Linux-based beowulf clusters , IBM SP’s and...structure and vibrational spectra of C2B10-based clusters and films," Phys. Rev. B 74, 035109 (2006).

  13. Electromagnetic emission memory phenomena related to LiF ionic crystal deformation

    NASA Astrophysics Data System (ADS)

    Mavromatou, C.; Tombras, G. S.; Ninos, D.; Hadjicontis, V.

    2008-04-01

    During the uniaxial compression of LiF ionic monocrystals, acoustic and electromagnetic emissions (EME) are detected. We observed that when the compression is performed in successive loading, unloading cycles and these emissions are being monitored, no new emissions will occur unless the maximum stress of the previous cycle is exceeded, meaning that the material presents memory characteristics. This is observed not only for the acoustic emission (AE), which is the well known Kaiser effect, but for the EME as well. In other words, the material appears to memorize and reveal the previously maximum stress it suffered while being deformed. The importance of an electromagnetic memory feature of a material can be related to various applications in material science, especially when the detection of AE is not feasible or gives false alert. Such cases may very well be earthquakes' predictive indications, monitoring of mines' stability, imminent landslides, etc.

  14. Phase transitions and reentrant phenomena in liquid crystals having both rigid and flexible intramolecular joints

    NASA Astrophysics Data System (ADS)

    Pyżuk, W.; Górecka, E.; Mieczkowski, J.; Przedmojski, J.

    1992-07-01

    Two series of liquid-crystalline compounds having three phenyl rings separated by flexible spacer —CH(CH{3})CH{2}—COO— and by rigid azo and azoxy group, were studied by DSC, optical and X-ray methods. For esters of dl-3-(4^{prime}-nitro)-phenylbutyric acid with 4^{prime}-alkoxy-phenylazo-phenol-4 having dodecyloxy or longer terminal chains, as well as for related azoxy compounds, a narrow (even below 5 K) reentrant or inverted nematic phase appearing between partly bilayer and monolayer smectics A was observed. For higher homologues of the azoxy series additional smectic phases appear, leading to the occurrence of new multicritical points, e.g. the critical end point Ad Cd N^re. On each of the lines, which separate nematic from smectic A phases, transitions are of weakly first or second-order and more than one tricritical point can occur. On the A{1} N/A{1} N^re line, a simple N A{1} tricritical point is observed at T_NI/T_AN = 0.834. The presence of further critical points depends on the components of the binary system involved. Four of the azoxy compounds studied undergo a second order phase transition between partly bilayer smectics, Ad and Cd. Such a transition is accompanied by a jumb in the specific heat, varying linearly with the length of the molecular tails. Various temperature dependences of the layer spacing in the Ad phase are observed for subsequent homologues from the azoxy series. Plusieurs cristaux liquides composés de trois groupements phényl séparés par un groupement —CH(CH{3})CH{2}—COO—, ainsi que par des groupements azo et azoxy, ont été examinés par AED, méthodes optiques et par rayons X. Pour des esters de l'acide dl-3-(4^{prime}-nitro)phénylbutyrique et de 4^{prime}-alkoxy-phénylazo-phénol-4 ayant comme terminaison une chaîne dodecyloxy ou bien plus longue, ainsi que pour des composés azoxy relatif, on observe (même au-dessous de 5 K) une étroite phase nématique réentrante ou inverse entre les phases smectiques : monocouche et partiellement bicouche. Pour des homologues plus longs dans la série des composés azoxy, on a constaté l'existence d'autres phases smectiques ce qui implique l'apparition, sur les diagrammes des phases, de nouveau points multicritiques, par exemple le point Ad Cd N^re. Sur chaque ligne séparant les phases smectiques A de la phase nématique les transitions sont faiblement du premier ordre ou du deuxième ordre ce qui mène dans certain cas à plus qu'un point tricritique. Sur la ligne A{1} N/A{1} N^re on observe à T_NI/T_AN = 0,834 un simple point tricritique N A{1} — l'apparition des autres dépend du choix des constituants du système binaire. Dans le cas de quatre composés azoxy on a constaté une transition du deuxième ordre entre les phases smectiques partiellement bicouches, Ad et Cd. La transition est accompagnée d'un brusque changement de la chaleur spécifique qui varie linéairement avec la longueur de la queue de la molécule. Pour des homologues suivants de la série des composés azoxy on observe différentes dépendances en température de la distance entre les couches de la phase Ad.

  15. Hallucinations, sleep fragmentation, and altered dream phenomena in Parkinson's disease.

    PubMed

    Pappert, E J; Goetz, C G; Niederman, F G; Raman, R; Leurgans, S

    1999-01-01

    In a series of consecutively randomized outpatients who had Parkinson's disease (PD), we examined the association of three behaviors: sleep fragmentation, altered dream phenomena, and hallucinations/illusions. Using a log-linear model methodology, we tested the independence of each behavior. Sixty-two percent of the subjects had sleep fragmentation, 48% had altered dream phenomena, and 26% had hallucinations/illusions. Eighty-two percent of the patients with hallucinations/illusions experienced some form of sleep disorder. The three phenomena were not independent. The interaction between sleep fragmentation and altered dream phenomena was strongly statistically significant. Likewise, a significant interaction existed between altered dream phenomena and hallucinations/illusions. No interaction occurred between sleep fragmentation and hallucinations/illusions. Sleep fragmentation, altered dream phenomena, and hallucinations/illusions in PD should be considered distinct but often overlapping behaviors. The close association between altered dream phenomena and hallucinations suggests that therapeutic interventions aimed at diminishing dream-related activities may have a specific positive impact on hallucinatory behavior.

  16. Thermal and x-ray analysis on the origin of double melting phenomena of poly(L-lactic acid) films

    NASA Astrophysics Data System (ADS)

    Ling, Xiaoyun

    Thermal analysis is one of the most commonly used techniques to characterize the structure and properties of semicrystalline polymers. However, the complexity involved is often overlooked, leading to erroneous or, at least, questionable results and interpretations. In the present study we carry out an extensive investigation of the complex thermal behavior of poly(L-lactic acid), PLLA, films prepared under a wide range of crystallization conditions, including isothermal and non-isothermal crystallization from both the glassy state and the melt. The primary techniques used were differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC), wide-angle x-ray diffraction (WAXD), and small angle x-ray scattering (SAXS). A major goal of the research was to sort out the various phenomena and to understand the mechanisms that produced them. Depending on the sample preparation conditions up to three crystallization peaks and two melting peaks could be observed during heating in the DSC. The occurrence of double melting is a function of crystallization temperature, crystallization time, heating rate, and molecular weight. It occurs under many experimental conditions, and it depends largely on the size and perfection of initial crystals, not the overall initial crystallinity, nor the completion of crystallization. It was found that the first endotherm was often obscured by the recrystallization exotherm. It was concluded that PLLA double melting originates mainly from the melt-recrystallization of metastable crystals. For samples cold-crystallized above 140°C, it is due to a dual lamellar population present in the samples. For crystallization below 120°C, a proposal in the literature that PLLA double melting is caused by the formation and subsequent transformation of beta-phase could not be ruled out. A unique double "cold-crystallization" peak was observed when amorphous PLLA was heated at 10°C/min. It was concluded to result from the sum of conventional cold-crystallization

  17. Astrophysical phenomena related to supermassive black holes

    NASA Astrophysics Data System (ADS)

    Pott, Jörg-Uwe

    2006-12-01

    The thesis contains the results of my recent projects in astrophysical research. All projects aim at pushing the limits of our knowledge about the interaction between a galaxy, the fundamental building block of today's universe, and a supermassive black hole (SMBH) at its center. Over the past years a lot of observational evidence has been gathered for the current understanding, that at least a major part of the galaxies with a stellar bulge contain central SMBHs. The typical extragalactic approach consists of searching for the spectroscopic pattern of Keplerian rotation, produced by stars and gas, when orbiting a central dark mass (Kormendy & Richstone 1995). It suggests that a significant fraction of large galaxies host in their very nucleus a SMBH of millions to billions of solar masses (Kormendy & Gebhardt 2001). In the closest case, the center of our Milky Way, the most central stars, which can be imaged, were shown to move on orbits with circulation times of a few decades only, evidencing a mass and compactness of the dark counter part of the Keplerian motion, which can only be explained by a SMBH (Eckart & Genzel 1996; Ghez et al. 2000; Schödel et al. 2002). Having acknowledged the widespread existence of SMBHs the obvious next step is investigating the interaction with their environment. Although the basic property of a SMBH, which is concentrating a huge amount of mass in a ludicrously small volume defined by the Schwarzschild radius, only creates a deep gravitational trough, its existence evokes much more phenomena than simply attracting the surrounding matter. It can trigger or exacerbate star formation via tidal forces (Morris 1993). It shapes the distribution of its surrounding matter to accretion discs, which themselves release gravitational potential energy as radiation, possibly due to magnetic friction (Blandford 1995). The radiation efficiency of such active galactic nuclei (AGN) can become roughly 100 times more efficient than atomic nuclear

  18. Time-Variable Phenomena in the Jovian System

    NASA Technical Reports Server (NTRS)

    Belton, Michael J. S. (Editor); West, Robert A. (Editor); Rahe, Jurgen (Editor); Pereyda, Margarita

    1989-01-01

    The current state of knowledge of dynamic processes in the Jovian system is assessed and summaries are provided of both theoretical and observational foundations upon which future research might be based. There are three sections: satellite phenomena and rings; magnetospheric phenomena, Io's torus, and aurorae; and atmospheric phenomena. Each chapter discusses time dependent theoretical framework for understanding and interpreting what is observed; others describe the evidence and nature of observed changes or their absence. A few chapters provide historical perspective and attempt to present a comprehensive synthesis of the current state of knowledge.

  19. Analytical investigation of critical phenomena in MHD power generators

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Critical phenomena in the Arnold Engineering Development Center (AEDC) High Performance Demonstration Experiment (HPDE) and the U.S. U-25 Experiment, are analyzed. The performance of a NASA specified 500 MW(th) flow train is analyzed. Critical phenomena analyzed include: Hall voltage overshoots; optimal load schedules; parametric dependence of the electrode voltage drops; boundary layer behavior; near electrode phenomena with finite electrode segmentation; current distribution in the end regions; scale up rules; optimum Mach number distribution; and the effects of alternative cross sectional shapes.

  20. Nonlinear Effects in Photorefractive Crystals.

    NASA Astrophysics Data System (ADS)

    Erbschloe, Donald Ross

    1988-12-01

    phenomena, and laser beam steering. A new gain mechanism for wave mixing in photorefractive crystals is verified experimentally using the unidirectional ring resonator and the linear resonator. The new mechanism depends on two, frequency detuned pump beams and off-Bragg coupling. A comparison with the traditional gain mechanism for wave amplification, using a single pump beam, reveals that the intensity of the oscillating beam with the new mechanism can be four times larger than with a single pump beam. We provide the first quantitative measurement of oscillation in the linear resonator using Bi_ {12}SiO_{20} .

  1. Crystallization of sodium chloride from a concentrated calcium chloride-potassium chloride-sodium chloride solution in a CMSMPR crystallizer: Observation of crystal size distribution and model validation

    NASA Astrophysics Data System (ADS)

    Choi, Byung Sang

    Compared to overwhelming technical data available in other advanced technologies, knowledge about particle technology, especially in particle synthesis from a solution, is still poor due to the lack of available equipment to study crystallization phenomena in a crystallizer. Recent technical advances in particle size measurement such as Coulter counter and laser light scattering have made in/ex situ study of some of particle synthesis, i.e., growth, attrition, and aggregation, possible with simple systems. Even with these advancements in measurement technology, to grasp fully the crystallization phenomena requires further theoretical and technical advances in understanding such particle synthesis mechanisms. Therefore, it is the motive of this work to establish the general processing parameters and to produce rigorous experimental data with reliable performance and characterization that rigorously account for the crystallization phenomena of nucleation, growth, aggregation, and breakage including their variations with time and space in a controlled continuous mixed-suspension mixed-product removal (CMSMPR) crystallizer. This dissertation reports the results and achievements in the following areas: (1) experimental programs to support the development and validation of the phenomenological models and generation of laboratory data for the purpose of testing, refining, and validating the crystallization process, (2) development of laboratory well-mixed crystallizer system and experimental protocols to generate crystal size distribution (CSD) data, (3) the effects of feed solution concentration, crystallization temperature, feed flow rate, and mixing speed, as well as different types of mixers resulting in the evolution of CSDs with time from a concentrated brine solution, (4) with statistically designed experiments the effects of processing variables on the resultant particle structure and CSD at steady state were quantified and related to each of those operating

  2. INVESTIGATIONS INTO BIOFOULING PHENOMENA IN FINE PORE AERATION DEVICES

    EPA Science Inventory

    Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine pore diffusers were obtained from five municipal wastewa...

  3. Deliquescent phenomena of ambient aerosols on the North China Plain

    NASA Astrophysics Data System (ADS)

    Kuang, Y.; Zhao, C. S.; Ma, N.; Liu, H. J.; Bian, Y. X.; Tao, J. C.; Hu, Min

    2016-08-01

    In this study, we report that the deliquescent phenomena of ambient aerosols on the North China Plain are frequently observed using a humidified nephelometer system. The deliquescence relative humidity (RH) primarily ranges from 73% to 81%, with an average of 76.8%. The observed deliquescent phenomena of ambient aerosols exhibit distinct diurnal patterns and are highly correlated with ammonium sulfate. The diurnal variations of ammonium and nitrate may play significant roles on occurrences of observed deliquescent phenomena. The frequently observed deliquescent phenomena of ambient aerosols in this paper imply that current parameterization schemes that describe the RH dependence of particle light scattering may result in a significant bias when estimating aerosol effects on climate.

  4. Analysis of nuclear reactor instability phenomena. Progress report

    SciTech Connect

    Lahey, R.T. Jr.

    1993-03-01

    The phenomena known as density-wave instability often occurs in phase change systems, such as boiling water nuclear reactors (BWRS). Our current understanding of density-wave oscillations is in fairly good shape for linear phenomena (eg, the onset of instabilities) but is not very advanced for non-linear phenomena [Lahey and Podowski, 1989]. In particular, limit cycle and chaotic instability modes are not well understood in boiling systems such as current and advanced generation BWRs (eg, SBWR). In particular, the SBWR relies on natural circulation and is thus inherently prone to problems with density-wave instabilities. The purpose of this research is to develop a quantitative understanding of nonlinear nuclear-coupled density-wave instability phenomena in BWRS. This research builds on the work of Achard et al [1985] and Clausse et al [1991] who showed, respectively, that Hopf bifurcations and chaotic oscillations may occur in boiling systems.

  5. Probing Cytological and Reproductive Phenomena by Means of Bryophytes.

    ERIC Educational Resources Information Center

    Newton, M. E.

    1985-01-01

    Describes procedures (recommended for both secondary and college levels) to study mitosis, Giemsa C-banding, reproductive phenomena (including alternation of generations), and phototropism in mosses and liverworts. (JN)

  6. Ambroise August Liébeault and psychic phenomena.

    PubMed

    Alvarado, Carlos S

    2009-10-01

    Some nineteenth-century hypnosis researchers did not limit their interest to the study of the conventional psychological and behavioral aspects of hypnosis, but also studied and wrote about psychic phenomena such as mental suggestion and clairvoyance. One example, and the topic of this paper, was French physician Ambroise August Liébeault (1823-1904), who influenced the Nancy school of hypnosis. Liébeault wrote about mental suggestion, clairvoyance, mediumship, and even so-called poltergeists. Some of his writings provide conventional explanations of the phenomena. Still of interest today, Liébeault's writings about psychic phenomena illustrate the overlap that existed during the nineteenth-century between hypnosis and psychic phenomena--an overlap related to the potentials of the mind and its subconscious activity.

  7. Hydrogen gas storage in fluorinated ultramicroporous tunnel crystal.

    PubMed

    Kataoka, Keisuke; Katagiri, Toshimasa

    2012-08-21

    We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder.

  8. Department of Energy Natural Phenomena Hazards Mitigation Program

    SciTech Connect

    Murray, R.C.

    1993-09-01

    This paper will present a summary of past and present accomplishments of the Natural Phenomena Hazards Program that has been ongoing at Lawrence Livermore National Laboratory since 1975. The Natural Phenomena covered includes earthquake; winds, hurricanes, and tornadoes; flooding and precipitation; lightning; and volcanic events. The work is organized into four major areas (1) Policy, requirements, standards, and guidance (2) Technical support, research development, (3) Technology transfer, and (4) Oversight.

  9. Aberration vignetting phenomena and its visualization in wide angular objectives

    NASA Astrophysics Data System (ADS)

    Livshits, Irina; Letunovskaya, Marina; Potemin, Igor; Okishev, Sergey; Zhdanov, Dmitry

    2016-11-01

    Aberration vignetting phenomena changes light distribution in the image plane. A method of physically accurate simulation of this effect in optical devices is presented. We modified a stochastic ray tracing technique to use it for the analysis and visualization of the aberration vignetting. Some useful illustrations with a number of visual examples of these phenomena for different optical systems are given: bi-concentric lens, wide-angle lens, fish-eye lenses, etc.

  10. Satellite SAR Exploitation and Imaging and Measurement of Oceanic Phenomena

    DTIC Science & Technology

    2014-09-30

    of Oceanic Phenomena Hans C. Graber CSTARS - University of Miami 11811 SW 168th Street Miami, FL 33177-, USA phone: (305) 421-4952, fax: (305... Oceanic Phenomena 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT...typhoons, internal waves, ocean surface features, sea state prediction and coastal dynamics. To achieve this, a variety of satellite SAR sensors with

  11. Unusual radio and plasma wave phenomena observed in March 1991

    NASA Technical Reports Server (NTRS)

    Reiner, M. J.; Stone, R. G.; Fainberg, J.

    1992-01-01

    During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Some of these URAP observations cannot be explained by mechanisms usually attributed to interplanetary (IP) radio emissions and Langmuir wave activity and require other interpretations.

