WorldWideScience

Sample records for tail electrons

  1. Collisional relaxation of electron tail distribution

    International Nuclear Information System (INIS)

    Yamagiwa, Mitsuru; Okamoto, Masao.

    1985-05-01

    Relaxation due to the Coulomb collisions of the electron velocity distribution function with a high energy tail is investigated in detail. In the course of the relaxation, a 'saddle' point can be created in velocity space owing to upsilon -3 dependence of the deflection rate and a positive slope or a 'dip' appears in the tail direction. The time evolution of the electron tail is studied analytically. A comparison is made with numerical results by using a Fokker-Planck code. Also discussed is the kinetic instability concerned with the positive slope during the relaxation. (author)

  2. Turbulence-driven anisotropic electron tail generation during magnetic reconnection

    Science.gov (United States)

    DuBois, A. M.; Scherer, A.; Almagri, A. F.; Anderson, J. K.; Pandya, M. D.; Sarff, J. S.

    2018-05-01

    Magnetic reconnection (MR) plays an important role in particle transport, energization, and acceleration in space, astrophysical, and laboratory plasmas. In the Madison Symmetric Torus reversed field pinch, discrete MR events release large amounts of energy from the equilibrium magnetic field, a fraction of which is transferred to electrons and ions. Previous experiments revealed an anisotropic electron tail that favors the perpendicular direction and is symmetric in the parallel. New profile measurements of x-ray emission show that the tail distribution is localized near the magnetic axis, consistent modeling of the bremsstrahlung emission. The tail appears first near the magnetic axis and then spreads radially, and the dynamics in the anisotropy and diffusion are discussed. The data presented imply that the electron tail formation likely results from a turbulent wave-particle interaction and provides evidence that high energy electrons are escaping the core-localized region through pitch angle scattering into the parallel direction, followed by stochastic parallel transport to the plasma edge. New measurements also show a strong correlation between high energy x-ray measurements and tearing mode dynamics, suggesting that the coupling between core and edge tearing modes is essential for energetic electron tail formation.

  3. Electron energization in the geomagnetic tail current sheet

    International Nuclear Information System (INIS)

    Lyons, L.R.

    1984-01-01

    Electron motion in the distant tail current sheet is evaluated and found to violate the guiding center approximation at energies > or approx. =100 eV. Most electrons within the energy range approx.10 -1 -10 2 keV that enter the current sheet become trapped within the magnetic field reversal region. These electrons then convect earthward and gain energy from the cross-tail electric field. If the energy spectrum of electrons entering the current sheet is similar to that of electrons from the boundary layer surrounding the magnetotail, the energy gain from the electric field produces electron energy spectra comparable to those observed in the earth's plasma sheet. Thus current sheet interactions can be a significant source of particles and energy for plasma sheet electrons as well as for plasma sheet ions. A small fraction of electrons within the current sheet has its pitch angles scattered so as to be ejected from the current sheet within the atmospheric loss cone. These electrons can account for the electron precipitation near the high-latitude boundary of energetic electrons, which is approximately isotropic in pitch angle up to at least several hundred keV. Current sheet interaction should cause approximately isotropic auroral precipitation up to several hundred keV energies, which extends to significantly lower latitudes for ions than for electrons in agreement with low-altitude satellite observations. Electron precipitation associated with diffuse aurora generally has a transition at 1-10 keV to anisotropic pitch angle distributions. Such electron precipitation cannot be explained by current sheet interactions, but it can be explained by pitch angle diffusion driven by plasma turbulence

  4. Detection of bump-on-tail reduced electron velocity distributions at the electron foreshock boundary

    International Nuclear Information System (INIS)

    Fitzenreiter, R.J.; Klimas, A.J.; Scudder, J.D.

    1984-02-01

    Reduced velocity distributions are derived from three-dimensional measurements of the velocity distribution of electrons in the 7 to 500 eV range in the electron foreshock. Bump-on-tail reduced distributions are presented for the first time at the foreshock boundary consistent with Filbert and Kellogg's proposed time-of-flight mechanism for generating the electron beams. In a significant number of boundary crossings, bump-on-tail reduced distributions were found in consecutive 3 sec measurements made 9 sec apart. It is concluded that, although the beams are linearly unstable to plasma waves according to the Penrose criterion, they persist on a time scale of 3 to 15 sec

  5. On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

    Science.gov (United States)

    Klimas, Alexander J.; Fitzenreiter, Richard J.

    1988-01-01

    This paper presents further evidence for the persistence of bump-on-tail unstable reduced velocity distributions in the earth's electron foreshock, which contradicts the understanding of quasi-linear saturation of the bump-on-tail instability. A modified theory for the saturation of the bump-on-tail instability in the earth's foreshock is proposed to explain the mechanism of this persistence, and the predictions are compared to the results of a numerical simulation of the electron plasma in the foreshock. The results support the thesis that quasi-linear saturation of the bump-on-tail instability is modified in the foreshock, due to the driven nature of the region, so that at saturation the stabilized velocity distribution still appears bump-on-tail unstable to linear plasma analysis.

  6. Electron cyclotron maser instability in the solar corona - The role of superthermal tails

    Science.gov (United States)

    Vlahos, L.; Sharma, R. R.

    1985-01-01

    The effect of a superthermal component of electrons on the loss-cone-driven electron cyclotron maser instability is analyzed. It is found that for a superthermal tail with temperature about 10 KeV, the first harmonic (X- and O-mode) is suppressed for n(t)/n(r) of about 1 (n/t/ and n/r/ are the densities of superthermal tail and loss-cone electrons) and the second harmonic (X- and O-modes) is suppressed for n(t)/n(r) less than about 0.1. A qualitative discussion on the formation of superthermal tails is presented and it is suggested that superthermal tails play an important role on the observed or available power, at microwave frequencies, from the electron cyclotron maser instability in the solar corona.

  7. On the persistence of unstable bump-on-tail electron velocity distributions in the earth's foreshock

    International Nuclear Information System (INIS)

    Klimas, A.J.; Fitzenreiter, R.J.

    1988-01-01

    Further evidence for the persistence of bump-on-tail unstable reduced velocity distribution in the Earth's electron foreshock is presented. This persistence contradicts our understanding of quasi-linear saturation of the bump-on-tail instability; the distributions should be stabilized through velocity space diffusion too quickly to allow an observation of their unstable form. A modified theory for the saturation of the bump-on-tail instability in the Earth's foreshock is proposed and examined using numerical simulation and quasi-linear theoretical techniques. It is argued the mechanism due to Filbert and Kellogg and to Cairns which is responsible for the creation of the bump-on-tail velocity distribution in the foreshock is still operative during the evolution of the bump-on-tail instability. The saturated state of the plasma must represent a balance between this creation mechanism and velocity space diffusion; the saturated state is not determined by velocity space diffusion alone. Thus the velocity distribution of the saturated stat may still appear bump-on-tail unstable to standard linear analysis which does not take the creation mechanism into account. The bump-on-tail velocity distributions in the foreshock would then represent the state of the plasma after saturation of the bump-on-tail instability, not before

  8. A ray-tracing study of electron cyclotron resonance heating in Tokamak plasmas with a superthermal electron tail

    International Nuclear Information System (INIS)

    Montes, A.; Dendy, R.O.

    1987-09-01

    We consider a Tokamak plasma in which the distribution of electron velocities in the direction parallel to the magnetic field has a monotonically decreasing superthermal tail. A fully three-dimensional ray-tracing code, which includes a realistic antenna pattern, toroidal effects, and refaction, is used to calculate the absorption of the extraordinary mode in the nonrelativistic limit away from perpendicular incidence. The ray-tracing approach extends results previously obtained in slab geometry (3-8) to a more realistic configuration; it is also essential in dealing with strong refraction in high-density plasmas. Our analytical model for the tail makes available a wide range of tail shapes and parameters. At low densities small tails (tail fraction [pt

  9. Electron cyclotron maser instability in the solar corona: The role of superthermal tails

    International Nuclear Information System (INIS)

    Vlahos, L.; Sharma, R.R.

    1985-01-01

    The effect of a superthermal component of electrons on the loss-cone--driven electron cyclotron maser instability is analyzed. We found that for a supertheral tail with temperature approx.10 keV (i) the first harmonic (X- and O-mode) is suppressed for n/sub t//n/sub r/roughly-equal1 (n/sub t/ and n/sub r/ are the densities of superthermal tail and loss-cone electrons) and (ii) the second harmonic (X- and O-modes) is suppressed for n/sub t//n/sub r/ -1 . We present a qualitative discussion on the formation of superthermal taisl and suggest that superthermal tails play an important role on the observed or available power, at microwave frequencies, from the electron cyclotron maser instability in the solar corona

  10. Strong electron bidirectional anisotropies in the distant tail: ISEE 3 observations of polar rain

    International Nuclear Information System (INIS)

    Baker, D.N.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Zwickl, R.D.; Slavin, J.A.; Smith, E.J.

    1986-01-01

    A detailed observational treatment of bidirectional electrons (--50 to 50 eV)in the distant magnetotail (rapprox. >100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE 3 data provide extensive sampling of both the north and south lobes in rapid succession. These data demonstrate directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward interplanetary magnetic field in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Thus we demonstrate the open nature of the distant magnetopause and show that the source of the higher-energy, bidirectional lobe electrons is the tailward directed electron heat flux population in the distant magnetosheath. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is composed largely of open magnetic field lines in contradistinction to some recently advanced models

  11. Bidirectional electron anisotropies in the distant tail: ISEE-3 observations of polar rain

    International Nuclear Information System (INIS)

    Baker, D.N.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Zwickl, R.D.; Slavin, J.A.; Smith, E.J.

    1985-01-01

    A detailed observational treatment of bidirectional electrons (50 approx.500 eV) in the distant magnetotail (r greater than or equal to 100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE-3 data provide extensive sampling of both the north and south lobes in rapid succession, demonstrating directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward IMF in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is comprised largely of open magnetic field lines in contradistinction to some recently advanced models

  12. Simulation of tail distributions in electron-positron circular colliders

    International Nuclear Information System (INIS)

    Irwin, J.

    1992-02-01

    In addition to the Gaussian shaped core region, particle bunches in electron-positron circular colliders have a rarefied halo region of importance in determining beam lifetimes and backgrounds in particle detectors. A method is described which allows simulation of halo particle distributions

  13. Fokker-Planck simulation of runaway electron generation in disruptions with the hot-tail effect

    Energy Technology Data Exchange (ETDEWEB)

    Nuga, H., E-mail: nuga@p-grp.nucleng.kyoto-u.ac.jp; Fukuyama, A. [Department of Engineering, Kyoto University, Kyoto 615-8540 (Japan); Yagi, M. [National Institutes for Quantum and Radiological Science and Technology, Aomori 039-3212 (Japan)

    2016-06-15

    To study runaway electron generation in disruptions, we have extended the three-dimensional (two-dimensional in momentum space; one-dimensional in the radial direction) Fokker-Planck code, which describes the evolution of the relativistic momentum distribution function of electrons and the induced toroidal electric field in a self-consistent manner. A particular focus is placed on the hot-tail effect in two-dimensional momentum space. The effect appears if the drop of the background plasma temperature is sufficiently rapid compared with the electron-electron slowing down time for a few times of the pre-quench thermal velocity. It contributes to not only the enhancement of the primary runaway electron generation but also the broadening of the runaway electron distribution in the pitch angle direction. If the thermal energy loss during the major disruption is assumed to be isotropic, there are hot-tail electrons that have sufficiently large perpendicular momentum, and the runaway electron distribution becomes broader in the pitch angle direction. In addition, the pitch angle scattering also yields the broadening. Since the electric field is reduced due to the burst of runaway electron generation, the time required for accelerating electrons to the runaway region becomes longer. The longer acceleration period makes the pitch-angle scattering more effective.

  14. Electron cyclotron wave absorption by the fast tail generated by the dc electric field in tokamak plasmas

    International Nuclear Information System (INIS)

    Giruzzi, G.; Krivenski, V.; Fidone, I.; Ziebell, L.F.

    1985-03-01

    Wave damping near the electron gyrofrequency in a tokamak plasma with the energetic tail generated by the dc electric field is investigated. The electron tail is computed by a Fokker-Planck initial value code as a function of the relevant parameter Esub(parallel)/Esub(c)=Esub(parallel)Tsub(e)/(2πsub(e)c 3 Λ). It is shown that in most cases of physical interest strong damping of the e-mode occurs for oblique propagation. The results are of relevance for studies of ECRH in present-day tokamaks and in future reactors where a mildly relativistic electron tail is naturally present for large tsub(e). Special emphasis is therefore given to wave absorption for frequencies f significantly below the central electron gyrofrequency, and to the associated rf-driven current

  15. Piezoelectric energy harvesting from colored fat-tailed fluctuations: An electronic analogy

    Directory of Open Access Journals (Sweden)

    J. I. Peña Rosselló

    2015-09-01

    Full Text Available Aiming to optimize piezoelectric energy harvesting from strongly col-ored fat-tailed fluctuations, we have recently studied the performance ofa monostable inertial device under a noise whose statistics depends on aparameter q (bounded for q 1.We have studied the interplay between the potential shape (interpolatingbetween square-well and harmonic-like behaviors and the noise’s statis-tics and spectrum, and showed that its output power grows as q increasesabove 1. We now report a real experiment on an electronic analog of theproposed system, which sheds light on its operating principle. Received: 20 Novembre 2014, Accepted: 7 September 2015; Edited by: C. A. Condat, G. J. Sibona; DOI:http://dx.doi.org/10.4279/PIP.070014 Cite as: J I Peña Rosselló, R Deza, J . Deza, H S Wio, Papers in Physics 7, 070014 (2015

  16. Simulation studies of plasma waves in the electron foreshock - The generation of Langmuir waves by a gentle bump-on-tail electron distribution

    Science.gov (United States)

    Dum, C. T.

    1990-01-01

    Particle simulation experiments were used to study the basic physical ingredients needed for building a global model of foreshock wave phenomena. In particular, the generation of Langmuir waves by a gentle bump-on-tail electron distribution is analyzed. It is shown that, with appropriately designed simulations experiments, quasi-linear theory can be quantitatively verified for parameters corresponding to the electron foreshock.

  17. Electrons in feldspar II: A consideration of the influence of conduction band-tail states on luminescence processes

    DEFF Research Database (Denmark)

    Poolton, H.R.J.; Ozanyan, K.B.; Wallinga, J.

    2002-01-01

    consider what influence the band tails have on the luminescence properties of feldspar, where electrons travel through the sample prior to recombination. The work highlights the dominant role that 0.04-0.05-eV phonons play in both the luminescence excitation and emission processes of these materials...

  18. The INTERBALL-Tail ELECTRON experiment: initial results on the low-latitude boundary layer of the dawn magnetosphere

    Directory of Open Access Journals (Sweden)

    J.-A. Sauvaud

    Full Text Available The Toulouse electron spectrometer flown on the Russian project INTERBALL-Tail performs electron measurements from 10 to 26 000 eV over a 4 solid angle in a satellite rotation period. The INTERBALL-Tail probe was launched on 3 August 1995 together with a subsatellite into a 65° inclination orbit with an apogee of about 30 RE. The INTERBALL mission also includes a polar spacecraft launched in August 1996 for correlated studies of the outer magnetosphere and of the auroral regions. We present new observations concerning the low-latitude boundary layers (LLBL of the magnetosphere obtained near the dawn magnetic meridian. LLBL are encountered at the interface between two plasma regimes, the magnetosheath and the dayside extension of the plasma sheet. Unexpectedly, the radial extent of the region where LLBL electrons can be sporadically detected as plasma clouds can reach up to 5 RE inside the magnetopause. The LLBL core electrons have an average energy of the order of 100 eV and are systematically field-aligned and counterstreaming. As a trend, the temperature of the LLBL electrons increases with decreasing distance to Earth. Along the satellite orbit, the apparent time of occurrence of LLBL electrons can vary from about 5 to 20 min from one pass to another. An initial first comparison between electron- and magnetic-field measurements indicates that the LLBL clouds coincide with a strong increase in the magnetic field (by up to a factor of 2. The resulting strong magnetic field gradient can explain why the plasma-sheet electron flux in the keV range is strongly depressed in LLBL occurrence regions (up to a factor of sim10. We also show that LLBL electron encounters are related to field-aligned current structures and that wide LLBL correspond to northward interplanetary magnetic field. Evidence for LLBL/plasma-sheet electron leakage into the magnetosheath during southward IMF is also presented.

  19. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    Energy Technology Data Exchange (ETDEWEB)

    Etemadpour, R.; Dorranian, D., E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Sepehri Javan, N. [Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil (Iran, Islamic Republic of)

    2016-05-15

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  20. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    International Nuclear Information System (INIS)

    Etemadpour, R.; Dorranian, D.; Sepehri Javan, N.

    2016-01-01

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  1. Conformational dynamics of semiflexibly bridged electron donor-acceptor systems comprising long aliphatic tails

    NARCIS (Netherlands)

    Bleisteiner, B.; Marian, T.; Schneider, S.; Brouwer, A.M.; Verhoeven, J.W.

