Sample records for core confinement regimes

  1. Ohmic energy confinement saturation and core toroidal rotation reversal in Alcator C-Mod plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rice, J. E.; Greenwald, M. J.; Podpaly, Y. A.; Reinke, M. L.; Hughes, J. W.; Howard, N. T.; Ma, Y.; Cziegler, I.; Ennever, P. C.; Ernst, D.; Fiore, C. L.; Gao, C.; Irby, J. H.; Marmar, E. S.; Porkolab, M.; Tsujii, N.; Wolfe, S. M. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Diamond, P. H. [UCSD, La Jolla, California 92903 (United States); Duval, B. P. [CRPP, EPFL, Lausanne 1015 (Switzerland)


    Ohmic energy confinement saturation is found to be closely related to core toroidal rotation reversals in Alcator C-Mod tokamak plasmas. Rotation reversals occur at a critical density, depending on the plasma current and toroidal magnetic field, which coincides with the density separating the linear Ohmic confinement regime from the saturated Ohmic confinement regime. The rotation is directed co-current at low density and abruptly changes direction to counter-current when the energy confinement saturates as the density is increased. Since there is a bifurcation in the direction of the rotation at this critical density, toroidal rotation reversal is a very sensitive indicator in the determination of the regime change. The reversal and confinement saturation results can be unified, since these processes occur in a particular range of the collisionality.

  2. Impurity confinement and transport in high confinement regimes without edge localized modes on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Grierson, B. A., E-mail:; Nazikian, R. M.; Solomon, W. M. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Burrell, K. H.; Garofalo, A. M.; Belli, E. A.; Staebler, G. M.; Evans, T. E.; Smith, S. P.; Chrobak, C. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Fenstermacher, M. E. [Lawerence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); McKee, G. R. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53796 (United States); Orlov, D. M. [Center for Energy Research, University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Chrystal, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)


    Impurity transport in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated in stationary high confinement (H-mode) regimes without edge localized modes (ELMs). In plasmas maintained by resonant magnetic perturbation (RMP), ELM-suppression, and QH-mode, the confinement time of fluorine (Z = 9) is equivalent to that in ELMing discharges with 40 Hz ELMs. For selected discharges with impurity injection, the impurity particle confinement time compared to the energy confinement time is in the range of τ{sub p}/τ{sub e}≈2−3. In QH-mode operation, the impurity confinement time is shown to be smaller for intense, coherent magnetic, and density fluctuations of the edge harmonic oscillation than weaker fluctuations. Transport coefficients are derived from the time evolution of the impurity density profile and compared to neoclassical and turbulent transport models NEO and TGLF. Neoclassical transport of fluorine is found to be small compared to the experimental values. In the ELMing and RMP ELM-suppressed plasma, the impurity transport is affected by the presence of tearing modes. For radii larger than the mode radius, the TGLF diffusion coefficient is smaller than the experimental value by a factor of 2–3, while the convective velocity is within error estimates. Low levels of diffusion are observed for radii smaller than the tearing mode radius. In the QH-mode plasma investigated, the TGLF diffusion coefficient is higher inside of ρ=0.4 and lower outside of 0.4 than the experiment, and the TGLF convective velocity is more negative by a factor of approximately 1.7.

  3. Free Energy of a Polymer in Slit-Like Confinement across the Odijk, moderate confinement, and Bulk Regimes (United States)

    Kamanzi, Albert; Leith, Jason S.; Sean, David; Berard, Daniel; Guthrie, Andrew C.; McFaul, Christopher M. J.; Slater, Gary W.; de Haan, Hendrick W.; Leslie, Sabrina R.; McGill University Team; University of Ottawa, University of Ontario Collaboration

    We directly measure the free energy of confinement for semi-flexible polymers from the nanoscale to bulk regimes in slit-like confinement. We use Convex Lens-induced Confinement (CLiC) microscopy of DNA to load and directly count molecules at equilibrium in a single chamber of smoothly increasing height. CLiC microscopy allows for direct visualization of polymers in free solution over long periods, as a function of tunable vertical confinement - from the millimeter to the nanometer scale, and within a single device. Our direct characterization of the free energy of confinement, across several orders of magnitude of applied confinement, agree with new simulations established in this work. We compare experimental results to the ``de Gennes blob model'', to theory published by Casassa, as well as to simulations by Chen and Sullivan, in appropriate regimes. This work establishes a robust platform for understanding and manipulating polymers at the nanoscale, with a wide range of applications to biomedical technologies.

  4. Confinement less spectral behavior in hollow-core Bragg fibers

    DEFF Research Database (Denmark)

    Foroni, M.; Passaro, D.; Poli, F.


    The influence of each cross-section geometric parameter on hollow-core Bragg fiber guiding properties has been numerically investigated. Fabricated fibers have been modeled, giving insight into the spectral behavior of the confinement loss. It has been verified that, by changing the amount...... of silica and air in the fiber cladding, it is possible to change the reflection conditions undergone by the field within the core, thus shifting the confinement loss spectrum....

  5. Mars: a new core-crystallization regime

    NARCIS (Netherlands)

    Stewart, A.J.; Schmidt, M.W.; van Westrenen, W.; Liebske, C.


    The evolution of the martian core is widely assumed to mirror the characteristics observed for Earth's core. Data from experiments performed on iron-sulfur and iron-nickel-sulfur systems at pressures corresponding to the center of Mars indicate that its core is presently completely liquid and that

  6. Probing quantum confinement within single core-multishell nanowires


    Martínez-Criado, Gema; Homs, Alejandro; Alén, Benito; Sans, Juan Ángel; Segura-Ruiz, Jaime; Molina-Sánchez, Alejandro; Susini, Jean; Yoo, Jinkyoung; Yi, J. G. C.


    Theoretically core-multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier localization phenomena at the hexagon corners by combining synchrotron excited optical luminescence with simultaneous X-ray fluorescence spectroscopy. Applied to single coaxial n-GaN/InGaN multiquantum-well/p-GaN nanowires, our experiment narrows the gap between optical microscopy and high-r...

  7. Controlling the Cross-phase: A mechanism for the I-mode and other enhanced confinement regimes? (United States)

    Newman, D. E.; Terry, P. W.; Sanchez, R.


    The I-mode and similar new transport regimes offer good confinement properties with reduced density limit issues and better control. While a number of different mechanisms have been identified for the formation and maintenance of enhanced confinement regimes few if any allow enhanced confinement in one channel but not another which is seen in the I-mode. We propose differential cross-phase modification as a possible mechanism for different transport in different channels. Simple dynamical models have been able to capture a remarkable amount of the dynamics of the core and edge transport barriers found in many devices. By including in this rich though simple dynamic transport model a simple model for cross phase effects, due to multiple instabilities, between the transported fields such as density and temperature, we can investigate whether the dynamics of more continuous transitions such as the I-mode can be captured and understood. This is backed up by multi-scale simulations on full gyro-kinetic codes. If correct this could have broad implications for transport in many systems. If this mechanism is valid, what can the model tell us about control knobs for these promising regimes?.

  8. Spindle-cusp confinement properties of laser-produced plasma in a low-beta regime

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, R.; Sekiguchi, T. (Tokyo Univ. (Japan). Faculty of Engineering); Sato, K.


    Behavior of a spindle-cusp plasma produced at its central null-field point from a thin wire target by laser pulse is experimentally studied, mainly in a low plasma-beta regime, by means of many different plasma diagnostics. As the results, somewhat queer confinement properties have been found, and some considerations are given for the observed results.

  9. Scaling regimes of thermocapillarity-driven dynamics of confined long bubbles: Effects of disjoining pressure (United States)

    Chaudhury, Kaustav; Chakraborty, Suman


    During thermocapillary transport of a confined long bubble, we unveil the existence of a contrary-to-the-conventional disjoining-pressure-dominant scaling regime characterizing the dynamics of the thin liquid film engulfed between the bubble interface and the channel surface. Such a regime is realized for the limitingly small magnitude of the Marangoni stress (surface tension gradient) when the separating liquid region reaches an ultrathin dimension. Over this regime, we witness a severe breakdown of the seemingly intuitive scaling arguments based on the balance of viscous and capillary forces. Starting from competent balance criteria, we uncover the characteristic length scales involved, leading towards obtaining the new consistent scaling laws of the disjoining-pressure-dominant regime, in a simple closed form analytical fashion. Our scaling estimations are substantiated by full-scale numerical simulations of the pertinent thin-film equations. These new scaling laws appear to be convenient for implementing as a fundamental design basis for multiphase microfluidic systems.

  10. Transport and turbulence studies in the linear ohmic confinement regime in Alcator C-Mod (United States)

    Porkolab, M.; Dorris, J.; Ennever, P.; Fiore, C.; Greenwald, M.; Hubbard, A.; Ma, Y.; Marmar, E.; Podpaly, Y.; Reinke, M. L.; Rice, J. E.; Rost, J. C.; Tsujii, N.; Ernst, D.; Candy, J.; Staebler, G. M.; Waltz, R. E.


    Transport in ohmically heated plasmas in Alcator C-Mod was studied in both the linear (LOC) and saturated (SOC) ohmic L-mode confinement regimes and the importance of turbulent transport in the region r/a = 0.5-0.8 was established. After an extensive analysis with TGLF and GYRO, it is found that using an effective impurity ion species with Zi = 8, and moderately high Zeff (2.0-5.6), in the LOC regime electron transport becomes dominant due to TEM turbulence. The key ingredient in the present results is the observation that dilution of the main ion species (deuterium) by impurity species of moderate charge state reduces dominant ITG turbulence, in contrast to the SOC regime with little, if any dilution. The turbulent spectrum measured with the phase contrast imaging (PCI) diagnostic is in qualitative agreement with predictions of a synthetic PCI diagnostic adopted to Global GYRO. The toroidal rotation in the low-density LOC regime is in the co-current direction but as the density is raised in the SOC regime the rotation reverses to the counter current drive direction. The impurity content of the plasma was measured recently and an effective Zi of 9 was deduced.

  11. Changes in core electron temperature fluctuations across the ohmic energy confinement transition in Alcator C-Mod plasmas (United States)

    Sung, C.; White, A. E.; Howard, N. T.; Oi, C. Y.; Rice, J. E.; Gao, C.; Ennever, P.; Porkolab, M.; Parra, F.; Mikkelsen, D.; Ernst, D.; Walk, J.; Hughes, J. W.; Irby, J.; Kasten, C.; Hubbard, A. E.; Greenwald, M. J.; the Alcator C-Mod Team


    The first measurements of long wavelength (kyρs < 0.3) electron temperature fluctuations in Alcator C-Mod made with a new correlation electron cyclotron emission diagnostic support a long-standing hypothesis regarding the confinement transition from linear ohmic confinement (LOC) to saturated ohmic confinement (SOC). Electron temperature fluctuations decrease significantly (∼40%) crossing from LOC to SOC, consistent with a change from trapped electron mode (TEM) turbulence domination to ion temperature gradient (ITG) turbulence as the density is increased. Linear stability analysis performed with the GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) shows that TEMs are dominant for long wavelength turbulence in the LOC regime and ITG modes are dominant in the SOC regime at the radial location (ρ ∼ 0.8) where the changes in electron temperature fluctuations are measured. In contrast, deeper in the core (ρ < 0.8), linear stability analysis indicates that ITG modes remain dominant across the LOC/SOC transition. This radial variation suggests that the robust global changes in confinement of energy and momentum occurring across the LOC/SOC transition are correlated to local changes in the dominant turbulent mode near the edge.

  12. Heating, current drive and confinement regimes with the JET ICRH and LHCD systems

    DEFF Research Database (Denmark)

    Jacquinot, J.; Adams, J.M.; Altmann, H.


    by pellet injection. A value of n(d) tau-E T(i) = 7.8 x 10(20) m-3 s keV was obtained in this mode with T(e) approximately T(i) approximately 11 keV. In the L-mode regime, a regime, a record (140 kW) D-He-3 fusion power was generated with 10 - 14 MW of ICRH at the He-3 cyclotron frequency. Experiments were......-mode conditions. A maximum power of 22 MW was coupled to L-mode plasmas. High quality H-modes (tau-E greater-than-or-equal-to 2.5 tau-EG) were achieved using dipole phasing. A new high confinement mode was discovered. It combines the properties of the H-mode regime to the low central diffusivities obtained...... performed with the prototype launcher of the Lower Hybrid Current Drive (LHCD) systems with coupled power up to 1.6 MW with current drive efficiencies up to R I(CD)/P = 0.4 x 10(20) m-2 A/W. Fast electrons are driven by LHCD to tail temperatures of 100 keV with a hollow radial profile...

  13. Optical and Structural Characterization of Confined and Strained Core/Multi-Shell Semiconducting Nanowires (United States)

    Fickenscher, Melodie

    -hole lifetimes to fall below the system response (correlate dislocation density with the PL intensity, bandgap position, and TO2 phonon. High resolution imaging shows that dislocations are both full and frank partial dislocations in the (111) axial plane which relieve the axial strain. Radial strain relief can be seen in the cross slip of dislocations to the other (111) planes. Finally, we see evidence for growth of coherently strained NW structures without dislocations at core/shell thickness regimes predicted by theoretical predictions of their formation energies. We conclude this work by minimizing the effect of dislocations on the core by first growing a thin AlGaAs shell to protect the core from the dislocation recombination centers, and find that the 150nm core produces optimal results. Finally, we demonstrate control of radial confinement through the growth of 7nm and 4nm GaAs radial quantum wells embedded within concentric AlGaAs barriers. PL shows confined QW emission shifted by 55meV and 185meV from the free exciton peak (1.515eV). TRPL shows good material quality with lifetimes in excess of 300ps for core and QW states. Structural HRSTEM data showing tapering of the QW matches the extracted temporal and spatial scans from TRPL which show movement of excitons from smaller wells at higher energies to wider sections at lower energies of the QW. We find that the PL is consistent with modeling results for a 6nm--7nm QW with 24% AlGaAs.

  14. Geochemical changes and fracture development in Woodford Shale cores following hydrous pyrolysis under uniaxial confinement (United States)

    Birdwell, Justin E.; Lewan, Michael D.; Miller, Michael; Baez, Luis; Beeney, Ken; Sonnenberg, Steve


    A uniaxial confinement clamp was used on Woodford Shale cores in hydrous pyrolysis experiments to study fracture development during thermal maturation. The clamp simulates overburden in that it prevents cores from expanding perpendicular to bedding fabric during the volume-increasing reactions associated with petroleum generation. Cores were cut from a slab of immature Woodford Shale and subjected to hydrous pyrolysis under confinement at 300, 330, and 365 °C for 72 hours to induce thermal maturities ranging from early bitumen to maximum expelled-oil generation. Two additional cores were used as experimental controls: (1) a confined core was saturated with water by heating it to 100 °C under hydrous pyrolysis conditions for 72 hours to use for characterization of the original rock, and (2) an unconfined core was heated at 365 °C for 72 hours to evaluate the effects of confinement on petroleum generation and expulsion. X-ray computed tomography (X-CT) imaging and other analyses identified five distinct beds within the cored interval. Using a tentative classification system, beds 1, 2, and 3 are described as dolomitic marlstone (DM) with total organic carbon (TOC) contents of 7.7, 5.8, and 7.7 wt. %, respectively; bed 4 is a cherty quartzose claystone (CQC) with TOC content of 5.5 wt. %; and bed 5 is a quartzose claystone with TOC content of 10.9 wt. %. Bed samples all had similar Rock-Eval hydrogen indices (600 ± 46 mg S2/g-TOC) and Tmax values (433 ± 2 °C), demonstrating organic matter uniformity and low thermal maturity. The X-CT scan of the core heated to 100 °C showed preexisting fractures that were nearly perpendicular to the bedding fabric primarily in the low-TOC DM bed 2 and CQC bed 4. Heating led to enhancement of preexisting fractures in the confined cores with the greatest enhancement occurring in CQC bed 4. The fractures increased in size and intensity with temperature. This is attributed to the internal pressure generated by volume

  15. Thermal transport in Si and Ge nanostructures in the `confinement' regime (United States)

    Kwon, Soonshin; Wingert, Matthew C.; Zheng, Jianlin; Xiang, Jie; Chen, Renkun


    Reducing semiconductor materials to sizes comparable to the characteristic lengths of phonons, such as the mean-free-path (MFP) and wavelength, has unveiled new physical phenomena and engineering capabilities for thermal energy management and conversion systems. These developments have been enabled by the increasing sophistication of chemical synthesis, microfabrication, and atomistic simulation techniques to understand the underlying mechanisms of phonon transport. Modifying thermal properties by scaling physical size is particularly effective for materials which have large phonon MFPs, such as crystalline Si and Ge. Through nanostructuring, materials that are traditionally good thermal conductors can become good candidates for applications requiring thermal insulation such as thermoelectrics. Precise understanding of nanoscale thermal transport in Si and Ge, the leading materials of the modern semiconductor industry, is increasingly important due to more stringent thermal conditions imposed by ever-increasing complexity and miniaturization of devices. Therefore this Minireview focuses on the recent theoretical and experimental developments related to reduced length effects on thermal transport of Si and Ge with varying size from hundreds to sub-10 nm ranges. Three thermal transport regimes - bulk-like, Casimir, and confinement - are emphasized to describe different governing mechanisms at corresponding length scales.

  16. Extremely High-Birefringent Asymmetric Slotted-Core Photonic Crystal Fiber in THz Regime

    DEFF Research Database (Denmark)

    Islam, Raonaqul; Habib, Selim; Hasanuzzaman, G.K.M.


    of the circular cladding confines most of the power in the fiber-core. The fiber structure reported in this letter exhibits simultaneously ultrahigh modal birefringence of 7.5 × 10−2 and a very low effective absorption loss of 0.07 cm−1 for y-polarization mode at an operating frequency of 1 THz. It is highly...

  17. Marek's disease in local chicken strains of Ethiopia reared under confined management regime in central Ethiopia

    NARCIS (Netherlands)

    Duguma, R.; Yami, A.; Dana, N.; Hassen, H.H.; Esatu, W.


    The prevalence, clinical and pathological manifestations and extent of mortality due to Marek’s disease (MD) was investigated from November 2003 to January 2004 among indigenous chickens of Ethiopia reared under confined management at the Debre Zeit Agricultural Research Center, central Ethiopia.

  18. A Statistical Analysis of the Scaling Laws for the Confinement Time Distinguishing between Core and Edge (United States)

    Peluso, E.; Gelfusa, M.; Murari, A.; Lupelli, I.; Gaudio, P.

    The H mode of confinement in Tokamaks is characterized by a thin region of high gradients, located at the edge of the plasma and called the Edge Transport Barrier. Even if various theoretical models have been proposed for the interpretation of the edge physics, the main empirical scaling laws of the plasma confinement time are expressed in terms of global plasma parameters and they do not discriminate between the edge and core regions. Moreover all the scaling laws are assumed to be power law monomials. In the present paper, a new methodology is proposed to investigate the validity of both assumptions. The approach is based on Symbolic Regression via Genetic Programming and allows first the extraction of the most statistically reliable models from the available experimental data in the ITPA database. Non linear fitting is then applied to the mathematical expressions found by Symbolic regression. The obtained scaling laws are compared with the traditional scalings in power law form.

  19. The influence of divertor geometry on access to high confinement regimes on the Alcator C-Mod tokamak (United States)

    Hughes, J. W.; Labombard, B.; Hubbard, A.; Marmar, E.; Terry, J.; Rice, J.; Walk, J.; Whyte, D.; Ma, Y.; Cziegler, I.; Edlund, E.; Theiler, C.


    The placement of X-point and strike points in a diverted tokamak can have a remarkable impact on properties of the discharge, including thermal and particle confinement. The distinctive divertor of Alcator C-Mod allows us to demonstrate these effects experimentally, as we vary equilibrium shaping to obtain substantial variation of divertor leg length, field line attack angle and divertor baffling. In response to these changes, we observe differences in both L-mode confinement and access to high-confinement regimes (i.e. ELMy H-mode and I-mode). With the ion grad-B drift directed toward the divertor, scanning the strike point can induce ~2× reductions in H-mode power threshold, and can produce a window for I-mode operation with H98 > 1. Recent experiments seek to explore these effects using improved diagnostics, and to extend them to the case with ion grad-B drift directed away from the divertor. Supported by USDoE award DE-FC02-99ER54512.

  20. Optical rectification in quantum wells within different confinement and nonlinearity regimes (United States)

    Solaimani, M.; Ali Aleomraninejad, Seyed Mohammad; Lavaei, Leila


    In this paper, we study the effect of conduction band non-parabolicity on optical rectification coefficients (ORCs) of quantum well systems by using compact density matrix approach. To investigate the non-parabolicity effect, we include a fourth derivative of the wave function in the Schrödinger equation. Our calculations are based on high accuracy 3, 5, 13 and 15 points finite difference methods that are developed by an interpolation approach. We show that, in some situations, the conduction band non-parabolicity can considerably affect the optical properties. Thus, it is necessary to include the conduction band non-parabolicity effects. We compare three different structures GaAs/AlxGa1-xAs (weak confinement & medium nonlinearity), GaN/AlN (strong confinement & weak nonlinearity) and InSb/GaSb (medium confinement & strong nonlinearity). We show that the non-parabolicity is very important for systems with smaller system lengths. For fixed geometrical parameters, the ORC of Al0.3Ga0.7As/GaAS quantum wells is greater than that of GaN/AlN quantum wells and the ORC of GaN/AlN quantum wells is greater than that of InSb/GaSb quantum wells. The behavior of the ORC under the influence of the applied electric field is different for the three above-mentioned quantum well systems. The red or blue shift of the ORC peak positions is more observable for systems with larger Leff.

  1. An MR/MRI compatible core holder with the RF probe immersed in the confining fluid (United States)

    Shakerian, M.; Balcom, B. J.


    An open frame RF probe for high pressure and high temperature MR/MRI measurements was designed, fabricated, and tested. The open frame RF probe was installed inside an MR/MRI compatible metallic core holder, withstanding a maximum pressure and temperature of 5000 psi and 80 °C. The open frame RF probe was tunable for both 1H and 19F resonance frequencies with a 0.2 T static magnetic field. The open frame structure was based on simple pillars of PEEK polymer upon which the RF probe was wound. The RF probe was immersed in the high pressure confining fluid during operation. The open frame structure simplified fabrication of the RF probe and significantly reduced the amount of polymeric materials in the core holder. This minimized the MR background signal detected. Phase encoding MRI methods were employed to map the spin density of a sulfur hexafluoride gas saturating a Berea core plug in the core holder. The SF6 was imaged as a high pressure gas and as a supercritical fluid.

  2. An MR/MRI compatible core holder with the RF probe immersed in the confining fluid. (United States)

    Shakerian, M; Balcom, B J


    An open frame RF probe for high pressure and high temperature MR/MRI measurements was designed, fabricated, and tested. The open frame RF probe was installed inside an MR/MRI compatible metallic core holder, withstanding a maximum pressure and temperature of 5000 psi and 80 °C. The open frame RF probe was tunable for both 1H and 19F resonance frequencies with a 0.2 T static magnetic field. The open frame structure was based on simple pillars of PEEK polymer upon which the RF probe was wound. The RF probe was immersed in the high pressure confining fluid during operation. The open frame structure simplified fabrication of the RF probe and significantly reduced the amount of polymeric materials in the core holder. This minimized the MR background signal detected. Phase encoding MRI methods were employed to map the spin density of a sulfur hexafluoride gas saturating a Berea core plug in the core holder. The SF6 was imaged as a high pressure gas and as a supercritical fluid. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The regime of the improved confinement with deuterium pellet injected into plasmas of tokamak T-10 with W and Li limiters (United States)

    Ryzhakov, D. V.; Pavlov, Yu D.; Borschegovskiy, A. A.; Gorshkov, A. V.; Kapralov, V. G.; Klyuchnikov, L. A.; Krylov, S. V.; Malzev, S. G.; Sergeev, D. S.


    In this paper, we present the first, after replacing a graphite limiter with a tungsten limiter, experimental results of the regimes of improved plasma confinement in the T-10 tokamak when injecting deuterium pellets. Comparison with the results of previous experiments with a graphite limiter shows the preservation of the improved confinement effect. Preliminary results of the experiments on the change in poloidal angle of injection of pellets allow us to say that with the central injection, the maximum effect of improved confinement is observed.

  4. Analysis of Fracture in Cores from the Tuff Confining Unit beneath Yucca Flat, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Lance Prothro


    The role fractures play in the movement of groundwater through zeolitic tuffs that form the tuff confining unit (TCU) beneath Yucca Flat, Nevada Test Site, is poorly known. This is an important uncertainty, because beneath most of Yucca Flat the TCU lies between the sources of radionuclide contaminants produced by historic underground nuclear testing and the regional carbonate aquifer. To gain a better understanding of the role fractures play in the movement of groundwater and radionuclides through the TCU beneath Yucca Flat, a fracture analysis focusing on hydraulic properties was performed on conventional cores from four vertical exploratory holes in Area 7 of Yucca Flat that fully penetrate the TCU. The results of this study indicate that the TCU is poorly fractured. Fracture density for all fractures is 0.27 fractures per vertical meter of core. For open fractures, or those observed to have some aperture, the density is only 0.06 fractures per vertical meter of core. Open fractures are characterized by apertures ranging from 0.1 to 10 millimeter, and averaging 1.1 millimeter. Aperture typically occurs as small isolated openings along the fracture, accounting for only 10 percent of the fracture volume, the rest being completely healed by secondary minerals. Zeolite is the most common secondary mineral occurring in 48 percent of the fractures observed.

  5. Ablative stabilization of the Rayleigh-Taylor instability in regimes relevant to inertial confinement fusion

    Energy Technology Data Exchange (ETDEWEB)

    Kilkenny, J.D.


    As shown elsewhere an ablatively imploded shell is hydrodynamically unstable, the dominant instability being the well known Rayleigh-Taylor instability with growth rate {gamma} = {radical}Akg where k = 2{pi}/{lambda} is the wave number, g is the acceleration and A the Attwood number ({rho}{sub hi} {minus} {rho}{sub lo})/({rho}{sub hi} + {rho}{sub lo}) where {rho}{sub hi} is the density of the heavier fluid and {rho}{sub lo} is the density of the lighter fluid. A theoretical understanding of ablative stabilization has gradually evolved, confirmed over the last five years by experiments. The linear growth is very well understood with excellent agreement between experiment and simulation for planar geometry with wavelengths in the region of 30--100{mu}m. There is an accurate, albeit phenomenological dispersion relation. The non-linear growth has been measured and agrees with calculations. In this lecture, the authors go into the fundamentals of the Rayleigh-Taylor instability and the experimental measurements that show it is stabilized sufficiently by ablation in regimes relevant to ICF.

  6. SXR-XUV Diagnostics for Edge and Core of Magnetically Confined Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stutman, Dan [Johns Hopkins University


    The present report summarizes the results obtained during a one-year extension of DoE grant “SXR-XUV Diagnostics for Edge and Core of Magnetically Confined Plasmas”, at Johns Hopkins University, aimed at completing the development of a new type of magnetic fusion plasma diagnostic, the XUV Transmission Grating Imaging Radiometer (TGIR). The TGIR enables simultaneous spatially and spectrally resolved measurements of the XUV/VUV radiated power from impurities in fusion plasmas, with high speed. The instrument was successfully developed and qualified in the laboratory and in experiments on a tokamak. Its future applications will be diagnostic of the impurity content and transport in the divertor and edge of advanced magnetic fusion experiments, such as NSTX Upgrade.

  7. Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement (United States)

    Rajadell, Fernando; Climente, Juan I.; Planelles, Josep


    Using semianalytical models we calculate the energy, effective Bohr radius, and radiative lifetime of neutral excitons confined in CdSe colloidal nanoplatelets (NPLs). The excitonic properties are largely governed by the electron-hole in-plane correlation, which in NPLs is enhanced by the quasi-two-dimensional motion and the dielectric mismatch with the organic environment. In NPLs with lateral size L ≳20 nm the exciton behavior is essentially that in a quantum well, with super-radiance leading to exciton lifetimes of 1 ps or less, only limited by the NPL area. However, for L crown configurations. In the former, the strong vertical confinement limits separation of electrons and holes even for type-II band alignment. The exciton behavior is then similar to that in core-only NPL, albeit with weakened dielectric effects. In the latter, charge separation is also inefficient if band alignment is quasi-type-II (e.g., in CdSe/CdS), because electron-hole interaction drives both carriers into the core. However, it becomes very efficient for type-II alignment, for which we predict exciton lifetimes reaching microseconds.

  8. Toroidal Rotation and Core Ion Confinement with RF Heating in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    deGrassie, J.S.; Greenfield, C.M.; Baker, D.R.; Burrell, K.H.; Lin-Liu, Y.R.; Lohr, J.; Luce, T.C.; Petty, C.C.; Prater, R.; Staebler, G.M.; Heidbrink, W.W.; Rice, B.W. Rice, Mau, T.K.; Porkolab, M.


    Shear in the E x B flow velocity can stabilize turbulent transport [1], and so it is of interest to understand the physics behind electric field generation and modification in the tokamak. In DIII-D the core radial electric field in many regimes is generated by flow velocities driven by momentum input from neutral beam injection (NBI). In a variety of conditions it is observed that direct electron heating is accompanied by a reduction in the NBI driven toroidal rotation velocity, U{sub {phi}}, and the ion temperature, T{sub i}, primarily in the core, {rho} <0.5 (where {rho} is a radial coordinate of the normalized toroidal flux). This electron heating can be done with either electron cyclotron heating (ECH) or fast wave electron heating (FWEH). Both can be accompanied by the reduction in U{sub {phi}} and T{sub i} [2-4]. Details of the parallel wavenumber (k//) spectrum of the launched rf do not seem to be important in either case for the effect to exist. Reductions are observed for EC waves launched with nonzero k// for current drive or launched radially with k//=0; and for FWEH with waves directed either co or counter, using the DIII-D four strap antennas [5], This universality indicates that increased electron temperature, T{sub e}, is increasing ion momentum and thermal transport, at least in the parameter regimes of these experiments. It is also possible that nonambipolar transport of resonantly heated particles is playing a role. To date, the great majority of the DIII-D experiments have been conducted with the rf target discharges driven by co-injected NBI.

  9. Calculation and analysis of generator limiting regimes with respect to stator end core heating

    Directory of Open Access Journals (Sweden)

    Kostić Miloje


    Full Text Available A new simplified procedure for defining the limiting operating regimes on the generator capability curve, with respect to stator end core heating, is proposed and described in this paper. First of all, a simplified analysis of axial flux leakage that penetrates into the end plates of the stator is carried out and the corresponding power losses are calculated. Then the analysis of measured point temperature increases over the stator end core, and a qualitative and quantitative overview of the effects, are presented. A simplified procedure for defining the limiting regime with regard to the heating stator end core, which is illustrated for the case of an operating diagram for a given generator of apparent power of 727 MVA (B2 is also described. The given limiting line constructed using this method is similar to the appropriate line constructed on the basis of complex and lengthy factory and on-site tests performed by the manufacturer and the user. According to the results and the check, the proposed method has been proved and the application of the simplified procedure can be recommended for use along with other procedures, at least when it comes to similar synchronous generators in Serbia's Electric Power Industry.

  10. Thermonuclear reactions probed at stellar-core conditions with laser-based inertial-confinement fusion (United States)

    Casey, D. T.; Sayre, D. B.; Brune, C. R.; Smalyuk, V. A.; Weber, C. R.; Tipton, R. E.; Pino, J. E.; Grim, G. P.; Remington, B. A.; Dearborn, D.; Benedetti, L. R.; Frenje, J. A.; Gatu-Johnson, M.; Hatarik, R.; Izumi, N.; McNaney, J. M.; Ma, T.; Kyrala, G. A.; MacLaren, S.; Salmonson, J.; Khan, S. F.; Pak, A.; Hopkins, L. Berzak; Lepape, S.; Spears, B. K.; Meezan, N. B.; Divol, L.; Yeamans, C. B.; Caggiano, J. A.; McNabb, D. P.; Holunga, D. M.; Chiarappa-Zucca, M.; Kohut, T. R.; Parham, T. G.


    Stars are giant thermonuclear plasma furnaces that slowly fuse the lighter elements in the universe into heavier elements, releasing energy, and generating the pressure required to prevent collapse. To understand stars, we must rely on nuclear reaction rate data obtained, up to now, under conditions very different from those of stellar cores. Here we show thermonuclear measurements of the 2H(d, n)3He and 3H(t,2n)4He S-factors at a range of densities (1.2-16 g cm-3) and temperatures (2.1-5.4 keV) that allow us to test the conditions of the hydrogen-burning phase of main-sequence stars. The relevant conditions are created using inertial-confinement fusion implosions at the National Ignition Facility. Our data agree within uncertainty with previous accelerator-based measurements and establish this approach for future experiments to measure other reactions and to test plasma-nuclear effects present in stellar interiors, such as plasma electron screening, directly in the environments where they occur.

  11. Evidence of long-distance correlation of fluctuations during edge transitions to improved-confinement regimes in the TJ-II stellarator. (United States)

    Pedrosa, M A; Silva, C; Hidalgo, C; Carreras, B A; Orozco, R O; Carralero, D


    Long-distance coupling between edge parameters' fluctuations has been investigated in the TJ-II stellarator. Results show long-range correlations in potential fluctuations, which are amplified by the development of radial electric fields during transitions to improved-confinement regimes, whereas there is no correlation between ion saturation current signals. These experimental findings suggest the importance of long-range correlations as a new fingerprint of the plasma behavior during the development of edge shear flows and the key role of electric fields to amplify them.

  12. Observation of Distinct Two-Photon Transition Channels in CdTe Quantum Dots in a Regime of Very Strong Confinement

    Directory of Open Access Journals (Sweden)

    Marcelo Gonçalves Vivas


    Full Text Available We report here on the direct observation of distinct two-photon transition channels in glutathione-capped (GSH CdTe quantum dots (QDs in a very strong confinement regime. CdTe-GSH QDs with different average diameters (2.5, 3.0, and 3.3 nm were synthesized through the one-pot method and their two-photon absorption (2PA spectrum determined by a femtosecond wavelength-tunable Z-scan. Our results show that the two lower-energy one-photon-allowed excitonic transitions, 1S3/2(h → 1S(e and 2S3/2(h → 1S(e, are also accessed via 2PA. These results were ascribed to the relaxation of the parity selection rules due to the noncentrosymmetric structure of the CdTe QDs (zinc-blended structure, whose magnitude are determined by surface defects and structural irregularities present in CdTe-GSH QDs, in the strong confinement regime.

  13. Comparison of non-neutral electron plasma confinement in harmonic and rectangular potentials in a very dense regime

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, T. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Physics department, Faculty of Science, Beni-Suef University (Egypt); Mohri, A. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yamazaki, Y. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute of Physics, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902 (Japan)


    Confinement of high density electron plasmas in a strong uniform magnetic field was experimentally studied in a multi-ring trap (MRT). The trap was housed inside a bore tube and surrounded by a superconducting solenoid. A 5 T magnetic field was used to provide radial confinement while an electrostatic harmonic or rectangular potential well was used for axial confinement. For trapped electrons of N = 1.2 Multiplication-Sign 10{sup 10} in a harmonic potential well (HPW) with the trap length of L{sub T} = 320 mm, the plasma lifetime was about 10{sup 4} s and it became much longer at lower N = 4.5 Multiplication-Sign 10{sup 9}. Such long holding times were achieved without application of rotating electric fields. Contrastingly, in a rectangular potential well (RPW), the plasma of N = 1.2 Multiplication-Sign 10{sup 10} under the same trap length expanded to cover the whole Faraday Cup within 200 s, where its radial expansion rate was {eta} = 3.2 Multiplication-Sign 10{sup -2} mm/s, which was 20 times faster than HPW. The lifetime for RPW became shorter with increasing L{sub T} and scaled as 1/[L{sub T}]{sup 2}. This scaling found for high density plasmas is similar to the obtained one with different Penning-Malmberg traps at UC San Diego (USCD).

  14. Ground state properties and non-equilibrium dynamics of hard-core bosons confined on optical lattices (United States)

    Rigol, Marcos; Muramatsu, Alejandro


    We study by means of an exact approach, a gas of hard core bosons (HCB) confined on optical lattices. The ground state properties of such systems are analyzed. Local incompressible phases appear in the system, like in the case of interacting soft-core bosons [1] and fermions [2,3]. The changes in momentum distribution function and in the natural orbitals (effective single particle states) introduced by the formation of such phases are analyzed. We also study non-equilibrium properties for those systems, which within our numerical approach can be obtained exactly for systems with 200 particles on lattices with 3000 sites. In particular we analyze the free expansion of the gas when it is released from the trap turning off the confining potential. We show that the expansion is non-trivial (as opposed to the fermionic case) and new features to be observed in the experiments are analyzed. [1] G. G. Batrouni, V. Rousseau, R. T. Scalettar, M. Rigol, A. Muramatsu, P. J. H. Denteneer, and M. Troyer, Phys. Rev. Lett. 89, 117203 (2002). [2] M. Rigol, A. Muramatsu, G. G. Batrouni, and R. T. Scalettar, Phys. Rev. Lett. 91, 130403 (2003). [3] M. Rigol and A. Muramatsu, cond-mat/0309670 (2003).

  15. Unifying Role of Radial Electric Field Shear in the Confinement Trends of TFTR Supershot Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, D.R.; Scott, S.D. [Princeton University Plasma Physics Laboratory, P.O.B. 451, Princeton, New Jersey 08543 (United States); Coppi, B.; Porkolab, M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    A model is presented to explain the favorable ion thermal confinement trends of supershot plasmas in the Tokamak Fusion Test Reactor (TFTR). Turbulence suppression by radial electric field shear is important to reproduce the measured temperatures. Supershot confinement scalings are reproduced in more than sixty discharges, including favorable core power scaling and variation with isotopic mass, density peakedness, edge recycling, and toroidal rotation. The results connect the transitionless supershot regime with improved confinement regimes which are attained through sharp confinement transitions in the core or edge. {copyright} {ital 1998} {ital The American Physical Society}

  16. Carbon Dioxide Transport and Sorption Behavior in Confined Coal Cores for Enhanced Coalbed Methane and CO2 Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jikich, S.A.; McLendon, T.R.; Seshadri, K.S.; Irdi, G.A.; Smith, D.H.


    Measurements of sorption isotherms and transport properties of CO2 in coal cores are important for designing enhanced coalbed methane/CO2 sequestration field projects. Sorption isotherms measured in the lab can provide the upper limit on the amount of CO2 that might be sorbed in these projects. Because sequestration sites will most likely be in unmineable coals, many of the coals will be deep and under considerable lithostatic and hydrostatic pressures. These lithostatic pressures may significantly reduce the sorption capacities and/or transport rates. Consequently, we have studied apparent sorption and diffusion in a coal core under confining pressure. A core from the important bituminous coal Pittsburgh #8 was kept under a constant, three-dimensional external stress; the sample was scanned by X-ray computer tomography (CT) before, then while it sorbed, CO2. Increases in sample density due to sorption were calculated from the CT images. Moreover, density distributions for small volume elements inside the core were calculated and analyzed. Qualitatively, the computerized tomography showed that gas sorption advanced at different rates in different regions of the core, and that diffusion and sorption progressed slowly. The amounts of CO2 sorbed were plotted vs. position (at fixed times) and vs. time (for various locations in the sample). The resulting sorption isotherms were compared to isotherms obtained from powdered coal from the same Pittsburgh #8 extended sample. The results showed that for this single coal at specified times, the apparent sorption isotherms were dependent on position of the volume element in the core and the distance from the CO2 source. Also, the calculated isotherms showed that less CO2 was sorbed than by a powdered (and unconfined) sample of the coal. Changes in density distributions during the experiment were also observed. After desorption, the density distribution of calculated volume elements differed from the initial distribution

  17. Access to high-confinement regimes on Alcator C-Mod and the complex influence of divertor geometry (United States)

    Hughes, J. W.; Labombard, B.; Brunner, D.; Hubbard, A.; Terry, J.; Rice, J.; Walk, J.; Cziegler, I.; Edlund, E.; Theiler, C.


    Placement of X-points and strike points in a diverted tokamak can have a remarkable impact on plasma properties, including thermal and particle confinement. The distinctive divertor of Alcator C-Mod allows substantial variation of divertor leg length, field line attack angle and divertor baffling, allowing us to induce changes in both L-mode confinement and access to both H-mode and I-mode. With the ion ∇B drift directed toward the divertor, scanning the strike point can induce ~ 2 × reductions in H-mode power threshold, and can produce a window for I-mode operation with H98 > 1 . Detailed high-resolution measurements, spanning the last closed flux surface, provide profiles of key quantities (n, T, ϕ) and their gradients, which are of likely importance in determining whether a discharge evolves an edge transport barrier, or remains in an L-mode state. Advances in Langmuir probes have enabled characterization of both radial profiles and fast (power is approached. These data allow new tests of models for H-mode access, especially those attempting to explain the non-monotonic density dependence of the H-mode power threshold through changes in transport and/or turbulence. Supported by U.S. Department of Energy award DE-FC02-99ER54512, using Alcator C-Mod, a DOE Office of Science User Facility.

  18. Core conditions for alpha heating attained in direct-drive inertial confinement fusion. (United States)

    Bose, A; Woo, K M; Betti, R; Campbell, E M; Mangino, D; Christopherson, A R; McCrory, R L; Nora, R; Regan, S P; Goncharov, V N; Sangster, T C; Forrest, C J; Frenje, J; Gatu Johnson, M; Glebov, V Yu; Knauer, J P; Marshall, F J; Stoeckl, C; Theobald, W


    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  19. The Conservation Equations for a Magnetically Confined Gas Core Nuclear Rocket (United States)

    Kammash, Terry; Galbraith, David L.


    A very promising propulsion scheme that could meet the objectives of the Space Exploration Initiative (SEI) of sending manned missions to Mars in the early part of the next century is the open-cycle Gas Core (GCR) Nuclear Rocket. Preliminary assessments of the performance of such advice indicate that specific impulses of several thousand seconds, and thrusts of hundreds of kilonewtons are possible. These attractive propulsion parameters are obtained because the hydrogen propellant gets heated to very high temperatures by the energy radiated from a critical uranium core which is in the form of a plasma generated under very high pressure. Because of the relative motion between the propellant and the core, certain types of hydrodynamic instabilities can occur, and result in rapid escape of the fuel through the nozzle. One effective way of dealing with this instability is to place the system in an externally applied magnetic field. In this paper we formulate the appropriate conservation equations that describe the dynamics of GCR in the presence of magnetic fields, and indicate the role such fields play in the performance of the system.

  20. Application of uniaxial confining-core clamp with hydrous pyrolysis in petrophysical and geochemical studies of source rocks at various thermal maturities (United States)

    Lewan, Michael D.; Birdwell, Justin E.; Baez, Luis; Beeney, Ken; Sonnenberg, Steve


    Understanding changes in petrophysical and geochemical parameters during source rock thermal maturation is a critical component in evaluating source-rock petroleum accumulations. Natural core data are preferred, but obtaining cores that represent the same facies of a source rock at different thermal maturities is seldom possible. An alternative approach is to induce thermal maturity changes by laboratory pyrolysis on aliquots of a source-rock sample of a given facies of interest. Hydrous pyrolysis is an effective way to induce thermal maturity on source-rock cores and provide expelled oils that are similar in composition to natural crude oils. However, net-volume increases during bitumen and oil generation result in expanded cores due to opening of bedding-plane partings. Although meaningful geochemical measurements on expanded, recovered cores are possible, the utility of the core for measuring petrophysical properties relevant to natural subsurface cores is not suitable. This problem created during hydrous pyrolysis is alleviated by using a stainless steel uniaxial confinement clamp on rock cores cut perpendicular to bedding fabric. The clamp prevents expansion just as overburden does during natural petroleum formation in the subsurface. As a result, intact cores can be recovered at various thermal maturities for the measurement of petrophysical properties as well as for geochemical analyses. This approach has been applied to 1.7-inch diameter cores taken perpendicular to the bedding fabric of a 2.3- to 2.4-inch thick slab of Mahogany oil shale from the Eocene Green River Formation. Cores were subjected to hydrous pyrolysis at 360 °C for 72 h, which represents near maximum oil generation. One core was heated unconfined and the other was heated in the uniaxial confinement clamp. The unconfined core developed open tensile fractures parallel to the bedding fabric that result in a 38 % vertical expansion of the core. These open fractures did not occur in the

  1. Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

    NARCIS (Netherlands)

    Torruellas, William E.; Krijnen, Gijsbertus J.M.; Kim, Dug Y.; Schiek, Roland; Stegeman, George J.; Vidakovic, Petar; Zyss, Joseph


    The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to

  2. Direct Observation of Confined Acoustic Phonons in the Photoluminescence Spectra of a Single CdSe-CdS-ZnS Core-Shell-Shell Nanocrystal (United States)

    Chilla, Gerwin; Kipp, Tobias; Menke, Torben; Heitmann, Detlef; Nikolic, Marija; Frömsdorf, Andreas; Kornowski, Andreas; Förster, Stephan; Weller, Horst


    We report on the direct observation of confined acoustic phonons in the photoluminescence spectra of single CdSe-CdS-ZnS nanocrystals, whose ligands were exchanged to poly(ethylene oxide) (PEO) before they were embedded in a PEO matrix. Modeling a nanocrystal as an elastic sphere, the confined acoustic modes can be assigned to purely radial vibrations: the breathing mode and its two first radial harmonics. In addition to acoustic modes, we also observe longitudinal optical modes of the core material and, remarkably, also of both shell materials.

  3. Ultrathin Interface Regime of Core-Shell Magnetic Nanoparticles for Effective Magnetism Tailoring. (United States)

    Moon, Seung Ho; Noh, Seung-Hyun; Lee, Jae-Hyun; Shin, Tae-Hyun; Lim, Yongjun; Cheon, Jinwoo


    The magnetic exchange coupling interaction between hard and soft magnetic phases has been important for tailoring nanoscale magnetism, but spin interactions at the core-shell interface have not been well studied. Here, we systematically investigated a new interface phenomenon termed enhanced spin canting (ESC), which is operative when the shell thickness becomes ultrathin, a few atomic layers, and exhibits a large enhancement of magnetic coercivity (HC). We found that ESC arises not from the typical hard-soft exchange coupling but rather from the large magnetic surface anisotropy (KS) of the ultrathin interface. Due to this large increase in magnetism, ultrathin core-shell nanoparticles overreach the theoretical limit of magnetic energy product ((BH)max) and exhibit one of the largest values of specific loss power (SLP), which testifies to their potential capability as an effective mediator of magnetic energy conversion.

  4. Precipitation regime influence on oxygen triple-isotope distributions in Antarctic precipitation and ice cores (United States)

    Miller, Martin F.


    The relative abundance of 17O in meteoric precipitation is usually reported in terms of the 17O-excess parameter. Variations of 17O-excess in Antarctic precipitation and ice cores have hitherto been attributed to normalised relative humidity changes at the moisture source region, or to the influence of a temperature-dependent supersaturation-controlled kinetic isotope effect during in-cloud ice formation below -20 °C. Neither mechanism, however, satisfactorily explains the large range of 17O-excess values reported from measurements. A different approach, based on the regression characteristics of 103 ln (1 +δ17 O) versus 103 ln (1 +δ18 O), is applied here to previously published isotopic data sets. The analysis indicates that clear-sky precipitation ('diamond dust'), which occurs widely in inland Antarctica, is characterised by an unusual relative abundance of 17O, distinct from that associated with cloud-derived, synoptic snowfall. Furthermore, this distinction appears to be largely preserved in the ice core record. The respective mass contributions to snowfall accumulation - on both temporal and spatial scales - provides the basis of a simple, first-order explanation for the observed oxygen triple-isotope ratio variations in Antarctic precipitation, surface snow and ice cores. Using this approach, it is shown that precipitation during the last major deglaciation, both in western Antarctica at the West Antarctic Ice Sheet (WAIS) Divide and at Vostok on the eastern Antarctic plateau, consisted essentially of diamond dust only, despite a large temperature differential (and thus different water vapour supersaturation conditions) at the two locations. In contrast, synoptic snowfall events dominate the accumulation record throughout the Holocene at both sites.

  5. Replica of confined acoustic phonons in the photoluminescence of single CdSe/CdS/ZnS core/shell/shell nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kipp, Tobias; Chilla, Gerwin; Menke, Torben; Heitmann, Detlef [Institut fuer Angewandte Physik, Zentrum fuer Mikrostrukturforschung, Universitaet Hamburg (Germany); Nikolic, Marija; Froemsdorf, Andreas; Kornowski, Andreas; Foerster, Stephan; Weller, Horst [Institut fuer Physikalische Chemie, Universitaet Hamburg (Germany)


    We investigate the photoluminescence (PL) of single CdSe/CdS/ZnS core/shell/shell NCs whose ligands were exchanged to poly(ethylen oxide) (PEO) before they were embedded in a PEO matrix. We find NCs exhibiting a strong and durable PL even under high excitation power. By averaging PL spectra of a single NC, a set of peaks with distinct distance to the zero-phonon line (ZPL) of the NC can be observed. These peaks are attribute to phonon replicas. Most interestingly, by modeling the NC as an elastic sphere and calculating its vibrational modes, we can identify three peaks close to the ZPL as confined acoustic phonon modes: the breathing mode and its two radial harmonics. Other peaks can be assigned to LA and LO phonons of the CdSe core and LO phonons of both the CdS and ZnS shells.

  6. The differential effects of core stabilization exercise regime and conventional physiotherapy regime on postural control parameters during perturbation in patients with movement and control impairment chronic low back pain. (United States)

    Muthukrishnan, Ramprasad; Shenoy, Shweta D; Jaspal, Sandhu S; Nellikunja, Shankara; Fernandes, Svetlana


    The purpose of the present study was to examine the differential effect of core stability exercise training and conventional physiotherapy regime on altered postural control parameters in patients with chronic low back pain (CLBP). As heterogeneity in CLBP population moderates the effect of intervention on outcomes, in this study, interventions approaches were used based on sub-groups of CLBP. This was an allocation concealed, blinded, sequential and pragmatic control trial. Three groups of participants were investigated during postural perturbations: 1) CLBP patients with movement impairment (n = 15, MI group) randomized to conventional physiotherapy regime 2) fifteen CLBP patients with control impairment randomized to core stability group (CI group) and 3) fifteen healthy controls (HC). The MI group did not show any significant changes in postural control parameters after the intervention period however they improved significantly in disability scores and fear avoidance belief questionnaire work score (P 0.8) after 8 weeks of core stability exercises for the adjusted p values. Postural control parameters of HC group were analyzed independently with pre and post postural control parameters of CI and MI group. This revealed the significant improvements in postural control parameters in CI group compared to MI group indicating the specific adaptation to the core stability exercises in CI group. Though the disability scores were reduced significantly in CI and MI groups (p core stability exercise group demonstrated significant improvements after intervention in ground reaction forces (Fz, Mz; g > 0.8) indicating changes in load transfer patterns during perturbation similar to HC group. UTRN095032158-06012009423714.

  7. The differential effects of core stabilization exercise regime and conventional physiotherapy regime on postural control parameters during perturbation in patients with movement and control impairment chronic low back pain

    Directory of Open Access Journals (Sweden)

    Fernandes Svetlana


    Full Text Available Abstract Background The purpose of the present study was to examine the differential effect of core stability exercise training and conventional physiotherapy regime on altered postural control parameters in patients with chronic low back pain (CLBP. As heterogeneity in CLBP population moderates the effect of intervention on outcomes, in this study, interventions approaches were used based on sub-groups of CLBP. Methods This was an allocation concealed, blinded, sequential and pragmatic control trial. Three groups of participants were investigated during postural perturbations: 1 CLBP patients with movement impairment (n = 15, MI group randomized to conventional physiotherapy regime 2 fifteen CLBP patients with control impairment randomized to core stability group (CI group and 3 fifteen healthy controls (HC. Results The MI group did not show any significant changes in postural control parameters after the intervention period however they improved significantly in disability scores and fear avoidance belief questionnaire work score (P 0.8 after 8 weeks of core stability exercises for the adjusted p values. Postural control parameters of HC group were analyzed independently with pre and post postural control parameters of CI and MI group. This revealed the significant improvements in postural control parameters in CI group compared to MI group indicating the specific adaptation to the core stability exercises in CI group. Though the disability scores were reduced significantly in CI and MI groups (p Conclusions In this study core stability exercise group demonstrated significant improvements after intervention in ground reaction forces (Fz, Mz; g > 0.8 indicating changes in load transfer patterns during perturbation similar to HC group. Trial registration UTRN095032158-06012009423714

  8. Photoemission Studies of Si Quantum Dots with Ge Core: Dots formation, Intermixing at Si-clad/Ge-core interface and Quantum Confinement Effect

    Directory of Open Access Journals (Sweden)

    Yudi Darma


    Full Text Available Spherical Si nanocrystallites with Ge core (~20nm in average dot diameter have been prepared by controlling selective growth conditions of low-pressure chemical vapor deposition (LPCVD on ultrathin SiO2 using alternately pure SiH4 and 5% GeH4 diluted with He. XPS results confirm the highly selective growth of Ge on the pregrown Si dots and subsequently complete coverage by Si selective growth on Ge/Si dots. Compositional mixing and the crystallinity of Si dots with Ge core as a function of annealing temperature in the range of 550-800oC has been evaluated by XPS analysis and confirms the diffusion of Ge atoms from Ge core towards the Si clad accompanied by formation of GeOx at the Si clad surface. The first subband energy at the valence band of Si dot with Ge core has been measured as an energy shift at the top of the valence band density of state using XPS. The systematic shift of the valence band maximum towards higher binding energy with progressive deposition in the dot formation indicate the charging effect of dots and SiO2 layer by photoemission during measurements.

  9. Acoustic confinement and Stimulated Brillouin Scattering in integrated optical waveguides

    CERN Document Server

    Poulton, Christopher G; Eggleton, Benjamin J


    We examine the effect of acoustic mode confinement on Stimulated Brillouin Scattering in optical waveguides that consist of a guiding core embedded in a solid substrate. We find that SBS can arise due to coupling to acoustic modes in three different regimes. First, the acoustic modes may be guided by total internal reflection; in this case the SBS gain depends directly on the degree of confinement of the acoustic mode in the core, which is in turn determined by the acoustic V-parameter. Second, the acoustic modes may be leaky, but may nevertheless have a sufficiently long lifetime to have a large effect on the SBS gain; the lifetime of acoustic modes in this regime depends not only on the contrast in acoustic properties between the core and the cladding, but is also highly dependent on the waveguide dimensions. Finally SBS may occur due to coupling to free modes, which exist even in the absence of acoustic confinement; we find that the cumulative effect of coupling to these non-confined modes results in signi...