  12. Unusual radio and plasma wave phenomena observed in March 1991

    NASA Astrophysics Data System (ADS)

    Reiner, M. J.; Stone, R. G.; Fainberg, J.

    1992-06-01

    During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Some of these URAP observations cannot be explained by mechanisms usually attributed to interplanetary (IP) radio emissions and Langmuir wave activity and require other interpretations.

  13. Classification of Transient Phenomena in Distribution System using wavelet Transform

    NASA Astrophysics Data System (ADS)

    Sedighi, Alireza

    2014-05-01

    An efficient procedure for classification of transient phenomena in distribution systems is proposed in this paper. The proposed method has been applied to classify some transient phenomena such as inrush current, load switching, capacitor switching and single phase to ground fault. The new scheme is based on wavelet transform algorithm. All of the events for feature extraction and test are simulated using Electro Magnetic Transient Program (EMTP). Results show high accuracy of proposed method.

  14. Swimming bacteria in liquid crystal

    NASA Astrophysics Data System (ADS)

    Sokolov, Andrey; Zhou, Shuang; Aranson, Igor; Lavrentovich, Oleg

    2014-03-01

    Dynamics of swimming bacteria can be very complex due to the interaction between the bacteria and the fluid, especially when the suspending fluid is non-Newtonian. Placement of swimming bacteria in lyotropic liquid crystal produces a new class of active materials by combining features of two seemingly incompatible constituents: self-propelled live bacteria and ordered liquid crystals. Here we present fundamentally new phenomena caused by the coupling between direction of bacterial swimming, bacteria-triggered flows and director orientations. Locomotion of bacteria may locally reduce the degree of order in liquid crystal or even trigger nematic-isotropic phase transition. Microscopic flows generated by bacterial flagella disturb director orientation. Emerged birefringence patterns allow direct optical observation and quantitative characterization of flagella dynamics. At high concentration of bacteria we observed the emergence of self-organized periodic texture caused by bacteria swimming. Our work sheds new light on self-organization in hybrid bio-mechanical systems and can lead to valuable biomedical applications. Was supported by the US DOE, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under the Contract No. DE AC02-06CH11357.

  15. Light flash phenomena induced by HzE particles

    NASA Technical Reports Server (NTRS)

    Mcnulty, P. J.; Pease, V. P.

    1980-01-01

    Astronauts and Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes are closed and adapted to darkness. These phenomena have been collectively labelled as light flashes. Visual phenomena which are similar in appearance to those observed in space have been demonstrated at the number of accelerator facilities by expressing the eyes of human subjects to beams of various types of radiation. In some laboratory experiments Cerenkov radiation was found to be the basis for the flashes observed while in other experiments Cerenkov radiation could apparently be ruled out. Experiments that differentiate between Cerenkov radiation and other possible mechanisms for inducing visual phenomena was then compared. The phenomena obtained in the presence and absence of Cerenkov radiation were designed and conducted. A new mechanism proposed to explain the visual phenomena observed by Skylab astronauts as they passed through the South Atlantic Anomaly, namely nuclear interactions in and near the sensitive layer of the retina, is covered. Also some studies to search for similar transient effects of space radiation on sensors and microcomputer memories are described.

  16. Detecting psychological phenomena: taking bottom-up research seriously.

    PubMed

    Haig, Brian D

    2013-01-01

    For more than 50 years, psychology has been dominated by a top-down research strategy in which a simplistic account of the hypothetico-deductive method is paired with null hypothesis testing in order to test hypotheses and theories. As a consequence of this focus on testing, psychologists have failed to pay sufficient attention to a complementary, bottom-up research strategy in which data-to-theory research is properly pursued.This bottom-up strategy has 2 primary aspects: the detection of phenomena, mostly in the form of empirical generalizations, and the subsequent understanding of those phenomena through the abductive generation of explanatory theories. This article provides a methodologically informative account of phenomena detection with reference to psychology. It begins by presenting the important distinctions between data, phenomena, and theory. It then identifies a number of different methodological strategies that are used to identify empirical phenomena. Thereafter, it discusses aspects of the nature of science that are prompted by a consideration of the distinction between data, phenomena, and explanatory theory. Taken together, these considerations press for significant changes in the way we think about and practice psychological research. The adoption of these changes would help psychology correct a number of its major current research deficiencies.

  17. [Non-epileptic motor paroxysmal phenomena in wakefulness in childhood].

    PubMed

    Ruggieri, Víctor L; Arberas, Claudia L

    2013-09-06

    Paroxysmal events in childhood are a challenge for pediatric neurologists, given its highly heterogeneous clinical manifestations, often difficult to distinguish between phenomena of epileptic seizure or not. The non-epileptic paroxysmal episodes are neurological phenomena, with motor, sensory symptoms, and/or sensory impairments, with or without involvement of consciousness, epileptic phenomena unrelated, so no electroencephalographic correlative expression between or during episodes. From the clinical point of view can be classified into four groups: motor phenomena, syncope, migraine (and associated conditions) and acute psychiatric symptoms. In this paper we analyze paroxysmal motor phenomena in awake children, dividing them according to their clinical manifestations: extrapyramidal episodes (paroxysmal kinesiogenic, non kinesiogenic and not related to exercise dyskinesias, Dopa responsive dystonia) and similar symptoms of dystonia (Sandifer syndrome); manifestations of startle (hyperekplexia); episodic eye and head movements (benign paroxysmal tonic upward gaze nistagmus deviation); episodic ataxia (familial episodic ataxias, paroxysmal benign vertigo); stereotyped and phenomena of self-gratification; and myoclonic events (benign myoclonus of early infancy). The detection of these syndromes will, in many cases, allow an adequate genetic counseling, initiate a specific treatment and avoid unnecessary additional studies. Molecular studies have demonstrated a real relationship between epileptic and non-epileptic basis of many of these entities and surely the identification of the molecular basis and understanding of the pathophysiological mechanisms in many of them allow us, in the near future will benefit our patients.

  18. Theoretical model of crystal growth shaping process

    NASA Astrophysics Data System (ADS)

    Tatarchenko, V. A.; Uspenski, V. S.; Tatarchenko, E. V.; Nabot, J. Ph.; Duffar, T.; Roux, B.

    1997-10-01

    A theoretical investigation of the crystal growth shaping process is carried out on the basis of the dynamic stability concept. The capillary dynamic stability of shaped crystal growth processes for various forms of the liquid menisci is analyzed using the mathematical model of the phenomena in the axisymmetric case. The catching boundary condition of the capillary boundary problem is considered and the limits of its application for shaped crystal growth modeling are discussed. The static stability of a liquid free surface is taken into account by means of the Jacobi equation analysis. The result is that a large number of menisci having drop-like shapes are statically unstable. A few new non-traditional liquid meniscus shapes (e.g., bubbles and related shapes) are proposed for the case of a catching boundary condition.

  19. Biological Macromolecule Crystallization Database

    National Institute of Standards and Technology Data Gateway

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  20. Investigaccion-accion en la sala de clases sobre las creencias de la cultura de la ciencia de un grupo de estudiantes universitarios y su relacion reciproca con el aprendizaje de las ciencias biologicas

    NASA Astrophysics Data System (ADS)

    Cordova-Santiago, Lizzette Astrid

    La investigacion---accion que se llevo a cabo en la sala de clases tenia como punto de partida las creencias de la cultura de la ciencia de un grupo de estudiantes universitarios para luego examinar sus implicaciones en el proceso de aprendizaje de las Ciencias Biologicas. ¿Que se supone que hagan las creencias en relacion con el aprendizaje? ¿En que consiste incorporar este aspecto a la practica educativa universitaria? Utilizando el modelo de Kemmis y McTaggart (1987) la investigacion-accion se planteo como un proceso dinamico en cuatro momentos en espiral constituidos por la planificacion, la accion, la observacion y la reflexion. Cada una de las fases tuvo una intencion retrospectiva y prospectiva formando una espiral de autorreflexion del conocimiento y la accion. Se llevaron a cabo audio grabaciones en clases y analisis de documentos. Ademas, la profesora-investigadora hizo un portafolio para reflexionar sobre las creencias de la cultura de la ciencia que tienen los estudiantes y las creencias del aprendizaje que tiene la profesora y sobre como la comprension de estos elementos ayudo a mejorar su practica educativa a traves del tiempo. Los resultados obtenidos apuntan a que las creencias de la cultura de la ciencia que tiene el grupo de estudiantes son diversas. Ellos si creen que la ciencia tiene una cultura la cual describieron como: complicada y desconocida que evoluciona constantemente, que es un conjunto de metodos, que es altamente tecnologica, que resuelve problemas de salud, ayuda a interpretar la realidad del mundo que los rodea y su origen y que existen unas intersecciones entre la ciencia y el poder. Sobre las creencias del proceso de aprendizaje de la profesora-investigadora, estas senalan que el modelaje de actores, la vision de la academia que tiene ella asi como la participacion y negociacion entre todos los involucrados en el proceso educativo, son factores que inciden en el proceso de aprendizaje.

  1. Crystallization process

    DOEpatents

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  2. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  3. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  4. Visualization of atomic-scale phenomena in superconductors: application to FeSe

    DOE PAGES

    Choubey, Peayush; Berlijn, Tom; Kreisel, Andreas; ...

    2014-10-31

    Here we propose a simple method of calculating inhomogeneous, atomic-scale phenomena in superconductors which makes use of the wave function information traditionally discarded in the construction of tight-binding models used in the Bogoliubov-de Gennes equations. The method uses symmetry- based first principles Wannier functions to visualize the effects of superconducting pairing on the distribution of electronic states over atoms within a crystal unit cell. Local symmetries lower than the global lattice symmetry can thus be exhibited as well, rendering theoretical comparisons with scanning tunneling spectroscopy data much more useful. As a simple example, we discuss the geometric dimer states observedmore » near defects in superconducting FeSe.« less

  5. Mesoscopic description of hot spot phenomena: a route for hybrid multiscale simulations

    NASA Astrophysics Data System (ADS)

    Maillet, Jean-Bernard

    2015-06-01

    We describe large scale simulations of hot spot phenomena in single TATB crystals within the DPDE framework. The mesoscopic DPDE model is calibrated on all atom simulations, and particular attention is given to the rate of heat exchange between intramolecular and intermolecular degrees of freedom, which control the non-equilibrium behaviour of the system. Simulations of pore collapse at different shock speeds and for different pore sizes are performed, and a criterium for the quantification of the hot spot energy is proposed. These results are considered as reference data for subsequent comparison with top down simulations of similar processes. We present a reformulation of the (hydrodynamic) SDPD method allowing a direct coupling with the DPDE model, then opening the route for hybrid multiscale simulations.

  6. Inception of ice accretion by ice crystal impact

    NASA Astrophysics Data System (ADS)

    Löwe, Jens; Kintea, Daniel; Baumert, Arne; Bansmer, Stephan; Roisman, Ilia V.; Tropea, Cameron

    2016-09-01

    In this experimental and theoretical study the ice accretion phenomena on a heated cylinder in Braunschweig Icing Wind Tunnel are investigated. The ice crystal size, velocity, the liquid-to-total mass ratio are accurately controlled. The evolution of the cylinder temperature, the time required for the inception of the ice accretion, and the ice accretion rate are measured for various operating conditions. The surface temperature of the solid target is determined by balancing the heating power in the wall and the cooling effect of the stream of ice particles. We have discovered that the inception of the ice crystal accretion is determined by the instant when the surface temperature of the heated target reduces to the freezing temperature. This result will help to model the phenomena of ice crystal accretion.

  7. PARAMAGNETIC RELAXATION IN CRYSTALS.

    DTIC Science & Technology

    CRYSTALS, PARAMAGNETIC RESONANCE, RELAXATION TIME , CRYSTAL DEFECTS, QUARTZ, GLASS, STRAIN(MECHANICS), TEMPERATURE, NUCLEAR SPINS, HYDROGEN, CALCIUM COMPOUNDS, FLUORIDES, COLOR CENTERS, PHONONS, OXYGEN.

  8. Grain Boundary and Interface Phenomena in Deformed Rocks - Implications for Creep Processes

    NASA Astrophysics Data System (ADS)

    White, J. C.

    2015-12-01

    The scaling of ductile rheology within the lithospheric crust can be examined as the progressive aggregation of point and line defect motion and interaction that culminates in the cooperative behavior of grain boundaries and like interfaces. Even though the role of interfaces in mediating defect motion, and in turn macroscopic ductility, is well recognized, many details of interface structure and function remain unresolved. As a contribution to the latter, grain boundary phenomena studied by transmission electron microscopy are described from different pressure-temperature conditions (greenschist to granulite grade) in concert with the macroscopic deformation response. In generally, the interfaces have important differences from classic models based on metals and simple non-metals. The combination of crystal-chemical complexity and compositional heterogeneity of crustal materials is reflected in grain boundary features that include classic coincident-boundary types, grain boundary ledges, finite width interfaces, grain boundary cavitation, dislocation-diffusion metamorphic effects and intra-/ intercrystalline defect interactions. The need to establish the range of interface phenomena is seen in the fact that grain boundary activity is the primary factor in grain-size sensitive (GSS) flow where grain size is in effect an easily observable proxy for the fractional grain boundary area (volume) of the material.

  9. Comprehending emergent systems phenomena through direct-manipulation animation

    NASA Astrophysics Data System (ADS)

    Aguirre, Priscilla Abel

    This study seeks to understand the type of interaction mode that best supports learning and comprehension of emergent systems phenomena. Given that the literature has established that students hold robust misconceptions of such phenomena, this study investigates the influence of using three types of interaction; speed-manipulation animation (SMN), post-manipulation animation (PMA) and direct-manipulation animation (DMA) for increasing comprehension and testing transfer of the phenomena, by looking at the effect of simultaneous interaction of haptic and visual channels on long term and working memories when seeking to comprehend emergent phenomena. The questions asked were: (1) Does the teaching of emergent phenomena, with the aid of a dynamic interactive modeling tool (i.e., SMA, PMA or DMA), improve students' mental model construction of systems, thus increasing comprehension of this scientific concept? And (2) does the teaching of emergent phenomena, with the aid of a dynamic interactive modeling tool, give the students the necessary complex cognitive skill which can then be applied to similar (near transfer) and/or novel, but different, (far transfer) scenarios? In an empirical study undergraduate and graduate students were asked to participate in one of three experimental conditions: SMA, PMA, or DMA. The results of the study found that it was the participants of the SMA treatment condition that had the most improvement in post-test scores. Students' understanding of the phenomena increased most when they used a dynamic model with few interactive elements (i.e., start, stop, and speed) that allowed for real time visualization of one's interaction on the phenomena. Furthermore, no indication was found that the learning of emergent phenomena, with the aid of a dynamic interactive modeling tool, gave the students the necessary complex cognitive skill which could then be applied to similar (near transfer) and/or novel, but different, (far transfer) scenarios

  10. PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media

    NASA Astrophysics Data System (ADS)

    Eikerling, Michael

    2011-06-01

    Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent

  11. Using Inorganic Crystals To Grow Protein Crystals

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.; Mcpherson, Alexander A.

    1989-01-01

    Solid materials serve as nucleating agents. Protein crystals induced by heterogeneous nucleation and in some cases by epitaxy to grow at lower supersaturations than needed for spontaneous nucleation. Heterogeneous nucleation makes possible to grow large, defect-free single crystals of protein more readily. Such protein crystals benefits research in biochemistry and pharmacology.

  12. Laser-induced crystallization and crystal growth.

    PubMed

    Sugiyama, Teruki; Masuhara, Hiroshi

    2011-11-04

    Recent streams of laser studies on crystallization and crystal growth are summarized and reviewed. Femtosecond multiphoton excitation of solutions leads to their ablation at the focal point, inducing local bubble formation, shockwave propagation, and convection flow. This phenomenon, called "laser micro tsunami" makes it possible to trigger crystallization of molecules and proteins from their supersaturated solutions. Femtosecond laser ablation of a urea crystal in solution triggers the additional growth of a single daughter crystal. Intense continuous wave (CW) near infrared laser irradiation at the air/solution interface of heavy-water amino acid solutions results in trapping of the clusters and evolves to crystallization. A single crystal is always prepared in a spatially and temporally controlled manner, and the crystal polymorph of glycine depends on laser power, polarization, and solution concentration. Upon irradiation at the glass/solution interface, a millimeter-sized droplet is formed, and a single crystal is formed by shifting the irradiation position to the surface. Directional and selective crystal growth is also possible with laser trapping. Finally, characteristics of laser-induced crystallization and crystal growth are summarized.

  13. In situ fast ellipsometric analysis of repetitive surface phenomena

    NASA Astrophysics Data System (ADS)

    Costa, J.; Campmany, J.; Canillas, A.; Andújar, J. L.; Bertran, E.

    1997-08-01

    We present an ellipsometric technique and ellipsometric analysis of repetitive phenomena, based on the experimental arrangement of conventional phase modulated ellipsometers (PME) conceived to study fast surface phenomena in repetitive processes such as periodic and triggered experiments. Phase modulated ellipsometry is a highly sensitive surface characterization technique that is widely used in the real-time study of several processes such as thin film deposition and etching. However, fast transient phenomena cannot be analyzed with this technique because precision requirements limit the data acquisition rate to about 25 Hz. The presented new ellipsometric method allows the study of fast transient phenomena in repetitive processes with a time resolution that is mainly limited by the data acquisition system. As an example, we apply this new method to the study of surface changes during plasma enhanced chemical vapor deposition of amorphous silicon in a modulated radio frequency discharge of SiH4. This study has revealed the evolution of the optical parameters of the film on the millisecond scale during the plasma on and off periods. The presented ellipsometric method extends the capabilities of PME arrangements and permits the analysis of fast surface phenomena that conventional PME cannot achieve.