    2001-01-01

    In continuation of our previous work on the conformational dynamics (harpooning mechanism) of semiflexibly bridged electron donor-acceptor systems we have studied a derivative with two long aliphatic chains tethered to the donor and acceptor moieties, respectively. The fitting of the time- and

  2. A transmission electron microscopy analysis of secondary minerals formed in tungsten-mine tailings with an emphasis on arsenopyrite oxidation

    International Nuclear Information System (INIS)

    Petrunic, B.M.; Al, T.A.; Weaver, L.

    2006-01-01

    Grains of naturally oxidized arsenopyrite [FeAsS] collected from the oxidation zone in W-mine tailings were investigated, primarily using transmission electron microscopy. The grains are severely pitted and are surrounded by secondary minerals. The pitted nature of the grains is related to mechanisms governing the electrochemical oxidation of sulfide minerals, with prominent cusp-like features occurring at cathodic regions of the surface, and pits occurring at anodic regions. In general, the oxidation of arsenopyrite leads to the formation of an amorphous (or nanocrystalline) Fe-As-O-rich coating that contains small amounts of Si, Ca, Cu, Zn, Pb and Bi; nanoscale variation in the As, Pb, Bi and Zn contents of the coating was noted. Secondary Cu sulfides, thought to be chalcocite [Cu 2 S] and (or) djurleite [Cu 31 S 16 ], occur as a layer (generally 4 ] and an unidentified crystalline Bi-Pb-As-O mineral occur in voids within the coating, suggesting that these minerals precipitated from the local pore-water. Small and variable amounts of W, Ca, Bi, As and Zn are associated with the wulfenite, and Zn, Fe and Ca are associated with the Bi-Pb-As-O mineral. Some of the wulfenite is in contact with inclusions of molybdenite [MoS 2 ], suggesting that the oxidation of molybdenite in the presence of aqueous Pb(II) led to the formation of wulfenite. Mineralogical analyses at the nanoscale have improved the understanding of geochemical sources and sinks at this location. The results of this study indicate that the mineralogical controls on aqueous elemental concentrations at this tailings site are complex and are not predicted by thermodynamic calculations

  3. Tail state-assisted charge injection and recombination at the electron-collecting interface of P3HT:PCBM bulk-heterojunction polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, He [Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544 (United States); Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (United States); Shah, Manas [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ganesan, Venkat [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States); Chabinyc, Michael L. [Materials Department, University of California Santa Barbara, CA 93106 (United States); Loo, Yueh-Lin [Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2012-12-15

    The systematic insertion of thin films of P3HT and PCBM at the electron- and hole-collecting interfaces, respectively, in bulk-heterojunction polymer solar cells results in different extents of reduction in device characteristics, with the insertion of P3HT at the electron-collecting interface being less disruptive to the output currents compared to the insertion of PCBM at the hole-collecting interface. This asymmetry is attributed to differences in the tail state-assisted charge injection and recombination at the active layer-electrode interfaces. P3HT exhibits a higher density of tail states compared to PCBM; holes in these tail states can thus easily recombine with electrons at the electron-collection interface during device operation. This process is subsequently compensated by the injection of holes from the cathode into these tail states, which collectively enables net current flow through the polymer solar cell. The study presented herein thus provides a plausible explanation for why preferential segregation of P3HT to the cathode interface is inconsequential to device characteristics in P3HT:PCBM bulk-heterojunction solar cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor: structure, tail states and strain effects

    International Nuclear Information System (INIS)

    De Jamblinne de Meux, A; Genoe, J; Heremans, P; Pourtois, G

    2015-01-01

    We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen–metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced

  5. Simulation studies of plasma waves in the electron foreshock: The generation of Langmuir waves by a gentle bump-on-tail electron distribution

    International Nuclear Information System (INIS)

    Dum, C.T.

    1990-01-01

    The generation of Langmuir waves by a gentle bump-on-tail electron distribution is analyzed. It is shown that with appropriately designed simulation experiments, quasi-linear theory can be quantitatively verified for parameters corresponding to the electron foreshock. The distribution function develops a plateau by resonant diffusion, and changes outside this velocity range are negligible, except for the contribution of nonresonant diffusion to acceleration of bulk electrons. The dispersion relation is solved for the evolving distribution function and exhibits the dynamics of wave growth and changes in real frequency. The integral of the quasi-linear equations is also used to relate the evolution of distribution function and wave spectrum and gives agreement with the simulations. Even in extremely long simulation runs there is practically no evolution in wave energy or the distribution function, once a plateau has been formed. the saturated field levels are much lower than the estimates that are generally used to assess the importance of additional weak or strong turbulence effects. These effects cannot prevent plateau formation and are only noticeable if ions are also included in the model. They then lead to a redistribution of the spectrum toward low wave number modes which propagate mainly opposite to the beam. This occurs long after plateau formation and plays no significant role in the overall system dynamics or energy balance. One will have to live with quasi-linear theory as a key ingredient for a global model of foreshock wave phenomena

  6. A transmission electron microscopy analysis of secondary minerals formed in tungsten-mine tailings with an emphasis on arsenopyrite oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Petrunic, B.M. [Department of Geology, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada)]. E-mail: petrunic@gmail.com; Al, T.A. [Department of Geology, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada); Weaver, L. [Microscopy and Microanalysis Facility, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada)

    2006-08-15

    Grains of naturally oxidized arsenopyrite [FeAsS] collected from the oxidation zone in W-mine tailings were investigated, primarily using transmission electron microscopy. The grains are severely pitted and are surrounded by secondary minerals. The pitted nature of the grains is related to mechanisms governing the electrochemical oxidation of sulfide minerals, with prominent cusp-like features occurring at cathodic regions of the surface, and pits occurring at anodic regions. In general, the oxidation of arsenopyrite leads to the formation of an amorphous (or nanocrystalline) Fe-As-O-rich coating that contains small amounts of Si, Ca, Cu, Zn, Pb and Bi; nanoscale variation in the As, Pb, Bi and Zn contents of the coating was noted. Secondary Cu sulfides, thought to be chalcocite [Cu{sub 2}S] and (or) djurleite [Cu{sub 31}S{sub 16}], occur as a layer (generally <500 nm thick) along the arsenopyrite grain boundary, and also within the coating as aggregates, and as layers that parallel the grain boundary. Although the precipitation of secondary Cu minerals along the grain boundary is a nanoscale feature, the process of formation is thought to be analogous to the supergene enrichment that occurs in weathered sulfide deposits. As the oxidation of arsenopyrite proceeds, layers and clusters of secondary Cu sulfides become isolated in the Fe-As-O coating. Secondary wulfenite [PbMoO{sub 4}] and an unidentified crystalline Bi-Pb-As-O mineral occur in voids within the coating, suggesting that these minerals precipitated from the local pore-water. Small and variable amounts of W, Ca, Bi, As and Zn are associated with the wulfenite, and Zn, Fe and Ca are associated with the Bi-Pb-As-O mineral. Some of the wulfenite is in contact with inclusions of molybdenite [MoS{sub 2}], suggesting that the oxidation of molybdenite in the presence of aqueous Pb(II) led to the formation of wulfenite. Mineralogical analyses at the nanoscale have improved the understanding of geochemical sources

  7. Research on Long Tail Recommendation Algorithm

    Science.gov (United States)

    Hu, Xuezhi; Zhang, Chuang; Wu, Ming; Zeng, Yang

    2017-10-01

    Most recommendation systems in the major electronic commerce platforms are influenced by the long tail effect more or less. There are sufficient researches of how to assess recommendation effect while no criteria to evaluate long tail recommendation rate. In this study, we first discussed the existing problems of recommending long tail products through specific experiments. Then we proposed a long tail evaluation criteria and compared the performance in long tail recommendation between different models.

  8. Runaway tails in magnetized plasmas

    Science.gov (United States)

    Moghaddam-Taaheri, E.; Vlahos, L.; Rowland, H. L.; Papadopoulos, K.

    1985-01-01

    The evolution of a runaway tail driven by a dc electric field in a magnetized plasma is analyzed. Depending on the strength of the electric field and the ratio of plasma to gyrofrequency, there are three different regimes in the evolution of the tail. The tail can be (1) stable with electrons accelerated to large parallel velocities, (2) unstable to Cerenkov resonance because of the depletion of the bulk and the formation of a positive slope, (3) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the tail. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the tail relaxes into an isotropic distribution. The role of a convection type loss term is also discussed.

  9. High-Performance n-Channel Organic Transistors Using High-Molecular-Weight Electron-Deficient Copolymers and Amine-Tailed Self-Assembled Monolayers.

    Science.gov (United States)

    Wang, Yang; Hasegawa, Tsukasa; Matsumoto, Hidetoshi; Mori, Takehiko; Michinobu, Tsuyoshi

    2018-03-01

    While high-performance p-type semiconducting polymers are widely reported, their n-type counterparts are still rare in terms of quantity and quality. Here, an improved Stille polymerization protocol using chlorobenzene as the solvent and palladium(0)/copper(I) as the catalyst is developed to synthesize high-quality n-type polymers with number-average molecular weight up to 10 5 g mol -1 . Furthermore, by sp 2 -nitrogen atoms (sp 2 -N) substitution, three new n-type polymers, namely, pBTTz, pPPT, and pSNT, are synthesized, and the effect of different sp 2 -N substitution positions on the device performances is studied for the first time. It is found that the incorporation of sp 2 -N into the acceptor units rather than the donor units results in superior crystalline microstructures and higher electron mobilities. Furthermore, an amine-tailed self-assembled monolayer (SAM) is smoothly formed on a Si/SiO 2 substrate by a simple spin-coating technique, which can facilitate the accumulation of electrons and lead to more perfect unipolar n-type transistor performances. Therefore, a remarkably high unipolar electron mobility up to 5.35 cm 2 V -1 s -1 with a low threshold voltage (≈1 V) and high on/off current ratio of ≈10 7 is demonstrated for the pSNT-based devices, which are among the highest values for unipolar n-type semiconducting polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Tail gut cyst.

    Science.gov (United States)

    Rao, G Mallikarjuna; Haricharan, P; Ramanujacharyulu, S; Reddy, K Lakshmi

    2002-01-01

    The tail gut is a blind extension of the hindgut into the tail fold just distal to the cloacal membrane. Remnants of this structure may form tail gut cyst. We report a 14-year-old girl with tail gut cyst that presented as acute abdomen. The patient recovered after cyst excision.

  11. Galaxies with long tails

    International Nuclear Information System (INIS)

    Schweizer, F.

    1978-01-01

    Two types of galaxies with long tails are described. The first occurs in pairs, each individual one having a long tail and the second occurs on its own with two tails. NGC 7252 shows several characteristics which one would expect of a merger: a pair of tidal tails despite the splendid isolation, a single nucleus, tail motions in opposite directions relative to the nucleus, and chaotic motions of a strangely looped main body. (C.F.)

  12. Characterization of oils sands thickened tailings

    Energy Technology Data Exchange (ETDEWEB)

    Scott, J.D.; Jeeravipoolvarn, S.; Donahue, R.; Ozum, B. [Alberta Univ., Edmonton, AB (Canada). Dept. of Civil and Environmental Engineering

    2008-07-01

    This presentation discussed the characterization of oils sands thickened tailings. The problem statement was defined as the fact that many laboratory procedures to characterize fine tailings do not take into account the extraction process, and instead use standardized laboratory tests. The purpose of this presentation was to demonstrate how different extraction processes affect the fine tailings geotechnical properties and water chemistry. Properties that were characterized included particle size analysis from hydrometer-sieve tests; per cent clay from methylene blue tests; per cent clay from mineralogy tests; Atterberg limits; water chemistry; and morphology by scanning electron microscopy. The presentation discussed the origin of fines (silt and clay) in tailings; where fine particles come from; tailings materials; mineralogy of tailings; the hydrometer-sieve test on fine tailings and thickened tailings; and the methylene blue test. It was concluded that the great majority of clay minerals in the tailings come from the clay-shale discontinuous seams and layers. For thickened tailings, the dispersed and non-dispersed hydrometer tests show considerable difference in the amount of clay size material. tabs., figs.

  13. Uranium Mill Tailings Management

    International Nuclear Information System (INIS)

    Nelson, J.D.

    1982-01-01

    This book presents the papers given at the Fifth Symposium on Uranium Mill Tailings Management. Advances made with regard to uranium mill tailings management, environmental effects, regulations, and reclamation are reviewed. Topics considered include tailings management and design (e.g., the Uranium Mill Tailings Remedial Action Project, environmental standards for uranium mill tailings disposal), surface stabilization (e.g., the long-term stability of tailings, long-term rock durability), radiological aspects (e.g. the radioactive composition of airborne particulates), contaminant migration (e.g., chemical transport beneath a uranium mill tailings pile, the interaction of acidic leachate with soils), radon control and covers (e.g., radon emanation characteristics, designing surface covers for inactive uranium mill tailings), and seepage and liners (e.g., hydrologic observations, liner requirements)

  14. Heavy tails of OLS

    DEFF Research Database (Denmark)

    Mikosch, Thomas Valentin; de Vries, Casper

    2013-01-01

    Suppose the tails of the noise distribution in a regression exhibit power law behavior. Then the distribution of the OLS regression estimator inherits this tail behavior. This is relevant for regressions involving financial data. We derive explicit finite sample expressions for the tail probabili...

  15. Consolidation of tailings

    International Nuclear Information System (INIS)

    Nelson, J.D.; Wardwell, R.E.; Abt, S.R.; Staub, W.P.

    1983-09-01

    The integrity of cover systems placed on tailings impoundments will be affected by the potential for differential settlement of the tailings surface. Settlement of the sand fraction will occur relatively rapidly. The slimes will take longer time for consolidation and will produce greater settlement. This report reviews the phenomenon of consolidation for saturated and unsaturated tailings. The effect of load application by cover placement and the extent to which dewatering of tailings will cause consolidation are considered. In addition, the feasibility of inducing consolidation by alternative means and the potential applicability of these methods to tailings impoundments reclamation are discussed. Differential settlement of the tailings will cause tensile strain to be developed in covers. This strain could be large enough to cause cracking within a relatively brittle compacted clay. Dewatering of tailings by drainage can cause settlement even greater than that by placement of a cover material. Dewatering of the tailings would also increase the stability of the tailings surface, thereby enhancing reclamation operations. Consequently, in view of the enhanced surface stability and the fact that a portion of the differential settlement can be accomplished prior to cover placement, dewatering of tailings impoundments during operations may have benefical effects

  16. Uranium tailings bibliography

    International Nuclear Information System (INIS)

    Holoway, C.F.; Goldsmith, W.A.; Eldridge, V.M.

    1975-12-01

    A bibliography containing 1,212 references is presented with its focus on the general problem of reducing human exposure to the radionuclides contained in the tailings from the milling of uranium ore. The references are divided into seven broad categories: uranium tailings pile (problems and perspectives), standards and philosophy, etiology of radiation effects, internal dosimetry and metabolism, environmental transport, background sources of tailings radionuclides, and large-area decontamination

  17. Uranium tailings sampling manual

    International Nuclear Information System (INIS)

    Feenstra, S.; Reades, D.W.; Cherry, J.A.; Chambers, D.B.; Case, G.G.; Ibbotson, B.G.

    1985-01-01

    The purpose of this manual is to describe the requisite sampling procedures for the application of uniform high-quality standards to detailed geotechnical, hydrogeological, geochemical and air quality measurements at Canadian uranium tailings disposal sites. The selection and implementation of applicable sampling procedures for such measurements at uranium tailings disposal sites are complicated by two primary factors. Firstly, the physical and chemical nature of uranium mine tailings and effluent is considerably different from natural soil materials and natural waters. Consequently, many conventional methods for the collection and analysis of natural soils and waters are not directly applicable to tailings. Secondly, there is a wide range in the physical and chemical nature of uranium tailings. The composition of the ore, the milling process, the nature of tailings depositon, and effluent treatment vary considerably and are highly site-specific. Therefore, the definition and implementation of sampling programs for uranium tailings disposal sites require considerable evaluation, and often innovation, to ensure that appropriate sampling and analysis methods are used which provide the flexibility to take into account site-specific considerations. The following chapters describe the objective and scope of a sampling program, preliminary data collection, and the procedures for sampling of tailings solids, surface water and seepage, tailings pore-water, and wind-blown dust and radon

  18. Uranium mill tailings management

    International Nuclear Information System (INIS)

    1982-01-01

    Facilities for the disposal of uranium mill tailings will invariably be subjected to geomorphological and climatological influences in the long-term. Proceedings of a workshop discuss how the principles of geomorphology can be applied to the siting, design, construction, decommissioning and rehabilitation of disposal facilities in order to provide for long-term containment and stability of tailings. The characteristics of tailings and their behaviour after disposal influence the potential impacts which might occur in the long-term. Proceedings of another workshop examine the technologies for uranium ore processing and tailings conditioning with a view to identifying improvements that could be made in such characteristics

  19. Tales of island tails

    NARCIS (Netherlands)

    Groot, de Alma V.; Oost, Albert P.; Veeneklaas, Roos M.; Lammerts, Evert Jan; Duin, van Willem E.; Wesenbeeck, van Bregje K.

    2016-01-01

    The Frisian islands (Southern North Sea) have extensive island tails, i.e. the entire downdrift side of an island consisting of salt marshes, dunes, beaches and beach plains, and green beaches. Currently, large parts of these tails are ageing and losing dynamics, partly due to human influence.