  10. Demonstration of Confined Electron Gas and Steep-Slope Behavior in Delta-Doped GaAs-AlGaAs Core-Shell Nanowire Transistors. (United States)

    Morkötter, S; Jeon, N; Rudolph, D; Loitsch, B; Spirkoska, D; Hoffmann, E; Döblinger, M; Matich, S; Finley, J J; Lauhon, L J; Abstreiter, G; Koblmüller, G


    Strong surface and impurity scattering in III-V semiconductor-based nanowires (NW) degrade the performance of electronic devices, requiring refined concepts for controlling charge carrier conductivity. Here, we demonstrate remote Si delta (δ)-doping of radial GaAs-AlGaAs core-shell NWs that unambiguously exhibit a strongly confined electron gas with enhanced low-temperature field-effect mobilities up to 5 × 10(3) cm(2) V(-1) s(-1). The spatial separation between the high-mobility free electron gas at the NW core-shell interface and the Si dopants in the shell is directly verified by atom probe tomographic (APT) analysis, band-profile calculations, and transport characterization in advanced field-effect transistor (FET) geometries, demonstrating powerful control over the free electron gas density and conductivity. Multigated NW-FETs allow us to spatially resolve channel width- and crystal phase-dependent variations in electron gas density and mobility along single NW-FETs. Notably, dc output and transfer characteristics of these n-type depletion mode NW-FETs reveal excellent drain current saturation and record low subthreshold slopes of 70 mV/dec at on/off ratios >10(4)-10(5) at room temperature.

  11. Fluctuating monsoonal precipitation as revealed by foraminiferal variations in a core from shelf regime off Karwar (India)

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    Variations in the percentage frequency of the foraminifera Cavarotalia annectens in the sediments collected by box core in the shelf region of Karwar, infront of the mouth of the Kalinadi river, India were used to map paleomonsoonal variations...

  12. Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. V. Nonisothermal Collapse Regime

    Energy Technology Data Exchange (ETDEWEB)

    Boss, Alan P., E-mail: [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)


    Recent meteoritical analyses support an initial abundance of the short-lived radioisotope (SLRI) {sup 60}Fe that may be high enough to require nucleosynthesis in a core-collapse supernova, followed by rapid incorporation into primitive meteoritical components, rather than a scenario where such isotopes were inherited from a well-mixed region of a giant molecular cloud polluted by a variety of supernovae remnants and massive star winds. This paper continues to explore the former scenario, by calculating three-dimensional, adaptive mesh refinement, hydrodynamical code (FLASH 2.5) models of the self-gravitational, dynamical collapse of a molecular cloud core that has been struck by a thin shock front with a speed of 40 km s{sup −1}, leading to the injection of shock front matter into the collapsing cloud through the formation of Rayleigh–Taylor fingers at the shock–cloud intersection. These models extend the previous work into the nonisothermal collapse regime using a polytropic approximation to represent compressional heating in the optically thick protostar. The models show that the injection efficiencies of shock front materials are enhanced compared to previous models, which were not carried into the nonisothermal regime, and so did not reach such high densities. The new models, combined with the recent estimates of initial {sup 60}Fe abundances, imply that the supernova triggering and injection scenario remains a plausible explanation for the origin of the SLRIs involved in the formation of our solar system.

  13. Topology of polymer chains under nanoscale confinement. (United States)

    Satarifard, Vahid; Heidari, Maziar; Mashaghi, Samaneh; Tans, Sander J; Ejtehadi, Mohammad Reza; Mashaghi, Alireza


    Spatial confinement limits the conformational space accessible to biomolecules but the implications for bimolecular topology are not yet known. Folded linear biopolymers can be seen as molecular circuits formed by intramolecular contacts. The pairwise arrangement of intra-chain contacts can be categorized as parallel, series or cross, and has been identified as a topological property. Using molecular dynamics simulations, we determine the contact order distributions and topological circuits of short semi-flexible linear and ring polymer chains with a persistence length of lp under a spherical confinement of radius Rc. At low values of lp/Rc, the entropy of the linear chain leads to the formation of independent contacts along the chain and accordingly, increases the fraction of series topology with respect to other topologies. However, at high lp/Rc, the fraction of cross and parallel topologies are enhanced in the chain topological circuits with cross becoming predominant. At an intermediate confining regime, we identify a critical value of lp/Rc, at which all topological states have equal probability. Confinement thus equalizes the probability of more complex cross and parallel topologies to the level of the more simple, non-cooperative series topology. Moreover, our topology analysis reveals distinct behaviours for ring- and linear polymers under weak confinement; however, we find no difference between ring- and linear polymers under strong confinement. Under weak confinement, ring polymers adopt parallel and series topologies with equal likelihood, while linear polymers show a higher tendency for series arrangement. The radial distribution analysis of the topology reveals a non-uniform effect of confinement on the topology of polymer chains, thereby imposing more pronounced effects on the core region than on the confinement surface. Additionally, our results reveal that over a wide range of confining radii, loops arranged in parallel and cross topologies have

  14. Precipitation and synoptic regime in two extreme years 2009 and 2010 at Dome C, Antarctica - implications for ice core interpretation (United States)

    Schlosser, Elisabeth; Stenni, Barbara; Valt, Mauro; Cagnati, Anselmo; Powers, Jordan G.; Manning, Kevin W.; Raphael, Marilyn; Duda, Michael G.


    At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements were initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM (Southern Annular Mode) index and a negative (positive) ZW3 (zonal wave number three) index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

  15. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin


    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  16. Magnetic confinement

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo (ed.)


    The Frascati Tokamak Upgrade (FTU) is a compact, high-magnetic-field tokamak capable of operating at density and magnetic field values similar to, or even encompassing, those of International Thermonuclear Experimental Reactor (ITER) and therefore provides a unique opportunity to explore physics issues that are directly relevant to ITER. During 2004 the experimental activities were focussed on fully exploiting the lower hybrid system (for generating and controlling the plasma current) and the electron cyclotron heating system (joint experiment with the Institute of Plasma Physics of the National Research Council, Milan). With all four gyrotrons in operation, full electron cyclotron power was achieved up to a record level of 1.5 MW. By simultaneously injecting lower hybrid waves, to tailor the plasma current radial profile, and electron cyclotron waves, to heat the plasma centre, good confinement regimes with internal transport barriers were obtained at the highest plasma density values ever achieved for this operation regime (n {approx}1.5X10{sup 20}m{sup -3}). Specific studies were devoted to optimising the coupling of lower hybrid waves to the plasma (by real-time control of the plasma position) and to generating current by electron cyclotron current drive. The new scanning CO{sub 2} interferometer (developed by the Reversed Field Experiment Consortium) for high spatial and time resolution (1 cm/50 {mu}s) density profile measurements was extensively used. The Thomson scattering diagnostic was upgraded and enabled observation of scattered signals associated with the Confinement background plasma dynamics. As for theoretical studies on the dynamics of turbulence in plasmas, the transition from Bohm-like scaling to gyro-Bohm scaling of the local plasma diffusivity was demonstrated on the basis of a generalised four wave model (joint collaboration with Princeton Plasma Physics Laboratory and the University of California at Irvine). The transition from weak to strong

  17. Plasma confinement

    CERN Document Server

    Hazeltine, R D


    Detailed and authoritative, this volume examines the essential physics underlying international research in magnetic confinement fusion. It offers readable, thorough accounts of the fundamental concepts behind methods of confining plasma at or near thermonuclear conditions. Designed for a one- or two-semester graduate-level course in plasma physics, it also represents a valuable reference for professional physicists in controlled fusion and related disciplines.

  18. Impurities confined in quantum structures

    CERN Document Server

    Holtz, Per Olof


    The introduction of impurities, even in very small concentrations, in a semiconductor can change its optical and electrical properties entirely. This attribute of the semiconductor is utilized in the manifoldness of their applications. In this book, the progress on elucidating the physical properties of impurities confined in quantum structures are reviewed with an emphasis on the experimental aspects. The major results of various kinds of characterization, such as infrared spectroscopy, Raman measurements, luminescence characterization, perturbation spectroscopy and dynamical studies of the confined impurities are reviewed, but also the theoretical basis to calculate the electronic structure of the confined donors and acceptors are presented. This monograph also describes more specific aspects of the confined impurities such as the properties in the high doping regime and the effects of hydrogen passivation.

  19. A Key to Improved Ion Core Confinement in the JET Tokamak: Ion Stiffness Mitigation due to Combined Plasma Rotation and Low Magnetic Shear

    DEFF Research Database (Denmark)

    Mantica, P.; Challis, C.; Peeters, A.G.


    New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. Phys. Rev. Lett. 102 175002 (2009)] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implicatio...

  20. Comparison of electron temperature fluctuations with gyrokinetic sumulations across the ohmic energy confinement transition in Alcator C-Mod (United States)

    Sung, C.; White, A.; Howard, N.; Mikkelsen, D.; Rice, J.; Reinke, M.; Gao, C.; Ennever, P.; Porkolab, M.; Churchill, R.; Theiler, C.; Hubbard, A.; Greenwald, M.


    Long wavelength electron temperature fluctuations (kyρs < 0 . 3) near the edge (r / a ~ 0 . 85) are reduced across the ohmic confinement transition from Linear Ohmic Confinement(LOC) regime to Saturated Ohmic Confinement(SOC) regime in Alcator C-Mod. Linear stability analysis shows that the dominant mode of long wavelength turbulence near the edge is changed from Trapped Electron Mode(TEM) to Ion Temperature Gradient(ITG) mode while the dominant mode is not changed deeper in the core (r / a ~ 0 . 5). This indicates that local turbulence changes near the edge might be responsible for the change of global energy confinement in ohmic plasmas. Further study using nonlinear gyrokinetic simulations is being performed to clarify the relation between the change of local turbulence and global ohmic energy confinement. Through nonlinear gyrokinetic simulation (GYRO), we will investigate the change of fluctuating quantities (T~ , ñ , ϕ~) and their phase relations across ohmic confinement transitions, and relate them to the change of energy transport. A synthetic CECE diagnostic for C-Mod has been developed, and it will be used to validate the gyrokinetic simulations. Research supported by USDoE awards DE-SC0006419, DE-FC02-99ER54512.

  1. The confinement effect in spherical inhomogeneous quantum dots and stability of excitons

    Directory of Open Access Journals (Sweden)

    F. Benhaddou


    Full Text Available We investigate in this work the quantum confinement effect of exciton in spherical inhomogeneous quantum dots IQDs. The spherical core is enveloped by two shells. The inner shell is a semiconductor characterized by a small band-gap. The core and the outer shell are the same semiconductor characterized by a large band-gap. So there is a significant gap-offset creating a deep potential well where the excitons are localized and strongly confined. We have adopted the Ritz variational method to calculate numerically the excitonic ground state energy and its binding energy in the strong, moderate and low confinement regimes. The results show that the Ritz variational method is in good agreement with the perturbation method in strong confinement. There is a double confinement effect and dual control. The calculation checks the effective Rydberg R* at the asymptotic limit of bulk semiconductor when the thickness takes very large values. The excitonic binding energy increases, Thus giving the excitons a high stability even at ambient temperature. These nanosystems are promising in several applications: lighting, detection, biological labeling and quantum computing.

  2. The confinement effect in spherical inhomogeneous quantum dots and stability of excitons (United States)

    Benhaddou, F.; Zorkani, I.; Jorio, A.


    We investigate in this work the quantum confinement effect of exciton in spherical inhomogeneous quantum dots IQDs. The spherical core is enveloped by two shells. The inner shell is a semiconductor characterized by a small band-gap. The core and the outer shell are the same semiconductor characterized by a large band-gap. So there is a significant gap-offset creating a deep potential well where the excitons are localized and strongly confined. We have adopted the Ritz variational method to calculate numerically the excitonic ground state energy and its binding energy in the strong, moderate and low confinement regimes. The results show that the Ritz variational method is in good agreement with the perturbation method in strong confinement. There is a double confinement effect and dual control. The calculation checks the effective Rydberg R* at the asymptotic limit of bulk semiconductor when the thickness takes very large values. The excitonic binding energy increases, Thus giving the excitons a high stability even at ambient temperature. These nanosystems are promising in several applications: lighting, detection, biological labeling and quantum computing.

  3. Propriedades magnéticas de memória e envelhecimento, exchange bias e treinamento de nanopartículas do tipo core-shell em regimes de interações dipolares fracas e fortes


    Leite, Rodolpho Carvalho


    Investigamos as propriedades magnéticas de nanopartículas core-shell (NPs-CS) ultrapequenas de CoFe2O4@γ-Fe2O3 com diâmetro médio de dRX = 2.7 nm em amostras de ferrofluido diluído e pó compacto. Utilizamos a abordagem proposta por Thamm e Hesse para definir os dois regimes de interações fracas, para amostra de ferrofluido diluído, e fortes, para amostra pó, presentes a 5 K. A energia de anisotropia magnética, nestes regimes, é sondada pela curva de primeira magnetização, dependência térmica ...

  4. Modeling of an eddy-current ferrite-cored probe response in time harmonic regime; Modelisation de la reponse d'un capteur a courants de Foucault comportant un noyau ferromagnetique en regime harmonique

    Energy Technology Data Exchange (ETDEWEB)

    Buvat, F


    In aeronautics, non destructive evaluation by eddy-current is commonly used to detect corrosion area or cracks in structures. Eddy-current testing by using ferrite-cored probes is effective to detect these kind of defects. So, having a model able to predict these probes responses is a major endeavor. Our work consisted in developing a model determining the ferrite-cored probes response to a defect. To model fields inside both the core and the defect, an integral formulation has been used resulting from the application of the Green theorem onto the equations of propagation. Simulation results have been compared to synthetic data obtained by a finite-element method and they have been validated by comparison with measured impedance data. However as this model may be computationally costly, the use of the so-called non-linear approximation has been tested to tackle the case of long defects. The model has been integrated inside the CIVA platform developed by the CEA. (author)

  5. Aspects of Confinement in Low Dimensions (United States)

    Bhaseen, M. J.; Tsvelik, A. M.

    We briefly review some examples of confinement which arise in condensed matter physics. We focus on two instructive cases: the off-critical Ising model in a magnetic field, and an array of weakly coupled (extended) Hubbard chains in the Wigner crystal phase. In the appropriate regime, the elementary excitations in these 1 + 1 and quasi-one-dimensional systems are confined into `mesons'. Although the models are generically non-integrable, quantum mechanics and form-factor techniques yield valuable information.

  6. Rotation reversal bifurcation and energy confinement saturation in tokamak Ohmic L-mode plasmas. (United States)

    Rice, J E; Cziegler, I; Diamond, P H; Duval, B P; Podpaly, Y A; Reinke, M L; Ennever, P C; Greenwald, M J; Hughes, J W; Ma, Y; Marmar, E S; Porkolab, M; Tsujii, N; Wolfe, S M


    Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-mode plasmas following electron density ramps. For low density discharges, the core rotation is directed cocurrent, and reverses to countercurrent following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm(-1)≤k(θ)≤11 cm(-1) and frequencies above 70 kHz. There is a strong correlation between the reversal density and the density at which the Ohmic L-mode energy confinement changes from the linear to the saturated regime.

  7. Construction of Hierarchically One-Dimensional Core-Shell CNT@Microporous Carbon by Covalent Bond-Induced Surface-Confined Cross-Linking for High-Performance Supercapacitor. (United States)

    Li, Zhenghui; Li, Zhaopeng; Li, Liuqing; Li, Chengfei; Zhong, Weihao; Zhang, Haiyan


    A covalent bond-induced surface-confined cross-linking is reported to construct one-dimensional coaxial CNT@microporous carbon composite (CNT@micro-C). Octaphenyl polyhedral oligomeric silsesquioxane (Ph-POSS) composed of eight phenyls and a -Si8O12 cage was selected as precursor for microporous carbon. The layer-by-layer cross-linking of phenyl anchored Ph-POSS on the surface of CNT; after carbonization and etching of -Si8O12 cages, CNT@micro-C including CNT core and microporous carbon shell was harvested. The thickness of microporous carbon shell can be well tailored from 6.0 to 20.0 nm, and the surface area of CNT@micro-C can reach 1306 m2 g-1. CNT@micro-C combines the structural advantages of CNT and microporous carbon, presenting large surface area, high electrical conductivity, fast ion transfer speed, and short ion transfer distance. When used as electrode material, CNT@micro-C reveals superior supercapacitive performance; for example, its capacitance can reach 243 F g-1 at 0.5 A g-1 and slightly decreases to 209 F g-1 at 10 A g-1, indicating a capacitance retention of 86%. Even at a very high scan rate of 50 A g-1, a high capacitance of 177 F g-1 is retained, giving a capacitance retention of 73%.

  8. Energy confinement scaling from the international stellarator database

    Energy Technology Data Exchange (ETDEWEB)

    Stroth, U. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Murakami, M.; Dory, R.A.; Yamada, H.; Okamura, S.; Sano, F.; Obiki, T.


    An international stellarator database on global energy confinement is presented comprising data from the ATF, CHS and Heliotron E heliotron/torsatrons and the W7-A and W7-AS shearless stellarators. Regression expressions for the energy confinement time are given for the individual devices and the combined dataset. A comparison with tokamak L mode confinement is discussed on the basis of various scaling expressions. In order to make this database available to interested colleagues, the structure of the database and the parameter list are explained in detail. More recent confinement results incorporating data from enhanced confinement regimes such as H mode are reported elsewhere. (author).

  9. Characteristics of high-confinement modes in Alcator C Mod

    Energy Technology Data Exchange (ETDEWEB)

    Snipes, J.A.; Boivin, R.L.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.; Golovato, S.N.; Graf, M.; Granetz, R.S.; Greenwald, M.; Hubbard, A.; Hutchinson, I.H.; Irby, J.; LaBombard, B.; Marmar, E.S.; Niemczewski, A.; OShea, P.; Porkolab, M.; Stek, P.; Takase, Y.; Terry, J.L.; Umansky, M.; Wolfe, S.M. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    The regime of high particle and energy confinement known as the H mode [Phys. Rev. Lett. {bold 49}, 1408 (1982)] has been extended to a unique range of operation for divertor tokamaks up to toroidal fields of nearly 8 T, line-averaged electron densities of 3{times}10{sup 20} m{sup {minus}3}, and surface power densities of nearly 0.6 MW/m{sup 2} in the compact high-field tokamak Alcator C Mod [Phys. Plasmas {bold 1}, 1511 (1994)]. H modes are achieved in Alcator C Mod with Ion Cyclotron Resonant Frequency (ICRF) heating and with Ohmic heating alone without boronization of the all molybdenum tiled first wall. Large increases in charge exchange flux are observed during the H mode over the entire range of energies from 2 to 10 keV. There appears to be an upper limit to the midplane neutral pressure, of about 0.08 Pa above which no H modes have been observed. The plasmas with the best energy confinement have the lowest midplane neutral pressures, below 0.01 Pa. There is an edge electron temperature threshold such that {ital T}{sub {ital e}}{ge}280 eV {plus_minus}40 eV for sustaining the H mode, which is equal at L{endash}H and H{endash}L transitions. The hysteresis in the threshold power between L{endash}H and H{endash}L transitions is less than 25{percent} on average. Both core and edge particle confinement improve by a factor of 2{endash}4 from L mode to H mode. Energy confinement also improves by up to a factor of 2 over L mode. {copyright} {ital 1996 American Institute of Physics.}

  10. Ge/Si core/shell quantum dots in alumina: tuning the optical absorption by the core and shell size

    Directory of Open Access Journals (Sweden)

    Nekić Nikolina


    Full Text Available Ge/Si core/shell quantum dots (QDs recently received extensive attention due to their specific properties induced by the confinement effects of the core and shell structure. They have a type II confinement resulting in spatially separated charge carriers, the electronic structure strongly dependent on the core and shell size. Herein, the experimental realization of Ge/Si core/shell QDs with strongly tunable optical properties is demonstrated. QDs embedded in an amorphous alumina glass matrix are produced by simple magnetron sputtering deposition. In addition, they are regularly arranged within the matrix due to their self-assembled growth regime. QDs with different Ge core and Si shell sizes are made. These core/shell structures have a significantly stronger absorption compared to pure Ge QDs and a highly tunable absorption peak dependent on the size of the core and shell. The optical properties are in agreement with recent theoretical predictions showing the dramatic influence of the shell size on optical gap, resulting in 0.7 eV blue shift for only 0.4 nm decrease at the shell thickness. Therefore, these materials are very promising for light-harvesting applications.

  11. Liquid Spreading under Nanoscale Confinement (United States)

    Checco, Antonio


    Dynamic atomic force microscopy in the noncontact regime is used to study the morphology of a nonvolatile liquid (squalane) as it spreads along wettable nanostripes embedded in a nonwettable surface. Results show that the liquid profile depends on the amount of lateral confinement imposed by the nanostripes, and it is truncated at the microscopic contact line in good qualitative agreement with classical mesoscale hydrodynamics. However, the width of the contact line is found to be significantly larger than expected theoretically. This behavior may originate from small chemical inhomogeneity of the patterned stripes as well as from thermal fluctuations of the contact line.

  12. Limits on rock strength under high confinement (United States)

    Renshaw, Carl E.; Schulson, Erland M.


    Understanding of deep earthquake source mechanisms requires knowledge of failure processes active under high confinement. Under low confinement the compressive strength of rock is well known to be limited by frictional sliding along stress-concentrating flaws. Under higher confinement strength is usually assumed limited by power-law creep associated with the movement of dislocations. In a review of existing experimental data, we find that when the confinement is high enough to suppress frictional sliding, rock strength increases as a power-law function only up to a critical normalized strain rate. Within the regime where frictional sliding is suppressed and the normalized strain rate is below the critical rate, both globally distributed ductile flow and localized brittle-like failure are observed. When frictional sliding is suppressed and the normalized strain rate is above the critical rate, failure is always localized in a brittle-like manner at a stress that is independent of the degree of confinement. Within the high-confinement, high-strain rate regime, the similarity in normalized failure strengths across a variety of rock types and minerals precludes both transformational faulting and dehydration embrittlement as strength-limiting mechanisms. The magnitude of the normalized failure strength corresponding to the transition to the high-confinement, high-strain rate regime and the observed weak dependence of failure strength on strain rate within this regime are consistent with a localized Peierls-type strength-limiting mechanism. At the highest strain rates the normalized strengths approach the theoretical limit for crystalline materials. Near-theoretical strengths have previously been observed only in nano- and micro-scale regions of materials that are effectively defect-free. Results are summarized in a new deformation mechanism map revealing that when confinement and strain rate are sufficient, strengths approaching the theoretical limit can be achieved in

  13. Physics of magnetic confinement fusion

    Directory of Open Access Journals (Sweden)

    Wagner F.


    Full Text Available Fusion is the energy source of the universe. The local conditions in the core of the Sun allow the transfer of mass into energy, which is finally released in the form of radiation. Technical fusion melts deuterons and tritons to helium releasing large amounts of energy per fusion process. Because of the conditions for fusion, which will be deduced, the fusion fuel is in the plasma state. Here we report on the confinement of fusion plasmas by magnetic fields. Different confinement concepts — tokamaks and stellarators — will be introduced and described. The first fusion reactor, ITER, and the most modern stellarator, Wendelstein 7-X, are under construction. Their basic features and objectives will be presented.

  14. Cascading electron and hole transfer dynamics in a CdS/CdTe core-shell sensitized with bromo-pyrogallol red (Br-PGR): slow charge recombination in type II regime (United States)

    Maity, Partha; Debnath, Tushar; Chopra, Uday; Ghosh, Hirendra Nath


    Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br-PGR using transient absorption spectroscopy and the charge recombination dynamics have been compared with those of CdS/Br-PGR composite materials. Steady state optical absorption studies suggest that Br-PGR forms strong charge transfer (CT) complexes with both the CdS QD and CdS/CdTe core-shell. Hole transfer from the photo-excited QD and QD core-shell to Br-PGR was confirmed by both steady state and time-resolved emission spectroscopy. Charge separation was also confirmed by detecting electrons in the conduction band of the QD and the cation radical of Br-PGR as measured from femtosecond transient absorption spectroscopy. Charge separation in the CdS/Br-PGR composite materials was found to take place in three different pathways, by transferring the photo-excited hole of CdS to Br-PGR, electron injection from the photo-excited Br-PGR to the CdS QD, and direct electron transfer from the HOMO of Br-PGR to the conduction band of the CdS QD. However, in the CdS/CdTe/Br-PGR system hole transfer from the photo-excited CdS to Br-PGR and electron injection from the photo-excited Br-PGR to CdS take place after cascading through the CdTe shell QD. Charge separation also takes place via direct electron transfer from the Br-PGR HOMO to the conduction band of CdS/CdTe. Charge recombination (CR) dynamics between the electron in the conduction band of the CdS QD and the Br-PGR cation radical were determined by monitoring the bleach recovery kinetics. The CR dynamics were found to be much slower in the CdS/CdTe/Br-PGR system than in the CdS/Br-PGR system. The formation of the strong CT complex and the separation of charges cascading through the CdTe shell help to slow down charge recombination in the type II regime.Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br

  15. Structural behavior of supercritical fluids under confinement (United States)

    Ghosh, Kanka; Krishnamurthy, C. V.


    The existence of the Frenkel line in the supercritical regime of a Lennard-Jones (LJ) fluid shown through molecular dynamics (MD) simulations initially and later corroborated by experiments on argon opens up possibilities of understanding the structure and dynamics of supercritical fluids in general and of the Frenkel line in particular. The location of the Frenkel line, which demarcates two distinct physical states, liquidlike and gaslike within the supercritical regime, has been established through MD simulations of the velocity autocorrelation (VACF) and radial distribution function (RDF). We, in this article, explore the changes in the structural features of supercritical LJ fluid under partial confinement using atomistic walls. The study is carried out across the Frenkel line through a series of MD simulations considering a set of thermodynamics states in the supercritical regime (P =5000 bar, 240 K ≤T ≤1500 K ) of argon well above the critical point. Confinement is partial, with atomistic walls located normal to z and extending to "infinity" along the x and y directions. In the "liquidlike" regime of the supercritical phase, particles are found to be distributed in distinct layers along the z axis with layer spacing less than one atomic diameter and the lateral RDF showing amorphous-like structure for specific spacings (packing frustration) and non-amorphous-like structure for other spacings. Increasing the rigidity of the atomistic walls is found to lead to stronger layering and increased structural order. For confinement with reflective walls, layers are found to form with one atomic diameter spacing and the lateral RDF showing close-packed structure for the smaller confinements. Translational order parameter and excess entropy assessment confirms the ordering taking place for atomistic wall and reflective wall confinements. In the "gaslike" regime of the supercritical phase, particle distribution along the spacing and the lateral RDF exhibit features

  16. Physics and performance of the I-mode regime over an expanded operating space on Alcator C-Mod (United States)

    Hubbard, A. E.; Baek, S.-G.; Brunner, D.; Creely, A. J.; Cziegler, I.; Edlund, E.; Hughes, J. W.; LaBombard, B.; Lin, Y.; Liu, Z.; Marmar, E. S.; Reinke, M. L.; Rice, J. E.; Sorbom, B.; Sung, C.; Terry, J.; Theiler, C.; Tolman, E. A.; Walk, J. R.; White, A. E.; Whyte, D.; Wolfe, S. M.; Wukitch, S.; Xu, X. Q.; the Alcator C-Mod Team


    New results on the I-mode regime of operation on the Alcator C-Mod tokamak are reported. This ELM-free regime features high energy confinement and a steep temperature pedestal, while particle confinement remains at L-mode levels, giving stationary density and avoiding impurity accumulation. I-mode has now been obtained over nearly all of the magnetic fields and currents possible in this high field tokamak (I p 0.55-1.7 MA, B T 2.8-8 T) using a configuration with B  ×  ∇ B drift away from the X-point. Results at 8 T confirm that the L-I power threshold varies only weakly with B T, and that the power range for I-mode increases with B T; no 8 T discharges transitioned to H-mode. Parameter dependences of energy confinement are investigated. Core transport simulations are giving insight into the observed turbulence reduction, profile stiffness and confinement improvement. Pedestal models explain the observed stability to ELMs, and can simulate the observed weakly coherent mode. Conditions for I-H transitions have complex dependences on density as well as power. I-modes have now been maintained in near-DN configurations, leading to improved divertor power flux sharing. Prospects for I-mode on future fusion devices such as ITER and ARC are encouraging. Further experiments on other tokamaks are needed to improve confidence in extrapolation.

  17. Inhomogeneous dynamics in confined water nanodroplets (United States)

    Dokter, Adriaan M.; Woutersen, Sander; Bakker, Huib J.


    The effect of confinement on the dynamical properties of liquid water was studied by mid-infrared ultrafast pump–probe spectroscopy on HDO:D2O in reverse micelles. By preparing water-containing reverse micelles of different well defined sizes, we varied the degree of geometric confinement in water nanodroplets with radii ranging from 0.2 to 4.5 nm. We find that water molecules located near the interface confining the droplet exhibit slower vibrational energy relaxation and have a different spectral absorption than those located in the droplet core. As a result, we can measure the orientational dynamics of these different types of water with high selectivity. We observe that the water molecules in the core show similar orientational dynamics as bulk water and that the water layer solvating the interface is highly immobile. PMID:17028175

  18. Confinement in Wendelstein 7-X limiter plasmas (United States)

    Hirsch, M.; Dinklage, A.; Alonso, A.; Fuchert, G.; Bozhenkov, S.; Höfel, U.; Andreeva, T.; Baldzuhn, J.; Beurskens, M.; Bosch, H.-S.; Beidler, C. D.; Biedermann, C.; Blanco, E.; Brakel, R.; Burhenn, R.; Buttenschön, B.; Cappa, A.; Czarnecka, A.; Endler, M.; Estrada, T.; Fornal, T.; Geiger, J.; Grulke, O.; Harris, J. H.; Hartmann, D.; Jakubowski, M.; Klinger, T.; Knauer, J.; Kocsis, G.; König, R.; Kornejew, P.; Krämer-Flecken, A.; Krawczyk, N.; Krychowiak, M.; Kubkowska, M.; Ksiazek, I.; Langenberg, A.; Laqua, H. P.; Lazerson, S.; Maaßberg, H.; Marushchenko, N.; Marsen, S.; Moncada, V.; Moseev, D.; Naujoks, D.; Otte, M.; Pablant, N.; Pasch, E.; Pisano, F.; Rahbarnia, K.; Schröder, T.; Stange, T.; Stephey, L.; Szepesi, T.; Pedersen, T. Sunn; Trimino Mora, H.; Thomsen, H.; Tsuchiya, H.; Turkin, Yu.; Wauters, T.; Weir, G.; Wenzel, U.; Werner, A.; Wolf, R.; Wurden, G. A.; Zhang, D.; the W7-X Team


    Observations on confinement in the first experimental campaign on the optimized Stellarator Wendelstein 7-X are summarized. In this phase W7-X was equipped with five inboard limiters only and thus the discharge length restricted to avoid local overheating. Stationary plasmas are limited to low densities  <2-3 · 1019 m-3. With the available 4.3 MW ECR Heating core T e ~ 8 keV, T i ~ 1-2 keV are achieved routinely resulting in energy confinement time τ E between 80 ms to 150 ms. For these conditions the plasmas show characteristics of core electron root confinement with peaked T e-profiles and positive E r up to about half of the minor radius. Profiles and plasma currents respond to on- and off-axis heating and co- and counter ECCD respectively.

  19. Scanning gate imaging in confined geometries


    Steinacher, R.; Kozikov, A. A.; Rössler, C.; Reichl, C.; Wegscheider, W.; Ensslin, K.; Ihn, T.


    This article reports on tunable electron backscattering investigated with the biased tip of a scanning force microscope. Using a channel defined by a pair of Schottky gates, the branched electron flow of ballistic electrons injected from a quantum point contact is guided by potentials of a tunable height well below the Fermi energy. The transition from injection into an open two-dimensional electron gas to a strongly confined channel exhibits three experimentally distinct regimes: one in whic...

  20. A dynamical model for plasma confinement transitions (United States)

    Pilarczyk, Paweł; García, Luis; Carreras, Benjamin A.; Llerena, Irene


    A three-equation model describing the evolution of the turbulence level, averaged shear flow and sheared zonal flow is analyzed using topological properties of the asymptotic solutions. An exploration in parameter space is done, identifying the attractor sets, which are fixed points and limit cycles. Then a more detailed analysis of all Morse sets is conducted using topological-combinatorial computations. This model allows the description of different types of transitions to improved plasma confinement regimes.

  1. Equilibrium partitioning of macromolecules in confining geometries: Improved universality with a new molecular size parameter

    DEFF Research Database (Denmark)

    Wang, Yanwei; Peters, Günther H.J.; Hansen, Flemming Yssing


    structures (CABS), allows the computation of equilibrium partition coefficients as a function of confinement size solely based on a single sampling of the configuration space of a macromolecule in bulk. Superior in computational speed to previous computational methods, CABS is capable of handling slits...... parameter for characterization of spatial confinement effects on macromolecules. Results for the equilibrium partition coefficient in the weak confinement regime depend only on the ratio ofR-s to the confinement size regardless of molecular details....

  2. Confinement Aquaculture. Final Report. (United States)

    Delaplaine School District, AR.

    The Delaplaine Agriculture Department Confinement Project, begun in June 1988, conducted a confinement aquaculture program by comparing the growth of channel catfish raised in cages in a pond to channel catfish raised in cages in the Black River, Arkansas. The study developed technology that would decrease costs in the domestication of fish, using…

  3. Dynamics in geometrical confinement

    CERN Document Server

    Kremer, Friedrich


    This book describes the dynamics of low molecular weight and polymeric molecules when they are constrained under conditions of geometrical confinement. It covers geometrical confinement in different dimensionalities: (i) in nanometer thin layers or self supporting films (1-dimensional confinement) (ii) in pores or tubes with nanometric diameters (2-dimensional confinement) (iii) as micelles embedded in matrices (3-dimensional) or as nanodroplets.The dynamics under such conditions have been a much discussed and central topic in the focus of intense worldwide research activities within the last two decades. The present book discusses how the resulting molecular mobility is influenced by the subtle counterbalance between surface effects (typically slowing down molecular dynamics through attractive guest/host interactions) and confinement effects (typically increasing the mobility). It also explains how these influences can be modified and tuned, e.g. through appropriate surface coatings, film thicknesses or pore...

  4. Elastic membranes in confinement. (United States)

    Bostwick, J B; Miksis, M J; Davis, S H


    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and coiled DNA, have fine internal structure in which a membrane (or elastic member) is geometrically 'confined' by another object. Here, the two-dimensional shape of an elastic membrane in a 'confining' box is studied by introducing a repulsive confinement pressure that prevents the membrane from intersecting the wall. The stage is set by contrasting confined and unconfined solutions. Continuation methods are then used to compute response diagrams, from which we identify the particular membrane mechanics that generate mitochondria-like shapes. Large confinement pressures yield complex response diagrams with secondary bifurcations and multiple turning points where modal identities may change. Regions in parameter space where such behaviour occurs are then mapped. © 2016 The Author(s).

  5. Classical confinement and outward convection of impurity ions in the MST RFP

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. T. A.; Den Hartog, D. J.; Mirnov, V. V.; Eilerman, S.; Nornberg, M.; Reusch, J. A.; Sarff, J. S. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Caspary, K. J.; Chapman, B. E.; Parke, E. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Magee, R. M. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Brower, D. L.; Ding, W. X.; Lin, L. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Craig, D. [Physics Department, Wheaton College, Wheaton, Illinois 60187 (United States); Fiksel, G. [Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Laboratory for Laser Energetics, University of Rochester, Rochester, New York (United States)


    Impurity ion dynamics measured with simultaneously high spatial and temporal resolution reveal classical ion transport in the reversed-field pinch. The boron, carbon, oxygen, and aluminum impurity ion density profiles are obtained in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] using a fast, active charge-exchange-recombination-spectroscopy diagnostic. Measurements are made during improved-confinement plasmas obtained using inductive control of tearing instability to mitigate stochastic transport. At the onset of the transition to improved confinement, the impurity ion density profile becomes hollow, with a slow decay in the core region concurrent with an increase in the outer region, implying an outward convection of impurities. Impurity transport from Coulomb collisions in the reversed-field pinch is classical for all collisionality regimes, and analysis shows that the observed hollow profile and outward convection can be explained by the classical temperature screening mechanism. The profile agrees well with classical expectations. Experiments performed with impurity pellet injection provide further evidence for classical impurity ion confinement.

  6. Mass gap without confinement (United States)

    Faedo, Antón F.; Mateos, David; Pravos, David; Subils, Javier G.


    We revisit a one-parameter family of three-dimensional gauge theories with known supergravity duals. We show that three infrared behaviors are possible. For generic values of the parameter, the theories exhibit a mass gap but no confinement, meaning no linear quark-antiquark potential; for one limiting value of the parameter the theory flows to an infrared fixed point; and for another limiting value it exhibits both a mass gap and confinement. Theories close to these limiting values exhibit quasi-conformal and quasi-confining dynamics, respectively. Eleven-dimensional supergravity provides a simple, geometric explanation of these features.

  7. Nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol


    We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....

  8. Inflation targeting and core inflation


    Julie Smith


    This paper examines the interaction of core inflation and inflation targeting as a monetary policy regime. Interest in core inflation has grown because of inflation targeting. Core inflation is defined in numerous ways giving rise to many potential measures; this paper defines core inflation as the best forecaster of inflation. A cross-country study finds before the start of inflation targeting, but not after, core inflation differs between non-inflation targeters and inflation targeters. Thr...

  9. Electron-hole confinement symmetry in silicon quantum dots

    NARCIS (Netherlands)

    Müller, F.; Mueller, Filipp; Konstantaras, Georgios; Spruijtenburg, P.C.; van der Wiel, Wilfred Gerard; Zwanenburg, Floris Arnoud


    We report electrical transport measurements on a gate-defined ambipolar quantum dot in intrinsic silicon. The ambipolarity allows its operation as either an electron or a hole quantum dot of which we change the dot occupancy by 20 charge carriers in each regime. Electron−hole confinement symmetry is

  10. Confinement Spectroscopy: Probing Single DNA Molecules with Tapered Nanochannels

    DEFF Research Database (Denmark)

    Persson, Karl Fredrik; Utko, Pawel; Reisner, Walter


    We demonstrate a confinement spectroscopy technique capable of probing small conformational changes of unanchored single DNA molecules in a manner analogous to force spectroscopy, in the regime corresponding to femtonewton forces. In contrast to force spectroscopy, various structural forms of DNA...

  11. Framing of regimes and transition strategies

    DEFF Research Database (Denmark)

    Jensen, Jens Stissing


    This article suggests that transition strategies are always formulated in the context of specific representations of the regime and the challenges it faces. It is argued that the framing of a regime affects the envisioning of transition strategies. An analysis of the current development agenda...... for the housing construction sector in Denmark reveals the relevance and impacts of different regime framings. It is proposed that the ability to cope with framing issues as situated and political processes is at the core of the governance of transitions....


    Energy Technology Data Exchange (ETDEWEB)

    Naranjo-Romero, Raúl; Vázquez-Semadeni, Enrique; Loughnane, Robert M. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72, Morelia, Michoacán, 58089, México (Mexico)


    We investigate the Hierarchical Gravitational Fragmentation scenario through numerical simulations of the prestellar stages of the collapse of a marginally gravitationally unstable isothermal sphere immersed in a strongly gravitationally unstable, uniform background medium. The core developes a Bonnor–Ebert (BE)-like density profile, while at the time of singularity (the protostar) formation the envelope approaches a singular-isothermal-sphere (SIS)-like r{sup −2} density profile. However, these structures are never hydrostatic. In this case, the central flat region is characterized by an infall speed, while the envelope is characterized by a uniform speed. This implies that the hydrostatic SIS initial condition leading to Shu's classical inside-out solution is not expected to occur, and therefore neither should the inside-out solution. Instead, the solution collapses from the outside-in, naturally explaining the observation of extended infall velocities. The core, defined by the radius at which it merges with the background, has a time-variable mass, and evolves along the locus of the ensemble of observed prestellar cores in a plot of M/M{sub BE} versus M, where M is the core's mass and M{sub BE} is the critical BE mass, spanning the range from the “stable” to the “unstable” regimes, even though it is collapsing at all times. We conclude that the presence of an unstable background allows a core to evolve dynamically from the time when it first appears, even when it resembles a pressure-confined, stable BE-sphere. The core can be thought of as a ram-pressure confined BE-sphere, with an increasing mass due to the accretion from the unstable background.

  13. Sustainable urban regime adjustments

    DEFF Research Database (Denmark)

    Quitzau, Maj-Britt; Jensen, Jens Stissing; Elle, Morten


    The endogenous agency that urban governments increasingly portray by making conscious and planned efforts to adjust the regimes they operate within is currently not well captured in transition studies. There is a need to acknowledge the ambiguity of regime enactment at the urban scale. This directs...... attention to the transformative implications of conscious strategic maneuvering by incumbent regime actors, when confronting regime structurations. This article provides insight to processes of regime enactment performed by local governments by applying a flow-oriented perspective on regime dynamics......, inspired by Actor-Network Theory to demonstrate that regime incumbent actors can induce gradual regime adjustments at the urban scale. This is done through a case study of an urban development project, where the Municipality of Egedal in Denmark has successfully promoted energy efficient buildings through...

  14. Confinement for More Space

    DEFF Research Database (Denmark)

    Kipnusu, Wycliffe K.; Elsayed, Mohamed; Kossack, Wilhelm


    Broadband dielectric spectroscopy and positron annihilation lifetime spectroscopy are employed to study the molecular dynamics and effective free volume of 2-ethyl-1-hexanol (2E1H) in the bulk state and when confined in unidirectional nanopores with average diameters of 4, 6, and 8 nm. Enhanced α...

  15. Confinement at Large Nc

    NARCIS (Netherlands)

    Hooft, G. 't


    A discussion is given of the confinement mechanism in terms of the Abelian projection scheme, for a general number Nc of colors. There is a difficulty in the Nc to infinity limit that requires a careful treatment, as the charges of the condensing magnetic monopoles tend to infinity. We suggest that

  16. Growing instead of confining (United States)

    Sun, Yang-Kook; Yoon, Chong Seung


    Confining sulfur in high-surface-area carbon is a widely adapted approach in Li-S batteries, but it often results in low sulfur utilization and low energy density. Now, controlled nucleation of discrete Li2S particles on a network of low-surface-area carbon fibres provides a possible solution to the endemic problems of Li-S batteries.

  17. A comparative study on effect of plain-and wavy-wall confinement on ...

    Indian Academy of Sciences (India)

    Keywords. Bluff body; wake; flow separation; wavy-wall confinement; CFD simulation; finite volume method. Abstract. A first attempt is made for identifying the wake characteristics of circular cylinder confined by a wavy wall at laminar flow regime. Numerical study of flow characteristics past circular cylinder with wavy-wall ...

  18. Polymers under Cylindrical Confinement (United States)

    Russell, Thomas


    Anodized alumina oxide (AAO) membranes offer a unique platform to investigate polymers under confinement. AAO membranes have been prepared where the diameters of the nanopores in the membrane have been varied from 8 to 50 nm by varying the anodization conditions. Capillary force is sufficiently large to draw high molecular weight polymers into the membrane, producing either nanotubes or nanorods. Polymer solutions can also be used place a thin film on the walls of the nanopores, forming nanotubes. With pore diameters less than the radius of gyration, a quantitative understanding of perturbations to chain dynamics due to geometric constraints was examined. We found a weak molecular weight-dependent mobility of polymers confined within AAO nanopores having diameters smaller than the dimension of the chains in the bulk. The measured mobility of polymers in the confined geometry was much higher than the mobility of the unconfined chain. Rayleigh instabilities in thin polymer films confined within nanoporous alumina membranes were also found where periodic undulations on the film surface were found to increase with time, eventually bridging across the cylindrical nanopore, resulting in the formation of polymer nanorods with a periodic array of encapsulated holes. With microphase separated block copolymers, where the characteristic period of the BCP morphology is comparable to the pore diameter, significant deviations from the bulk morphology as revealed by electron tomography. Small angle neutron scattering was also used to investigate the influence of cylindrical confinement on the order-to-disordered transition. This work was done in collaboration with T. J. McCarthy (UMass), K. Shin (Seoul National University), H. Jinnai (Kyoto University), D. Chen, J. Chen, H. Xiang, T. Kim, and P. Dobriyal, and was supported by the DOE, NSF MRSEC, NSF CHM.

  19. Diffusion of Finite-Size Particles in Confined Geometries

    KAUST Repository

    Bruna, Maria


    The diffusion of finite-size hard-core interacting particles in two- or three-dimensional confined domains is considered in the limit that the confinement dimensions become comparable to the particle\\'s dimensions. The result is a nonlinear diffusion equation for the one-particle probability density function, with an overall collective diffusion that depends on both the excluded-volume and the narrow confinement. By including both these effects, the equation is able to interpolate between severe confinement (for example, single-file diffusion) and unconfined diffusion. Numerical solutions of both the effective nonlinear diffusion equation and the stochastic particle system are presented and compared. As an application, the case of diffusion under a ratchet potential is considered, and the change in transport properties due to excluded-volume and confinement effects is examined. © 2013 Society for Mathematical Biology.

  20. Confinement in a planar waveguide with porous silicon omnidirectional mirrors as confining walls

    Energy Technology Data Exchange (ETDEWEB)

    Xifre-Perez, E. [Departament d' Enginyeria Electronica, Electrica i Automatica, ETSE, Campus Sescelades, Universitat Rovira i Virgili, Avda. Paisos Catalans 26, 43007 Tarragona (Spain); Marsal, L.F. [Departament d' Enginyeria Electronica, Electrica i Automatica, ETSE, Campus Sescelades, Universitat Rovira i Virgili, Avda. Paisos Catalans 26, 43007 Tarragona (Spain)]. E-mail:; Ferre-Borrull, J. [Departament d' Enginyeria Electronica, Electrica i Automatica, ETSE, Campus Sescelades, Universitat Rovira i Virgili, Avda. Paisos Catalans 26, 43007 Tarragona (Spain); Pallares, J. [Departament d' Enginyeria Electronica, Electrica i Automatica, ETSE, Campus Sescelades, Universitat Rovira i Virgili, Avda. Paisos Catalans 26, 43007 Tarragona (Spain)


    We present the design and study of waveguide structures based on porous silicon where the light confinement is not due to the usual total reflection effect but to the use of photonic crystals (PCs) as confining walls. These PC are omnidirectional mirrors (OMs), consisting of the periodic repetition of two porous silicon layers with different refractive indices and thicknesses. They reflect the radiation for all angles of incidence within a frequency range called the omnidirectional band gap (OBG). We have followed the PC formalism to investigate the properties of the OM as a multimode waveguide: the number of modes within the band gap, their field spatial distribution and their confinement as a function of the frequency and the core thickness.

  1. Preferential Regimes Can Make Tax Competition Less Harmful


    Keen, Michael


    A key feature of the recent EU and OECD standards for good behavior in international taxation is a presumption against preferential tax regimes (such as those offering advantageous treatment to non-residents or enterprises not active in the domestic market), which are seen as especially corrosive forms of tax competition. This paper shows that, on the contrary, preferential regimes may serve a useful strategic purpose in enabling countries to confine their most aggressive tax competition to p...

  2. Comparison between measured and predicted turbulence frequency spectra in ITG and TEM regimes (United States)

    Citrin, J.; Arnichand, H.; Bernardo, J.; Bourdelle, C.; Garbet, X.; Jenko, F.; Hacquin, S.; Pueschel, M. J.; Sabot, R.


    The observation of distinct peaks in tokamak core reflectometry measurements—named quasi-coherent-modes (QCMs)—are identified as a signature of trapped-electron-mode (TEM) turbulence (Arnichand et al 2016 Plasma Phys. Control. Fusion 58 014037). This phenomenon is investigated with detailed linear and nonlinear gyrokinetic simulations using the Gene code. A Tore-Supra density scan is studied, which traverses through a linear (LOC) to saturated (SOC) ohmic confinement transition. The LOC and SOC phases are both simulated separately. In the LOC phase, where QCMs are observed, TEMs are robustly predicted unstable in linear studies. In the later SOC phase, where QCMs are no longer observed, ion-temperature-gradient (ITG) modes are identified. In nonlinear simulations, in the ITG (SOC) phase, a broadband spectrum is seen. In the TEM (LOC) phase, a clear emergence of a peak at the TEM frequencies is seen. This is due to reduced nonlinear frequency broadening of the underlying linear modes in the TEM regime compared with the ITG regime. A synthetic diagnostic of the nonlinearly simulated frequency spectra reproduces the features observed in the reflectometry measurements. These results support the identification of core QCMs as an experimental marker for TEM turbulence.

  3. Inertial Confinement fusion targets (United States)

    Hendricks, C. D.


    Inertial confinement fusion (ICF) targets are made as simple flat discs, as hollow shells or as complicated multilayer structures. Many techniques were devised for producing the targets. Glass and metal shells are made by using drop and bubble techniques. Solid hydrogen shells are also produced by adapting old methods to the solution of modern problems. Some of these techniques, problems, and solutions are discussed. In addition, the applications of many of the techniques to fabrication of ICF targets is presented.

  4. Confinement for Active Objects


    Florian Kammuller


    In this paper, we provide a formal framework for the security of distributed active objects. Active objects com-municate asynchronously implementing method calls via futures. We base the formal framework on a security model that uses a semi-lattice to enable multi-lateral security crucial for distributed architectures. We further provide a security type system for the programming model ASPfun of functional active objects. Type safety and a confinement property are presented. ASPfun thus reali...

  5. Diagnostic performance of power doppler and ultrasound contrast agents in early imaging-based diagnosis of organ-confined prostate cancer: Is it possible to spare cores with contrast-guided biopsy?

    Energy Technology Data Exchange (ETDEWEB)

    Delgado Oliva, F., E-mail:; Arlandis Guzman, S.; Bonillo García, M.; Broseta Rico, E.; Boronat Tormo, F.


    Objectives: To evaluate the diagnostic performance of gray scale transrectal ultrasound-B-mode US (BMUS), power Doppler (PDUS), and sonographic contrast (CEUS) in early imaging-based diagnosis of localized prostate cancer (PCa) and to compare the diagnostic profitability of randomized biopsy (RB), US-targeted prostate biopsy by means of PDUS and CEUS. Material and methods: A single-center, prospective, transversal, epidemiological study was conducted from January 2010 to January 2014. We consecutively included patients who an imaging study of the prostate with BMUS, PDUS, and CEUS was performed, followed by prostate biopsy due to clinical suspicion of prostate cancer (PSA 4–20 ng/mL and/or rectal exam suggestive of malignancy). The diagnostic performance of BMUS, PDUS, and CEUS was determined by calculating the Sensitivity (S), Specificity (Sp), Predictive values (PV), and diagnostic odds ratio (OR) of the diagnosis tests and, for these variables, in the population general and based on their clinical stage according to rectal exam (cT1 and cT2). PCa detection rates determined by means of a randomized 10-core biopsy scheme were compared with detection rates of CEUS-targeted (SonoVue) 2-core biopsies. Results: Of the initial 984 patients, US contrast SonoVue was administered to 179 (18.2%). The PCa detection rate by organ of BMUS/PDUS in the global population was 38% versus 43% in the subpopulation with CEUS. The mean age of the patients was 64.3 ± 7.01 years (95% CI, 63.75–64.70); mean total PSA was 8.9 ± 3.61 ng/mL (95% CI, 8.67–9.13) and the mean prostate volume was 56.2 ± 29 cc (95% CI, 54.2–58.1). The detection rate by organ of targeted biopsy with BMUS, PDUS, and CEUS were as follows: Global population (10.6, 8.2, 24.5%), stage cT1 (5.6, 4.2, 16.4%), and stage cT2 (32.4, 22.3, 43.5%). Comparing the detection rates of the CEUS-targeted biopsy and randomized biopsy, the following results were obtained: Global population (24.5% vs. 41.8%), stage cT1 (16

  6. Confinement Contains Condensates

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; Roberts, Craig D.; Shrock, Robert; Tandy, Peter C.


    Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have commonly been viewed as constant empirical mass-scales that fill all spacetime, are instead wholly contained within hadrons; i.e., they are a property of hadrons themselves and expressed, e.g., in their Bethe-Salpeter or light-front wave functions. We explain that this paradigm is consistent with empirical evidence, and incidentally expose misconceptions in a recent Comment.

  7. Working under confinement (United States)

    Malgaretti, P.; Pagonabarraga, I.; Rubi, J. M.


    We analyze the performance of a Brownian ratchet in the presence of geometrical constraints. A two-state model that describes the kinetics of molecular motors is used to characterize the energetic cost when the motor proceeds under confinement, in the presence of an external force. We show that the presence of geometrical constraints has a strong effect on the performance of the motor. In particular, we show that it is possible to enhance the ratchet performance by a proper tuning of the parameters characterizing the environment. These results open the possibility of engineering entropically-optimized transport devices.

  8. Hadrosynthesis and Quark Confinement

    Directory of Open Access Journals (Sweden)

    Satz Helmut


    Full Text Available Multihadron production in high energy collisions, from e+e− annihilation to heavy ion interactions, shows remarkable thermal behaviour, specified by a universal “Hagedorn” temperature. We argue that this hadronic radiation is formed by tunnelling through the event horizon of colour confinement, i.e., that it is the QCD counterpart of Hawking-Unruh radiation from black holes. It is shown to be emitted at a universal temperature TH ≃ (σ/2π1/2, where σ denotes the string tension. Since the event horizon does not allow information transfer, the radiation is thermal “at birth”.

  9. Confinement and 4-manifolds

    CERN Multimedia

    CERN. Geneva


    In this talk I will survey a connection between two very challenging problems, one in physics and one in math. The physics problem involves quantitative understanding of confinement in a system with least amount of supersymmetry that has been studied so far and that has a wide range of applications, from semi-realistic string models to qualitatively new examples of gauge-gravity duality. Surprisingly, the rich physics of this system translates into incredibly rich mathematics of the only remaining unsolved case of the Poincare conjecture.

  10. Confined Water: Structure, Dynamics, and Thermodynamics. (United States)

    Chakraborty, Sudip; Kumar, Hemant; Dasgupta, Chandan; Maiti, Prabal K


    a speedup of orientational dynamics. The orientational relaxation of confined water molecules proceeds by angular jumps between two locally stable states, making the relaxation qualitatively different from that expected in the diffusive limit. The spontaneous entry of water inside the hydrophobic cavity of CNTs is primarily driven by an increase in the rotational entropy of water molecules inside the cavity, arising from a reduction in the average number of hydrogen bonds attached to a water molecule. From simulations using a variety of water models, we demonstrate that the relatively simple SPC/E water model yields results in close agreement with those obtained from polarizable water models. Finally, we provide an account of the structure and thermodynamics of water confined in the slit pore between two GO sheets with both oxidized and reduced parts. We show that the potential of mean force for the oxidized part of GO sheets in the presence of water exhibits two local minima, one corresponding to a dry cavity and the other corresponding to a fully hydrated cavity. The coexistence of these two regimes provides permeation pathways for water in GO membranes.