  14. Fracture Phenomena in Foams: From Film Instability to Wave Propagation

    NASA Astrophysics Data System (ADS)

    Hilgenfeldt, Sascha; Stewart, Peter

    2016-11-01

    Injection of a gas into a gas/liquid foam is known to give rise to instability phenomena on a variety of time and length scales. Macroscopically, one observes a propagating gas-filled structure that can display properties of liquid finger propagation as well as of fracture in solids. The observation of both large-scale, finger-like cracks (without film breakage) and brittle cleavage phenomena (consisting of successive film ruptures) is explained through careful modeling of phenomena ranging from thin-film instabilities to friction between bubbles and confining plates. Whereas we use a network approach with full representation of the foam microstructure to model the cracks, we also derive a continuum limit description in order to investigate possible modes of wave propagation and their feedback on the fracture process.

  15. Diffusion phenomena of cells and biomolecules in microfluidic devices

    PubMed Central

    Yildiz-Ozturk, Ece; Yesil-Celiktas, Ozlem

    2015-01-01

    Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules. PMID:26180576

  16. Phenomena Identification and Ranking Technique (PIRT) Panel Meeting Summary Report

    SciTech Connect

    Mark Holbrook

    2007-07-01

    Phenomena Identification and Ranking Technique (PIRT) is a systematic way of gathering information from experts on a specific subject and ranking the importance of the information. NRC, in collaboration with DOE and the working group, conducted the PIRT exercises to identify safety-relevant phenomena for NGNP, and to assess and rank the importance and knowledge base for each phenomenon. The overall objective was to provide NRC with an expert assessment of the safety-relevant NGNP phenomena, and an overall assessment of R and D needs for NGNP licensing. The PIRT process was applied to five major topical areas relevant to NGNP safety and licensing: (1) thermofluids and accident analysis (including neutronics), (2) fission product transport, (3) high temperature materials, (4) graphite, and (5) process heat for hydrogen cogeneration.

  17. Diffusion phenomena of cells and biomolecules in microfluidic devices.

    PubMed

    Yildiz-Ozturk, Ece; Yesil-Celiktas, Ozlem

    2015-09-01

    Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules.

  18. Crisis phenomena after stroke reflected in an existential perspective.

    PubMed

    Nilsson, I; Jansson, L; Norberg, A

    1999-01-01

    The study gains a deeper understanding of crisis phenomena emerging after stroke and focuses on these phenomena viewed in an existential perspective. Ten stroke victims narrated their experiences of their new life situation in open-ended interviews, conducted during the first few months after discharge. The participants were analyzed using a phenomenological-hermeneutic approach. This analysis disclosed an extremely distressing situation related to the individuals' struggle to manage in various dimensions of life. The phenomena were intertwined in a complex way and the critical interpretation involved a transcendence to the existential dimension of life. The situation was metaphorically depicted as "a struggle in the darkness" in a "boundary situation," where the issues ultimately touched on life and death, fate and future, meaning and meaninglessness. The study indicates the significance of existential issues pervading the seemingly concrete struggle to manage life after stroke.

  19. Direct observation of thitherto unobservable quantum phenomena by using electrons.

    PubMed

    Tonomura, Akira

    2005-10-18

    Fundamental aspects of quantum mechanics, which were discussed only theoretically as "thought experiments" in the 1920s and 1930s, have begun to frequently show up in nanoscopic regions owing to recent rapid progress in advanced technologies. Quantum phenomena were once regarded as the ultimate factors limiting further miniaturization trends of microstructured electronic devices, but now they have begun to be actively used as the principles for new devices such as quantum computers. To directly observe what had been unobservable quantum phenomena, we have tried to develop bright and monochromatic electron beams for the last 35 years. Every time the brightness of an electron beam improved, fundamental experiments in quantum mechanics became possible, and quantum phenomena became observable by using the wave nature of electrons.

  20. Multicluster solutions to a multinucleon problem and clustering phenomena

    SciTech Connect

    Gnilozub, I. A.; Kurgalin, S. D.; Tchuvil'sky, Yu. M.

    2008-07-15

    Various concepts of clustering phenomena are discussed. Precise multicluster solutions constructed by the present authors for an A-nucleon problem whose dynamical properties are described by a generalized Elliott Hamiltonian are used as a mathematical formalism of the theory of clustering phenomena in nuclei. It is shown that qualitative features of various clustering phenomena, such as the very fact of the existence of cluster states, their classification, and selectivity of reactions that populate them, are explained within the concept being discussed. The 2{alpha} + bineutron three-cluster states of the {sup 10}Be nucleus are classified, and their spectrum is calculated. It is demonstrated that the results of these calculations are in good agreement with experimental data.

  1. Quantum Simulator for Transport Phenomena in Fluid Flows.

    PubMed

    Mezzacapo, A; Sanz, M; Lamata, L; Egusquiza, I L; Succi, S; Solano, E

    2015-08-17

    Transport phenomena still stand as one of the most challenging problems in computational physics. By exploiting the analogies between Dirac and lattice Boltzmann equations, we develop a quantum simulator based on pseudospin-boson quantum systems, which is suitable for encoding fluid dynamics transport phenomena within a lattice kinetic formalism. It is shown that both the streaming and collision processes of lattice Boltzmann dynamics can be implemented with controlled quantum operations, using a heralded quantum protocol to encode non-unitary scattering processes. The proposed simulator is amenable to realization in controlled quantum platforms, such as ion-trap quantum computers or circuit quantum electrodynamics processors.

  2. Pseudospin-mediated phenomena in photonic graphene (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Song, Daohong; Efremedis, Nikos; Chen, Zhigang

    2016-09-01

    "Photonic graphene" has been demonstrated as a useful platform to study fundamental physics such as edge states and topological insulators. Recently, we have demonstrated pseudospin-mediated generation of topological charges in photonic graphene. Due to sublattice degree of freedom, charge flipping is observed as the sublattices are selectively excited. Our experimental results are confirmed by numerical simulation as well as by theoretical analysis of the 2D Dirac-Weyl equations. In this talk, we will discuss such pseudospin-related phenomena due to the sublattice degree of freedom, along with our recent work on related phenomena due to the graphene valley degree of freedom.

  3. An assessment of Gallistel's (2012) rationalistic account of extinction phenomena.

    PubMed

    Miller, Ralph R

    2012-05-01

    Gallistel (2012) asserts that animals use rationalistic reasoning (i.e., information theory and Bayesian inference) to make decisions that underlie select extinction phenomena. Rational processes are presumed to lead to evolutionarily optimal behavior. Thus, Gallistel's model is a type of optimality theory. But optimality theory is only a theory, a theory about an ideal organism, and its predictions frequently deviate appreciably from observed behavior of animals in the laboratory and the real world. That is, behavior of animals is often far from optimal, as is evident in many behavioral phenomena. Hence, appeals to optimality theory to explain, rather than illuminate, actual behavior are misguided.

  4. Quantum Simulator for Transport Phenomena in Fluid Flows

    PubMed Central

    Mezzacapo, A.; Sanz, M.; Lamata, L.; Egusquiza, I. L.; Succi, S.; Solano, E.

    2015-01-01

    Transport phenomena still stand as one of the most challenging problems in computational physics. By exploiting the analogies between Dirac and lattice Boltzmann equations, we develop a quantum simulator based on pseudospin-boson quantum systems, which is suitable for encoding fluid dynamics transport phenomena within a lattice kinetic formalism. It is shown that both the streaming and collision processes of lattice Boltzmann dynamics can be implemented with controlled quantum operations, using a heralded quantum protocol to encode non-unitary scattering processes. The proposed simulator is amenable to realization in controlled quantum platforms, such as ion-trap quantum computers or circuit quantum electrodynamics processors. PMID:26278968

  5. Critical phenomena experiments in space. [for fluid phase-equilibrium

    NASA Technical Reports Server (NTRS)

    Sengers, J. V.; Moldover, M. R.

    1978-01-01

    The paper analyzes several types of critical phenomena in fluids, shows how they are affected by the presence of gravity, and describes how experiments conducted in an orbiting laboratory under low gravity conditions could extend the range of measurements needed to study critical phenomena. Future experiments are proposed. One would be a careful measurement of the dielectric constant in a low gravity environment. Two basic problems that can benefit especially from space experiments are the specific heat near the critical point and the shear viscosity at the gas-liquid critical point.

  6. Radioactive γ/β tracer to explore dangerous technogenic phenomena

    NASA Astrophysics Data System (ADS)

    Nagorsky, P. M.; Yakovleva, V. S.; Makarov, E. O.; Firstov, P. P.; Kondratyeva, A. G.; Stepanenko, A. A.

    2016-06-01

    A radioactive γ/β tracer to explore dangerous technogenic phenomena has been proposed: the ratio of the measured flux density of β- and γ-radiations in the surface layer of the atmosphere. The time dependence analysis of the ratio of β- and γ-pulse count rate has been carried out. A significant increase of the γ/β ratio was recorded under the cyclone passing through Japan (Fukushima) to Kamchatka. The proposed γ/β tracer can be a very sensitive indicator of nonstationary processes related to hazardous natural and technogenic phenomena.

  7. Fundamental investigation of duct/ESP phenomena. Final report

    SciTech Connect

    Brown, C.A.; Durham, M.D.; Sowa, W.A.; Himes, R.M.; Mahaffey, W.A.

    1991-10-21

    Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

  8. Magnetohydrodynamic (MHD) modelling of solar active phenomena via numerical methods

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1988-01-01

    Numerical ideal MHD models for the study of solar active phenomena are summarized. Particular attention is given to the following physical phenomena: (1) local heating of a coronal loop in an isothermal and stratified atmosphere, and (2) the coronal dynamic responses due to magnetic field movement. The results suggest that local heating of a magnetic loop will lead to the enhancement of the density of the neighboring loops through MHD wave compression. It is noted that field lines can be pinched off and may form a self-contained magnetized plasma blob that may move outward into interplanetary space.

  9. RELAP5-3D code validation for RBMK phenomena

    SciTech Connect

    Fisher, J.E.

    1999-09-01

    The RELAP5-3D thermal-hydraulic code was assessed against Japanese Safety Experiment Loop (SEL) and Heat Transfer Loop (HTL) tests. These tests were chosen because the phenomena present are applicable to analyses of Russian RBMK reactor designs. The assessment cases included parallel channel flow fluctuation tests at reduced and normal water levels, a channel inlet pipe rupture test, and a high power, density wave oscillation test. The results showed that RELAP5-3D has the capability to adequately represent these RBMK-related phenomena.

  10. RELAP5-3D Code Validation for RBMK Phenomena

    SciTech Connect

    Fisher, James Ebberly

    1999-09-01

    The RELAP5-3D thermal-hydraulic code was assessed against Japanese Safety Experiment Loop (SEL) and Heat Transfer Loop (HTL) tests. These tests were chosen because the phenomena present are applicable to analyses of Russian RBMK reactor designs. The assessment cases included parallel channel flow fluctuation tests at reduced and normal water levels, a channel inlet pipe rupture test, and a high power, density wave oscillation test. The results showed that RELAP5-3D has the capability to adequately represent these RBMK-related phenomena.

  11. Molecular tectonics: from crystals to crystals of crystals.

    PubMed

    Marinescu, Gabriela; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2013-12-11

    The in situ combination of M(II) cations (Co, Ni, Cu or Zn) with 2,4,6-pyridinetricarboxylic acid as a ligand, a bisamidinium dication as a H-bond donor tecton and NaOH leads to the formation of anionic metal complexes ML2(2-) and their interconnection into isomorphous 3D H-bonded networks displaying different colours which were used as preformed seed crystals for the formation of crystals of crystals by 3D epitaxial growth.

  12. Liquid crystal interfaces: Experiments, simulations and biosensors

    NASA Astrophysics Data System (ADS)

    Popov, Piotr

    Interfacial phenomena are ubiquitous and extremely important in various aspects of biological and industrial processes. For example, many liquid crystal applications start by alignment with a surface. The underlying mechanisms of the molecular organization of liquid crystals at an interface are still under intensive study and continue to be important to the display industry in order to develop better and/or new display technology. My dissertation research has been devoted to studying how complex liquid crystals can be guided to organize at an interface, and to using my findings to develop practical applications. Specifically, I have been working on developing biosensors using liquid-crystal/surfactant/lipid/protein interactions as well as the alignment of low-symmetry liquid crystals for potential new display and optomechanical applications. The biotechnology industry needs better ways of sensing biomaterials and identifying various nanoscale events at biological interfaces and in aqueous solutions. Sensors in which the recognition material is a liquid crystal naturally connects the existing knowledge and experience of the display and biotechnology industries together with surface and soft matter sciences. This dissertation thus mainly focuses on the delicate phenomena that happen at liquid interfaces. In the introduction, I start by defining the interface and discuss its structure and the relevant interfacial forces. I then introduce the general characteristics of biosensors and, in particular, describe the design of biosensors that employ liquid crystal/aqueous solution interfaces. I further describe the basic properties of liquid crystal materials that are relevant for liquid crystal-based biosensing applications. In CHAPTER 2, I describe the simulation methods and experimental techniques used in this dissertation. In CHAPTER 3 and CHAPTER 4, I present my computer simulation work. CHAPTER 3 presents insight of how liquid crystal molecules are aligned by

  13. Drilling technique for crystals

    NASA Technical Reports Server (NTRS)

    Hunter, T.; Miyagawa, I.

    1977-01-01

    Hole-drilling technique uses special crystal driller in which drill bit rotates at fixed position at speed of 30 rpm while crystal slowly advances toward drill. Technique has been successfully applied to crystal of Rochell salt, Triglycine sulfate, and N-acetyglycine. Technique limits heat buildup and reduces strain on crystal.

  14. Binary liquid phase separation and critical phenomena in a protein/water solution.

    PubMed Central

    Thomson, J A; Schurtenberger, P; Thurston, G M; Benedek, G B

    1987-01-01

    We have investigated the phase diagram of aqueous solutions of the bovine lens protein gamma II-crystallin. For temperatures T less than Tc = 278.5 K, we find that these solutions exhibit a reversible coexistence between two isotropic liquid phases differing in protein concentration. The dilute and concentrated branches of the coexistence curve were characterized, consistently, both by measurements of the two coexisting concentrations, c(T), and by measuring the cloud temperatures for various initial concentrations. We estimate that the critical concentration, cc, is 244 mg of protein per ml solution. The coexistence curve is well represented by the absolute value of (c - cc)/cc = 5.2 square root (Tc - T)/Tc. Using the temperature dependence of the scattered light intensity along isochores parallel to the critical isochore, we estimated the location of the spinodal line and found it to have the form (c - cc)/cc = 3.0 square root (Tc - T)/Tc. The ratio of the widths of the coexistence curve and the spinodal line, (5.2/3.0), is close to the mean-field value square root 3. We have also observed the growth of large crystals of gamma II-crystallin in some of these aqueous solutions and have made preliminary observations as to the factors that promote or delay the onset of crystallization. These findings suggest that selected protein/water systems can serve as excellent model systems for the study of phase transitions and critical phenomena. PMID:3478681

  15. Neutralization of Hydroxide Ion in Melt-Grown NaCl Crystals

    NASA Technical Reports Server (NTRS)

    Otterson, Dumas A.

    1961-01-01

    Many recent studies of solid-state phenomena, particularly in the area of crystal imperfections, have involved the use of melt-grown NaCl single crystals. Quite often trace impurities in these materials have had a prominent effect on these phenomena. Trace amounts of hydroxide ion have been found in melt-grown NaCl crystals. This paper describes a nondestructive method of neutralizing the hydroxide ion in such crystals. Crystals of similar hydroxide content are maintained at an elevated temperature below the melting point of NaCl in a flowing atmosphere containing. dry hydrogen chloride. Heat treatment is continued until an analysis of the test specimens shows no excess hydroxide ion. A colorimetric method previously described4 is used for this analysis.

  16. Mixed crystal organic scintillators

    DOEpatents

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  17. EDITORIAL: Spin-transfer-torque-induced phenomena Spin-transfer-torque-induced phenomena

    NASA Astrophysics Data System (ADS)

    Hirohata, Atsufumi

    2011-09-01

    This cluster, consisting of five invited articles on spin-transfer torque, offers the very first review covering both magnetization reversal and domain-wall displacement induced by a spin-polarized current. Since the first theoretical proposal on spin-transfer torque—reported by Berger and Slonczewski independently—spin-transfer torque has been experimentally demonstrated in both vertical magnetoresistive nano-pillars and lateral ferromagnetic nano-wires. In the former structures, an electrical current flowing vertically in the nano-pillar exerts spin torque onto the thinner ferromagnetic layer and reverses its magnetization, i.e., current-induced magnetization switching. In the latter structures, an electrical current flowing laterally in the nano-wire exerts torque onto a domain wall and moves its position by rotating local magnetic moments within the wall, i.e., domain wall displacement. Even though both phenomena are induced by spin-transfer torque, each phenomenon has been investigated separately. In order to understand the physical meaning of spin torque in a broader context, this cluster overviews both cases from theoretical modellings to experimental demonstrations. The earlier articles in this cluster focus on current-induced magnetization switching. The magnetization dynamics during the reversal has been calculated by Kim et al using the conventional Landau--Lifshitz-Gilbert (LLG) equation, adding a spin-torque term. This model can explain the dynamics in both spin-valves and magnetic tunnel junctions in a nano-pillar form. This phenomenon has been experimentally measured in these junctions consisting of conventional ferromagnets. In the following experimental part, the nano-pillar junctions with perpendicularly magnetized FePt and half-metallic Heusler alloys are discussed from the viewpoint of efficient magnetization reversal due to a high degree of spin polarization of the current induced by the intrinsic nature of these alloys. Such switching can

  18. Pressure cryocooling protein crystals

    DOEpatents

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  19. Large-scale phenomena, chapter 3, part D

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Oceanic phenomena with horizontal scales from approximately 100 km up to the widths of the oceans themselves are examined. Data include: shape of geoid, quasi-stationary anomalies due to spatial variations in sea density and steady current systems, and the time dependent variations due to tidal and meteorological forces and to varying currents.