  20. Bar-tailed

    NARCIS (Netherlands)

    Duijns, S.; Hidayati, N.A.; Piersma, T.

    2013-01-01

    Capsule Across the European wintering range Bar-tailed Godwits Limosa lapponica lapponica selected polychaete worms and especially Ragworms Hediste diversicolor, with differences between areas due to variations in prey availability.Aims To determine the diet of Bar-tailed Godwits across their

  1. Tailings management at Nabarlek

    International Nuclear Information System (INIS)

    Waggitt, P.

    1989-01-01

    As the entire uranium deposit at Nabarlek was mined in 1979, the mine pit was available as a tailing's repository from the time of commencement of ore processing. In the early years Nabarlek's tailings were deposited subaqueously. In 1985 the tailings deposition method was changed to a sub-aerial, or semi-dry, method. Over the subsequent three years there was evidence that the tailings settled further and squeezed water from lower layers. The water was pumped away and treated for removal of radium before being evaporated in one of the mine's evaporation ponds. When milling was completed in 1988 it was decided to try and increase the rate of water removal and so obtain even greater consolidation of the trailings in a shorter time. This was achieved by loading the tailings with a layer of screened leached sands and waste rock placed on a layer of geotextile filter fabric that had been laid over the whole of the tailings surface in the pit. Once this was completed a modified piling rig was used to insert vertical drains, or wicks, up to 30 metres into the tailings. The drains were placed on a square grid at a spacing of 3.25 metres. Water that was forced out of the tailings by the downward pressure of the sand and rock could flow freely to the surface up these drains. Once at the surface the water was gathered into a sump and pumped away for treatment as before. The drains are working very well at present although it will be some considerable time before the water stops flowing. Already settlement of the tailings is apparent and the settled density of the material is increasing. As far as is known this is the first time that such a system has been employed on mine tailings in a pit in this way

  2. Characterization and monitoring of transverse beam tails

    International Nuclear Information System (INIS)

    Seeman, J.T.; Decker, F.J.; Hsu, I.; Young, C.

    1991-05-01

    Low emittance electron beams accelerated to high energy in a linac experience transverse effects (wakefield, filamentation, optics) which produce non-Gaussian projected transverse beam distributions. Characterizations of the beam shapes are difficult because the shapes are asymmetric and change with betatron phase. In this note several methods to describe beam distributions are discussed including an accelerator physics model of these tails. The uses of these characterizations in monitoring the beam emittances in the SLC are described in this paper. First, two dimensional distributions from profile monitor screens are reviewed showing correlated tails. Second, a fitting technique for non-Gaussian one dimensional distributions is used to extract the core from the tail areas. Finally, a model for tail propagation in the linac is given. 3 refs., 6 figs

  3. Frost evolution in tailings

    International Nuclear Information System (INIS)

    1991-04-01

    A review was carried out on the physical and thermal mechanisms of permafrost evaluation in soils and uranium tailings. The primary mechanism controlling permafrost evolution is conductive heat transfer with the latent heat of fusion of water being liberated as phase change occurs. Depending on the soil properties and freezing rate, pore water can be expelled from the frost front or pore water can migrate towards the frost front. Solute redistribution may occur as the frost front penetrates into the soil. The rate of frost penetration is a function of the thermal properties of the tailings and the climatic conditions. Computer modelling programmes capable of modelling permafrost evolution were reviewed. The GEOTHERM programme was selected as being the most appropriate for this study. The GEOTHERM programme uses the finite element method of thermal analysis. The ground surface temperature is determined by solving the energy balance equations a the ground surface. The GEOTHERM programme was used to simulate the permafrost evolution in the Key Lake Mine tailings located in north central Saskatchewan. The analyses indicated that the existing frozen zones in the tailing pond will eventually thaw if an average snow depth covers the tailings. Hundreds of years are required to thaw the tailings. If minimal snow cover is present the extent of the frozen zone in the tailings will increase

  4. The Tail of BPM

    Science.gov (United States)

    Kruba, Steve; Meyer, Jim

    Business process management suites (BPMS's) represent one of the fastest growing segments in the software industry as organizations automate their key business processes. As this market matures, it is interesting to compare it to Chris Anderson's 'Long Tail.' Although the 2004 "Long Tail" article in Wired magazine was primarily about the media and entertainment industries, it has since been applied (and perhaps misapplied) to other markets. Analysts describe a "Tail of BPM" market that is, perhaps, several times larger than the traditional BPMS product market. This paper will draw comparisons between the concepts in Anderson's article (and subsequent book) and the BPM solutions market.

  5. Estimation of Jump Tails

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Victor

    We propose a new and flexible non-parametric framework for estimating the jump tails of Itô semimartingale processes. The approach is based on a relatively simple-to-implement set of estimating equations associated with the compensator for the jump measure, or its "intensity", that only utilizes...... the weak assumption of regular variation in the jump tails, along with in-fill asymptotic arguments for uniquely identifying the "large" jumps from the data. The estimation allows for very general dynamic dependencies in the jump tails, and does not restrict the continuous part of the process...... and the temporal variation in the stochastic volatility. On implementing the new estimation procedure with actual high-frequency data for the S&P 500 aggregate market portfolio, we find strong evidence for richer and more complex dynamic dependencies in the jump tails than hitherto entertained in the literature....

  6. Tail posture predicts tail damage among weaned piglets

    NARCIS (Netherlands)

    Zonderland, J.J.; Riel, van J.W.; Bracke, M.B.M.; Kemp, B.; Hartog, den L.A.; Spoolder, H.A.M.

    2009-01-01

    Tail biting in pigs is a widespread behavioural vice with significant animal welfare and economic consequences. All too often, tail biting is not diagnosed nor dealt with until tail damage is present. To effectively reduce the negative effects of tail biting, it must be diagnosed in an early stage.

  7. Markov Tail Chains

    OpenAIRE

    janssen, Anja; Segers, Johan

    2013-01-01

    The extremes of a univariate Markov chain with regularly varying stationary marginal distribution and asymptotically linear behavior are known to exhibit a multiplicative random walk structure called the tail chain. In this paper we extend this fact to Markov chains with multivariate regularly varying marginal distributions in Rd. We analyze both the forward and the backward tail process and show that they mutually determine each other through a kind of adjoint relation. In ...

  8. Uranium mill tailings stabilization

    International Nuclear Information System (INIS)

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

    1980-02-01

    Uranium mill tailings pose a potential radiation health hazard to the public. Therefore, stabilization or disposal of these tailings in a safe and environmentally sound way is needed to minimize radon exhalation and other environmental hazards. One of the most promising concepts for stabilizing U tailings is the use of asphalt emulsion to contain radon and other hazardous materials within uranium tailings. This approach is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admixture seal (2.5 to 12.7 cm thick) containing about 18 wt % residual asphalt. A field test was carried out in June 1979 at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 15.2-cm (6-in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer was used to apply the admix. Following compaction, a spray coat seal was applied over the admix as the final step in construction of a radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration

  9. Liquefaction of uranium tailings

    International Nuclear Information System (INIS)

    1992-02-01

    Numerical methods for assessing the liquefaction potential of soils are reviewed with a view to their application to uranium tailings. The method can be divided into two categories: total stress analysis, where changes in pore pressure are not considered in the soil model, and effective stress analysis, where changes in pore pressure are included in the soil model. Effective stress analysis is more realistic, but few computer programs exist for such analysis in two or three dimensions. A simple linearized, two-dimensional, finite element effective stress analysis which incorporates volumetric compaction due to shear motion is described and implemented. The new program is applied to the assessment of liquefaction potential of tailings in the Quirke Mine tailings area near Elliot Lake, Ontario. The results are compared with those of a total stress analysis. Both analyses indicate liquefaction would occur if a magnitude 6.0 earthquake were to occur near the area. However, the extent of liquefaction predicted by the effective stress analysis is much less than that predicted by the total stress analysis. The results of both methods are sensitive to assumed material properties and to the method used to determine the cyclic shear strength of the tailings. Further analysis, incorporating more in situ and/or laboratory data, is recommended before conclusions can be made concerning the dynamic stability of these tailings

  10. Mine tailings disposal

    International Nuclear Information System (INIS)

    Gonzales, P.A.; Adams, B.J.

    1980-06-01

    The hydrologic evaluation of mine tailings disposal sites after they are abandoned is considered in relation to their potential environmental impact on a long term basis. There is a direct relation between the amounts and types of water leaving a disposal site and the severity of the potential damage to the environment. The evaluation of the relative distribution of the precipitation reaching the ground into evaporation, runoff and infiltration is obtained for a selected site and type of tailings material whose characteristics and physical properties were determined in the soils laboratory. A conceptual model of the hydrologic processes involved and the corresponding mathematical model were developed to simulate the physical system. A computer program was written to solve the set of equations forming the mathematical model, considering the physical properties of the tailings and the rainfall data selected. The results indicate that the relative distribution of the precipitation depends on the surface and upper layer of the tailings and that the position of the groundwater table is governed by the flow through the bottom of the profile considered. The slope of the surface of the mass of tailings was found to be one of the principal factors affecting the relative distribution of precipitation and, therefore, the potential pollution of the environment

  11. Uranium mill tailings

    International Nuclear Information System (INIS)

    McLaren, L.H.

    1982-11-01

    This bibliography contains information on uranium mill tailings included in the Department of Energy's Energy Data Base from January 1981 through October 1982. The abstracts are grouped by subject category as shown in the table of contents. Entries in the subject index also facilitate access by subject, e.g., Mill Tailings/Radiation Hazards. Within each category the arrangement is by report number for reports, followed by nonreports in reverse chronological order. These citations are to research reports, journal articles, books, patents, theses, and conference papers from worldwide sources. Five indexes, each preceded by a brief description, are provided: Corporate Author, Personal Author, Subject, Contract Number, and Report Number. (335 abstracts)

  12. Managing 'tail liability'.

    Science.gov (United States)

    Frese, Richard C; Weber, Ryan J

    2013-11-01

    To reduce and control their level of tail liability, hospitals should: Utilize a self-insurance vehicle; Consider combined limits between the hospital and physicians; Communicate any program changes to the actuary, underwriter, and auditor; Continue risk management and safety practices; Ensure credit is given to the organization's own medical malpractice program.

  13. Uranium mill tailings conditioning technology

    International Nuclear Information System (INIS)

    Dreesen, D.R.; Cokal, E.J.; Wangen, L.E.; Williams, J.M.; O'Brien, P.D.; Thode, E.F.

    1982-01-01

    Conditioning of uranium mill tailings involves the physicochemical alteration of tailings to remove or immobilize mobile radionuclides and toxic trace elements before disposal in a repository. The principal immobilization approach under investigation is sintering tailings at high temperatures (1100-1200 deg. C) to radically alter the structure of tailings. This thermal stabilization at 1200 deg. C reduced radon emanation power for tailings sands by factors of 20 to 200 and for tailings fines by factors of 300 to 1100. Substantial reductions in the leachability of most contaminants have been found for thermally conditioned tailings. Obvious mineral transformations occur, including an increase in amorphous material, the conversion of gypsum to anhydrite and its subsequent decomposition, the disappearance of clay minerals, and some decrease in quartz content. A conceptual thermal stabilization process has been developed wherein obsolete coal-fired rotary cement kilns perform the sintering. An economic analysis of this conceptual process has shown that thermal stabilization can be competitive at certain tailings sites with other remedial actions requiring the excavation, transportation, and burial of tailings in a repository. An analysis of the long-term radiological hazard posed by untreated tailings and by tailings conditioned by radionuclide removal has illustrated the necessity of extracting both 226 Ra and 230 Th to achieve long-term hazard reductions. Sulphuric acid extraction of residual mineral values and important radionuclides from tailings has been investigated. Concentrated H 2 SO 4 can extract up to 80% of the 226 Ra, 70% of the Ba, and 90% of the 230 Th from tailings in a single stage extraction. An economic analysis of a sulphuric acid leach process was made to determine whether the value of minerals recovered from tailings would offset the leaching cost. For one relatively mineral-rich tailings pile, the U and V values would more than pay for the

  14. Telling tails: selective pressures acting on investment in lizard tails.

    Science.gov (United States)

    Fleming, Patricia A; Valentine, Leonie E; Bateman, Philip W

    2013-01-01

    Caudal autotomy is a common defense mechanism in lizards, where the animal may lose part or all of its tail to escape entrapment. Lizards show an immense variety in the degree of investment in a tail (i.e., length) across species, with tails of some species up to three or four times body length (snout-vent length [SVL]). Additionally, body size and form also vary dramatically, including variation in leg development and robustness and length of the body and tail. Autotomy is therefore likely to have fundamentally different effects on the overall body form and function in different species, which may be reflected directly in the incidence of lost/regenerating tails within populations or, over a longer period, in terms of relative tail length for different species. We recorded data (literature, museum specimens, field data) for relative tail length (n=350 species) and the incidence of lost/regenerating tails (n=246 species). We compared these (taking phylogeny into account) with intrinsic factors that have been proposed to influence selective pressures acting on caudal autotomy, including body form (robustness, body length, leg development, and tail specialization) and ecology (foraging behavior, physical and temporal niches), in an attempt to identify patterns that might reflect adaptive responses to these different factors. More gracile species have relatively longer tails (all 350 spp., P lost/regenerating tails for nocturnal lizards (all 246 spp., P pressure.

  15. Uranium tailings in Canada

    International Nuclear Information System (INIS)

    Boulden, R.S.; Bragg, K.

    1982-01-01

    The last few years have produced significant changes in the way uranium tailings are managed in Canada. This is due both to the development of new technology and to changes in regulatory approach. The interrelationships between these two areas are examined with particular attention paid to the long term and the development of close-out criteria. New technological initiatives are examined including dry placement techniques, pit disposal and deep lake disposal

  16. Injurious tail biting in pigs

    DEFF Research Database (Denmark)

    D'Eath, R.B.; Amott, G.; Turner, S. P.

    2014-01-01

    not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable...... substrates and feeder space affect damaging tail biting. Only epidemiological evidence was available for effects of temperature and season, and the effect of stocking density was unclear. Studies suggest that group size has little effect, and the effects of nutrition, disease and breed require further...... underlying processes of tail biting. A quantitative comparison of the efficacy of different methods of provision of manipulable materials, and a review of current practices in countries and assurance schemes where tail docking is banned, both suggest that daily provision of small quantities of destructible...

  17. Structural Conservation of the Myoviridae Phage Tail Sheath Protein Fold

    Energy Technology Data Exchange (ETDEWEB)

    Aksyuk, Anastasia A.; Kurochkina, Lidia P.; Fokine, Andrei; Forouhar, Farhad; Mesyanzhinov, Vadim V.; Tong, Liang; Rossmann, Michael G. (SOIBC); (Purdue); (Columbia)

    2012-02-21

    Bacteriophage phiKZ is a giant phage that infects Pseudomonas aeruginosa, a human pathogen. The phiKZ virion consists of a 1450 {angstrom} diameter icosahedral head and a 2000 {angstrom}-long contractile tail. The structure of the whole virus was previously reported, showing that its tail organization in the extended state is similar to the well-studied Myovirus bacteriophage T4 tail. The crystal structure of a tail sheath protein fragment of phiKZ was determined to 2.4 {angstrom} resolution. Furthermore, crystal structures of two prophage tail sheath proteins were determined to 1.9 and 3.3 {angstrom} resolution. Despite low sequence identity between these proteins, all of these structures have a similar fold. The crystal structure of the phiKZ tail sheath protein has been fitted into cryo-electron-microscopy reconstructions of the extended tail sheath and of a polysheath. The structural rearrangement of the phiKZ tail sheath contraction was found to be similar to that of phage T4.

  18. Settlement of uranium mill tailings

    International Nuclear Information System (INIS)

    Chen, P.K.; Guros, F.B.; Keshian, B.

    1988-01-01

    Two test embankments were constructed on top of an old tailings deposit near Ambrosia Lake, New Mexico to determine settlement characteristics of hydraulically- deposited uranium mill tailings. Before construction of the embankments, properties of in-situ tailings and foundation soils were determined using data from boreholes, piezocone soundings, and laboratory tests. These properties were used to estimate post-construction settlement of a planned disposal embankment to be constructed on the tailings. However, excessive uncertainty existed in the following: field settlement rates of saturated and unsaturated tailings, degree of preconsolidation of the upper 15 feet of tailings, and the ability of an underlying silty sand foundation layer to facilitate drainage. Thus, assurance could not be provided that differential settlements of the radon barrier and erosion protection layers would be within allowable limits should the planned disposal embankment be constructed in a single-stage

  19. Copper tailings in stucco mortars

    Directory of Open Access Journals (Sweden)

    Osvaldo Pavez

    Full Text Available Abstract This investigation addressed the evaluation of the use of copper tailings in the construction industry in order to reduce the impact on the environment. The evaluation was performed by a technical comparison between stucco mortars prepared with crushed conventional sand and with copper tailings sand. The best results were achieved with the stucco mortars containing tailings. The tailings presented a fine particles size distribution curve different from that suggested by the standard. The values of compressive strength, retentivity, and adherence in the stucco mortars prepared with copper tailings were much higher than those obtained with crushed sand. According to the results from this study, it can be concluded that the preparation of stucco mortars using copper tailings replacing conventional sand is a technically feasible alternative for the construction industry, presenting the benefit of mitigating the impact of disposal to the environment.