  11. Polymer Conformation under Confinement

    Directory of Open Access Journals (Sweden)

    Stavros Bollas


    Full Text Available The conformation of polymer chains under confinement is investigated in intercalated polymer/layered silicate nanocomposites. Hydrophilic poly(ethylene oxide/sodium montmorillonite, PEO/Na+-MMT, hybrids were prepared utilizing melt intercalation with compositions where the polymer chains are mostly within the ~1 nm galleries of the inorganic material. The polymer chains are completely amorphous in all compositions even at temperatures where the bulk polymer is highly crystalline. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR is utilized to investigate the conformation of the polymer chains over a broad range of temperatures from below to much higher than the bulk polymer melting temperature. A systematic increase of the gauche conformation relatively to the trans is found with decreasing polymer content both for the C–C and the C–O bonds that exist along the PEO backbone indicating that the severe confinement and the proximity to the inorganic surfaces results in a more disordered state of the polymer.

  12. Small Business Tax Regimes


    Yilmaz, Fatih; Coolidge, Jacqueline


    Simplified tax regimes for micro and small enterprises in developing countries are intended to facilitate voluntary tax compliance. However, survey evidence suggests that small business taxation based on simplified bookkeeping or turnover is sometimes perceived as too complex for microenterprises in countries with high illiteracy levels. Very simple fixed tax regimes not requiring any book...


    Directory of Open Access Journals (Sweden)

    Melisa Campana-Alabarce


    Full Text Available This article provides a characterization of Latin American and Caribbean Welfare regimes in historiographical perspective. Firstly, it makes a review of the emergence conditions of Welfare States in Western Europe and its core features, with particular emphasis on its role as a method to regulate inequalities in industrial capitalism. Dialoguing with it, then stops in the specific configurations that welfare regimes have taken in Latin America during the course of the twentieth century. Finally, it provides a map of its contemporary features and the major challenges that the States of the region face in his capacity as right guarantors for the future.

  14. Economic performance and North Korean regime legitimacy


    Moore, Patrick J.


    Approved for public release; distribution is unlimited This thesis examines the sources of legitimacy for the North Korean regime in an effort to explain what role, if any, economic performance has played in keeping the Kim family in power. This thesis provides a historical look at the development of the North Korean regime from the beginning under Kim Il-sung to the current generation of rule under Kim Jong-un. The core argument of the thesis is broken into two major time periods, with th...

  15. Degraded Confinement in Tokamak Experiments

    NARCIS (Netherlands)

    Schüller, F. C.


    After a review on the state of tokamak transport theory, the methodology to derive experimental results will be described. Examples of confinement in ohmic plasmas and the deterioration with additional heating will be given. Some examples of improved confinement modes will be discussed. Fluctuation

  16. High beta and confinement studies on TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Navratil, G.A.; Bhattacharjee, A.; Iacono, R.; Mauel, M.E.; Sabbagh, S.A. (Columbia Univ., New York, NY (United States)); Kesner, J. (Massachusetts Inst. of Tech., Cambridge, MA (United States))


    A new regime of high poloidal beta operation in TFTR was developed in the course of the first two years of this project (9/25/89 to 9/24/91). Our proposal to continue this successful collaboration between Columbia University and the Massachusetts Institute of Technology with the Princeton Plasma Physics Laboratory for a three year period (9/25/91 to 9/24/94) to continue to investigate improved confinement and tokamak performance in high poloidal beta plasmas in TFTR through the DT phase of operation was approved by the DOE and this is a report of our progress during the first 9 month budget period of the three year grant (9/25/91 to 6/24/92). During the approved three year project period we plan to (1) extend and apply the low current, high QDD discharges to the operation of TFTR using Deuterium and Tritium plasma; (2) continue the analysis and plan experiments on high poloidal beta phenomena in TFTR including: stability properties, enhanced global confinement, local transport, bootstrap current, and divertor formation; (3) plan and carry out experiments on TFTR which attempt to elevate the central q to values > 2 where entry to the second stability regime is predicted to occur; and (4) collaborate on high beta experiments using bean-shaped plasmas with a stabilizing conducting shell in PBX-M. In the seven month period covered by this report we have made progress in each of these four areas through the submission of 4 TFTR Experimental Proposals and the partial execution of 3 of these using a total of 4.5 run days during the August 1991 to February 1992 run.

  17. Gravitationally confined relativistic neutrinos (United States)

    Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.


    Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.

  18. Inertial confinement fusion

    Energy Technology Data Exchange (ETDEWEB)

    Powers, L.; Condouris, R.; Kotowski, M.; Murphy, P.W. (eds.)


    This issue of the ICF Quarterly contains seven articles that describe recent progress in Lawrence Livermore National Laboratory's ICF program. The Department of Energy recently initiated an effort to design a 1--2 MJ glass laser, the proposed National Ignition Facility (NIF). These articles span various aspects of a program which is aimed at moving forward toward such a facility by continuing to use the Nova laser to gain understanding of NIF-relevant target physics, by developing concepts for an NIF laser driver, and by envisioning a variety of applications for larger ICF facilities. This report discusses research on the following topics: Stimulated Rotational Raman Scattering in Nitrogen; A Maxwell Equation Solver in LASNEX for the Simulation of Moderately Intense Ultrashort Pulse Experiments; Measurements of Radial Heat-Wave Propagation in Laser-Produced Plasmas; Laser-Seeded Modulation Growth on Directly Driven Foils; Stimulated Raman Scattering in Large-Aperture, High-Fluence Frequency-Conversion Crystals; Fission Product Hazard Reduction Using Inertial Fusion Energy; Use of Inertial Confinement Fusion for Nuclear Weapons Effects Simulations.

  19. A new quasi-stationary, very high density plasma regime on the W7-AS stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Jaenicke, R; Baeumel, S; Baldzuhn, J; Brakel, R; Burhenn, R; Ehmler, H; Endler, M; Erckmann, V; Feng, Y; Gadelmeier, F; Geiger, J; Giannone, L; Grigull, P; Hartfuss, H J; Hartmann, D; Hildebrandt, D; Hirsch, M; Holzhauer, E; Kick, M; Kisslinger, J; Klinger, T; Klose, S; Knauer, J; Koenig, R; Kuehner, G; Laqua, H; Maassberg, H; McCormick, K; Narayanan, R; Niedermeyer, H; Pasch, E; Ruhs, N; Rust, N; Saffert, J; Sardei, F; Schneider, F; Schubert, M; Speth, E; Wagner, F; Weller, A; Wenzel, U; Werner, A; Wuersching, E [Max-Planck Institut fuer Plasmaphysik, EURATOM-Association, D-85748 Garching (Germany)


    Stellarators have the intrinsic property of steady state operation. However, on present-day stellarators the pulse length is usually not only limited due to technical reasons, but also by physical problems. Lack of density control and a subsequent radiation collapse terminate the discharges quite often at high densities. To improve the control of the plasma-wall interaction, the island divertor concept was developed for optimized stellarators. To test this divertor concept on W7-AS, all limiters were removed and replaced by ten divertor modules. In subsequent divertor experiments a promising new plasma operational regime has been discovered which is termed 'high density H-mode' (HDH-mode). During the transition into that regime a clear reduction of ELM-like events and turbulent fluctuations is observed. The HDH-mode combines good energy confinement with very low impurity confinement resulting in low core radiation, but high edge-localized radiation. Consequently, stationary discharges at densities of typically 2x10{sup 20} m{sup -3} can be performed within the accessible pulse length of about 1 s. At densities above 3x10{sup 20} m{sup -3} a controlled transition from attached to partially detached plasmas is observed. The still edge-localized radiation reaches 90% of the heating power so that the power load onto the divertor target plates is further reduced. At a lower toroidal field of 0.9 T average {beta}-values could be raised from earlier 2% to more than 3% in magnetic field configurations with rather smooth flux surfaces at the plasma boundary. The recently obtained results render excellent prospects for W7-X, the larger superconducting successor experiment of W7-AS.

  20. Formation and Collapse of Quiescent Cloud Cores Induced by Dynamic Compressions (United States)

    Gómez, Gilberto C.; Vázquez-Semadeni, Enrique; Shadmehri, Mohsen; Ballesteros-Paredes, Javier


    We present numerical hydrodynamic simulations of the formation, evolution, and gravitational collapse of isothermal molecular cloud cores in spherical geometry. A compressive wave is set up in a constant sub-Jeans density distribution of radius r=1 pc. As the wave travels through the simulation grid, a shock-bounded spherical shell is formed. The inner shock of this shell reaches and bounces off the center, leaving behind a central core with an initially almost uniform density distribution, surrounded by an envelope consisting of the material in the shock-bounded shell, which at late times develops a logarithmic slope close to -2, even in noncollapsing cases. The central core and the envelope are separated by a mild shock. The central core grows to sizes of ~0.1 pc and resembles a Bonnor-Ebert (BE) sphere, although it has significant dynamical differences: its self-gravity is initially negligible, and it is confined by the ram pressure of the infalling material, thus growing continuously in mass and size. With the appropriate parameters, the core mass eventually reaches an effective Jeans mass, at which time the core begins to collapse. Thus, the core evolves from a stable regime to an unstable one, implying the existence of a time delay between the appearance of the core and the onset of its collapse, but due to its growth in mass, rather than to the dissipation of its internal turbulence, as is often believed. These results suggest that prestellar cores may approximate BE structures, which are, however, of variable mass and may or may not experience gravitational collapse, in qualitative agreement with the large observed frequency of cores with BE-like profiles.

  1. Arctic circulation regimes. (United States)

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L


    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. © 2015 The Authors.


    Directory of Open Access Journals (Sweden)

    Gavril PANDI


    Full Text Available The influenced flow regimes. The presence and activities ofhumanity influences the uniform environmental system, and in this context, therivers water resources. In concordance with this, the natural runoff regime suffersbigger and deeper changes. The nature of these changes depending on the type anddegree of water uses. The multitude of the use cause different types of influence,whit different quantitative aspects. In the same time, the influences havequalitative connotations, too, regarding to the modifications of the yearly watervolume runoff. So the natural runoff regime is modified. After analyzing thedistribution laws of the monthly runoff, there have been differenced four types ofinfluenced runoff regimes. In the excess type the influenced runoff is bigger thanthe natural, continuously in the whole year. The deficient type is characterized byinverse rapports like the first type, in the whole year. In the sinusoidal type, theinfluenced runoff is smaller than the natural in the period when the water isretained in the lake reservoirs, and in the depletion period the situation inverts. Atthe irregular type the ratio between influenced and natural runoff is changeable ina random meaner monthly. The recognition of the influenced regime and the gradeof influence are necessary in the evaluation and analysis of the usable hydrologicalriver resources, in the flood defence activities, in the complex scheme of thehydrographic basins, in the environment design and so on.

  3. Understanding quantum confinement in nanowires: basics, applications and possible laws. (United States)

    Mohammad, S Noor


    A comprehensive investigation of quantum confinement in nanowires has been carried out. Though applied to silicon nanowires (SiNWs), it is general and applicable to all nanowires. Fundamentals and applications of quantum confinement in nanowires and possible laws obeyed by these nanowires, have been investigated. These laws may serve as backbones of nanowire science and technology. The relationship between energy band gap and nanowire diameter has been studied. This relationship appears to be universal. A thorough review indicates that the first principles results for quantum confinement vary widely. The possible cause of this variation has been examined. Surface passivation and surface reconstruction of nanowires have been elucidated. It has been found that quantum confinement owes its origin to surface strain resulting from surface passivation and surface reconstruction and hence thin nanowires may actually be crystalline-core/amorphous-shell (c-Si/a-Si) nanowires. Experimental data available in the literature corroborate with the suggestion. The study also reveals an intrinsic relationship between quantum confinement and the surface amorphicity of nanowires. It demonstrates that surface amorphicity may be an important tool to investigate the electronic, optoelectronic and sensorial properties of quantum-confined nanowires.

  4. Issues in tokamak/stellarator transport and confinement enhancement mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, F.W.


    At present, the mechanism for anomalous energy transport in low-{beta} toroidal plasmas -- tokamaks and stellarators -- remains unclear, although transport by turbulent E {times} B velocities associated with nonlinear, fine-scale microinstabilities is a leading candidate. This article discusses basic theoretical concepts of various transport and confinement enhancement mechanisms as well as experimental ramifications which would enable one to distinguish among them and hence identify a dominant transport mechanism. While many of the predictions of fine-scale turbulence are born out by experiment, notable contradictions exist. Projections of ignition margin rest both on the scaling properties of the confinement mechanism and on the criteria for entering enhanced confinement regimes. At present, the greatest uncertainties lie with the basis for scaling confinement enhancement criteria. A series of questions, to be answered by new experimental/theoretical work, is posed to resolve these outstanding contradictions (or refute the fine-scale turbulence model) and to establish confinement enhancement criteria. 73 refs., 4 figs., 5 tabs.


    Directory of Open Access Journals (Sweden)

    Javad Khazaei


    Full Text Available Helical piles are environmentally friendly and economical deep foundations that, due to environmental considerations, are excellent additions to a variety of deep foundation alternatives available to the practitioner. Helical piles performance depends on soil properties, the pile geometry and soil-pile interaction. Helical piles can be a proper alternative in sensitive environmental sites if their bearing capacity is sufficient to support applied loads. The failure capacity of helical piles in this study was measured via an experimental research program that was carried out by Frustum Confining Vessel (FCV. FCV is a frustum chamber by approximately linear increase in vertical and lateral stresses along depth from top to bottom. Due to special geometry and applied bottom pressure, this apparatus is a proper choice to test small model piles which can simulate field stress conditions. Small scale helical piles are made with either single helix or more helixes and installed in fine grained sand with three various densities. Axial loading tests including compression and tension tests were performed to achieve pile ultimate capacity. The results indicate the helical piles behavior depends essentially on pile geometric characteristics, i.e. helix configuration and soil properties. According to the achievements, axial uplift capacity of helical model piles is about equal to usual steel model piles that have the helixes diameter. Helical pile compression bearing capacity is too sufficient to act as a medium pile, thus it can be substituted other piles in special geoenvironmental conditions. The bearing capacity also depends on spacing ratio, S/D, and helixes diameter.

  6. Effect of shear in the radial electric field on confinement in JET

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, D.P.; Balet, B.; Deliyanakis, N.; Cordey, J.G.; Stubberfield, P.M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking


    The role of the radial electric field during enhanced confinement of JET discharges is studied. Results from two series of experiments are presented: beam dominated with the addition of a small amount of ICRH, and ICRH dominated discharges, showing that for high performance ICRH heated discharges which obtain the high confinement regime, there is evidence against the E x B flow stabilisation. 4 refs., 4 figs.

  7. Proteomics Core (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  8. Confining Strings with Topological Term

    CERN Document Server

    Diamantini, M Cristina; Trugenberger, Carlo Andrea


    We consider several aspects of `confining strings', recently proposed to describe the confining phase of gauge field theories. We perform the exact duality transformation that leads to the confining string action and show that it reduces to the Polyakov action in the semiclassical approximation. In 4D we introduce a `$\\theta$-term' and compute the low-energy effective action for the confining string in a derivative expansion. We find that the coefficient of the extrinsic curvature (stiffness) is negative, confirming previous proposals. In the absence of a $\\theta$-term, the effective string action is only a cut-off theory for finite values of the coupling e, whereas for generic values of $\\theta$, the action can be renormalized and to leading order we obtain the Nambu-Goto action plus a topological `spin' term that could stabilize the system.

  9. Alternative approaches to plasma confinement (United States)

    Roth, J. R.


    The paper discusses 20 plasma confinement schemes each representing an alternative to the tokamak fusion reactor. Attention is given to: (1) tokamak-like devices (TORMAC, Topolotron, and the Extrap concept), (2) stellarator-like devices (Torsatron and twisted-coil stellarators), (3) mirror machines (Astron and reversed-field devices, the 2XII B experiment, laser-heated solenoids, the LITE experiment, the Kaktus-Surmac concept), (4) bumpy tori (hot electron bumpy torus, toroidal minimum-B configurations), (5) electrostatically assisted confinement (electrostatically stuffed cusps and mirrors, electrostatically assisted toroidal confinement), (6) the Migma concept, and (7) wall-confined plasmas. The plasma parameters of the devices are presented and the advantages and disadvantages of each are listed.

  10. Supply regimes in fisheries

    DEFF Research Database (Denmark)

    Nielsen, Max


    Supply in fisheries is traditionally known for its backward bending nature, owing to externalities in production. Such a supply regime, however, exist only for pure open access fisheries. Since most fisheries worldwide are neither pure open access, nor optimally managed, rather between the extrem...

  11. Validation of a coupled core-transport, pedestal-structure, current-profile and equilibrium model (United States)

    Meneghini, O.


    The first workflow capable of predicting the self-consistent solution to the coupled core-transport, pedestal structure, and equilibrium problems from first-principles and its experimental tests are presented. Validation with DIII-D discharges in high confinement regimes shows that the workflow is capable of robustly predicting the kinetic profiles from on axis to the separatrix and matching the experimental measurements to within their uncertainty, with no prior knowledge of the pedestal height nor of any measurement of the temperature or pressure. Self-consistent coupling has proven to be essential to match the experimental results, and capture the non-linear physics that governs the core and pedestal solutions. In particular, clear stabilization of the pedestal peeling ballooning instabilities by the global Shafranov shift and destabilization by additional edge bootstrap current, and subsequent effect on the core plasma profiles, have been clearly observed and documented. In our model, self-consistency is achieved by iterating between the TGYRO core transport solver (with NEO and TGLF for neoclassical and turbulent flux), and the pedestal structure predicted by the EPED model. A self-consistent equilibrium is calculated by EFIT, while the ONETWO transport package evolves the current profile and calculates the particle and energy sources. The capabilities of such workflow are shown to be critical for the design of future experiments such as ITER and FNSF, which operate in a regime where the equilibrium, the pedestal, and the core transport problems are strongly coupled, and for which none of these quantities can be assumed to be known. Self-consistent core-pedestal predictions for ITER, as well as initial optimizations, will be presented. Supported by the US Department of Energy under DE-FC02-04ER54698, DE-SC0012652.

  12. Reatividade animal Confinement reactivity

    Directory of Open Access Journals (Sweden)

    Walsiara Estanislau Maffei


    Full Text Available A reatividade é definida como a reação do animal quando contido num ambiente de contenção móvel. Ela é quantificada por meio do teste de reatividade animal em ambiente de contenção móvel - REATEST®. Este teste consiste num dispositivo eletrônico acoplado à balança e num software específico. O dispositivo capta a movimentação que o animal provoca na balança, durante 20 segundos e a envia para o software que a processa determinando a reatividade do animal numa escala contínua de pontos. Pontuações maiores são de animais mais reativos (mais agressivo. A reatividade foi criada com os objetivos de solucionar os problemas até então existentes na seleção para temperamento e de permitir estimação de parâmetros genéticos mais confiáveis. Ela é uma característica objetiva que tem grande variabilidade fenotípica e é de quantificação rápida, fácil e segura, além de poder ser quantificada em qualquer tipo de balança, o que permite maior aplicabilidade. Ela não interfere nas práticas de manejo das fazendas porque é quantificada no momento da pesagem dos animais. Sua herdabilidade na raça Nelore é de 0,39 ao ano e 0,23 ao sobreano e suas correlações genéticas com ganho de peso diário são de -0,28 do nascimento até desmama e de -0,49 do desmame até ano. Já suas correlações genéticas com desenvolvimento do perímetro escrotal do ano ao sobreano variam de -0,25 e -0,41.The confinement reactivity (CR has been used as a measure of temperament in Brazil and it is defined as the animal reaction when contained in the scale. It is quantified through the animal reactivity test - REATEST®. This test consists of an electronic device coupled to the scale and of specific software. The device captures the movement that the animal provokes in the scale, during 20 seconds and sends it for the software that processes this movement and determines the animal CR in a continuous scale of points. Higher punctuations belong to

  13. Statistical Contact Model for Confined Molecules (United States)

    Santamaria, Ruben; de la Paz, Antonio Alvarez; Roskop, Luke; Adamowicz, Ludwik


    A theory that describes in a realistic form a system of atoms under the effects of temperature and confinement is presented. The theory departs from a Lagrangian of the Zwanzig type and contains the main ingredients for describing a system of atoms immersed in a heat bath that is also formed by atoms. The equations of motion are derived according to Lagrangian mechanics. The application of statistical mechanics to describe the bulk effects greatly reduces the complexity of the equations. The resultant equations of motion are of the Langevin type with the viscosity and the temperature of the heat reservoir able to influence the trajectories of the particles. The pressure effects are introduced mechanically by using a container with an atomic structure immersed in the heat bath. The relevant variables that determine the equation of state are included in the formulation. The theory is illustrated by the derivation of the equation of state for a system with 76 atoms confined inside of a 180-atom fullerene-like cage that is immersed in fluid forming the heat bath at a temperature of 350 K and with the friction coefficient of 3.0 {ps}^{-1}. The atoms are of the type believed to form the cores of the Uranus and Neptune planets. The dynamic and the static pressures of the confined system are varied in the 3-5 KBar and 2-30 MBar ranges, respectively. The formulation can be equally used to analyze chemical reactions under specific conditions of pressure and temperature, determine the structure of clusters with their corresponding equation of state, the conditions for hydrogen storage, etc. The theory is consistent with the principles of thermodynamics and it is intrinsically ergodic, of general use, and the first of this kind.

  14. PREFACE: Water in confined geometries (United States)

    Rovere, Mauro


    The study of water confined in complex systems in solid or gel phases and/or in contact with macromolecules is relevant to many important processes ranging from industrial applications such as catalysis and soil chemistry, to biological processes such as protein folding or ionic transport in membranes. Thermodynamics, phase behaviour and the molecular mobility of water have been observed to change upon confinement depending on the properties of the substrate. In particular, polar substrates perturb the hydrogen bond network of water, inducing large changes in the properties upon freezing. Understanding how the connected random hydrogen bond network of bulk water is modified when water is confined in small cavities inside a substrate material is very important for studies of stability and the enzymatic activity of proteins, oil recovery or heterogeneous catalysis, where water-substrate interactions play a fundamental role. The modifications of the short-range order in the liquid depend on the nature of the water-substrate interaction, hydrophilic or hydrophobic, as well as on its spatial range and on the geometry of the substrate. Despite extensive study, both experimentally and by computer simulation, there remain a number of open problems. In the many experimental studies of confined water, those performed on water in Vycor are of particular interest for computer simulation and theoretical studies since Vycor is a porous silica glass characterized by a quite sharp distribution of pore sizes and a strong capability to absorb water. It can be considered as a good candidate for studying the general behaviour of water in hydrophilic nanopores. But there there have been a number of studies of water confined in more complex substrates, where the interpretation of experiments and computer simulation is more difficult, such as in zeolites or in aerogels or in contact with membranes. Of the many problems to consider we can mention the study of supercooled water. It is

  15. Changes in transport and confinement in the EXTRAP-T2 reversed field pinch (United States)

    Sallander, E.; Sallander, J.; Hedqvist, A.


    At the EXTRAP-T2 reversed field pinch a non-intrusive approach has been undertaken to monitor transport driven by magnetic fluctuations. Correlations are presented between fluctuations observed in the core and at the edge of the plasma. The fluctuations are characterized and their effect on the confinement of core electron energy is estimated.

  16. Intrinsic Flow and Momentum Transport during Improved Confinement in MST (United States)

    Craig, D.; Tan, E.; Schott, B.; Anderson, J. K.; Boguski, J.; Nornberg, M. D.; Xing, Z. A.


    Progress in absolute wavelength calibration of the Charge Exchange Recombination Spectroscopy (CHERS) system on MST has enabled new observations and analysis of intrinsic flow and momentum transport. Localized toroidal and poloidal flow measurements with systematic accuracy of +/- 3 km/s have been obtained during improved confinement Pulsed Parallel Current Drive (PPCD) plasmas at high plasma current (400-500 kA). The magnetic activity prior to and during the transition to improved confinement tends to increase the flow and sets the initial condition for the momentum profile evolution during improved confinement where intrinsic flow drive appears to weaken. Inboard flows change in time during PPCD, consistent with changes in the core-resonant m =1, n =6 tearing mode phase velocity. Outboard flows near the magnetic axis are time-independent, resulting in the development of a strongly sheared toroidal flow in the core and asymmetry in the poloidal flow profile. The deceleration of the n =6 mode during the period of improved confinement correlates well with the n =6 mode amplitude and is roughly consistent with the expected torque from eddy currents in the conducting shell. The level of Dα emission and secondary mode amplitudes (n =7-10) do not correlate with the mode deceleration suggesting that the momentum loss from charge exchange with neutrals and diffusion due to residual magnetic stochasticity are not significant in PPCD. This work has been supported by the U.S.D.O.E.

  17. Novel High Negative Chromatic Dispersion Photonic Crystal Fiber with Low Confinement Loss

    Directory of Open Access Journals (Sweden)

    OUADAH Mohammed Chamse Eddine


    Full Text Available In this paper, we propose a novel dual core concentric photonic crystal fiber with high negative chromatic dispersion and low confinement loss. Finite element method with perfectly matched layers (PMLS is used to investigate the guiding properties. In order to achieve a high negative chromatic dispersion, small air holes are added in the inner core as well as the liquid filling the outer core. The numerical results show a negative dispersion coefficient and confinement loss of -78010ps/nm/km, 0.05dB/km respectively at λ=155μm, which make the proposed design an excellent device in high transmission system for dispersion compensation.

  18. East Asian welfare regime

    DEFF Research Database (Denmark)

    Abrahamson, Peter


    The paper asks if East Asian welfare regimes are still productivist and Confucian? And, have they developed public care policies? The literature is split on the first question but (mostly) confirmative on the second. Care has to a large, but insufficient extent, been rolled out in the region. Pol...... focusing on outcomes or causal links tend to suggest that legacies prevail, but there is (nearly) consensus that Confucianism exercises great influence in the whole region....

  19. Correlation of microfractures with P-wave velocities and strain in cored rock samples from the Yutsubo geothermal well deformed under confining pressures; Fuatsuka no P ha sokudo henka to hizumi henka kara suiteisareta Yutsubo chinetsusei core shiryo no wareme no seijo

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Z. [Kiso-Jiban Consultants Co. Ltd., Tokyo (Japan); Nishizawa, O.; Kuwahara, Y. [Geological Survey of Japan, Tsukuba (Japan); Suzuki, S. [Okayama University, Okayama (Japan). Faculty of Science


    With an objective to identify underground rock properties, measurements were made on strains and elastic wave velocities of boring cores under hydrostatic pressure in a geothermal experimental field. Microstructures of rock samples were also observed by using a microscope. Four samples were collected from two test wells each at two locations of different depths. The following findings were obtained: a phenomenon exists that ratio of increase in the strain changes at certain pressure as a border in a high- pressure region (strain inflection point). Pressure at the strain inflection point was as relatively low as 40 MPa, no marks of void fracture were observed, and elastic deformation of particles was verified. This phenomenon varies with rock types. Samples taken from great depths presented cracks. Although hysteresis appears in mineral particles plastically deformed, cracks are filled with calcite, hence no variation corresponding to non-uniformity appears in the P-wave velocity. The reason for the P-wave velocity to become lower in a load removing process is because cracks have developed from cracks that have existed previously. Difference may be seen in anisotropy patterns of strains and P-wave velocities among samples, whose cause may be other than the cracks. 15 refs., 24 figs.

  20. Sandpile model with tokamaklike enhanced confinement phenomenology. (United States)

    Chapman, S C; Dendy, R O; Hnat, B


    Confinement phenomenology characteristic of magnetically confined plasmas emerges naturally from a simple sandpile algorithm when the parameter controlling redistribution scale length is varied. Close analogs are found for enhanced confinement, edge pedestals, and edge localized modes (ELMs), and for the qualitative correlations between them. These results suggest that tokamak observations of avalanching transport are deeply linked to the existence of enhanced confinement and ELMs.

  1. Phenomenological sizes of confinement regions in baryons

    Energy Technology Data Exchange (ETDEWEB)

    Brown, G.E.; Klimt, S.; Weise, W.; Rho, M.


    Standard order of magnitude estimates from QCD indicate that the radius of the quark-gluon core in the nucleon is ..lambda../sup -1//sub QCD/ > or approx. 1 fm. However, in work with the chiral bag model, we have found that the effective confinement size for low energy reactions can be as small as approx. = 1/2 fm or smaller. This shrinking of the effective confinement size has been attributed to the pressure of the pion cloud surrounding the quark core. The concept of confinement size is evidently subtle in light-quark systems, due to the chiral vacuum structure. This is indicated by the 'Cheshire Cat' phenomenon, in which physical observables tend to be insensitive to the bag radius R. We suggest that when strange quarks are present, a qualitative change occurs in the Cheshire Cat picture; in particular, we propose that strangeness provides an obstruction to this picture. We present a phenomenological indication that when strange quarks are present, the bag radius R is frozen at a value substantially larger than 0.5 fm by as much as a factor of two. Roughly speaking, the Cheshire Cat picture emerges from a near cancellation between repulsive quark kinetic and attractive pion-cloud energies in the case of the nucleon. In the ..lambda.. and ..sigma.. particles, however, replacement of one up or down quark by a strange quark removes part of the attraction from the coupling of the quarks to the pion cloud. This upsets the balance needed for the Cheshire Cat phenomenon and makes larger strange baryons more favorable energetically than the 0.5 fm ones appropriate for pure u- and d-systems. We find that magnetic moments of strange baryons favor a bag radius R approx. = 1.1 fm. We find that the excited states of the ..lambda..-hyperons favor similarly large bag radii. Somewhat less convincingly, due to perturbative effects - the bag radius appropriate to the lies intermediate between that of the nucleon and of the stran

  2. Subdiffraction confinement in dielectric waveguide with extreme anisotropy (United States)

    Bian, Tingting


    All-dielectric slab waveguide filling the core with metamaterials of extreme anisotropy realizes the light transport being confined in a subdiffraction region with substantial energy concentration. The extreme anisotropy makes the evanescent waves in the claddings decay faster and the guided mode tightly localized in the core. Furthermore, the cutoff width can be decoupled from the group velocity of the mode, it can reach zero in the limit of extreme anisotropy but still sustain considerable group velocity. We analyze technically realizable cases and conclude that our work can contribute to improvements of various electromagnetic devices, from visible to microwave frequency regions.

  3. Air- and water-core integrated optical waveguides

    NARCIS (Netherlands)

    Uranus, H.P.; Hoekstra, Hugo; van Groesen, Embrecht W.C.


    Hollow-core integrated optical waveguides enable quasi-confinement of light into the hollow-core, hence offer intense interaction between light and gas or liquid filled into the core on one hand and prospective for integration of various components (not only photonic components, but also


    Energy Technology Data Exchange (ETDEWEB)



    This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed

  5. Knotted DNA in Nanofluidic Confinement (United States)

    Klotz, Alexander; Doyle, Patrick

    The behavior of topologically simple semiflexible polymers such as DNA has become well-understood in the last several years. Recently, several computational analyses have predicted that certain topological features of a polymer, such as the average size of pseudo-knots and the probability of knot formation, are enhanced by confinement. Here, we extend recent work on the stretching of knotted DNA and examine diffusion, relaxation, and chain statistics of topologically complex linear DNA molecules. Topological phenomena are studied both in the bulk and under nanofluidic confinement to examine the interplay between knotting and confinement in semiflexible polymers, as well as to provide a controlled experimental interrogation of the knotted region of the polymer.

  6. Pellet injection and confinement in the tore supra tokamak; Injection de glacons et confinement dans le tokamak tore supra

    Energy Technology Data Exchange (ETDEWEB)

    Maget, P


    Pellet injection in the centre of tokamak plasmas can lead to an improved confinement regime called PEP (Pellet Enhanced Performance). The present work is dedicated to the mechanisms involved in the PEP regimes obtained in the tokamak Tore Supra. A neoclassical approach of transport shows that it is the anomalous transport, due to plasma turbulence, that causes the enhanced confinement. A linear model describing electrostatic instabilities has been developed in order to study the roles of density profile and current profile during the PEP, in the limit of large growth rates. The effect ofradial shear in flows is taken into account by removing the ExB shear flow rate from the linear growth rate, as suggested by non-linear numerical simulations of turbulence. A local transport coefficient is estimated from the knowledge of the linear growth rate and the mode width. We find that the peaked density profile in PEP regime lowers the diffusion coefficient, and that the velocity shear amplifies this effect. The evolution of the current profile is also stabilizing, but this parameter is not known with sufficient accuracy, so that its role in Tore Supra PEP experiments remains uncertain. (author)

  7. Suppression of instabilities in multiphase flow by geometric confinement. (United States)

    Humphry, Katherine J; Ajdari, Armand; Fernández-Nieves, Alberto; Stone, Howard A; Weitz, David A


    We investigate the effect of confinement on drop formation in microfluidic devices. The presence or absence of drop formation is studied for two immiscible coflowing liquids in a microfluidic channel, where the channel width is considerably larger than the channel height. We show that stability of the inner fluid thread depends on the channel geometry: when the width of the inner fluid is comparable to or larger than the channel height, hydrodynamic instabilities are suppressed, and a stable jet that does not break into drops results; otherwise, the inner fluid breaks into drops, in either a dripping or jetting regime. We present a model that accounts for the data and experimentally exploit this effect of geometric confinement to induce the breakup of a jet at a spatially defined location.

  8. Calculation of confined swirling jets (United States)

    Chen, C. P.


    Computations of a confined coaxial swirling jet are carried out using a standard two-equation (k-epsilon) model and two modifications of this model based on Richardson-number corrections of the length-scale (epsilon) governing equation. To avoid any uncertainty involved in the setting up of inlet boundary conditions, actual measurements are used at the inlet plane of this calculation domain. The results of the numerical investigation indicate that the k-epsilon model is inadequate for the predictions of confined swirling flows. Although marginal improvement of the flow predictions can be achieved by these two corrections, neither can be judged satisfactory.


    NARCIS (Netherlands)



    The average size and shape of a polymer coil confined in a slit between two parallel plates depends on the distance L between the plates. On the basis of numerical results, four different regimes can be distinguished. For large values of L the coil is essentially unconfined. For intermediate values

  10. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders


    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  11. Regimes of Autonomy

    NARCIS (Netherlands)

    Anderson, Joel


    Like being able to drive a car, being autonomous is a socially attributed, claimed, and contested status. Normative debates about criteria for autonomy (and what autonomy entitles one to) are best understood, not as debates about what autonomy, at core, really is, but rather as debates about the

  12. Confinement Studies in High Temperature Spheromak Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hill, D N; Mclean, H S; Wood, R D; Casper, T A; Cohen, B I; Hooper, E B; LoDestro, L L; Pearlstein, L D; Romero-Talamas, C


    Recent results from the SSPX spheromak experiment demonstrate the potential for obtaining good energy confinement (Te > 350eV and radial electron thermal diffusivity comparable to tokamak L-mode values) in a completely self-organized toroidal plasma. A strong decrease in thermal conductivity with temperature is observed and at the highest temperatures, transport is well below that expected from the Rechester-Rosenbluth model. Addition of a new capacitor bank has produced 60% higher magnetic fields and almost tripled the pulse length to 11ms. For plasmas with T{sub e} > 300eV, it becomes feasible to use modest (1.8MW) neutral beam injection (NBI) heating to significantly change the power balance in the core plasma, making it an effective tool for improving transport analysis. We are now developing detailed designs for adding NBI to SSPX and have developed a new module for the CORSICA transport code to compute the correct fast-ion orbits in SSPX so that we can simulate the effect of adding NBI; initial results predict that such heating can raise the electron temperature and total plasma pressure in the core by a factor of two.

  13. Confinement and stability of VH-mode discharges in the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, T.S.; Osborne, T.H.; Burrell, K.H.; Carlstrom, T.N.; Chan, V.S.; Chu, M.S.; DeBoo, J.C.; Doyle, E.J.; Greenfield, C.M.; Groebner, R.J.; Hsieh, C.L.; Jackson, G.L.; James, R.; Lao, L.L.; Lazarus, E.A.; Lippman, S.I.; Petrie, T.W.; Rettig, C.L.; St. John, H.; Schissel, D.P.; Stambaugh, R.D.; Strait, E.J.; Turnbull, A.D.; West, W.P.; Winter, J.; Wroblewski, D.


    A regime of very high confinement (VH-mode) has been observed in neutral beam-heated deuterium discharges in the DIII-D tokamak with thermal energy confinement times up to [approx]3.6 times that predicted by the ITER-89P L-mode scaling and 2 times that predicted by ELM-free H-mode thermal confinement scalings. This high confinement has led to increased plasma performance, n[sub D] (0)T[sub i](0)[tau][sub E] = 2 [times] 10[sup 20] m[sup [minus]3] keV sec with I[sub p] = 1.6 MA, B[sub T] = 2.1 T, Z[sub eff] [le] 2. Detailed transport analysis shows a correspondence between the large decrease in thermal diffusivity in the region 0.75 [le] [rho] [le] 0.9 and the development of a strong shear in the radial electric field in the same region. This suggests that stabilization of turbulence by sheared E [times] B flow is responsible for the improved confinement in VH-mode. A substantial fraction of the edge plasma entering the second regime of stability may also contribute to the increase in confinement. The duration of the VH-mode phase has been lengthened by feedback controlling the input power to limit plasma beta.

  14. Confinement and stability of VH-mode discharges in the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, T.S.; Osborne, T.H.; Burrell, K.H.; Carlstrom, T.N.; Chan, V.S.; Chu, M.S.; DeBoo, J.C.; Doyle, E.J.; Greenfield, C.M.; Groebner, R.J.; Hsieh, C.L.; Jackson, G.L.; James, R.; Lao, L.L.; Lazarus, E.A.; Lippman, S.I.; Petrie, T.W.; Rettig, C.L.; St. John, H.; Schissel, D.P.; Stambaugh, R.D.; Strait, E.J.; Turnbull, A.D.; West, W.P.; Winter, J.; Wroblewski, D.


    A regime of very high confinement (VH-mode) has been observed in neutral beam-heated deuterium discharges in the DIII-D tokamak with thermal energy confinement times up to {approx}3.6 times that predicted by the ITER-89P L-mode scaling and 2 times that predicted by ELM-free H-mode thermal confinement scalings. This high confinement has led to increased plasma performance, n{sub D} (0)T{sub i}(0){tau}{sub E} = 2 {times} 10{sup 20} m{sup {minus}3} keV sec with I{sub p} = 1.6 MA, B{sub T} = 2.1 T, Z{sub eff} {le} 2. Detailed transport analysis shows a correspondence between the large decrease in thermal diffusivity in the region 0.75 {le} {rho} {le} 0.9 and the development of a strong shear in the radial electric field in the same region. This suggests that stabilization of turbulence by sheared E {times} B flow is responsible for the improved confinement in VH-mode. A substantial fraction of the edge plasma entering the second regime of stability may also contribute to the increase in confinement. The duration of the VH-mode phase has been lengthened by feedback controlling the input power to limit plasma beta.

  15. Turbulent jet in confined counterflow

    Indian Academy of Sciences (India)

    The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct limit of ...

  16. Turbulent jet in confined counterflow

    Indian Academy of Sciences (India)

    Abstract. The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct ...

  17. Effective viscosity of confined hydrocarbons

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.


    We present molecular dynamics friction calculations for confined hydrocarbon films with molecular lengths from 20 to 1400 carbon atoms. We find that the logarithm of the effective viscosity ηeff for nanometer-thin films depends linearly on the logarithm of the shear rate: log ηeff=C-nlog γ̇, where...

  18. Unstable vortices do not confine

    NARCIS (Netherlands)

    Achúcarro, A.; Roo, M. de; Huiszoon, L.; Landshoff, P.V.


    Recently, a geometric model for the confinement of magnetic charges in the context of type II string compactifications was constructed. This model assumes the existence of stable magnetic vortices with quantized flux in the low energy theory. However, quantization of flux alone does not imply that

  19. Two flavor QCD and Confinement

    DEFF Research Database (Denmark)

    D'Elia, M.; Di Giacomo, A.; Pica, Claudio


    We argue that the order of the chiral transition for N_f=2 is a sensitive probe of the QCD vacuum, in particular of the mechanism of color confinement. A strategy is developed to investigate the order of the transition by use of finite size scaling analysis. An in-depth numerical investigation...

  20. Thermalization in a holographic confining gauge theory

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Takaaki [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); Kiritsis, Elias [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); APC, University Paris Diderot, Sorbonne Paris Cité, UMR 7164 CNRS,10, rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Rosen, Christopher [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece)


    Time dependent perturbations of states in the holographic dual of a 3+1 dimensional confining theory are considered. The perturbations are induced by varying the coupling to the theory’s most relevant operator. The dual gravitational theory belongs to a class of Einstein-dilaton theories which exhibit a mass gap at zero temperature and a first order deconfining phase transition at finite temperature. The perturbation is realized in various thermal bulk solutions by specifying time dependent boundary conditions on the scalar, and we solve the fully backreacted Einstein-dilaton equations of motion subject to these boundary conditions. We compute the characteristic time scale of many thermalization processes, noting that in every case we examine, this time scale is determined by the imaginary part of the lowest lying quasi-normal mode of the final state black brane. We quantify the dependence of this final state on parameters of the quench, and construct a dynamical phase diagram. Further support for a universal scaling regime in the abrupt quench limit is provided.

  1. Confined nanoparticle measurement using Bessel Beam Microscopy (United States)

    Chakraborty, Chumki; Snoeyink, Craig


    With the advent of Lab-on-chip technologies, study of near surface phenomenon has gained a lot of importance due to their huge impact on bulk fluid properties. Such studies demand imaging techniques with utmost precision to capture the intricate details of the interface. But, resolution for most of the optical imaging systems is limited due to the light spreading effects of diffraction. This diffraction limited resolution, can be improved by the use of Bessel Beam microscopy. Bessel beam imaging technique when combined with a TIRF (Total Internal Reflection Fluorescence) system can be used for high resolution particle tracking experiments, to reveal detailed information about near surface particle positions and motions with their velocity profile and distribution. With the experimental set up combining these two powerful tools, we plan to present our particle tracking velocimetry results in the interface regime of confined nanoparticles in a binary fluid mixture. Such a study can contribute towards a better understanding of near surface fluid-particle interfaces.

  2. Extremes of 2d Coulomb gas: universal intermediate deviation regime (United States)

    Lacroix-A-Chez-Toine, Bertrand; Grabsch, Aurélien; Majumdar, Satya N.; Schehr, Grégory


    In this paper, we study the extreme statistics in the complex Ginibre ensemble of N × N random matrices with complex Gaussian entries, but with no other symmetries. All the N eigenvalues are complex random variables and their joint distribution can be interpreted as a 2d Coulomb gas with a logarithmic repulsion between any pair of particles and in presence of a confining harmonic potential v(r) \\propto r2 . We study the statistics of the eigenvalue with the largest modulus r\\max in the complex plane. The typical and large fluctuations of r\\max around its mean had been studied before, and they match smoothly to the right of the mean. However, it remained a puzzle to understand why the large and typical fluctuations to the left of the mean did not match. In this paper, we show that there is indeed an intermediate fluctuation regime that interpolates smoothly between the large and the typical fluctuations to the left of the mean. Moreover, we compute explicitly this ‘intermediate deviation function’ (IDF) and show that it is universal, i.e. independent of the confining potential v(r) as long as it is spherically symmetric and increases faster than \\ln r2 for large r with an unbounded support. If the confining potential v(r) has a finite support, i.e. becomes infinite beyond a finite radius, we show via explicit computation that the corresponding IDF is different. Interestingly, in the borderline case where the confining potential grows very slowly as v(r) ∼ \\ln r2 for r \\gg 1 with an unbounded support, the intermediate regime disappears and there is a smooth matching between the central part and the left large deviation regime.

  3. Exercise thermoregulation with bed rest, confinement, and immersion deconditioning. (United States)

    Greenleaf, J E


    Altered thermoregulation following exposure to prolonged (12-14 days) of bed rest and 6 hr of head-down thermoneutral water immersion in humans, and cage confinement (8 weeks) in male, mongrel dogs resulted in occasional increased core temperature (Tcore) at rest, but consistent "excessive" increase in Tcore during submaximal exercise. This excessive increase in Tcore in nonexercising and exercising subjects was independent of the mode (isometric or isotonic) of exercise training during bed rest, and was associated with the consistent hypovolemia in men but not in women taking estrogen supplementation (1.25 mg premarin/ day) which restored plasma volume during bed rest to ambulatory control levels. Post-bed rest exercise sweating (evaporative heat loss) was unchanged or higher than control levels; however, calculated tissue heat conductance was significantly lower in men, and forearm venoconstriction was greater (venous volume was reduced) in women during exercise after bed rest. Because sweating appeared proportional to the increased level of Tcore, these findings suggest that one major factor for the excessive hyperthermia is decreased core to periphery heat conduction. Exercising dogs respond like humans with excessive increase in both rectal (Tre) and exercising muscle temperatures (Tmu) after confinement and, after eight weeks of exercise training on a treadmill following confinement, they had an attenuated rate of increase of Tre even below ambulatory control levels. Intravenous infusion of glucose also attenuated not only the rise in Tre during exercise in normal dogs, but also the excessive rise in Tre and exercising Tmu after confinement. Oral glucose also appeared to reduce the rate of increase in excessive Tre in men after immersion deconditioning. There was a greater rate of rise in Tcore in two cosmonauts during supine submaximal exercise (65% VO2 max) on the fifth recovery day after the 115-day Mir 18 mission. Thus, the excessive rise in core

  4. Exercise thermoregulation with bed rest, confinement, and immersion deconditioning (United States)

    Greenleaf, J. E.


    Altered thermoregulation following exposure to prolonged (12-14 days) of bed rest and 6 hr of head-down thermoneutral water immersion in humans, and cage confinement (8 weeks) in male, mongrel dogs resulted in occasional increased core temperature (Tcore) at rest, but consistent "excessive" increase in Tcore during submaximal exercise. This excessive increase in Tcore in nonexercising and exercising subjects was independent of the mode (isometric or isotonic) of exercise training during bed rest, and was associated with the consistent hypovolemia in men but not in women taking estrogen supplementation (1.25 mg premarin/ day) which restored plasma volume during bed rest to ambulatory control levels. Post-bed rest exercise sweating (evaporative heat loss) was unchanged or higher than control levels; however, calculated tissue heat conductance was significantly lower in men, and forearm venoconstriction was greater (venous volume was reduced) in women during exercise after bed rest. Because sweating appeared proportional to the increased level of Tcore, these findings suggest that one major factor for the excessive hyperthermia is decreased core to periphery heat conduction. Exercising dogs respond like humans with excessive increase in both rectal (Tre) and exercising muscle temperatures (Tmu) after confinement and, after eight weeks of exercise training on a treadmill following confinement, they had an attenuated rate of increase of Tre even below ambulatory control levels. Intravenous infusion of glucose also attenuated not only the rise in Tre during exercise in normal dogs, but also the excessive rise in Tre and exercising Tmu after confinement. Oral glucose also appeared to reduce the rate of increase in excessive Tre in men after immersion deconditioning. There was a greater rate of rise in Tcore in two cosmonauts during supine submaximal exercise (65% VO2 max) on the fifth recovery day after the 115-day Mir 18 mission. Thus, the excessive rise in core

  5. A double-layer based model of ion confinement in electron cyclotron resonance ion source (United States)

    Mascali, D.; Neri, L.; Celona, L.; Castro, G.; Torrisi, G.; Gammino, S.; Sorbello, G.; Ciavola, G.


    The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this "barrier" confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

  6. A double-layer based model of ion confinement in electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Mascali, D., E-mail:; Neri, L.; Celona, L.; Castro, G.; Gammino, S.; Ciavola, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Torrisi, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile, Via Graziella, I-89100 Reggio Calabria (Italy); Sorbello, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica, Viale Andrea Doria 6, 95125 Catania (Italy)


    The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this “barrier” confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

  7. Fulde–Ferrell state in superconducting core/shell nanowires: role of the orbital effect (United States)

    Mika, Marek; Wójcik, Paweł


    The orbital effect on the Fulde–Ferrell (FF) phase is investigated in superconducting core/shell nanowires subjected to the axial magnetic field. Confinement in the radial direction results in quantization of the electron motion with energies determined by the radial j and orbital m quantum numbers. In the external magnetic field, the twofold degeneracy with respect to the orbital magnetic quantum number m is lifted which leads to the Fermi wave vector mismatch between the paired electrons, (k, j, m, \\uparrow) ≤ftrightarrow (-k, j, -m, \\downarrow) . This mismatch is transferred to the nonzero total momentum of the Cooper pairs, which results in a formation of the FF phase occurring sequentially with increasing magnetic field. By changing the nanowire radius R and the superconducting shell thickness d, we discuss the role of the orbital effect in the FF phase formation in both the nanowire-like (R/d \\ll 1 ) and nanofilm-like (R/d \\gg 1 ) regime. We have found that the irregular pattern of the FF phase which appears for the case of the nanowire-like regime, for the nanofilm-like geometry evolves towards the regular distribution in which the FF phase stability regions emerge periodically between the BCS states. The transition between these two different phase diagrams is explained as resulting from the orbital effect and the multigap character of superconductivity in the core/shell nanowires.

  8. Fulde-Ferrell state in superconducting core/shell nanowires: role of the orbital effect. (United States)

    Mika, Marek; Wojcik, Pawel


    The orbital effect on the Fulde-Ferrell (FF) phase is investigated in superconducting core/shell nanowires subjected to the axial magnetic field. The confinement in the radial direction results in the quantization of the electron motion with energies determined by the radial $j$ and orbital $m$ quantum numbers. In the external magnetic field the twofold degeneracy with respect to the orbital magnetic quantum number $m$ is lifted which leads to the Fermi wave vector mismatch between the paired electrons $(k, j,m,\\uparrow) \\leftrightarrow (-k, j,-m,\\downarrow)$. This mismatch is transfered to the nonzero total momentum of the Cooper pairs which results in the formation of FF phase occurring sequentially with increasing magnetic field. By changing the nanowire radius $R$ and the superconducting shell thickness $d$, we discuss the role of the orbital effect in the FF phase formation in both the nanowire-like ($R/d \\ll 1$) and nanofilm-like ($R/d \\gg 1$) regime. We have found that the irregular pattern of the FF phase, which appears for the case of the nanowire-like regime, evolves towards the regular distribution, in which the FF phase stability regions appear periodically between the BCS state, for the nanofilm-like geometry. The crossover between these two different phase diagrams is explained as resulting from the orbital effect and the multigap character of superconductivity in core/shell nanowires. © 2017 IOP Publishing Ltd.

  9. Characteristics of regulatory regimes

    Directory of Open Access Journals (Sweden)

    Noralv Veggeland


    Full Text Available The overarching theme of this paper is institutional analysis of basic characteristics of regulatory regimes. The concepts of path dependence and administrative traditions are used throughout. Self-reinforcing or positive feedback processes in political systems represent a basic framework. The empirical point of departure is the EU public procurement directive linked to OECD data concerning use of outsourcing among member states. The question is asked: What has caused the Nordic countries, traditionally not belonging to the Anglo-Saxon market-centred administrative tradition, to be placed so high on the ranking as users of the Market-Type Mechanism (MTM of outsourcing in the public sector vs. in-house provision of services? A thesis is that the reason may be complex, but might be found in an innovative Scandinavian regulatory approach rooted in the Nordic model.

  10. Improvement of plasma energy confinement in tokamak under radiative cooling of the edge plasma (United States)

    Razumova, K. A.; Borschegovskiy, A. A.; Gorbunov, E. P.; Dremin, M. M.; Kasyanova, N. V.; Kirneva, N. A.; Kislov, A. Ya.; Klyuchnikov, L. A.; Krupin, V. A.; Krylov, S. V.; Lysenko, S. E.; Melnikov, A. V.; Myalton, T. B.; Nemets, A. R.; Notkin, G. E.; Nurgaliev, M. R.; Sarychev, D. V.; Sushkov, A. V.; Chistyakov, V. V.; Ongena, J.; Messiaen, A.


    Improvement of plasma energy confinement in the T-10 tokamak by injection of impurity gases was studied experimentally. Injection of Ne and He in the ohmic and ECR heating regimes allows one to separate the dependences of energy confinement on the plasma density and on the edge plasma cooling rate. It is shown that the well-known dependence of the energy confinement time on the plasma density is, in fact, the dependence on the radiative loss power. This phenomenon can be explained by plasma self-organization. The experiments are described by a thermodynamic model for self-organized plasma in which the transport coefficient depends on the difference between the actual and self-consistent pressure profiles. The reduction in the heat flux at the plasma edge due to radiative cooling leads to a decrease in the transport coefficient in this region and, accordingly, improves energy confinement. Results of approximate model calculations for experiments with Ne injection are presented.

  11. Small to mid-sized stellarator experiments: topology, confinement and turbulence (United States)

    Harris, J. H.


    The very large stellarator experiments LHD (operating) and W7X (under construction) move stellarator-confined plasmas into the near-reactor regime. Continuing experiments on smaller devices operating at heating powers from kilowatts to a few megawatts are exploring the effects of magnetic configuration stability and turbulence on plasma confinement to improve stellarator performance and our understanding of general toroidal confinement physics. Key issues being explored are the relation of rational magnetic surfaces and magnetic configuration characteristics such as helical ripple to plasma transport, confinement scaling and turbulence. The robust macroscopic stability of currentless stellarator plasma is a major contributing factor to these studies. Many of the phenomena most clearly evident in stellarators are increasingly implicated in tokamak experiments as well.

  12. Energy-confinement scaling for high-beta plasmas in the W7-AS stellarator. (United States)

    Preuss, R; Dinklage, A; Weller, A


    High-beta energy-confinement data are subjected to comparisons of scaling invariant, first-principles physical models. The models differ in the inclusion of basic equations indicating the nature of transport. The result for high-beta data of the W7-AS stellarator is that global transport is described best with a collisional high-beta model, which is different from previous outcomes for low-beta data. Model predictive calculations indicate the validation of energy-confinement prediction with respect to plasma beta and collisionality nu*. The finding of different transport behaviors in distinct beta regimes is important for the development of fusion energy based on magnetic confinement and for the assessment of different confinement concepts.

  13. Confinement of color and geometry

    CERN Document Server

    Di Giacomo, A


    A natural explanation of confinement can be given in terms of symmetry. Since color symmetry is exact, the candidate symmetry is dual and related to homotopy,i.e., in (3+1)d, to magnetic charge conservation. A set of r abelian 'tHooft-like tensors (r = rank of the gauge group) can be defined and the dual charge is a violation of the corresponding Bianchi identities. It is shown that this is equivalently described by non-abelian Bianchi identities.

  14. Resilience of river flow regimes. (United States)

    Botter, Gianluca; Basso, Stefano; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea


    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. Here, we derive a measurable index embedding climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) that discriminates erratic regimes with enhanced intraseasonal streamflow variability from persistent regimes endowed with regular flow patterns. Theoretical and empirical data show that erratic hydrological regimes typical of rivers with low mean discharges are resilient in that they hold a reduced sensitivity to climate fluctuations. The distinction between erratic and persistent regimes provides a robust framework for characterizing the hydrology of freshwater ecosystems and improving water management strategies in times of global change.