  20. Nuclear phenomena in low-energy nuclear reaction research.

    PubMed

    Krivit, Steven B

    2013-09-01

    This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat.

  1. Developing Critical Thinking through the Study of Paranormal Phenomena.

    ERIC Educational Resources Information Center

    Wesp, Richard; Montgomery, Kathleen

    1998-01-01

    Argues that accounts of paranormal phenomena can serve as an ideal medium in which to encourage students to develop critical-thinking skills. Describes a cooperative-learning approach used to teach critical thinking in a course on paranormal events. Reports that critical-thinking skills increased and that the course received favorable student…

  2. A Curriculum Framework Based on Archetypal Phenomena and Technologies.

    ERIC Educational Resources Information Center

    Zubrowski, Bernie

    2002-01-01

    Presents an alternative paradigm of curriculum development based on the theory of situated cognition. This approach starts with context rather than concept, gives greater weight to students' interpretative frameworks, and provides for a more holistic development. Presents a grade 1-8 framework that uses archetypal phenomena and technologies as the…

  3. Development of Understanding of Selected Science Phenomena in Young Children.

    ERIC Educational Resources Information Center

    Donaldson, Marcia Jackson

    The major purpose of this study was to investigate developmental patterns of understandings of four types of selected phenomena possessed by economically and racially different boys and girls. A total of 64 boys and girls, 32 blacks and 32 whites, were selected from Head Start, kindergarten, nursery, and primary schooling environments and then…

  4. The Effects of Globalization Phenomena on Educational Concepts

    ERIC Educational Resources Information Center

    Schrottner, Barbara Theresia

    2010-01-01

    It is becoming more and more apparent that globalization processes represent, theoretically as well as practically, a challenge for educational sciences and therefore, it must be addressed within the sphere of education. Accordingly, educational conceptions have to adapt to globalization phenomena and focus more on alternative and innovative…

  5. Binding Phenomena within a Reductionist Theory of Grammatical Dependencies

    ERIC Educational Resources Information Center

    Drummond, Alex

    2011-01-01

    This thesis investigates the implications of binding phenomena for the development of a reductionist theory of grammatical dependencies. The starting point is the analysis of binding and control in Hornstein (2001, 2009). A number of revisions are made to this framework in order to develop a simpler and empirically more successful account of…

  6. Linguistic Studies on English Pronominalization: Syntactic, Discourse and Pragmatic Phenomena.

    ERIC Educational Resources Information Center

    Barnitz, John G.

    To integrate many of the theoretical linguistic studies examining pronoun reference, this paper focuses on tracing the shift from purely transformational syntactic studies of intrasentential phenomena to the wider orientations of discourse and pragmatic studies. The first section describes the classic studies of pronominalization within the…

  7. An Initial Investigation of the Psychedelic Drug Flashback Phenomena

    ERIC Educational Resources Information Center

    Matefy, Robert E.; Krall, Roger G.

    1974-01-01

    This study investigated some characteristics of persons experiencing "flashbacks," and provides systematic descriptions of the flashback phenomena. The drug user showed no significant differences in psychopathological characteristics as measured by the MMPI, nor significant differences in attentional processes as measured by the Embedded Figures…

  8. Coastal Sand Dune Plant Ecology: Field Phenomena and Interpretation

    ERIC Educational Resources Information Center

    McDonald, K.

    1973-01-01

    Discusses the advantages and disadvantages of selecting coastal sand dunes as the location for field ecology studies. Presents a descriptive zonal model for seaboard sand dune plant communities, suggestions concerning possible observations and activities relevant to interpreting phenomena associated with these forms of vegetation, and additional…

  9. Electrostatic phenomena in organic semiconductors: fundamentals and implications for photovoltaics

    NASA Astrophysics Data System (ADS)

    D'Avino, Gabriele; Muccioli, Luca; Castet, Frédéric; Poelking, Carl; Andrienko, Denis; Soos, Zoltán G.; Cornil, Jérôme; Beljonne, David

    2016-11-01

    This review summarizes the current understanding of electrostatic phenomena in ordered and disordered organic semiconductors, outlines numerical schemes developed for quantitative evaluation of electrostatic and induction contributions to ionization potentials and electron affinities of organic molecules in a solid state, and illustrates two applications of these techniques: interpretation of photoelectron spectroscopy of thin films and energetics of heterointerfaces in organic solar cells.

  10. Eighty phenomena about the self: representation, evaluation, regulation, and change

    PubMed Central

    Thagard, Paul; Wood, Joanne V.

    2015-01-01

    We propose a new approach for examining self-related aspects and phenomena. The approach includes (1) a taxonomy and (2) an emphasis on multiple levels of mechanisms. The taxonomy categorizes approximately eighty self-related phenomena according to three primary functions involving the self: representing, effecting, and changing. The representing self encompasses the ways in which people depict themselves, either to themselves or to others (e.g., self-concepts, self-presentation). The effecting self concerns ways in which people facilitate or limit their own traits and behaviors (e.g., self-enhancement, self-regulation). The changing self is less time-limited than the effecting self; it concerns phenomena that involve lasting alterations in how people represent and control themselves (e.g., self-expansion, self-development). Each self-related phenomenon within these three categories may be examined at four levels of interacting mechanisms (social, individual, neural, and molecular). We illustrate our approach by focusing on seven self-related phenomena. PMID:25870574

  11. Undergraduate Laboratory Experiment Modules for Probing Gold Nanoparticle Interfacial Phenomena

    ERIC Educational Resources Information Center

    Karunanayake, Akila G.; Gunatilake, Sameera R.; Ameer, Fathima S.; Gadogbe, Manuel; Smith, Laura; Mlsna, Deb; Zhang, Dongmao

    2015-01-01

    Three gold-nanoparticle (AuNP) undergraduate experiment modules that are focused on nanoparticles interfacial phenomena have been developed. Modules 1 and 2 explore the synthesis and characterization of AuNPs of different sizes but with the same total gold mass. These experiments enable students to determine how particle size affects the AuNP…

  12. Beyond a Dichotomic Approach, the Case of Colour Phenomena

    ERIC Educational Resources Information Center

    Viennot, L.; de Hosson, C.

    2012-01-01

    This research documents the aims and the impact of a teaching experiment concerning colour phenomena. This teaching experiment is designed in order to make students consider not only the spectral composition of light but also its intensity, and to consider the absorption of light by a pigment as relative, instead of as total or zero. Eight…

  13. Many-body phenomena in QED-cavity arrays [Invited

    SciTech Connect

    Tomadin, A.; Fazio, Rosario

    2010-06-15

    Coupled quantum electrodynamics (QED) cavities have been recently proposed as new systems to simulate a variety of equilibrium and nonequilibrium many-body phenomena. We present a brief review of their main properties together with a survey of the latest developments of the field and some perspectives concerning their experimental realizations and possible new theoretical directions.

  14. Plasma crystals: experiments and simulation

    NASA Astrophysics Data System (ADS)

    Piel, A.

    2017-01-01

    Dusty plasmas are a well accessible system to study crystallization of charged-particle systems at room temperature. The large mass compared to atomic particles dramatically slows down the particle velocities. The high transparency of the system allows to trace simultaneously the motion of all particles with quasi-atomic resolution. After a brief overview, the progress in this field is exemplified by studies of spherical three-dimensional plasma crystals, the so-called Yukawa balls. The static structure and eigenmodes are explained in simple terms. It is shown that shielding modifies the expansion of a Yukawa ball from a self-similar explosion to a continuous ablation process that starts at the surface. The experimental progress with three-dimensional diagnostics and laser heating and sophisticated methods for visualising the order inside the shell structure are described. Together with quantifying the diffusion coefficient these investigations reveal the details of the solid-liquid phase transition. Besides thermodynamic aspects, the liquid phase of dusty plasmas also gives access to hydrodynamic phenomena at the individual particle scale.

  15. Using crystal zoning to track crystal mush differentiation (Invited)

    NASA Astrophysics Data System (ADS)

    Humphreys, M.

    2010-12-01

    Exposed plutonic rocks contain clues to the differentiation and fractionation processes that may be operating beneath currently active volcanoes. There is potential to gain insights into phenomena including crystal fractionation, the movement of evolved fluids within a porous crystal mush, the extraction of late-stage melts, and the formation of precious metal deposits. In layered intrusions, attention has commonly focused on bulk magma differentiation, with the differentiation of interstitial liquids remaining in the mush being relatively neglected. However, μm-scale study of minor element zonation in intercumulus overgrowths and interstitial phases can help to understand the intricacies of crystal mush processes. By studying very slowly diffusing elements or components (such as TiO2 or anorthite content) it is possible to essentially eliminate problems relating to diffusive equilibration during prolonged slow cooling, and infer the evolving composition of the residual liquid. For layered intrusions, insights into crystal mush differentiation mechanisms can be obtained by comparing interstitial zoning profiles with the cryptic chemical changes that are observed in primocrysts with increasing stratigraphic height. The Skaergaard Intrusion, east Greenland, formed from essentially a single pulse of magma that solidified by near-perfect fractional crystallisation. The anorthite content (XAn) of the plagioclase primocrysts decreases monotonically with increasing stratigraphic height, as a result of crystallisation at lower temperatures and from increasingly evolved liquids. Ti contents of plagioclase increase systematically with stratigraphic height until cumulus Fe-Ti oxides appear, and then decrease as a result of falling liquid TiO2. However, interstitial Ti zoning follows different trends, which demonstrates that the interstitial and bulk liquids undergo very different liquid lines of descent. Distinct compositional trends develop adjacent to fine-grained, mafic

  16. Resistive switching phenomena: A review of statistical physics approaches

    SciTech Connect

    Lee, Jae Sung; Lee, Shinbuhm; Noh, Tae Won

    2015-08-31

    Here we report that resistive switching (RS) phenomena are reversible changes in the metastable resistance state induced by external electric fields. After discovery ~50 years ago, RS phenomena have attracted great attention due to their potential application in next-generation electrical devices. Considerable research has been performed to understand the physical mechanisms of RS and explore the feasibility and limits of such devices. There have also been several reviews on RS that attempt to explain the microscopic origins of how regions that were originally insulators can change into conductors. However, little attention has been paid to the most important factor in determining resistance: how conducting local regions are interconnected. Here, we provide an overview of the underlying physics behind connectivity changes in highly conductive regions under an electric field. We first classify RS phenomena according to their characteristic current–voltage curves: unipolar, bipolar, and threshold switchings. Second, we outline the microscopic origins of RS in oxides, focusing on the roles of oxygen vacancies: the effect of concentration, the mechanisms of channel formation and rupture, and the driving forces of oxygen vacancies. Third, we review RS studies from the perspective of statistical physics to understand connectivity change in RS phenomena. We discuss percolation model approaches and the theory for the scaling behaviors of numerous transport properties observed in RS. Fourth, we review various switching-type conversion phenomena in RS: bipolar-unipolar, memory-threshold, figure-of-eight, and counter-figure-of-eight conversions. Finally, we review several related technological issues, such as improvement in high resistance fluctuations, sneak-path problems, and multilevel switching problems.

  17. Seasonality of alcohol-related phenomena in Estonia

    NASA Astrophysics Data System (ADS)

    Silm, Siiri; Ahas, Rein

    2005-03-01

    We studied alcohol consumption and its consequences as a seasonal phenomenon in Estonia and analysed the social and environmental factors that may cause its seasonal rhythm. There are two important questions when researching the seasonality of human activities: (1) whether it is caused by natural or social factors, and (2) whether the impact of the factors is direct or indirect. Often the seasonality of social phenomena is caused by social factors, but the triggering mechanisms are related to environmental factors like temperature, precipitation, and radiation via the circannual calendar. The indicators of alcohol consumption in the current paper are grouped as: (1) pre-consumption phenomena, i.e. production, tax and excise, sales (beer, wine and vodka are analysed separately), and (2) post-consumption phenomena, i.e. alcohol-related crime and traffic accidents and the number of people detained in lockups and admitted to alcohol treatment clinics. In addition, seasonal variability in the amount of alcohol advertising has been studied, and a survey has been carried out among 87 students of Tartu University. The analysis shows that different phenomena related to alcohol have a clear seasonal rhythm in Estonia. The peak period of phenomena related to beer is in the summer, from June to August and the low point is during the first months of the year. Beer consumption correlates well with air temperature. The consumption of vodka increases sharply at the end of the year and in June; the production of vodka does not have a significant correlation with negative temperatures. The consumption of wine increases during summer and in December. The consequences of alcohol consumption, expressed as the rate of traffic accidents or the frequency of medical treatment, also show seasonal variability. Seasonal variability of alcohol consumption in Estonia is influenced by natural factors (temperature, humidity, etc.) and by social factors (celebrations, vacations, etc.). However

  18. Resistive switching phenomena: A review of statistical physics approaches

    DOE PAGES

    Lee, Jae Sung; Lee, Shinbuhm; Noh, Tae Won

    2015-08-31

    Here we report that resistive switching (RS) phenomena are reversible changes in the metastable resistance state induced by external electric fields. After discovery ~50 years ago, RS phenomena have attracted great attention due to their potential application in next-generation electrical devices. Considerable research has been performed to understand the physical mechanisms of RS and explore the feasibility and limits of such devices. There have also been several reviews on RS that attempt to explain the microscopic origins of how regions that were originally insulators can change into conductors. However, little attention has been paid to the most important factor inmore » determining resistance: how conducting local regions are interconnected. Here, we provide an overview of the underlying physics behind connectivity changes in highly conductive regions under an electric field. We first classify RS phenomena according to their characteristic current–voltage curves: unipolar, bipolar, and threshold switchings. Second, we outline the microscopic origins of RS in oxides, focusing on the roles of oxygen vacancies: the effect of concentration, the mechanisms of channel formation and rupture, and the driving forces of oxygen vacancies. Third, we review RS studies from the perspective of statistical physics to understand connectivity change in RS phenomena. We discuss percolation model approaches and the theory for the scaling behaviors of numerous transport properties observed in RS. Fourth, we review various switching-type conversion phenomena in RS: bipolar-unipolar, memory-threshold, figure-of-eight, and counter-figure-of-eight conversions. Finally, we review several related technological issues, such as improvement in high resistance fluctuations, sneak-path problems, and multilevel switching problems.« less

  19. Laboratory studies of crystal growth in magma

    NASA Astrophysics Data System (ADS)

    Hammer, J. E.; Welsch, B. T.; First, E.; Shea, T.

    2012-12-01

    The proportions, compositions, and interrelationships among crystalline phases and glasses in volcanic rocks cryptically record pre-eruptive intensive conditions, the timing of changes in crystallization environment, and the devolatilization history of eruptive ascent. These parameters are recognized as important monitoring tools at active volcanoes and interpreting geologic events at prehistoric and remote eruptions, thus motivating our attempts to understand the information preserved in crystals through an experimental appoach. We are performing laboratory experiments in mafic, felsic, and intermediate composition magmas to study the mechanisms of crystal growth in thermochemical environments relevant to volcanic environments. We target features common to natural crystals in igneous rocks for our experimental studies of rapid crystal growth phenomena: (1) Surface curvature. Do curved interfaces and spongy cores represent evidence of dissolution (i.e., are they corrosion features), or do they record the transition from dendritic to polyhedral morphology? (2) Trapped melt inclusions. Do trapped liquids represent bulk (i.e., far-field) liquids, boundary layer liquids, or something intermediate, depending on individual species diffusivity? What sequence of crystal growth rates leads to preservation of sealed melt inclusions? (3) Subgrain boundaries. Natural phenocrysts commonly exhibit tabular subgrain regions distinguished by small angle lattice misorientations or "dislocation lamellae" and undulatory extinction. Might these crystal defects be produced as dendrites undergo ripening? (4) Clusters. Contacting clusters of polymineralic crystals are the building blocks of cumulates, and are ubiquitous features of mafic volcanic rocks. Are plagioclase and clinopyroxene aligned crystallographically, suggesting an epitaxial (surface energy) relationship? (5) Log-normal size distribution. What synthetic cooling histories produce "natural" distributions of crystal sizes, and

  20. Bleaching and micro-cracking phenomena induced in various types of sapphires by keV-electron beam irradiations

    NASA Astrophysics Data System (ADS)

    Lee, Bo-Hyun; Teraji, Tokuyuki; Ito, Toshimichi

    2006-08-01

    Electron-beam-induced phenomena on α-Al 2O 3 single-crystals have been investigated using a scanning electron microscope with a cathodoluminescence (CL) apparatus. Various types of sapphires were irradiated at room temperature by keV electrons of the total fluences up to ≈6 × 10 20 electrons cm -2. In the case of colored specimens, increasing amounts of electron irradiations induced a reversible "bleaching" phenomenon and subsequently an irreversible "cracking" phenomenon on nanometer scales in the surface and subsurface layers. The details of the fluence dependences of these beam-induced changes differed among the various natural and synthetic sapphires. These changes were dramatically reduced by the presence of thin metal layers on the insulating sapphire surfaces, indicating that these phenomena were induced by the presence of charges accumulated in the specimens. Such electron irradiations also varied CL intensities of the F + center peaked at 330 nm while the Cr 3+ center CL peak observed at 697 nm was almost unchanged in intensity with increasing the electron fluence. Furthermore, information on these CL centers along the depth direction from the specimen surface was obtained using variable incident electron energies ranging from 1 to 25 keV. The above phenomena are discussed in relation to the crystalline quality of the specimens examined.