  20. Uranium tailings reference materials

    International Nuclear Information System (INIS)

    Smith, C.W.; Steger, H.F.; Bowman, W.S.

    1984-01-01

    Samples of uranium tailings from Bancroft and Elliot Lake, Ontario, and from Beaverlodge and Rabbit Lake, Saskatchewan, have been prepared as compositional reference materials at the request of the National Uranium Tailings Research Program. The four samples, UTS-1 to UTS-4, were ground to minus 104 μm, each mixed in one lot and bottled in 200-g units for UTS-1 to UTS-3 and in 100-g units for UTS-4. The materials were tested for homogeneity with respect to uranium by neutron activation analysis and to iron by an acid-decomposition atomic absorption procedure. In a free choice analytical program, 18 laboratories contributed results for one or more of total iron, titanium, aluminum, calcium, barium, uranium, thorium, total sulphur, and sulphate for all four samples, and for nickel and arsenic in UTS-4 only. Based on a statistical analysis of the data, recommended values were assigned to all elements/constituents, except for sulphate in UTS-3 and nickel in UTS-4. The radioactivity of thorium-230, radium-226, lead-210, and polonium-210 in UTS-1 to UTS-4 and of thorium-232, radium-228, and thorium-228 in UTS-1 and UTS-2 was determined in a radioanalytical program composed of eight laboratories. Recommended values for the radioactivities and associated parameters were calculated by a statistical treatment of the results

  1. Bioassay for uranium mill tailings

    International Nuclear Information System (INIS)

    Tschaeche, A.N.

    1986-01-01

    Uranium mill tailings are composed of fine sand that contains, among other things, some uranium (U/sup 238/ primarily), and all of the uranium daughters starting with /sup 230/Th that are left behind after the usable uranium is removed in the milling process. Millions of pounds of tailings are and continue to be generated at uranium mills around the United States. Discrete uranium mill tailings piles exist near the mills. In addition, the tailings materials were used in communities situated near mill sites for such purposes as building materials, foundations for buildings, pipe runs, sand boxes, gardens, etc. The Uranium Mill Tailings Remedial Action Project (UMTRAP) is a U.S. Department of Energy Program designed with the intention of removing or stabilizing the mill tailings piles and the tailings used to communities so that individuals are not exposed above the EPA limits established for such tailings materials. This paper discusses the bioassay programs that are established for workers who remove tailings from the communities in which they are placed

  2. Uranium mill tailings and radon

    International Nuclear Information System (INIS)

    Hanchey, L.A.

    1981-01-01

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the US may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action Program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100

  3. Uranium mill tailings and radon

    Energy Technology Data Exchange (ETDEWEB)

    Hanchey, L A

    1981-04-01

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the United States may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100.

  4. Uranium mill tailings and radon

    Energy Technology Data Exchange (ETDEWEB)

    Hanchey, L A

    1981-01-01

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the US may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action Program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100.

  5. TAIL ASYMPTOTICS OF LIGHT-TAILED WEIBULL-LIKE SUMS

    DEFF Research Database (Denmark)

    Asmussen, Soren; Hashorva, Enkelejd; Laub, Patrick J.

    2017-01-01

    We consider sums of n i.i.d. random variables with tails close to exp{-x(beta)} for some beta > 1. Asymptotics developed by Rootzen (1987) and Balkema, Kluppelberg, and Resnick (1993) are discussed from the point of view of tails rather than of densities, using a somewhat different angle...

  6. Effects of weather and tailings properties on tailings drying times

    Energy Technology Data Exchange (ETDEWEB)

    Gantzer, C.; Fasking, T.; Costello, M.; Greenwood, J. [Barr Engineering, Calgary, AB (Canada)

    2010-07-01

    This PowerPoint presentation presented the results of a study conducted to determine the effects of weather and tailings properties on tailings drying times. Weather conditions have a significant impact the potential evaporation (PE) and actual evaporation (AE) of oil sands tailings. A 2-stage drying of slurry at a constant PE was conducted to determine the shrinkage limit of untreated mature fine tailings (MFT). An evaporation and seepage model was used to determine maximum first-stage drying rates. Measurements were also taken in a wind tunnel. Potential evaporation rates were calculated and evaporative water losses from the MFT were determined. Estimated drying times were presented. Results of the approach were compared with field measurements conducted in a previous study. Results of the study showed that evaporative water loss rates for May through August were limited by the properties of the tailings. Water loss rates were limited by weather for other months in the year-long study. tabs., figs.

  7. Leachability of radioactive constituents from uranium mine tailings

    International Nuclear Information System (INIS)

    Constable, T.W.

    1987-04-01

    A series of long-term studies were conducted both to examine the leachability of major constituents (acidity, TDS) and radioisotopes from uranium mining/milling tailings and settling pond sludges, and to assess the effect of two treatment methods (solidification and vegetation) on leachate characteristics. Four bench-scale experiments were conducted to examine the leachability of: 1) old tailings and those containing a large portion of (Ba,Ra)SO 4 sludges; 2) untreated and solidified (Ba,Ra)SO 4 sludges located at the bottom of settling ponds; 3) new tailings that had been vegetated or solidified; and 4) new tailings subject to varying flow rates. A fifth study was conducted to examine the microbiology of Experiments 2 and 3. In addition, the lysimeter solids remaining in the old tailings at the end of Experiment 1 were characterized through chemical and radionuclide analyses and Scanning Electron Microscope-X-ray Emission and Mossbauer Spectroscopy techniques. This report provides an extensive database of temporal variations in leachate characteristics under both normal and accelerated water application rates. It also presents hypotheses of possible leaching mechanisms in the wastes that could explain the observed data, and conceptual model of tailings leaching processes which integrates the results of all the tailings experiments

  8. Mercury's Dynamic Magnetic Tail

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  9. Theseus Tail Being Unloaded

    Science.gov (United States)

    1996-01-01

    The tail of the Theseus prototype research aircraft is seen here being unloaded at NASA's Dryden Flight Research Center, Edwards, California, in May of 1996. The Theseus aircraft, built and operated by Aurora Flight Sciences Corporation, Manassas, Virginia, was a unique aircraft flown at NASA's Dryden Flight Research Center, Edwards, California, under a cooperative agreement between NASA and Aurora. Dryden hosted the Theseus program, providing hangar space and range safety for flight testing. Aurora Flight Sciences was responsible for the actual flight testing, vehicle flight safety, and operation of the aircraft. The Theseus remotely piloted aircraft flew its maiden flight on May 24, 1996, at Dryden. During its sixth flight on November 12, 1996, Theseus experienced an in-flight structural failure that resulted in the loss of the aircraft. As of the beginning of the year 2000, Aurora had not rebuilt the aircraft. Theseus was built for NASA under an innovative, $4.9 million fixed-price contract by Aurora Flight Sciences Corporation and its partners, West Virginia University, Morgantown, West Virginia, and Fairmont State College, Fairmont, West Virginia. The twin-engine, unpiloted vehicle had a 140-foot wingspan, and was constructed largely of composite materials. Powered by two 80-horsepower, turbocharged piston engines that drove twin 9-foot-diameter propellers, Theseus was designed to fly autonomously at high altitudes, with takeoff and landing under the active control of a ground-based pilot in a ground control station 'cockpit.' With the potential ability to carry 700 pounds of science instruments to altitudes above 60,000 feet for durations of greater than 24 hours, Theseus was intended to support research in areas such as stratospheric ozone depletion and the atmospheric effects of future high-speed civil transport aircraft engines. Instruments carried aboard Theseus also would be able to validate satellite-based global environmental change measurements

  10. Rehabilitation of uranium tailings impoundments

    International Nuclear Information System (INIS)

    Crawley, A.H.

    1983-01-01

    Under Australian environmental controls relating to the management of uranium tailings, it is no longer acceptable practice to search for a rehabilitation strategy at the end of production when the generation of tailings has ceased. The uranium projects currently in production and those being proposed are tightly regulated by the authorities. The waste management plans must consider site specific factors and must include selection of appropriate disposal sites and design for long term containment. The final encapsulation in engineered facilities must take into account the probable routes to the environment of the tailings. Rehabilitation shoud be undertaken by the mining and milling operators to standards approved by appropriate authorities. Appropriate administrative arrangements are required, by way of technical committees and financial bonds to ensure that agreed standards of rehabilitation may be achieved. Past and present experience with the rehabilitation of uranium tailings impoundments in Australia is discussed

  11. Sub-aerial tailings deposition

    International Nuclear Information System (INIS)

    Knight, R.B.; Haile, J.P.

    1984-01-01

    The sub-aerial technique involves the systematic deposition of tailings in thin layers and allowing each layer to settle, drain and partially air dry prior to covering with a further layer. Underdrainage produces densities in excess of those achieved by sub-aqueous deposition and any air-drying serves to preconsolidate each layer with a resulting further increase in density. The low permeability of the tailings surface resulting from this deposition technique results in high runoff coefficients and, by decanting the runoff component of direct precipitation, a net evaporation condition can be achieved even in high rainfall areas. An underdrainage system prevents the build-up of excess pore-pressures within the tailings mass and at decommissioning the tailings are fully consolidated and drained thereby eliminating the possibility of any long term seepage. This paper presents a general description of these design concepts, and details of two projects where the concepts have been applied

  12. Sirenomelia apus with vestigial tail.

    Science.gov (United States)

    Parikh, Tushar B; Nanavati, Ruchi N; Udani, Rekha H

    2005-04-01

    Sirenomelia is an exceptionally rare congenital malformation characterized by complete or near complete fusion of lower limbs. A newborn with clinical features of sirenomelia including fused lower limbs in medial position, absent fibula, anal atresia, complete absence of urogenital system (bilateral renal agenesis, absent ureters, urinary bladder, absent internal and external genitalia), a single umbilical artery and a vestigial tail is reported. Association of vestigial tail with sirenomelia is not described in the literature.

  13. Multichannel thickener of flotation tailings

    Energy Technology Data Exchange (ETDEWEB)

    Kondratenko, A F; Shuliko, A N; Zinchenko, A F

    1983-04-01

    A multichannel thickener of flotation tailings developed by Ukrniiugleobogashchenie is described. Tailings with solid content ranging from 40 to 60 g/l are mixed with flocculation reagents (quantity ratio from 60 to 70 g/l) in a turbulent mixer: waste water with tailings fed to the mixer is divided into three streams, flocculation reagents are batched in stages with each water stream. After turbulent mixing, water, tailings and reagent are fed to the settling chamber. Settling chamber (dimensions 2.4 x 1.5 x 1.0 m) is divided into a number of channels by settling surfaces of 0.35 m/sup 2/ each, inclined at an angle of 55 degrees. Distance between the surfaces is 50 mm. The thickener has a total settling surface of 18.7 m/sup 2/. Water with tailings flows upwards, cleaned water is removed by a separating system and settled tailings move downward and accumulate in the compacting chamber (dimensions 1.5 x 1.5 x 0.9 m). From the compacting chamber thickened slurry with solid content from 90 to 150 g/l is removed by a hydraulic system. During performance testing in some plants preparing coal difficult to wash, thickening efficiency amounted to 100%. The results of performance testing are shown in two tables. Factors which influence thickener productivity are evaluated. (In Russian)

  14. Presentations of the CONRAD tailings seminar : exploring the past, present and future of tailings technologies

    International Nuclear Information System (INIS)

    2004-01-01

    This symposium explored oil sand tailings activities in Canada and their associated technologies. It was attended by active and prospective tailings researchers and developers of tailings technology who addressed timely issues regarding mature fine tailings, consolidated tailings, thickened tailings, and emerging tailings technologies. The collaborative research projects that are underway at the Oil Sands Tailings Research Facility were also discussed along with other topics such as tailings ponds management, water treatment, water quality and water supply security. All 16 presentations featured at this conference were indexed separately for inclusion in this database

  15. More tail lesions among undocked than tail docked pigs in a conventional herd

    DEFF Research Database (Denmark)

    Lahrmann, H. P.; Busch, M. E.; D'Eath, R. B.

    2017-01-01

    The vast majority of piglets reared in the European Union (EU) and worldwide is tail docked to reduce the risk of being tail bitten, even though EU animal welfare legislation bans routine tail docking. Many conventional herds experience low levels of tail biting among tail docked pigs, however...

  16. Dewatering tailings impoundments : interior drains

    International Nuclear Information System (INIS)

    Charlie, W.A.; Doehring, D.O.; Durnford, D.S.

    1984-01-01

    For the design of a new uranium tailings impoundment in the western United States, it was proposed that an interior drainage system be considered to economically and reliably minimize potential short- and long-term environmental impacts. The objectives were to decrease the effective hydraulic head on the clay liner, to dewater and stabilize the tailings, and to increase the amount of water recycled to the mill. In addition, desaturation of the impoundment would induce capillary pressure (negative porewater pressure), further reducing the potential movement of dissolved pollutants. This paper presents saturated and unsaturated seepage principles and reviews the concept, criteria and design of the various interior drainage systems considered

  17. Chlorophyll a with a farnesyl tail in thermophilic cyanobacteria.

    Science.gov (United States)

    Wiwczar, Jessica M; LaFountain, Amy M; Wang, Jimin; Frank, Harry A; Brudvig, Gary W

    2017-11-01

    Photosystem II (PSII) of oxygenic photosynthetic organisms normally contains exclusively chlorophyll a (Chl a) as its major light-harvesting pigment. Chl a canonically consists of the chlorin headgroup with a 20-carbon, 4-isoprene unit, phytyl tail. We have examined the 1.9 Å crystal structure of PSII from thermophilic cyanobacteria reported by Shen and coworkers in 2012 (PDB accession of 3ARC/3WU2). A newly refined electron density map from this structure, presented here, reveals that some assignments of the cofactors may be different from those modeled in the 3ARC/3WU2 structure, including a specific Chl a that appears to have a truncated tail by one isoprene unit. We provide experimental evidence using high-performance liquid chromatography and mass spectrometry for a small population of Chl a esterified to a 15-carbon farnesyl tail in PSII of thermophilic cyanobacteria.

  18. Predicting radon flux from uranium mill tailings

    International Nuclear Information System (INIS)

    Freeman, H.D.; Hartley, J.N.

    1983-11-01

    Pacific Northwest Laboratory (PNL), under contract to the US Department of Energy (DOE) Uranium Mill Tailings Remedial Action Project (UMTRAP) office, is developing technology for the design of radon barriers for uranium mill tailings piles. To properly design a radon cover for a particular tailings pile, the radon flux emanating from the bare tailings must be known. The tailings characteristics required to calculate the radon flux include radium-226 content, emanating power, bulk density, and radon diffusivity. This paper presents theoretical and practical aspects of estimating the radon flux from an uranium tailings pile. Results of field measurements to verify the calculation methodology are also discussed. 24 references, 4 figures, 4 tables

  19. Ruin problems and tail asymptotics

    DEFF Research Database (Denmark)

    Rønn-Nielsen, Anders

    The thesis Ruin Problems and Tail Asymptotics provides results on ruin problems for several classes of Markov processes. For a class of diffusion processes with jumps an explicit expression for the joint Laplace transform of the first passage time and the corresponding undershoot is derived...

  20. Liner used in tailings ponds

    International Nuclear Information System (INIS)

    Dinchak, W.G.

    1984-01-01

    A composite liner has been developed for use in hazardous waste impoundments and in tailings ponds where uranium is involved. The liner offers a high degree of reliability against seepage, is durable, and provides a firm working surface. The advantages of the liner are discussed

  1. Portfolio selection with heavy tails

    NARCIS (Netherlands)

    Hyung, N.; Vries, de C.G.

    2007-01-01

    Consider the portfolio problem of choosing the mix between stocks and bonds under a downside risk constraint. Typically stock returns exhibit fatter tails than bonds corresponding to their greater downside risk. Downside risk criteria like the safety first criterion therefore often select corner

  2. Portfolio Selection with Heavy Tails

    NARCIS (Netherlands)

    N. Hyung (Namwon); C.G. de Vries (Casper)

    2004-01-01

    textabstractConsider the portfolio problem of choosing the mix between stocks and bonds under a downside risk constraint. Typically stock returns exhibit fatter tails than bonds corresponding to their greater downside risk. Downside risk criteria like the safety first criterion therefore of ten

  3. Tails, Fears and Risk Premia

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Victor

    solely be explained by the level of the volatil- ity. Our empirical investigations are essentially model-free. We estimate the expected values of the tails under the statistical probability measure from "medium" size jumps in high-frequency intraday prices and an extreme value theory approximation...

  4. Capital regulation and tail risk

    NARCIS (Netherlands)

    Perotti, E.; Ratnovski, L.; Vlahu, R.

    2011-01-01

    The paper studies risk mitigation associated with capital regulation, in a context when banks may choose tail risk assets. We show that this undermines the traditional result that higher capital reduces excess risk-taking driven by limited liability. When capital raising is costly, poorly

  5. Capital regulation and tail risk

    NARCIS (Netherlands)

    Perotti, E.; Ratnovski, L.; Vlahu, R.