  15. Effectiveness of International Environmental Regimes


    Beuck, Niels


    The Thesis analyzes the effecvtiveness of international environmental regimes. A case study of four of the most important river regimes in Germany - the Commissions for the Protection of the Rhine (ICPR), Elbe (ICPE), Oder (ICPO) and Lake Constance (IGKB)- was conducted. The first part of the thesis explains the theoretical foundation the thesis rests upon. Neoliberal Institutionalism was the chosen theory, accompanied by aspects of regime and game theory. A definition of effectiveness was ge...

  16. Resilience of river flow regimes


    Botter, G.; Basso, S.; Rodriguez-Iturbe, I.; Rinaldo, A.


    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. Here, we derive a measurable index embedding climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) that discriminates erratic regimes with...

  17. Electron confinement and heating in microwave-sustained argon microplasmas (United States)

    Hoskinson, Alan R.; Gregório, José; Parsons, Stephen; Hopwood, Jeffrey


    We systematically measure and model the behavior of argon microplasmas sustained by a broad range of microwave frequencies. The plasma behavior exhibits two distinct regimes. Up to a transition frequency of approximately 4 GHz, the electron density, directly measured by Stark broadening, increases rapidly with rising frequency. Above the transition frequency, the density remains approximately constant near 5 × 1020 m-3. The electrode voltage falls with rising frequency across both regimes, reaching approximately 5 V at the highest tested frequency. A fluid model of the plasma indicates that the falling electrode voltage reduces the electron temperature and significantly improves particle confinement, which in turn increases the plasma density. Particles are primarily lost to the electrodes at lower frequencies, but dissociative recombination becomes dominant as particle confinement improves. Recombination events produce excited argon atoms which are efficiently re-ionized, resulting in relatively constant ionization rates despite the falling electron temperature. The fast rates of recombination are the result of high densities of electrons and molecular ions in argon microplasmas.

  18. Exotic dense matter states pumped by relativistic laser plasma in the radiation dominant regime

    CERN Document Server

    Colgan, J; Jr.,; Faenov, A Ya; Pikuz, S A; Wagenaars, E; Booth, N; Brown, C R D; Culfa, O; Dance, R J; Evans, R G; Gray, R J; Hoarty, D J; Kaempfer, T; Lancaster, K L; McKenna, P; Rossall, A L; Skobelev, I Yu; Schulze, K S; Uschmann, I; Zhidkov, A G; Woolsey, N C


    The properties of high energy density plasma are under increasing scrutiny in recent years due to their importance to our understanding of stellar interiors, the cores of giant planets$^{1}$, and the properties of hot plasma in inertial confinement fusion devices$^2$. When matter is heated by X-rays, electrons in the inner shells are ionized before the valence electrons. Ionization from the inside out creates atoms or ions with empty internal electron shells, which are known as hollow atoms (or ions)$^{3,4,5}$. Recent advances in free-electron laser (FEL) technology$^{6,7,8,9}$ have made possible the creation of condensed matter consisting predominantly of hollow atoms. In this Letter, we demonstrate that such exotic states of matter, which are very far from equilibrium, can also be formed by more conventional optical laser technology when the laser intensity approaches the radiation dominant regime$^{10}$. Such photon-dominated systems are relevant to studies of photoionized plasmas found in active galactic ...

  19. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad


    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  20. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad


    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  1. Early regimes of water capillary flow in slit silica nanochannels. (United States)

    Oyarzua, Elton; Walther, Jens H; Mejía, Andrés; Zambrano, Harvey A


    Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibition of water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopic confinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillary filling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes: an initial regime where the capillary force is balanced only by the inertial drag and characterized by a constant velocity and a plug flow profile. In this regime, the meniscus formation process plays a central role in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance has significant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscous forces dominate the capillary force balance is attained. Flow velocity profiles identify the passage from an inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicate a transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling rates computed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.

  2. Millisecond burning of confined energetic materials during cookoff

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, R.G.; Baer, T.A.


    The response of a system containing an energetic material (EM) to an abnormal thermal environment is termed cookoff. To predict the violence of reaction of confined energetic materials during cookoff requires a description of the relevant physical processes that occur on time scales Ranging from days to submicroseconds. The time-to-ignition can be characterized accurately using heat transfer with chemistry and quasistatic mechanics. After ignition the energetic material deflagrates on a millisecond time scale. During this time the mechanical processes become dynamic. If the confinement survives burning then accelerated deflagration can lead to shock formation and deflagration to detonation transition. The focus of this work is the dynamic combustion regime in the millisecond time domain. Due to the mathematical stiffness of the chemistry equations and the prohibitively fine spatial resolution requirements needed to resolve the structure of the flame, an interface tracking approach is used to propagate the burn front. Demonstrative calculations are presented that illustrate the dynamic interaction of the deflagrating energetic material with its confinement.

  3. Collective excitations of a 87Rb Bose condensate in the Thomas-Fermi regime (United States)

    Fort, C.; Prevedelli, M.; Minardi, F.; Cataliotti, F. S.; Ricci, L.; Tino, G. M.; Inguscio, M.


    Collective excitations have been observed in a 87Rb Bose condensate, confined in a magneto-static, elongated, harmonic trap. We have measured the frequency of two different modes with zero angular momentum along the symmetry axis of the trap. Both the frequencies are in good agreement with the values predicted by the hydrodynamic theory of superfluids holding in the Thomas-Fermi regime.

  4. Confinement Effects on the Structure of Complex Fluids (United States)

    Kim, Mahn


    Actin is a key component of the protein complex responsible for producing contractile force in skeletal muscle. Filamentous actin, called F-actin, is a two-stranded helical protofilament with a diameter of ˜8nm and a contour length of ˜10m. The experimental results show that the persistence length of the F-actin is 4 -20 m. One of interesting problems is to find the structure of a semiflexible filament in a confined space [1], such as a channel width less than the persistence length. The other interesting problem is to find the surface treatment effect on the liquid crystal structure in a confined space. The boundary conditions imposed by the walls of the microchannel generate the spatial patterning of defect domains in a smectic liquid crystal [2] and the formation of a large-area ordered structure [3] by using the structure of smectic liquid in the microchannels. We found that the F-actin undergoes a transition from a 2D randomly oriented regime to a 1D biaxially confined regime with the effective persistence length. We were able to generate defect domains that are nearly uniformly arranged in 2D ordered patterns by controlling the surface hydrophobicity. Furthermore, the formation of a large-area ordered structure of toric focal conic domains was generated. This work was done with C. R. Safinya's group at UCSB and Hee-Tae Jung's group at KAIST. [4pt] [1] M.C Choi at. al, Macromolecules 2005,38, 9882-9884[0pt] [2] M. C. Choi at. al, PNAS 2004, 101, 17340-17344[0pt] [3] D. K. Yoon at. al, Nature Materials, 2007, 6, 866-870

  5. Stripe to slab confinement for the linearization of macromolecules in nanochannels. (United States)

    Benková, Zuzana; Námer, Pavol; Cifra, Peter


    We investigated the recently suggested advantageous analysis of chain linearization experiments with macromolecules confined in a stripe-like channel (Huang and Battacharya, EPL, 2014, 106, 18004) using Monte Carlo simulations. The enhanced chain extension in a stripe, which is due to the significant excluded volume interactions between the monomers in two dimensions, weakens considerably on transition to an experimentally feasible slit-like channel. Based on the chain extension-confinement strength dependence and the structure factor behavior for a chain in a stripe, we infer the excluded volume regime (de Gennes regime) typical for two-dimensional systems. On widening of the stripe in a direction perpendicular to the stripe plane, i.e. on the transition to the slab geometry, the advantageous chain extension decreases and a Gaussian regime is observed for not very long semiflexible chains. The evidence for pseudo-ideality in confined chains is based on four indicators: the extension curves, variation of the extension with the persistence length P, estimated limits for the regimes in the investigated systems, and the structure factor behavior. The slab behavior can be observed when the two-dimensional stripe (originally of a one-monomer thickness) reaches a reduced thickness D larger than approximately D/P ≈ 0.2 in the third dimension. This maximum height of a slab at which the advantage of a stripe is retained is very low and has implications for DNA linearization experiments.

  6. Effect of Aluminium Confinement on ANFO Detonation (United States)

    Short, Mark; Jackson, Scott; Kiyanda, Charles; Shinas, Mike; Hare, Steve; Briggs, Matt


    Detonations in confined non-ideal high explosives often have velocities below the confiner sound speed. The effect on detonation propagation of the resulting subsonic flow in the confiner (such as confiner stress waves traveling ahead of the main detonation front or upstream wall deflection into the HE) has yet to be fully understood. Previous work by Sharpe and Bdzil (J. Eng. Math, 2006) has shown that for subsonic confiner flow, there is no limiting thickness for which the detonation dynamics are uninfluenced by further increases in wall thickness. The critical parameters influencing detonation behavior are the wall thickness relative to the HE reaction zone size, and the difference in the detonation velocity and confiner sound speed. Additional possible outcomes of subsonic flow are that for increasing thickness, the confiner is increasingly deflected into the HE upstream of the detonation, and that for sufficiently thick confiners, the detonation speed could be driven up to the sound speed in the confiner. We report here on a further series of experiments in which a mixture of ammonium nitrate and fuel oil (ANFO) is detonated in aluminum confiners with varying HE charge diameter and confiner thickness, and compare the results with the outcomes suggested by Sharpe and Bdzil.

  7. Pneumatic fractures in confined granular media (United States)

    Eriksen, Fredrik K.; Toussaint, Renaud; Turquet, Antoine L.; Mâløy, Knut J.; Flekkøy, Eirik G.


    We perform experiments where air is injected at a constant overpressure Pin, ranging from 5 to 250 kPa, into a dry granular medium confined within a horizontal linear Hele-Shaw cell. The setup allows us to explore compacted configurations by preventing decompaction at the outer boundary, i.e., the cell outlet has a semipermeable filter such that beads are stopped while air can pass. We study the emerging patterns and dynamic growth of channels in the granular media due to fluid flow, by analyzing images captured with a high speed camera (1000 images/s). We identify four qualitatively different flow regimes, depending on the imposed overpressure, ranging from no channel formation for Pin below 10 kPa, to large thick channels formed by erosion and fingers merging for high Pin around 200 kPa. The flow regimes where channels form are characterized by typical finger thickness, final depth into the medium, and growth dynamics. The shape of the finger tips during growth is studied by looking at the finger width w as function of distance d from the tip. The tip profile is found to follow w (d ) ∝dβ , where β =0.68 is a typical value for all experiments, also over time. This indicates a singularity in the curvature d2d /d w2˜κ ˜d1 -2 β , but not of the slope d w /d d ˜dβ -1 , i.e., more rounded tips rather than pointy cusps, as they would be for the case β >1 . For increasing Pin, the channels generally grow faster and deeper into the medium. We show that the channel length along the flow direction has a linear growth with time initially, followed by a power-law decay of growth velocity with time as the channel approaches its final length. A closer look reveals that the initial growth velocity v0 is found to scale with injection pressure as v0∝Pin3/2 , while at a critical time tc there is a cross-over to the behavior v (t ) ∝t-α , where α is close to 2.5 for all experiments. Finally, we explore the fractal dimension of the fully developed patterns. For

  8. Chapter 5. Borderlands fire regimes (United States)

    Margot Wilkinson-Kaye; Thomas Swetnam; Christopher R. Baisan


    Fire is a keystone process in most natural, terrestrial ecosystems. The vital role that fire plays in controlling the structure of an ecosystem underscores the need for us to increase our knowledge of past and current fire regimes (Morgan and others 1994). Dendrochronological reconstructions of fire histories provide descriptions of past fire regimes across a range of...

  9. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein


    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of

  10. Confined space fatalities in Virginia. (United States)

    Sahli, B P; Armstrong, C W


    To better understand the frequency and characteristics of occupational confined space fatalities in Virginia, we reviewed death certificates, workers' compensation files, a Virginia Occupational Safety and Health Administration listing, and medical examiner records for all 50 fatalities (41 accidents) reported during 1979 to 1986. All fatalities were identified in medical examiner records (50), more than in any other source. The majority of decedents were male craftsmen, operators, or laborers less than 50 years old (mean 38). Drug screens of the 43 decedents tested were negative, with the exception of 2 cases where blood alcohol was detected (greater than or equal to 0.06%). Approximately 5% of "at work" civilian deaths (excluding plane, train, and motor vehicle fatalities) were confined space related. Virginia resident death rates per million employees were highest for shipbuilding and repair facilities (23.2), local government (8.9), and manufacturing other than shipbuilding (5.4%). Multiple fatalities occurred in 4 (10%) of the accidents, with 3 involving 2 fatalities each, and 1 accident involving 7 fatalities. Three fatalities (6%) were rescuers. Fifty nonfatal injuries of rescuers were known to have occurred in these accidents, 15 of co-workers and 35 of community rescue personnel (firefighters and rescue squad members). Approximately half the accidents occurred during the fourth quarter of the year and on a Thursday or Friday, and about one third occurred at night. The leading accident type was atmospheric condition, most commonly oxygen deficiency (33%) or the presence of carbon monoxide (20%). In 6 (40%) of the 15 accidents involving atmospheric condition, the toxic gas or oxygen deficiency was absent in the confined space at the time of entry.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. New advanced operational regime on the W7-AS stellarator. (United States)

    McCormick, K; Grigull, P; Burhenn, R; Brakel, R; Ehmler, H; Feng, Y; Gadelmeier, F; Giannone, L; Hildebrandt, D; Hirsch, M; Jaenicke, R; Kisslinger, J; Klinger, T; Klose, S; Knauer, J P; König, R; Kühner, G; Laqua, H P; Naujoks, D; Niedermeyer, H; Pasch, E; Ramasubramanian, N; Rust, N; Sardei, F; Wagner, F; Weller, A; Wenzel, U; Werner, A


    A promising new plasma operational regime on the Wendelstein stellarator W7-AS has been discovered. It is extant above a threshold density and characterized by flat density profiles, high energy and low impurity confinement times, and edge-localized radiation. Impurity accumulation is avoided. Quasistationary discharges with line-averaged densities n(e) to 4 x 10(20) m(-3), radiation levels to 90%, and partial plasma detachment at the divertor target plates can be simultaneously realized. Energy confinement is up to twice that of a standard scaling. At B(t) = 0.9 T, an average beta value of 3.1% is achieved. The high n(e) values allow demonstration of electron Bernstein wave heating using linear mode conversion.

  12. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J


    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force...

  13. Weak polyelectrolytes in Confined Geometries (United States)

    Whitmer, Jonathan K.; Rathee, Vikramjit S.; Sikora, Benjamin

    Crucial to the behavior of recently designed charge-rejection and mosaic membranes are the conformations of polyelectrolyte brushes and oligomeric grafts used to control the membranes' surface charge. The use of pH-tunable weak polyelectrolytes with associative interactions enables fine tuning of material transport properties. Here, we apply constant-pH molecular dynamics along with free energy sampling algorithms to understand the subtle tug-of-war between pH, salt concentrations, and solvation forces in confined systems, and determine how each of these effects alters transport within the system. We further discuss the implications of our findings for the design of electrolyte separation membranes.

  14. Magnetic bion condensation: A new mechanism of confinement and mass gap in four dimensions


    Unsal, Mithat


    In recent work, we derived the long-distance confining dynamics of certain QCD-like gauge theories formulated on small $S^1 \\times \\R^3$ based on symmetries, an index theorem, and Abelian duality. Here, we give the microscopic derivation. The solution reveals a new mechanism of confinement in QCD(adj) in the regime where we have control over both perturbative and nonperturbative aspects. In particular, consider SU(2) QCD(adj) theory with $1 \\leq n_f \\leq 4$ Majorana fermions, a theory which u...

  15. Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Robert A. [Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Center for Advanced Surface Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Goss, Josue A. [Center for Advanced Surface Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Zou, Min, E-mail: [Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Center for Advanced Surface Engineering, University of Arkansas, Fayetteville, AR 72701 (United States)


    Highlights: • Nanoindentation behavior of Al/a-Si core-shell nanostructures were studied. • 3D core confinement enables significant deformation recovery beyond elastic limit. • As the confinement is reduced, the deformation recovery is reduced or suppressed. • Atomistic simulations suggest core confinement affects dislocation dynamics. • 3D confinement has the highest percentage of dislocation removal after unloading. - Abstract: The nanoindentation behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), horizontally-aligned Al/a-Si core-shell nanorods (CSRs) with various lengths, and an Al/a-Si layered thin film has been studied to understand the effects of geometrical confinement of the Al core on the CSN deformation behavior. When loaded beyond the elastic limit, the CSNs have an unconventional load-displacement behavior with no residual displacement after unloading, resulting in no net shape change after indentation. This behavior is enabled by dislocation activities within the confined Al core, as indicated by discontinuous indentation signatures (load-drops and load-jumps) observed in the load-displacement data. When the geometrical confinement of the core is slightly reduced, as in the case of CSRs with the shortest rod length, the discontinuous indentation signatures and deformation resistance are heavily reduced. Further decreases in core confinement result in conventional nanoindentation behavior, regardless of geometry. Supporting molecular dynamics simulations show that dislocations nucleated in the core of a CSN are more effectively removed during unloading compared to CSRs, which supports the hypothesis that the unique deformation resistance of Al/a-Si CSNs are enabled by 3-dimensional confinement of the Al core.

  16. Effect of Core/Shell Interface on Carrier Dynamics and Optical Gain Properties of Dual-Color Emitting CdSe/CdS Nanocrystals. (United States)

    Pinchetti, Valerio; Meinardi, Francesco; Camellini, Andrea; Sirigu, Gianluca; Christodoulou, Sotirios; Bae, Wan Ki; De Donato, Francesco; Manna, Liberato; Zavelani-Rossi, Margherita; Moreels, Iwan; Klimov, Victor I; Brovelli, Sergio


    Two-color emitting colloidal semiconductor nanocrystals (NCs) are of interest for applications in multimodal imaging, sensing, lighting, and integrated photonics. Dual color emission from core- and shell-related optical transitions has been recently obtained using so-called dot-in-bulk (DiB) CdSe/CdS NCs comprising a quantum-confined CdSe core embedded into an ultrathick (∼7-9 nm) CdS shell. The physical mechanism underlying this behavior is still under debate. While a large shell volume appears to be a necessary condition for dual emission, comparison between various types of thick-shell CdSe/CdS NCs indicates a critical role of the interface "sharpness" and the presence of potential barriers. To elucidate the effect of the interface morphology on the dual emission, we perform side-by-side studies of CdSe/CdS DiB-NCs with nominally identical core and shell dimensions but different structural properties of the core/shell interface arising from the crystal structure of the starting CdSe cores (zincblende vs wurtzite). While both structures exhibit dual emission under comparable pump intensities, NCs with a zincblende core show a faster growth of shell luminescence with excitation fluence and a more readily realized regime of amplified spontaneous emission (ASE) even under "slow" nanosecond excitation. These distinctions can be linked to the structure of the core/shell interface: NCs grown from the zincblende cores contain a ∼3.5 nm thick zincblende CdS interlayer, which separates the core from the wurtzite CdS shell and creates a potential barrier for photoexcited shell holes inhibiting their relaxation into the core. This helps maintain a higher population of shell states and simplifies the realization of dual emission and ASE involving shell-based optical transitions.

  17. Geology, Surficial, Neuse River Basin Mapping Project Core Locations �Äö?Ñ?¨ Ongoing project in Middle Coastal Plain to characterize geomorphology, surficial geology, and shallow aquifers and confining units; Excel spread sheet with core names, coordinates, and data co, Published in 2006, 1:24000 (1in=2000ft) scale, North Carolina Department of Environment and Natural Resources (DENR). (United States)

    NSGIC State | GIS Inventory — Geology, Surficial dataset current as of 2006. Neuse River Basin Mapping Project Core Locations �Äö?Ñ?¨ Ongoing project in Middle Coastal Plain to characterize...

  18. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  19. Ice Cores (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  20. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W


    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  1. Hollow Core? (United States)

    Qiao, G. J.; Liu, J. F.; Wang, Yang; Wu, X. J.; Han, J. L.

    We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be $\\beta<0.5^\\circ$. The ``hollow core'' is in agreement with Inverse Compton Scattering model of radio pulsars.

  2. Magnetic confinement fusion energy research

    Energy Technology Data Exchange (ETDEWEB)

    Grad, H


    Controlled Thermonuclear Fusion offers probably the only relatively clean energy solution with completely inexhaustible fuel and unlimited power capacity. The scientific and technological problem consists in magnetically confining a hot, dense plasma (pressure several to hundreds of atmospheres, temperature 10/sup 8/ degrees or more) for an appreciable fraction of a second. The scientific and mathematical problem is to describe the behavior, such as confinement, stability, flow, compression, heating, energy transfer and diffusion of this medium in the presence of electromagnetic fields just as we now can for air or steam. Some of the extant theory consists of applications, routine or ingenious, of known mathematical structures in the theory of differential equations and in traditional analysis. Other applications of known mathematical structures offer surprises and new insights: the coordination between sub-supersonic and elliptic-hyperbolic is fractured; supersonic propagation goes upstream; etc. Other completely nonstandard mathematical structures with significant theory are being rapidly uncovered (and somewhat less rapidly understood) such as non-elliptic variational equations and new types of weak solutions. It is these new mathematical structures which one should expect to supply the foundation for the next generation's pure mathematics, if history is a guide. Despite the substantial effort over a period of some twenty years, there are still basic and important scintific and mathematical discoveries to be made, lying just beneath the surface.

  3. Topological defects in confined populations of spindle-shaped cells (United States)

    Duclos, Guillaume; Erlenkämper, Christoph; Joanny, Jean-François; Silberzan, Pascal


    Most spindle-shaped cells (including smooth muscles and sarcomas) organize in vivo into well-aligned `nematic’ domains, creating intrinsic topological defects that may be used to probe the behaviour of these active nematic systems. Active non-cellular nematics have been shown to be dominated by activity, yielding complex chaotic flows. However, the regime in which live spindle-shaped cells operate, and the importance of cell-substrate friction in particular, remains largely unexplored. Using in vitro experiments, we show that these active cellular nematics operate in a regime in which activity is effectively damped by friction, and that the interaction between defects is controlled by the system’s elastic nematic energy. Due to the activity of the cells, these defects behave as self-propelled particles and pairwise annihilate until all displacements freeze as cell crowding increases. When confined in mesoscopic circular domains, the system evolves towards two identical +1/2 disclinations facing each other. The most likely reduced positions of these defects are independent of the size of the disk, the cells’ activity or even the cell type, but are well described by equilibrium liquid crystal theory. These cell-based systems thus operate in a regime more stable than other active nematics, which may be necessary for their biological function.

  4. Phase segregation in a binary fluid confined inside a nanopore (United States)

    Basu, Saikat; Majumder, Suman; Sutradhar, Sabyasachi; Das, Subir K.; Paul, Raja


    Using a hydrodynamics preserving thermostat, we present extensive molecular dynamics simulation results for the kinetics of phase separation in a model binary (A+B) fluid confined inside a cylindrical nanopore with neutral wall. We observe the formation of a striped pattern, where A-rich and B-rich domains appear alternately along the axis of the cylinder. For a wide range of diameters of the cylinders, the growth of the pattern freezes and does not lead to complete phase separation. Prior to freezing, the growth of these stripes passes through two power-law regimes. The early-time regime is related to the Lifshitz-Slyozov diffusive mechanism and the estimated value of the exponent for the later-time regime matches well with that for the inertial hydrodynamic growth in three-dimensional fluid systems. Appropriate arguments have been provided to justify the observations. Furthermore, our results show that the length of the cylinder does not seem to affect the average axial length of the frozen patterns. However, the latter exhibits a linear dependence on the diameter of the cylinder.

  5. Bias dependence of sub-bandgap light detection for core-shell silicon nanowires. (United States)

    Zhou, Yuchun; Liu, Yu-hsin; Cheng, James; Lo, Yu-Hwa


    We experimentally demonstrate a vertically arrayed silicon nanowire-based device that exhibits voltage dependence of photoresponse to infrared sub-bandgap optical radiation. The device is fabricated using a proximity solid-state phosphorus diffusion method to convert the surface areas of highly boron-doped silicon nanowires into n-type, thus forming a radial core-shell p-n junction structure. Prominent photoresponse from such core-shell Si nanowires is observed under sub-bandgap illumination at 1310 nm. The strong bias dependence of the photoresponse and other device characteristics indicates that the sub-bandgap absorption is attributed to the intrinsic properties of core-shell Si nanowires rather than the surface states. The attractive characteristics are based on three physical mechanisms: the Franz-Keldysh effect, quasi-quantum confinement effect, and the impurity-state assisted photon absorption. The first two effects enhance carrier tunneling probability, rendering a stronger wave function overlap to facilitate sub-bandgap absorption. The last effect relaxes the k-selection rule by involving the localized impurity states, thus removing the limit imposed by the indirect bandgap nature of Si. The presented device uses single-crystal silicon and holds promise of fabricating nanophotonic systems in a fully complementary metal-oxide-semiconductor (CMOS) compatible process. The concept and approach can be applied to silicon and other materials to significantly extend the operable wavelength regime beyond the constraint of energy bandgap.

  6. Liquefaction Mitigation Using Lateral Confinement Technique

    Directory of Open Access Journals (Sweden)

    W. R. Azzam


    Full Text Available The exploration of a series of shaking tests on circular model footing with and without cellular confinement constructed around the footing with variable depths and diameters under the effect of variable net bearing stress is studied. The effect of the confinement on the liquefaction time, final settlement, excess pore water pressure, and induced building acceleration were studied. The consequences showed that installing the cell with minimum diameter closer to footing and sufficient penetration depth significantly delayed the liquefaction time. It can be considered as an alternative technique to decrease both the lateral spreading and the final settlement below the foundation during the shaking. The results demonstrated that the cell reduced the excess pore water pressure within the confined zone and the pore water pressure migration outside the confined block where the liquefaction is induced. Moreover, the peak foundation acceleration of the confined footing soil system is reduced compared with the case of without cell confinement.

  7. Spatially confined assembly of nanoparticles. (United States)

    Jiang, Lin; Chen, Xiaodong; Lu, Nan; Chi, Lifeng


    an increasingly important role in the controllable assembly of NPs. In this Account, we summarize our approaches and progress in fabricating spatially confined assemblies of NPs that allow for the positioning of NPs with high resolution and considerable throughput. The spatially selective assembly of NPs at the desired location can be achieved by various mechanisms, such as, a controlled dewetting process, electrostatically mediated assembly of particles, and confined deposition and growth of NPs. Three nanofabrication techniques used to produce prepatterns on a substrate are summarized: the Langmuir-Blodgett (LB) patterning technique, e-beam lithography (EBL), and nanoimprint lithography (NPL). The particle density, particle size, or interparticle distance in NP assemblies strongly depends on the geometric parameters of the template structure due to spatial confinement. In addition, with smart design template structures, multiplexed NPs can be assembled into a defined structure, thus demonstrating the structural and functional complexity required for highly integrated and multifunction applications.

  8. Detecting spatial regimes in ecosystems (United States)

    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological ...

  9. Quark Confinement and Force Unification

    Directory of Open Access Journals (Sweden)

    Stone R. A. Jr.


    Full Text Available String theory had to adopt a bi-scale approach in order to produce the weakness of gravity. Taking a bi-scale approach to particle physics along with a spin connection produces 1 the measured proton radius, 2 a resolution of the multiplicity of measured weak angle values 3 a correct theoretical value for the Z 0 4 a reason that h is a constant and 5 a “neutral current” source. The source of the “neutral current” provides 6 an alternate solution to quark confinement, 7 produces an effective r like potential, and 8 gives a reason for the observed but unexplained Regge trajectory like J M 2 behavior seen in quark composite particle spin families.

  10. Frictional properties of confined polymers. (United States)

    Sivebaek, I M; Samoilov, V N; Persson, B N J


    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force. The friction decreases when the sliding distance is of the order of the molecular length indicating a strong influence of molecular alignment during run-in. The results of our calculations show good correlation with experimental work.

  11. Crossover between Spatially Confined Precipitation and Periodic Pattern Formation in Reaction Diffusion Systems (United States)

    López Cabarcos, E.; Kuo, Chein-Shiu; Scala, A.; Bansil, R.


    We have observed a crossover between a spatially confined precipitation regime and periodic pattern formation regime. This unusual behavior was observed when electrolyte solutions of Na2HPO4 and CaCl2 were allowed to diffuse into an agarose gel from opposite ends. The formation of the confined precipitate occurs when the electrolyte flux J is the same at both sides of the gel. The time of formation and the width of the precipitate are a function of J and both follow the scaling relation ω~\\(J/D\\)-β with β = 0.40+/-0.2 and D the diffusion coefficient. The growth of periodic bands of precipitate was observed when J was different at both gel ends.

  12. Adaptation to natural flow regimes. (United States)

    Lytle, David A; Poff, N Leroy


    Floods and droughts are important features of most running water ecosystems, but the alteration of natural flow regimes by recent human activities, such as dam building, raises questions related to both evolution and conservation. Among organisms inhabiting running waters, what adaptations exist for surviving floods and droughts? How will the alteration of the frequency, timing and duration of flow extremes affect flood- and drought-adapted organisms? How rapidly can populations evolve in response to altered flow regimes? Here, we identify three modes of adaptation (life history, behavioral and morphological) that plants and animals use to survive floods and/or droughts. The mode of adaptation that an organism has determines its vulnerability to different kinds of flow regime alteration. The rate of evolution in response to flow regime alteration remains an open question. Because humans have now altered the flow regimes of most rivers and many streams, understanding the link between fitness and flow regime is crucial for the effective management and restoration of running water ecosystems.

  13. Modeling hydrodynamic instabilities of double ablation fronts in inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    Yanez C.


    Full Text Available A linear Rayleigh-Taylor instability theory of double ablation (DA fronts is developed for direct-drive inertial confinement fusion. Two approaches are discussed: an analytical discontinuity model for the radiation dominated regime of very steep DA front structure, and a numerical self-consistent model that covers more general hydrodynamic profiles behaviours. Dispersion relation results are compared to 2D simulations.

  14. Determination of oscillator strength of confined excitons in a semiconductor microcavity

    Directory of Open Access Journals (Sweden)

    E.A. Cotta


    Full Text Available We have achieved a significant experimental Rabi-splitting (3.4 meV for confined polaritons in a planar semiconductor λ microcavity for only a single quantum well (SQW of GaAs (10 nm placed at the antinode. The Rabi-splitting phenomena are discussed in detail based on the semiclassical theory, where two coupled harmonic oscillators (excitons and photons are used to describe the system. In this way, we can obtain the dispersion curve of polaritons, the minimum value for the cavity reflectance and the oscillator strength to reach the strong coupling regime. This approach describes an ensemble of excitons confined in a SQW and includes a dissipation component. The results present a weak coupling regime, where an enhanced spontaneous emission takes place, and a strong coupling regime, where Rabi-splitting in the dispersion curve can be observed. The theoretical results are confronted with experimental data for the reflectance behavior in resonant and off-resonant conditions and present a great accuracy. This allows us to determine the oscillator strength of the confined excitons in the SQW with great precision.

  15. Formation of Multicharged Ions at Quasi-Gasdynamic Plasma Confinement in a Mirror trap

    CERN Document Server

    Golubev, S V; Semenov, V E; Smirnov, A N; Vodopyanov, A S; Zorin, V G


    It was shown in [1] that an increase in plasma density Ne in sources of multicharged ions leads to a substantial increase of ion current and improves slightly the ion distribution over charge states. Validity of this statement was verified in experiments with plasma densities not exceeding several units of 1012 cm-3. It was revealed [2] that, for the electron densities exceeding 1013 cm-3, the regime of plasma confinement in a trap changes significantly, the scaling described in [1] is no longer valid, and the quasi-gasdynamic regime of plasma confinement is realized. The plasma confinement time ti in this regime weakly depends on electron density. Consequently, the parameter governing formation of multicharged ions, Neti , grows as the electron density is increased. This means that an increase in plasma density results not only in an increase in the total ion current but also in the shift of the ion charge state distribution towards higher charge states. The present work concerns experimental investigation o...

  16. Pedestal and confinement properties under shape and magnetic topology variation on Alcator C-Mod (United States)

    Hughes, J. W.; Lipschultz, B.; Whyte, D.; Marmar, E. S.; Greenwald, M.; Hubbard, A. E.; McDermott, R. M.


    Recent work on Alcator C-Mod has examined the influence of magnetic topology and equilibrium shape on edge pedestal structure and plasma confinement. H-mode pedestal parameters show a striking sensitivity to the ion ∇B drift direction, relative to the active x-point position, with considerable variability observed when the distance between separatrices is on the order of the pedestal width (˜5mm) or less, i.e. very near double null (DN). Near DN H-modes can have improved confinement factors (H98>1) as a result of elevated pedestal temperature (Tped), with the edge regulated by benign small edge-localized modes (ELMs) or continuous modes. Such operational regimes with no large ELMs are desirable for ITER and other future devices. Discharges with L-mode-like particle confinement, yet with H98 1 and Tped 1keV, were maintained steady-state by operating with high current, strong shaping and unfavorable ∇B drift direction, while holding input power below the L-H threshold to prevent particle barrier formation. The pedestal and confinement properties of these improved ELM-free regimes will be compared to those of typical H-modes.

  17. Anomalous diffusion and diffusion anomaly in confined Janus dumbbells (United States)

    Krott, Leandro B.; Gavazzoni, Cristina; Bordin, José Rafael


    Self-assembly and dynamical properties of Janus nanoparticles have been studied by molecular dynamic simulations. The nanoparticles are modeled as dimers and they are confined between two flat parallel plates to simulate a thin film. One monomer from the dumbbells interacts by a standard Lennard-Jones potential and the other by a two-length scales shoulder potential, typically used for anomalous fluids. Here, we study the effects of removing the Brownian effects, typical from colloidal systems immersed in aqueous solution, and consider a molecular system, without the drag force and the random collisions from the Brownian motion. Self-assembly and diffusion anomaly are preserved in relation to the Brownian system. Additionally, a superdiffusive regime associated to a collective reorientation in a highly structured phase is observed. Diffusion anomaly and anomalous diffusion are explained in the two length scale framework.

  18. Holographic thermalization in a top-down confining model

    Energy Technology Data Exchange (ETDEWEB)

    Craps, B. [Theoretische Natuurkunde, Vrije Universiteit Brussel, and International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium); Lindgren, E.J. [Theoretische Natuurkunde, Vrije Universiteit Brussel, and International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium); Physique Théorique et Mathématique, Université Libre de Bruxelles,Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Taliotis, A. [Theoretische Natuurkunde, Vrije Universiteit Brussel, and International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)


    It is interesting to ask how a confinement scale affects the thermalization of strongly coupled gauge theories with gravity duals. We study this question for the AdS soliton model, which underlies top-down holographic models for Yang-Mills theory and QCD. Injecting energy via a homogeneous massless scalar source that is briefly turned on, our fully backreacted numerical analysis finds two regimes. Either a black brane forms, possibly after one or more bounces, after which the pressure components relax according to the lowest quasinormal mode. Or the scalar shell keeps scattering, in which case the pressure components oscillate and undergo modulation on time scales independent of the (small) shell amplitude. We show analytically that the scattering shell cannot relax to a homogeneous equilibrium state, and explain the modulation as due to a near-resonance between a normal mode frequency of the metric and the frequency with which the scalar shell oscillates.

  19. Strong coupling and degeneracy effects in inertial confinement fusion implosions. (United States)

    Hu, S X; Militzer, B; Goncharov, V N; Skupsky, S


    Accurate knowledge about the equation of state (EOS) of deuterium is critical to inertial confinement fusion (ICF). Low-adiabat ICF implosions routinely access strongly coupled and degenerate plasma conditions. Using the path integral Monte Carlo method, we have derived a first-principles EOS (FPEOS) table of deuterium. It is the first ab initio EOS table which completely covers typical ICF implosion trajectory in the density and temperature ranges of ρ=0.002-1596  g/cm3 and T=1.35  eV-5.5  keV. Discrepancies in internal energy and pressure have been found in strongly coupled and degenerate regimes with respect to SESAME EOS. Hydrodynamics simulations of cryogenic ICF implosions using the FPEOS table have indicated significant differences in peak density, areal density (ρR), and neutron yield relative to SESAME simulations.

  20. Madness and crime: Zefinha, the longest confined woman in Brazil. (United States)

    Diniz, Debora; Brito, Luciana


    Living in a forensic hospital for the last 38 years, Josefa da Silva is the longest female inhabitant surviving the penal and psychiatric regime in Brazil. This paper analyses dossier, judicial proceedings, interviews and photographs about her. The psychiatric report is the key component of the medical and penal doubling of criminal insanity. Twelve psychiatric reports illustrate three time frames of the court files: abnormality, danger, and abandonment. The psychiatric authority over confinement has moved from discipline to security, and from disciplinary security to social assistance. In the arrangement between the penal and psychiatric powers, the judge recognizes the medical authority over the truth of insanity. It is the medicine of the reasons for Zefinha's internment that altered over the decades.

  1. Degraded confinement and turbulence in tokamak experiments

    NARCIS (Netherlands)

    Schüller, F. C.


    After a review on the state of tokamak transport theory, the methodology to derive experimental results will be described. Examples of confinement in ohmic plasmas and the deterioration with additional heating will be given. Some examples of improved confinement modes will be discussed. Fluctuation

  2. Degraded confinement and turbulence in tokamak experiments

    NARCIS (Netherlands)

    Hogeweij, G. M. D.


    After a review on the state of tokamak transport theory, the methodology to derive experimental results will be described. Examples of confinement in ohmic plasmas and the deterioration with additional healing will be given. Some examples of improved confinement; modes will be discussed.

  3. Confinement of charge carriers in bilayer graphene

    NARCIS (Netherlands)

    Goossens, A.M.


    In this thesis we investigate the fundamental properties of electronic transport in bilayer graphene. We do this by confining electrons to narrow constrictions and small islands. Our key result is the fabrication and measurement of nanoscale devices that permit confinement with electric fields in

  4. Structure of polymer chains under confinement

    Indian Academy of Sciences (India)

    Single chain form factor was observed both for bulk and confined chains using the condition of zero average contrast. Our measurements on neutral polymer chains are in agreement with the theoretical predictions established by Daoud and de Gennes for chains confined in a cylindrical pore when the chains are entangled ...


    Directory of Open Access Journals (Sweden)

    BENEA Ciprian-Beniamin


    Full Text Available The history of diplomacy can by divided in three main periods: one is that of occasional diplomacy peculiar to Middle Ages, while other belong to permane diplomacy, peculiar to modern times. But this one can be divided in two parts, too: one with a bilateral character, previos to 1st World War, and one with a multilateral character, manifested especially after the end on 1st World War. This third type is the focus of present paper. And it cannot be separated from the newly international constructs: international regimes, and international organizations. International instritutions the area where international regimes are belonging to – are legal constructs which provide the formal (and legal framework for continous negotiations. They are the most visible part of the new diplomacy – the one which has a permanent character, and it has an more open face. Anyway, the most important connection has to do with the international institutions, international regimes, and multilateral international negotiations. In the era of the new diplomacy, they all have a permanent character. International institutions help international negotiations carring on; while in their turn, they provide the base for international regimes’ creation, and especially for their evolution. The international regimes’ evolution is an inseparable part of a permanent international framework. And if there is missing a permanent international framework (international organization connected to a specific regime, this regime is a difuse one, its members have only informal relations among them, while they survey each other, looking at their behavior, but they don’t have a formal relationship among them, which could help them solving their future common interests, and protect them from their common fears. International regimes are very important in the era when evrithing touches, and influences everything. In the same time, the complexity of our present world can be successfully

  6. Polymer Dynamics under Cylindrical Nano-Confinement (United States)

    Winey, Karen; Tung, Wei-Shao; Riggleman, Robert


    Polymer melts under cylindrical confinement have previously been shown to exhibit chain conformations elongated parallel to the cylinder axis and compressed perpendicular to the cylinder. Further, simulations and theory found that the number of entanglements per chain decreases as the cylinder diameter decreases. This talk presents the local dynamics and polymer diffusion under cylindrical nanoconfinement using simulations and experiments. For the molecular dynamics simulations, an entangled polymer is confined by an amorphous cylindrical confinement. Local dynamics and local packing of monomers are affected by the cylindrical confinement and an anisotropic mean-squared displacement is observed with faster motion along the cylinder axes that increases with increasing confinement. Using elastic recoil detection experiments, polymer diffusion coefficients along cylindrical nanopores were measured for deuterated polystyrene diffusing into nanoporous membranes infiltrated with polystyrene. The tracer diffusion coefficient increased with decreasing pore size, although the increase is less pronounced than found in the simulations. Results will be discussed in terms of the reptation model.

  7. High confinement dissipative divertor operation on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, J.A.; LaBombard, B.; Lipschultz, B.; Pitcher, C.S.; Terry, J.L.; Boswell, C.; Gangadhara, S.; Pappas, D.; Weaver, J.; Welch, B.; Boivin, R.L.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hubbard, A.; Hutchinson, I.; Irby, J.; Marmar, E.; Mossessian, D.; Porkolab, M.; Rice, J.; Rowan, W.L.; Schilling, G.; Snipes, J.; Takase, Y.; Wolfe, S.; Wukitch, S. [Plasma Science Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    Alcator C-Mod [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)] has operated a High-confinement-mode (H-mode) plasma together with a dissipative divertor and low core Z{sub eff}. The initially attached plasma is characterized by steady-state enhancement factor, H{sub ITER89P} [P. N. Yushmanov {ital et al.}, Nucl. Fusion {bold 30}, 1999 (1990)], of 1.9, central Z{sub eff} of 1.1, and a radiative fraction of {approximately}50{percent}. Feedback control of a nitrogen gas puff is used to increase radiative losses in both the core/edge and divertor plasmas in almost equal amounts. Simultaneously, the core plasma maintains H{sub ITER89P} of 1.6 and Z{sub eff} of 1.4 in this nearly 100{percent} radiative state. The power and particle flux to the divertor plates have been reduced to very low levels while the core plasma is relatively unchanged by the dissipative nature of the divertor. {copyright} {ital 1999 American Institute of Physics.}

  8. Ultra low bending loss equiangular spiral photonic crystal fibers in the terahertz regime

    Directory of Open Access Journals (Sweden)

    Arti Agrawal


    Full Text Available An Equiangular Spiral Photonic Crystal Fiber (ES-PCF design in Topas® for use in the Terahertz regime is presented. The design shows ultra low bending loss and very low confinement loss compared to conventional Hexagonal PCF (H-PCF. The ES-PCF has excellent modal confinement properties, together with several parameters to allow the optimization of the performance over a range of important characteristics. A full vector Finite Element simulation has been used to characterize the design which can be fabricated by a range of techniques including extrusion and drilling.

  9. Fermion Superfluidity And Confining Interactions

    CERN Document Server

    Galal, A A


    We study the pairing of Fermi systems with long-range, confining interparticle interactions. We solve the Cooper problem for a pair of fermions interacting via a regularized harmonic oscillator potential and determine the s-wave spectrum of bound states. Using a model of two interacting species of fermions, we calculate the ground state energy of the normal phase in the Hartree-Fock approximation and find that it is infrared (IR) divergent, due to a combination of the sharpness of the Fermi sea and the long-range nature of the interaction. We calculate the correlation energy in the normal phase using the random phase approximation (RPA) and demonstrate the cancellation of infrared divergences between the Hartree-Fock and RPA contributions. Introducing a variational wavefunction to study the superfluid phase, we solve the BCS equations using a Hartree-Fock-Bogoliubov (HFB) analysis to determine the wave-function, excitation gap, and other parameters of the superfluid phase. We show that the system crosses over...

  10. Thermalization and confinement in strongly coupled gauge theories

    Directory of Open Access Journals (Sweden)

    Ishii Takaaki


    Full Text Available Quantum field theories of strongly interacting matter sometimes have a useful holographic description in terms of the variables of a gravitational theory in higher dimensions. This duality maps time dependent physics in the gauge theory to time dependent solutions of the Einstein equations in the gravity theory. In order to better understand the process by which “real world” theories such as QCD behave out of thermodynamic equilibrium, we study time dependent perturbations to states in a model of a confining, strongly coupled gauge theory via holography. Operationally, this involves solving a set of non-linear Einstein equations supplemented with specific time dependent boundary conditions. The resulting solutions allow one to comment on the timescale by which the perturbed states thermalize, as well as to quantify the properties of the final state as a function of the perturbation parameters. We comment on the influence of the dual gauge theory’s confinement scale on these results, as well as the appearance of a previously anticipated universal scaling regime in the “abrupt quench” limit.

  11. Confining energy migration in upconversion nanoparticles towards deep ultraviolet lasing (United States)

    Chen, Xian; Jin, Limin; Kong, Wei; Sun, Tianying; Zhang, Wenfei; Liu, Xinhong; Fan, Jun; Yu, Siu Fung; Wang, Feng


    Manipulating particle size is a powerful means of creating unprecedented optical properties in metals and semiconductors. Here we report an insulator system composed of NaYbF4:Tm in which size effect can be harnessed to enhance multiphoton upconversion. Our mechanistic investigations suggest that the phenomenon stems from spatial confinement of energy migration in nanosized structures. We show that confining energy migration constitutes a general and versatile strategy to manipulating multiphoton upconversion, demonstrating an efficient five-photon upconversion emission of Tm3+ in a stoichiometric Yb lattice without suffering from concentration quenching. The high emission intensity is unambiguously substantiated by realizing room-temperature lasing emission at around 311 nm after 980-nm pumping, recording an optical gain two orders of magnitude larger than that of a conventional Yb/Tm-based system operating at 650 nm. Our findings thus highlight the viability of realizing diode-pumped lasing in deep ultraviolet regime for various practical applications. PMID:26739352

  12. Scattering resonances of ultracold atoms in confined geometries

    Energy Technology Data Exchange (ETDEWEB)

    Saeidian, Shahpoor


    Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)

  13. PCF Based Sensor with High Sensitivity, High Birefringence and Low Confinement Losses for Liquid Analyte Sensing Applications

    Directory of Open Access Journals (Sweden)

    Huseyin Ademgil


    Full Text Available In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures. We show that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes.

  14. On the regimes of premixing

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, S.; Theofanous, T.G.; Yuen, W.W. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety


    The conditions of the MAGICO-2000 experiment are extended to more broadly investigate the regimes of premixing, and the corresponding internal structures of mixing zones. With the help of the data and numerical simulations using the computer code PM-ALPHA, we can distinguish extremes of behavior dominated by inertia and thermal effects - we name these the inertia and thermal regimes, respectively. This is an important distinction that should guide future experiments aimed at code verification in this area. Interesting intermediate behaviors are also delineated and discussed. (author)

  15. The Choice of Monetary Regime

    DEFF Research Database (Denmark)

    Østrup, Finn

    The article examines how government spending is determined in a closedeconomy where the nominal wage is pre-set through contracts and the wage settershave perfect foresight regarding subsequent policy decisions. The monetaryregime affects government spending because: (i) with a pre-set nominal wa......, a comparisonbetween monetary regimes suggests that welfare is highest under nominalincome targeting where the nominal income target is determined to bring aboutprice stability.Keywords: Monetary regimes; fiscal policy; monetary non-neutrality.JEL classicification: E42, E61, E62....

  16. Experimental and analytical investigation of the lateral load response of confined masonry walls

    Directory of Open Access Journals (Sweden)

    Hussein Okail


    Full Text Available This paper investigates the behavior of confined masonry walls subjected to lateral loads. Six full-scale wall assembles, consisting of a clay masonry panel, two confining columns and a tie beam, were tested under a combination of vertical load and monotonic pushover up to failure. Wall panels had various configurations, namely, solid and perforated walls with window and door openings, variable longitudinal and transverse reinforcement ratios for the confining elements and different brick types, namely, cored clay and solid concrete masonry units. Key experimental results showed that the walls in general experienced a shear failure at the end of the lightly reinforced confining elements after the failure of the diagonal struts formed in the brick wall due to transversal diagonal tension. Stepped bed joint cracks formed in the masonry panel either diagonally or around the perforations. A numerical model was built using the finite element method and was validated in light of the experimental results. The model showed acceptable correlation and was used to conduct a thorough parametric study on various design configurations. The conducted parametric study involved the assessment of the load/displacement response for walls with different aspect ratios, axial load ratios, number of confining elements as well as the size and orientation of perforations. It was found that the strength of the bricks and the number of confining elements play a significant role in increasing the walls’ ultimate resistance and displacement ductility.

  17. Aerofractures in Confined Granular Media (United States)

    Eriksen, Fredrik K.; Turkaya, Semih; Toussaint, Renaud; Måløy, Knut J.; Flekkøy, Eirik G.


    We will present the optical analysis of experimental aerofractures in confined granular media. The study of this generic process may have applications in industries involving hydraulic fracturing of tight rocks, safe construction of dams, tunnels and mines, and in earth science where phenomena such as mud volcanoes and sand injectites are results of subsurface sediment displacements driven by fluid overpressure. It is also interesting to increase the understanding the flow instability itself, and how the fluid flow impacts the solid surrounding fractures and in the rest of the sample. Such processes where previously studied numerically [Niebling 2012a, Niebling 2012b] or in circular geometries. We will here explore experimentally linear geometries. We study the fracturing patterns that form when air flows into a dense, non-cohesive porous medium confined in a Hele-Shaw cell - i.e. into a packing of dry 80 micron beads placed between two glass plates separated by ~1mm. The cell is rectangular and fitted with a semi-permeable boundary to the atmosphere - blocking beads but not air - on one short edge, while the other three edges are impermeable. The porous medium is packed inside the cell between the semi-permeable boundary and an empty volume at the sealed side where the air pressure can be set and kept at a constant overpressure (1-2bar). Thus, for the air trapped inside the cell to release the overpressure it has to move through the solid. At high enough overpressures the air flow deforms the solid and increase permeability in some regions along the air-solid interface, which results in unstable flow and aerofracturing. Aerofractures are thought to be an analogue to hydrofractures, and an advantage of performing aerofracturing experiments in a Hele-Shaw cell is that the fracturing process can easily be observed in the lab. Our experiments are recorded with a high speed camera with a framerate of 1000 frames per second. In the analysis, by using various image

  18. Bifurcation to chaos in the Benard-Marangoni instability in a confined geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rahal, S [Department of Mechanical Engineering, University of Batna, Rue Boukhlouf Mohamed el Hadi, 05000 Batna (Algeria); Cerisier, P [IUSTI - CNRS UMR 6595, Polytech' Marseille, Technopole de Chateau-Gombert, 5 rue Enrico Fermi, 13453, Marseille Cedex 13 (France)


    An experimental study of dynamical regimes in Benard-Marangoni convection, for various Prandt and Marangoni numbers, has been carried out in a confined geometry. Indeed, a small hexagonal vessel allowing the formation of only one convective cell, for a large extent of the Marangoni number, has been used. Fourrier spectra and a correlation function have been used to recognize the various dynamical regimes. For fixed values of the Prantl number and aspect ratio, an oscillatory, a quasi-periodic and chaotic states, were successively observed, as the Marangoni number was increased. The correlation dimensions of strange attractors corresponding to the chaotic regimes were calculated. The dimensions were found to be larger then those calculated by other authors for the Rayleigh-Benard convection in small aspect ratio geometries. The transition from temporal chaos to spatio - temporal chaos has also been observed. Indeed for higher values of the Marangoni number, spatial dynamics are observed.

  19. Controlling Confinement with Induced Toroidal Current in the Flexible Heliac TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J. A.; Lopez-Bruna, D.; Lopez-Fraguas, A.; Ascasibar, E.; TJ-II Team


    A method to control plasma particle an energy confinement in the TJ-II Heliac devices is reported A small toroidal current is induced in the plasma with the aid of a 0.2 Wb air core transformer. Plasma particle and energy confinement improve (degrade) with negative (positive) plasma current. For typical TJ-II discharges plasma density and temperature broaden considerably when plasma current is sufficiently negative, accounting for a 40% increase in stored energy. The experimental results agree qualitatively with the paradigm of instability growth rate modifications with magnetic shear. (Author) 18 refs.

  20. Bursting of a bubble confined in between two plates (United States)

    Murano, Mayuko; Kimono, Natsuki; Okumura, Ko


    Rupture of liquid thin films, driven by surface tension, has attracted interests of scientists for many years. It is also a daily phenomenon familiar to everyone in the form of the bursting of soap films. In recent years, many studies in confined geometries (e.g. in a Hele-Shaw cell) have revealed physical mechanisms of the dynamics of bubbles and drops. As for a liquid film sandwiched in between another liquid immiscible to the film liquid in the Hele-Shaw cell, it is reported that the thin film bursts at a constant speed and the speed depends on the viscosity of the surrounding liquid when the film is less viscous, although a rim is not formed at the bursting tip; this is because the circular symmetry of the hole in the bursting film is lost. Here, we study the bursting speed of a thin film sandwiched between air instead of the surrounding liquid in the Hele-Shaw cell to seek different scaling regimes. By measuring the bursting velocity and the film thickness of an air bubble with a high speed camera, we have found a new scaling law in viscous regime. This research was partly supported by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan).

  1. Absence of reptation in highly confined polymers. (United States)

    Srivastava, S; Basu, J K


    We present results of mechanical stress relaxation measurements on polymers confined at the air-water interface in the form of a monolayer. Systematic measurements allow, to our knowledge, for the first time, observation of the scaling of the stress relaxation time of the highly confined polymers as a function of both surface concentration and molecular weight. The observed scaling is found to be very close to that expected for motion of unentangled polymer solutions with hydrodynamic interactions. Our experimental observations thus clearly rule out the possibility of entanglement and hence reptation as a mode of relaxation in such highly confined polymeric systems.

  2. Kinetics of Phase Separation in Confined Geometries (United States)

    Puri, Sanjay

    We review analytical and numerical results for the kinetics of phase separation in confined geometries. It is often the case that a confining surface has a preferential attraction for one of the components of a segregating mixture. The equilibrium surface morphology is either partially wet or completely wet, depending on the strength of the surface potential. The dynamical interplay of wetting and phase separation is referred to as surface-directed spinodal decomposition (SDSD), and is of considerable technological importance. We discuss the modeling of SDSD at both the microscopic and coarse-grained levels. We also present results for SDSD in both semi-infinite and confined geometries.

  3. Building the chemical disarmament regime

    Energy Technology Data Exchange (ETDEWEB)

    Herby, P.


    While the good news is that the commission responsible for settling the technical aspects of the Chemical Weapons Convention`s (CWC) complex verification regime has made significant progress, the fate of the CWC now lies increasingly with people with little previous familiarity with the convention.

  4. Monetary regimes in open economies

    NARCIS (Netherlands)

    Korpos, A.


    This thesis presents a two-country open economy framework for the analysis of strategic interactions among monetary authorities and wage bargaining institutions. From this perspective, the thesis investigates the economic consequences of replacing flexible and fixed exchange rate regimes with a

  5. Highly episodic fire and erosion regime over the past 2,000 y in the Siskiyou Mountains, Oregon

    National Research Council Canada - National Science Library

    Daniele Colombaroli; Daniel G. Gavin; John P. Smol


    ... fire compared with presettlement forests. To reconstruct the variability of the fire regime in the Siskiyou Mountains, Oregon, we analyzed a 10-m, 2,000-y sediment core for charcoal, pollen, and sedimentological data...