  1. Delusions, illusions and hallucinations in epilepsy: 1. Elementary phenomena.

    PubMed

    Elliott, Brent; Joyce, Eileen; Shorvon, Simon

    2009-08-01

    The purpose of this paper and its pair is to provide a comprehensive review, from the different perspectives of neurology and neuropsychiatry, of the phenomenology and mechanisms of hallucinatory experience in epilepsy. We emphasise the clinical and electrophysiological features, and make comparisons with the primary psychoses. In this paper, we consider definitions and elementary hallucinatory phenomena. Regarding definition, there is a clearly divergent evolution in meaning of the terms delusion, illusion and hallucination in the separate traditions of neurology and psychiatry. Psychiatry makes clear distinctions between the terms and has focussed on the empirical use of descriptive psychopathology in order to delineate the various psychiatric syndromes, including those in epilepsy. These distinctions in psychiatry have stood the test of time and are useful in clinical descriptive terms, but do not help to understand the basic mechanisms. The focus of neurology has been to regard delusions, illusions and hallucinations in epilepsy as a result of localised or network based neuronal epileptic activity that can be investigated especially using intracranial stereoelectroencephalography (SEEG). The neurological approach leads to a more synoptical definition of 'hallucination' than in psychiatry and to the conclusion that there is little point in differentiating hallucination from illusion or delusion in view of the overlap in the physiological bases of the phenomena. The semiologically derived differentiation of these terms in psychiatry is not supported by similarly discrete electrophysiological signatures. However, as discussed in the second paper, some psychotic states are associated with similar electrophysiological changes. The wide range of hallucinatory symptoms occurring during epileptic seizures recorded during intracranial SEEG and brain stimulation are reviewed here, including: experiential and interpretive phenomena, affective symptoms, as well as auditory

  2. Multipoint observations of plasma phenomena made in space by Cluster

    NASA Astrophysics Data System (ADS)

    Goldstein, M. L.; Escoubet, P.; Hwang, K.-Joo; Wendel, D. E.; Viñas, A.-F.; Fung, S. F.; Perri, S.; Servidio, S.; Pickett, J. S.; Parks, G. K.; Sahraoui, F.; Gurgiolo, C.; Matthaeus, W.; Weygand, J. M.

    2015-06-01

    Plasmas are ubiquitous in nature, surround our local geospace environment, and permeate the universe. Plasma phenomena in space give rise to energetic particles, the aurora, solar flares and coronal mass ejections, as well as many energetic phenomena in interstellar space. Although plasmas can be studied in laboratory settings, it is often difficult, if not impossible, to replicate the conditions (density, temperature, magnetic and electric fields, etc.) of space. Single-point space missions too numerous to list have described many properties of near-Earth and heliospheric plasmas as measured both in situ and remotely (see http://www.nasa.gov/missions/#.U1mcVmeweRY for a list of NASA-related missions). However, a full description of our plasma environment requires three-dimensional spatial measurements. Cluster is the first, and until data begin flowing from the Magnetospheric Multiscale Mission (MMS), the only mission designed to describe the three-dimensional spatial structure of plasma phenomena in geospace. In this paper, we concentrate on some of the many plasma phenomena that have been studied using data from Cluster. To date, there have been more than 2000 refereed papers published using Cluster data but in this paper we will, of necessity, refer to only a small fraction of the published work. We have focused on a few basic plasma phenomena, but, for example, have not dealt with most of the vast body of work describing dynamical phenomena in Earth's magnetosphere, including the dynamics of current sheets in Earth's magnetotail and the morphology of the dayside high latitude cusp. Several review articles and special publications are available that describe aspects of that research in detail and interested readers are referred to them (see for example, Escoubet et al. 2005 Multiscale Coupling of Sun-Earth Processes, p. 459, Keith et al. 2005 Sur. Geophys. 26, 307-339, Paschmann et al. 2005 Outer Magnetospheric Boundaries: Cluster Results, Space Sciences Series

  3. Find of anisotropic carbonic matter on a curve-faced diamond crystal

    NASA Astrophysics Data System (ADS)

    Brodskaya, R. L.; Golubev, E. A.; Isaenko, S. I.

    2016-12-01

    The study focuses on the identification and investigation of crystal-optical anisotropy phenomena observed on surfaces of a curve-faced diamond crystal found in alluvial sediments of the Lower Us'va River in Perm territory. Raman spectroscopy and atomic force microscopy show that interference of polarized light reflected from the tetrahexahedral faces of the diamond crystal is inspired by anisotropic carbonic matter, which appears as a film with graphene or nanographite structure and about 4 nm in thickness. The data allow us to suggest the formation conditions of curve-faced diamond crystals and origin of nanocrystalline carbonic matter on their faces.

  4. Sodium chloride precipitation reaction coefficient from crystallization experiment in a microfluidic device

    NASA Astrophysics Data System (ADS)

    Naillon, A.; Joseph, P.; Prat, M.

    2017-04-01

    The crystal growth of sodium chloride from an aqueous solution is studied from evaporation experiments in microfluidic channels in conjunction with analytical and numerical computations. The crystal growth kinetics is recorded using a high speed camera in order to determine the intrinsic precipitation reaction coefficient. The study reveals that the crystal growth rates determined in previous studies are all affected by the ions transport phenomena in the solution and thus not representative of the precipitation reaction. It is suggested that accurate estimate of sodium chloride precipitation reaction coefficient presented here offers new opportunities for a better understanding of important issues involved in the damages of porous materials induced by the salt crystallization.

  5. Super-crystals in composite ferroelectrics

    PubMed Central

    Pierangeli, D.; Ferraro, M.; Di Mei, F.; Di Domenico, G.; de Oliveira, C. E. M.; Agranat, A. J.; DelRe, E.

    2016-01-01

    As atoms and molecules condense to form solids, a crystalline state can emerge with its highly ordered geometry and subnanometric lattice constant. In some physical systems, such as ferroelectric perovskites, a perfect crystalline structure forms even when the condensing substances are non-stoichiometric. The resulting solids have compositional disorder and complex macroscopic properties, such as giant susceptibilities and non-ergodicity. Here, we observe the spontaneous formation of a cubic structure in composite ferroelectric potassium–lithium–tantalate–niobate with micrometric lattice constant, 104 times larger than that of the underlying perovskite lattice. The 3D effect is observed in specifically designed samples in which the substitutional mixture varies periodically along one specific crystal axis. Laser propagation indicates a coherent polarization super-crystal that produces an optical X-ray diffractometry, an ordered mesoscopic state of matter with important implications for critical phenomena and applications in miniaturized 3D optical technologies. PMID:26907725

  6. The function of nonlinear phenomena in meerkat alarm calls.

    PubMed

    Townsend, Simon W; Manser, Marta B

    2011-02-23

    Nonlinear vocal phenomena are a ubiquitous feature of human and non-human animal vocalizations. Although we understand how these complex acoustic intrusions are generated, it is not clear whether they function adaptively for the animals producing them. One explanation is that nonlinearities make calls more unpredictable, increasing behavioural responses and ultimately reducing the chances of habituation to these call types. Meerkats (Suricata suricatta) exhibit nonlinear subharmonics in their predator alarm calls. We specifically tested the 'unpredictability hypothesis' by playing back naturally occurring nonlinear and linear medium-urgency alarm call bouts. Results indicate that subjects responded more strongly and foraged less after hearing nonlinear alarm calls. We argue that these findings support the unpredictability hypothesis and suggest this is the first study in animals or humans to show that nonlinear vocal phenomena function adaptively.

  7. Sixth Microgravity Fluid Physics and Transport Phenomena Conference Abstracts

    NASA Technical Reports Server (NTRS)

    Singh, Bhim (Compiler)

    2002-01-01

    The Sixth Microgravity Fluid Physics and Transport Phenomena Conference provides the scientific community the opportunity to view the current scope of the Microgravity Fluid Physics and Transport Phenomena Program, current research opportunities, and plans for the near future. The conference focuses not only on fundamental research but also on applications of this knowledge towards enabling future space exploration missions. A whole session dedicated to biological fluid physics shows increased emphasis that the program has placed on interdisciplinary research. The conference includes invited plenary talks, technical paper presentations, poster presentations, and exhibits. This TM is a compilation of abstracts of the papers and the posters presented at the conference. Web-based proceedings, including the charts used by the presenters, will be posted on the web shortly after the conference.

  8. A Brief Survey of Activity Phenomena in Cosmic Objects

    NASA Astrophysics Data System (ADS)

    Harutyunian, H. A.

    2016-06-01

    An attempt is done to unify the variety of physical active phenomena observed in various cosmic objects belonging to the all hierarchical levels. The dark energy carrier is suggested to interact with the baryonic matter and provide the activity energy through the injection from "the main reservoir". The concept that the Hubble flow is not possible for non-cosmological shorter scales where the baryonic objects are believed to be gravitationally bound is considered in a few words to show that it is a simple extrapolation of the a priori hypothesis on the formation of cosmic objects. Some observational facts are pointed to show that expansion phenomena at shorter scales could be explained using the Hubble law only. The physical consequences of dark energy exchange with the atomic nuclei and "gravitationally bound" objects are considered.

  9. High spatial resolution measurements of ram accelerator gas dynamic phenomena

    NASA Technical Reports Server (NTRS)

    Hinkey, J. B.; Burnham, E. A.; Bruckner, A. P.

    1992-01-01

    High spatial resolution experimental tube wall pressure measurements of ram accelerator gas dynamic phenomena are presented. The projectile resembles the centerbody of a ramjet and travels supersonically through a tube filled with a combustible gaseous mixture, with the tube acting as the outer cowling. Pressure data are recorded as the projectile passes by sensors mounted in the tube wall at various locations along the tube. Data obtained by using a special highly instrumented section of tube has allowed the recording of gas dynamic phenomena with a spatial resolution on the order of one tenth the projectile length. High spatial resolution tube wall pressure data from the three regimes of propulsion studied to date (subdetonative, transdetonative, and superdetonative) are presented and reveal the 3D character of the flowfield induced by projectile fins and the canting of the projectile body relative to the tube wall. Also presented for comparison to the experimental data are calculations made with an inviscid, 3D CFD code.

  10. Autoscopic phenomena and one's own body representation in dreams.

    PubMed

    Occhionero, Miranda; Cicogna, Piera Carla

    2011-12-01

    Autoscopic phenomena (AP) are complex experiences that include the visual illusory reduplication of one's own body. From a phenomenological point of view, we can distinguish three conditions: autoscopic hallucinations, heautoscopy, and out-of-body experiences. The dysfunctional pattern involves multisensory disintegration of personal and extrapersonal space perception. The etiology, generally either neurological or psychiatric, is different. Also, the hallucination of Self and own body image is present during dreams and differs according to sleep stage. Specifically, the representation of the Self in REM dreams is frequently similar to the perception of Self in wakefulness, whereas in NREM dreams, a greater polymorphism of Self and own body representation is observed. The parallels between autoscopic phenomena in pathological cases and the Self-hallucination in dreams will be discussed to further the understanding of the particular states of self awareness, especially the complex integration of different memory sources in Self and body representation.

  11. Modelling the mass migration phenomena in partially frozen heat pipes

    SciTech Connect

    Keddy, M.D.; Merrigan, M.A.; Critchley, E.

    1993-11-01

    Liquid metal heat pipes operated at power throughputs well below their design point and with sink temperatures below the freezing temperature of the working fluid may fail as a result of the working fluid migrating to a cold region within the pipe, freezing there, and not returning to the evaporator section. Eventually, sufficient working fluid inventory may be lost to the cold region to cause a local dry-out condition in the evaporator. A joint experimental and analytical effort by the Air Force Phillips Laboratory and Los Alamos National Laboratory is underway to investigate this phenomena. This paper presents an analytical model developed to describes this phenomena. The model provides for analytic determination of heat pipe temperature profiles, freeze-front locations and mass migration rates.

  12. Ecological momentary assessment (EMA) of depression-related phenomena.

    PubMed

    Armey, Michael F; Schatten, Heather T; Haradhvala, Natasha; Miller, Ivan W

    2015-08-01

    Ecological momentary assessment (EMA) is one research method increasingly employed to better understand the processes that underpin depression and related phenomena. In particular, EMA is well suited to the study of affect (e.g., positive and negative affect), affective responses to stress (e.g., emotion reactivity), and behaviors (e.g., activity level, sleep) that are associated with depression. Additionally, EMA can provide insights into self-harm behavior (i.e. suicide and non-suicidal self-injury), and other mood disorders (e.g. bipolar disorder) commonly associated with depressive episodes. Given the increasing availability and affordability of handheld computing devices such as smartphones, EMA is likely to play an increasingly important role in the study of depression and related phenomena in the future.

  13. Exploiting transient phenomena for imaging with breath figures

    NASA Astrophysics Data System (ADS)

    Sasikumar, Harish; Varma, Manoj M.

    2017-02-01

    Breath figures refer to the patterns formed when vapor condenses into the liquid phase on a surface, revealing heterogeneities in topography or chemical composition. These figures are composed of micro-droplets, which scatter light and produce optical contrast. Differences in hydrophobicity imposed by surface features or contaminants result in a difference in micro-droplet densities, which has been used in applications such as substrate independent optical visualization of single layer graphene flakes. Here, we show that transient phenomena, such as the pinning transition of micro-droplets condensed over a polymer surface, can be used to enhance the optical contrast even when the time averaged difference in micro-droplet densities is not substantial. Thus, this work opens a new way of visualizing surface heterogeneities using transient phenomena occurring during condensation or evaporation of micro-droplets as opposed to only using time averaged differences in wettability due to the surface features.

  14. Phenomena associated with magma expansion into a drift

    SciTech Connect

    Gaffney, E. S.

    2002-01-01

    One of the significant threats to the proposed Yucca Mountain nuclear waste repository has been identified as the possibility of intersection of the underground structure by a basaltic intrusion. Based on the geology of the region, it is assumed that such an intrusion would consist of an alkali basalt similar to the nearby Lathrop Wells cone, which has been dated at about 78 ka. The threat of radioactive release may be either from eruption through the surface above the repository of basalt that had been contaminated or from migration through ground water of radionucleides released as a result of damage to waste packages that interact with the magma. As part of our study of these threats, we are analyzing the phenomena associated with magma expansion into drifts in tuff. The early phenomena of the encounter of volatile-rich basaltic magma with a drift are discussed here.

  15. Expert- Demonstrating Reentry Aerothermodinamics Phenomena From A System Perspective

    NASA Astrophysics Data System (ADS)

    Massobrio, F.; Passarelli, G.; Gavira-Izquierdo, J.; Ratti, F.

    2011-05-01

    EXPERT is developed by the European Space Agency (ESA) in order to provide the scientific community with quality data on critical aero-thermodynamic phenomena encountered during hypersonic flights as well as to provide industry with system experience of re-entry vehicle manufacturing and development of hypersonic instrumentation. EXPERT is equipped with 14 experiments provided by several scientific institutions all around Europe. The experiments address major aerothermodinamics phenomena: TPS material characterization, surface catalysis and oxidation, plasma spectroscopy, laminar to turbulent transition, flow separation and reattachment, shock-boundary layer interactions, base flow characteristic and aerodynamic characterization of flap control surfaces. The paper focus on the status of the EXPERT project: the design activities and the on going manufacturing, the main challenges and the expected flight data results. EXPERT will benefit future atmospheric re- entry activities ranging from cargo to human orbital transportation systems as well as re-usable launchers and scientific probes.

  16. The function of nonlinear phenomena in meerkat alarm calls

    PubMed Central

    Townsend, Simon W.; Manser, Marta B.

    2011-01-01

    Nonlinear vocal phenomena are a ubiquitous feature of human and non-human animal vocalizations. Although we understand how these complex acoustic intrusions are generated, it is not clear whether they function adaptively for the animals producing them. One explanation is that nonlinearities make calls more unpredictable, increasing behavioural responses and ultimately reducing the chances of habituation to these call types. Meerkats (Suricata suricatta) exhibit nonlinear subharmonics in their predator alarm calls. We specifically tested the ‘unpredictability hypothesis’ by playing back naturally occurring nonlinear and linear medium-urgency alarm call bouts. Results indicate that subjects responded more strongly and foraged less after hearing nonlinear alarm calls. We argue that these findings support the unpredictability hypothesis and suggest this is the first study in animals or humans to show that nonlinear vocal phenomena function adaptively. PMID:20659926

  17. Reducing spurious flow in simulations of electrokinetic phenomena

    NASA Astrophysics Data System (ADS)

    Rempfer, Georg; Davies, Gary B.; Holm, Christian; de Graaf, Joost

    2016-07-01

    Electrokinetic transport phenomena can strongly influence the behaviour of macromolecules and colloidal particles in solution, with applications in, e.g., DNA translocation through nanopores, electro-osmotic flow in nanocapillaries, and electrophoresis of charged macromolecules. Numerical simulations are an important tool to investigate these electrokinetic phenomena, but are often plagued by spurious fluxes and spurious flows that can easily exceed physical fluxes and flows. Here, we present a method that reduces one of these spurious currents, spurious flow, by several orders of magnitude. We demonstrate the effectiveness and generality of our method for both the electrokinetic lattice-Boltzmann and finite-element-method based algorithms by simulating a charged sphere in an electrolyte solution and flow through a nanopore. We also show that previous attempts to suppress these spurious currents introduce other sources of error.

  18. Numerical simulation on snow melting phenomena by CIP method

    NASA Astrophysics Data System (ADS)

    Mizoe, H.; Yoon, Seong Y.; Josho, M.; Yabe, T.

    2001-04-01

    A numerical scheme based on the C-CUP method to simulate melting phenomena in snow is proposed. To calculate these complex phenomena we introduce the phase change, elastic-plastic model, porous model, and verify each model by using some simple examples. This scheme is applied to a practical model, such as the snow piled on the insulator of electrical transmission line, in which snow is modeled as a compound material composed of air, water, and ice, and is calculated by elastic-plastic model. The electric field between two electrodes is solved by the Poisson equation giving the Joule heating in the energy conservation that eventually leads to snow melting. Comparison is made by changing the fraction of water in the snow to see its effect on melting process for the cases of applied voltage of 50 and 500 kV on the two electrodes.

  19. Concepts and methods for describing critical phenomena in fluids

    NASA Technical Reports Server (NTRS)

    Sengers, J. V.; Sengers, J. M. H. L.