    2011-01-01

    The paper studies risk mitigation associated with capital regulation, in a context where banks may choose tail risk assets. We show that this undermines the traditional result that higher capital reduces excess risk taking driven by limited liability. Moreover, higher capital may have an unintended

  6. DLM for T-Tails

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2007-06-01

    Full Text Available This paper describes the extension of the DLM to account for effects that are critical to the modelling of T-tail flutter. The boundary condition is made more general to account for yaw/dihedral and sideslip/dihedral coupling and the calculation...

  7. UTAP, U Tailings Assessment Program

    International Nuclear Information System (INIS)

    Holmes, Ron

    1998-01-01

    1 - Description of program or function: UTAP carries out probabilistic analyses of the behaviour and environmental effects of uranium mill tailings, following close-out of milling operations. The models have been designed to allow predictions to be made for distances up to 50 kilometers in all directions from the tailings area. The models include features which include the ability to incorporate different receptors and site characteristics and to deal with input parameters which vary with time. 2 - Method of solution: UTAP is composed of a number of modules. These may be classified as either component or control modules. Component modules (or models) are the programs directly concerned with the simulation of a uranium tailings physical system; that is the computer implementation of the mathematical models representing the uranium tailings pile and surrounding environment. Control modules provide the infrastructure for probabilistic analysis using the component modules. These functions include probabilistic sampling of input parameters such as constant, normal, log-normal, uniform, log-uniform, triangular, Weibull, Beta, arbitrary and correlated. The sampling method used is straight Monte Carlo. The radionuclides modelled are: natural uranium, total thorium, radium-226, radon-222 and lead-210. The pH of the reference uranium tailings site and a chained river-lake system are also modelled. For the afore- mentioned radionuclides the following pathways of dose to the receptors modelled: water consumption, fish consumption, radon inhalation, dust inhalation, vegetable consumption, animal produce consumption and ground-shine. 3 - Restrictions on the complexity of the problem: The maximum number of steps through time allowed is 300

  8. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  9. Segregation and differential settling in flocculated tailings

    Energy Technology Data Exchange (ETDEWEB)

    Farinato, R.S.; Mahmoudkhani, A.; Fenderson, T.; Watson, P. [Kemira, Atlanta, GA (United States)

    2010-07-01

    Untreated oil sands tailings have a high solids content, have poor dewaterability, and contain no aggregates. This PowerPoint presentation investigated segregation and differential settling in flocculated tailings. Tailings were treated with gypsum and various polymers. Cylinder settling, dynamic rheometry, particle size analysis, and microscopy techniques were used to characterize the composite tailings. The particles sizes of the samples were evaluated in relation to shear rate, bed depth, and treatment. The study showed that the gypsum-treated tailings had small aggregates, size stratification, a high solids content, and poor dewaterability. The polymer N-treated tailings had the lowest solids content, good dewaterability, and weak aggregates. The polymer A-treated tailings had a low solids content, very good dewaterability, and strong aggregates. The addition of a coagulant to the polymer-A treated tailings provided weaker aggregates and a higher solids content. tabs., figs.

  10. Health risks from uranium mill tailings

    International Nuclear Information System (INIS)

    Russell, J.L.

    1992-01-01

    This paper reviews the risk to public health and the environment from uranium mill tailings. The steps taken by the Environmental Protection Agency (EPA) to reduce this risk from tailing are summarized

  11. Enhancement Experiment on Cementitious Activity of Copper-Mine Tailings in a Geopolymer System

    Directory of Open Access Journals (Sweden)

    Lin Yu

    2017-12-01

    Full Text Available Copper-mine tailings are the residual products after the extraction of precious copper metal from copper ores, and their storage can create numerous environmental problems. Many researchers have used copper-mine tailings for the preparation of geopolymers. This paper studies the enhancement of the cementitious activity of copper-mine tailings in geopolymer systems. First, copper-mine tailings are activated through mechanical grinding activation. Then, the mechanically activated copper-mine tailings are further processed through thermal activation and alkaline-roasting activation. The cementitious activity index of copper-mine tailings is characterized through the degree of leaching concentration of Si and Al. It was observed that the Si and Al leaching concentration of mechanically activated tailings was increased by 26.03% and 93.33%, respectively. The concentration of Si and Al was increased by 54.19% and 119.92%, respectively. For alkaline-roasting activation, roasting time, temperature and the mass ratio of copper-mine tailings to NaOH (C/N ratio were evaluated through orthogonal tests, and the best condition for activation was 120 min at 600 °C with a C/N ratio of 5:1. In this study, scanning electron microscopy (SEM, X-ray diffraction (XRD and infra-red (IR analysis show that mechanical, thermal and alkaline-roasting activation could be used to improve the cementitious activity index of copper-mine tailings.

  12. Risk assessment of tailings facility dam failure

    OpenAIRE

    Hadzi-Nikolova, Marija; Mirakovski, Dejan; Stefanova, Violeta

    2011-01-01

    This paper presents the consequences of tailings facility dam failure and therefore the needs for its risk assessment. Tailings are fine-grained wastes of the mining industry, output as slurries, due to mixing with water during mineral processing. Tailings dams vary a lot as it is affected by: tailings characteristics and mill output, site characteristics as: topography, hydrology, geology, groundwater, seismicity and available material and disposal methods. The talings which accumulat...

  13. Cylinder Symmetric Measures with the Tail Property

    NARCIS (Netherlands)

    Balkema, A.A.

    2006-01-01

    Abstract: A Pareto distribution has the property that any tail of the distribution has the same shape as the original distribution. The exponential distribution and the uniform distribution have the tail property too. The tail property characterizes the univariate generalized Pareto distributions.

  14. Plasma currents and anisotropy in the tail-dipole transition region

    Science.gov (United States)

    Artemyev, A.; Zhang, X. J.; Angelopoulos, V.; Runov, A.

    2017-12-01

    Using conjugated THEMIS and Van Allen Probes observations in the nightside magnetosphere, we examine statistically plasma and magnetic field characteristics at multiple locations simultaneously across the 3-10 RE region (i.e., across the tail-dipole transition region, whose location depends on tail flux loading and the strength of global convection). We find that the spatial distributions of ion and electron anisotropies vary significantly but systematically with radial distance and geomagnetic activity. For low Kp (4), the anisotropy profiles for ions and electrons reverse: ions are isotropic closer to the Earth and field-aligned in the tail, whereas electrons are transversely anisotropic closer to Earth but isotropic in the tail. Using the measured plasma anisotropy radial profiles we estimate the currents from curvature drifts and compare them with diamagnetic currents. We also discuss the implications of the observed plasma anisotropies for the presence and spatial distribution of field-aligned electric fields.

  15. Numerical modelling for stability of tailings dams

    OpenAIRE

    Auchar, Muhammad; Mattsson, Hans; Knutsson, Sven

    2013-01-01

    A tailings dam is a large embankment structure that is constructed to store the waste from the mining industry. Stability problems may occur in a tailings dam due to factors such as quick rate of raising, internal erosion and liquefaction. The failure of a tailings dam may cause loss of human life and environmental degradation. Tailings Dams must not only be stable during the time the tailings storage facility is in operation, but also long time after the mine is closed. In Sweden, the licens...

  16. Thermal stabilization of uranium mill tailings

    International Nuclear Information System (INIS)

    Dreesen, D.R.; Williams, J.M.; Cokal, E.J.

    1981-01-01

    The sintering of tailings at high temperatures (1200 0 C) has shown promise as a conditioning approach that greatly reduces the 222 Rn emanation of uranium mill tailings. The structure of thermally stabilized tailings has been appreciably altered producing a material that will have minimal management requirements and will be applicable to on-site processing and disposal. The mineralogy of untreated tailings is presented to define the structure of the original materials. Quartz predominates in most tailings samples; however, appreciable quantities of gypsum, clay, illite, or albites are found in some tailings. Samples from the Durango and Shiprock sites have plagioclase-type aluminosilicates and non-aluminum silicates as major components. The iron-rich vanadium tailings from the Salt Lake City site contain appreciable quantities of α-hematite and chloroapatite. The reduction in radon emanation power and changes in mineralogy as a function of sintering temperature are presented

  17. Ecotoxicity of Mine Tailings: Unrehabilitated Versus Rehabilitated.

    Science.gov (United States)

    Maboeta, M S; Oladipo, O G; Botha, S M

    2018-05-01

    Earthworms are bioindicators of soil pollution. The ecotoxicity of tailings from selected gold mines in South Africa was investigated utilizing Eisenia andrei bioassays and biomarkers. Samples were obtained from unrehabilitated, rehabilitated and naturally vegetated sites. Biomass, neutral red retention time (NRRT), survival and reproduction were assessed using standardized protocols. Earthworm biomass, NRRT and reproductive success in rehabilitated tailings (comparable to naturally vegetated site) were significantly higher (p tailings. In addition, significantly lower (p tailings compared to the unrehabilitated. Further, significantly lower (p tailings than the rehabilitated and naturally vegetated sites. Overall, reduced ecotoxicity effects were confirmed in rehabilitated compared to unrehabilitated tailings. This suggests that rehabilitation as a post-mining restorative strategy has strong positive influence on mine tailings.

  18. Mineralogy and geochemistry of uranium mill tailings

    International Nuclear Information System (INIS)

    Pagel, M.; Somot, S.

    2002-01-01

    We have investigated three main types of uranium mill tailings: (1) acid mill tailings (Mounana, Gabon), (2) neutralized acid mill tailings (Ecarpiere and Jouac, France) and (3) alkaline mill tailings (Lodeve, France). We have focused especially on radium behaviour which is of major environmental concern in these tailings, but other metals were also studied. It is shown that in type 1 , trapping of 226 Ra by anglesite and barite is dominant whereas in types 2 and 3, 226 Ra is mainly or significantly scavenged by Fe- Mn oxyhydroxides. This study points out the importance of keeping conditions in which these oxyhydroxides will be stable for the long-term. Uranium would be also released during acidification of the tailings. This shows the importance to know more about the behavior of Ra during the crystallization of oxyhydroxides and during tailings diagenesis. Therefore, it is very important to study the sorption of Ra by clay minerals or late authigeneous minerals such as barite. (author)

  19. Which is the most preventive measure against tail damage in finisher pigs: tail docking, straw provision or lowered stocking density?

    DEFF Research Database (Denmark)

    Larsen, Mona Lilian Vestbjerg; Andersen, Heidi Mai-Lis; Pedersen, Lene Juul

    2018-01-01

    One challenge of intensive pig production is tail damage caused by tail biting, and farmers often decrease the prevalence of tail damage through tail docking. However, tail docking is not an optimal preventive measure against tail damage and thus, it would be preferable to replace it. The aim of ...

  20. Uranium mill tailings neutralization: contaminant complexation and tailings leaching studies

    International Nuclear Information System (INIS)

    Opitz, B.E.; Dodson, M.E.; Serne, R.J.

    1985-05-01

    Laboratory experiments were performed to compare the effectiveness of limestone (CaCO 3 ) and hydrated lime [Ca(OH) 2 ] for improving waste water quality through the neutralization of acidic uranium mill tailings liquor. The experiments were designed to also assess the effects of three proposed mechanisms - carbonate complexation, elevated pH, and colloidal particle adsorption - on the solubility of toxic contaminants found in a typical uranium mill waste solution. Of special interest were the effects each of these possible mechanisms had on the solution concentrations of trace metals such as Cd, Co, Mo, Zn, and U after neutralization. Results indicated that the neutralization of acidic tailings to a pH of 7.3 using hydrated lime provided the highest overall waste water quality. Both the presence of a carbonate source or elevating solution pH beyond pH = 7.3 resulted in a lowering of previously achieved water quality, while adsorption of contaminants onto colloidal particles was not found to affect the solution concentration of any constituent investigated. 24 refs., 8 figs., 19 tabs

  1. Radon emanation characteristics of uranium mill tailings

    International Nuclear Information System (INIS)

    Nielson, K.K.; Freeman, H.D.; Hartley, J.N.; Mauch, M.L.; Rogers, V.C.

    1982-01-01

    Radon emanation from uranium mill tailings was examined with respect to the mechanisms of emanation and the physical properties of the tailings which affect emanation. Radon emanation coefficients were measured at ambient moisture on 135 samples from the 1981 field test site at the Grand Junction tailings pile. These coefficients showed a similar trend with moisture to those observed previously with uranium ores, and averaged 0.10 + or - 0.02 at dryness and 0.38 + or - 0.04 for all samples having greater than five weight-percent moisture. Small differences were noted between the maximum values of the coefficients for the sand and slime fractions of the tailings. Separate measurements on tailings from the Vitro tailings pile exhibited much lower emanation coefficients for moist samples, and similar coefficients for dry samples. Alternative emanation measurement techniques were examined and procedures are recommended for use in future work

  2. Molecular ions in comet tails

    International Nuclear Information System (INIS)

    Wyckoff, S.; Wehinger, P.A.

    1976-01-01

    Band intensities of the molecular ions CH + , CO + , N 2 + , and H 2 O + have been determined on an absolute scale from tail spectra of comet Kohoutek (1973f) and comet Bradfield (1974b). Photoionization and photodissociation rates have been computed for CH, CO, and N 2 . Also emission rate excitation g-factors for (1) photoionization plus excitation and (2) resonance fluorescence have been computed for the observed ions. It is shown that resonance fluorescence is the dominant excitation mechanism for observed comet tail ions at rapprox. =1 AU. Band system luminosities and molecular ion abundances within a projected nuclear distance rho 4 km have been determined for CH + , CO + , N 2 + , and H 2 O + in comet Kohoutek, and for H 2 O + in comet Bradfield. Estimates are also given for column densities of all observed ions at rhoapprox. =10 4 km on the tailward side of the coma. The observed H 2 O + column densities were found to be roughly the same in comet Kohoutek and comet Bradfield et equal heliocentric distances, while CO + was found to be approximately 100 times more abundant than H 2 O + , N 2 + , and CH + at rhoapprox. =10 4 km in comet Kohoutek. Finally, the relative abundances of the observed ions and of the presumed parent neutral species are briefly discussed

  3. Oil sands tailings management project

    Energy Technology Data Exchange (ETDEWEB)

    Godwalt, C. [Alberta WaterSMART, Calgary, AB (Canada); Kotecha, P. [Suncor Energy Inc, Calgary, AB (Canada); Aumann, C. [Alberta Innovates - Technology Futures, Alberta Governement, AB (Canada)

    2010-11-15

    The Oil sands leadership initiative (OSLI) works with the Government of Alberta on the development of the oil sands industry, considering environmental, economical and social aspects. Water management was identified as one of most important areas to focus on. Alberta WaterSMART was requested to support the development and the management of projects resulting from the work done or underway in this field. The development of a regional water management solution stood out as the most interesting solution to obtain significant results. In the Athabasca Region, oil sands producers work independently on their water sourcing and disposal with particular attention to fresh water conservation and economics. The Athabasca River represents a source for mines and distant saline aquifers are the target of steam assisted gravity drainage (SAGD) operators. As part of a four-phase project aiming to study the environmental and economic footprint (EEF) benefit of alternatives for Athabasca oil sands production water supply and disposal, the purpose of the tailings water management project was to identify tailings treatment technologies that are ready to be implemented, and to design and evaluate solutions in order to improve regional oil sands production water sourcing and disposal. Alternatives were evaluated based on their total EEF, applying a lifecycle assessment methodology with a particular attention on the quantification of important performance indicators. 25 refs., 8 tabs., 40 figs.

  4. Oil sands tailings management project

    International Nuclear Information System (INIS)

    Godwalt, C.; Kotecha, P.; Aumann, C.

    2010-11-01

    The Oil sands leadership initiative (OSLI) works with the Government of Alberta on the development of the oil sands industry, considering environmental, economical and social aspects. Water management was identified as one of most important areas to focus on. Alberta WaterSMART was requested to support the development and the management of projects resulting from the work done or underway in this field. The development of a regional water management solution stood out as the most interesting solution to obtain significant results. In the Athabasca Region, oil sands producers work independently on their water sourcing and disposal with particular attention to fresh water conservation and economics. The Athabasca River represents a source for mines and distant saline aquifers are the target of steam assisted gravity drainage (SAGD) operators. As part of a four-phase project aiming to study the environmental and economic footprint (EEF) benefit of alternatives for Athabasca oil sands production water supply and disposal, the purpose of the tailings water management project was to identify tailings treatment technologies that are ready to be implemented, and to design and evaluate solutions in order to improve regional oil sands production water sourcing and disposal. Alternatives were evaluated based on their total EEF, applying a lifecycle assessment methodology with a particular attention on the quantification of important performance indicators. 25 refs., 8 tabs., 40 figs.

  5. Tail anisotropy instability during plasma current rise by lower-hybrid waves in a tokamak

    International Nuclear Information System (INIS)

    Yamagiwa, Mitsuru.