  6. Electrically tunable single-dot nanocavities in the weak and strong coupling regimes

    DEFF Research Database (Denmark)

    Laucht, Arne; Hofbauer, Felix; Angele, Jacob


    was varied by changing the lattice temperature [2,3], or by the adsorption of inert-gases at low temperatures [4], we demonstrate that the quantum confined Stark effect can be employed to quickly and reversibly switch the dot-cavity coupling, simply by varying a gate voltage [1]. Our results show...... of the emitted photons from a single-dot nanocavity in the weak and strong coupling regimes. New information is obtained on the nature of the dot-cavity coupling in the weak coupling regime and electrical control of zero dimensional polaritons is demonstrated for the first time. Vacuum Rabi splittings up to 2g...

  7. Iron snow in the Martian core? (United States)

    Davies, Christopher J.; Pommier, Anne


    The decline of Mars' global magnetic field some 3.8-4.1 billion years ago is thought to reflect the demise of the dynamo that operated in its liquid core. The dynamo was probably powered by planetary cooling and so its termination is intimately tied to the thermochemical evolution and present-day physical state of the Martian core. Bottom-up growth of a solid inner core, the crystallization regime for Earth's core, has been found to produce a long-lived dynamo leading to the suggestion that the Martian core remains entirely liquid to this day. Motivated by the experimentally-determined increase in the Fe-S liquidus temperature with decreasing pressure at Martian core conditions, we investigate whether Mars' core could crystallize from the top down. We focus on the "iron snow" regime, where newly-formed solid consists of pure Fe and is therefore heavier than the liquid. We derive global energy and entropy equations that describe the long-timescale thermal and magnetic history of the core from a general theory for two-phase, two-component liquid mixtures, assuming that the snow zone is in phase equilibrium and that all solid falls out of the layer and remelts at each timestep. Formation of snow zones occurs for a wide range of interior and thermal properties and depends critically on the initial sulfur concentration, ξ0. Release of gravitational energy and latent heat during growth of the snow zone do not generate sufficient entropy to restart the dynamo unless the snow zone occupies at least 400 km of the core. Snow zones can be 1.5-2 Gyrs old, though thermal stratification of the uppermost core, not included in our model, likely delays onset. Models that match the available magnetic and geodetic constraints have ξ0 ≈ 10% and snow zones that occupy approximately the top 100 km of the present-day Martian core.

  8. Boundary perturbations coupled to core 3/2 tearing modes on the DIII-D tokamak

    NARCIS (Netherlands)

    Tobias, B.; Yu, L.; Domier, C.W.; N C Luhmann Jr.,; Austin, M. E.; Paz-Soldan, C.; Turnbull, A. D.; Classen, I.G.J.


    High confinement (H-mode) discharges on the DIII-D tokamak are routinely subject to the formation of long-lived, non-disruptive magnetic islands that degrade confinement and limit fusion performance. Simultaneous, 2D measurement of electron temperature fluctuations in the core and edge regions

  9. Electronic Quantum Confinement in Cylindrical Potential Well

    CERN Document Server

    Baltenkov, A S


    The effects of quantum confinement on the momentum distribution of electrons confined within a cylindrical potential well have been analyzed. The motivation is to understand specific features of the momentum distribution of electrons when the electron behavior is completely controlled by the parameters of a non-isotropic potential cavity. It is shown that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the three-dimensional space within the framework of the same mathematical model. Some low-lying electronic states with different symmetries have been considered and the corresponding wave functions have been calculated; the behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well has been analyzed. Additionally, the momentum distributions of electrons in these states have been calculated. The limi...

  10. Plasma confinement system and methods for use

    Energy Technology Data Exchange (ETDEWEB)

    Jarboe, Thomas R.; Sutherland, Derek


    A plasma confinement system is provided that includes a confinement chamber that includes one or more enclosures of respective helicity injectors. The one or more enclosures are coupled to ports at an outer radius of the confinement chamber. The system further includes one or more conductive coils aligned substantially parallel to the one or more enclosures and a further set of one or more conductive coils respectively surrounding portions of the one or more enclosures. Currents may be provided to the sets of conductive coils to energize a gas within the confinement chamber into a plasma. Further, a heat-exchange system is provided that includes an inner wall, an intermediate wall, an outer wall, and pipe sections configured to carry coolant through cavities formed by the walls.

  11. Anisotropic hydrodynamic function of dense confined colloids (United States)

    Nygârd, Kim; Buitenhuis, Johan; Kagias, Matias; Jefimovs, Konstantins; Zontone, Federico; Chushkin, Yuriy


    Dense colloidal dispersions exhibit complex wave-vector-dependent diffusion, which is controlled by both direct particle interactions and indirect nonadditive hydrodynamic interactions mediated by the solvent. In bulk the hydrodynamic interactions are probed routinely, but in confined geometries their studies have been hitherto hindered by additional complications due to confining walls. Here we solve this issue by combining high-energy x-ray photon correlation spectroscopy and small-angle x-ray-scattering experiments on colloid-filled microfluidic channels to yield the confined fluid's hydrodynamic function in the short-time limit. Most importantly, we find the confined fluid to exhibit a strongly anisotropic hydrodynamic function, similar to its anisotropic structure factor. This observation is important in order to guide future theoretical research.

  12. Reorientational dynamics of water confined in zeolites. (United States)

    Fogarty, Aoife C; Coudert, François-Xavier; Boutin, Anne; Laage, Damien


    We present a detailed molecular-dynamics study of water reorientation and hydrogen-bond dynamics in a strong confinement situation, within the narrow pores of an all-silica Linde type A (LTA) zeolite. Two water loadings of the zeolite are compared with the bulk case. Water dynamics are retarded in this extreme hydrophobic confinement and the slowdown is more pronounced at higher water loading. We show that water reorientation proceeds mainly by large-amplitude angular jumps, whose mechanism is similar to that determined in the bulk. The slowdown upon hydrophobic confinement arises predominantly from an excluded-volume effect on the large fraction of water molecules lying at the interface with the zeolite matrix, with an additional minor contribution coming from a structuring effect induced by the confinement. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Group Velocity Engineering of Confined Ultrafast Magnons (United States)

    Chen, Y.-J.; Zakeri, Kh.; Ernst, A.; Qin, H. J.; Meng, Y.; Kirschner, J.


    Quantum confinement permits the existence of multiple terahertz magnon modes in atomically engineered ultrathin magnetic films and multilayers. By means of spin-polarized high-resolution electron energy-loss spectroscopy, we report on the direct experimental detection of all exchange-dominated terahertz confined magnon modes in a 3 ML Co film. We demonstrate that, by tuning the structural and magnetic properties of the Co film, through its epitaxial growth on different surfaces, e.g., Ir(001), Cu(001), and Pt(111), one can achieve entirely different in-plane magnon dispersions, characterized by positive and negative group velocities. Our first-principles calculations show that spin-dependent many-body correlation effects in Co films play an important role in the determination of the energies of confined magnon modes. Our results suggest a pathway towards the engineering of the group velocity of confined ultrafast magnons.

  14. Frost damage of concrete subject to confinement

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange


    When internal frost damage is observed in real concrete structures, the usual pattern is cracks with a preferred orientation parallel to the exposed surface. When exposing concrete with poor frost resistance to a standardised freeze/thaw test in the laboratory, the orientations of the resulting...... cracks are more or less random. The present study is an experimental study, which aims at investigating the influence of confinement during freeze/thaw action on the developed crack pattern. Confinement is established by mounting hose clamps on cylindrical test specimens, using similar test specimens...... without hose clamps as reference. The results show that confinement can change the outcome of a freeze/thaw test as regards extent of internal cracking, crack orientations, and amount of surface scaling. Thus it seems likely that the difference in confinement (and therefore also in stress state) can...

  15. Monte Carlo simulations of confined polymer systems

    NARCIS (Netherlands)

    Vliet, Johannes Henricus van


    This thesis considers confined polymer systems. These systems are of considerable interest, e.g., thin polymer films, chromotography of polymer solutions, drag reduction, enhanced oil recovery, stabilization of colloidal dispersions, lubrication and biolubrication. The method used to study these

  16. Atmospheric Water-Cycle Regimes and Cloud Regimes (United States)

    Wong, S.; Fetzer, E. J.; L'Ecuyer, T. S.


    The relationship between the atmospheric water vapor budget and cloud properties is investigated by collocated reanalysis fields from Modern Era Retrospective-analysis for Research and Applications (MERRA) and the observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument. Intensities of surface water exchange (precipitation minus evaporation) are analyzed in the space of 'dynamical regimes', which are defined by combination of large-scale water vapor advection and convergence calculated from the MERRA. The atmospheric water vapor sinks associated with mid-latitude storm systems and precipitation in the west coast of United States are mainly driven by the large-scale dynamical advection, while those associated with tropical deep convection and summertime monsoons are mainly driven by water vapor convergence. Subtropical subsidence area over the eastern ocean basins is dominated by strong water vapor divergence. These dynamical regimes are then connected to the collocated MODIS cloud top pressure and cloud optical thickness. Probability density distributions of these MODIS cloud properties associated with each dynamical regime will be presented.

  17. Confined Space Evaluation Student Manual, #19613

    Energy Technology Data Exchange (ETDEWEB)

    Wilmot, David Ezekiel [Los Alamos National Laboratory


    Many workplaces contain spaces that are considered to be “confined” because their configuration hinders the activities of employees who must enter into, work in, and exit from them. In general, the permit-required confined spaces (PRCSs) Occupational Safety and Health Administration (OSHA) standard requires that Los Alamos National Laboratory (LANL) evaluate the workplace to determine if any spaces are PRCSs. The standard specifies strict procedures for the evaluation and atmospheric testing of a space before and during an entry by workers. The OSHA PRCS standard provides for alternative (less stringent than full-permit) entry procedures in cases where the only hazard in a space is atmospheric and the hazard can be controlled by forced air. At LANL, all confined spaces or potential confined spaces on LANL-owned or -operated property must be identified and evaluated by a confined space evaluator accompanied by a knowledgeable person. This course provides the information needed by confined space evaluators to make judgements about whether a space is a confined space, and if so, whether the space will require a permit for entry.

  18. Methods for two-dimensional cell confinement. (United States)

    Le Berre, Maël; Zlotek-Zlotkiewicz, Ewa; Bonazzi, Daria; Lautenschlaeger, Franziska; Piel, Matthieu


    Protocols described in this chapter relate to a method to dynamically confine cells in two dimensions with various microenvironments. It can be used to impose on cells a given height, with an accuracy of less than 100 nm on large surfaces (cm(2)). The method is based on the gentle application of a modified glass coverslip onto a standard cell culture. Depending on the preparation, this confinement slide can impose on the cells a given geometry but also an environment of controlled stiffness, controlled adhesion, or a more complex environment. An advantage is that the method is compatible with most optical microscopy technologies and molecular biology protocols allowing advanced analysis of confined cells. In this chapter, we first explain the principle and issues of using these slides to confine cells in a controlled geometry and describe their fabrication. Finally, we discuss how the nature of the confinement slide can vary and provide an alternative method to confine cells with gels of controlled rigidity. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Brazil and Mexico in the Nonproliferation Regime, Common Structures and Divergent Trajectories in Latin America


    Sotomayor, Arturo C.


    Chapter 8 There are multiple options Latin American countries to support and comply with the nuclear nonproliferation regime. At the global level, states can decide to ratify the core treaties and join their supporting institutions such as the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the International Atomic Energy Agency (IAEA), the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the Nuclear Suppliers Group (NSG), the Missile Technology Control Regime, the...

  20. Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures (United States)

    Fleming, Robert A.; Goss, Josue A.; Zou, Min


    The nanoindentation behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), horizontally-aligned Al/a-Si core-shell nanorods (CSRs) with various lengths, and an Al/a-Si layered thin film has been studied to understand the effects of geometrical confinement of the Al core on the CSN deformation behavior. When loaded beyond the elastic limit, the CSNs have an unconventional load-displacement behavior with no residual displacement after unloading, resulting in no net shape change after indentation. This behavior is enabled by dislocation activities within the confined Al core, as indicated by discontinuous indentation signatures (load-drops and load-jumps) observed in the load-displacement data. When the geometrical confinement of the core is slightly reduced, as in the case of CSRs with the shortest rod length, the discontinuous indentation signatures and deformation resistance are heavily reduced. Further decreases in core confinement result in conventional nanoindentation behavior, regardless of geometry. Supporting molecular dynamics simulations show that dislocations nucleated in the core of a CSN are more effectively removed during unloading compared to CSRs, which supports the hypothesis that the unique deformation resistance of Al/a-Si CSNs are enabled by 3-dimensional confinement of the Al core.

  1. Metal - Silicate Separation in a Deformation Regime: Implications for Early Differentiation Processes (United States)

    Rushmer, T.; Jones, J. H.; Gaetani, G.; Zanda, B.


    The segregation of metallic cores from silicate mantles is one of the earliest, and most important, differentiation process involved in the evolution of the Earth and other terrestrial planetary bodies. The physical segregation of Fe-rich metal from silicate imparted a strong geochemical signature on early silicate mantles due to the preferential incorporation of siderophile elements into the core. Reconciling our estimates of primary bulk silicate mantle with candidate planetary bulk compositions requires an understanding of the geochemical consequences of the different regimes in which core forming material may have been mobile. This includes not only the possible differentiation processes that occurred in the terrestrial planets, but also understanding the differentiation processes in the meteorite parent bodies. Although a magma ocean model is possible for efficient core formation, some scenarios call for segregation of the core from solid silicate and the geochemical consequences can be significantly different. Experimental studies are one way in which insight can be gained into the possible geochemical signatures of metal-silicate segregation. Deformation experiments in addition provide a dynamic component, which allows liquid metal to segregate from solid silicate. Starting materials are cored from a slab of the Kernouve fall which is composed of olivine, pyroxene, plagioclase, chromite and chlorapatite; Fe-Ni metal and sulfide form 20-25% of the sample. Experimental conditions are 1.0-1.4 GPa confining pressure with strain rates of 10-4/s to 10-6/s. Temperatures ranging from 900° C to 1050° C produce variable amounts of silicate melt and different mechanisms of metal segregation are observed. In experiments which are below the silicate solidus, mobility of FeS is extensive and deformation textures are cataclastic. Geochemical analyses shows that migration of Fe-S-Ni-O metal through fractures and along grain boundaries produces extensive modification to

  2. Detecting spatial regimes in ecosystems (United States)

    Sundstrom, Shana M.; Eason, Tarsha; Nelson, R. John; Angeler, David G.; Barichievy, Chris; Garmestani, Ahjond S.; Graham, Nicholas A.J.; Granholm, Dean; Gunderson, Lance; Knutson, Melinda; Nash, Kirsty L.; Spanbauer, Trisha; Stow, Craig A.; Allen, Craig R.


    Research on early warning indicators has generally focused on assessing temporal transitions with limited application of these methods to detecting spatial regimes. Traditional spatial boundary detection procedures that result in ecoregion maps are typically based on ecological potential (i.e. potential vegetation), and often fail to account for ongoing changes due to stressors such as land use change and climate change and their effects on plant and animal communities. We use Fisher information, an information theory-based method, on both terrestrial and aquatic animal data (U.S. Breeding Bird Survey and marine zooplankton) to identify ecological boundaries, and compare our results to traditional early warning indicators, conventional ecoregion maps and multivariate analyses such as nMDS and cluster analysis. We successfully detected spatial regimes and transitions in both terrestrial and aquatic systems using Fisher information. Furthermore, Fisher information provided explicit spatial information about community change that is absent from other multivariate approaches. Our results suggest that defining spatial regimes based on animal communities may better reflect ecological reality than do traditional ecoregion maps, especially in our current era of rapid and unpredictable ecological change.

  3. The Texas Experimental Tokamak: A plasma research facility. A proposal submitted to the Department of Energy in response to Program Notice 95-10: Innovations in toroidal magnetic confinement systems

    Energy Technology Data Exchange (ETDEWEB)



    The Fusion Research Center (FRC) at the University Texas will operate the tokamak TEXT-U and its associated systems for experimental research in basic plasma physics. While the tokamak is not innovative, the research program, diagnostics and planned experiments are. The fusion community will reap the benefits of the success in completing the upgrades (auxiliary heating, divertor, diagnostics, wall conditioning), developing diverted discharges in both double and single null configurations, exploring improved confinement regimes including a limiter H-mode, and developing unique, critical turbulence diagnostics. With these new regimes, the authors are poised to perform the sort of turbulence and transport studies for which the TEXT group has distinguished itself and for which the upgrade was intended. TEXT-U is also a facility for collaborators to perform innovative experiments and develop diagnostics before transferring them to larger machines. The general philosophy is that the understanding of plasma physics must be part of any intelligent fusion program, and that basic experimental research is the most important part of any such program. The emphasis of the proposed research is to provide well-documented plasmas which will be used to suggest and evaluate theories, to explore control techniques, to develop advanced diagnostics and analysis techniques, and to extend current drive techniques. Up to 1 MW of electron cyclotron heating (ECH) will be used not only for heating but as a localized, perturbative tool. Areas of proposed research are: (1) core turbulence and transport; (2) edge turbulence and transport; (3) turbulence analysis; (4) improved confinement; (5) ECH physics; (6) Alfven wave current drive; and (7) diagnostic development.

  4. Computational Support for Alternative Confinement Concepts Basic Plasma Science

    Energy Technology Data Exchange (ETDEWEB)

    Dalton D. Schnack


    within the radius for perfectly conducting wall stabilization of these modes. In this work we consider cases with up to two resistive walls. Moreover the feedback system is assumed to react to any given Fourier harmonic with an ideal response, in the sense that no spurious harmonics are generated. Successful feedback schemes are shown to be possible. However, a careful choice of the gains, along with the simultaneous feedback on at least 4 or 5 modes, is found to be necessary. (3) Studies of a stable rampdown operating regime for the RFP were performed in collaboration with Los Alamos National Laboratory and the University of Wisconsin. It was found that completely stable mean profiles can be obtained by properly tailoring the decaying time dependence of the toroidal current and magnetic flux. Deviations from optimal decay rates were shown to lead to single helicity (SH) and quasi-single helicity (QSH) states. In all cases the prospects for improved confinement properties were obtained. These results may account for the experimental observation of QSH states when the toroidal current is allowed to decay.

  5. Characterization of enhanced D{alpha} high-confinement modes in Alcator {ital C}-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Greenwald, M.; Boivin, R.; Bonoli, P.; Budny, R.; Fiore, C.; Goetz, J.; Granetz, R.; Hubbard, A.; Hutchinson, I.; Irby, J.; LaBombard, B.; Lin, Y.; Lipschultz, B.; Marmar, E.; Mazurenko, A.; Mossessian, D.; Sunn Pedersen, T.; Pitcher, C.S.; Porkolab, M.; Rice, J.; Rowan, W.; Snipes, J.; Schilling, G.; Takase, Y.; Terry, J.; Wolfe, S.; Weaver, J.; Welch, B.; Wukitch, S. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)


    Regimes of high-confinement mode have been studied in the Alcator {ital C}-Mod tokamak [Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)]. Plasmas with no edge localized modes (ELM-free) have been compared in detail to a new regime, enhanced D{alpha} (EDA). EDA discharges have only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus EDA discharges do not accumulate impurities and typically have a lower fraction of radiated power. The edge gradients in EDA seem to be relaxed by a continuous process rather than an intermittent one as is the case for standard ELMy discharges and thus do not present the first wall with large periodic heat loads. This process is probably related to fluctuations seen in the plasma edge. EDA plasmas are more likely at low plasma current (q{gt}3.7), for moderate plasma shaping, (triangularity {approximately}0.35{endash}0.55), and for high neutral pressures. As observed in soft x-ray emission, the pedestal width is found to scale with the same parameters that determine the EDA/ELM-free boundary. {copyright} {ital 1999 American Institute of Physics.}

  6. Integrated diagnostic analysis of inertial confinement fusion capsule performancea) (United States)

    Cerjan, Charles; Springer, Paul T.; Sepke, Scott M.


    A conceptual model is developed for typical inertial confinement fusion implosion conditions that integrates available diagnostic information to determine the stagnation properties of the interior fill and surrounding shell. Assuming pressure equilibrium at peak compression and invoking radiative and equation-of-state relations, the pressure, density, and electron temperature are obtained by optimized fitting of the experimental output to smooth, global functional forms. Typical observational data that may be used includes x-ray self-emission, directional neutron time-of-flight signals, neutron yield, high-resolution x-ray spectra, and radiographic images. This approach has been validated by comparison with radiation-hydrodynamic simulations, producing semi-quantitative agreement. Model results implicate poor kinetic energy coupling to the hot core as the primary cause of the observed low thermonuclear burn yields.

  7. Radiofrequency-heated enhanced confinement modes in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Y.; Boivin, R.L.; Bombarda, F.; Bonoli, P.T.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.A.; Golovato, S.N.; Granetz, R.; Greenwald, M.; Horne, S.F.; Hubbard, A.; Hutchinson, I.H.; Irby, J.; LaBombard, B.; Lipschultz, B.; Marmar, E.; May, M.; Mazurenko, A.; McCracken, G.; OShea, P.; Porkolab, M.; Reardon, J.; Rice, J.; Rost, C.; Schachter, J.; Snipes, J.A.; Stek, P.; Terry, J.; Watterson, R.; Welch, B.; Wolfe, S. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    Enhanced confinement modes up to a toroidal field of B{sub T}=8T have been studied with up to 3.5 MW of radiofrequency (rf) heating power in the ion cyclotron range of frequencies (ICRF) at 80 MHz. H-mode is observed when the edge temperature exceeds a threshold value. The high confinement mode (H-mode) with higher confinement enhancement factors (H) and longer duration became possible after boronization by reducing the radiated power from the main plasma. A quasi-steady state with high confinement (H=2.0), high normalized beta ({beta}{sub N}=1.5), low radiated power fraction (P{sub rad}{sup main}/P{sub loss}=0.3), and low effective charge (Z{sub eff}=1.5) has been obtained in Enhanced D{sub {alpha}} H-mode. This type of H-mode has enhanced levels of continuous D{sub {alpha}} emission and very little or no edge localized mode (ELM) activity, and reduced core particle confinement time relative to ELM-free H-mode. The pellet enhanced performance (PEP) mode is obtained by combining core fueling with pellet injection and core heating. A highly peaked pressure profile with a central value of 8 atmospheres was observed. The steep pressure gradient drives off-axis bootstrap current, resulting in a shear reversed safety factor (q) profile. Suppression of sawteeth appears to be important in maintaining the highly peaked pressure profile. Lithium pellets were found to be more effective than deuterium pellets in raising q{sub 0}. {copyright} {ital 1997 American Institute of Physics.}

  8. Evidence for confinement induced phase separation in ethanol–water mixture: a positron annihilation study (United States)

    Muthulakshmi, T.; Dutta, D.; Maheshwari, Priya; Pujari, P. K.


    We report an experimental evidence for the phase separation of ethanol–water mixture confined in mesoporous silica with different pore size using positron annihilation lifetime spectroscopy (PALS). A bulk-like liquid in the core of the pore and a distinct interfacial region near the pore surface have been identified based on ortho-positronium lifetime components. The lifetime corresponding to the core liquid shows similar behavior to the bulk liquid mixture while the interfacial lifetime shows an abrupt rise within a particular range of ethanol concentration depending on the pore size. This abrupt increase is attributed to the appearance of excess free-volume near the interfacial region. The excess free-volume is originated due to microphase separation of confined ethanol–water primarily at the vicinity of the pore wall. We envisage that probing free-volume changes at the interface using PALS is a sensitive way to investigate microphase separation under nanoconfinement.

  9. Effects of polydispersity on confined homopolymer melts: A Monte Carlo study (United States)

    Rorrer, Nicholas A.; Dorgan, John R.


    out the transitions between different scaling regimes. The overall picture that emerges is not unexpected - polydispersity profoundly affects the behavior of confined homopolymers.

  10. Confined catalysis under two-dimensional materials (United States)

    Li, Haobo; Xiao, Jianping; Bao, Xinhe


    Confined microenvironments formed in heterogeneous catalysts have recently been recognized as equally important as catalytically active sites. Understanding the fundamentals of confined catalysis has become an important topic in heterogeneous catalysis. Well-defined 2D space between a catalyst surface and a 2D material overlayer provides an ideal microenvironment to explore the confined catalysis experimentally and theoretically. Using density functional theory calculations, we reveal that adsorption of atoms and molecules on a Pt(111) surface always has been weakened under monolayer graphene, which is attributed to the geometric constraint and confinement field in the 2D space between the graphene overlayer and the Pt(111) surface. A similar result has been found on Pt(110) and Pt(100) surfaces covered with graphene. The microenvironment created by coating a catalyst surface with 2D material overlayer can be used to modulate surface reactivity, which has been illustrated by optimizing oxygen reduction reaction activity on Pt(111) covered by various 2D materials. We demonstrate a concept of confined catalysis under 2D cover based on a weak van der Waals interaction between 2D material overlayers and underlying catalyst surfaces. PMID:28533413

  11. Stiffness and Confinement Ratios of SMA Wire Jackets for Confining Concrete (United States)

    Choi, Eunsoo; Kim, Dong Joo; Youn, Heejung


    This article discusses the effects of the stiffness and confinement ratios of shape memory alloy (SMA) wire jackets on the behavior of confined concrete. SMA wire jackets are an effective confining material to improve concrete behavior; for example, by increasing peak strength and failure strain. The stiffness and confinement ratios of fiber-reinforced polymer jackets have been extensively discussed and their effects are well known. However, assessment of the stiffness and confinement ratios of SMA wire jackets has not previously been conducted. In this study, we investigate the effects of the stiffness and confinement ratios of steel jackets, and then compare the results with those of SMA wire jackets. In general, the stiffness ratios of SMA wire jackets are relatively smaller than those of steel jackets, and most of them have lower stiffness ratios because the Young's moduli of the SMAs are relatively small. The active confining pressure of the SMA wires does not improve the lower stiffness-ratio effect since the amount of active confining pressure is not sufficiently large.

  12. Phase separation of weakly incompatible polymer blends confined in isolated droplets

    CERN Document Server

    Müller-Buschbaum, P; Cubitt, R


    Phase separation of the weakly incompatible blend system polystyrene and polyparamethylstyrene confined in isolated droplets is investigated. The droplet geometry imposes a two-dimensional spatial restriction. With specular, diffuse and grazing incidence small-angle neutron scattering the surface topography as well as the chemical morphology inside the droplets is determined. Due to the differences in surface tension, a core-shell-like structure characterized by one most prominent length scale inside the droplets is installed. (orig.)

  13. Implementation Regimes and Street-Level Bureaucrats

    DEFF Research Database (Denmark)

    Winter, Søren; T. Dinesen, Peter; J. May, Peter

    -government regimes foster greater policy commitment, attention to rules, and adherence among frontline workers than is the case for a local-government implementation regime. These lead to actions of street-level bureaucrats in central-government regimes that are more in line with national policies than those...

  14. The Two Regimes of Postwar Shipping

    DEFF Research Database (Denmark)

    Iversen, Martin Jes; Tenold, Stig


    the bargaining that accompanied the shift from the national regime to the competitive regime. Specifically, we show that the new regime primarily accommodated the interests of private actors such as shipping companies, rather than the interests of the authorities and the trade unions....

  15. Structural and dynamic properties of confined water in nanometric model porous materials (8 A{<=}diameter{<=}40 A)

    Energy Technology Data Exchange (ETDEWEB)

    Floquet, N.; Coulomb, J.P.; Dufau, N.; Andre, G.; Kahn, R


    Structural and dynamic properties of confined water have been investigated by 'in situ' neutron-scattering experiments. In the medium confinement regime (for MCM-41 host materials: 20 A{<=}diameter{<=}40 A) confined water has rather similar properties to bulk (3d) water. The major difference concerns the solidification phase transition. Strong triple-point depression {delta}T{sub 3t} is observed and {delta}T{sub 3t} increases when decreasing the pore diameter (213 K{<=}{delta}T{sub 3t}{<=}233 K). Such a confined water behaves as a supercooled liquid phase. The ultra-confinement (AlPO{sub 4}-N zeolites: 8 A{<=}diameter{<=}12 A), is seen to induce the structuration of the confined water and its stability at room temperature T=300 K due to commensurability effect with the AlPO{sub 4}-5 inner surface. No wetting phenomena are observed for both host materials, the silicic MCM-41 samples and the AlPO{sub 4}-N zeolite family.

  16. Structural and dynamic properties of confined water in nanometric model porous materials (8 Å⩽∅⩽40 Å) (United States)

    Floquet, N.; Coulomb, J. P.; Dufau, N.; Andre, G.; Kahn, R.


    Structural and dynamic properties of confined water have been investigated by ‘‘in situ’’ neutron-scattering experiments. In the medium confinement regime (for MCM-41 host materials: 20 Å⩽∅⩽40 Å) confined water has rather similar properties to bulk (3d) water. The major difference concerns the solidification phase transition. Strong triple-point depression Δ T3t is observed and Δ T3t increases when decreasing the pore diameter ∅ (213 K⩽Δ T3t⩽233 K). Such a confined water behaves as a supercooled liquid phase. The ultra-confinement (AlPO 4-N zeolites: 8 Å⩽∅⩽12 Å), is seen to induce the structuration of the confined water and its stability at room temperature T=300 K due to commensurability effect with the AlPO 4-5 inner surface. No wetting phenomena are observed for both host materials, the silicic MCM-41 samples and the AlPO 4-N zeolite family.

  17. Jet characteristics in confined swirling flow (United States)

    So, R. M. C.; Ahmed, S. A.; Mongia, H. C.


    Jets in confined swirling flow are investigated in a facility where the swirling flow in the tube is produced by a vane-type swirler. The jet is located centrally in the swirler, and the diameter ratio of the tube to the jet is about 14. Both the jet and the swirling flow are fully turbulent. Results show that the confined jet is highly dissipative in nature. Consequently, the flow in the tube does not resemble a free jet with axial pressure gradient. The presence of swirl increases the rate of dissipation and the jet decays even faster. A fairly isotropic turbulence field is observed in the confined swirling flow. However, the introduction of the jet does not significantly affect this behavior, and near isotropy of the turbulence field is again observed at about 30 jet diameters downstream.

  18. Confined space facilitates G-quadruplex formation (United States)

    Shrestha, Prakash; Jonchhe, Sagun; Emura, Tomoko; Hidaka, Kumi; Endo, Masayuki; Sugiyama, Hiroshi; Mao, Hanbin


    Molecular simulations suggest that the stability of a folded macromolecule increases in a confined space due to entropic effects. However, due to the interactions between the confined molecular structure and the walls of the container, clear-cut experimental evidence for this prediction is lacking. Here, using DNA origami nanocages, we show the pure effect of confined space on the property of individual human telomeric DNA G-quadruplexes. We induce targeted mechanical unfolding of the G-quadruplex while leaving the nanocage unperturbed. We find that the mechanical and thermodynamic stabilities of the G-quadruplex inside the nanocage increase with decreasing cage size. Compared to the case of diluted or molecularly crowded buffer solutions, the G-quadruplex inside the nanocage is significantly more stable, showing a 100 times faster folding rate. Our findings suggest the possibility of co-replicational or co-transcriptional folding of G-quadruplex inside the polymerase machinery in cells.

  19. Transition metal catalysis in confined spaces. (United States)

    Leenders, Stefan H A M; Gramage-Doria, Rafael; de Bruin, Bas; Reek, Joost N H


    Transition metal catalysis plays an important role in both industry and in academia where selectivity, activity and stability are crucial parameters to control. Next to changing the structure of the ligand, introducing a confined space as a second coordination sphere around a metal catalyst has recently been shown to be a viable method to induce new selectivity and activity in transition metal catalysis. In this review we focus on supramolecular strategies to encapsulate transition metal complexes with the aim of controlling the selectivity via the second coordination sphere. As we will discuss, catalyst confinement can result in selective processes that are impossible or difficult to achieve by traditional methods. We will describe the template-ligand approach as well as the host-guest approach to arrive at such supramolecular systems and discuss how the performance of the catalyst is enhanced by confining it in a molecular container.

  20. Density shock waves in confined microswimmers

    CERN Document Server

    Tsang, Alan Cheng Hou


    Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from `subsonic' with compression at the back to `supersonic' with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a non-trivial interplay between hydrodynamic interactions and geometric confinement, and is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechan...

  1. Dual hollow-core anti-resonant fibres (United States)

    Wheeler, N. V.; Bradley, T. D.; Hayes, J. R.; Jasion, G. T.; Chen, Y.; Sandoghchi, S. R.; Horak, P.; Poletti, F.; Petrovich, M. N.; Richardson, D. J.


    While hollow core-photonic crystal fibres are now a well-established fibre technology, the majority of work on these speciality fibres has been on designs with a single core for optical guidance. In this paper we present the first dual hollow-core anti-resonant fibres (DHC-ARFs). The fibres have high structural uniformity and low loss (minimum loss of 0.5 dB/m in the low loss guidance window) and demonstrate regimes of both inter-core coupling and zero coupling, dependent on the wavelength of operation, input polarisation, core separation and bend radius. In a DHC-ARF with a core separation of 4.3 μm, we find that with an optimised input polarisation up to 65% of the light guided in the launch core can be coupled into the second core, opening up applications in power delivery, gas sensing and quantum optics.

  2. A stationary long-pulse ELM-absent H-mode regime in EAST (United States)

    Ye, Y.; Xu, G. S.; Wan, B. N.; Chen, R.; Yan, N.; Guo, H. Y.; Shao, L. M.; Yang, Q. Q.; Wang, H. Q.; Zhang, W.; Xia, T. Y.; Zhang, T.; Li, Y. Y.; Wang, T. F.; Zang, Q.; Hu, Y. J.; Wu, G. J.; Zhang, L.; Hao, B. L.; Wang, L.; Li, Y. L.; Wu, X. Q.; Chen, L.; Lan, H.; Wang, Y. F.; Xu, J. C.; Hu, G. H.; Ding, S. Y.; Zhang, H.; Zhao, N.; Li, J.; The EAST Team


    A stationary edge-localized mode (ELM)-absent H-mode regime, with an electrostatic edge coherent mode (ECM) which resides in the pedestal region, has been achieved in the EAST tokamak recently. This regime allows the operation of a nearly fully noninductive long pulse (>15 s), exhibiting a relatively high pedestal and good global energy confinement with {{H}98,y2} near 1.2, and excellent impurity control. Furthermore, this regime is mostly obtained with a 4.6 GHz lower hybrid current drive (LHCD) or counter-current neutral beam injection (NBI), plus electron cyclotron resonance heating, and an extensive lithium wall coating. This stationary ELM-absent H-mode regime transits to a stationary small ELM H-mode regime, and upon additional heating power from the 2.45 GHz LHCD, an ion cyclotron resonant frequency or co-current NBI is applied (under 4.6 GHz LHCD heating background). A slight change of the plasma configuration also makes the small ELMs reappear. The experimental observations suggest that a long-pulse ELM-absent regime can be induced by the ECM, which exhibits strong electrostatic fluctuations and may provide a channel for continuous particle (especially impurities) and heat exhaust across the pedestal. The ECM exists in the collisionality of ν e*   =  2.5-4 and the pressure gradient |\

  3. High-field penning-malmberg trap: confinement properties and use in positron accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, J.H.


    This dissertation reports on the development of the 60 kG cryogenic positron trap at Lawrence Livermore National Laboratory, and compares the trap`s confinement properties with other nonneutral plasma devices. The device is designed for the accumulation of up to 2{times}10{sup 9} positrons from a linear-accelerator source. This positron plasma could then be used in Bhabha scattering experiments. Initial efforts at time-of-flight accumulation of positrons from the accelerator show rapid ({approximately}100 ms) deconfinement, inconsistent with the long electron lifetimes. Several possible deconfinement mechanisms have been explored, including annihilation on residual gas, injection heating, rf noise from the accelerator, magnet field curvature, and stray fields. Detailed studies of electron confinement demonstrate that the empirical scaling law used to design the trap cannot be extrapolated into the parameter regime of this device. Several possible methods for overcoming these limitations are presented.

  4. A new model of gluon confinement

    Energy Technology Data Exchange (ETDEWEB)

    Novello, M.; De Lorenci, V.A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Elbaz, E. [Universite Claude Bernard, 69 - Lyon (France). Inst. de Physique Nucleaire


    In this paper we present a model for the dynamics of a gauge field theory such that spin-one particles can be confined in a compact domain. We show that the property of confinement can be associated to the formation of a null surface identified to a horizon. This is due the presence of an effective geometry generated by the self-interaction of the gauge field that guides the wave propagation of the field. This phenomenon has a striking analog to the gravitational back hole in Einstein general theory of relativity, separating two domains of spacetime that can be trespassed only into one direction. (author) 4 refs., 1 fig.

  5. Molecular reactivity dynamics in a confined environment. (United States)

    Khatua, Munmun; Chattaraj, Pratim Kumar


    Time evolution of various reactivity parameters viz. hardness, electrophilicity, chemical potential, polarizability, etc. in a confined environment has been studied through quantum fluid density functional theory formalism during time dependent processes such as proton-molecule collisions and molecule-field interaction. A Dirichlet type boundary condition has been incorporated to confine the systems. Responses in the reactivity parameters of the diatomic molecules, in the dynamical context, in ground state as well as in excited state, have been reported. Harmonic spectra are generated in the cases of the external laser field interacting with H2 and N2 molecules.

  6. Measuring the effectiveness of international environmental regimes

    Energy Technology Data Exchange (ETDEWEB)

    Helm, C.; Sprinz, D.F.


    While past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes by developing an operational rational choice calculus to evaluate actual policy simultaneously against a non-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement instrument is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects - but fall substantially short of the collective optima. (orig.)

  7. Different regimes of dynamic wetting (United States)

    Gustav, Amberg; Wang, Jiayu; Do-Quang, Minh; Shiomi, Junichiro; Physiochemical fluid mechanics Team; Maruyama-Chiashi Laboratory Team


    Dynamic wetting, as observed when a droplet contacts a dry solid surface, is important in various engineering processes, such as printing, coating, and lubrication. Our overall aim is to investigate if and how the detailed properties of the solid surface influence the dynamics of wetting. Here we discuss how surface roughness influences the initial dynamic spreading of a partially wetting droplet by studying the spreading on a solid substrate patterned with microstructures just a few micrometers in size. This is complemented by matching numerical simulations. We present a parameter map, based on the properties of the liquid and the solid surface, which identifies qualitatively different spreading regimes, where the spreading speed is limited by either the liquid viscosity, the surface properties, or the liquid inertia. The peculiarities of the different spreading regimes are studied by detailed numerical simulations, in conjuction with experiments. This work was financially supported in part by, the Japan Society for the Promotion of Science (J.W. and J.S) and Swedish Governmental Agency for Innovation Systems (M.D.-Q. and G.A).

  8. Adaptation in Collaborative Governance Regimes (United States)

    Emerson, Kirk; Gerlak, Andrea K.


    Adaptation and the adaptive capacity of human and environmental systems have been of central concern to natural and social science scholars, many of whom characterize and promote the need for collaborative cross-boundary systems that are seen as flexible and adaptive by definition. Researchers who study collaborative governance systems in the public administration, planning and policy literature have paid less attention to adaptive capacity specifically and institutional adaptation in general. This paper bridges the two literatures and finds four common dimensions of capacity, including structural arrangements, leadership, knowledge and learning, and resources. In this paper, we focus on institutional adaptation in the context of collaborative governance regimes and try to clarify and distinguish collaborative capacity from adaptive capacity and their contributions to adaptive action. We posit further that collaborative capacities generate associated adaptive capacities thereby enabling institutional adaptation within collaborative governance regimes. We develop these distinctions and linkages between collaborative and adaptive capacities with the help of an illustrative case study in watershed management within the National Estuary Program.

  9. Fabrication of silica hollow core photonic crystal fibres for Er:YAG surgical applications (United States)

    Urich, Artur; Maier, Robert R. J.; Knight, Jonathan C.; Mangan, Brian J.; Renshaw, Steven; Hand, Duncan P.; Shephard, Jonathan D.


    In this work we present the fabrication of silica hollow core photonic crystal fibres (HC-PCF) with guidance at 2.94μm. As light is confined inside the hollow core with a very small overlap of the guided E-M wave with the fibre material, the high intrinsic loss of silica at these mid-infrared wavelengths can be overcome. The band gap effect is achieved by a periodic structure made out of air and fused silica. As silica is bio-inert, chemically stable and mechanically robust, these fibres have potential advantages over other multi-component, non-silica optical fibres designed to guide in this wavelength regime. These fibres have a relatively small diameter, low bend sensitivity and single-mode like guidance which are ideal conditions for delivering laser light down a highly flexible fibre. Consequently they provide a potential alternative to existing surgical laser delivery methods such as articulated arms and lend themselves to endoscopy and other minimally invasive surgical procedures. In particular, we present the characterisation and performance of these fibres at 2.94 μm, the wavelength of an Er:YAG laser. This laser is widely used in surgery since the wavelength overlaps with an absorption band of water which results in clean, non-cauterised cuts. However, the practical implementation of these types of fibres for surgical applications is a significant challenge. Therefore we also report on progress made in developing hermetically sealed end tips for these hollow core fibres to avoid contamination. This work ultimately prepares the route towards a robust, practical delivery system for this wavelength.

  10. Transition between two regimes describing internal fluctuation of DNA in a nanochannel.

    Directory of Open Access Journals (Sweden)

    Tianxiang Su

    Full Text Available We measure the thermal fluctuation of the internal segments of a piece of DNA confined in a nanochannel about 50-100 nm wide. This local thermodynamic property is key to accurate measurement of distances in genomic analysis. For DNA in ~100 nm channels, we observe a critical length scale ~10 m for the mean extension of internal segments, below which the de Gennes' theory describes the fluctuations with no fitting parameters, and above which the fluctuation data falls into Odijk's deflection theory regime. By analyzing the probability distributions of the extensions of the internal segments, we infer that folded structures of length 150-250 nm, separated by ~10 m exist in the confined DNA during the transition between the two regimes. For ~50 nm channels we find that the fluctuation is significantly reduced since the Odijk regime appears earlier. This is critical for genomic analysis. We further propose a more detailed theory based on small fluctuations and incorporating the effects of confinement to explicitly calculate the statistical properties of the internal fluctuations. Our theory is applicable to polymers with heterogeneous mechanical properties confined in non-uniform channels. We show that existing theories for the end-to-end extension/fluctuation of polymers can be used to study the internal fluctuations only when the contour length of the polymer is many times larger than its persistence length. Finally, our results suggest that introducing nicks in the DNA will not change its fluctuation behavior when the nick density is below 1 nick per kbp DNA.

  11. Performance analysis of vortex based mixers for confined flows (United States)

    Buschhagen, Timo

    The hybrid rocket is still sparsely employed within major space or defense projects due to their relatively poor combustion efficiency and low fuel grain regression rate. Although hybrid rockets can claim advantages in safety, environmental and performance aspects against established solid and liquid propellant systems, the boundary layer combustion process and the diffusion based mixing within a hybrid rocket grain port leaves the core flow unmixed and limits the system performance. One principle used to enhance the mixing of gaseous flows is to induce streamwise vorticity. The counter-rotating vortex pair (CVP) mixer utilizes this principle and introduces two vortices into a confined flow, generating a stirring motion in order to transport near wall media towards the core and vice versa. Recent studies investigated the velocity field introduced by this type of swirler. The current work is evaluating the mixing performance of the CVP concept, by using an experimental setup to simulate an axial primary pipe flow with a radially entering secondary flow. Hereby the primary flow is altered by the CVP swirler unit. The resulting setup therefore emulates a hybrid rocket motor with a cylindrical single port grain. In order to evaluate the mixing performance the secondary flow concentration at the pipe assembly exit is measured, utilizing a pressure-sensitive paint based procedure.

  12. Nonlinear Plasma Response to Resonant Magnetic Perturbation in Rutherford Regime (United States)

    Zhu, Ping; Yan, Xingting; Huang, Wenlong


    Recently a common analytic relation for both the locked mode and the nonlinear plasma response in the Rutherford regime has been developed based on the steady-state solution to the coupled dynamic system of magnetic island evolution and torque balance equations. The analytic relation predicts the threshold and the island size for the full penetration of resonant magnetic perturbation (RMP). It also rigorously proves a screening effect of the equilibrium toroidal flow. In this work, we test the theory by solving for the nonlinear plasma response to a single-helicity RMP of a circular-shaped limiter tokamak equilibrium with a constant toroidal flow, using the initial-value, full MHD simulation code NIMROD. Time evolution of the parallel flow or ``slip frequency'' profile and its asymptotic approach to steady state obtained from the NIMROD simulations qualitatively agree with the theory predictions. Further comparisons are carried out for the saturated island size, the threshold for full mode penetration, as well as the screening effects of equilibrium toroidal flow in order to understand the physics of nonlinear plasma response in the Rutherford regime. Supported by National Magnetic Confinement Fusion Science Program of China Grants 2014GB124002 and 2015GB101004, the 100 Talent Program of the Chinese Academy of Sciences, and U.S. Department of Energy Grants DE-FG02-86ER53218 and DE-FC02-08ER54975.

  13. Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets (United States)

    Gauthier, P.; Chaland, F.; Masse, L.


    By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas.

  14. Confinement of light in a polarizable vacuum

    Directory of Open Access Journals (Sweden)

    Avinash Khare


    Full Text Available We show that an electrically polarizable vacuum with space-dependent permeability ε(r = μ−1(rexp(−αr2 can confine light whose quanta acquire a mass through interaction with this vacuum.

  15. Modulus-Pressure Equation for Confined Fluids

    CERN Document Server

    Gor, Gennady Y; Shen, Vincent K; Bernstein, Noam


    Ultrasonic experiments allow one to measure the elastic modulus of bulk solid or fluid samples. Recently such experiments have been carried out on fluid-saturated nanoporous glass to probe the modulus of a confined fluid. In our previous work [J. Chem. Phys., (2015) 143, 194506], using Monte Carlo simulations we showed that the elastic modulus $K$ of a fluid confined in a mesopore is a function of the pore size. Here we focus on modulus-pressure dependence $K(P)$, which is linear for bulk materials, a relation known as the Tait-Murnaghan equation. Using transition-matrix Monte Carlo simulations we calculated the elastic modulus of bulk argon as a function of pressure and argon confined in silica mesopores as a function of Laplace pressure. Our calculations show that while the elastic modulus is strongly affected by confinement and temperature, the slope of the modulus versus pressure is not. Moreover, the calculated slope is in a good agreement with the reference data for bulk argon and experimental data for ...

  16. Non-resonant Nanoscale Extreme Light Confinement

    Energy Technology Data Exchange (ETDEWEB)

    Subramania, Ganapathi Subramanian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Huber, Dale L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    A wide spectrum of photonics activities Sandia is engaged in such as solid state lighting, photovoltaics, infrared imaging and sensing, quantum sources, rely on nanoscale or ultrasubwavelength light-matter interactions (LMI). The fundamental understanding in confining electromagnetic power and enhancing electric fields into ever smaller volumes is key to creating next generation devices for these programs. The prevailing view is that a resonant interaction (e.g. in microcavities or surface-plasmon polaritions) is necessary to achieve the necessary light confinement for absorption or emission enhancement. Here we propose new paradigm that is non-resonant and therefore broadband and can achieve light confinement and field enhancement in extremely small areas [~(λ/500)^2 ]. The proposal is based on a theoretical work[1] performed at Sandia. The paradigm structure consists of a periodic arrangement of connected small and large rectangular slits etched into a metal film named double-groove (DG) structure. The degree of electric field enhancement and power confinement can be controlled by the geometry of the structure. The key operational principle is attributed to quasistatic response of the metal electrons to the incoming electromagnetic field that enables non-resonant broadband behavior. For this exploratory LDRD we have fabricated some test double groove structures to enable verification of quasistatic electronic response in the mid IR through IR optical spectroscopy. We have addressed some processing challenges in DG structure fabrication to enable future design of complex sensor and detector geometries that can utilize its non-resonant field enhancement capabilities.].

  17. Enhanced heat transfer in confined pool boiling

    NARCIS (Netherlands)

    Rops, C.M.; Lindken, R.; Velthuis, J.F.M.; Westerweel, J.


    We report the results of an experimental investigation of the heat transfer during nucleate boiling on a spatially confined boiling surface. The heat flux as a function of the boiling surface temperature was measured in pool boiling pots with diameters ranging from 15 mm down to 4.5 mm. It was found

  18. Mesoscale simulations of confined Nafion thin films (United States)

    Vanya, P.; Sharman, J.; Elliott, J. A.


    The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

  19. Subwavelength light confinement with surface plasmon polaritons

    NARCIS (Netherlands)

    Verhagen, E.


    In free space, the diffraction limit sets a lower bound to the size to which light can be confined. Surface plasmon polaritons (SPPs), which are electromagnetic waves bound to the interface between a metal and a dielectric, allow the control of light on subwavelength length scales. This opens up a

  20. Structure of polymer chains under confinement

    Indian Academy of Sciences (India)

    Abstract. We observe by SANS the structure of neutral polystyrene and charged polystyrene sulphonate chains in semi-dilute solutions confined in a model nanoporous glass, Vycor. The size of the free chains in solution is always larger than the pore di- ameter, 70. The use of a suitable mixture of hydrogenated and ...

  1. Analysis of thermally-degrading, confined HMX

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Schmitt, R.G.; Renlund, A.M.


    The response of a thermally-degrading, confined HMX pellet is analyzed using a Reactive Elastic-Plastic (REP) constitutive model which is founded on the collapse and growth of internal inclusions resulting from physical and chemical processes such as forced displacement, thermal expansion, and/or decomposition. Axial stress predictions compare adequately to data. Deficiencies in the model and future directions are discussed.

  2. Clusters of polyhedra in spherical confinement (United States)

    Teich, Erin G.; van Anders, Greg; Klotsa, Daphne; Dshemuchadse, Julia; Glotzer, Sharon C.


    Dense particle packing in a confining volume remains a rich, largely unexplored problem, despite applications in blood clotting, plasmonics, industrial packaging and transport, colloidal molecule design, and information storage. Here, we report densest found clusters of the Platonic solids in spherical confinement, for up to N=60 constituent polyhedral particles. We examine the interplay between anisotropic particle shape and isotropic 3D confinement. Densest clusters exhibit a wide variety of symmetry point groups and form in up to three layers at higher N. For many N values, icosahedra and dodecahedra form clusters that resemble sphere clusters. These common structures are layers of optimal spherical codes in most cases, a surprising fact given the significant faceting of the icosahedron and dodecahedron. We also investigate cluster density as a function of N for each particle shape. We find that, in contrast to what happens in bulk, polyhedra often pack less densely than spheres. We also find especially dense clusters at so-called magic numbers of constituent particles. Our results showcase the structural diversity and experimental utility of families of solutions to the packing in confinement problem. PMID:26811458

  3. Confined surface plasmons in gold photonic nanocavities

    Energy Technology Data Exchange (ETDEWEB)

    Netti, C.; Coyle, S.; Baumberg, J.J. [Southampton Univ. (United Kingdom). Dept. of Physics and Astronomy; Ghanem, M.A.; Birkin, P.R.; Bartlett, P.N. [Southampton Univ. (United Kingdom). Dept. of Chemistry; Whittaker, D.M. [Toshiba Research Europe Ltd., Cambridge (United Kingdom)


    A simple scheme to produce large-area colored metal surfaces by completely confining surface plasmons inside gold spherical nanocavities has been discovered. The negative nanocavity curvature localizes the electromagnetic fields into small volumes, which can be arranged non-periodically. (orig.)

  4. Spinal cord compression following traditional confinement massage. (United States)

    Sahathevan, R; Tan, H J; Abdullah, Suhail; Shahizon, A M M; Hamidon, B B; Raymond, A A


    We describe a case of tetraparesis in a 33-year-old woman following neck manipulation performed by a traditional confinement mid-wife. An MRI of the cervical spine revealed a fracture of the second cervical vertebra with atlanto-axial subluxation that resulted in cord compression.

  5. Capillary breakup of fluid threads within confinement (United States)

    Hu, Guoqing; Xue, Chundong; Chen, Xiaodong


    Fluid thread breakup is a widespread phenomenon in nature, industry, and daily life. Driven by surface tension (or capillarity) at low flow-rate condition, the breakup scenario is usually called capillary instability or Plateau-Rayleigh instability. Fluid thread deforms under confinement of ambient fluid to form a fluid neck. Thinning of the neck at low flow-rate condition is quasistatic until the interface becomes unstable and collapses to breakup. Underlying mechanisms and universalities of both the stable and unstable thinning remain, however, unclear and even contradictory. Here we conduct new numerical and experimental studies to show that confined interfaces are not only stabilized but also destabilized by capillarity at low flow-rate condition. Capillary stabilization is attributed to confinement-determined internal pressure that is higher than capillary pressure along the neck. Two origins of capillary destabilization are identified: one is confinement-induced gradient of capillary pressure along the interface; the other is the competition between local capillary pressure and internal pressure. This work was supported by National Natural Science Foundation of China (Grant No. 11402274, 11272321, and 11572334).

  6. Ultrafast chemistry in complex and confined systems

    Indian Academy of Sciences (India)

    Self-organized molecular assemblies play a crucial role in many natural and biological processes. Recent applications of ultrafast laser spectroscopy and computer simulations revealed that chemistry in a confined environment is fundamentally different from that in ordinary solutions. Many recent examples of slow dynamics ...

  7. Fire regime in Mediterranean ecosystem (United States)

    Biondi, Guido; Casula, Paolo; D'Andrea, Mirko; Fiorucci, Paolo


    The analysis of burnt areas time series in Mediterranean regions suggests that ecosystems characterising this area consist primarily of species highly vulnerable to the fire but highly resilient, as characterized by a significant regenerative capacity after the fire spreading. In a few years the area burnt may once again be covered by the same vegetation present before the fire. Similarly, Mediterranean conifer forests, which often refers to plantations made in order to reforest the areas most severely degraded with high erosion risk, regenerate from seed after the fire resulting in high resilience to the fire as well. Only rarely, and usually with negligible damages, fire affects the areas covered by climax species in relation with altitude and soil types (i.e, quercus, fagus, abies). On the basis of these results, this paper shows how the simple Drossel-Schwabl forest fire model is able to reproduce the forest fire regime in terms of number of fires and burned area, describing whit good accuracy the actual fire perimeters. The original Drossel-Schwabl model has been slightly modified in this work by introducing two parameters (probability of propagation and regrowth) specific for each different class of vegetation cover. Using model selection methods based on AIC, the model with the optimal number of classes with different fire behaviour was selected. Two different case studies are presented in this work: Regione Liguria and Regione Sardegna (Italy). Both regions are situated in the center of the Mediterranean and are characterized by a high number of fires and burned area. However, the two regions have very different fire regimes. Sardinia is affected by the fire phenomenon only in summer whilst Liguria is affected by fires also in winter, with higher number of fires and larger burned area. In addition, the two region are very different in vegetation cover. The presence of Mediterranean conifers, (Pinus Pinaster, Pinus Nigra, Pinus halepensis) is quite spread in

  8. Effects of high sound speed confiners on ANFO detonations (United States)

    Kiyanda, Charles; Jackson, Scott; Short, Mark


    The interaction between high explosive (HE) detonations and high sound speed confiners, where the confiner sound speed exceeds the HE's detonation speed, has not been thoroughly studied. The subsonic nature of the flow in the confiner allows stress waves to travel ahead of the main detonation front and influence the upstream HE state. The interaction between the detonation wave and the confiner is also no longer a local interaction, so that the confiner thickness now plays a significant role in the detonation dynamics. We report here on larger scale experiments in which a mixture of ammonium nitrate and fuel oil (ANFO) is detonated in aluminium confiners with varying charge diameter and confiner thickness. The results of these large-scale experiments are compared with previous large-scale ANFO experiments in cardboard, as well as smaller-scale aluminium confined ANFO experiments, to characterize the effects of confiner thickness.