    1977-01-01

    The predictions of theoretical models for a critical-point phase transistion in fluids, namely the classical equation with third-degree critical isotherm, that with fifth-degree critical isotherm, and the lattice gas, are reviewed. The renormalization group theory of critical phenomena and the hypothesis of universality of critical behavior supported by this theory are discussed as well as the nature of gravity effects and how they affect cricital-region experimentation in fluids. The behavior of the thermodynamic properties and the correlation function is formulated in terms of scaling laws. The predictions of these scaling laws and of the hypothesis of universality of critical behavior are compared with experimental data for one-component fluids and it is indicated how the methods can be extended to describe critical phenomena in fluid mixtures.

  20. Dispersion phenomena in helical flow in a concentric annulus.

    PubMed

    Song, Young Seok; Brenner, Howard

    2009-12-14

    We examined dispersion phenomena of solutes in helical flow in a concentric annulus through a multiscale approach. The helical flow was developed by the combination of the Poiseuille flow and Couette flow. Here, we present an analytic model that can address the multidimensional Taylor dispersion in the helical flow under a lateral field of thermophoresis (or thermal diffusion) in the gapwise direction. Macroscopic parameters including the average solute velocity and dispersivity were analyzed using relevant microscopic physicochemical properties. The mathematically obtained results were validated by the numerical simulation carried out in this study. The findings show that macrotransport processes are robust and straightforward to handle multidimensional dispersion phenomena of solutes in helical flow. This study is expected to provide a theoretical platform for applications of helical flow such as tube exchangers, oil drilling, and multidimensional field flow fractionations (e.g., helical flow field flow fractionation).

  1. Phenomena of awareness in dementia: heterogeneity and its implications.

    PubMed

    Marková, Ivana S; Clare, Linda; Whitaker, Christopher J; Roth, Ilona; Nelis, Sharon M; Martyr, Anthony; Roberts, Judith L; Woods, Robert T; Morris, Robin

    2014-04-01

    Despite much research on the relationship between awareness and dementia little can be concluded concerning their relationship and the role of other factors. It is likely that studies capture different phenomena of awareness. This study aimed at identifying and delineating such variation by analysing data from three questionnaires obtained during the longitudinal study of awareness in 101 people with early-stage dementia. The data concerned awareness in relation to memory, activities of daily living and socio-emotional function. Significant differences in patterns of discrepancies were obtained. This suggests that the awareness phenomena involved were structurally different; and that, in turn, this may reflect variation in the intrinsic linking between awareness and its 'object' (different 'objects' determining different kinds of judgements). The identification of such differences is necessary so that appropriate methodologies can be applied to the study of awareness in different contexts.

  2. A theoretical study on critical phenomena of magnetic soft modes

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaoyan; Yang, Guohong; Yan, Ming

    2017-02-01

    Below a threshold magnetic field, domain structures in ferromagnetic samples may start to nucleate from the initially saturated state via either continuous or discontinuous phase transitions. Such processes are usually accompanied by the occurrence of soft spin-wave modes at the critical point. In this paper, we present a theoretical study on the critical phenomena of uniform soft modes in a macrospin model and spatially non-uniform ones in ferromagnetic thin films. The critical exponents of the mode frequency and its polarization are derived. The value is found to be equal to one half, which is directly related to the breaking of a reflection-symmetry in the phase transition. At the critical point, the soft mode becomes linearly polarized, which provides an additional measurable effect of the critical phenomena.

  3. Autoscopic phenomena: case report and review of literature

    PubMed Central

    2011-01-01

    Background Autoscopic phenomena are psychic illusory visual experiences consisting of the perception of the image of one's own body or face within space, either from an internal point of view, as in a mirror or from an external point of view. Descriptions based on phenomenological criteria distinguish six types of autoscopic experiences: autoscopic hallucination, he-autoscopy or heautoscopic proper, feeling of a presence, out of body experience, negative and inner forms of autoscopy. Methods and results We report a case of a patient with he-autoscopic seizures. EEG recordings during the autoscopic experience showed a right parietal epileptic focus. This finding confirms the involvement of the temporo-parietal junction in the abnormal body perception during autoscopic phenomena. We discuss and review previous literature on the topic, as different localization of cortical areas are reported suggesting that out of body experience is generated in the right hemisphere while he-autoscopy involves left hemisphere structures. PMID:21219608

  4. Tank Pressure Control Experiment/thermal Phenomena (TPCE/TP)

    NASA Technical Reports Server (NTRS)

    Hasan, M. M.; Knoll, R. H.

    1992-01-01

    The 'Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP)' is a reflight of the tank pressure control experiment (TPCE), flown on STS-43 in a standard Get-Away Special (GAS) container in August 1991. The TPCE obtained extensive video and digital data of the jet induced mixing process in a partially filled tank in low gravity environments. It also provided limited data on the thermal processes involved. The primary objective of the reflight of TPCE is to investigate experimentally the phenomena of liquid superheating and pool nucleate boiling at very low heat fluxes in a long duration low gravity environment. The findings of this experiment will be of direct relevance to space based subcritical cryogenic fluid system design and operation. Experiment hardware and results from the first TPCE are described in outline and graphic form.

  5. Some problems in coupling solar activity to meteorological phenomena

    NASA Technical Reports Server (NTRS)

    Dessler, A. J.

    1975-01-01

    The development of a theory of coupling of solar activity to meteorological phenomena is hindered by the difficulties of devising a mechanism that can modify the behavior of the troposphere while employing only a negligible amount of energy compared with the energy necessary to drive the normal meteorological system, and determining how such a mechanism can effectively couple some relevant magnetospheric process into the troposphere in such a way as to influence the weather. A clue to the nature of the interaction between the weather and solar activity might be provided by the fact that most solar activity undergoes a definite 11-yr cycle, and meteorological phenomena undergo either no closely correlated variation, an 11-yr variation, or a 22-yr variation.

  6. Some problems in coupling solar activity to meteorological phenomena

    NASA Technical Reports Server (NTRS)

    Dessler, A. J.

    1974-01-01

    The development of a theory of coupling of solar activity to meteorological phenomena has to date foundered on the two difficulties of (1) devising a mechanism that can modify the behavior of the troposphere while employing only a negligible amount of energy compared with the energy necessary to drive the normal meteorological system; and (2) determining how such a mechanism can effectively couple some relevant magnetospheric process into the troposphere in such a way as to influence the weather. A clue to the nature of the interaction between the weather and solar activity might be provided by the fact that most solar activity undergoes a definite 11-year cycle, while meteorological phenomena undergo either no closely correlated variation, or an 11-year variation, or a 22-year variation.

  7. Swimming photochromic azobenzene single crystals in triacrylate solution.

    PubMed

    Milam, Kenneth; O'Malley, Garrett; Kim, Namil; Golovaty, Dmitry; Kyu, Thein

    2010-06-17

    Self-motion of a growing single crystal of azobenzene chromophore in triacrylate solution (TA) is investigated in relation to the solid-liquid phase diagram bound by the solidus and liquidus lines. Upon thermal quenching from the isotropic melt to the crystal + liquid gap, various single crystals develop in a manner dependent on concentration and supercooling depth. During the crystal growth, TA solvent is rejected from the growing faceted fronts, enriching with TA in close proximity to the crystal-solution interface. The concentration gradient that formed as the result of TA expulsion induces convective flows in the solution and generates spatial variability of surface tension usually responsible for Marangoni effect. Either or both of these phenomena may have contributed to the observed self-motion including swimming, sinking, and floating of the azobenzene rhomboidal crystal in TA solution. A stationary rhomboidal crystal is also shown to swim upon irradiation with the UV light because of a mechanical torque generated by the trans-cis isomerization. Judging from the sinking or floating behavior of the azobenzene crystal, it may be inferred that the nucleation occurs at the solution-air interface.

  8. Molecular Dynamics Simulations of Spinodal-Assisted Polymer Crystallization

    SciTech Connect

    Gee, R H; Lacevic, N M; Fried, L

    2005-07-08

    Large scale molecular dynamics simulations of bulk melts of polar (poly(vinylidene fluoride) (pVDF)) polymers are utilized to study chain conformation and ordering prior to crystallization under cooling. While the late stages of polymer crystallization have been studied in great detail, recent theoretical and experimental evidence indicates that there are important phenomena occurring in the early stages of polymer crystallization that are not understood to the same degree. When the polymer melt is quenched from a temperature above the melting temperature to the crystallization temperature, crystallization does not occur instantaneously. This initial interval without crystalline order is characterized as an induction period. It has been thought of as a nucleation period in the classical theories of polymer crystallization, but recent experiments, computer simulations, and theoretical work suggest that the initial period in polymer crystallization is assisted by a spinodal decomposition type mechanism. In this study we have achieved physically realistic length scales to study early stages of polymer ordering, and show that spinodal-assisted ordering prior to crystallization is operative in polar polymers suggesting general applicability of this process.

  9. Crystallization Behavior of M97 Series Silicone Cushions

    SciTech Connect

    Chien, A.; DeTeresa, S.; Cohenour, R.; Schnieder, J.; LeMay, J.; Balazs, B.

    2000-09-07

    M97 series siloxanes are poly(dimethyl-diphenyl) siloxanes that are reinforced through a mixture of precipitated and fumed silica fillers which are blended in through the addition of a short chain polydimethylsiloxane processing aid. M97 silicones exhibit crystallization at -80.25 C by thermal (modulated differential scanning calorimetry) and mechanical (dynamic mechanical analysis) techniques. Isothermal dynamic mechanical analysis experiments illustrated that crystallization occurred over a 1.8 hour period in silica-filled systems and 2.8 hours in unfilled systems. The onset of crystallization typically occurred after a 30 minute incubation/nucleation period. {gamma}-radiation caused the crystallization rate to decrease proportionally with dosage, but did not decrease the amount of crystallization that ultimately occurred. Irradiation in vacuum resulted in slower overall crystallization rates compared to air irradiation due to increased crosslinking of the polymer matrix under vacuum. Modulated differential scanning calorimetry contrasted the crystallization and melting behavior of pure PDMS versus the M97 base polymer and helped determine which component of the composite was the origin of the crystallization phenomena.

  10. Frustration of crystallisation by a liquid-crystal phase.

    PubMed

    Syme, Christopher D; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-02-17

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being "in between" the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids.

  11. Bringing Together Computational and Experimental Capabilities at the Crystal Scale

    SciTech Connect

    Barton, N R; Bernier, J V; Edmiston, J K

    2009-07-23

    Many phenomena of interest occur at the scale of crystals or are controlled be events happening at the crystalline scale. Examples include allotropic phase transformations in metals and pore collapse in energetic crystals. The research community is increasingly able to make detailed experimental observations at the crystalline scale and to inform crystal scale models using lower length scale computational tools. In situ diffraction techniques are pushing toward finer spatial and temporal resolution. Molecular and dislocation dynamics calculations are now able to directly inform mechanisms at the crystalline scale. Taken together, these factors give crystal based continuum models the ability to rationalize experimental observations, investigate competition among physical processes, and, when appropriately formulated and calibrated, predict behaviors. We will present an overview of current efforts, with emphasis on recent work investigating phase transformations and twinning in metals.

  12. Shear effects on crystal nucleation in colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Cerdà, Juan J.; Sintes, Tomás; Holm, C.; Sorensen, C. M.; Chakrabarti, A.

    2008-09-01

    Extensive two-dimensional Langevin dynamics simulations are used to determine the effect of steady shear flows on the crystal nucleation kinetics of charge stabilized colloids and colloids whose pair potential possess an attractive shallow well of a few kBT ’s (attractive colloids). Results show that in both types of systems small amounts of shear speeds up the crystallization process and enhances the quality of the growing crystal significantly. Moderate shear rates, on the other hand, destroy the ordering in the system. The very high shear rate regime where a reentering transition to the ordered state could exist is not considered in this work. In addition to the crystal nucleation phenomena, the analysis of the transport properties and the characterization of the steady state regime under shear are performed.

  13. Frustration of crystallisation by a liquid–crystal phase

    PubMed Central

    Syme, Christopher D.; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-01-01

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being “in between” the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids. PMID:28209972

  14. Self-force on dislocation segments in anisotropic crystals.

    PubMed

    Fitzgerald, S P; Aubry, S

    2010-07-28

    A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 °C.

  15. Hgi2 Sub 2 Crystal Growth for Nuclear Detectors

    NASA Technical Reports Server (NTRS)

    Schnepple, W. F.; Vandenberg, L.

    1985-01-01

    The objectives of this program are to obtain a benchmark quality sample grown at low-g conditions and to study vapor growth phenomena under space conditions. Ground-based crystals show a defect structure which impairs their performance as nuclear radiation detectors. These defects may be caused by the gravitational force acting on the crystal in its weakended state at the elevated growth temperature and by irregular convection patterns in the vapor during growth. Mechanical strength measurements have been performed (uniaxial compression tests) which show that the crystals exhibit slip parallel to the c-planes at stresses as low as 1/2 psi. Preliminary calculations using a simple linearized model indicate the oscillating instabilities in the convection part of the vapor transport system are unlikely, even at 1-g, provided that the utmost care is taken in the preparation of the crystal growth source material.

  16. Frustration of crystallisation by a liquid–crystal phase

    NASA Astrophysics Data System (ADS)

    Syme, Christopher D.; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-02-01

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being “in between” the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids.

  17. The hard start phenomena in hypergolic engines. Volume 1: Bibliography

    NASA Technical Reports Server (NTRS)

    Miron, Y.; Perlee, H. E.

    1974-01-01

    A bibliography of reports pertaining to the hard start phenomenon in attitude control rocket engines on Apollo spacecraft is presented. Some of the subjects discussed are; (1) combustion of hydrazine, (2) one dimensional theory of liquid fuel rocket combustion, (3) preignition phenomena in small pulsed rocket engines, (4) experimental and theoretical investigation of the fluid dynamics of rocket combustion, and (5) nonequilibrium combustion and nozzle flow in propellant performance.

  18. Search for Higgs and new phenomena at colliders

    SciTech Connect

    Lammel, Stephan; /Fermilab

    2006-01-01

    The present status of searches for the Higgs boson(s) and new phenomena is reviewed. The focus is on analyses and results from the current runs of the HERA and Tevatron experiments. The LEP experiments have released their final combined MSSM Higgs results for this conference. Also included are results from sensitivity studies of the LHC experiments and lepton flavor violating searches from the B factories, KEKB and PEP-II.

  19. The Modeling of Chemical Phenomena Using Topological Indices.

    DTIC Science & Technology

    1987-03-06

    isomer*degeneracy, fil will always be equal to the number of isomers. The range of applicability ofn C is thus strictly limited. To overcome the... applications in the biological sphere are referred to appropriate review articles [46,471. indices have been employed in correlations with a large number of...Chemical Phenomena Using ______________ Topological Indices 4. PERFORMING ORG. REPORT MUMMER 7. AUTHOR(e) I. CON4TRACT OR GRANT NUMBER ~e) D.H. Rouvray 9

  20. Recent Applications of the Volterra Theory to Aeroelastic Phenomena

    NASA Technical Reports Server (NTRS)

    Silva, Walter A.; Haji, Muhammad R; Prazenica, Richard J.

    2005-01-01

    The identification of nonlinear aeroelastic systems based on the Volterra theory of nonlinear systems is presented. Recent applications of the theory to problems in experimental aeroelasticity are reviewed. These results include the identification of aerodynamic impulse responses, the application of higher-order spectra (HOS) to wind-tunnel flutter data, and the identification of nonlinear aeroelastic phenomena from flight flutter test data of the Active Aeroelastic Wing (AAW) aircraft.

  1. General theory of Taylor dispersion phenomena. Part 3. Surface transport

    SciTech Connect

    Dill, L.H.; Brenner, H.

    1982-01-01

    An asymptotic theory of Brownian tracer particle transport phenomena within a bulk fluid, as augmented by surface transport, is presented in the context of generalized Taylor dispersion theory. The analysis expands upon prior work, which was limited to transport wholly within a continuous phase, so as to now include surface adsorption, diffusion, and convection of the tracer along a continuous surface bounding the continuous fluid phase.

  2. Heliospheric Consecuences of Solar Activity In Several Interplanetary Phenomena

    NASA Astrophysics Data System (ADS)

    Valdés-Galicia, J. F.; Mendoza, B.; Lara, A.; Maravilla, D.

    We have done an analysis of several phenomena related to solar activity such as the total magnetic flux, coronal hole area and sunspots, investigated its long trend evolu- tion over several solar cycles and its possible relationships with interplanetary shocks, sudden storm commencements at earth and cosmic ray variations. Our results stress the physical connection between the solar magnetic flux emergence and the interplan- etary medium dynamics, in particular the importance of coronal hole evolution in the structuring of the heliosphere.

  3. Transient Phenomena in Gene Expression after Induction of Transcription

    PubMed Central

    Deneke, Carlus; Rudorf, Sophia; Valleriani, Angelo

    2012-01-01

    When transcription of a gene is induced by a stimulus, the number of its mRNA molecules changes with time. Here we discuss how this time evolution depends on the shape of the mRNA lifetime distribution. Analysis of the statistical properties of this change reveals transient effects on polysomes, ribosomal profiles, and rate of protein synthesis. Our studies reveal that transient phenomena in gene expression strongly depend on the specific form of the mRNA lifetime distribution. PMID:22558114

  4. Fourth DOE Natural Phenomena Hazards Mitigation Conference: Proceedings. Volume 1

    SciTech Connect

    Not Available

    1993-12-31

    This conference allowed an interchange in the natural phenomena area among designers, safety professionals, and managers. The papers presented in Volume I of the proceedings are from sessions I - VIII which cover the general topics of: DOE standards, lessons learned and walkdowns, wind, waste tanks, ground motion, testing and materials, probabilistic seismic hazards, risk assessment, base isolation and energy dissipation, and lifelines and floods. Individual papers are indexed separately. (GH)

  5. Possible relationships between solar activity and meteorological phenomena

    NASA Technical Reports Server (NTRS)

    Bandeen, W. R. (Editor); Maran, S. P. (Editor)

    1975-01-01

    A symposium was conducted in which the following questions were discussed: (1) the evidence concerning possible relationships between solar activity and meteorological phenomena; (2) plausible physical mechanisms to explain these relationships; and (3) kinds of critical measurements needed to determine the nature of solar/meteorological relationships and/or the mechanisms to explain them, and which of these measurements can be accomplished best from space.