    1986-01-01

    Tail anisotropy instability during lower-hybrid current rise is investigated. Tail formation by lower-hybrid waves is studied by using a Fokker-Planck equation combined with the return field and the rf associated terms. Quasi-linear relaxation of the electron tail distribution under the influence of the plasma waves excited due to the instability is examined. It is found that the instability condition is related to the strength of the parallel diffusion by lower-hybrid waves and the ratio of the electron cyclotron frequency to the electron plasma frequency. The time scale between the instability spikes and the suppression of the instability by electron cyclotron heating are also discussed. (author)

  6. Assessing Risks of Mine Tailing Dam Failures

    Science.gov (United States)

    Concha Larrauri, P.; Lall, U.

    2017-12-01

    The consequences of tailings dam failures can be catastrophic for communities and ecosystems in the vicinity of the dams. The failure of the Fundão tailings dam at the Samarco mine in 2015 killed 19 people with severe consequences for the environment. The financial and legal consequences of a tailings dam failure can also be significant for the mining companies. For the Fundão tailings dam, the company had to pay 6 billion dollars in fines and twenty-one executives were charged with qualified murder. There are tenths of thousands of active, inactive, and abandoned tailings dams in the world and there is a need to better understand the hazards posed by these structures to downstream populations and ecosystems. A challenge to assess the risks of tailings dams in a large scale is that many of them are not registered in publicly available databases and there is little information about their current physical state. Additionally, hazard classifications of tailings dams - common in many countries- tend to be subjective, include vague parameter definitions, and are not always updated over time. Here we present a simple methodology to assess and rank the exposure to tailings dams using ArcGIS that removes subjective interpretations. The method uses basic information such as current dam height, storage volume, topography, population, land use, and hydrological data. A hazard rating risk was developed to compare the potential extent of the damage across dams. This assessment provides a general overview of what in the vicinity of the tailings dams could be affected in case of a failure and a way to rank tailings dams that is directly linked to the exposure at any given time. One hundred tailings dams in Minas Gerais, Brazil were used for the test case. This ranking approach could inform the risk management strategy of the tailings dams within a company, and when disclosed, it could enable shareholders and the communities to make decisions on the risks they are taking.

  7. Average configuration of the geomagnetic tail

    International Nuclear Information System (INIS)

    Fairfield, D.H.

    1979-01-01

    Over 3000 hours of Imp 6 magnetic field data obtained between 20 and 33 R/sub E/ in the geomagnetic tail have been used in a statistical study of the tail configuration. A distribution of 2.5-min averages of B/sub z/ as a function of position across the tail reveals that more flux crosses the equatorial plane near the dawn and dusk flanks (B-bar/sub z/=3.γ) than near midnight (B-bar/sub z/=1.8γ). The tail field projected in the solar magnetospheric equatorial plane deviates from the x axis due to flaring and solar wind aberration by an angle α=-0.9 Y/sub SM/-2.7, where Y/sub SM/ is in earth radii and α is in degrees. After removing these effects, the B/sub y/ component of the tail field is found to depend on interplanetary sector structure. During an 'away' sector the B/sub y/ component of the tail field is on average 0.5γ greater than that during a 'toward' sector, a result that is true in both tail lobes and is independent of location across the tail. This effect means the average field reversal between northern and southern lobes of the tail is more often 178 0 rather than the 180 0 that is generally supposed

  8. Unique structural features facilitate lizard tail autotomy.

    Science.gov (United States)

    Sanggaard, Kristian W; Danielsen, Carl Chr; Wogensen, Lise; Vinding, Mads S; Rydtoft, Louise M; Mortensen, Martin B; Karring, Henrik; Nielsen, Niels Chr; Wang, Tobias; Thøgersen, Ida B; Enghild, Jan J

    2012-01-01

    Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed that tail shedding by the Tokay gecko (Gekko gecko) and the associated extracellular matrix (ECM) rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail of Gekko gecko was pre-severed at distinct sites and that its structural integrity depended on the adhesion between these segments.

  9. Unique structural features facilitate lizard tail autotomy

    DEFF Research Database (Denmark)

    Sanggaard, Kristian W; Danielsen, Carl Chr; Wogensen, Lise

    2012-01-01

    Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed...... that tail shedding by the Tokay gecko (Gekko gecko) and the associated extracellular matrix (ECM) rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail...

  10. Lateral movements of a massive tail influence gecko locomotion: an integrative study comparing tail restriction and autotomy

    OpenAIRE

    Jagnandan, Kevin; Higham, Timothy E.

    2017-01-01

    Tails are an intricate component of the locomotor system for many vertebrates. Leopard geckos (Eublepharis macularius) possess a large tail that is laterally undulated during steady locomotion. However, the tail is readily shed via autotomy, resulting in the loss of tail function, loss in body mass, and a cranial shift in the center of mass. To elucidate the function of tail undulations, we investigated changes in limb kinematics after manipulating the tail artificially by restricting tail un...

  11. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    Directory of Open Access Journals (Sweden)

    Bin Han

    2016-01-01

    Full Text Available A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 days are 58%–77%, 50%–60%, and 28%–51%, respectively, which are higher than those of flotation tailings. Slurry fluidity of neutralized tailings is lower than that of flotation tailings, while, in these two tailings, the difference of slump and diffusivity values is less than 6%, which is not a significant difference in slurry fluidity. The reason for neutralized tailings showing higher UCS is as follows: during backfill curing, neutralization tailings produce abundant crystals of CaSO4·2H2O in interlaced structure which helps in combining aggregates closely; CaSO4·2H2O hydrates with C3A C4AF contained in the cement and forms clavate cement bacillus which works as a micro reinforcing steel bar. The test proved that neutralized tailings are more optimal for backfilling.

  12. Characterization and dewatering of flotation technological tailings

    Directory of Open Access Journals (Sweden)

    Grigorova I.

    2014-01-01

    Full Text Available The treatment of flotation tailings is today a subject of interest in mineral processing because of the potential of wasted materials as an actual mineral resource and because of environmental reasons. Decantation ponds are found at almost every mine in the world. They are large earth fill dams containing the residue of the milling process to extract metals from mined ores. Traditional wet tailings disposal has been problematic due to the risk of ground water contamination and the difficulty in rehabilitating storage sites. Tailings dams are at risk of failure due to leakage, instability, liquefaction, and poor design. In the last few years the use of paste technology in the disposal of mine tailings is increasingly studied as an option to conventional tailings dams. The Lucky Invest Concentrator is located in the Eastern Rhodopes Mountain of Bulgaria. Since 1959 lead-zinc ores are dressed. Finally, during the flotation cycle lead and zinc concentrates are produced. The final technological processing waste precipitates in tailing pond. Research and development program has started to established opportunities to obtain dry deposit of the ore processing residue and analyses the feature of new tailing disposal method. The tailings particle size distributions and chemical compositions were determined. The data from laboratory and pilot scale tests clearly illustrate that there are the possibilities to obtaine lead-zinc dewatered tailings. The experimental results show that new cyclone modifications have a potential in dewatering technology of flotation tailings. It appears that dewatering cyclones can be an approach on new tailings pond elimination technology.

  13. Mineralogical characterization of arsenic, iron, and nickel in uranium mine tailings using XAS and EMPA

    International Nuclear Information System (INIS)

    Essilfie-Dughan, J.; Hendry, M.J.; Warner, J.; Kotzer, T.

    2010-01-01

    In northern Saskatchewan, Canada, high-grade uranium ores and the resulting tailings can contain high levels of arsenic (As), iron (Fe), and nickel (Ni). An environmental concern in the uranium mining industry is the long-term stabilization of these elements of concern (EOCs) within tailings management facilities thereby mitigating their transfer to the surrounding groundwater. Characterization of these As-, Fe- and Ni-bearing minerals and complexes must be carried out to evaluate their solubility and long-term stability within the tailings mass. Synchrotron-based bulk x-ray absorption spectroscopy (XAS) has been used to study the speciation of these EOCs in mine tailing samples obtained from the Deilmann Tailings Management Facility (DTMF) at Key Lake, Saskatchewan. Electron microprobe analysis (EMPA) and synchrotron-based micro-focussing x-ray fluorescence mapping and absorption spectroscopy (μXRF; μXAS ) have also been employed to study spatial distribution and speciation at the micron scale. Comparisons of K-edge absorption spectra of tailings samples and reference compounds indicate the dominant oxidation states of As, Fe, and Ni in the mine tailings samples are +5, +3, and +2, respectively, largely reflecting their deposition in an oxidized environment and complexation within stable oxic phases. Backscattered electron (BSE) images of the tailings from the electron microprobe indicate the presence of gypsum/lime nodules surrounded by metallic rims mainly consisting of As, Fe, and Ni. μXRF elemental mapping confirms these EPMA results. μXAS collected within the metal-bearing rims indicates As and Fe is present mainly in the +5 and +3 oxidation state, respectively. (author)

  14. Making the long tail work

    DEFF Research Database (Denmark)

    Thuesen, Christian Langhoff; Jensen, Jens Stissing; Gottlieb, Stefan Christoffer

    2009-01-01

    The paper discusses the development and impact of construction research the past 25 years. Theoretically, the paper builds on two fundamental insights: The Pareto principle (the 80-20 rule) and the Thomas theorem: "If men define situations as real, they are real in their consequences" (Thomas......’s predominant view of buildings – as unique – implies that: 1) the nature of the construction processes is chaotic, 2) the buildings are realised through onsite project work rather than through offsite production; and 3) project management is the fundamental management principle. The paper further identifies...... how attempts to develop new construction practices like partnering and lean implicitly reproduce this myth. The result is that construction research the past 25 years has been constructing the long tail in a way that hinders radical development of the construction industry. The paper concludes...

  15. Profitable tail-end production

    Energy Technology Data Exchange (ETDEWEB)

    Pinchbeck, R.H.

    1997-12-31

    This presentation discusses the origins of the present challenge faced in making mature oil fields profitable in the North Sea. It briefly examines the origins of these challenges, which are rooted in the industrial psychology of the North Sea. It develops a methodological formula for the successful re-engineering of inefficiently-run assets, focusing in particular on the personnel management aspects. It identifies some key areas to seek sustainable cost reductions and recognises the importance of renewing the context for investment in tail-end fields. Finally, it speculates about the way in which the learnings developed in the experiences of the last few years will influence the future of the North Sea. 2 refs.

  16. Research on uranium tailings disposal technology at CANMET, Ottawa

    International Nuclear Information System (INIS)

    Skeaff, J.M.; Ritcey, G.M.; Jongejan, A.; Silver, M.

    1982-01-01

    In this paper, results from three continuing investigations at CANMET on uranium tailings management are presented. These investigations are: cleaning of tailings by flotation, conversion of municipal wastes into compost for use as topsoil on uranium tailings, methods for the chemical fixation of uranium tailings and a laboratory determination of the rate of release of environmental contaminants from uranium tailings

  17. Heavy mineral concentration from oil sand tailings

    Energy Technology Data Exchange (ETDEWEB)

    Chachula, F.; Erasmus, N. [Titanium Corp. Inc., Regina, SK (Canada)

    2008-07-01

    This presentation described a unique technique to recover heavy minerals contained in the froth treatment tailings produced by oil sand mining extraction operations in Fort McMurray, Alberta. In an effort to process waste material into valuable products, Titanium Corporation is developing technology to recover heavy minerals, primarily zircon, and a portion of bitumen contained in the final stage of bitumen processing. The process technology is being developed to apply to all mined oil sands operations in the Fort McMurray region. In 2004, Titanium Corporation commissioned a pilot research facility at the Saskatchewan Research Council to test dry oil sands tailings. In 2005, a bulk sampling pilot plant was connected to the fresh oil sands tailings pipeline on-site in Fort McMurray, where washed sands containing heavy minerals were processed at a pilot facility. The mineral content in both deposited tailings and fresh pipeline tailings was assessed. Analysis of fresh tailings on a daily basis identified a constant proportion of zircon and higher levels of associated bitumen compared with the material in the deposited tailings. The process flow sheet design was then modified to remove bitumen from the heavy minerals and concentrate the minerals. A newly modified flotation process was shown to be a viable processing route to recover the heavy minerals from froth treatment tailings. 8 refs., 9 tabs., 12 figs.

  18. Electrodialytic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, A.; Ottpsen, Lisbeth M.

    2005-01-01

    electrodialytic remediation experiments on copper mine tailings. The results show that electric current could remove copper from watery tailing if the potential gradient was higher than 2V/cm during 21 days. With addition of sulphuric acid, the process was enhanced because the pH decreased to around 4...

  19. Crystal Structure of Bacteriophage SPP1 Distal Tail Protein (gp19.1)

    Science.gov (United States)

    Veesler, David; Robin, Gautier; Lichière, Julie; Auzat, Isabelle; Tavares, Paulo; Bron, Patrick; Campanacci, Valérie; Cambillau, Christian

    2010-01-01

    Siphophage SPP1 infects the Gram-positive bacterium Bacillus subtilis using its long non-contractile tail and tail-tip. Electron microscopy (EM) previously allowed a low resolution assignment of most orf products belonging to these regions. We report here the structure of the SPP1 distal tail protein (Dit, gp19.1). The combination of x-ray crystallography, EM, and light scattering established that Dit is a back-to-back dimer of hexamers. However, Dit fitting in the virion EM maps was only possible with a hexamer located between the tail-tube and the tail-tip. Structure comparison revealed high similarity between Dit and a central component of lactophage baseplates. Sequence similarity search expanded its relatedness to several phage proteins, suggesting that Dit is a docking platform for the tail adsorption apparatus in Siphoviridae infecting Gram-positive bacteria and that its architecture is a paradigm for these hub proteins. Dit structural similarity extends also to non-contractile and contractile phage tail proteins (gpVN and XkdM) as well as to components of the bacterial type 6 secretion system, supporting an evolutionary connection between all these devices. PMID:20843802

  20. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    OpenAIRE

    Han, Bin; Sun, Wei; Yu, Shaofeng; Liu, Chao; Yao, Song; Wu, Jianxun

    2016-01-01

    A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 ...

  1. Monte Carlo-based tail exponent estimator

    Science.gov (United States)

    Barunik, Jozef; Vacha, Lukas

    2010-11-01

    In this paper we propose a new approach to estimation of the tail exponent in financial stock markets. We begin the study with the finite sample behavior of the Hill estimator under α-stable distributions. Using large Monte Carlo simulations, we show that the Hill estimator overestimates the true tail exponent and can hardly be used on samples with small length. Utilizing our results, we introduce a Monte Carlo-based method of estimation for the tail exponent. Our proposed method is not sensitive to the choice of tail size and works well also on small data samples. The new estimator also gives unbiased results with symmetrical confidence intervals. Finally, we demonstrate the power of our estimator on the international world stock market indices. On the two separate periods of 2002-2005 and 2006-2009, we estimate the tail exponent.

  2. Analysis of Heavy-Tailed Time Series

    DEFF Research Database (Denmark)

    Xie, Xiaolei

    This thesis is about analysis of heavy-tailed time series. We discuss tail properties of real-world equity return series and investigate the possibility that a single tail index is shared by all return series of actively traded equities in a market. Conditions for this hypothesis to be true...... are identified. We study the eigenvalues and eigenvectors of sample covariance and sample auto-covariance matrices of multivariate heavy-tailed time series, and particularly for time series with very high dimensions. Asymptotic approximations of the eigenvalues and eigenvectors of such matrices are found...... and expressed in terms of the parameters of the dependence structure, among others. Furthermore, we study an importance sampling method for estimating rare-event probabilities of multivariate heavy-tailed time series generated by matrix recursion. We show that the proposed algorithm is efficient in the sense...

  3. Why are most EU pigs tail docked?

    DEFF Research Database (Denmark)

    D'eath, R.B.; Niemi, J.K.; Vosough Ahmadi, B.

    2016-01-01

    To limit tail biting incidence, most pig producers in Europe tail dock their piglets. This is despite EU Council Directive 2008/120/EC banning routine tail docking and allowing it only as a last resort. The paper aims to understand what it takes to fulfil the intentions of the Directive...... by examining economic results of four management and housing scenarios, and by discussing their consequences for animal welfare in the light of legal and ethical considerations. The four scenarios compared are: ‘Standard Docked’, a conventional housing scenario with tail docking meeting the recommendations...... for Danish production (0.7 m2/pig); ‘Standard Undocked’, which is the same as ‘Standard Docked’ but with no tail docking, ‘Efficient Undocked’ and ‘Enhanced Undocked’, which have increased solid floor area (0.9 and 1.0 m2/pig, respectively) provision of loose manipulable materials (100 and 200 g/straw per...

  4. Uranium mill tailings remedial action technology

    International Nuclear Information System (INIS)

    Hartley, J.N.; Gee, G.W.