  9. Free and confined jets at low Reynolds numbers (United States)

    Koller-Milojevie, Dušica; Schneider, Wilhelm


    Free jets, and jets with tubular confinements, are investigated in the jet Reynolds number regime 80 ⩽ Re j ⩽ 1000 being of interest for micro-jet pumps, among other applications. For issuing the jets, conventional (single-hole) nozzles as well as dual-hole nozzles of a particular design are used. Both flow visualization and LDA measurement indicate that, in agreement with previous findings, the jets issuing from conventional nozzles remain laminar up to large distances from the orifice. Thus there is but little entrainment of ambient fluid, and the performance of conventional nozzles in micro-jet pumps is rather poor. The dual-hole nozzles, on the other hand, are found to enforce transition to turbulent flow near the orifices. As a result, the entrainment rate is considerably increased, and the performance of jet pumps is improved when the dual-hole nozzles are applied. The experimental data are found to be in fair agreement with predictions based on mass and momentum balances.

  10. A Novel Low Loss, Highly Birefringent Photonic Crystal Fiber in THz Regime

    DEFF Research Database (Denmark)

    Hasanuzzaman, G. K. M.; Rana, Sohel; Habib, Selim


    We present a new kind of dual-hole unit-based porous-core hexagonal photonic crystal fiber (H-PCF) with low loss and high birefringence in terahertz regime. The proposed fiber offers simultaneously high birefringence and low effective material loss (EML) in the frequency range of 0.5-0.85 THz...

  11. Shock-induced kelyphite formation in the core of a complex impact crater (United States)

    Deseta, Natalie; Boonsue, Suporn; Gibson, Roger L.; Spray, John G.


    occurred as the shocked rock volume underwent post-shock expansion, forming the core of the central uplift, and was followed by variable textural re-equilibration. This study thus provides a microtextural and mineralogical perspective of the shock regime within confined crust immediately prior to and during central uplift formation.

  12. Nonlinear optics at the single-photon level inside a hollow core fiber

    DEFF Research Database (Denmark)

    Hofferberth, Sebastian; Peyronel, Thibault; Liang, Qiyu


    Cold atoms inside a hollow core fiber provide an unique system for studying optical nonlinearities at the few-photon level. Confinement of both atoms and photons inside the fiber core to a diameter of just a few wavelengths results in high electric field intensity per photon and large optical dep...

  13. Porous shaped photonic crystal fiber with strong confinement field in sensing applications: Design and analysis

    Directory of Open Access Journals (Sweden)

    Sawrab Chowdhury


    Full Text Available In this article, porous core porous cladding photonic crystal fiber (P-PCF has been proposed for aqueous analytes sensing applications. Guiding properties of the proposed P-PCF has been numerically investigated by utilizing the full vectorial finite element method (FEM. The relative sensitivity and confinement loss are obtained by varying distinct geometrical parameters like the diameter of air holes, a pitch of the core and cladding region over a wider range of wavelength. The proposed P-PCF is organized with five rings air hole in the cladding and two rings air hole in a core territory which maximizes the relative sensitivity expressively and minimizes confinement loss depressively compare with the prior-PCF structures. After completing all investigations, it is also visualized that the relative sensitivity is increasing with the increment of the wavelength of communication band (O + E + S + C + L + U. Higher sensitivity is gained by using higher band for all applied liquids. Finally the investigating effects of different structural parameters of the proposed P-PCF are optimized which shows the sensitivity of 60.57%, 61.45% and 61.82%; the confinement loss of 8.71 × 10−08 dB/m, 1.41 × 10−10 dB/m and 6.51 × 10−10 dB/m for Water (n = 1.33, Ethanol (n = 1.354 and Benzene (n = 1.366 respectively at 1.33 μm wavelength. The optimized P-PCF with higher sensitivity and lower confinement loss has high impact in the area of the chemical as well as gas sensing purposes.

  14. Interface-Confined High Crystalline Growth of Semiconducting Polymers at Graphene Fibers for High-Performance Wearable Supercapacitors. (United States)

    Padmajan Sasikala, Suchithra; Lee, Kyung Eun; Lim, Joonwon; Lee, Ho Jin; Koo, Sung Hwan; Kim, In Ho; Jung, Hong Ju; Kim, Sang Ouk


    We report graphene@polymer core-shell fibers (G@PFs) composed of N and Cu codoped porous graphene fiber cores uniformly coated with semiconducting polymer shell layers with superb electrochemical characteristics. Aqueous/organic interface-confined polymerization method produced robust highly crystalline uniform semiconducting polymer shells with high electrical conductivity and redox activity. When the resultant core-shell fibers are utilized for fiber supercapacitor application, high areal/volume capacitance and energy densities are attained along with long-term cycle stability. Desirable combination of mechanical flexibility, electrochemical properties, and facile process scalability makes our G@PFs particularly promising for portable and wearable electronics.

  15. Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

    CERN Document Server

    Nagayama, T; Florido, R; Mayes, D; Tommasini, R; Koch, J A; Delettrez, J A; Regan, S P; Smalyuk, V A


    Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional space-resolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.

  16. Animal MRI Core (United States)

    Federal Laboratory Consortium — The Animal Magnetic Resonance Imaging (MRI) Core develops and optimizes MRI methods for cardiovascular imaging of mice and rats. The Core provides imaging expertise,...

  17. Accuracy enhancement of laser induced breakdown spectra using permittivity and size optimized plasma confinement rings. (United States)

    Li, An; Guo, Shuai; Wazir, Nasrullah; Chai, Ke; Liang, Liang; Zhang, Min; Hao, Yan; Nan, Pengfei; Liu, Ruibin


    The inevitable problems in laser induced breakdown spectroscopy are matrix effect and statistical fluctuation of the spectral signal, which can be partly avoided by utilizing a proper confined unit. The dependences of spectral signal enhancement on relative permittivity were studied by varying materials to confine the plasma, which include polytetrafluoroethylene(PTFE), nylon/dacron, silicagel, and nitrile-butadiene rubber (NBR) with the relative permittivity 2.2, ~3.3, 3.6, 8~13, 15~22. We found that higher relative permittivity rings induce stronger enhancement ability, which restricts the energy dissipation of plasma better and due to the reflected electromagnetic wave from the wall of different materials, the electromagnetic field of plasma can be well confined and makes the distribution of plasma more orderly. The spectral intensities of the characteristic lines Si I 243.5 nm and Si I 263.1 nm increased approximately 2 times with relative permittivity values from 2.2 to ~20. The size dependent enhancement of PTFE was further checked and the maximum gain was realized by using a confinement ring with a diameter size of 5 mm and a height of 3 mm (D5mmH3mm), and the rings with D2mmH1mm and D3mmH2mm also show higher enhancement factor. In view of peak shift, peak lost and accidental peaks in the obtained spectra were properly treated in data progressing; the spectral fluctuation decreased drastically for various materials with different relative permittivities as confined units, which means the core of plasma is stabilized, attributing to the confinement effect. Furthermore, the quantitative analysis in coal shows wonderful results-the prediction fitting coefficient R2 reaches 0.98 for ash and 0.99 for both volatile and carbon.

  18. Photon upconversion in core-shell nanoparticles. (United States)

    Chen, Xian; Peng, Denfeng; Ju, Qiang; Wang, Feng


    Photon upconversion generally results from a series of successive electronic transitions within complex energy levels of lanthanide ions that are embedded in the lattice of a crystalline solid. In conventional lanthanide-doped upconversion nanoparticles, the dopant ions homogeneously distributed in the host lattice are readily accessible to surface quenchers and lose their excitation energy, giving rise to weak and susceptible emissions. Therefore, present studies on upconversion are mainly focused on core-shell nanoparticles comprising spatially confined dopant ions. By doping upconverting lanthanide ions in the interior of a core-shell nanoparticle, the upconversion emission can be substantially enhanced, and the optical integrity of the nanoparticles can be largely preserved. Optically active shells are also frequently employed to impart multiple functionalities to upconversion nanoparticles. Intriguingly, the core-shell design introduces the possibility of constructing novel upconversion nanoparticles by exploiting the energy exchange interactions across the core-shell interface. In this tutorial review, we highlight recent advances in the development of upconversion core-shell nanoparticles, with particular emphasis on the emerging strategies for regulating the interplay of dopant interactions through core-shell nanostructural engineering that leads to unprecedented upconversion properties. The improved control over photon energy conversion will open up new opportunities for biological and energy applications.

  19. Pulse propagation in a decoupled two-core fiber. (United States)

    Liu, M; Chiang, K S


    It is known that a decoupled two-core fiber can prevent monochromatic light at a specific wavelength (the decoupling wavelength) launched into one core from coupling to the other core. In this paper, we show that a pulse at the decoupling wavelength launched into one core of such a fiber inevitably splits into two pairs of pulses propagating in the two cores along the fiber. The minimum distance required for pulse splitting to be visible is inversely proportional to the coupling-coefficient dispersion in the fiber and linearly proportional to the pulse width. It would take only several centimeters of a recently demonstrated decoupled two-core photonic-bandgap fiber to observe the pulse-splitting effect with a 100-fs pulse. We also study the effects of self-phase modulation on the pulse propagation dynamics in a decoupled two-core fiber in both the normal and anomalous dispersion regimes.

  20. Regimes of miscible fluid thread formation in microfluidic focusing sections (United States)

    Cubaud, Thomas; Notaro, Sara


    We experimentally study the formation and stability of miscible fluid threads made of high-viscosity liquids using hydrodynamic focusing sections. Miscible core annular flows are useful for transporting viscous materials and can be destabilized for enhancing mass transfer. We delineate phase-diagrams of the generation of lubricated threads from low to large viscosity contrasts with various diffusion coefficients. Depending on fluid properties and flow rates of injection, stable microflows are classified into engulfment, thread, and tubing regimes. For low Péclet numbers, we examine thread dynamics when diffusive effects strongly alter basic flow structures and induce new flow configurations, including ultra-diffusive and diffusive instability regimes. Another unstable flow arrangement is investigated for moderate Reynolds numbers where small threads are rapidly destabilized in the inertial flow field of the sheath fluid near the fluid junction. This study provides an overview of stable and unstable flow regimes and their transitions during the formation of miscible viscous fluid filaments in square microchannels.

  1. Characterization of Strength of Intact Brittle Rock Considering Confinement-Dependent Failure Processes (United States)

    Kaiser, Peter K.; Kim, Bo-Hyun


    unconfined compression tests (UCS) alone, the confined strength may be underestimated by as much as 50 % (on average). If triaxial data with a limited confinement range (e.g., σ3 ≪ 0.5 UCS due to cell pressure limitations) are used, the confined strength may be overestimated. Therefore, the application of standard data fitting procedures, without consideration of confinement-dependent failure mechanisms, may lead to erroneous intact rock strength parameters when applied to brittle rocks, and consequently, by extrapolation, to correspondingly erroneous rock mass strength parameters. It follows that the strength characteristics of massive rock differ significantly in the direct vicinity of excavation from that which is remote with higher confinement. Therefore, it is recommended to adopt a differentiated approach to obtain intact rock strength parameters for engineering problems at lower confinement (near excavation; e.g., excavation stability assessment or support design), and at elevated confinement (typically, when the confinement exceeds about 10 % of the UCS) as might be encountered in wide pillar cores.

  2. Extra-dimensional confinement of quantum particles

    CERN Document Server

    Hedin, Eric R


    A basic theoretical framework is developed in which elementary particles have a component of their wave function extending into higher spatial dimensions. This model postulates an extension of the Schrodinger equation to include a 4th and 5th spatial component. A higher-dimensional simple harmonic oscillator confining potential localizes particles into 3-d space, characterizing the brane tension which confines Standard Model particles to the sub-manifold. Quantum effects allow a non-zero probability for a particle's evanescent existence in the higher dimensions, and suggest an experimental test for the validity of this model via particles being temporarily excited into the first excited state of the extra-dimensional potential well, in which their probability of existing in 3-d space transiently drops to zero. Several consistency checks of the outcomes of this extra-dimensional model are included in this paper. Among the outcomes of this model are: a match with the quantum phenomenon of zitterbewegung; the pr...

  3. Compaction of granular material inside confined geometries

    Directory of Open Access Journals (Sweden)

    Benjy eMarks


    Full Text Available In both nature and the laboratory, loosely packed granular materials are often compacted inside confined geometries. Here, we explore such behaviour in a quasi-two dimensional geometry, where parallel rigid walls provide the confinement. We use the discrete element method to investigate the stress distribution developed within the granular packing as a result of compaction due to the displacement of a rigid piston. We observe that the stress within the packing increases exponentially with the length of accumulated grains, and show an extension to current analytic models which fits the measured stress. The micromechanical behaviour is studied for a range of system parameters, and the limitations of existing analytic models are described. In particular, we show the smallest sized systems which can be treated using existing models. Additionally, the effects of increasing piston rate, and variations of the initial packing fraction, are described.

  4. Influence of confining layers' heterogeneity on the barometric response functions in semi-confined aquifers (United States)

    Redaelli, Marco; Perulero Serrano, Raul


    It has been shown that Barometric Response Functions (BRFs) can provide a useful tool for detecting the occurrence of highly conducive bodies which span across aquifer confining layers and can potentially give rise to pathways for pollutant migration (Hussein et al 2013, Odling et al 2015). Analytical models employed to estimate BRFs from geological system properties assume homogeneity within the aquifer and its confining layer. These assumptions are rarely satisfied in practice. Our study focusses on the impact on predicted BRFs of heterogeneous distribution of high conductivity geomaterials within the confining layer. The work is grounded on a suite of three-dimensional, transient numerical computations of groundwater flow in a confining layer-aquifer system for i) a perfectly homogeneous two-layer setting where a single highly conducive block is fully penetrating the confining layer and ii) a heterogeneous two-layer system where hydraulic conductivity in the confining layer is modelled as a stochastic process. Our numerical results are interpreted through a comparison against those associated with an analytical model which assumes system homogeneity. Monitoring points located in the middle of the modelled aquifer domain, mimicking screened boreholes in field conditions, are used to extract water level records. The output is used to obtain the corresponding BRFs (in terms of gain and phase components) and compared vis-a-vis the selected analytical solution. The results show a wide variety of BRF responses, especially in the gain component, which vary from almost confined to unconfined scenarios. Our simulations show that the BRFs are a viable tool to improve understanding of the degree of spatial continuity within low permeability heterogeneous geological materials such as glacial till which is frequently found overlying water bearing units across the UK and other localities worldwide. As such, it has the potential to improve groundwater vulnerability assessment

  5. Modeling Flow Coating of Colloidal Dispersions in the Evaporative Regime: Prediction of Deposit Thickness. (United States)

    Doumenc, Frédéric; Salmon, Jean-Baptiste; Guerrier, Béatrice


    We investigate flow coating processes, i.e., the formation of dry coatings starting from dilute complex fluids confined between a static blade and a moving substrate. In particular, we focus on the evaporative regime encountered at low substrate velocity, at which the coating flow is driven mainly by solvent evaporation in the liquid meniscus. In this regime, general arguments based on mass conservation show that the thickness of the dry film decreases as the substrate velocity increases, unlike the behavior in the well-known Landau-Levich regime. This work focuses on colloidal dispersions, which deserve special attention. Indeed, flow coating is expected to draw first a solvent-saturated film of densely packed colloids, which further dries fully when air invades the pores of the solid film. We first develop a model based on the transport equations for binary mixtures, which can describe this phenomenon continuously, using appropriate boundary conditions and a criterion to take into account pore-emptying in the colloidal film. Extensive numerical simulations of the model then demonstrate two regimes for the deposit thickness as a function of the process parameters (substrate velocity, evaporation rate, bulk concentration, and particle size). We finally derive an analytical model based on simplified transport equations that can reproduce the output of our numerical simulations very well. This model can predict analytically the two observed asymptotic regimes and therefore unifies the models recently reported in the literature.

  6. Confinement in anti-de Sitter space (United States)

    Aharony, Ofer; Berkooz, Micha; Tong, David; Yankielowicz, Shimon


    Four dimensional gauge theories in anti-de Sitter space, including pure Yang-Mills theory, exhibit a quantum phase transition between a deconfined phase and a confined phase as the gauge coupling is varied. We explore various mechanisms by which this may occur, both in a fixed background and in the presence of gravity. We also make a number of observations on the dynamics of four dimensional supersymmetric gauge theories in anti-de Sitter space.

  7. Rheology of Confined Non-Brownian Suspensions. (United States)

    Fornari, Walter; Brandt, Luca; Chaudhuri, Pinaki; Lopez, Cyan Umbert; Mitra, Dhrubaditya; Picano, Francesco


    We study the rheology of confined suspensions of neutrally buoyant rigid monodisperse spheres in plane-Couette flow using direct numerical simulations. We find that if the width of the channel is a (small) integer multiple of the sphere diameter, the spheres self-organize into two-dimensional layers that slide on each other and the effective viscosity of the suspension is significantly reduced. Each two-dimensional layer is found to be structurally liquidlike but its dynamics is frozen in time.

  8. Engineered barriers for radioactive waste confinement


    Fernández, R


    Nuclear power plants generate long-lived radioactive waste of high toxicity. The security assessment of repositories destined to definitive confinement of radioactive waste has been studied for several decades. Deep geological repositories are technically feasible and begin to be built by some pioneer countries. The scientific evaluation of interactions between the different engineered barriers is studied by laboratory experiments, natural analogues and modeling studies. The three methods are...

  9. The functionality-based application confinement model


    Schreuders, ZC; Payne, C.; Mcgill, T.


    This paper presents the functionality-based application confinement (FBAC) access control model. FBAC is an application-oriented access control model, intended to restrict processes to the behaviour that is authorised by end users, administrators, and processes, in order to limit the damage that can be caused by malicious code, due to software vulnerabilities or malware. FBAC is unique in its ability to limit applications to finely grained access control rules based on high-level easy-to-unde...

  10. Seismic retrofitting of reinforced concrete frame structures using GFRP-tube-confined-concrete composite braces (United States)

    Moghaddasi B., Nasim S.; Zhang, Yunfeng; Hu, Xiaobin


    This paper presents a new type of structural bracing intended for seismic retrofitting use in framed structures. This special composite brace, termed glass-fiber-reinforced-polymer (GFRP)-tube-confined-concrete composite brace, is comprised of concrete confined by a GFRP tube and an inner steel core for energy dissipation. Together with a contribution from the GFRP-tube confined concrete, the composite brace shows a substantially increased stiffness to control story drift, which is often a preferred feature in seismic retrofitting. An analysis model is established and implemented in a general finite element analysis program — OpenSees, for simulating the load-displacement behavior of the composite brace. Using this model, a parametric study of the hysteretic behavior (energy dissipation, stiffness, ductility and strength) of the composite brace was conducted under static cyclic loading and it was found that the area ratio of steel core to concrete has the greatest influence among all the parameters considered. To demonstrate the application of the composite brace in seismic retrofitting, a three-story nonductile reinforced concrete (RC) frame structure was retrofitted with the composite braces. Pushover analysis and nonlinear time-history analyses of the retrofitted RC frame structure was performed by employing a suite of 20 strong ground motion earthquake records. The analysis results show that the composite braces can effectively reduce the peak seismic responses of the RC frame structure without significantly increasing the base shear demand.

  11. Effects of Salinity and Confining Pressure on Hydration-Induced Fracture Propagation and Permeability of Mancos Shale (United States)

    Zhang, Shifeng; Sheng, James J.


    Low-salinity water imbibition was considered an enhanced recovery method in shale oil/gas reservoirs due to the resulting hydration-induced fractures, as observed at ambient conditions. To study the effect of confining pressure and salinity on hydration-induced fractures, time-elapsed computerized tomography (CT) was used to obtain cross-sectional images of shale cores. Based on the CT data of these cross-sectional images, cut faces parallel to the core axial in the middle of the core and 3D fracture images were also reconstructed. To study the effects of confining pressure and salinity on shale pore fluid flowing, shale permeability was measured with Nitrogen (N2), distilled water, 4% KCl solution, and 8% KCl solution. With confining pressures increased to 2 MPa or more, either in distilled water or in KCl solutions of different salinities, fractures were observed to close instead to propagate at the end of the tests. The intrinsic permeabilities of #1 and #2 Mancos shale cores were 60.0 and 7000 nD, respectively. When tested with distilled water, the permeability of #1 shale sample with 20.0 MPa confining pressure loaded, and #2 shale sample with 2.5 MPa confining pressure loaded, decreased to 0.45 and 15 nD, respectively. Using KCl can partly mitigate shale permeability degradation. Compared to 4% KCl, 8% KCl can decrease more permeability damage. From this point of view, high salinity KCl solution should be required for the water-based fracturing fluid.

  12. Spectral confinement and current for atoms in strong magnetic fields

    DEFF Research Database (Denmark)

    Fournais, Søren


    e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B<3......e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B

  13. Radiolysis of confined water: molecular hydrogen formation

    Energy Technology Data Exchange (ETDEWEB)

    Rotureau, P.; Renault, J.P.; Mialocq, J.C. [CEA/Saclay, DSM/DRECAM/SCM/URA 331 CNRS, 91191 Gif-sur-Yvette Cedex (France); Lebeau, B.; Patarin, J. [Laboratoire de Materiaux a Porosite Controlee, UMR CNRS 7016, ENSCMu-UHA, 3, Rue Alfred Werner, 68093 Mulhouse Cedex (France)


    The formation of molecular hydrogen in the radiolysis of water confined in nanoscale pores of well-characterised porous silica glasses and mesoporous molecular sieves (MCM-41) is examined. The comparison of dihydrogen formation by irradiation of both materials, dry and hydrated, shows that a large part of the H{sub 2} comes from the surface of the material. The radiolytic yields, G(H{sub 2})=(3{+-}0.5) x 10{sup -7} mol J{sup -1}, calculated using the total energy deposited in the material and the water, are only slightly affected by the degree of hydration of the material and by the pore size. These yields are also not modified by the presence of hydroxyl radical scavengers. This observation proves that the back reaction between H{sub 2} and HO{sup .} is inoperative in such confined environments. Furthermore, the large amount of H{sub 2} produced in the presence of different concentrated scavengers of the hydrated electron and its precursor suggests that these two species are far from being the only species responsible for the H{sub 2} formation. Our results show that the radiolytic phenomena that occur in water confined in nanoporous silica are dramatically different to those in bulk water, suggesting the need to investigate further the chemical reactivity in this type of environment. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  14. Radiolysis of confined water: molecular hydrogen formation. (United States)

    Rotureau, P; Renault, J P; Lebeau, B; Patarin, J; Mialocq, J-C


    The formation of molecular hydrogen in the radiolysis of water confined in nanoscale pores of well-characterised porous silica glasses and mesoporous molecular sieves (MCM-41) is examined. The comparison of dihydrogen formation by irradiation of both materials, dry and hydrated, shows that a large part of the H2 comes from the surface of the material. The radiolytic yields, G(H2)=(3+/-0.5)x10(-7) mol J(-1), calculated using the total energy deposited in the material and the water, are only slightly affected by the degree of hydration of the material and by the pore size. These yields are also not modified by the presence of hydroxyl radical scavengers. This observation proves that the back reaction between H2 and HO(.) is inoperative in such confined environments. Furthermore, the large amount of H2 produced in the presence of different concentrated scavengers of the hydrated electron and its precursor suggests that these two species are far from being the only species responsible for the H2 formation. Our results show that the radiolytic phenomena that occur in water confined in nanoporous silica are dramatically different to those in bulk water, suggesting the need to investigate further the chemical reactivity in this type of environment.

  15. Chemical reactions confined within carbon nanotubes. (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N


    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  16. Confined Tube Crimp Using Portable Hand Tools

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Joseph James [Los Alamos National Laboratory; Pereyra, R. A. [LANL Retired; Archuleta, Jeffrey Christopher [Los Alamos National Laboratory; Martinez, Isaac P. [Los Alamos National Laboratory; Nelson, A. M. [MST-16 Summer Student (2007); Allen, Ronald Scott [Los Alamos National Laboratory; Page, R. L. [LANL Retired; Freer, Jerry Eugene [Los Alamos National Laboratory; Dozhier, Nathan Gus [Los Alamos National Laboratory


    The Lawrence Radiation Laboratory developed handheld tools that crimp a 1/16 inch OD tube, forming a leak tight seal1 (see Figure 1). The leak tight seal forms by confining the 1/16 inch OD tubing inside a die while applying crimp pressure. Under confined pressure, the tube walls weld at the crimp. The purpose of this study was to determine conditions for fabricating a leak tight tube weld. The equipment was used on a trial-and-error basis, changing the conditions after each attempt until successful welds were fabricated. To better confine the tube, the die faces were polished. Polishing removed a few thousandths of an inch from the die face, resulting in a tighter grip on the tubing wall. Using detergent in an ultrasonic bath, the tubing was cleaned. Also, the time under crimp pressure was increased to 30 seconds. With these modifications, acceptable cold welds were fabricated. After setting the conditions for an acceptable cold weld, the tube was TIG welded across the crimped face.


    Directory of Open Access Journals (Sweden)

    J. M. Maluf


    Full Text Available In order to evaluate the performance and carcass characteristics of cattle cross breeds ½ Aberdeen Angus x ½Nelore and Nelore confined submitted to immunocastration 218 male animals were used, feedlot, averaging 342 kg, divided into three experimental groups, T1: 117 steers ½ Angus x ½ Nelore no castrated (ANC, T2: 51 Nelore steers uncastrated (NNC and T3: 50 Nellore steers immunocastrated (NIC. The experiment lasted 144 days of confinement. The selection of animals for group formation was according to the individual weight, breed, sex condition and age. For immunocastration it wasused Bopriva® vaccine. The rating was finished according to the parameter used by the meatpacking industry ranging from 1 to 5. The experimental design was completely randomized in three groups. For the analyzes the variables studied statistics were submitted to analysis of variance (ANOVA and Tukey test both at the 5% level of significance. The results showed differences (p <0.01 at various features of productive performance and carcass between treatments. For slaughter weight, the ANC animals were higher (with 582.1 kg to Nelore, regardless of sexual condition, and the NNC were in turn heavier than the NIC, 527.4 and 503.7 respectively. Finally, it observed that the use of immunocastration in Nellore animals provided a decrease in productive performance of confined animals, but provided better finish carcass similar to crossbred (ANC.

  18. Water nanodroplets confined in zeolite pores. (United States)

    Coudert, François-Xavier; Cailliez, Fabien; Vuilleumier, Rodolphe; Fuchs, Alain H; Boutin, Anne


    We provide a comprehensive depiction of the behaviour of a nanodroplet of approximately equal to 20 water molecules confined in the pores of a series of 3D-connected isostructural zeolites with varying acidity, by means of molecular simulations. Both grand canonical Monte Carlo simulations using classical interatomic forcefields and first-principles Car-Parrinello molecular dynamics were used in order to characterise the behaviour of confined water by computing a range of properties, from thermodynamic quantities to electronic properties such as dipole moment, including structural and dynamical information. From the thermodynamic point of view, we have identified the all-silica zeolite as hydrophobic, and the cationic zeolites as hydrophilic; the condensation transition in the first case was demonstrated to be of first order. Furthermore, in-depth analysis of the dynamical and electronic properties of water showed that water in the hydrophobic zeolite behaves as a nanodroplet trying to close its hydrogen-bond network onto itself, with a few short-lived dangling OH groups, while water in hydrophilic zeolites "opens up" to form weak hydrogen bonds with the zeolite oxygen atoms. Finally, the dipole moment of confined water is studied and the contributions of water self-polarisation and the zeolite electric field are discussed.

  19. Dynamics of Hyperbranched Polymers under Confinement (United States)

    Androulaki, Krystallenia; Chrissopoulou, Kiriaki; Anastasiadis, Spiros H.; Prevosto, Daniele; Labardi, Massimiliano


    The effect of severe confinement on the dynamics of three different generations of hyperbranched polyesters (Boltorns) is investigated by Dielectric Spectroscopy. The polymers are intercalated within the galleries of natural Na+-MMT, thus, forming 1nm polymer films confined between solid walls. The Tg's of the polymers determined by DSC show a clear dependence on the generation whereas the transition is completely suppressed when all the polymer chains are intercalated. The dynamic investigation of the bulk polymers reveals two sub-Tg processes, with similar behavior for the three polymers with the segmental relaxation observed above the Tg of each. For the nanocomposites, where all polymers are severely confined, the dynamics show significant differences compared to that of the bulk polymers. The sub-Tg processes are similar for the three generations but significantly faster and with weaker temperature dependence than those in the bulk. The segmental process appears at temperatures below the bulk polymer Tg, it exhibits an Arrhenius temperature dependence and shows differences for the three generations. A slow process that appears at higher temperatures is due to interfacial polarization. Co-financed by the EU and Greek funds through the Operational Program ``Education and Lifelong Learning'' of the NSRF-Research Funding Program: THALES-Investing in knowledge society through the Eur. Social Fund (MIS 377278) and COST Action MP0902-COINAPO.

  20. Quantum Confinement at Polar Oxide Interfaces (United States)

    Gariglio, Stefano; Li, Danfeng; Wu, Zhenping; Liu, Wei; Fete, Alexandre; Boselli, Margherita; Lemal, Sebastien; Bristowe, Nicholas; Ghosez, Philippe; Gabay, Marc; Triscone, Jean-Marc

    The discovery of a two-dimensional electron liquid (2DEL), confined at the interface between the two band insulators LaAlO3 (LAO) and SrTiO3 (STO) has generated tremendous research interest. The 2DEL confinement lifts the degeneracy of Ti t2 g orbitals and promotes exotic physical properties. A previous study has demonstrated that a 2DEL is also observed when LAO is alloyed with STO (La,Al)1-x(Sr,Ti)xO3 (LASTO: x). The threshold thickness required for the onset of conductivity scales with x. We present here a study of superconductivity at the (LASTO:0.5)/STO interface. The thickness of the 2DEL, measured using perpendicular and parallel critical fields, is larger than the one at the LAO/STO interface. This change is due to a modification on the confining potential linked to a reduced charge transfer that is scaling as 1 / x . This scenario is also confirmed by a self-consistent Poisson-Schrödinger model and ab initio calculations. These compelling evidences support an intrinsic origin to the formation of the 2DEL in the LAO/STO system.

  1. Confined Turbulent Swirling Recirculating Flow Predictions. Ph.D. Thesis (United States)

    Abujelala, M. T.


    Turbulent swirling flow, the STARPIC computer code, turbulence modeling of turbulent flows, the k-xi turbulence model and extensions, turbulence parameters deduction from swirling confined flow measurements, extension of the k-xi to confined swirling recirculating flows, and general predictions for confined turbulent swirling flow are discussed.

  2. Shock pressure induced by glass-confined laser shock peening: Experiments, modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xianqian; Song Hongwei; Wei Yanpeng; Wang Xi; Huang Chenguang [Key Laboratory for Hydrodynamics and Ocean Engineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Duan Zhuping [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)


    The shock pressure generated by the glass confined regime in laser shock peening and its attenuation in the target material are investigated. First, the particle velocity of the target back free surface induced by laser generated shock pressure of this regime is measured using a photonic Doppler velocimetry system. The temporal profile of the particle velocity at the back free surface, where the elastic precursor is captured, manifests a powerful diagnostic capability of this newly developed photonic Doppler velocimetry system for tracking the velocity on short time scales in shock-wave experiments. Second, a coupling pressure analytical model, in which the material constitutive models of confined layers and target material are considered, is proposed to predict the plasma pressure profile at the surface of target. Furthermore, using the predicted shock pressure profile as the input condition, the dynamic response of the target under the shock pressure is simulated by LS-DYNA. The simulated back free surface velocity profile agrees well with that measured by the photonic Doppler velocimetry system. Finally, the attenuation behavior of stress waves and particle velocities in the depth of the target is analyzed, and it indicates an exponential decay. The corresponding empirical formulas for the attenuation behavior are given based on the numerical results.

  3. Center-stabilized Yang-Mills Theory:Confinement and Large N Volume Independence

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, Mithat; /SLAC /Stanford U., Phys. Dept.; Yaffe, Laurence G.; /Washington U., Seattle


    We examine a double trace deformation of SU(N) Yang-Mills theory which, for large N and large volume, is equivalent to unmodified Yang-Mills theory up to O(1/N{sup 2}) corrections. In contrast to the unmodified theory, large N volume independence is valid in the deformed theory down to arbitrarily small volumes. The double trace deformation prevents the spontaneous breaking of center symmetry which would otherwise disrupt large N volume independence in small volumes. For small values of N, if the theory is formulated on R{sup 3} x S{sup 1} with a sufficiently small compactification size L, then an analytic treatment of the non-perturbative dynamics of the deformed theory is possible. In this regime, we show that the deformed Yang-Mills theory has a mass gap and exhibits linear confinement. Increasing the circumference L or number of colors N decreases the separation of scales on which the analytic treatment relies. However, there are no order parameters which distinguish the small and large radius regimes. Consequently, for small N the deformed theory provides a novel example of a locally four-dimensional pure gauge theory in which one has analytic control over confinement, while for large N it provides a simple fully reduced model for Yang-Mills theory. The construction is easily generalized to QCD and other QCD-like theories.

  4. Center-stabilized Yang-Mills theory: Confinement and large N volume independence (United States)

    Ünsal, Mithat; Yaffe, Laurence G.


    We examine a double trace deformation of SU(N) Yang-Mills theory which, for large N and large volume, is equivalent to unmodified Yang-Mills theory up to O(1/N2) corrections. In contrast to the unmodified theory, large N volume independence is valid in the deformed theory down to arbitrarily small volumes. The double trace deformation prevents the spontaneous breaking of center symmetry which would otherwise disrupt large N volume independence in small volumes. For small values of N, if the theory is formulated on R3×S1 with a sufficiently small compactification size L, then an analytic treatment of the nonperturbative dynamics of the deformed theory is possible. In this regime, we show that the deformed Yang-Mills theory has a mass gap and exhibits linear confinement. Increasing the circumference L or number of colors N decreases the separation of scales on which the analytic treatment relies. However, there are no order parameters which distinguish the small and large radius regimes. Consequently, for small N the deformed theory provides a novel example of a locally four-dimensional pure-gauge theory in which one has analytic control over confinement, while for large N it provides a simple fully reduced model for Yang-Mills theory. The construction is easily generalized to QCD and other QCD-like theories.

  5. Ultra-short pulse delivery at high average power with low-loss hollow core fibers coupled to TRUMPF's TruMicro laser platforms for industrial applications (United States)

    Baumbach, S.; Pricking, S.; Overbuschmann, J.; Nutsch, S.; Kleinbauer, J.; Gebs, R.; Tan, C.; Scelle, R.; Kahmann, M.; Budnicki, A.; Sutter, D. H.; Killi, A.


    Multi-megawatt ultrafast laser systems at micrometer wavelength are commonly used for material processing applications, including ablation, cutting and drilling of various materials or cleaving of display glass with excellent quality. There is a need for flexible and efficient beam guidance, avoiding free space propagation of light between the laser head and the processing unit. Solid core step index fibers are only feasible for delivering laser pulses with peak powers in the kW-regime due to the optical damage threshold in bulk silica. In contrast, hollow core fibers are capable of guiding ultra-short laser pulses with orders of magnitude higher peak powers. This is possible since a micro-structured cladding confines the light within the hollow core and therefore minimizes the spatial overlap between silica and the electro-magnetic field. We report on recent results of single-mode ultra-short pulse delivery over several meters in a lowloss hollow core fiber packaged with industrial connectors. TRUMPF's ultrafast TruMicro laser platforms equipped with advanced temperature control and precisely engineered opto-mechanical components provide excellent position and pointing stability. They are thus perfectly suited for passive coupling of ultra-short laser pulses into hollow core fibers. Neither active beam launching components nor beam trackers are necessary for a reliable beam delivery in a space and cost saving packaging. Long term tests with weeks of stable operation, excellent beam quality and an overall transmission efficiency of above 85 percent even at high average power confirm the reliability for industrial applications.

  6. Spatially resolved Raman spectroscopy on indium-catalyzed core-shell germanium nanowires: size effects

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Y; Zardo, I; Garma, T; Heiss, M; Fontcuberta i Morral, A [Walter Schottky Institut, Physik Department, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Cao, L Y; Brongersma, M L [Geballe Laboratory for Advanced Materials, 476 Lomita Mall, Stanford University, Stanford, CA 94305 (United States); Morante, J R; Arbiol, J [Departament d' Electronica, Universitat de Barcelona, 08028 Barcelona, CAT (Spain)


    The structure of indium-catalyzed germanium nanowires is investigated by atomic force microscopy, scanning confocal Raman spectroscopy and transmission electron microscopy. The nanowires are formed by a crystalline core and an amorphous shell. We find that the diameter of the crystalline core varies along the nanowire, down to few nanometers. Phonon confinement effects are observed in the regions where the crystalline region is the thinnest. The results are consistent with the thermally insulating behavior of the core-shell nanowires.

  7. Multiscale regime shifts and planetary boundaries

    NARCIS (Netherlands)

    Hughes, T.P.; Carpenter, S.; Rockstrom, J.; Scheffer, M.; Walker, B.


    Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a


    Directory of Open Access Journals (Sweden)

    S. V. Batsova


    Full Text Available Analysis of regimes of electro-consumption at RUP «BMZ» is carried out. It is shown that in conditions of rapid growth of prices for electric power one of the conditions of reduction of production expenses is to be the increase of efficiency of the electro-consumption regimes control.

  9. A new high performance field reversed configuration operating regime in the C-2 device

    Energy Technology Data Exchange (ETDEWEB)

    Tuszewski, M.; Smirnov, A.; Thompson, M. C.; Barnes, D.; Binderbauer, M. W.; Brown, R.; Bui, D. Q.; Clary, R.; Conroy, K. D.; Deng, B. H.; Dettrick, S. A.; Douglass, J. D.; Garate, E.; Glass, F. J.; Gota, H.; Guo, H.Y.; Gupta, D.; Gupta, S.; Kinley, J. S.; Knapp, K. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); and others


    Large field reversed configurations (FRCs) are produced in the C-2 device by combining dynamic formation and merging processes. The good confinement of these FRCs must be further improved to achieve sustainment with neutral beam (NB) injection and pellet fuelling. A plasma gun is installed at one end of the C-2 device to attempt electric field control of the FRC edge layer. The gun inward radial electric field counters the usual FRC spin-up and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. Better plasma centering is also obtained, presumably from line-tying to the gun electrodes. The combined effects of the plasma gun and of neutral beam injection lead to the high performance FRC operating regime, with FRC lifetimes up to 3 ms and with FRC confinement times improved by factors 2 to 4.

  10. DNA electrophoresis in confined, periodic geometries: a new lakes-straits model. (United States)

    Laachi, Nabil; Dorfman, Kevin D


    We present a method to study the dynamics of long DNA molecules inside a cubic array of confining spheres, connected through narrow openings. Our method is based on the coarse-grained, lakes-straits model of Zimm and is therefore much faster than Brownian dynamics simulations. In contrast to Zimm's approach, our method uses a standard stochastic kinetic simulation to account for the mass transfer through the narrow straits and the formation of new lakes. The different rates, or propensities, of the reactions are obtained using first-passage time statistics and a Monte Carlo sampling to compute the total free energy of the chain. The total free energy takes into account the self-avoiding nature of the chain as well as confinement effects from the impenetrable spheres. The mobilities of various chains agree with biased reptation theory at low and high fields. At moderate fields, confinement effects lead to a new regime of reptation where the mobility is a linear function of molecular weight and the dispersion is minimal.

  11. Stability and transport in magnetic confined plasmas; estabilidad y transporte en plasmas confinados magneticamente

    Energy Technology Data Exchange (ETDEWEB)

    Martinell, J.J.; Herrera, J.J.E.; Morozov, D.K.; Soboleva, T.K.; Vitela, E. [Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, A.P. 70-543, 04510 Mexico D.F. (Mexico)


    A tokamak is a device with a toroidal geometry that uses magnetic fields to confine a plasma inside a vacuum chamber, in order to produce thermonuclear fusion reactions, releasing large amounts of energy, larger than that employed in operating the device. There are two fundamental problems that have prevented us from achieving this goal: (1) the appearance of different instabilities that are capable of destroying confinement, and (2) the great energy losses resulting from transport to the plasma edge. For several years there has been an enormous effort to study the complex physics behind these two phenomena in order to understand the way they affect the plasma so it is possible to control the unwanted effects. In this Project, different aspects of the Tokamak plasma physics are studied, namely: (a) the transition phenomenon to an improved confinement mode (H mode), (b) the effect impurities have on plasma dynamics in the cooler edge region, (c) the processes leading to a detached divertor regime, which makes energy extraction more efficient, and (d) the burn control of a future nuclear fusion reactor using neural networks. All these are important problems and have to be well understood before the design and construction of a tokamak-based thermonuclear reactor can be undertaken. (Author)

  12. Food Regimes Revisited: A New Zealand Perspective

    Directory of Open Access Journals (Sweden)

    Michael Roche


    Full Text Available ‘Food Regimes’ was coined by Friedmann and McMichael in 1989 and provided a organising framework for a considerable amount of Australian and New Zealand research during a period of economic restructuring and ‘deregulation’. Subsequently Food regimes were overtaken by other perspectives in New Zealand and elsewhere including an interest in commodity productions chains, regulation, post-productivist landscapes, and post structural political economy. More recently McMichael has reintroduced Food Regimes to his analysis. The paper will compare and contrast McMichael’s earlier and more recent engagements with Food Regimes. The export meat, the dairy, and pip fruit industries of Zealand it will be used to illustrate points about the timing, boundaries and margins as well as the transformation of Food Regimes. Finally the paper will attempt to connect the more recent focus on commodity chain analysis and post productivist landscapes with McMichael’s renewed interest in food Regimes.

  13. Effects of microchannel confinement on acoustic vaporisation of ultrasound phase change contrast agents (United States)

    Lin, Shengtao; Zhang, Ge; Hau Leow, Chee; Tang, Meng-Xing


    The sub-micron phase change contrast agent (PCCA) composed of a perfluorocarbon liquid core can be activated into gaseous state and form stable echogenic microbubbles for contrast-enhanced ultrasound imaging. It has shown great promise in imaging microvasculature, tumour microenvironment, and cancer cells. Although PCCAs have been extensively studied for different diagnostic and therapeutic applications, the effect of biologically geometrical confinement on the acoustic vaporisation of PCCAs is still not clear. We have investigated the difference in PCCA-produced ultrasound contrast enhancement after acoustic activation with and without a microvessel confinement on a microchannel phantom. The experimental results indicated more than one-order of magnitude less acoustic vaporisation in a microchannel than that in a free environment taking into account the attenuation effect of the vessel on the microbubble scattering. This may provide an improved understanding in the applications of PCCAs in vivo.

  14. Ring Opening Metathesis Polymerization of Cyclopentene Using a Ruthenium Catalyst Confined by a Branched Polymer Architecture

    KAUST Repository

    Mugemana, Clement


    Multi-arm polystyrene stars functionalized with Grubbs-type catalysts in their cores were synthesized and used for the ring-opening metathesis polymerization (ROMP) of cyclopentene. The spatial confinement of the catalytic sites and the nanoscale phase separation between polystyrene and the growing polypentenamer chains lead to a dramatic inhibition of the ROMP termination and chain transfer steps. Consequently, cyclopentene polymerizations proceeded fast and with a high degree of conversion even in air. The Grubbs second generation catalyst was oxidatively inactivated under the same conditions. In contrast to conventional small-molecule catalysts, the ultimate degree of conversion of cyclopentene monomer and the polydispersity of the product polypentenamer are not affected by the temperature. This indicates that spatial confinement of the catalyst resulted in a significant change in the activation parameters for the alkene metathesis ring-opening.

  15. Effects of microchannel confinement on acoustic vaporisation of ultrasound phase change contrast agents. (United States)

    Lin, Shengtao; Zhang, Ge; Leow, Chee Hau; Tang, Meng-Xing


    The sub-micron phase change contrast agent (PCCA) composed of a perfluorocarbon liquid core can be activated into gaseous state and form stable echogenic microbubbles for contrast-enhanced ultrasound imaging. It has shown great promise in imaging microvasculature, tumour microenvironment, and cancer cells. Although PCCAs have been extensively studied for different diagnostic and therapeutic applications, the effect of biologically geometrical confinement on the acoustic vaporisation of PCCAs is still not clear. We have investigated the difference in PCCA-produced ultrasound contrast enhancement after acoustic activation with and without a microvessel confinement on a microchannel phantom. The experimental results indicated more than one-order of magnitude less acoustic vaporisation in a microchannel than that in a free environment taking into account the attenuation effect of the vessel on the microbubble scattering. This may provide an improved understanding in the applications of PCCAs in vivo.

  16. Generalized inflation and confinement phase transitions in the early universe. (United States)

    Patzelt, H.


    Giving up the restriction ɛ/p = const, the author shows that equations of state with ɛ-3p = Δ > 0 will be driven to the inflationary solution with ɛ = -p after sufficiently long times. Subsequently, he shows that confinement transitions may provide such an equation of state due to a change of degrees of freedom. Depending on the energy scale of the confinement transition inflation may occur during confinement. Numerical results for quark and subquark confinement are given. For QCD-confinement the transition time is too short, compared to the energy density, for a significant deviation of the scale factor to occur.

  17. Generalized inflation and confinement phase transitions in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Patzelt, H. (Muenchen Univ. (Germany, F.R.). Sektion Physik)


    Giving up the restriction {epsilon}/p=const, we show that equations of state with {epsilon}-3p={Delta}>0 will be driven to the inflationary solution with {epsilon}=-p after sufficiently long times. Subsequently, we show that confinement transitions may provide such an equation of state due to a change of degrees of freedom. Depending on the energy scale of the confinement transition inflation may occur during confinement. Numerical results for quark and subquark confinement are given. For QCD-confinement the transition time is too short, compared to the energy density, for a significant deviation of the scale factor to occur. (orig.).

  18. What do fault patterns reveal about the latest phase of extension within the Northern Snake Range metamorphic core complex, Nevada, USA? (United States)

    Ismat, Zeshan; Riley, Paul; Lerback, Jory


    The Northern Snake Range is a classic example of a metamorphic core complex, Basin-and-Range province, United States. It is composed of a plastically deformed footwall and a brittlely deformed hanging wall, separated by the Northern Snake Range low-angle detachment (NSRD). Brittle deformation, however, is not confined to the hanging wall. This paper focuses on exposures in Cove Canyon, located on the SE flank of the Northern Snake Range, where penetrative, homogeneous faults are well exposed throughout the hanging wall, footwall and NSRD, and overprint early plastic deformation. These late-stage fault sets assisted Eocene-Miocene extension. Detailed analysis of the faults reveals the following: (1) The shortening direction defined by faults is similar to the shortening direction defined by the stretching lineation in the footwall mylonites, indicating that the extensional kinematic history remained unchanged as the rocks were uplifted into the elastico-frictional regime. (2) After ∼17 Ma, extension may have continued entirely within elastic-frictional regime via cataclastic flow. (3) This latest deformation phase may have been accommodated by a single, continuous event. (3) Faults within NSRD boudins indicate that deformation within the detachment zone was non-coaxial during the latest phase of extension.

  19. k -core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, P.; Estevez Fernandez, M.A.; Fiestras-Janeiro, M.G.; Mosquera, M.A.


    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  20. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  1. Improved energy confinement with nonlinear isotope effects in magnetically confined plasmas

    CERN Document Server

    Garcia, J; Jenko, F


    The efficient production of electricity from nuclear fusion in magnetically confined plasmas relies on a good confinement of the thermal energy. For more than thirty years, the observation that such confinement depends on the mass of the plasma isotope and its interaction with apparently unrelated plasma conditions has remained largely unexplained and it has become one of the main unsolved issues. By means of numerical studies based on the gyrokinetic theory, we quantitatively show how the plasma microturbulence depends on the isotope mass through nonlinear multiscale microturbulence effects involving the interplay between zonal flows, electromagnetic effects and the torque applied. This finding has crucial consequences for the design of future reactors since, in spite of the fact that they will be composed by multiple ion species, their extrapolation from present day experiments heavily relies on the knowledge obtained from a long experimental tradition based in single isotope plasmas.

  2. Nonlinear optical properties of free standing films of PbS quantum dots in the nonresonant femtosecond regime (United States)

    Kurian, Pushpa Ann; Vijayan, C.; Nag, Amit; Goswami, Debabrata


    Devices based on optical technology for high speed communication networks require materials with large nonlinear optical response in the ultrafast regime. Nonlinear optical materials have also attracted wide attention as potential candidates for the protection of optical sensors and eyes while handling lasers. Optical limiters have a constant transmittance at low input influence and a decrease in transmittance at higher fluences and are based on a variety of mechanisms such as nonlinear refraction, nonlinear scattering, multiphoton absorption and free carrier absorption. As we go from bulk to nanosized materials especially in the strong quantum confinement regime where radius of the nanoparticle is less than the bulk exciton Bohr radius, the optical nonlinearity is enhanced due to quantum confinement effect. This paper is on the ultrafast nonresonant nonlinearity in free standing films of PbS quantum dots stabilized in a synthetic glue matrix by a simple chemical route which provides flexibility of processing in a variety of physical forms. Optical absorption spectrum shows significant blue shift from the bulk absorption onset indicating strong quantum confinement. PbS quantumdots of mean size 3.3nm are characterized by X-ray diffraction and transmission electron microscopy. The mechanism of nonlinear absorption giving rise to optical limiting is probed using open z-scan technique with laser pulses of 150 fs pulse duration at 780 nm and the results are presented in the nonresonant femtosecond regime. Irradiance dependence on nonlinear absorption are discussed.

  3. Heat transfer regimes for a flow of water at supercritcal conditions in vertical channels (United States)

    Deev, V. I.; Kharitonov, V. S.; Churkin, A. N.; Baisov, A. M.


    Heat transfer regimes observed in experiments with water at supercritical conditions flowing in vertical channels of various cross-sections (such as round pipes, annulus, or rod bundles) are analyzed. In accordance with the established practice, the normal and the deteriorated heat transfer regimes were singled out as the basic regimes specific for heat carriers with highly variable properties. At the same time, it has been established that most published experimental data on supercritical pressure water heat transfer along the length of test sections demonstrate combined (or transient) heat transfer regimes. The features can be presented as a superposition of characteristics of the above-mentioned basic regimes. The combined regimes are not stable in certain ranges of water flow conditions in which sudden transitions between the basic regimes can occur. A system of similarity criteria governing heat transfer rate in the vicinity of the critical point is examined. As applicable to cores of water-cooled reactors, due to a small hydraulic diameter of cooling channels, buoyancy forces acting in these channels are negligible as compared with the inertia effects caused by thermal acceleration of the flow and viscous force. This concept yields two integrated criteria whose use in the correction factors for the basic heat transfer equation, which we proposed previously for the normal regimes, adequately (with an error of 20-25%) describes the specific of the heat transfer coefficient in the normal, deteriorated, and combined regimes. A system of equations is proposed for design calculation of heat transfer in channels of nuclear reactors cooled with supercritical pressure water.

  4. Regulatory regimes and bank behavior

    Directory of Open Access Journals (Sweden)

    Seok Weon Lee


    Full Text Available The purpose of this paper is to examine how the risk-taking behavior differed between Korean regional banks and national banks for the two different regulatory regimes; a very loose regulation period (1994-1997 and a very tightened regulation period (1998-2005. From the panel analysis over the period 1994-2005, we found that regional banks took riskier strategies than national banks when banking regulations are loose. Moreover, their higher risk-taking contributed to higher profit under the period of loose regulation. However, after the banking regulations were tightened after financial crisis around the late 1990s, this phenomenon disappeared and the tendency of regional banks to take greater risk than national banks was not observed any more. Also, the positive relationship between risk-taking and profitability was not observed either after regulations were tightened. These empirical findings would have the following policy implications. When the economic conditions are good, and therefore, banking regulations are relatively loose, the greater risk-taking of regional banks could be profitable, because regional banks are in a better situation in terms of maintaining their market share based on the close ties with their regional clients, and can be protected from excessive competition with national banks. But, if the economic conditions get worse and financial crisis occurs, and therefore, banking regulations get tightened, regional banks are more adversely and sensitively affected by these shocks than national banks because their size is small and their assets are less diversified than national banks, especially being concentrated on loans to small and medium size business sector and real estate loans, which are very sensitive to the fluctuation of the economy. Furthermore, if these adverse economic and financial shocks continue long, the probability of regional banks to fail would be substantially higher and it can cause a serious damage to

  5. Extension of high-beta plasma operation to low-collisionality regime (United States)

    Sakakibara, S.; Watanabe, K. Y.; Funaba, H.; Suzuki, Y.; Ohdachi, S.; Ida, K.; Tanaka, K.; Tokuzawa, T.; Morisaki, T.; Osakabe, M.; Takeiri, Y.; LHD Experiment Group


    In the large helical device, plasma with more than 4% average beta was successfully produced by multi-pellet injections in a regime with a collisionality one order of magnitude lower than that in previous high-beta operations. An improvement in particle confinement was observed during a high-beta discharge produced by a gas puff, and particle flux to the divertor was reduced by more than 40%. High instabilities at the plasma edge occurred and suppressed the increment of the average beta to 3.4%. A spontaneous change in the magnetic topology contributes to an increase in the average beta value while triggering the excitation of edge MHD instabilities.