  6. Flow phenomena on plates and airfoils of short span

    NASA Technical Reports Server (NTRS)

    Winter, H

    1936-01-01

    Investigations on the flow phenomena at plates and cambered models were carried out with the aid of force measurements, some pressure distribution measurements, and photographic observation. The experimental methods are described and the results given. Section III of this work gives a comprehensive account of the results and enables us to see how nearly the lift line and lift surface theories agree with the experimental results.

  7. Prediction of fading phenomena in land-satellite communication links

    NASA Astrophysics Data System (ADS)

    Blaunstein, N.; Cohen, Y.; Hayakawa, M.

    2010-12-01

    This paper addresses the problem of prediction of probability of successful radio communication of any mobile or stationary subscriber located in areas of service such as complex urban environments characterized by nonline-of-sight propagation conditions, which limit GPS, Low Earth Orbit, and Medium Earth Orbit services in land-satellite communications. It presents a self-consistent physical-statistical approach for predicting fading phenomena usually occurring in land-satellite communication links caused by influence of the terrain features on radio signal propagation from the ground-based to the satellite antenna. This approach combines (1) the statistical description of the buildings array located on the rough terrain and the buildings' overlay profile, based on special probabilistic distributions of built-up terrain parameters, and (2) the theoretical description of propagation phenomena, taking into account multiple scattering, reflection, and diffraction mechanisms. A new technique is proposed for predicting the probability of fading phenomena occurring in land-satellite links using the so-called stochastic multiparametric model. Results of theoretical predictions are compared with those obtained from the "pure statistical" Lutz model and physical-statistical Saunders-Evans model, and then with experimental data obtained for different European cities. Obtained results show that the proposed stochastic approach can be used as a good predictor of fading phenomena in land-satellite communication links for different satellite constellation scenarios and elevations of satellites during their movement surrounding the Earth, with respect to the ground-based antenna for different land environments: rural, mixed residential, suburban, and urban.

  8. Structure for identifying, locating and quantifying physical phenomena

    DOEpatents

    Richardson, John G.

    2006-10-24

    A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A minimum resolvable distance along the structure is selected and a quantity of laterally adjacent conductors is determined. Each conductor includes a plurality of segments coupled in series which define the minimum resolvable distance along the structure. When a deformation occurs, changes in the defined energy transmission characteristics along each conductor are compared to determine which segment contains the deformation.

  9. Investigation of mesoscale meteorological phenomena as observed by geostationary satellite

    NASA Technical Reports Server (NTRS)

    Brundidge, K. C.

    1982-01-01

    Satellite imagery plus conventional synoptic observations were used to examine three mesoscale systems recently observed by the GOES-EAST satellite. The three systems are an arc cloud complex (ACC), mountain lee wave clouds and cloud streets parallel to the wind shear. Possible gravity-wave activity is apparent in all three cases. Of particular interest is the ACC because of its ability to interact with other mesoscale phenomena to produce or enhance convection.

  10. Diffraction phenomena in elastic scattering of heavy ions

    SciTech Connect

    Kotlyar, V.V.; Shebeko, A.V.

    1981-08-01

    Nuclear diffraction phenomena in elastic scattering of heavy ions are studied in the intermediate energy range. Examination is carried out using the strong absorption models for the S-matrix in the angular momentum representation. New asymptotic expressions for the diffraction scattering amplitudes are obtained. The main attention is paid to the study of the relation between the Fresnel and the Fraunhofer parts of the amplitudes obtained in different regions of scattering angles.

  11. The role of spinning electrons in paramagnetic phenomena

    NASA Technical Reports Server (NTRS)

    Bose, D. M.

    1986-01-01

    An attempt is made to explain paramagnetic phenomena without assuming the orientation of a molecule or ion in a magnetic field. Only the spin angular momentum is assumed to be responsible. A derivative of the Gurie-Langevin law and the magnetic moments of ions are given as a function of the number of electrons in an inner, incomplete shell. An explanation of Gerlach's experiments with iron and nickel vapors is attempted. An explanation of magnetomechanical experiments with ferromagne elements is given.

  12. Analysis of phase distribution phenomena in microgravity environments

    NASA Technical Reports Server (NTRS)

    Lahey, Richard T., Jr.; Bonetto, F.

    1994-01-01

    The purpose of the research presented in this paper is to demonstrate the ability of multidimensional two-fluid models for bubbly two-phase flow to accurately predict lateral phase distribution phenomena in microgravity environments. If successful, this research should provide NASA with mechanistically-based analytical methods which can be used for multiphase space system design and evaluation, and should be the basis for future shuttle experiments for model verification.

  13. Computer modelling of nanoscale diffusion phenomena at epitaxial interfaces

    NASA Astrophysics Data System (ADS)

    Michailov, M.; Ranguelov, B.

    2014-05-01

    The present study outlines an important area in the application of computer modelling to interface phenomena. Being relevant to the fundamental physical problem of competing atomic interactions in systems with reduced dimensionality, these phenomena attract special academic attention. On the other hand, from a technological point of view, detailed knowledge of the fine atomic structure of surfaces and interfaces correlates with a large number of practical problems in materials science. Typical examples are formation of nanoscale surface patterns, two-dimensional superlattices, atomic intermixing at an epitaxial interface, atomic transport phenomena, structure and stability of quantum wires on surfaces. We discuss here a variety of diffusion mechanisms that control surface-confined atomic exchange, formation of alloyed atomic stripes and islands, relaxation of pure and alloyed atomic terraces, diffusion of clusters and their stability in an external field. The computational model refines important details of diffusion of adatoms and clusters accounting for the energy barriers at specific atomic sites: smooth domains, terraces, steps and kinks. The diffusion kinetics, integrity and decomposition of atomic islands in an external field are considered in detail and assigned to specific energy regions depending on the cluster stability in mass transport processes. The presented ensemble of diffusion scenarios opens a way for nanoscale surface design towards regular atomic interface patterns with exotic physical features.

  14. Preface: cardiac control pathways: signaling and transport phenomena.

    PubMed

    Sideman, Samuel

    2008-03-01

    Signaling is part of a complex system of communication that governs basic cellular functions and coordinates cellular activity. Transfer of ions and signaling molecules and their interactions with appropriate receptors, transmembrane transport, and the consequent intracellular interactions and functional cellular response represent a complex system of interwoven phenomena of transport, signaling, conformational changes, chemical activation, and/or genetic expression. The well-being of the cell thus depends on a harmonic orchestration of all these events and the existence of control mechanisms that assure the normal behavior of the various parameters involved and their orderly expression. The ability of cells to sustain life by perceiving and responding correctly to their microenvironment is the basis for development, tissue repair, and immunity, as well as normal tissue homeostasis. Natural deviations, or human-induced interference in the signaling pathways and/or inter- and intracellular transport and information transfer, are responsible for the generation, modulation, and control of diseases. The present overview aims to highlight some major topics of the highly complex cellular information transfer processes and their control mechanisms. Our goal is to contribute to the understanding of the normal and pathophysiological phenomena associated with cardiac functions so that more efficient therapeutic modalities can be developed. Our objective in this volume is to identify and enhance the study of some basic passive and active physical and chemical transport phenomena, physiological signaling pathways, and their biological consequences.

  15. Superfluous neuroscience information makes explanations of psychological phenomena more appealing.

    PubMed

    Fernandez-Duque, Diego; Evans, Jessica; Christian, Colton; Hodges, Sara D

    2015-05-01

    Does the presence of irrelevant neuroscience information make explanations of psychological phenomena more appealing? Do fMRI pictures further increase that allure? To help answer these questions, 385 college students in four experiments read brief descriptions of psychological phenomena, each one accompanied by an explanation of varying quality (good vs. circular) and followed by superfluous information of various types. Ancillary measures assessed participants' analytical thinking, beliefs on dualism and free will, and admiration for different sciences. In Experiment 1, superfluous neuroscience information increased the judged quality of the argument for both good and bad explanations, whereas accompanying fMRI pictures had no impact above and beyond the neuroscience text, suggesting a bias that is conceptual rather than pictorial. Superfluous neuroscience information was more alluring than social science information (Experiment 2) and more alluring than information from prestigious "hard sciences" (Experiments 3 and 4). Analytical thinking did not protect against the neuroscience bias, nor did a belief in dualism or free will. We conclude that the "allure of neuroscience" bias is conceptual, specific to neuroscience, and not easily accounted for by the prestige of the discipline. It may stem from the lay belief that the brain is the best explanans for mental phenomena.

  16. 8th International symposium on transport phenomena in combustion

    SciTech Connect

    1995-12-31

    The 8th International Symposium on Transport Phenomena in Combustion will be held in San Francisco, California, U.S.A., July 16-20, 1995, under the auspices of the Pacific Center of Thermal-Fluids Engineering. The purpose of the Symposium is to provide a forum for researchers and practitioners from around the world to present new developments and discuss the state of the art and future directions and priorities in the areas of transport phenomena in combustion. The Symposium is the eighth in a series; previous venues were Honolulu 1985, Tokyo 1987, Taipei 1988, Sydney 1991, Beijing 1992, Seoul 1993 and Acapulco 1994, with emphasis on various aspects of transport phenomena. The current Symposium theme is combustion. The Symposium has assembled a balanced program with topics ranging from fundamental research to contemporary applications of combustion theory. Invited keynote lecturers will provide extensive reviews of topics of great interest in combustion. Colloquia will stress recent advances and innovations in fire spread and suppression, and in low NO{sub x} burners, furnaces, boilers, internal combustion engines, and other practical combustion systems. Finally, numerous papers will contribute to the fundamental understanding of complex processes in combustion. This document contains abstracts of papers to be presented at the Symposium.

  17. Moon-based Earth Observation for Large Scale Geoscience Phenomena

    NASA Astrophysics Data System (ADS)

    Guo, Huadong; Liu, Guang; Ding, Yixing

    2016-07-01

    The capability of Earth observation for large-global-scale natural phenomena needs to be improved and new observing platform are expected. We have studied the concept of Moon as an Earth observation in these years. Comparing with manmade satellite platform, Moon-based Earth observation can obtain multi-spherical, full-band, active and passive information,which is of following advantages: large observation range, variable view angle, long-term continuous observation, extra-long life cycle, with the characteristics of longevity ,consistency, integrity, stability and uniqueness. Moon-based Earth observation is suitable for monitoring the large scale geoscience phenomena including large scale atmosphere change, large scale ocean change,large scale land surface dynamic change,solid earth dynamic change,etc. For the purpose of establishing a Moon-based Earth observation platform, we already have a plan to study the five aspects as follows: mechanism and models of moon-based observing earth sciences macroscopic phenomena; sensors' parameters optimization and methods of moon-based Earth observation; site selection and environment of moon-based Earth observation; Moon-based Earth observation platform; and Moon-based Earth observation fundamental scientific framework.

  18. Apparatus for growing crystals

    NASA Technical Reports Server (NTRS)

    Jasinski, Thomas J. (Inventor); Witt, August F. (Inventor)

    1986-01-01

    An improved apparatus and method for growing crystals from a melt employing a heat pipe, consisting of one or more sections, each section serving to control temperature and thermal gradients in the crystal as it forms inside the pipe.

  19. Crystal structure and prediction.

    PubMed

    Thakur, Tejender S; Dubey, Ritesh; Desiraju, Gautam R

    2015-04-01

    The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape.

  20. Growth of dopamine crystals

    NASA Astrophysics Data System (ADS)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  1. Crystal Structure and Prediction

    NASA Astrophysics Data System (ADS)

    Thakur, Tejender S.; Dubey, Ritesh; Desiraju, Gautam R.

    2015-04-01

    The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape.

  2. Crystallization Pathways in Biomineralization

    NASA Astrophysics Data System (ADS)

    Weiner, Steve; Addadi, Lia

    2011-08-01

    A crystallization pathway describes the movement of ions from their source to the final product. Cells are intimately involved in biological crystallization pathways. In many pathways the cells utilize a unique strategy: They temporarily concentrate ions in intracellular membrane-bound vesicles in the form of a highly disordered solid phase. This phase is then transported to the final mineralization site, where it is destabilized and crystallizes. We present four case studies, each of which demonstrates specific aspects of biological crystallization pathways: seawater uptake by foraminifera, calcite spicule formation by sea urchin larvae, goethite formation in the teeth of limpets, and guanine crystal formation in fish skin and spider cuticles. Three representative crystallization pathways are described, and aspects of the different stages of crystallization are discussed. An in-depth understanding of these complex processes can lead to new ideas for synthetic crystallization processes of interest to materials science.

  3. Charged and Neutral Particles Channeling Phenomena Channeling 2008

    NASA Astrophysics Data System (ADS)

    Dabagov, Sultan B.; Palumbo, Luigi

    2010-04-01

    On the discovery of coherent Bremsstrahlung in a single crystal at the Frascati National Laboratories / C. Barbiellini, G. P. Murtas and S. B. Dabagov -- Advances in coherent Bremsstrahlung and LPM-effect studies (to the lOOth anniversary from the birth of L. D. Landau) / N. F. Shul'ga -- Spectra of radiation and created particles at intermediate energy in oriented crystal taking into account energy loss / V. N. Baier and V. M. Katkov -- The coherent Bremsstrahlung beam at MAX-lab facility / K. Fissum ... [et al.] -- Radiation from thin, structured targets (CERN NA63) / A. Dizdar -- Hard incoherent radiation in thick crystals / N. F. Shul'ga, V. V. Syshchenko and A. I. Tarnovsky -- Coherent Bremsstrahlung in periodically deformed crystals with a complex base / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Induction of coherent x-ray Bremsstrahlung in crystals under the influence of acoustic waves / A. R. Mkrtchyan and V. V. Parazian -- Coherent processes in bent single crystals / V. A. Maisheev -- Experimental and theoretical investigation of complete transfer phenomenon for media with various heat exchange coefficients / A. R. Mkrtchyan, A. E. Movsisyan and V. R. Kocharyan -- Coherent pair production in crystals / A. R. Mkrtchyan, A. A. Saharian and V. V. Parazian -- Negative particle planar and axial channeling and channeling collimation / R. A. Carrigan, Jr. -- CERN crystal-based collimation in modern hadron colliders / W. Scandale -- Studies and application of bent crystals for beam steering at 70 GeV IHEP accelerator / A. G. Afonin ... [et al.] -- Crystal collimation studies at the Tevatron (T-980) / N. V. Mokhov ... [et al.] -- Fabrication of crystals for channeling of particles in accellerators / A. Mazzolari ... [et al.] -- New possibilities to facilitate collimation of both positively and negatively charged particle beams by crystals / V. Guidi, A. Mazzolari and V. V. Tikhomirov -- Increase of probability of particle capture into the channeling

  4. Apparatus for mounting crystal

    DOEpatents

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  5. Photonic Crystal Fibers

    DTIC Science & Technology

    2005-12-01

    passive and active versions of each fiber designed under this task. Crystal Fibre shall provide characteristics of the fiber fabricated to include core...passive version of multicore fiber iteration 2. 15. SUBJECT TERMS EOARD, Laser physics, Fibre Lasers, Photonic Crystal, Multicore, Fiber Laser 16...9 00* 0 " CRYSTAL FIBRE INT ODUCTION This report describes the photonic crystal fibers developed under agreement No FA8655-o5-a- 3046. All

  6. CRYSTAL FILTER TEST SET

    DTIC Science & Technology

    CRYSTAL FILTERS, *HIGH FREQUENCY, *RADIOFREQUENCY FILTERS, AMPLIFIERS, ELECTRIC POTENTIAL, FREQUENCY, IMPEDANCE MATCHING , INSTRUMENTATION, RADIOFREQUENCY, RADIOFREQUENCY AMPLIFIERS, TEST EQUIPMENT, TEST METHODS

  7. Crystallization from Gels

    NASA Astrophysics Data System (ADS)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  8. Hydrogen gas storage in fluorinated ultramicroporous tunnel crystal

    NASA Astrophysics Data System (ADS)

    Kataoka, Keisuke; Katagiri, Toshimasa

    2012-07-01

    We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder.We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder. Electronic supplementary information (ESI) available. CCDC 246922. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30940h

  9. Food Crystalization and Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food Crystalization and Eggs Deana R. Jones, Ph.D. USDA Agricultural Research Service Egg Safety and Quality Research Unit Athens, Georgia, USA Deana.Jones@ars.usda.gov Sugar, salt, lactose, tartaric acid and ice are examples of constituents than can crystallize in foods. Crystallization in a foo...

  10. Artistic Crystal Creations

    ERIC Educational Resources Information Center

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  11. Annealing macromolecular crystals.

    PubMed

    Hanson, B Leif; Bunick, Gerard J

    2007-01-01

    The process of crystal annealing has been used to improve the quality of diffraction from crystals that would otherwise be discarded for displaying unsatisfactory diffraction after flash cooling. Although techniques and protocols vary, macromolecular crystals are annealed by warming the flash-cooled crystal, then flash cooling it again. To apply macromolecular crystal annealing, a flash-cooled crystal displaying unacceptably high mosaicity or diffraction from ice is removed from the goniometer and immediately placed in cryoprotectant buffer. The crystal is incubated in the buffer at either room temperature or the temperature at which the crystal was grown. After about 3 min, the crystal is remounted in the loop and flash cooled. In situ annealing techniques, where the cold stream is diverted and the crystal allowed to warm on the loop prior to flash cooling, are variations of annealing that appears to work best when large solvent channels are not present in the crystal lattice or the solvent content of the crystal is relatively low.