    1984-01-01

    The uranium milling process involves the hydrometallurgical extraction of uranium from ores and the resultant generation of large quantities of waste referred to as tailings. Uranium mill tailings have been identified as requiring remediation because they contain residual radioactive material that is not removed in the milling process. Potential radiation exposure can result from direct contact with the tailings, from radon gas emitted by the tailings, and from radioactive contamination of groundwater. As a result, the technology developed under the US Department of Energy (DOE) Uranium Mill Tailings Remedial Action Project (UMTRAP) and the US Nuclear Regulatory Commission (NRC) Uranium Recovery Program have focused on radon control, groundwater contamination and the long-term protection of the containment system. This paper briefly summarizes the UMTRAP and NRC remedial action technology development. 33 references, 9 figures, 5 tables

  5. Tail posture predicts tail biting outbreaks at pen level in weaner pigs

    DEFF Research Database (Denmark)

    Lahrmann, Helle Pelant; Hansen, Christian Fink; D'Eath, Rick

    2018-01-01

    posture and behaviour could be detected at pen level between upcoming tail biting pens (T-pens) and control pens (C-pens). The study included 2301 undocked weaner pigs in 74 pens (mean 31.1 pigs/pen; SD 1.5). Tails were scored three times weekly (wound freshness, wound severity and tail length) between 07......Detecting a tail biting outbreak early is essential to reduce the risk of pigs getting severe tail damage. A few previous studies suggest that tail posture and behavioural differences can predict an upcoming outbreak. The aim of the present study was therefore to investigate if differences in tail......:00 h-14:00 h from weaning until a tail biting outbreak. An outbreak (day 0) occurred when at least four pigs had a tail damage, regardless of wound freshness. On average 7.6 (SD 4.3) pigs had a damaged tail (scratches + wound) in T-pens on day 0. Tail posture and behaviour (activity, eating...

  6. Effects of various tailings covers on radon gas emanation from pyritic uranium tailings

    International Nuclear Information System (INIS)

    Dave, N.K.; Lim, T.P.

    1987-01-01

    Radon emanation studies were carried out at an inactive pyritic uranium tailings site in Elliot Lake, Ontario, Canada, to evaluate the effects of various existing dry and wet covers on radon flux rates. Measurements were taken using activated charcoal cartridges for various surface covers consisting of bare, vegetated, acidophilic moss with high degree of water saturation, compacted crushed rock and gravel, and winter snow. The results showed that at a given site, there was no significant difference in radon emanation rates between various tailings covers and bare tailings. In particular, no increase In radon emanation rates from vegetated areas compared to bare tailings was observed. Radon emanation rates varied spatially depending on tailings grain size, porosity, moisture content and on pressure and water table variations. The emanation rates were higher for tailings with low water contents compared to those for wet and moss covered tailings

  7. Dynamics of runaway tails with time-dependent sub-Dreicer dc fields in magnetized plasmas

    International Nuclear Information System (INIS)

    Moghaddam-Taaheri, E.; Vlahos, L.

    1987-01-01

    The evolution of runaway tails driven by sub-Dreicer time-dependent dc fields in a magnetized plasma are studied numerically using a quasilinear code based on the Ritz--Galerkin method and finite elements. It is found that the runaway tail maintained a negative slope during the dc field increase. Depending on the values of the dc electric field at t = 0 and the electron gyrofrequency to the plasma frequency ratio the runaway tail became unstable to the anomalous Doppler resonance or remained stable before the saturation of the dc field at some maximum value. The systems that remained stable during this stage became unstable to the anomalous Doppler or the Cerenkov resonances when the dc field was kept at the saturation level or decreased. Once the instability is triggered, the runaway tail is isotropized

  8. Dynamics of runaway tails with time-dependent sub-Dreicer dc fields in magnetized plasmas

    Science.gov (United States)

    Moghaddam-Taaheri, E.; Vlahos, L.

    1987-01-01

    The evolution of runaway tails driven by sub-Dreicer time-dependent dc fields in a magnetized plasma are studied numerically using a quasi-linear code based on the Ritz-Galerkin method and finite elements. It is found that the runaway tail maintained a negative slope during the dc field increase. Depending on the values of the dc electric field at t = 0 and the electron gyrofrequency to the plasma frequency ratio the runaway tail became unstable to the anomalous Doppler resonance or remained stable before the saturation of the dc field at some maximum value. The systems that remained stable during this stage became unstable to the anomalous Doppler or the Cerenkov resonances when the dc field was kept at the saturation level or decreased. Once the instability is triggered, the runaway tail is isotropized.

  9. Asymmetric Extreme Tails and Prospective Utility of Momentum Returns

    NARCIS (Netherlands)

    Stork, P.A.; Gregory-Allen, R.; Lu, H.

    2012-01-01

    We use extreme value theory to analyse the tails of a momentum strategy's return distribution. The asymmetry between the fat left tail and thin right tail strongly reduces a momentum strategy's prospective utility levels. © 2012 Elsevier B.V.

  10. Basic description of tailings from Aitik focusing on mechanical behavior

    OpenAIRE

    Bhanbhro, Riaz; Knutsson, Roger; Rodriguez, Juan; Edeskär, Tommy; Knutsson, Sven

    2013-01-01

    Tailings are artificial granular materials that behave different as compared to natural soil of equal grain sizes. Tailings particle sizes, shapes, gradation and mechanical behavior may influence the performance of tailings dams. Hence it is essential to understand the tailings materials in depth. This article describes present studies being carried out on Aitik tailings. Basic tailings characteristics including specific gravity, phase relationships, particle sizes, particle shapes and direct...

  11. Ilmenite Mineral's Recovery from Beach Sand Tailings

    International Nuclear Information System (INIS)

    Mulaba-Bafubiandi, Antoine F.; Mukendi-Ngalula, David; Waanders, Frans B.

    2002-01-01

    The mineral ilmenite is the major source of rutile for industrial use and is of interest to paint and fertiliser industries. Enormous unutilised tailing dams lie on the eastern coast of the South Africa. Although covered by a simulation of the original indigenous vegetation, these tailings are still ilmenite bearing and of economic value. Tailings emanating from beach sand mineral slimes dams of the Kwazulu-Natal area (South Africa) have been processed. Screening, flotation, spiral concentration and magnetic separation methods were used either separately or successively. The present work sheds light on alternative routes for the extraction of the ilmenite, from these tailings. It moreover points out the usefulness of the Moessbauer spectroscopy in the mineral processing product monitoring. Tailings from the beach sands were used in the present study after the economic industrial minerals zirconia, ilmenite and rutile had been extracted in previous mining operations. About 61% natural ilmenite recovery was observed in the flotation concentrate of a Humphrey Spiral concentrate while a 62% recovery of hematite was found in the flotation tailings. The combination of screening, spiral concentration and magnetic separation, and flotation yielded a product with the highest ilmenite and hematite concentration being 71% and 19%, respectively. A natural ilmenite mineral, containing 87% ilmenite and 13% hematite, could be produced and extracted from the tailings of the flotation process, collected subsequently to the spiral concentration and the initial screening.

  12. The evolution of tail weaponization in amniotes.

    Science.gov (United States)

    Arbour, Victoria M; Zanno, Lindsay E

    2018-01-31

    Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not well understood. Here, we investigate the evolution of tail weaponry in amniotes, a rare form of weaponry that nonetheless evolved independently among a broad spectrum of life including mammals, turtles and dinosaurs. Using phylogenetic comparative methods, we test for links between morphology, ecology and behaviour in extant amniotes known to use the tail as a weapon, and in extinct taxa bearing osseous tail armaments. We find robust ecological and morphological correlates of both tail lashing behaviour and bony tail weaponry, including large body size, body armour and herbivory, suggesting these life-history parameters factor into the evolution of antipredator behaviours and tail armaments. We suggest that the evolution of tail weaponry is rare because large, armoured herbivores are uncommon in extant terrestrial faunas, as they have been throughout evolutionary history. © 2018 The Author(s).

  13. APPLICATION OF POSTFLOTATION TAILINGS IN HYDROENGINEERING STRUCTURES

    Directory of Open Access Journals (Sweden)

    Katarzyna Stefaniak

    2017-01-01

    Full Text Available Economic development stimulated by the increased demand for production of consumer goods and the growing human population result in increasing amounts of various wastes, including tailings. The mining industry in Poland, comprising also mining of non-ferrous metal ores, is a strategic branch of the national economy and at the same time a leading waste producer. Tailings management is a significant problem both in Poland and worldwide. Frequently considerable amounts of wastes are accumulated in mine spoil tips, in areas not always suitable for their deposition, thus leading to the degradation of the surrounding environment. At the huge volume of produced wastes their rational and economically viable management is becoming crucial. On the other hand, depletion of natural aggregate deposits is an important incentive to search for substitutes, which would be suitable for the development of road infrastructure or which could be used in earth structure engineering to construct hydroengineering objects. Since no profitable recovery technologies are available at present, tailings generated by copper mining are deposited in tailings storage facilities. The largest and at the same time the only currently operating facility in Poland is the Żelazny Most Mining Tailings Storage Facility, belonging to KGHM Polska Miedź S.A. The paper presents criteria for material quality and density imposed on the material embedded in the static core of the tailings pond dam. For this purpose studies were conducted to confirm applicability of sorted tailings as a material for the construction of earth structures.

  14. Engineering assessment of inactive uranium mill tailings

    International Nuclear Information System (INIS)

    1981-07-01

    The Grand Junction site has been reevaluated in order to revise the October 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Grand Junction, Colorado. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.9 million tons of tailings at the Grand Junction site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation are also factors. The eight alternative actions presented herein range from millsite and off-site decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Options II through VIII). Cost estimates for the eight options range from about $10,200,000 for stabilization in-place to about $39,500,000 for disposal in the DeBeque area, at a distance of about 35 mi, using transportation by rail. If transportation to DeBeque were by truck, the cost estimated to be about $41,900,000. Three principal alternatives for the reprocessing of the Grand Junction tailings were examined: (a) heap leaching; (b) treatment at an existing mill; and (c) reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be about $200/lb by heap leach and $150/lb by conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Therefore, reprocessing the tailings for uranium recovery appears not to be economically attractive

  15. Engineering assessment of inactive uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    1981-07-01

    The Grand Junction site has been reevaluated in order to revise the October 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Grand Junction, Colorado. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.9 million tons of tailings at the Grand Junction site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation are also factors. The eight alternative actions presented herein range from millsite and off-site decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Options II through VIII). Cost estimates for the eight options range from about $10,200,000 for stabilization in-place to about $39,500,000 for disposal in the DeBeque area, at a distance of about 35 mi, using transportation by rail. If transportation to DeBeque were by truck, the cost estimated to be about $41,900,000. Three principal alternatives for the reprocessing of the Grand Junction tailings were examined: (a) heap leaching; (b) treatment at an existing mill; and (c) reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be about $200/lb by heap leach and $150/lb by conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Therefore, reprocessing the tailings for uranium recovery appears not to be economically attractive.

  16. Atmospheric pressure plasma accelerates tail regeneration in tadpoles Xenopus laevis

    Science.gov (United States)

    Rivie, A.; Martus, K.; Menon, J.

    2017-08-01

    Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema - a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

  17. Understanding the heavy-tailed dynamics in human behavior

    Science.gov (United States)

    Ross, Gordon J.; Jones, Tim

    2015-06-01

    The recent availability of electronic data sets containing large volumes of communication data has made it possible to study human behavior on a larger scale than ever before. From this, it has been discovered that across a diverse range of data sets, the interevent times between consecutive communication events obey heavy-tailed power law dynamics. Explaining this has proved controversial, and two distinct hypotheses have emerged. The first holds that these power laws are fundamental, and arise from the mechanisms such as priority queuing that humans use to schedule tasks. The second holds that they are statistical artifacts which only occur in aggregated data when features such as circadian rhythms and burstiness are ignored. We use a large social media data set to test these hypotheses, and find that although models that incorporate circadian rhythms and burstiness do explain part of the observed heavy tails, there is residual unexplained heavy-tail behavior which suggests a more fundamental cause. Based on this, we develop a quantitative model of human behavior which improves on existing approaches and gives insight into the mechanisms underlying human interactions.

  18. Cameco engineered tailings program: linking research with industrial processes for improved tailings performance

    International Nuclear Information System (INIS)

    Kotzer, T.; Hendry, M.J.

    2011-01-01

    The waste product from uranium mining and milling that generates the greatest public and regulatory concern is tailings. The tailings contain all of the mined material except uranium plus a host of processing reagents. These minerals and compounds have the potential to harm the local environment if not deposited in a fashion that is both geochemically and geotechnically stable. Environmental leadership impels Cameco Corporation to ensure that the methods used to dispose of tailings are at the forefront of best available technologies whereby tailings production results in a product with geotechnical and geochemical characteristics that minimize the environmental impact associated with long-term storage of this product. Cameco has developed an Engineered Tailings (ET) program to ensure optimization of long-term tailings performance and minimal impacts of elements of concern (EOCs) to the receiving environment, regardless of the ore being milled. Within this program chemical and physical performance of tailings from geochemical and geotechnical investigations and baseline environmental data, integrated with regulatory requirements and corporate commitments, will be used to evaluate and set criteria for mill- and tailings management facilities-based chemical and physical tailings characteristics, identify key knowledge gaps, prioritize areas of concern and implement appropriate responses. This paper provides an overview of the Engineered Tailings program, the research being conducted as part of the ET program, and how it links with present and future Cameco operations. (author)

  19. Characterization and treatment of artisanal gold mine tailings

    International Nuclear Information System (INIS)

    Andrade Lima, L.R.P. de; Bernardez, L.A.; Barbosa, L.A.D.

    2008-01-01

    The solid waste generated by artisanal gold mining, with high mercury and gold contents, can be found in several areas in the South America. The present study focused on the tailings of an artisanal gold mine area located in the Brazilian northeastern. Samples of the mine tailings were taken and used to perform a physical and chemical characterization study using X-ray diffraction, scanning electron microscopy, neutron activation, X-ray fluorescence, induced coupled plasma-mass spectrometry, among others analytical methods. The results indicate that the material is composed mainly by quartz and goethite, the characteristic size of the particles (d 50 ) is about 150 μm, and the density is close of that of quartz. The main constituents are silicon, iron, and aluminum. The tailings gold content is of about 1.8 mg/kg and the mercury content is of about 10 mg/kg. A remarkable feature of this solid waste is that the gold and mercury are both concentrated in both the fine and the coarse particles, but not in particles of intermediary size. Leaching studies indicated that the tailings are stable in weak organic acids, but soluble in alkaline and aired cyanide solutions, in which 89% of gold and 100% of mercury are extracted in 24 h. Electroleaching experiments, performed using sodium chloride as electrolyte, indicated that mercury and gold are extracted simultaneously and the recovery of both metals can be as high as 70% in 4 h. In addition, chromium, nickel, and lead are found in relatively large amounts in the solution, which indicate an effectively action of the electroleaching method to clean up solid wastes contaminated with metals

  20. Cameco engineered tailings program: linking applied research with industrial processes for improved tailings performance

    International Nuclear Information System (INIS)

    Kotzer, T.G.

    2010-01-01

    'Full text:' Mine tailings at Cameco's operations are by-products of milling uranium ore having variable concentrations of uranium, metals, oxyanions and trace elements or elements of concern (EOC). Cameco has undertaken an Engineered Tailings (ET) program to optimize tailings performance and minimize environmental EOC impacts, regardless of the milled ore source. Applied geochemical and geotechnical tailings research is key within the ET program. In-situ drilling and experimental programs are used to understand long-term tailings behaviour and help validate source term predictions. Within this, the ET program proactively aids in the development of mill-based processes for production of tailings having improved long-term stability. (author)

  1. Some properties of Suncor oil sands tailings

    Energy Technology Data Exchange (ETDEWEB)

    Guo, C.; Wells, P.S. [Suncor Energy, Fort McMurray, AB (Canada)

    2010-07-01

    This PowerPoint presentation discussed a pond assessment program conducted by Suncor to determine the properties of mature fine tailings (MFT) and composite tailings (CT) at reclaimed and unreclaimed sites. Mudline and sonar depth sounding techniques were used to determine solids contents. A wire line sampler provided point depth samples used for laboratory analyses. Continuous drill samples were obtained in order to characterize bottom fines and clay content. A flow penetration tests was used to determine the undrained shear strength of the soft tailings. A 3-D block model was then used to estimate soft material properties and to generate material distribution volumes and tonnages for different property ranges. The study showed that the block modelling techniques provide a more accurate tailings pond assessment than traditional approaches. While slow, ongoing static consolidation was observed, surface capping and artificial dewatering are required to provide trafficable ground for the final reclamation of the sites. tabs., figs.

  2. Unique structural features facilitate lizard tail autotomy.

    Directory of Open Access Journals (Sweden)

    Kristian W Sanggaard

    Full Text Available Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed that tail shedding by the Tokay gecko (Gekko gecko and the associated extracellular matrix (ECM rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail of Gekko gecko was pre-severed at distinct sites and that its structural integrity depended on the adhesion between these segments.

  3. BIOMECHANICS. Why the seahorse tail is square.

    Science.gov (United States)

    Porter, Michael M; Adriaens, Dominique; Hatton, Ross L; Meyers, Marc A; McKittrick, Joanna

    2015-07-03

    Whereas the predominant shapes of most animal tails are cylindrical, seahorse tails are square prisms. Seahorses use their tails as flexible grasping appendages, in spite of a rigid bony armor that fully encases their bodies. We explore the mechanics of two three-dimensional-printed models that mimic either the natural (square prism) or hypothetical (cylindrical) architecture of a seahorse tail to uncover whether or not the square geometry provides any functional advantages. Our results show that the square prism is more resilient when crushed and provides a mechanism for preserving articulatory organization upon extensive bending and twisting, as compared with its cylindrical counterpart. Thus, the square architecture is better than the circular one in the context of two integrated functions: grasping ability and crushing resistance. Copyright © 2015, American Association for the Advancement of Science.