  6. Spherical microwave confinement and ball lightning (United States)

    Robinson, William Richard

    This dissertation presents the results of research done on unconventional energy technologies from 1995 to 2009. The present civilization depends on an infrastructure that was constructed and is maintained almost entirely using concentrated fuels and ores, both of which will run out. Diffuse renewable energy sources rely on this same infrastructure, and hence face the same limitations. I first examined sonoluminescence directed toward fusion, but demonstrated theoretically that this is impossible. I next studied Low Energy Nuclear Reactions and developed methods for improving results, although these have not been implemented. In 2000, I began Spherical Microwave Confinement (SMC), which confines and heats plasma with microwaves in a spherical chamber. The reactor was designed and built to provide the data needed to investigate the possibility of achieving fusion conditions with microwave confinement. A second objective was to attempt to create ball lightning (BL). The reactor featured 20 magnetrons, which were driven by a capacitor bank and operated in a 0.2 s pulse mode at 2.45 GHz. These provided 20 kW to an icosahedral array of 20 antennas. Video of plasmas led to a redesign of the antennas to provide better coupling of the microwaves to the plasma. A second improvement was a grid at the base of the antennas, which provided corona electrons and an electric field to aid quick formation of plasmas. Although fusion conditions were never achieved and ball lightning not observed, experience gained from operating this basic, affordable system has been incorporated in a more sophisticated reactor design intended for future research. This would use magnets that were originally planned. The cusp geometry of the magnetic fields is suitable for electron cyclotron resonance in the same type of closed surface that in existing reactors has generated high-temperature plasmas. Should ball lightning be created, it could be a practical power source with nearly ideal

  7. Confined Acoustic Phonons in Colloidal Nanorod Heterostructures Investigated by Nonresonant Raman Spectroscopy and Finite Elements Simulations. (United States)

    Miscuglio, Mario; Lin, Miao-Ling; Di Stasio, Francesco; Tan, Ping-Heng; Krahne, Roman


    Lattice vibrational modes in cadmium chalcogenide nanocrystals (NCs) have a strong impact on the carrier dynamics of excitons in such confined systems and on the optical properties of these nanomaterials. A prominent material for light emitting applications are CdSe/CdS core-shell dot-in-rods. Here we present a detailed investigation of the acoustic phonon modes in such dot-in-rods by nonresonant Raman spectroscopy with laser excitation energy lower than their bandgap. With high signal-to-noise ratio in the frequency range from 5-50 cm -1 , we reveal distinct Raman bands that can be related to confined extensional and radial-breathing modes (RBM). Comparison of the experimental results with finite elements simulation and analytical analysis gives detailed insight into the localized nature of the acoustic vibration modes and their resonant frequencies. In particular, the RBM of dot-in-rods cannot be understood by an oscillation of a CdSe sphere embedded in a CdS rod matrix. Instead, the dot-in-rod architecture leads to a reduction of the sound velocity in the core region of the rod, which results in a redshift of the rod RBM frequency and localization of the phonon induced strain in vicinity of the core where optical transitions occur. Such localized effects potentially can be exploited as a tool to tune exciton-phonon coupling in nanocrystal heterostructures.

  8. Fluctuation reduction and enhanced confinement in the MST reversed-field pinch

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, Brett Edward [Univ. of Wisconsin, Madison, WI (United States)


    Plasmas with a factor of ≥3 improvement in energy confinement have been achieved in the MST reversed-field pinch (RFP). These plasmas occur spontaneously, following sawtooth crashes, subject to constraints on, eg, toroidal magnetic field reversal and wall conditioning. Possible contributors to the improved confinement include a reduction of core-resonant, global magnetic fluctuations and a reduction of electrostatic fluctuations over the entire plasma edge. One feature of these plasmas is a region of strong ExB flow shear in the edge. Never before observed in conjunction with enhanced confinement in the RFP, such shear is common in enhanced confinement discharges in tokamaks and stellarators. Another feature of these plasmas is a new type of discrete dynamo event. Like sawtooth crashes, a common form of discrete dynamo, these events correspond to bursts of edge parallel current. The reduction of electrostatic fluctuations in these plasmas occurs within and beyond the region of strong ExB flow shear, similar to what is observed in tokamaks and stellarators. However, the reductions in the MST include fluctuations whose correlation lengths are larger than the width of the shear region. The reduction of the global magnetic fluctuations is most likely due to flattening of the μ=μ0$\\vec{J}$∙$\\vec{B}$/B2 profile. Flattening can occur, eg, due to the new type of discrete dynamo event and reduced edge resistivity. Enhanced confinement plasmas are also achieved in the MST when auxiliary current is applied to flatten the μ profile and reduce magnetic fluctuations. Unexpectedly, these plasmas also exhibit a region (broader than in the case above) of strong ExB flow shear in the edge, an edge-wide reduction of electrostatic fluctuations, and the new type of discrete dynamo event. Auxiliary current drive has historically been viewed as the principal route to fusion reactor viability for the RFP.

  9. Dynamics of Liquids Confined in Porous Materials

    DEFF Research Database (Denmark)

    Berg, Marcella Cabrera

    to the understanding of the nature of the hydration in the GIC and can be applied towards the development and improvement of dental restorative materials. Furthermore, two manuscripts regarding water and protein dynamics in confinement probed by quasi-elastic neutron scattering are also included in the thesis, Paper 3...... and Paper 4. In Paper 3 we investigated why two chalk samples display vastly different water uptake, despite the fact that they are known to have similar pore volumes. In Paper 4 we investigated the dynamics of encapsulated Hepatitis B surface antigen in mesoporous silica SBA-15. My knowledge of liquids...

  10. Confining quark condensate model of the nucleon.

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Michael; Tandy, Peter


    We obtain a mean-field solution for the nucleon as a quark-meson soliton obtained from the action of the global color-symmetry model of QCD. All dynamics is generated from an effective interaction of quark currents. At the quark-meson level there are two novel features: (1) absolute confinement is produced from the space-time structure of the dynamical self-energy in the vacuum quark propagator; and (2) the related scalar meson field is an extended q-barq composite that couples nonlocally to quarks. The influence of these features upon the nucleon mass contributions and other nucleon properties is presented.

  11. The Gribov theory of quark confinement

    CERN Document Server


    V N Gribov, one of the founders of modern particle physics, shaped our understanding of QCD as the microscopic dynamics of hadrons. This volume collects his papers on quark confinement, showing the road he followed to arrive at the theory and formulating the theory itself. It begins with papers providing a beautiful physical explanation of asymptotic freedom based on the phenomenon of antiscreening and demonstrating the inconsistency of the standard perturbative treatment of the gluon fields (Gribov copies, Gribov horizon). It continues with papers presenting the Gribov theory according to whi

  12. Isolation and confinement - Considerations for colonization (United States)

    Akins, F. R.


    This paper discusses three types of isolation (sensory/perceptual, temporal, and social) that could adversely affect mankind in space. The literature dealing with laboratory and field experiments relevant to these areas is summarized and suggestions are given for dealing with these problems within the space colony community. Also, consideration is given to the potential effects of physical confinement and the need for usable space. Finally, a modification of Maslow's hierarchy of needs is proposed as a theoretical framework to understand and investigate mankind's psychological needs in space.

  13. Honeycomb optical lattices with harmonic confinement

    DEFF Research Database (Denmark)

    Jacobsen, Jens Kusk Block; Nygaard, Nicolai


    We consider the fate of the Dirac points in the spectrum of a honeycomb optical lattice in the presence of a harmonic confining potential. By numerically solving the tight binding model, we calculate the density of states and find that the energy dependence can be understood from analytical...... arguments. In addition, we show that the density of states of the harmonically trapped lattice system can be understood by application of a local density approximation based on the density of states in the homogeneous lattice. The Dirac points are found to survive locally in the trap as evidenced...

  14. Diamond Ablators for Inertial Confinement Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H


    Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

  15. Magnetic confinement of repelling Bloch walls (United States)

    Magyari, E.; Thomas, H.


    In a ferromagnet with orthorhombic magneto-crystalline anisotropy, two repelling 180° domain walls (π kinks) can be pushed together to form a 360° domain wall (2π kink) by applying a magnetic field in the easy direction. We show that such a magnetically confined static 360° plane domain wall with Bloch-like structure, connecting two semi-infinite domains with parallel spin orientation, is linearly stable only below a critical strength Bc of the applied field. At B = Bc it becomes unstable with respect to a mode with spin component along the hard direction.

  16. Estimation of optimal dynamic treatment regimes. (United States)

    Zhao, Ying-Qi; Laber, Eric B


    Recent advances in medical research suggest that the optimal treatment rules should be adaptive to patients over time. This has led to an increasing interest in studying dynamic treatment regime, a sequence of individualized treatment rules, one per stage of clinical intervention, which maps present patient information to a recommended treatment. There has been a recent surge of statistical work for estimating optimal dynamic treatment regimes from randomized and observational studies. The purpose of this article is to review recent methodological progress and applied issues associated with estimating optimal dynamic treatment regimes. We discuss sequential multiple assignment randomized trials, a clinical trial design used to study treatment sequences. We use a common estimator of an optimal dynamic treatment regime that applies to sequential multiple assignment randomized trials data as a platform to discuss several practical and methodological issues. We provide a limited survey of practical issues associated with modeling sequential multiple assignment randomized trials data. We review some existing estimators of optimal dynamic treatment regimes and discuss practical issues associated with these methods including model building, missing data, statistical inference, and choosing an outcome when only non-responders are re-randomized. We mainly focus on the estimation and inference of dynamic treatment regimes using sequential multiple assignment randomized trials data. Dynamic treatment regimes can also be constructed from observational data, which may be easier to obtain in practice; however, care must be taken to account for potential confounding. © The Author(s), 2014.

  17. Mixing with applications to inertial-confinement-fusion implosions. (United States)

    Rana, V; Lim, H; Melvin, J; Glimm, J; Cheng, B; Sharp, D H


    Approximate one-dimensional (1D) as well as 2D and 3D simulations are playing an important supporting role in the design and analysis of future experiments at National Ignition Facility. This paper is mainly concerned with 1D simulations, used extensively in design and optimization. We couple a 1D buoyancy-drag mix model for the mixing zone edges with a 1D inertial confinement fusion simulation code. This analysis predicts that National Ignition Campaign (NIC) designs are located close to a performance cliff, so modeling errors, design features (fill tube and tent) and additional, unmodeled instabilities could lead to significant levels of mix. The performance cliff we identify is associated with multimode plastic ablator (CH) mix into the hot-spot deuterium and tritium (DT). The buoyancy-drag mix model is mode number independent and selects implicitly a range of maximum growth modes. Our main conclusion is that single effect instabilities are predicted not to lead to hot-spot mix, while combined mode mixing effects are predicted to affect hot-spot thermodynamics and possibly hot-spot mix. Combined with the stagnation Rayleigh-Taylor instability, we find the potential for mix effects in combination with the ice-to-gas DT boundary, numerical effects of Eulerian species CH concentration diffusion, and ablation-driven instabilities. With the help of a convenient package of plasma transport parameters developed here, we give an approximate determination of these quantities in the regime relevant to the NIC experiments, while ruling out a variety of mix possibilities. Plasma transport parameters affect the 1D buoyancy-drag mix model primarily through its phenomenological drag coefficient as well as the 1D hydro model to which the buoyancy-drag equation is coupled.

  18. Mixing with applications to inertial-confinement-fusion implosions (United States)

    Rana, V.; Lim, H.; Melvin, J.; Glimm, J.; Cheng, B.; Sharp, D. H.


    Approximate one-dimensional (1D) as well as 2D and 3D simulations are playing an important supporting role in the design and analysis of future experiments at National Ignition Facility. This paper is mainly concerned with 1D simulations, used extensively in design and optimization. We couple a 1D buoyancy-drag mix model for the mixing zone edges with a 1D inertial confinement fusion simulation code. This analysis predicts that National Ignition Campaign (NIC) designs are located close to a performance cliff, so modeling errors, design features (fill tube and tent) and additional, unmodeled instabilities could lead to significant levels of mix. The performance cliff we identify is associated with multimode plastic ablator (CH) mix into the hot-spot deuterium and tritium (DT). The buoyancy-drag mix model is mode number independent and selects implicitly a range of maximum growth modes. Our main conclusion is that single effect instabilities are predicted not to lead to hot-spot mix, while combined mode mixing effects are predicted to affect hot-spot thermodynamics and possibly hot-spot mix. Combined with the stagnation Rayleigh-Taylor instability, we find the potential for mix effects in combination with the ice-to-gas DT boundary, numerical effects of Eulerian species CH concentration diffusion, and ablation-driven instabilities. With the help of a convenient package of plasma transport parameters developed here, we give an approximate determination of these quantities in the regime relevant to the NIC experiments, while ruling out a variety of mix possibilities. Plasma transport parameters affect the 1D buoyancy-drag mix model primarily through its phenomenological drag coefficient as well as the 1D hydro model to which the buoyancy-drag equation is coupled.

  19. Confinement of Reinforced-Concrete Columns with Non-Code Compliant Confining Reinforcement plus Supplemental Pen-Binder

    Directory of Open Access Journals (Sweden)

    Anang Kristianto


    Full Text Available One of the important requirements for earthquake resistant building related to confinement is the use of seismic hooks in the hoop or confining reinforcement of reinforced-concrete column elements. However, installation of a confining reinforcement with a 135-degree hook is not easy. Therefore, in practice, many construction workers apply a confining reinforcement with a 90-degreehook (non-code compliant. Based on research and records of recent earthquakes in Indonesia, the use of a non-code compliant confining reinforcement for concrete columns produces structures with poor seismic performance. This paper presents a study that introduces an additional element that is expected to improve the effectiveness of concrete columns confined with a non-code compliant confining reinforcement. The additional element, named a pen-binder, is used to keep the non-code compliant confining reinforcement in place. The effectiveness of this element under pure axial concentric loading was investigatedcomprehensively.The specimens tested in this study were 18 concrete columns,with a cross-section of 170 mm x 170 mm and a height of 480 mm. The main test variables were the material type of the pen-binder, the angle of the hook, and the confining reinforcement configuration.The test results indicate that adding pen-binders can effectively improve the strength and ductility of the column specimens confined with a non-code compliant confining reinforcement

  20. Can Old Regimes Handle New Wars?

    DEFF Research Database (Denmark)

    Henningsen, Troels

    Research on New Wars argues that since the 1980s states and regimes have become more vulnerable to violence from non-state actors. Two developments in the Sahel region support the New Wars thesis: an increase in Islamist radicalization and new access to the global black market, both of which......, the paper finds that regimes in the Sahel region are still able to cope with the rise in non-state threats. The paper first shortly compares the longevity of the present regimes in the Sahel region to all previous ones, second examines in-depth how Chad and Mali fight the insurgents. Findings are that since...

  1. Magnetic Bion Condensation: A New Mechanism ofConfinement and Mass Gap in Four Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, Mithat; /SLAC /Stanford U., Phys. Dept.


    In recent work, we derived the long distance confining dynamics of certain QCD-like gauge theories formulated on small S{sup 1} x R{sup 3} based on symmetries, an index theorem and abelian duality. Here, we give the microscopic derivation. The solution reveals a new mechanism of confinement in QCD(adj) in the regime where we have control over both perturbative and nonperturbative aspects. In particular, consider SU(2) QCD(adj) theory with 1 {le} n{sub f} {le} 4 Majorana fermions, a theory which undergoes gauge symmetry breaking at small S{sup 1}. If the magnetic charge of the BPS monopole is normalized to unity, we show that confinement occurs due to condensation of objects with magnetic charge 2, not 1. Due to index theorems, we know that such an object cannot be a two identical monopole configuration. Its net topological charge must vanish, and hence it must be topologically indistinguishable from the perturbative vacuum. We construct such objects, the magnetically charged, topologically null molecules of a BPS monopole and {bar K}{bar K} antimonopole, which we refer as magnetic bions. An immediate puzzle with this proposal is the apparent Coulomb repulsion between BPS-{bar K}{bar K} pair. An attraction which overcomes the Coulomb repulsion between the two is induced by 2n{sub f} -fermion exchange. Bion condensation is also the mechanism of confinement in N = 1 SYM on the same four-manifold. The SU(N) generalization hints a possible hidden integrability behind nonsupersymmetric QCD of affine Toda type, and allows us to analytically compute the string tensions and thicknesses. We currently do not know the extension to R{sup 4}.

  2. Dynamical vanishing of the order parameter in a confined Bardeen-Cooper-Schrieffer Fermi gas after an interaction quench (United States)

    Hannibal, S.; Kettmann, P.; Croitoru, M. D.; Axt, V. M.; Kuhn, T.


    We present a numerical study of the Higgs mode in an ultracold confined Fermi gas after an interaction quench and find a dynamical vanishing of the superfluid order parameter. Our calculations are done within a microscopic density-matrix approach in the Bogoliubov-de Gennes framework which takes the three-dimensional cigar-shaped confinement explicitly into account. In this framework, we study the amplitude mode of the order parameter after interaction quenches starting on the BCS side of the BEC-BCS crossover close to the transition and ending in the BCS regime. We demonstrate the emergence of a dynamically vanishing superfluid order parameter in the spatiotemporal dynamics in a three-dimensional trap. Further, we show that the signal averaged over the whole trap mirrors the spatiotemporal behavior and allows us to systematically study the effects of the system size and aspect ratio on the observed dynamics. Our analysis enables us to connect the confinement-induced modifications of the dynamics to the pairing properties of the system. Finally, we demonstrate that the signature of the Higgs mode is contained in the dynamical signal of the condensate fraction, which, therefore, might provide a new experimental access to the nonadiabatic regime of the Higgs mode.

  3. Confinement and the supercritical Pomeron in QCD (United States)

    White, Alan R.


    Deep-inelastic diffractive scaling violations have provided fundamental insight into the QCD Pomeron, suggesting a single-gluon inner structure rather than that of a perturbative two-gluon bound state. This paper derives a high-energy, transverse momentum cutoff, confining solution of QCD. The Pomeron, in a first approximation, is a single Reggeized gluon plus a ``wee-parton'' component that compensates for the color and particle properties of the gluon. This solution corresponds to a supercritical phase of Reggeon field theory. Beginning with the multi-Regge behavior of massive quark and gluon amplitudes, Reggeon unitarity is used to derive a Reggeon diagram description of a wide class of multi-Regge amplitudes, including those describing the formation and scattering of bound-state Regge poles. When quark and gluon masses are taken to zero, a logarithmic divergence is produced by helicity-flip Reggeon interactions containing the infrared quark triangle anomaly. With the gauge symmetry partially broken, this divergence selects the bound states and amplitudes of a confining theory. Both the Pomeron and hadrons have an anomalous color-parity wee-parton component. For the Pomeron the wee-parton component determines that it carries negative color charge parity and that the leading singularity is an isolated Regge pole.

  4. Velocity Dependence of Friction of Confined Hydrocarbons

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.


    We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence of the f......We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence...... of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (∼3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  5. Nematode Locomotion in Unconfined and Confined Fluids

    CERN Document Server

    Bilbao, Alejandro; Vanapalli, Siva; Blawzdziewicz, Jerzy


    The millimeter-long soil-dwelling nematode {\\it C. elegans} propels itself by producing undulations that propagate along its body and turns by assuming highly curved shapes. According to our recent study [PLoS ONE \\textbf{7}, e40121 (2012)] all these postures can be accurately described by a piecewise-harmonic-curvature (PHC) model. We combine this curvature-based description with highly accurate hydrodynamic bead models to evaluate the normalized velocity and turning angles for a worm swimming in an unconfined fluid and in a parallel-wall cell. We find that the worm moves twice as fast and navigates more effectively under a strong confinement, due to the large transverse-to-longitudinal resistance-coefficient ratio resulting from the wall-mediated far-field hydrodynamic coupling between body segments. We also note that the optimal swimming gait is similar to the gait observed for nematodes swimming in high-viscosity fluids. Our bead models allow us to determine the effects of confinement and finite thickness...

  6. Coronal Electron Confinement by Double Layers

    CERN Document Server

    Li, T C; Swisdak, M


    In observations of flare-heated electrons in the solar corona, a longstanding problem is the unexplained prolonged lifetime of the electrons compared to their transit time across the source. This suggests confinement. Recent particle-in-cell (PIC) simulations, which explored the transport of pre-accelerated hot electrons through ambient cold plasma, showed that the formation of a highly localized electrostatic potential drop, in the form of a double layer (DL), significantly inhibited the transport of hot electrons (T.C. Li, J.F. Drake, and M. Swisdak, 2012, ApJ, 757, 20). The effectiveness of confinement by a DL is linked to the strength of the DL as defined by its potential drop. In this work, we investigate the scaling of the DL strength with the hot electron temperature by PIC simulations, and find a linear scaling. We demonstrate that the strength is limited by the formation of parallel shocks. Based on this, we analytically determine the maximum DL strength, and find also a linear scaling with the hot e...

  7. Quantum chromodynamics near the confinement limit

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, C.


    These nine lectures deal at an elementary level with the strong interaction between quarks and its implications for the structure of hadrons. Quarkonium systems are studied as a means for measuring the interquark interaction. This is presumably (part of) the answer a solution to QCD must yield, if it is indeed the correct theory of the strong interactions. Some elements of QCD are reviewed, and metaphors for QCD as a confining theory are introduced. The 1/N expansion is summarized as a way of guessing the consequences of QCD for hadron physics. Lattice gauge theory is developed as a means for going beyond perturbation theory in the solution of QCD. The correspondence between statistical mechanics, quantum mechanics, and field theory is made, and simple spin systems are formulated on the lattice. The lattice analog of local gauge invariance is developed, and analytic methods for solving lattice gauge theory are considered. The strong-coupling expansion indicates the existence of a confining phase, and the renormalization group provides a means for recovering the consequences of continuum field theory. Finally, Monte Carlo simulations of lattice theories give evidence for the phase structure of gauge theories, yield an estimate for the string tension characterizing the interquark force, and provide an approximate description of the quarkonium potential in encouraging good agreement with what is known from experiment.

  8. Holographic quenches in a confined phase (United States)

    Myers, Robert C.; Rozali, Moshe; Way, Benson


    We investigate quenches of holographic theories in a confined phase, where the energy injected is insufficient to reach the deconfined phase. In such quenches, thermalization is not associated with gravitational collapse and the formation of a black hole. Nevertheless, we attempt to characterize the late-time state of this scenario. We check a number of notions of thermalization that do not require horizon formation, and find no evidence for thermalization, or even equilibration, for our chosen parameters and initial states. We find that the post-quench behaviour of both local and nonlocal observables exhibit oscillatory behaviour rather than decaying towards equilibrium. We generally find that the response of the nonlocal observables is smoother than that of the local ones. We discuss mechanisms which generate such smoothing, as well as ‘beats’ which appear in the time-dependence of the nonlocal operators for certain classes of quenches. When tuning the quench parameters such that the smoothing is ineffective, we are able to perform ‘entanglement spectroscopy, recovering the spectrum of the confined phase of the theory from the time dependence of the entanglement entropy, as well as other nonlocal observables.

  9. Polymers confined between two parallel plane walls (United States)

    Hsu, Hsiao-Ping; Grassberger, Peter


    Single three-dimensional polymers confined to a slab, i.e., to the region between two parallel plane walls, are studied by Monte Carlo simulations. They are described by N-step walks on a simple cubic lattice confined to the region 1⩽z⩽D. The simulations cover both regions D≪RF and D≫RF (where RF˜Nν is the Flory radius, with ν≈0.587), as well as the cross-over region in between. Chain lengths are up to N=80 000, slab widths up to D=120. In order to test the analysis program and to check for finite size corrections, we actually studied three different models: (a) ordinary random walks (mimicking Θ polymers); (b) self-avoiding walks; and (c) Domb-Joyce walks with the self-repulsion tuned to the point where finite size corrections for free (unrestricted) chains are minimal. For the simulations we employ the pruned-enriched-Rosenbluth method with Markovian anticipation. In addition to the partition sum (which gives us a direct estimate of the forces exerted onto the walls), we measure the density profiles of monomers and of end points transverse to the slab, and the radial extent of the chain parallel to the walls. All scaling laws and some of the universal amplitude ratios are compared to theoretical predictions.

  10. Design and numerical analysis of microstructured-core octagonal photonic crystal fiber for sensing applications

    Directory of Open Access Journals (Sweden)

    Kawsar Ahmed


    Full Text Available This paper presents an octagonal photonic crystal fiber (O-PCF for liquid sensing, in which both core and cladding are microstructured. Some propagation characteristics of proposed structure have been investigated by using the full vectorial finite element method (FEM. Confinement loss and sensitivity are examined and compared with varying number of rings, core diameter, diameter of air holes in cladding ring and pitch. It is found that sensitivity is increased for the increment pitch value, air filling ratio, core diameter, inner ring diameter as well as number of rings. At the same time confinement loss is significantly decreased. It is also found that the increment of pitch by keeping the same air filling ratio increases the sensitivity and loss. Investigating the effects of different parameters, an O-PCF structure is designed which has a significantly higher relative sensitivity and lower confinement loss.

  11. Multi-core Microprocessors

    Indian Academy of Sciences (India)

    programming and computer fundamentals. His current research interests are parallel computing and history of computing. Multi-core microprocessor is an interconnected set of inde- pendent processors called cores integrated on a single sili- con chip. These processing cores communicate and cooperate with one another ...

  12. Core Competence and Education. (United States)

    Holmes, Gary; Hooper, Nick


    Outlines the concept of core competence and applies it to postcompulsory education in the United Kingdom. Adopts an educational perspective that suggests accreditation as the core competence of universities. This economic approach suggests that the market trend toward lifetime learning might best be met by institutions developing a core competence…

  13. Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums. (United States)

    Glenzer, S H; MacGowan, B J; Meezan, N B; Adams, P A; Alfonso, J B; Alger, E T; Alherz, Z; Alvarez, L F; Alvarez, S S; Amick, P V; Andersson, K S; Andrews, S D; Antonini, G J; Arnold, P A; Atkinson, D P; Auyang, L; Azevedo, S G; Balaoing, B N M; Baltz, J A; Barbosa, F; Bardsley, G W; Barker, D A; Barnes, A I; Baron, A; Beeler, R G; Beeman, B V; Belk, L R; Bell, J C; Bell, P M; Berger, R L; Bergonia, M A; Bernardez, L J; Berzins, L V; Bettenhausen, R C; Bezerides, L; Bhandarkar, S D; Bishop, C L; Bond, E J; Bopp, D R; Borgman, J A; Bower, J R; Bowers, G A; Bowers, M W; Boyle, D T; Bradley, D K; Bragg, J L; Braucht, J; Brinkerhoff, D L; Browning, D F; Brunton, G K; Burkhart, S C; Burns, S R; Burns, K E; Burr, B; Burrows, L M; Butlin, R K; Cahayag, N J; Callahan, D A; Cardinale, P S; Carey, R W; Carlson, J W; Casey, A D; Castro, C; Celeste, J R; Chakicherla, A Y; Chambers, F W; Chan, C; Chandrasekaran, H; Chang, C; Chapman, R F; Charron, K; Chen, Y; Christensen, M J; Churby, A J; Clancy, T J; Cline, B D; Clowdus, L C; Cocherell, D G; Coffield, F E; Cohen, S J; Costa, R L; Cox, J R; Curnow, G M; Dailey, M J; Danforth, P M; Darbee, R; Datte, P S; Davis, J A; Deis, G A; Demaret, R D; Dewald, E L; Di Nicola, P; Di Nicola, J M; Divol, L; Dixit, S; Dobson, D B; Doppner, T; Driscoll, J D; Dugorepec, J; Duncan, J J; Dupuy, P C; Dzenitis, E G; Eckart, M J; Edson, S L; Edwards, G J; Edwards, M J; Edwards, O D; Edwards, P W; Ellefson, J C; Ellerbee, C H; Erbert, G V; Estes, C M; Fabyan, W J; Fallejo, R N; Fedorov, M; Felker, B; Fink, J T; Finney, M D; Finnie, L F; Fischer, M J; Fisher, J M; Fishler, B T; Florio, J W; Forsman, A; Foxworthy, C B; Franks, R M; Frazier, T; Frieder, G; Fung, T; Gawinski, G N; Gibson, C R; Giraldez, E; Glenn, S M; Golick, B P; Gonzales, H; Gonzales, S A; Gonzalez, M J; Griffin, K L; Grippen, J; Gross, S M; Gschweng, P H; Gururangan, G; Gu, K; Haan, S W; Hahn, S R; Haid, B J; Hamblen, J E; Hammel, B A; Hamza, A V; Hardy, D L; Hart, D R; Hartley, R G; Haynam, C A; Heestand, G M; Hermann, M R; Hermes, G L; Hey, D S; Hibbard, R L; Hicks, D G; Hinkel, D E; Hipple, D L; Hitchcock, J D; Hodtwalker, D L; Holder, J P; Hollis, J D; Holtmeier, G M; Huber, S R; Huey, A W; Hulsey, D N; Hunter, S L; Huppler, T R; Hutton, M S; Izumi, N; Jackson, J L; Jackson, M A; Jancaitis, K S; Jedlovec, D R; Johnson, B; Johnson, M C; Johnson, T; Johnston, M P; Jones, O S; Kalantar, D H; Kamperschroer, J H; Kauffman, R L; Keating, G A; Kegelmeyer, L M; Kenitzer, S L; Kimbrough, J R; King, K; Kirkwood, R K; Klingmann, J L; Knittel, K M; Kohut, T R; Koka, K G; Kramer, S W; Krammen, J E; Krauter, K G; Krauter, G W; Krieger, E K; Kroll, J J; La Fortune, K N; Lagin, L J; Lakamsani, V K; Landen, O L; Lane, S W; Langdon, A B; Langer, S H; Lao, N; Larson, D W; Latray, D; Lau, G T; Le Pape, S; Lechleiter, B L; Lee, Y; Lee, T L; Li, J; Liebman, J A; Lindl, J D; Locke, S F; Loey, H K; London, R A; Lopez, F J; Lord, D M; Lowe-Webb, R R; Lown, J G; Ludwigsen, A P; Lum, N W; Lyons, R R; Ma, T; MacKinnon, A J; Magat, M D; Maloy, D T; Malsbury, T N; Markham, G; Marquez, R M; Marsh, A A; Marshall, C D; Marshall, S R; Maslennikov, I L; Mathisen, D G; Mauger, G J; Mauvais, M -Y; McBride, J A; McCarville, T; McCloud, J B; McGrew, A; McHale, B; MacPhee, A G; Meeker, J F; Merill, J S; Mertens, E P; Michel, P A; Miller, M G; Mills, T; Milovich, J L; Miramontes, R; Montesanti, R C; Montoya, M M; Moody, J; Moody, J D; Moreno, K A; Morris, J; Morriston, K M; Nelson, J R; Neto, M; Neumann, J D; Ng, E; Ngo, Q M; Olejniczak, B L; Olson, R E; Orsi, N L; Owens, M W; Padilla, E H; Pannell, T M; Parham, T G; Patterson, R W; Pavel, G; Prasad, R R; Pendlton, D; Penko, F A; Pepmeier, B L; Petersen, D E; Phillips, T W; Pigg, D; Piston, K W; Pletcher, K D; Powell, C L; Radousky, H B; Raimondi, B S; Ralph, J E; Rampke, R L; Reed, R K; Reid, W A; Rekow, V V; Reynolds, J L; Rhodes, J J; Richardson, M J; Rinnert, R J; Riordan, B P; Rivenes, A S; Rivera, A T; Roberts, C J; Robinson, J A; Robinson, R B; Robison, S R; Rodriguez, O R; Rogers, S P; Rosen, M D; Ross, G F; Runkel, M; Runtal, A S; Sacks, R A; Sailors, S F; Salmon, J T; Salmonson, J D; Saunders, R L; Schaffer, J R; Schindler, T M; Schmitt, M J; Schneider, M B; Segraves, K S; Shaw, M J; Sheldrick, M E; Shelton, R T; Shiflett, M K; Shiromizu, S J; Shor, M; Silva, L L; Silva, S A; Skulina, K M; Smauley, D A; Smith, B E; Smith, L K; Solomon, A L; Sommer, S; Soto, J G; Spafford, N I; Speck, D E; Springer, P T; Stadermann, M; Stanley, F; Stone, T G; Stout, E A; Stratton, P L; Strausser, R J; Suter, L J; Sweet, W; Swisher, M F; Tappero, J D; Tassano, J B; Taylor, J S; Tekle, E A; Thai, C; Thomas, C A; Thomas, A; Throop, A L; Tietbohl, G L; Tillman, J M; Town, R P J; Townsend, S L; Tribbey, K L; Trummer, D; Truong, J; Vaher, J; Valadez, M; Van Arsdall, P; Van Prooyen, A J; Vergel de Dios, E O; Vergino, M D; Vernon, S P; Vickers, J L; Villanueva, G T; Vitalich, M A; Vonhof, S A; Wade, F E; Wallace, R J; Warren, C T; Warrick, A L; Watkins, J; Weaver, S; Wegner, P J; Weingart, M A; Wen, J; White, K S; Whitman, P K; Widmann, K; Widmayer, C C; Wilhelmsen, K; Williams, E A; Williams, W H; Willis, L; Wilson, E F; Wilson, B A; Witte, M C; Work, K; Yang, P S; Young, B K; Youngblood, K P; Zacharias, R A; Zaleski, T; Zapata, P G; Zhang, H; Zielinski, J S; Kline, J L; Kyrala, G A; Niemann, C; Kilkenny, J D; Nikroo, A; Van Wonterghem, B M; Atherton, L J; Moses, E I


    We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core. © 2011 American Physical Society

  14. Time-dependent nuclear measurements of mix in inertial confinement fusion. (United States)

    Rygg, J R; Frenje, J A; Li, C K; Séguin, F H; Petrasso, R D; Glebov, V Yu; Meyerhofer, D D; Sangster, T C; Stoeckl, C


    The first time-dependent nuclear measurements of turbulent mix in inertial confinement fusion have been obtained. Implosions of spherical deuterated-plastic shells filled with pure 3He gas require atomic-scale mixing of the shell and gas for the D-3He nuclear reaction to proceed. The time necessary for Rayleigh-Taylor (RT) growth to induce mix delays peak nuclear production time, compared to equivalent capsules filled with a D2-3He mixture, by 75+/-30 ps, equal to half the nuclear burn duration. These observations indicate the likelihood of atomic mix at the tips of core-penetrating RT spikes.

  15. Earth Regime Network Evolution Study (ERNESt) (United States)

    Menrad, Bob


    Speaker and Presenter at the Lincoln Laboratory Communications Workshop on April 5, 2016 at the Massachusetts Institute of Technology Lincoln Laboratory in Lexington, MA. A visual presentation titled Earth Regimes Network Evolution Study (ERNESt).

  16. Policy Regime Juxtaposition in Latin America

    Directory of Open Access Journals (Sweden)

    Kent Eaton


    Full Text Available This article has three main objectives, each in the spirit of broadening the study of subnational politics to include the juxtaposition of policy regimes and not just political regimes. First, it identifies the causes that help explain why we are seeing more territorial heterogeneity within countries in terms of the pursuit of ideologically disparate development models at different levels of government. Second, the article assesses the importance of this trend by analyzing the chief advantages and disadvantages of policy regime juxtaposition. Third, I turn to the question of why subnational officials are able to defend ideologically deviant policy regimes in some cases, but not in others. Based on the Bolivian, Ecuadorian, and Peruvian cases, my argument emphasizes the importance of two key factors: capacity and coalitions.

  17. Stochastic dynamical models for ecological regime shifts

    DEFF Research Database (Denmark)

    Møller, Jan Kloppenborg; Carstensen, Jacob; Madsen, Henrik

    Ecosystems are influenced by a variety of known and unknown drivers. Unknown drivers should be modeled as noise and it is therefore important to analyze how noise influences the deterministic skeleton of system equations. The deterministic skeleton of stochastic dynamical models contains the phys...... definition and stability of regimes become less subtle. Ecological regime shifts and their modeling must be viewed in a probabilistic manner, particularly if such model results are to be used in ecosystem management....

  18. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao


    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  19. Theoretical flow regime diagrams for the AGCE (United States)

    Fowlis, W. W.; Miller, T. L.; Roberts, G. O.; Kopecky, K. J.


    The major criterion for the design of the Atmospheric General Circulation Experiment is that it be possible to realize strong baroclinic instability in the apparatus. A spherical annulus configuration which allows only steady basic state flows was chosen for the first set of stability analyses. Baroclinic instability was found for this configuration and few results suggest a regime diagram very different from the cylindrical annulus regime diagram.

  20. Preferential tax regimes with asymmetric countries


    Bucovetsky, Sam; Haufler, Andreas


    Current policy initiatives taken by the EU and the OECD aim at abolishing preferential corporate tax regimes. This note extends Keen's (2001) analysis of symmetric capital tax competition under preferential (or discriminatory) and non-discriminatory tax regimes to allow for countries of different size. Even though size asymmetries imply a redistribution of tax revenue from the larger to the smaller country, a non-discrimination policy is found to have similar effects as in the symmetric model...

  1. Light and gas confinement in hollow-core photonic crystal fibre based photonic microcells

    DEFF Research Database (Denmark)

    Benabid, F.; Roberts, John; Couny, F.


    optical waveguide guidance. For the second type of fibre, which can guide over a broad wavelength range, we examine the nature of the inhibited coupling. We describe a technique for the fabrication of photonic microcells that can accommodate vacuum pressures, and we finish by showing the latest results...

  2. Piecewise Tendency Diagnosis of Weather Regime Transitions. (United States)

    Evans, Katherine J.; Black, Robert X.


    Piecewise tendency diagnosis (PTD) is extended and employed to study the dynamics of weather regime transitions. Originally developed for adiabatic and inviscid quasigeostrophic flow on a beta plane, PTD partitions local geopotential tendencies into a linear combination of dynamically meaningful source terms within a potential vorticity (PV) framework. Here PTD is amended to account for spherical geometry, diabatic heating, and ageostrophic processes, and is then used to identify the primary mechanisms responsible for Northern Hemisphere weather regime transitions.Height tendency patterns obtained by summing the contributions of individual PTD forcing terms correspond very well to actual height tendencies. Composite PTD analyses reveal that linear PV advections provide the largest dynamical forcing for the weather regime development over the North Pacific. Specifically, linear baroclinic growth provides the primary forcing while barotropic deformation of PV anomalies provides a secondary contribution. North Atlantic anticyclonic anomalies develop from the combined effects of barotropic deformation, baroclinic growth, and nonlinear eddy feedback. The Atlantic cyclonic cases develop primarily from barotropic deformation and nonlinear eddy feedback. All four weather regime types decay primarily due to enhanced wave energy propagation away from the primary circulation anomaly. In some cases, regime decay is aided by decreasing positive contributions from barotropic deformation as the circulation anomaly attains a deformed horizontal shape. The current results 1) provide quantitative measures of the primary mechanisms responsible for weather regime transition and 2) demonstrate the utility of the extended PTD as a concise diagnostic paradigm for studying large-scale dynamical processes in the midlatitude troposphere.

  3. State Structure and Political Regime Structure

    Directory of Open Access Journals (Sweden)

    Paul – Iulian Nedelcu


    Full Text Available The political regime is the concrete form of organization and functioning of political system andtherefore, the regime means the concrete way of organize, institutionalize and function a political systemand of the exercise of political power by a social-political force in a social community or global socialistem. The political regime is not limited to institutions and state bodies, but it covers the entire politicalsystem. Form of expression in social practice plan is the result of balance of forces between classes ofcitizens, organizations, between them and civil society and politics.Designates the concrete form ofgovernment formation and organization, of state bodies, in aspect of their characteristics and principles, therelations between them and other state bodies, and also as the relationship between them and otherinstitutionalized forms of political systems. Instead, the political regime is an explicit realization ofaxiological operations, a specific hierarchy of values, in general and political values, in particular. Even ifsome elements of the political regime overlap to some extent and in some respects, those of form orstructure of guvernamnt state, thus they dissolve his identity, distinct quality of being specific traits of thepolitical regime.

  4. Is it possible that MHD instability triggers a transition into the improved confinement regime of toroidal plasmas? (United States)

    Shchepetov, S. V.; Vasilkov, D. G.


    Analyzing the experimental data from L-2M stellarator and performing appropriate theoretical analysis, the authors affirmatively answer the question raised in the title of the article. The external peeling mode is proposed as the instability triggering the transition. Peeling mode stability in magnetic-hill Mercierstable plasmas is analyzed analytically. It is shown that correctly taking into account vacuum region forbids internal peeling modes, while the external peeling mode has a threshold with respect to the plasma pressure gradient. Calculations and experimental data are in reasonable agreement.

  5. Highly birefringent elliptical core photonic crystal fiber for terahertz application (United States)

    Sultana, Jakeya; Islam, Md. Saiful; Faisal, Mohammad; Islam, Mohammad Rakibul; Ng, Brian W.-H.; Ebendorff-Heidepriem, Heike; Abbott, Derek


    We present a novel strategy for designing a highly birefringent photonic crystal fiber (PCF) with near zero flattened dispersion properties by applying elliptical air holes in the core area. The elliptical structure of the air holes in the porous-core region introduces asymmetry between x and y polarization modes, which consequently offers ultra-high birefringence. Also the compact geometry of the conventional hexagonal structure in the cladding confines most of the useful power. The optical properties including birefringence, dispersion, confinement loss, effective material loss (EML) and single modeness of the fiber are investigated using a full-vector finite element method. Simulation results show an ultra-high birefringence of 0 . 086 ultra-flattened near zero dispersion of 0 . 53 ± 0 . 07 ps/THz/cm in a broad frequency range. The practical implementation of the proposed fiber is feasible using existing fabrication technology and is applicable to the areas of terahertz sensing and polarization maintaining systems.

  6. Introduction and Overview of China’s Pilot Training Regime

    Directory of Open Access Journals (Sweden)

    Weifeng Li


    Full Text Available When operating in confined waters such as ports, channels and canals, the ship’s master may not be familiar with the specific and up-to-date navigating conditions such as wind, current and tide. In this case, the master must rely on the knowledge and experience of local experts, the seaport and river pilots, to ensure the safety of the ship, crew and environment. This paper provides an overview of the initial and periodic training required by pilots directed by the China Maritime Safety Administration in accordance with IMO’s A.960 “Recommendation on Training and Certification and Operational Procedure Maritime Pilot Other Than Deep-Sea Pilot” and China’s pilot training requirements. The paper then goes into details describing how pilot training is implemented in Dalian Maritime University (DMU, taking into account the course setting, class hour arrangement, theory and practical class distribution of different class pilots, as well as examining the equipment requirements, trainer’s qualification, and trainee’s seagoing experiences. Based on the results of the China’s pilot training regime, recommendations will be made not only for improving China’s pilot training program, but also where DMU’s best practices may be implemented at other institutions engaged in pilot professional development.

  7. Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

    DEFF Research Database (Denmark)

    Vienne, Guillaume; Xu, Yong; Jakobsen, Christian


    We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding...

  8. What confines the rings of Saturn? (United States)

    Tajeddine, Radwan; Nicholson, Philip D.; El Moutamid, Maryame; Longaretti, Pierre-Yves; Burns, Joseph A.


    The viscous spreading of planetary rings is believed to be counteracted by satellite torques, either through an individual resonance or through overlapping resonances (when the satellite is close to the ring edge). For the A ring of Saturn, it has been commonly believed that the satellite Janus alone can prevent the ring from spreading via its 7:6 Lindblad resonance. We discuss this common misconception and show that, in reality, the A ring is confined by the contributions from the group of satellites Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus, and Mimas, whose resonances gradually decrease the angular momentum flux transported outward through the ring via density and bending waves. We further argue that this decrease in angular momentum flux occurs through the mechanism of ‘flux reversal’.We find that the Janus 7:6 torque is relatively feeble, as is the comparable torque of the nearby small satellite Atlas, each amounting to less than one-tenth of the angular momentum transport carried by the A ring. But the cumulative torques of the many other satellite resonances in the A ring sufficiently reduce the angular momentum flux through the rings so that the torques due to Janus and Atlas are effective in confining the outer edge of the ring.Furthermore, we use the magnitude of the satellites’ resonance torques to estimate the effective viscosity profile across the A ring, showing that it decreases from ~50 cm2 s-1 at the inner edge to less than ~11 cm2 s-1 at the outer edge. The gradual estimated decrease of the angular momentum flux and effective viscosity are roughly consistent with results obtained by balancing the shepherding torques from Pan and Daphnis with the viscous torque at the edges of the Encke and Keeler gaps, as well as the edge of the A ring.On the other hand, the Mimas 2:1 Lindblad resonance alone seems to be capable of confining the edge of the B ring, and contrary to the situation in the A ring, we show that the effective viscosity

  9. Core stability exercise principles. (United States)

    Akuthota, Venu; Ferreiro, Andrea; Moore, Tamara; Fredericson, Michael


    Core stability is essential for proper load balance within the spine, pelvis, and kinetic chain. The so-called core is the group of trunk muscles that surround the spine and abdominal viscera. Abdominal, gluteal, hip girdle, paraspinal, and other muscles work in concert to provide spinal stability. Core stability and its motor control have been shown to be imperative for initiation of functional limb movements, as needed in athletics. Sports medicine practitioners use core strengthening techniques to improve performance and prevent injury. Core strengthening, often called lumbar stabilization, also has been used as a therapeutic exercise treatment regimen for low back pain conditions. This article summarizes the anatomy of the core, the progression of core strengthening, the available evidence for its theoretical construct, and its efficacy in musculoskeletal conditions.

  10. Duality and Confinement in Massive Antisymmetric Tensor Gauge Theories

    CERN Document Server

    Diamantini, M Cristina


    We extend the duality between massive and topologically massive antisymmetric tensor gauge theories in arbitrary space-time dimensions to include topological defects. We show explicitly that the condensation of these defects leads, in 4 dimensions, to confinement of electric strings in the two dual models. The dual phase, in which magnetic strings are confined is absent. The presence of the confinement phase explicitely found in the 4-dimensional case, is generalized, using duality arguments, to arbitrary space-time dimensions.


    Energy Technology Data Exchange (ETDEWEB)

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell


    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate

  12. Generalized Lawson Criteria for Inertial Confinement Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tipton, Robert E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    The Lawson Criterion was proposed by John D. Lawson in 1955 as a general measure of the conditions necessary for a magnetic fusion device to reach thermonuclear ignition. Over the years, similar ignition criteria have been proposed which would be suitable for Inertial Confinement Fusion (ICF) designs. This paper will compare and contrast several ICF ignition criteria based on Lawson’s original ideas. Both analytical and numerical results will be presented which will demonstrate that although the various criteria differ in some details, they are closely related and perform similarly as ignition criteria. A simple approximation will also be presented which allows the inference of each ignition parameter directly from the measured data taken on most shots fired at the National Ignition Facility (NIF) with a minimum reliance on computer simulations. Evidence will be presented which indicates that the experimentally inferred ignition parameters on the best NIF shots are very close to the ignition threshold.

  13. Ultra-Compact Electrostatic Confinement Fusion Device (United States)

    Young, Garrett


    A unique, linear dual-beam configuration with an internal volume of 144 cc was simulated and operated. Deuteron ion paths were simulated using Mathematica and the electric field distribution was optimized relative to convergence density, potential well efficiency, and confinement time. The resulting cathode design is a departure from conventional systems, with gradual conical surfaces. The simulated trajectories correlated well to the observed operation, evidenced by two principle factors. First, the high transparency of the cathode due to the focused beams allowed for >1 kW operation without duration-limiting temperature rise. Second, when compared to inertial electrostatic configurations, the constructed device achieved record steady-state D-D fusion rates per internal volume including 3.7E +4 fusions/sec/cc at 52 kV applied potential and 28 mTorr operating pressure.

  14. Morphogenesis of filaments growing in flexible confinements (United States)

    Vetter, R.; Wittel, F. K.; Herrmann, H. J.


    Space-saving design is a requirement that is encountered in biological systems and the development of modern technological devices alike. Many living organisms dynamically pack their polymer chains, filaments or membranes inside deformable vesicles or soft tissue-like cell walls, chorions and buds. Surprisingly little is known about morphogenesis due to growth in flexible confinements—perhaps owing to the daunting complexity lying in the nonlinear feedback between packed material and expandable cavity. Here we show by experiments and simulations how geometric and material properties lead to a plethora of morphologies when elastic filaments are growing far beyond the equilibrium size of a flexible thin sheet they are confined in. Depending on friction, sheet flexibility and thickness, we identify four distinct morphological phases emerging from bifurcation and present the corresponding phase diagram. Four order parameters quantifying the transitions between these phases are proposed.

  15. A new discipline: Confined Areas Medicine

    Directory of Open Access Journals (Sweden)

    Stefano Agostinis


    Full Text Available The Confined Areas Medicine is a new discipline devoted to a specific branch of the components of emergency services. In it convey the characteristics typical of behavioral intervention in hostile area peculiar of the National Fire Corps and the National Speleological and Alpine Corps. While not considering the natural events that cause the collapse of housing the Italian case reported in the last fifty years about two hundred structural collapses that are charged over a thousand deaths (source: ISTAT 2006. Analysis of the documents accessible to the public today we can say without fear of denials, that 25% of these deaths are due to relief late or ineffective treatment on the spot. In fact, the NFPA (National Fire Protection Association claims that 10% of victims trapped under the rubble can be saved with a location and an early recovery, which can significantly increase this percentage with the health care stabilization directly at the place of discovery.

  16. Velocity dependence of friction of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.


    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate, and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional...... shear stress for both cases. In our simulations, the polymer films are very thin (approx. 3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  17. Modeling collective cell migration in geometric confinement (United States)

    Tarle, Victoria; Gauquelin, Estelle; Vedula, S. R. K.; D'Alessandro, Joseph; Lim, C. T.; Ladoux, Benoit; Gov, Nir S.


    Monolayer expansion has generated great interest as a model system to study collective cell migration. During such an expansion the culture front often develops ‘fingers’, which we have recently modeled using a proposed feedback between the curvature of the monolayer’s leading edge and the outward motility of the edge cells. We show that this model is able to explain the puzzling observed increase of collective cellular migration speed of a monolayer expanding into thin stripes, as well as describe the behavior within different confining geometries that were recently observed in experiments. These comparisons give support to the model and emphasize the role played by the edge cells and the edge shape during collective cell motion.

  18. Confining standing waves in optical corrals. (United States)

    Babayan, Yelizaveta; McMahon, Jeffrey M; Li, Shuzhou; Gray, Stephen K; Schatz, George C; Odom, Teri W


    Near-field scanning optical microscopy images of solid wall, circular, and elliptical microscale corrals show standing wave patterns confined inside the structures with a wavelength close to that of the incident light. The patterns inside the corrals can be tuned by changing the size and material of the walls, the wavelength of incident light, and polarization direction for elliptical corrals. Finite-difference time-domain calculations of the corral structures agree with the experimental observations and reveal that the electric and magnetic field intensities are out of phase inside the corral. A theoretical modal analysis indicates that the fields inside the corrals can be attributed to p- and s-polarized waveguide modes, and that the superposition of the propagating and evanescent modes can explain the phase differences between the fields. These experimental and theoretical results demonstrate that electromagnetic fields on a dielectric surface can be controlled in a predictable manner.

  19. Topological Spin Textures in Confined Geometries (United States)

    Zang, Jiadong

    The magnetic skyrmion is a nanostructured spin texture stabilized by the spin-orbital coupling. Its nontrivial topology enables unique dynamical property and thermal stability, which give out promise on future magnetic memory devise. However, to enable its applications, it is essential to understand the skyrmion properties in confined geometries and tackle key challenges including the creation and detection of skyrmions, preferably without magnetic fields. In this talk, I will present our recent theory-experiment collaboration results, covering studies of skyrmions in nanoribbon, nanodisk, and nanowires. Zero field skyrmions and their polarization switch will be discussed. New skyrmion materials and new topological textures in helimagnet heterostructures will be presented. This work is supported by the Grant DE-SC0016424 funded by the U.S. Department of Energy, Office of Science.

  20. Dancing disclinations in confined active nematics (United States)

    Shendruk, Tyler N.; Doostmohammadi, Amin; Thijssen, Kristian; Yeomans, Julia M.

    The spontaneous emergence of collective flows is a generic property of active fluids and often leads to chaotic flow patterns characterised by swirls, jets, and topological disclinations in their orientation field. However, the ability to achieve structured flows and ordered disclinations is of particular importance in the design and control of active systems. By confining an active nematic fluid within a channel, we find a regular motion of disclinations, in conjunction with a well defined and dynamic vortex lattice. As pairs of moving disclinations travel through the channel, they continually exchange partners producing a dynamic ordered state, reminiscent of Ceilidh dancing. We anticipate that this biomimetic ability to self-assemble organised topological disclinations and dynamically structured flow fields in engineered geometries will pave the road towards establishing new active topological microfluidic devices.

  1. Dancing droplets: Contact angle, drag, and confinement (United States)

    Benusiglio, Adrien; Cira, Nate; Prakash, Manu


    When deposited on a clean glass slide, a mixture of water and propylene glycol forms a droplet of given contact angle, when both pure liquids spread. (Cira, Benusiglio, Prakash: Nature, 2015). The droplet is stabilized by a gradient of surface tension due to evaporation that induces a Marangoni flow from the border to the apex of the droplets. The apparent contact angle of the droplets depends on both their composition and the external humidity as captured by simple models. These droplets present remarkable properties such as lack of a large pinning force. We discuss the drag on these droplets as a function of various parameters. We show theoretical and experimental results of how various confinement geometries change the vapor gradient and the dynamics of droplet attraction.

  2. The theory of toroidally confined plasmas

    CERN Document Server

    White, Roscoe B


    This graduate level textbook develops the theory of magnetically confined plasma, with the aim of bringing the reader to the level of current research in the field of thermonuclear fusion. It begins with the basic concepts of magnetic field description, plasma equilibria and stability, and goes on to derive the equations for guiding center particle motion in an equilibrium field. Topics include linear and nonlinear ideal and resistive modes and particle transport. It is of use to workers in the field of fusion both for its wide-ranging account of tokamak physics and as a kind of handbook or formulary. This edition has been extended in a number of ways. The material on mode-particle interactions has been reformulated and much new information added, including methodology for Monte Carlo implementation of mode destabilization. These results give explicit means of carrying out mode destabilization analysis, in particular for the dangerous fishbone mode. A new chapter on cyclotron motion in toroidal geometry has ...

  3. Asymmetric expectation effects of regime shifts in monetary policy


    Zheng Liu; Daniel F. Waggoner; Tao Zha


    This paper addresses two substantive issues: (1) Does the magnitude of the expectation effect of regime switching in monetary policy depend on a particular policy regime? (2) Under which regime is the expectation effect quantitatively important? Using two canonical DSGE models, we show that there exists asymmetry in the expectation effect across regimes. The expectation effect under the dovish policy regime is quantitatively more important than that under the hawkish regime. These results sug...

  4. Structure of charged polymer chains in confined geometry.

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, E. P.; Auvray, L.; Lal, J.


    The intra- and interchain structure of sodium poly(styrenesulphonate) when free and when confined in contrast matched porous Vycor has been investigated by SANS. When confined, a peak is observed whose intensity increases with molecular weight and the 1/q scattering region is extended compared to the bulk. We infer that the chains are sufficiently extended, under the influence of confinement, to highlight the large scale disordered structure of Vycor. The asymptotic behavior of the observed interchain structure factor is = 1/q{sup 2} and = 1/q for free and confined chains respectively.