  12. Protein Crystal Based Nanomaterials

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  13. Highly bent (110) Ge crystals for efficient steering of ultrarelativistic beams

    SciTech Connect

    De Salvador, D.; Maggioni, G.; Carturan, S.; Bazzan, M.; Argiolas, N.; Carnera, A.; Dalla Palma, M.; Della Mea, G.; Bagli, E.; Mazzolari, A.; Bandiera, L.; Guidi, V.; Lietti, D.; Berra, A.; Guffanti, G.; Prest, M.; Vallazza, E.

    2013-10-21

    Thanks to the effective electrostatic potential generated by the ordered atomic structure, bent crystals can efficiently deflect ultra relativistic charged beams by means of planar and axial channeling phenomena as well as of the recently discovered volume reflection effect. Most of the experimental knowledge about these phenomena has been gathered with Si crystals, but it has been recently demonstrated that the steering performance can be improved by using high quality Ge materials which have a larger atomic number. In this paper, we investigate channeling and volume reflection of 400 GeV protons from (110) lattice planes in highly bent Ge strips crystals. Both production and characterization of the strips are presented. Herein, the experimental results on deflection are compared with theoretical predictions, with previous published data and with the expected performances of Si crystals in similar experimental conditions.

  14. Protein crystallization with paper

    NASA Astrophysics Data System (ADS)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  15. Improving marginal crystals.

    PubMed

    Carter, Charles W; Riès-Kautt, Madeleine

    2007-01-01

    The physical chemistry of crystal growth can help to identify directions in which to look for improved crystal properties. In this chapter, we summarize how crystal growth depends on parameters that can be controlled experimentally, and relate them to the tools available for optimizing a particular crystal form for crystal shape, volume, and diffraction quality. Our purpose is to sketch the conceptual basis of optimization and to provide sample protocols derived from those foundations. We hope to assist even those who chose not to use systematic methods by enabling them to carry out rudimentary optimization searches armed with a better understanding of how the underlying physical chemistry operates.

  16. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  17. Protein Crystal Growth

    NASA Technical Reports Server (NTRS)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  18. Growth of single crystals by vapor transport in zero-gravity environment, ground-based experiments

    NASA Technical Reports Server (NTRS)

    Wiedemeier, H.

    1978-01-01

    Mass and heat transfer phenomena associated with the growth of single crystals by chemical vapor transport reactions were investigated. In this technique, a gaseous transport agent reacts with the solid source material to form exclusively gaseous products. The gas phase species migrate from the source to the condensation zone of the closed reaction ampoule where the reverse reaction occurs with formation of single crystals. The necessary concentration gradient is achieved by means of a temperature gradient.

  19. Macromolecular Crystallization in Microgravity

    NASA Technical Reports Server (NTRS)

    Snell, Edward H.; Helliwell, John R.

    2004-01-01

    The key concepts that attracted crystal growers, macromolecular or solid state, to microgravity research is that density difference fluid flows and sedimentation of the growing crystals are greatly reduced. Thus, defects and flaws in the crystals can be reduced, even eliminated, and crystal volume can be increased. Macromolecular crystallography differs from the field of crystalline semiconductors. For the latter, crystals are harnessed for their electrical behaviors. A crystal of a biological macromolecule is used instead for diffraction experiments (X-ray or neutron) to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal of a biological macromolecule then the more molecular structure detail that can be extracted. This structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences with major potential in understanding disease pathologies. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry, and mathematics meet to enable insight to the basic fundamentals of life. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment, and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyze the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural

  20. Dynamic phenomena and quality defects in laser cutting

    NASA Astrophysics Data System (ADS)

    Schuöcker, Dieter; Schuöcker, Georg

    2012-07-01

    Laser cutting of sheet metals is used all over the world by production companies since it combines high speed, excellent quality and economic advantages. Nevertheless certain limits exist for materials thickness and speed and also to quality of the cut edges that show eventually strong roughness and adherent material as dross and slag. In order to extend these limits and to approve especially cutting speed and quality of the cut edges the mechanism of laser cutting must be fully understood. As far as it concerns steady state cutting the phenomena contributed to the process with a thin liquid layer covering the momentary end of the cut kerf that serves for absorption of laser radiation and also for generation of reaction heat also for melting of the solid material and finally for the ejection of liquid material at the bottom of the work piece due to the friction with the process gas have been clarified a long time before. Also dynamic phenomena associated to reaction and to waves on the surface of the liquid body that all lead to a certain roughness have been described in the past. Nevertheless the phenomena taking place inside the liquid layer are not fully understood especially the influence of surface tension that is much higher than the pressure in the melt and would in principal inhibit any ejection of melt that is necessary for cutting. Therefore the authors carried out an analysis of the processes taking place in the liquid body that leads to a picture with a discontinuous ejection of melt and explains the formation of a rough surface structure and also of adherent material for the case of a rather thick workpiece (> 10mm).

  1. Space Commercial Opportunities for Fluid Physics and Transport Phenomena Applications

    NASA Technical Reports Server (NTRS)

    Gavert, R.

    2000-01-01

    Microgravity research at NASA has been an undertaking that has included both science and commercial approaches since the late 80s and early 90s. The Fluid Physics and Transport Phenomena community has been developed, through NASA's science grants, into a valuable base of expertise in microgravity science. This was achieved through both ground and flight scientific research. Commercial microgravity research has been primarily promoted thorough NASA sponsored Centers for Space Commercialization which develop cost sharing partnerships with industry. As an example, the Center for Advanced Microgravity Materials Processing (CAMMP)at Northeastern University has been working with cost sharing industry partners in developing Zeolites and zeo-type materials as an efficient storage medium for hydrogen fuel. Greater commercial interest is emerging. The U.S. Congress has passed the Commercial Space Act of 1998 to encourage the development of a commercial space industry in the United States. The Act has provisions for the commercialization of the International Space Station (ISS). Increased efforts have been made by NASA to enable industrial ventures on-board the ISS. A Web site has been established at http://commercial/nasa/gov which includes two important special announcements. One is an open request for entrepreneurial offers related to the commercial development and use of the ISS. The second is a price structure and schedule for U.S. resources and accommodations. The purpose of the presentation is to make the Fluid Physics and Transport Phenomena community, which understands the importance of microgravity experimentation, aware of important aspects of ISS commercial development. It is a desire that this awareness will be translated into a recognition of Fluid Physics and Transport Phenomena application opportunities coordinated through the broad contacts of this community with industry.

  2. Modeling local chemistry in the presence of collective phenomena.

    SciTech Connect

    Chandross, Michael Evan; Modine, Normand Arthur

    2005-01-01

    Confinement within the nanoscale pores of a zeolite strongly modifies the behavior of small molecules. Typical of many such interesting and important problems, realistic modeling of this phenomena requires simultaneously capturing the detailed behavior of chemical bonds and the possibility of collective dynamics occurring in a complex unit cell (672 atoms in the case of Zeolite-4A). Classical simulations alone cannot reliably model the breaking and formation of chemical bonds, while quantum methods alone are incapable of treating the extended length and time scales characteristic of complex dynamics. We have developed a robust and efficient model in which a small region treated with the Kohn-Sham density functional theory is embedded within a larger system represented with classical potentials. This model has been applied in concert with first-principles electronic structure calculations and classical molecular dynamics and Monte Carlo simulations to study the behavior of water, ammonia, the hydroxide ion, and the ammonium ion in Zeolite-4a. Understanding this behavior is important to the predictive modeling of the aging of Zeolite-based desiccants. In particular, we have studied the absorption of these molecules, interactions between water and the ammonium ion, and reactions between the hydroxide ion and the zeolite cage. We have shown that interactions with the extended Zeolite cage strongly modifies these local chemical phenomena, and thereby we have proven out hypothesis that capturing both local chemistry and collective phenomena is essential to realistic modeling of this system. Based on our results, we have been able to identify two possible mechanisms for the aging of Zeolite-based desiccants.

  3. Switching Phenomena in a System with No Switches

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  4. Physics-based prognostic modelling of filter clogging phenomena

    NASA Astrophysics Data System (ADS)

    Eker, Omer F.; Camci, Fatih; Jennions, Ian K.

    2016-06-01

    In industry, contaminant filtration is a common process to achieve a desired level of purification, since contaminants in liquids such as fuel may lead to performance drop and rapid wear propagation. Generally, clogging of filter phenomena is the primary failure mode leading to the replacement or cleansing of filter. Cascading failures and weak performance of the system are the unfortunate outcomes due to a clogged filter. Even though filtration and clogging phenomena and their effects of several observable parameters have been studied for quite some time in the literature, progression of clogging and its use for prognostics purposes have not been addressed yet. In this work, a physics based clogging progression model is presented. The proposed model that bases on a well-known pressure drop equation is able to model three phases of the clogging phenomena, last of which has not been modelled in the literature yet. In addition, the presented model is integrated with particle filters to predict the future clogging levels and to estimate the remaining useful life of fuel filters. The presented model has been implemented on the data collected from an experimental rig in the lab environment. In the rig, pressure drop across the filter, flow rate, and filter mesh images are recorded throughout the accelerated degradation experiments. The presented physics based model has been applied to the data obtained from the rig. The remaining useful lives of the filters used in the experimental rig have been reported in the paper. The results show that the presented methodology provides significantly accurate and precise prognostic results.

  5. Modelling transport phenomena in a multi-physics context

    NASA Astrophysics Data System (ADS)

    Marra, Francesco

    2015-01-01

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  6. Modelling transport phenomena in a multi-physics context

    SciTech Connect

    Marra, Francesco

    2015-01-22

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  7. Laser radiation frequency doubling in a single-crystal fibre based on a stoichiometric LiNbO{sub 3} crystal

    SciTech Connect

    Kashin, V V; Nikolaev, D A; Rusanov, S Ya; Tsvetkov, V B

    2015-01-31

    We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (λ = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO{sub 2} laser (LHPG-method). (nonlinear optical phenomena)

  8. Damping phenomena in a wire rope vibration isolation system

    NASA Technical Reports Server (NTRS)

    Tinker, M. L.; Cutchins, M. A.

    1992-01-01

    A study is presented of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, with emphasis placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase plane trajectories, and frequency response curves are obtained. A semiempirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed, and the results are compared to experimental data. Several observations and conclusions are made about the dynamic phenomena in a typical wire rope vibration isolation system based on the experimental and semiempirical results.

  9. Damping phenomena in a wire rope vibration isolation system

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L.; Cutchins, Malcolm A.

    1990-01-01

    A study of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators is presented. Emphasis is placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase trajectories, and frequency response curves were obtained. A semi-empirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed and results are compared to experimental data. Conclusions about dynamic phenomena in the wire rope system are made based on the experimental and semi-empirical results.

  10. An investigation of the damping phenomena in wire rope isolators

    NASA Technical Reports Server (NTRS)

    Cutchins, M. A.; Cochran, J. E., Jr.; Guest, S.; Fitz-Coy, N. G.; Tinker, M. L.

    1987-01-01

    Early investigations into analytically modeling the dynamics of wire rope vibration isolators are described. Results from both very simple and very complex models are shown. The dynamic model which has the best agreement to date with simple one-dimensional experiments is one which includes a Coulomb friction force which varies with frequency. There are many yet unexplained phenomena, however. The fundamentals which underly multistrand NASTRAN models are given, and some early results are shown. An application simulation is briefly described, as is ongoing research.

  11. The second part of planetary phenomena, 2000 - 2049.

    NASA Astrophysics Data System (ADS)

    He, Yunan

    1999-03-01

    This paper is the second part of planetary phenomena taking place during the period of 2000 - 2049. It gives: the times at which the outer planets reach the nodes of their orbits and the information on their reaching the greatest heliocentric latitudes, the circumstances of Venus and Mars reaching their extreme northern or southern declinations, other planets crossing the celestial equator and reaching the extreme northern or southern declinations, the circumstances of all planetary conjunctions, and the conjunctions of the planets and five bright stars (Aldebaran, Pollux, Regulux, Spica, Antares) in right ascension. The conjunctions with Pluto are not taken into consideration.

  12. Hysteresis phenomena of the intelligent driver model for traffic flow.

    PubMed

    Dahui, Wang; Ziqiang, Wei; Ying, Fan

    2007-07-01

    We present hysteresis phenomena of the intelligent driver model for traffic flow in a circular one-lane roadway. We show that the microscopic structure of traffic flow is dependent on its initial state by plotting the fraction of congested vehicles over the density, which shows a typical hysteresis loop, and by investigating the trajectories of vehicles on the velocity-over-headway plane. We find that the trajectories of vehicles on the velocity-over-headway plane, which usually show a hysteresis loop, include multiple loops. We also point out the relations between these hysteresis loops and the congested jams or high-density clusters in traffic flow.

  13. Lattice analysis for the energy scale of QCD phenomena.

    PubMed

    Yamamoto, Arata; Suganuma, Hideo

    2008-12-12

    We formulate a new framework in lattice QCD to study the relevant energy scale of QCD phenomena. By considering the Fourier transformation of link variable, we can investigate the intrinsic energy scale of a physical quantity nonperturbatively. This framework is broadly available for all lattice QCD calculations. We apply this framework for the quark-antiquark potential and meson masses in quenched lattice QCD. The gluonic energy scale relevant for the confinement is found to be less than 1 GeV in the Landau or Coulomb gauge.

  14. Measurement of Flow Phenomena in a VHTR Lower Plenum Model

    SciTech Connect

    Hugh M. McIlroy Jr.; Donald M. McEligot; Robert J. Pink

    2007-06-01

    Mean velocity and turbulence data that measure turbulent flow phenomena in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor are presented as a follow-up to summaries presented at the 2006 Annual Meeting and the 2006 Winter Meeting. The experiments were designed to develop benchmark databases to support the first Standard Problem endorsed by the Generation IV International Forum to validate the heat transfer and fluid flow software that will be used to study the behavior of the VHTR system.

  15. Optical Diagnostics of Nonequilibrium Phenomena in Highly Rarefied Gas Flows

    NASA Astrophysics Data System (ADS)

    Niimi, Tomohide

    2003-05-01

    The necessity of non-intrusive measurement of the thermodynamic variables in rarefied gas flows has motivated the development of optical diagnostics, such as electron beam fluorescence, laser induced fluorescence, coherent anti-Stokes Raman scattering, and so on. These spectroscopic methods have enabled to detect the nonequilibrium in the gas flows, based on the internal energy distributions obtained from spectral profiles. In this paper, the laser-based techniques for detection of the nonequilibrium phenomena in the highly rarefied gas flows and some results obtained by us are described.

  16. Convection phenomena at reduced gravity of importance for materials processing

    NASA Technical Reports Server (NTRS)

    Ostrach, S.

    1976-01-01

    The basic aspects of convection processes are delineated. It is shown that even in weak gravitational fields buoyancy can induce fluid motions. Furthermore, at reduced gravity other nongravity forces such as surface or interfacial tensions, g-jitter, therma-volume expansions, density differences due to phase changes, and magnetic and electric fields can induce fluid motions. The various types of flow possible with these various driving forces are described and criteria for determining the extent and nature of the resulting flows and heat transfer are presented. The various physical mechanisms that can occur separately and in combination are indicated and the present state of knowledge of each of the phenomena is outlined.

  17. Dialectic and science: Galen, Herophilus and Aristotle on phenomena.

    PubMed

    Tieleman, T

    1995-01-01

    This paper examines the nature of Galen's argument in the De placitis Hippocratis et Platonis, books 2-3, concerned with the location of the psychic functions within the body. To this question Galen applies a coherent set of methodological principles, integrating Aristotelian dialectic and scientific demonstration based on anatomical experiments. Galen disagrees with Aristotle in that he relegates the endoxa from the realm of dialectic to that of rhetoric. His attitude is marked by a distinctive emphasis on perceptible phenomena as the starting point for scientific inquiry. This and other features can be traced back to the Hellenistic scientist Herophilus.

  18. Investigation of surface tension phenomena using the KC-135 aircraft

    NASA Technical Reports Server (NTRS)

    Alter, W. S.

    1982-01-01

    The microgravity environment of the KC-135 aircraft was utilized in three experiments designed to determine the following: (1) the feasibility of measuring critical wetting temperatures; (2) the effectiveness of surface tension as a means of keeping the cushioning heat transfer liquid in the furnace during ampoule translation; and (3) whether a non-wetting fluid would separate from the ampoule wall under low gravity conditions. This trio of investigations concerning surface phenomena demonstrates the effectiveness of the KC-135 as a microgravity research environment for small-scale, hand-held experiments.

  19. Thermomagnetic phenomena in the mixed state of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Meilikhov, E. Z.

    1995-01-01

    Galvano- and thermomagnetic-phenomena in high temperature superconductors, based on kinetic coefficients, are discussed, along with a connection between the electric field and the heat flow in superconductor mixed state. The relationship that determines the transport coefficients of high temperature superconductors in the mixed state based on Seebeck and Nernst effects is developed. It is shown that this relationship is true for a whole transition region of the resistive mixed state of a superconductor. Peltier, Ettingshausen and Righi-Leduc effects associated with heat conductivity as related to high temperature superconductors are also addressed.

  20. Visualization of In-Flight Flow Phenomena Using Infrared Thermography

    NASA Technical Reports Server (NTRS)

    Banks, D. W.; vanDam, C. P.; Shiu, H. J.; Miller, G. M.

    2000-01-01

    Infrared thermography was used to obtain data on the state of the boundary layer of a natural laminar flow airfoil in supersonic flight. In addition to the laminar-to-turbulent transition boundary, the infrared camera was able to detect shock waves and present a time dependent view of the flow field. A time dependent heat transfer code was developed to predict temperature distributions on the test subject and any necessary surface treatment. A commercially available infrared camera was adapted for airborne use in this application. Readily available infrared technology has the capability to provide detailed visualization of various flow phenomena in subsonic to hypersonic flight regimes.