  5. Cancer cell motility: lessons from migration in confined spaces (United States)

    Paul, Colin D.; Mistriotis, Panagiotis; Konstantopoulos, Konstantinos


    Time-lapse, deep-tissue imaging made possible by advances in intravital microscopy has demonstrated the importance of tumour cell migration through confining tracks in vivo. These tracks may either be endogenous features of tissues or be created by tumour or tumour-associated cells. Importantly, migration mechanisms through confining microenvironments are not predicted by 2D migration assays. Engineered in vitro models have been used to delineate the mechanisms of cell motility through confining spaces encountered in vivo. Understanding cancer cell locomotion through physiologically relevant confining tracks could be useful in developing therapeutic strategies to combat metastasis. PMID:27909339

  6. The cruel and unusual phenomenology of solitary confinement. (United States)

    Gallagher, Shaun


    What happens when subjects are deprived of intersubjective contact? This paper looks closely at the phenomenology and psychology of one example of that deprivation: solitary confinement. It also puts the phenomenology and psychology of solitary confinement to use in the legal context. Not only is there no consensus on whether solitary confinement is a "cruel and unusual punishment," there is no consensus on the definition of the term "cruel" in the use of that legal phrase. I argue that we can find a moral consensus on the meaning of "cruelty" by looking specifically at the phenomenology and psychology of solitary confinement.

  7. Core-shell hydrogel microcapsules for improved islets encapsulation. (United States)

    Ma, Minglin; Chiu, Alan; Sahay, Gaurav; Doloff, Joshua C; Dholakia, Nimit; Thakrar, Raj; Cohen, Joshua; Vegas, Arturo; Chen, Delai; Bratlie, Kaitlin M; Dang, Tram; York, Roger L; Hollister-Lock, Jennifer; Weir, Gordon C; Anderson, Daniel G


    Islets microencapsulation holds great promise to treat type 1 diabetes. Currently used alginate microcapsules often have islets protruding outside capsules, leading to inadequate immuno-protection. A novel design of microcapsules with core-shell structures using a two-fluid co-axial electro-jetting is reported. Improved encapsulation and diabetes correction is achieved in a single step by simply confining the islets in the core region of the capsules. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Isotropic-to-nematic phase transition of liquid crystals confined in nanoemulsion droplets (United States)

    Bono, S.; Takanishi, Y.; Yamamoto, J.


    We fabricated liquid crystalline nanoemulsions (LCNEs) by introducing low molecular weight liquid crystals (LMWLCs) into the core of nanoemulsions, and investigated the phase transition behavior of LMWLCs in the core part with the various weight ratios of LMWLCs to surfactants. The polarized dynamic light scattering measurement was performed to estimate the radii of LCNEs, and it is found that their radii can be controlled by the weight ratio of LMLCs to surfactant polymers. In the depolarized light scattering, it was revealed that the order of the isotropic-nematic phase transition behavior changes from the first order to biased second order with decreasing radius of LCNEs because of the three-dimensional confinement effect surrounded by an anchoring surface.

  9. A suspended core nanofiber with unprecedented large diameter ratio of holey region to core. (United States)

    Liao, Meisong; Chaudhari, Chitrarekha; Yan, Xin; Qin, Guanshi; Kito, Chihiro; Suzuki, Takenobu; Ohishi, Yasutake


    For a suspended core nanofiber, the holey region is expected to be as large as possible to propagate the light at wavelengths as long as possible. Additionally, a large holey region is significant for its applications in sensors. However, the fabrication of nanofiber with large holey region is still a challenge so far. In this paper a method, which involves pumping positive pressure of nitrogen gas in both the cane fabrication and fiber-drawing processes, was proposed. A suspended core nanofiber, with a core diameter of around 480 nm and an unprecedented diameter ratio of holey region to core (DRHC) of at least 62, was fabricated in the length of several hundred meters. Owing to the large holey region, the confinement loss of the suspended core nanofiber is insignificant when the wavelength of light propagated in it is 1700 nm. For this fabrication technique, the nanowire length, fabrication efficiency, and the uniformity in the diameter are much superior to those of the nanowires fabricated in other ways. Finally, single mode third harmonic generation was observed by this nanofiber under the pump of a 1557 nm femtosecond fiber laser. This work shows the prospect of fabrication of nanostructured waveguide in glass materials by an inflation technique.

  10. Biosafety regulatory regimes in East and Central Africa

    African Journals Online (AJOL)


    , P.O. Box 35179, Dar es Salaam, ..... establish and update a register of experts in .... biological containment/confinement are stated in the TZ biosafety guidelines. Biosafety laboratory (preferably level 2) for basic research, confined field trials ...

  11. Cores, Filaments, and Bundles: Hierarchical core formation in the B213 filament in Taurus (United States)

    Hacar, Alvaro; Tafalla, Mario; Kauffmann, Jens; Kovacs, Attila


    Characterizing the dense core formation in filaments is a critical step for our understanding of the star formation process within molecular clouds. Using different molecular tracers to study the gas kinematics at different scales and density regimes, we have investigated the dense core formation in the B213/L1495 filament in Taurus, one of the most prominent structures identified in nearby clouds (see Hacar et al 2013, A&A, 554, A55). Our analysis of its internal kinematics demonstrates that this filament is actually a bundle of 35 velocity-coherent filaments, typically with lengths of ˜ 0.5 pc and oscillatory-like and sonic velocity field, each of them exhibiting linear masses close to the expected mass for a filament in hydrostatic equilibrium. Among them, only a small fraction of these filaments (˜1/4) are "fertile" and efficiently fragment forming all the cores identified within this region, while most of them (˜3/4) do not form cores and remain "sterile". Our observations then suggest that core formation in Taurus occurs in two steps. First, 0.5 pc-long velocity-coherent filaments condense out of the cloud gas, probably as a result of the turbulent cascade. After that, the dense cores condense quasi-statically in only those "fertile" filaments that have accumulated enough mass to became gravitational unstable, inheriting their kinematic properties. The formation of these velocity-coherent filaments appears therefore as a critical step on the star formation process being the first subsonic structures formed out of the turbulent regime that dominates the cloud dynamics at large scales.

  12. The Green Bank Ammonia Survey: Dense Cores under Pressure in Orion A (United States)

    Kirk, Helen; Friesen, Rachel K.; Pineda, Jaime E.; Rosolowsky, Erik; Offner, Stella S. R.; Matzner, Christopher D.; Myers, Philip C.; Di Francesco, James; Caselli, Paola; Alves, Felipe O.; Chacón-Tanarro, Ana; Chen, How-Huan; Chun-Yuan Chen, Michael; Keown, Jared; Punanova, Anna; Seo, Young Min; Shirley, Yancy; Ginsburg, Adam; Hall, Christine; Singh, Ayushi; Arce, Héctor G.; Goodman, Alyssa A.; Martin, Peter; Redaelli, Elena


    We use data on gas temperature and velocity dispersion from the Green Bank Ammonia Survey and core masses and sizes from the James Clerk Maxwell Telescope Gould Belt Survey to estimate the virial states of dense cores within the Orion A molecular cloud. Surprisingly, we find that almost none of the dense cores are sufficiently massive to be bound when considering only the balance between self-gravity and the thermal and non-thermal motions present in the dense gas. Including the additional pressure binding imposed by the weight of the ambient molecular cloud material and additional smaller pressure terms, however, suggests that most of the dense cores are pressure-confined.

  13. Kinetic transport in a magnetically confined and flux-constrained fusion plasma; Transport cinetique dans un plasma de fusion magnetique a flux force

    Energy Technology Data Exchange (ETDEWEB)

    Darmet, G


    This work deals with the kinetic transport in a fusion plasma magnetically confined and flux-constrained. The author proposes a new interpretation of the dynamics of zonal flows. The model that has been studied is a gyrokinetic model reduced to the transport of trapped ions. The inter-change stability that is generated allows the study of the kinetic transport of trapped ions. This model has a threshold instability and can be simulated over a few tens confining time for either thermal bath constraint or flux constraint. For thermal baths constraint, the simulation shows a metastable state where zonal flows are prevailing while turbulence is non-existent. In the case of a flux-constraint, zonal flows appear and relax by exchanging energy with system's kinetic energy and turbulence energy. The competition between zonal flows and turbulence can be then simulated by a predator-prey model. 2 regimes can be featured out: an improved confining regime where zonal flows dominate transport and a turbulent regime where zonal flows and turbulent transport are of the same magnitude order. We show that flux as well as the Reynolds tensor play an important role in the dynamics of the zonal flows and that the gyrokinetic description is relevant for all plasma regions. (A.C.)

  14. Behavior of concrete cylinders confined by a ferro-geopolymer jacket in axial compression

    Directory of Open Access Journals (Sweden)

    Kothay Heng


    Full Text Available It is beneficial to utilize geopolymers for their potential properties to rehabilitate concrete structures. These properties include high adhesion to Ordinary Portland Cement (OPC concrete even at low degrees of interfacial roughness, high durability and good fire resistance. This paper introduces use of a ferro-geopolymer jacket to strengthen concrete columns. It is a kind of jacket constructed with a geopolymer mortar reinforced with a wire mesh. This study was conducted to investigate the behavior of concrete cylinders confined with a ferro-geopolymer jacket in axial compression. OPC concrete cylinders with 100 mm diameter and 200 mm height were fabricated. High calcium fly ash-based geopolymer mortar, activated with sodium hydroxide (NaOH and sodium silicate (Na2SiO3, cured at a temperature of 25 ºC was used. Ferro-geopolymer jackets with a25 mm thickness, were reinforced with 1, 2 and 3 layers of expanded metal mesh and cast around concrete cylinders. The study results revealed that the compressive load carrying capacity and axial stiffness of concrete cylinders were improved. A monolithic failure mode was obtained as a result of a strong adhesion between the geopolymer and the concrete core. Enhancement of compressive load carrying capacity of the jacketed concrete cylinders was caused by a combination of a confinement effect and the compressive load resistance of the jacket transferred from concrete core through bonding.

  15. How thermal stress alters the confinement of polymers vitrificated in nanopores (United States)

    Teng, Chao; Li, Linling; Wang, Yong; Wang, Rong; Chen, Wei; Wang, Xiaoliang; Xue, Gi


    Understanding and controlling the glass transition temperature (Tg) and dynamics of polymers in confined geometries are of significance in both academia and industry. Here, we investigate how the thermal stress induced by a mismatch in the coefficient of thermal expansion affects the Tg behavior of polystyrene (PS) nanorods located inside cylindrical alumina nanopores. The size effects and molecular weight dependence of the Tg are also studied. A multi-step relaxation process was employed to study the relationship between thermal stress and cooling rate. At fast cooling rates, the imparted thermal stress would overcome the yield stress of PS and peel chains off the pore walls, while at slow cooling rates, chains are kept in contact with the pore walls due to timely dissipation of the produced thermal stress during vitrification. In smaller nanopores, more PS chains closely contact with pore walls, then stronger internal thermal stress would be generated between core and shell of PS nanorod, which results in a larger deviation between two Tgs. The core part of PS shows lower Tg than bulk value, which can induce faster dynamics in the center region. A complex and important role stress plays is supposed in complex confinement condition, e.g., in nanopores, during vitrification.

  16. Sediment Core Laboratory (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  17. Adaptive core simulation (United States)

    Abdel-Khalik, Hany Samy

    The work presented in this thesis is a continuation of a master's thesis research project conducted by the author to gain insight into the applicability of inverse methods to developing adaptive simulation capabilities for core physics problems. Use of adaptive simulation is intended to improve the fidelity and robustness of important core attributes predictions such as core power distribution, thermal margins and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e. in-core instrumentations readings, to adapt the simulation in a meaningful way. A meaningful adaption will result in high fidelity and robust adapted core simulators models. To perform adaption, we propose an inverse theory approach in which the multitudes of input data to core simulators, i.e. reactor physics and thermal-hydraulic data, are to be adjusted to improve agreement with measured observables while keeping core simulators models unadapted. At a first glance, devising such adaption for typical core simulators models would render the approach impractical. This follows, since core simulators are based on very demanding computational models, i.e. based on complex physics models with millions of input data and output observables. This would spawn not only several prohibitive challenges but also numerous disparaging concerns. The challenges include the computational burdens of the sensitivity-type calculations required to construct Jacobian operators for the core simulators models. Also, the computational burdens of the uncertainty-type calculations required to estimate the uncertainty information of core simulators input data presents a demanding challenge. The concerns however are mainly related to the reliability of the adjusted input data. We demonstrate that the power of our proposed approach is mainly driven by taking advantage of this unfavorable situation. Our contribution begins with the realization that to obtain

  18. Juridical Regime of the Public Domain

    Directory of Open Access Journals (Sweden)

    Vasilica Negruţ


    Full Text Available The goods that form the administrative domain are classified in two categories: some to whichthe private law rules can be applied, some others meant for public use, unliable of individual approach,forming the public domain. The term of juridical regime of the public domain has in view the assembly ofrules that can be applied to the goods belonging to the public domain as well as the juridical relations bornbetween the owners of these goods and third persons. The public property goods are subjected exclusivelyto a juridical regime by public law, while the private property goods belonging to the public domain aregoverned simultaneously by two types of juridical regimes and more exactly by a mixed juridical regimeby common right and by power. The principles that can be applied to the public domain goods are: theinalienability, the imprescriptibility and the imperceptibility.

  19. Regimes of turbulence without an energy cascade

    CERN Document Server

    Barenghi, C F; Baggaley, A W


    Experiments and numerical simulations of turbulent $^4$He and $^3$He-B have established that, at hydrodynamic length scales larger than the average distance between quantum vortices, the energy spectrum obeys the same 5/3 Kolmogorov law which is observed in the homogeneous isotropic turbulence of ordinary fluids. The importance of the 5/3 law is that it points to the existence of a Richardson energy cascade from large eddies to small eddies. However, there is also evidence of quantum turbulent regimes without Kolmogorov scaling. This raises the important questions of why, in such regimes, the Kolmogorov spectrum fails to form, what is the physical nature of turbulence without energy cascade, and whether hydrodynamical models can account for the unusual behaviour of turbulent superfluid helium. In this work we describe simple physical mechanisms which prevent the formation of Kolmogorov scaling in the thermal counterflow, and analyze the conditions necessary for emergence of quasiclassical regime in quantum tu...

  20. Early detection of ecosystem regime shifts

    DEFF Research Database (Denmark)

    Lindegren, Martin; Dakos, Vasilis; Groeger, Joachim P.


    Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited....... Using real monitoring data of a key ecosystem component, we here apply multiple early-warning indicators in order to assess their ability to forewarn a major ecosystem regime shift in the Central Baltic Sea. We show that some indicators and methods can result in clear early-warning signals, while other...... methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face...

  1. The effect of system boundaries on the mean free path for confined gases

    Directory of Open Access Journals (Sweden)

    Sooraj K. Prabha


    Full Text Available The mean free path of rarefied gases is accurately determined using Molecular Dynamics simulations. The simulations are carried out on isothermal argon gas (Lennard-Jones fluid over a range of rarefaction levels under various confinements (unbounded gas, parallel reflective wall and explicit solid platinum wall bounded gas in a nanoscale domain. The system is also analyzed independently in constitutive sub-systems to calculate the corresponding local mean free paths. Our studies which predominate in the transition regime substantiate the boundary limiting effect on mean free paths owing to the sharp diminution in molecular free paths near the planar boundaries. These studies provide insight to the transport phenomena of rarefied gases through nanochannels which have established their potential in microscale and nanoscale heat transfer applications.

  2. Studies of plastic-ablator compressibility for direct-drive inertial confinement fusion on OMEGA. (United States)

    Hu, S X; Smalyuk, V A; Goncharov, V N; Knauer, J P; Radha, P B; Igumenshchev, I V; Marozas, J A; Stoeckl, C; Yaakobi, B; Shvarts, D; Sangster, T C; McKenty, P W; Meyerhofer, D D; Skupsky, S; McCrory, R L


    The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I approximately 0.5 to 1.5x10(15) W/cm2 using square (low-compression) and shaped (high-compression) pulses. Two-dimensional simulations with the radiative hydrocode DRACO show good agreement with measurements at laser intensities up to I approximately 10(15) W/cm2. These results provide the first experimental evidence for low-entropy, adiabatic compression of plastic shells in the laser intensity regime relevant to direct-drive inertial confinement fusion. A density reduction near the end of the drive at a high intensity of I approximately 1.5x10(15) W/cm2 has been correlated with the hard x-ray signal caused by hot electrons from two-plasmon-decay instability.

  3. Magnetic self organization, MHD active control and confinement in RFX-mod

    Energy Technology Data Exchange (ETDEWEB)

    Marrelli, L; Zanca, P; Valisa, M; Marchiori, G; Alfier, A; Bonomo, F; Gobbin, M; Piovesan, P; Terranova, D; Agostini, M; Alessi, C; Antoni, V; Apolloni, L; Auriemma, F; Barana, O; Bettini, P; Bolzonella, T; Bonfiglio, D; Brombin, M; Buffa, A; Canton, A; Cappello, S; Carraro, L; Cavazzana, R; Cavinato, M; Chitarin, G; Bello, S Dal; Lorenzi, A De; Escande, D F; Fassina, A; Franz, P; Gadani, G; Gaio, E; Gazza, E; Giudicotti, L; Gnesotto, F; Grando, L; Guo, S C; Innocente, P; Lorenzini, R; Luchetta, A; Malesani, G; Manduchi, G; Marcuzzi, D; Martin, P; Martini, S; Martines, E; Masiello, A; Milani, F; Moresco, M; Murari, A; Novello, L; Ortolani, S; Paccagnella, R; Pasqualotto, R; Peruzzo, S; Piovan, R; Pizzimenti, A; Pomaro, N; Predebon, I; Puiatti, M E; Rostagni, G; Sattin, F; Scarin, P; Serianni, G; Sonato, P; Spada, E; Soppelsa, A; Spizzo, G; Spolaore, M; Taccon, C; Taliercio, C; Toigo, V; Vianello, N; Zaccaria, P; Zaniol, B; Zanotto, L; Zilli, E; Zollino, G; Zuin, M [Consorzio RFX, Associazione EURATOM-ENEA sulla fusione, Corso Stati Uniti, 4, 35127-Padova (Italy)


    RFX-mod is a reversed field pinch (RFP) experiment equipped with a system that actively controls the magnetic boundary. In this paper we describe the results of a new control algorithm, the clean mode control (CMC), in which the aliasing of the sideband harmonics generated by the discrete saddle coils is corrected in real time. CMC operation leads to a smoother (i.e. more axisymmetric) boundary. Tearing modes rotate (up to 100 Hz) and partially unlock. Plasma-wall interaction diminishes due to a decrease of the non-axisymmetric shift of the plasma column. With the ameliorated boundary control, plasma current has been successfully increased to 1.5 MA, the highest for an RFP. In such regimes, the magnetic dynamics is dominated by the innermost resonant mode, the internal magnetic field gets close to a pure helix and confinement improves.

  4. Transitionless Enhanced Confinement and the Role of Radial Electric Field Shear

    Energy Technology Data Exchange (ETDEWEB)

    B. Coppi; D.R. Ernst; M.G. Bell; R.E. Bell; R.V. Budny; et al


    Evidence for the role of radial electric field shear in enhanced confinement regimes attained without sharp bifurcations or transitions is presented. Temperature scans at constant density, created in the reheat phase following deuterium pellet injection into supershot plasmas in the Tokamak Fusion Test Reactor [J.D. Strachan, et al., Phys. Rev. Lett. 58 (1987) 1004] are simulated using a first-principles transport model. The slow reheat of the ion temperature profile, during which the temperature nearly doubles, is not explained by relatively comprehensive models of transport due to Ion Temperature Gradient Driven Turbulence (ITGDT), which depends primarily on the (unchanging) electron density gradient. An extended model, including the suppression of toroidal ITGDT by self-consistent radial electric field shear, does reproduce the reheat phase.

  5. Regimes, Non-State Actors and the State System: A 'Structurational' Regime Model

    NARCIS (Netherlands)

    Arts, B.J.M.


    Regime analysis has become a popular approach in International Relations theory and in international policy studies. However, current regime models exhibit some shortcomings with regard to (1) addressing non-state actors, and in particular nongovernmental organizations (NGOs), (2) the balancing of

  6. Theoretical and experimental study of inverted annular film boiling and regime transition during reflood transients (United States)

    Mohanta, Lokanath

    The Loss of Coolant Accident (LOCA) is a design basis accident for light water reactors that usually determines the limits on core power. During a LOCA, film boiling is the dominant mode of heat transfer prior to the quenching of the fuel rods. The study of film boiling is important because this mode of heat transfer determines if the core can be safely cooled. One important film boiling regime is the so-called Inverted Annular Film Boiling (IAFB) regime which is characterized by a liquid core downstream of the quench front enveloped by a vapor film separating it from the fuel rod. Much research have been conducted for IAFB, but these studies have been limited to steady state experiments in single tubes. In the present work, subcooled and saturated IAFB are investigated using high temperature reflood data from the experiments carried out in the Rod Bundle Heat Transfer (RBHT) test facility. Parametric effects of system parameters including the pressure, inlet subcooling, and flooding rate on the heat transfer are investigated. The heat transfer behavior during transition to Inverted Slug Film Boiling (ISFB) regime is studied and is found to be different than that reported in previous studies. The effects of spacer grids on heat transfer in the IAFB and ISFB regimes are also presented. Currently design basis accidents are evaluated with codes in which heat transfer and wall drag must be calculated with local flow parameters. The existing models for heat transfer are applicable up to a void fraction of 0.6, i.e. in the IAFB regime and there is no heat transfer correlation for ISFB. A new semi-empirical heat transfer model is developed covering the IAFB and ISFB regimes which is valid for a void fraction up to 90% using the local flow variables. The mean absolute percentage error in predicting the RBHT data is 11% and root mean square error is 15%. This new semi-empirical model is found to compare well with the reflood data of FLECHT-SEASET experiments as well as data

  7. Core physics experiment of 100% MOX core: MISTRAL

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, T.; Matsu-ura, H.; Ueji, M. [Nuclear Power Engineering Corp., Tokyo (Japan); Cathalau, S.; Cabrillat, J.C.; Chauvin, J.P.; Finck, P.J.; Fougeras, P.; Flamenbaum, G.


    An extensive experimental program, MISTRAL, was undertaken in the EOLE critical facility of CEA in order to measure the main core physics parameters of 100% MOX loaded cores of light water reactors. The experimental program comprises four core configurations with high moderator to fuel ratio, including three homogeneous cores and one PWR type mock-up core. This paper presents the experiment of the first homogeneous core of uranium fuel as a reference core of the MOX cores and a part of the experiment of the second core, a 100% MOX homogeneous core. (author)

  8. Morphology-induced phonon spectra of CdSe/CdS nanoplatelets: core/shell vs. core-crown. (United States)

    Dzhagan, V; Milekhin, A G; Valakh, M Ya; Pedetti, S; Tessier, M; Dubertret, B; Zahn, D R T


    Recently developed two-dimensional colloidal semiconductor nanocrystals, or nanoplatelets (NPLs), extend the palette of solution-processable free-standing 2D nanomaterials of high performance. Growing CdSe and CdS parts subsequently in either side-by-side or stacked manner results in core-crown or core/shell structures, respectively. Both kinds of heterogeneous NPLs find efficient applications and represent interesting materials to study the electronic and lattice excitations and interaction between them under strong one-directional confinement. Here, we investigated by Raman and infrared spectroscopy the phonon spectra and electron-phonon coupling in CdSe/CdS core/shell and core-crown NPLs. A number of distinct spectral features of the two NPL morphologies are observed, which are further modified by tuning the laser excitation energy Eexc between in- and off-resonant conditions. The general difference is the larger number of phonon modes in core/shell NPLs and their spectral shifts with increasing shell thickness, as well as with Eexc. This behaviour is explained by strong mutual influence of the core and shell and formation of combined phonon modes. In the core-crown structure, the CdSe and CdS modes preserve more independent behaviour with only interface modes forming the phonon overtones with phonons of the core.

  9. DFT reactivity indices in confined many-electron atoms

    Indian Academy of Sciences (India)

    , global hardness and softness are reported for a representative set of spherically confined atoms of IA, IIA, VA and VIIIA series in the periodic table. The atomic electrons are confined within the impenetrable spherical cavity defined by a given ...

  10. Shearing Nanometer-Thick Confined Hydrocarbon Films: Friction and Adhesion

    DEFF Research Database (Denmark)

    Sivebæk, I. M.; Persson, B. N. J.


    We present molecular dynamics (MD) friction and adhesion calculations for nanometer-thick confined hydrocarbon films with molecular lengths 20, 100 and 1400 carbon atoms. We study the dependency of the frictional shear stress on the confining pressure and sliding speed. We present results...

  11. Investigation of stress–strain models for confined high strength ...

    Indian Academy of Sciences (India)

    The ascending branch of stress–strain curves depended on the ratio of confinement reinforcement was similar to the modified Kent–Park model and the descending branch similar to the Nagashima model. Keywords. High strength concrete; confined concrete; stress–strain models; ductility toughness. 1. Introduction.

  12. Confinement, average forces, and the Ehrenfest theorem for a one ...

    Indian Academy of Sciences (India)

    The topics of confinement, average forces, and the Ehrenfest theorem are examined for a particle in one spatial dimension. Two specific cases are considered: A free particle moving on the entire real line, which is then permanently confined to a line segment or `a box' (this situation is achieved by taking the limit V 0 → ∞ in ...

  13. The oil tax regime of Azerbaijan

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Gerard


    Azerbaijan has a long history in the oil business and a chance of a spectacular future. To understand why the oil tax regime evolved into its present form and how it is likely to develop, it is necessary to know something of the country's history and the commercial environment. Consequently the presentation begins by discussing these items. It then outlines the Production Sharing Agreement regime in Azerbaijan and then deals with the Kazakh and Georgian Tax Codes, as these are likely to be the basis of a new general tax law in Azerbaijan from 1999. The presentation includes comments on the New Draft Tax Code of 1998.

  14. Regimes of flow past a vortex generator

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, V.L.; Naumov, I.V.


    particle image velocimetry (SPIV). Based on the obtained SPIV data, a map of the regimes of flow past the vortex generator has been constructed. One region with a developed stable multivortex system on this map reaches the vicinity of the optimum angle of attack of the vortex generator.......A complete parametric investigation of the development of multi-vortex regimes in a wake past simple vortex generator has been carried out. It is established that the vortex structure in the wake is much more complicated than a simple monopole tip vortex. The vortices were studied by stereoscopic...

  15. Atmospheric weather regimes over tropical South America (United States)

    Connors, Vickie S.; Garstang, Michael; Nolf, Scott R.


    Infrared radiance measurements by the GOES-6 satellite during April 1986 through April 1987 were used to characterize and identify distinct regimes of persistent large-scale cloudiness patterns over the Amazon Basin. It is suggested that the energetics of the tropical troposphere over the Amazon Basin can be directly related to the GOES large-scale cloudiness patterns. The geometry and persistence of the cloud patterns are influenced by shifts in general circulation features and are likely modulated by 4- to 5-day and 40- to 60-day waves. Diurnal forcing effects are more pronounced during weather regimes characterized by prominently clear skies over land areas.

  16. Towards a Global Regime of Higher Education

    Directory of Open Access Journals (Sweden)

    Paolo Do


    Full Text Available This paper rethinks the spatialization of educational institutions at the global level, scaling and rescaling the space of the university as an inclusive process that makes academic knowledge production something heterogeneous, complex and composite, and proposing a regime for the higher education system based on a stratified relationship that is asymmetrical and geographically displaced. Moreover it outlines the “new” political economy of knowledge, which is a particular mechanism in contemporary capitalist production, capable of creating an artificial scarcity of knowledge by means of hierarchies, and reproducing the classical law of value in a regime based on abundance instead of scarcity.

  17. Can Psychiatric Rehabilitation Be Core to CORE? (United States)

    Olney, Marjorie F.; Gill, Kenneth J.


    Purpose: In this article, we seek to determine whether psychiatric rehabilitation principles and practices have been more fully incorporated into the Council on Rehabilitation Education (CORE) standards, the extent to which they are covered in four rehabilitation counseling "foundations" textbooks, and how they are reflected in the…

  18. Dynamical properties of nimodipine molecules confined in SBA-15 matrix (United States)

    Kiwilsza, A.; Pajzderska, A.; Mielcarek, J.; Jenczyk, J.; Wąsicki, J.


    The paper reports results of 13C and 1H ssNMR for nimodipine confined in mesopores of SBA-15 for the samples (i) containing nimodipine molecules inside and on the external surface of silica, (ii) containing nimodipine only inside pores forming an incomplete monolayer on the surface (iii) for bulk nimodipine. The measurements permitted comparison of the dynamics of nimodipine bulk and confined in pores. The confined nimodipine is in an amorphous state and has additional degrees of rotational freedom with respect to the bulk one. The height of the energy barrier related to the rotation of methyl groups in confined nimodipine is lower than in bulk nimodipine. The higher mobility of nimodipine molecules confined in silica pores can explain the higher release rate of nimodipine from silica matrix than dissolution rate of bulk drug.

  19. Confined space entry program for the Westinghouse Hanford Company

    Energy Technology Data Exchange (ETDEWEB)

    Cornell, T.M.


    To comply with anticipated OSHA regulatory requirements concerning Permit-Required Confined Spaces, Westinghouse Hanford Company (WHC) created a Confined Spaces Task Team. The primary focus of the task team was to prepare a formal Confined Space Entry (CSE) Program that would ensure full compliance with the anticipated OSHA requirements. A comprehensive training plan was also prepared and submitted for approval as soon as the new CSE Program was approved and released for implementation. On January 14, 1993, OSHA released their final ruling which contained several further changes, requiring the WHC Confined Space Entry Program and Training Plan to be revised. The revised training manual and lessons learned in establishing a Confined Space Entry Program are presented.

  20. Statistics of exchange rate regimes in Nigeria | Ajaraogu | Global ...

    African Journals Online (AJOL)

    The three distinct exchange rate regimes of Nigeria were subjected to Autoregressive Integrated Moving Average (ARIMA) modeling in order to compare them with respect to model structure. It was found that the three regimes admit different models. Regime one admits Moving average model of order 2, Regime two admits ...

  1. Statistics of exchange rate regimes in Nigeria | Iwueze | Global ...

    African Journals Online (AJOL)

    The three distinct exchange rate regimes of Nigeria were subjected to Autoregressive Integrated Moving Average (ARIMA) modeling in order to compare them with respect to model structure. It was found that the three regimes admit different models. Regime one admits Moving average model of order 2, Regime two admits ...

  2. Confined zone dispersion flue gas desulfurization demonstration

    Energy Technology Data Exchange (ETDEWEB)


    The confined zone dispersion (CZD) process involves flue gas post-treatment, physically located between a boiler's outlet and its particulate collector, which in the majority of cases is an electrostatic precipitator. The features that distinguish this process from other similar injection processes are: Injection of an alkaline slurry directly into the duct, instead of injection of dry solids into the duct ahead of a fabric filter. Use of an ultrafine calcium/magnesium hydroxide, type S pressure-hydrated dolomitic lime. This commercial product is made from plentiful, naturally occurring dolomite. Low residence time, made possible by the high effective surface area of the Type S lime. Localized dispersion of the reagent. Slurry droplets contact only part of the gas while the droplets are drying, to remove up to 50 percent of the S0{sub 2} and significant amounts of NO{sub x}. The process uses dual fluid rather than rotary atomizers. Improved electrostatic precipitator performance via gas conditioning from the increased water vapor content, and lower temperatures. Supplemental conditioning with S0{sub 3} is not believed necessary for satisfactory removal of particulate matter.

  3. Diagnostics for magnetic confinement fusion research (United States)

    Weller, Arthur


    Significant progress towards the development of an attractive fusion energy source based on magnetic or inertial plasma confinement has been achieved within the international fusion energy program. High-level diagnostics capabilities are required to characterize fusion plasmas and to achieve a sound physics basis to design a fusion power plant. A large variety of different measuring techniques is used, most of them based on the detection of electromagnetic radiation in a wide range of wavelengths or of particles emitted from the plasma. Active probing by laser and particle beams permits to measure local plasma parameters directly, whereas passive measurements and imaging methods require unfolding and tomographic reconstruction techniques in order to obtain the spatial source distribution. Most diagnostics systems are limited in the accessible parameter range, in accuracy, temporal and spatial resolution, energy resolution and hardiness in a harsh environment, so that redundancy and complementarity of different methods is desirable. A considerable synergy exists between plasma diagnostics for fusion and astrophysics research. In particular, novel imaging detectors developed for the observation of astrophysical objects may be applied to fusion devices, too. An overview of diagnostics requirements, measuring techniques and selected results are presented with an emphasis of imaging diagnostics in toroidal magnetic fusion devices.

  4. Human Adaptation to Isolated and Confined Environments (United States)

    Evans, Gary W.; Stokols, Daniel; Carrere, Sybil


    A study was conducted over seven months in a winter Antarctic isolated and confined environment (ICE). Physiological and psychological data was collected several times a week. Information was collected on a monthly basis on behavior and the use of physical facilities. Adaptation and information indicated that there was a significant decrease in epinephrine and norepinephrine during the middle trimester of the winter. No vital changes were found for blood pressure. Self reports of hostility and anxiety show a linear increase. There were no significant changes in depression during ICE. The physiological and psychological data do not move in a synchronous fashion over time. The data also suggest that both ambient qualities of an ICE and discrete social environmental events, such as the arrival of the summer crew, have an impact on the outcome measures used. It may be most appropiate to develop a model for ICE's that incorporates not only global chronic stressors common to all ICE's but also the role of discrete environmental effects which can minimize or enhance the influence of more chronic stressors. Behavioral adjustment information highlight the importance of developing schedules which balance work and recreational activities.

  5. Optical properties of matrix confined species (United States)

    Lezhnina, M. M.; Kynast, U. H.


    A majority of optically functional materials can be perceived as a liaison between ionic or molecular guests and a more or less rigid host. The guests exhibit an optical function, whereas the host provides suitable space, both of them synergistically complementing each other. The embracement of guests and hosts is often very intimate, as e.g. in typical phosphors, where luminescent ions even become part of the host. While the host-guest terminology usually is not applied to such marriages, the term becomes appropriate, if the host grants some degrees of spatial freedom, yet giving order and structure to its guests. Zeolites, clays and inverse opals are porous materials naturally providing hospitable cavities, channels or other compartments, and at the same time the guests are often demanded to occupy preassigned positions within these, or to structurally adapt to the interior host topology. Whereas zeolites and clays are merely patient providers of guest space, inverse opals, can actively turn the light on and off. The present article summarises and highlights recent experimental evidence, ongoing research and some envisaged merits resulting from the interaction of matrix confined luminescent ions, complexes and molecules with a focus on the optical properties of rare earth based materials.

  6. Fuzzy Dark Matter from Infrared Confining Dynamics (United States)

    Davoudiasl, Hooman; Murphy, Christopher W.


    A very light boson of mass O (10-22) eV may potentially be a viable dark matter (DM) candidate, which can avoid phenomenological problems associated with cold DM. Such "fuzzy DM (FDM)" may naturally be an axion with a decay constant fa˜1 016- 1 018 GeV and a mass ma˜μ2/fa with μ ˜1 02 eV . Here, we propose a concrete model, where μ arises as a dynamical scale from infrared confining dynamics, analogous to QCD. Our model is an alternative to the usual approach of generating μ through string theoretic instanton effects. We outline the features of this scenario that result from various cosmological constraints. We find that those constraints are suggestive of a period of mild of inflation, perhaps from a strong first order phase transition, that reheats the standard model (SM) sector only. A typical prediction of our scenario, broadly speaking, is a larger effective number of neutrinos compared to the SM value Neff≈3 , as inferred from precision measurements of the cosmic microwave background. Some of the new degrees of freedom may be identified as "sterile neutrinos," which may be required to explain certain neutrino oscillation anomalies. Hence, aspects of our scenario could be testable in terrestrial experiments, which is a novelty of our FDM model.

  7. Electrostatically confined trilayer graphene quantum dots (United States)

    Mirzakhani, M.; Zarenia, M.; Vasilopoulos, P.; Peeters, F. M.


    Electrically gating of trilayer graphene (TLG) opens a band gap offering the possibility to electrically engineer TLG quantum dots. We study the energy levels of such quantum dots and investigate their dependence on a perpendicular magnetic field B and different types of stacking of the graphene layers. The dots are modeled as circular and confined by a truncated parabolic potential which can be realized by nanostructured gates or position-dependent doping. The energy spectra exhibit the intervalley symmetry EKe(m ) =-EK'h(m ) for the electron (e ) and hole (h ) states, where m is the angular momentum quantum number and K and K ' label the two valleys. The electron and hole spectra for B =0 are twofold degenerate due to the intervalley symmetry EK(m ) =EK'[-(m +1 ) ] . For both ABC [α =1.5 (1.2) for large (small) R ] and ABA (α =1 ) stackings, the lowest-energy levels show approximately a R-α dependence on the dot radius R in contrast with the 1 /R3 one for ABC-stacked dots with infinite-mass boundary. As functions of the field B , the oscillator strengths for dipole-allowed transitions differ drastically for the two types of stackings.

  8. Luttinger hydrodynamics of confined one-dimensional Bose gases with dipolar interactions

    Energy Technology Data Exchange (ETDEWEB)

    Citro, R [Dipartimento di Fisica ' E R Caianiello' and CNISM, Universita degli Studi di Salerno, Salerno (Italy); Palo, S De [DEMOCRITOS INFM-CNR and Dipartimento di Fisica Teorica, Universita Trieste, Trieste (Italy); Orignac, E [Laboratoire de Physique de l' Ecole Normale Superieure de Lyon, CNRS-UMR5672, Lyon (France); Pedri, P [Laboratoire de Physique Theorique et Modeles Statistiques, Universite Paris-Sud, CNRS-UMR8626, Orsay (France); Chiofalo, M-L [INFN, Department of Mathematics and Faculty of Pharmacy, University of Pisa, Pisa (Italy)], E-mail:


    Ultracold bosonic and fermionic quantum gases confined to quasi-one-dimensional (1D) geometry are promising candidates for probing fundamental concepts of Luttinger liquid (LL) physics. They can also be exploited for devising applications in quantum information processing and precision measurements. Here, we focus on 1D dipolar Bose gases, where evidence of super-strong coupling behavior has been demonstrated by analyzing the low-energy static and dynamical structures of the fluid at zero temperature by a combined reptation quantum Monte Carlo (RQMC) and bosonization approach. Fingerprints of LL behavior emerge in the whole crossover from the already strongly interacting Tonks-Girardeau at low density to a dipolar density wave regime at high density. We have also shown that a LL framework can be effectively set up and utilized to describe this strongly correlated crossover physics in the case of confined 1D geometries after using the results for the homogeneous system in LL hydrodynamic equations within a local density approximation. This leads to the prediction of observable quantities such as the frequencies of the collective modes of the trapped dipolar gas under the more realistic conditions that could be found in ongoing experiments. The present paper provides a description of the theoretical framework in which the above results have been worked out, making available all the detailed derivations of the hydrodynamic Luttinger equations for the inhomogeneous trapped gas and of the correlation functions for the homogeneous system.

  9. Strongly Confined Spoof Surface Plasmon Polaritons Waveguiding Enabled by Planar Staggered Plasmonic Waveguides (United States)

    Ye, Longfang; Xiao, Yifan; Liu, Yanhui; Zhang, Liang; Cai, Guoxiong; Liu, Qing Huo


    We demonstrate a novel route to achieving highly efficient and strongly confined spoof surface plasmon polaritons (SPPs) waveguides at subwavelength scale enabled by planar staggered plasmonic waveguides (PSPWs). The structure of these new waveguides consists of an ultrathin metallic strip with periodic subwavelength staggered double groove arrays supported by a flexible dielectric substrate, leading to unique staggered EM coupling and waveguiding phenomenon. The spoof SPP propagation properties, including dispersion relations and near field distributions, are numerically investigated. Furthermore, broadband coplanar waveguide (CPW) to planar staggered plasmonic waveguide (PSPW) transitions are designed to achieve smooth momentum matching and highly efficient spoof SPP mode conversion. By applying these transitions, a CPW-PSPW-CPW structure is designed, fabricated and measured to verify the PSPW’s propagation performance at microwave frequencies. The investigation results show the proposed PSPWs have excellent performance of deep subwavelength spoof SPPs confinement, long propagation length and low bend loss, as well as great design flexibility to engineer the propagation properties by adjusting their geometry dimensions and material parameters. Our work opens up a new avenue for development of various advanced planar integrated plasmonic devices and circuits in microwave and terahertz regimes.

  10. Confinement-induced reduction in phase segregation and interchain disorder in bulk heterojunction films. (United States)

    Ashraf, Ahsan; Dissanayake, D M Nanditha M; Germack, David S; Weiland, Conan; Eisaman, Matthew D


    The effects of thin-film confinement on the material properties of ultrathin polymer (electron donor):fullerene (electron acceptor) bulk heterojunction films can be important for both fundamental understanding and device applications such as thin-film photovoltaics. We use variable angle spectroscopic ellipsometry and near edge X-ray absorption fine structure spectroscopy to measure the optical constants, donor-acceptor volume fraction profile, and the degree of interchain order as a function of the thickness of a poly(3-hexythiophene-2,5-diyl) and phenyl-C61-butyric acid methyl ester bulk heterojunction film. We find that as the thickness of the bulk heterojunction film is decreased from 200 nm to the thickness confinement regime (less than 20 nm), the vertical phase segregation gradient of the donor and acceptor phases becomes less pronounced. In addition, observing the change in exciton bandwidth and the shift of absorption resonances (0-0 and 0-1) relative to neat donor and acceptor films, we find that the conjugation length and disorder in ultrathin films (20 nm) are less affected than thicker (200 nm) films by the addition of fullerene into the polymer. We believe that these findings could be important for discovering methods of precisely controlling the properties of bulk heterojunction films with crucial implications for designing more efficient organic-based photovoltaics.

  11. Impact of lateral carrier confinement on electro-optical tuning properties of polariton condensates

    Energy Technology Data Exchange (ETDEWEB)

    Brodbeck, S.; Suchomel, H.; Amthor, M.; Wolf, A.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Schneider, C. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Mediterranean Institute of Fundamental Physics, Via Appia Nuova 31, 00040 Rome (Italy); Höfling, S. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY 16 9SS (United Kingdom)


    Electro-optical measurements on exciton-polaritons below and above the condensation threshold are performed on high quality, pin-doped microcavities with embedded GaAs quantum wells. Applying an external electric field shifts the polariton emission by hundreds of μeV both in the linear and the nonlinear regime. We study three device geometries to investigate the influence of carrier confinement in the plane of the quantum well on the electro-optical tuning properties. In the conventional micropillar geometry, the electric field tuning behavior is dominated by the effects of carrier tunneling and electric field screening that manifest in a blueshift of the polariton emission. In stark contrast, for a planar sample geometry, we can significantly extend the range of electric fields and a redshift is observed. To separate the contributions of quantum confined Stark effect and reduced exciton oscillator strength to the energy shift, we study a third sample where the etching of micropillars is stopped just above the active region. In this semi-planar geometry, exciton and polariton emissions can be measured simultaneously. As for the planar geometry, redshifts of the polariton emission are observed below and above threshold that are well reproduced by theoretical shifts.

  12. Lunar Core and Tides (United States)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.


    Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2,3,4] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening, which in the past has been marginal but improving [3,4,5], now seems significant. Direct detection of the core moment has not yet been achieved.

  13. Nonlinear optics at the single-photon level inside a hollow core fiber

    DEFF Research Database (Denmark)

    Hofferberth, Sebastian; Peyronel, Thibault; Liang, Qiyu


    Cold atoms inside a hollow core fiber provide an unique system for studying optical nonlinearities at the few-photon level. Confinement of both atoms and photons inside the fiber core to a diameter of just a few wavelengths results in high electric field intensity per photon and large optical...... depths with a relatively small number of atoms. We present our experimental apparatus and discuss results regarding all-optical switching at ultra-low light levels....

  14. Supplemental heating of conventional Inertial Confinement Fusion (United States)

    Thomas, B. R.; Hughes, S. J.; Garbett, W. J.; Sircombe, N. J.


    We report a new ICF scheme whereby a capsule is imploded to near ignition conditions and subsequently flooded with hot electrons generated from a short-pulse laser- plasma interaction so as to heat the whole assembly by a few hundred eV. The cold dense shell pressure is increased by a larger factor than that of the hot spot at the capsule core, so that further heating and compression of the hot spot occurs. We suggest it may be possible to drive the capsule to ignition by the pressure augmentation supplied by this extra deposition of energy.


    Directory of Open Access Journals (Sweden)

    José Teixeira de Seixas Filho


    Full Text Available We used 525 bullfrog tadpoles, distributed into 15 boxes with one tadpole per liter. The water was daily renewal (200%. The feeding regimes were constituted of five arrangements using seven commercial rations with levels of 22, 28, 32, 36, 40, 45 and 55% of crude protein (CP, supplied every 15 days. We used a random blocks design, subdivided plots with three replications. The subplots were constituted of five biometries: at the beginning of the experiment, at 15, 30, 45, and 60 days. The tadpoles submitted to feeding regime FR1, with 22, 32, 36, and 40% of CP, presented the highest consumption and the same performance as the others. Tadpoles that received FR5, with 40, 45, 45 and 50% of CP, presented greater weight, however, they showed smaller weight gain, greater consumption, conversion and mortality, indicating that this regime is expensive and not adequate for management. Feeding regimes FR2, with 28, 32, 36 and 40% of CP, and FR3, with 32, 36, 40 and 45% of CP, were more adjusted to this kind of management. Animals in all treatments showed higher performance that animals fed traditionally.

  16. A Comparative Typology of Pension Regimes

    NARCIS (Netherlands)

    Arjan Soede; Cok Vrooman


    This report presents an empirical typology of pension regimes in the European Union, the US, Canada, Australia and Norway. The categorisation is based on 34 quantitative and qualitative characteristics of the mandatory parts of the pension systems in these countries. The empirical analysis shows

  17. Mesoscopic effects in the quantum Hall regime

    Indian Academy of Sciences (India)

    may be of relevance to experimentally observed transitions between quantum Hall states and the insulating phase ... In this paper, we discuss the mesoscopic effects in the quantum Hall regime, in particu- lar the effects of ...... finite sizes, due to the presence of long length scales, quantum interference effects can be cut-off at ...

  18. Economic Performance and North Korean Regime Legitimacy (United States)


    Expansion and Counter Reforms .......................................56  2.  A Dark Horse of Hope... fertilizers and pesticides. The regime succeeded in increasing yields, but production was “highly vulnerable to availability of these critical...economic gains to maintain its position on top. 2. A Dark Horse of Hope? With the sudden passing of Kim Jong-il in 2011 a widely unknown, fresh

  19. Ignitability of materials in transitional heating regimes (United States)

    Mark A. Dietenberger


    Piloted ignition behavior of materials, particularly wood products, during transitions between heating regimes is measured and modeled in a cone calorimetry (ISO 5660) heating environment. These include (1) effect of material thickness, density, moisture content, and paint coating variations on thermal response characteristics, (2) effect of fire retardant treatment...

  20. Decentralization and Diversification in Forest Management Regimes ...

    African Journals Online (AJOL)

    This often creates conflicts with local communities, who are excluded from timber use and only can collect non-timber forest products. The regime characteristics as found in the Uluguru Nature Reserve and the Ihanga district generally reflect the common characteristics of joint forest management schemes and district forest ...

  1. Quality Regimes in Agro-Food Industries

    DEFF Research Database (Denmark)

    Staricco, Juan Ignacio; Ponte, Stefano


    In this article, we examine the transformative potential of changing quality regimes in agro-food industries through the analysis of whether Fair Trade wine in Argentina provides a meaningful economic alternative that goes beyond the impact it has on direct beneficiaries. The wine sector has a lo...... producing table wine for the domestic market, Fair Trade is actually further marginalizing them....

  2. Chapter 3: Plant invasions and fire regimes (United States)

    Matthew L. Brooks


    The alteration of fire regimes is one of the most significant ways that plant invasions can affect ecosystems (Brooks and others 2004; D'Antonio 2000; D'Antonio and Vitousek 1992; Vitousek 1990). The suites of changes that can accompany an invasion include both direct effects of invaders on native plants through competitive interference, and indirect effects...

  3. Radiative Effects of Global MODIS Cloud Regimes (United States)

    Oraiopoulos, Lazaros; Cho, Nayeong; Lee, Dong Min; Kato, Seiji


    We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.

  4. Knowledge Regimes and Contradictions in Education Reforms (United States)

    Aasen, Petter; Prøitz, Tine Sophie; Sandberg, Nina


    The article outlines a theoretical framework for understanding education policy and education reforms based on the concept of knowledge regimes. The concept refers to understandings and definitions of governance and procedural aspects, manners of governing and curriculum issues, thus it comprises contents, structures, and processes of education…

  5. Water governance regimes: Dimensions and dynamics

    NARCIS (Netherlands)

    Bressers, Johannes T.A.; Kuks, Stefanus M.M.


    The concept of water governance is distinctive through its focus on not only public in- tervention, but also on self-organisation as a way to deal with water issues. This article first elaborates a framework with five dimensions to describe governance regimes. Thereafter it illustrates and uses this

  6. Searching for an Appropriate Exchange Rate Regime

    Directory of Open Access Journals (Sweden)

    Yunjong Wang


    Full Text Available This paper attempts to survey current debates on the choice of exchange rate regime in emerging market economies. The issue of choosing an appropriate exchange rate regime is being actively discussed since the recent Asian crisis. As a lesson from the recent crises, one widely shared conclusion is that soft peg exchange rate regimes are extremely vulnerable in a world of volatile capital movements. Consequently, new orthodoxy based on the impossible trinity hypothesis favours two corner solutions ― greater flexibility or credible institutional assurance, like a currency board system or dollarization. Nevertheless, questions whether such corner solutions are adequate for developing countries are rising of late. "Fear of floating" is still conspicuous in many developing countries having adopted nominally a free-floating exchange rate regime. Developing countries are sensitive to exchange rate fluctuations because the cost of exchange rate volatility is greater than the benefit when compared to developed countries. Monitoring bands is a compromise solution, but it still needs further enhancement of estimation techniques for fundamental equilibrium exchange rates in order to make those estimation results more workable in practice. Other alternatives include the creation of soft peg of the G-3 currencies. Despite counterarguments, the stability of G-3 currencies could prove to be beneficial to emerging market economies.

  7. The Forex Regime and EMU Expansion

    NARCIS (Netherlands)

    P.W. van Foreest; C.G. de Vries (Casper)


    textabstractThis paper provides empirical evidence that, irrespective of the foreign exchange rate regime, countries with high monetary volatility have lower relative output growth rates. It is argued that due to the forward looking nature of the foreign exchange market, exchange rate stability

  8. Optimal dividend distribution under Markov regime switching

    NARCIS (Netherlands)

    Jiang, Z.; Pistorius, M.


    We investigate the problem of optimal dividend distribution for a company in the presence of regime shifts. We consider a company whose cumulative net revenues evolve as a Brownian motion with positive drift that is modulated by a finite state Markov chain, and model the discount rate as a

  9. US Support for Democracy in Authoritarian Regimes (United States)


    regime change on Zimbabwe. This fallacious idea is being codified in the published military doctrinal manuals of the ZDF. The new doctrines are a clear...the ailing Zimbabwean economy. Major foreign companies such as Nestle and Anglo American have been forced to scale back or cancel operations due to

  10. Cross-scale analysis of fire regimes (United States)

    Donald A. Falk; Carol Miller; Donald McKenzie; Anne E. Black


    Cross-scale spatial and temporal perspectives are important for studying contagious landscape disturbances such as fire, which are controlled by myriad processes operating at different scales. We examine fire regimes in forests of western North America, focusing on how observed patterns of fire frequency change across spatial scales. To quantify changes in fire...

  11. The t-core of an s-core


    Fayers, Matthew


    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  12. Unifying description of the damping regimes of a stochastic particle in a periodic potential

    Directory of Open Access Journals (Sweden)

    Antonio Piscitelli, Massimo Pica Ciamarra


    Full Text Available We analyze the classical problem of the stochastic dynamics of a particle confined in a periodic potential, through the so called Il'in and Khasminskii model, with a novel semi-analytical approach. Our approach gives access to the transient and the asymptotic dynamics in all damping regimes, which are difficult to investigate in the usual Brownian model. We show that the crossover from the overdamped to the underdamped regime is associated with the loss of a typical time scale and of a typical length scale, as signaled by the divergence of the probability distribution of a certain dynamical event. In the underdamped regime, normal diffusion coexists with a non Gaussian displacement probability distribution for a long transient, as recently observed in a variety of different systems. We rationalize the microscopic physical processes leading to the non-Gaussian behavior, as well as the timescale to recover the Gaussian statistics. The theoretical results are supported by numerical calculations and are compared to those obtained for the Brownian model.

  13. Self-healing of sandwich structures with a grid stiffened shape memory polymer syntactic foam core (United States)

    John, Manu; Li, Guoqiang


    In this paper, a new sandwich with an orthogrid stiffened shape memory polymer (SMP) based syntactic foam core was proposed, fabricated, programmed, impacted, healed (sealed), and compression tested, for the purposes of healing impact damage repeatedly and almost autonomously. Two prestrain levels (3% and 20%), two impact energy levels (30.0 and 53.3 J), and two recovery (healing) conditions (2D confined and 3D confined) were employed in this paper. Up to seven impact-healing cycles were conducted. Macroscopic and microscopic damage-healing observation and analysis were implemented. Residual strength was evaluated using an anti-buckling compression test fixture. It was found that the healing efficiency was over 100% for almost all the impact-healing cycles; programming using 20% prestrain led to higher residual strength than that with 3% prestrain; 3D confined recovery resulted in higher residual strength than 2D confined recovery; and as the impact energy increased, the healing efficiency slightly decreased.

  14. Dependence of Core and Extended Flux on Core Dominance ...

    Indian Academy of Sciences (India)


    Jan 27, 2016 ... Based on two extragalactic radio source samples, the core dominance parameter is calculated, and the correlations between the core/extended flux density and core dominance parameter are investigated. When the core dominance parameter is lower than unity, it is linearly correlated with the core flux ...

  15. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.


    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  16. Dependence of Core and Extended Flux on Core Dominance ...

    Indian Academy of Sciences (India)

    Abstract. Based on two extragalactic radio source samples, the core dominance parameter is calculated, and the correlations between the core/extended flux density and core dominance parameter are investi- gated. When the core dominance parameter is lower than unity, it is linearly correlated with the core flux density, ...

  17. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core


    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise


    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  18. Regime shifts in the anthropocene: drivers, risks, and resilience. (United States)

    Rocha, Juan Carlos; Peterson, Garry D; Biggs, Reinette


    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers.

  19. Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

    Directory of Open Access Journals (Sweden)

    Noor A. Nama


    Full Text Available Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001-(1×1 surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

  20. The concept of regime values: Are revitalization and regime change possible?


    Overeem, P.


    Among the plethora of public values, one special class is that of “regime values.” This notion plays a central role in the constitutional approach to public administration mainly developed by the late John A. Rohr. In this article, an attempt is made to assess the viability of Rohr’s concept of regime values and its applicability outside the United States. After brief overviews of the constitutional approach in general and Rohr’s use of the concept of regime values in particular, it is argued...