  4. Elemental characterization of Tummalapalle uranium mill tailing

    International Nuclear Information System (INIS)

    Patra, A.C.; Sahoo, S.K.; Thakur, V.K.; Dubey, J.S.; Jha, S.K.; Tripathi, R.M.; Sharma, D.B.

    2018-01-01

    Elements are present in environmental matrices at varying concentrations. Their levels may increase due to anthropogenic activities like transportation, industrial activities, agriculture, urbanization and human activities. Trace elements can be classified as potentially toxic (eg. cadmium, arsenic, mercury, lead, nickel), probably essential (eg. cobalt, vanadium) and essential (eg. iron, zinc, copper, selenium, manganese). Due to the expansion of the Indian Nuclear Power Programme, new uranium mining sites are coming up. Mining and milling produce large quantities of low active mill tailings contained in engineered Tailings Ponds. The tailings are amenable for interaction with the geochemical forces and can act as potential sources of contamination. Thus it is necessary to ascertain the concentrations of elements that are present therein. In this paper we aim to characterize the uranium tailings generated from Tummalapalle uranium mining facility in Kadappa district, Andhra Pradesh, India

  5. On Estimation and Testing for Pareto Tails

    Czech Academy of Sciences Publication Activity Database

    Jordanova, P.; Stehlík, M.; Fabián, Zdeněk; Střelec, L.

    2013-01-01

    Roč. 22, č. 1 (2013), s. 89-108 ISSN 0204-9805 Institutional support: RVO:67985807 Keywords : testing against heavy tails * asymptotic properties of estimators * point estimation Subject RIV: BB - Applied Statistics, Operational Research

  6. Electron-cyclotron-resonant-heated electron distribution functions

    International Nuclear Information System (INIS)

    Matsuda, Y.; Nevins, W.M.; Cohen, R.H.

    1981-01-01

    Recent studies at Lawrence Livermore National Laboratory (LLNL) with a bounce-averaged Fokker-Planck code indicate that the energetic electron tail formed by electron-cyclotron resonant heating (ECRH) at the second harmonic is not Maxwellian. We present the results of our bounce-averaged Fokker-Planck code along with some simple analytic models of hot-electron distribution functions

  7. Electrodialytic remediation of suspended mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrian; Pino, Denisse

    2008-01-01

    This work shows the laboratory results of nine electrodialytic remediation experiments on copper mine tailings. A newly designed remediation cell, where the solids were kept in suspension by airflow, was tested. The results show that electric current could remove copper from suspended tailings...... efficiency from 1% to 80% compared to experiments with no stirring but with the same operational conditions. This showed the crucial importance of having the solids in suspension and not settled during the remediation....

  8. Electrodialytic Remediation of Copper Mine Tailings

    DEFF Research Database (Denmark)

    Hansen, H.K.; Rojo, A.; Ottosen, L.M.

    2012-01-01

    This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analysed, such as remediation time, addition of desorbing agents, and the use of pulsed electrical fields.......This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analysed, such as remediation time, addition of desorbing agents, and the use of pulsed electrical fields....

  9. TIDAL TAILS OF MINOR MERGERS. II. COMPARING STAR FORMATION IN THE TIDAL TAILS OF NGC 2782

    Energy Technology Data Exchange (ETDEWEB)

    Knierman, Karen A.; Scowen, Paul; Veach, Todd; Groppi, Christopher [School of Earth and Space Exploration, Arizona State University, 550 E. Tyler Mall, Room PSF-686 (P.O. Box 871404), Tempe, AZ 85287-1404 (United States); Mullan, Brendan; Charlton, Jane [Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab, University Park, PA (United States); Konstantopoulos, Iraklis [Australian Astronomical Observatory, P.O. Box 915, North Ryde NSW 1670 (Australia); Knezek, Patricia M., E-mail: karen.knierman@asu.edu, E-mail: paul.scowen@asu.edu, E-mail: tveach@asu.edu, E-mail: cgroppi@asu.edu, E-mail: mullan@astro.psu.edu, E-mail: iraklis@aao.gov.au, E-mail: pknezek@noao.edu [WIYN Consortium, Inc., 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)

    2013-09-10

    The peculiar spiral NGC 2782 is the result of a minor merger with a mass ratio {approx}4: 1 occurring {approx}200 Myr ago. This merger produced a molecular and H I-rich, optically bright eastern tail and an H I-rich, optically faint western tail. Non-detection of CO in the western tail by Braine et al. suggested that star formation had not yet begun. However, deep UBVR and H{alpha} narrowband images show evidence of recent star formation in the western tail, though it lacks massive star clusters and cluster complexes. Using Herschel PACS spectroscopy, we discover 158 {mu}m [C II] emission at the location of the three most luminous H{alpha} sources in the eastern tail, but not at the location of the even brighter H{alpha} source in the western tail. The western tail is found to have a normal star formation efficiency (SFE), but the eastern tail has a low SFE. The lack of CO and [C II] emission suggests that the western tail H II region may have a low carbon abundance and be undergoing its first star formation. The western tail is more efficient at forming stars, but lacks massive clusters. We propose that the low SFE in the eastern tail may be due to its formation as a splash region where gas heating is important even though it has sufficient molecular and neutral gas to make massive star clusters. The western tail, which has lower gas surface density and does not form high-mass star clusters, is a tidally formed region where gravitational compression likely enhances star formation.

  10. TIDAL TAILS OF MINOR MERGERS. II. COMPARING STAR FORMATION IN THE TIDAL TAILS OF NGC 2782

    International Nuclear Information System (INIS)

    Knierman, Karen A.; Scowen, Paul; Veach, Todd; Groppi, Christopher; Mullan, Brendan; Charlton, Jane; Konstantopoulos, Iraklis; Knezek, Patricia M.

    2013-01-01

    The peculiar spiral NGC 2782 is the result of a minor merger with a mass ratio ∼4: 1 occurring ∼200 Myr ago. This merger produced a molecular and H I-rich, optically bright eastern tail and an H I-rich, optically faint western tail. Non-detection of CO in the western tail by Braine et al. suggested that star formation had not yet begun. However, deep UBVR and Hα narrowband images show evidence of recent star formation in the western tail, though it lacks massive star clusters and cluster complexes. Using Herschel PACS spectroscopy, we discover 158 μm [C II] emission at the location of the three most luminous Hα sources in the eastern tail, but not at the location of the even brighter Hα source in the western tail. The western tail is found to have a normal star formation efficiency (SFE), but the eastern tail has a low SFE. The lack of CO and [C II] emission suggests that the western tail H II region may have a low carbon abundance and be undergoing its first star formation. The western tail is more efficient at forming stars, but lacks massive clusters. We propose that the low SFE in the eastern tail may be due to its formation as a splash region where gas heating is important even though it has sufficient molecular and neutral gas to make massive star clusters. The western tail, which has lower gas surface density and does not form high-mass star clusters, is a tidally formed region where gravitational compression likely enhances star formation

  11. Canadian experience with uranium tailings disposal

    International Nuclear Information System (INIS)

    Culver, K.B.

    1982-06-01

    During the first years of uranium production in Canada uranium tailings were discharged directly into valleys or lakes near the mill. Treatment with barium chloride to precipitate radium began in 1965 at the Nordic Mine at Elliot Lake, Ontario. In the mid-60s and early 70s water quality studies indicated that discharges from uranium tailings areas were causing degradation to the upper part of the Serpent River water system. Studies into acid generation, revegetation, and leaching of radium were initiated by the mining companies and resulted in the construction of treatment plants at a number of sites. Abandoned tailings sites were revegetated. At hearings into the expansion of the Elliot Lake operations the issue of tailings management was a major item for discussion. As a result federal and provincial agencies developed guidelines for the siting and development of urnaium tailings areas prior to issuing operating licences. Western Canadian uranium producers do not have the acid generation problem of the Elliot Lake operations. The Rabbit Lake mill uses settling ponds followed by filtration. High-grade tailings from Cluff Lake are sealed in concrete and buried. Uranium producers feel that the interim criteria developed by the Atomic Energy Control Board, if adopted, would have a harmful effect on the viability of the Canadian uranium industry

  12. Four tails problems for dynamical collapse theories

    Science.gov (United States)

    McQueen, Kelvin J.

    2015-02-01

    The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the tails problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct tails problems. The first (bare tails problem) and second (structured tails problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse tails problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (tails problem dilemma) shows that solving the third by replacing the Gaussian with a non-Gaussian collapse function introduces new conflict with relativity theory.

  13. Consistency based correlations for tailings consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Azam, S.; Paul, A.C. [Regina Univ., Regina, SK (Canada). Environmental Systems Engineering

    2010-07-01

    The extraction of oil, uranium, metals and mineral resources from the earth generates significant amounts of tailings slurry. The tailings are contained in a disposal area with perimeter dykes constructed from the coarser fraction of the slurry. There are many unique challenges pertaining to the management of the containment facilities for several decades beyond mine closure that are a result of the slow settling rates of the fines and the high standing toxic waters. Many tailings dam failures in different parts of the world have been reported to result in significant contaminant releases causing public concern over the conventional practice of tailings disposal. Therefore, in order to reduce and minimize the environmental footprint, the fluid tailings need to undergo efficient consolidation. This paper presented an investigation into the consolidation behaviour of tailings in conjunction with soil consistency that captured physicochemical interactions. The paper discussed the large strain consolidation behaviour (volume compressibility and hydraulic conductivity) of six fine-grained soil slurries based on published data. The paper provided background information on the study and presented the research methodology. The geotechnical index properties of the selected materials were also presented. The large strain consolidation, volume compressibility correlations, and hydraulic conductivity correlations were provided. It was concluded that the normalized void ratio best described volume compressibility whereas liquidity index best explained the hydraulic conductivity. 17 refs., 3 tabs., 4 figs.

  14. The Sodium Tail of the Moon

    Science.gov (United States)

    Matta, M.; Smith, S.; Baumgardner, J.; Wilson, J.; Martinis, C.; Mendillo, M.

    2009-01-01

    During the few days centered about new Moon, the lunar surface is optically hidden from Earth-based observers. However, the Moon still offers an observable: an extended sodium tail. The lunar sodium tail is the escaping "hot" component of a coma-like exosphere of sodium generated by photon-stimulated desorption, solar wind sputtering and meteoroid impact. Neutral sodium atoms escaping lunar gravity experience solar radiation pressure that drives them into the anti-solar direction forming a comet-like tail. During new Moon time, the geometry of the Sun, Moon and Earth is such that the anti-sunward sodium flux is perturbed by the terrestrial gravitational field resulting in its focusing into a dense core that extends beyond the Earth. An all-sky camera situated at the El Leoncito Observatory (CASLEO) in Argentina has been successfully imaging this tail through a sodium filter at each lunation since April 2006. This paper reports on the results of the brightness of the lunar sodium tail spanning 31 lunations between April 2006 and September 2008. Brightness variability trends are compared with both sporadic and shower meteor activity, solar wind proton energy flux and solar near ultra violet (NUV) patterns for possible correlations. Results suggest minimal variability in the brightness of the observed lunar sodium tail, generally uncorrelated with any single source, yet consistent with a multi-year period of minimal solar activity and non-intense meteoric fluxes.

  15. Attitudes of Dutch Pig Farmers Towards Tail Biting and Tail Docking

    OpenAIRE

    Bracke, M.B.M.; Lauwere, de, C.C.; Wind, S.M.M.; Zonderland, J.J.

    2013-01-01

    The Dutch policy objective of a fully sustainable livestock sector without mutilations by 2023 is not compatible with the routine practice of tail docking to minimize the risk of tail biting. To examine farmer attitudes towards docking, a telephone survey was conducted among 487 conventional and 33 organic Dutch pig farmers. “Biting” (of tails, ears, or limbs) was identified by the farmers as a main welfare problem in pig farming. About half of the farmers reported to have no tail biting prob...

  16. Microbially-accelerated consolidation of oil sands tailings. Pathway II: solid phase biogeochemistry

    Directory of Open Access Journals (Sweden)

    Tariq eSiddique

    2014-03-01

    Full Text Available Consolidation of clay particles in aqueous tailings suspensions is a major obstacle to effective management of oil sands tailings ponds in northern Alberta, Canada. We have observed that microorganisms indigenous to the tailings ponds accelerate consolidation of mature fine tailings (MFT during active metabolism by using two biogeochemical pathways. In Pathway I, microbes alter porewater chemistry to indirectly increase consolidation of MFT. Here, we describe Pathway II comprising significant, direct and complementary biogeochemical reactions with MFT mineral surfaces. An anaerobic microbial community comprising Bacteria (predominantly Clostridiales, Synergistaceae and Desulfobulbaceae and Archaea (Methanolinea/Methanoregula and Methanosaeta transformed FeIII minerals in MFT to amorphous FeII minerals during methanogenic metabolism of an added organic substrate. Synchrotron analyses suggested that ferrihydrite (5Fe2O3. 9H2O and goethite (α-FeOOH were the dominant FeIII minerals in MFT. The formation of amorphous iron sulfide (FeS and possibly green rust entrapped and masked electronegative clay surfaces in amended MFT. Both Pathways I and II reduced the surface charge potential (repulsive forces of the clay particles in MFT, which aided aggregation of clays and formation of networks of pores, as visualized using cryo-scanning electron microscopy. These reactions facilitated the egress of porewater from MFT and increased consolidation of tailings solids. These results have large-scale implications for management and reclamation of oil sands tailings ponds, a burgeoning environmental issue for the public and government regulators.

  17. Microbially-accelerated consolidation of oil sands tailings. Pathway II: solid phase biogeochemistry.

    Science.gov (United States)

    Siddique, Tariq; Kuznetsov, Petr; Kuznetsova, Alsu; Li, Carmen; Young, Rozlyn; Arocena, Joselito M; Foght, Julia M

    2014-01-01

    Consolidation of clay particles in aqueous tailings suspensions is a major obstacle to effective management of oil sands tailings ponds in northern Alberta, Canada. We have observed that microorganisms indigenous to the tailings ponds accelerate consolidation of mature fine tailings (MFT) during active metabolism by using two biogeochemical pathways. In Pathway I, microbes alter porewater chemistry to indirectly increase consolidation of MFT. Here, we describe Pathway II comprising significant, direct and complementary biogeochemical reactions with MFT mineral surfaces. An anaerobic microbial community comprising Bacteria (predominantly Clostridiales, Synergistaceae, and Desulfobulbaceae) and Archaea (Methanolinea/Methanoregula and Methanosaeta) transformed Fe(III) minerals in MFT to amorphous Fe(II) minerals during methanogenic metabolism of an added organic substrate. Synchrotron analyses suggested that ferrihydrite (5Fe2O3. 9H2O) and goethite (α-FeOOH) were the dominant Fe(III) minerals in MFT. The formation of amorphous iron sulfide (FeS) and possibly green rust entrapped and masked electronegative clay surfaces in amended MFT. Both Pathways I and II reduced the surface charge potential (repulsive forces) of the clay particles in MFT, which aided aggregation of clays and formation of networks of pores, as visualized using cryo-scanning electron microscopy (SEM). These reactions facilitated the egress of porewater from MFT and increased consolidation of tailings solids. These results have large-scale implications for management and reclamation of oil sands tailings ponds, a burgeoning environmental issue for the public and government regulators.

  18. Dewatering Behaviour of Fine Oil Sands Tailings : An Experimental Study

    NARCIS (Netherlands)

    Yao, Y.

    2016-01-01

    Oil sands tailings are a warm aqueous suspension of sand, silt, clay, residual bitumen and naphtha. The tailings are hydraulically transported and stored in tailing ponds where they segregate, with the sand settling from suspension forming beaches and the remaining tailings flowing to the middle of

  19. Activity, tail loss, growth and survivorship of male Psammodromus algirus

    OpenAIRE

    Salvador Milla, Alfredo; Veiga, José Pablo

    2005-01-01

    Males with autotomized tail were sighted more often and moved longer distances than males with complete tail. There were no significant differences in survival between the two groups. The increase of snout-vent lenght at emergence the following year was significantly lower for males with autotomized tail than for males with complete tail.

  20. Limits theorems for tail processes with applications tointermediate quantile estimation

    NARCIS (Netherlands)

    Einmahl, J.H.J.

    1992-01-01

    A description of the weak and strong limiting behaviour of weighted uniform tail empirical and tail quantile processes is given. The results for the tail quantile process are applied to obtain weak and strong functional limit theorems for a weighted non-uniform tail-quantile-type process based on a

  1. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger

    International Nuclear Information System (INIS)

    Déjeant, Adrien; Galoisy, Laurence; Roy, Régis; Calas, Georges; Boekhout, Flora; Phrommavanh, Vannapha; Descostes, Michael

    2016-01-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam — Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. - Highlights: • The evolution of U distribution and speciation in mill tailings is investigated. • High resolution satellite images provide useful information on tailings evolution. • U and many other elements are enriched in a sulfate-rich duricrust. • Formation of

  2. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger

    Energy Technology Data Exchange (ETDEWEB)

    Déjeant, Adrien, E-mail: adrien.dejeant@normalesup.org [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Paris Diderot — Paris VII, 5 rue Thomas Mann, 75013 Paris (France); Galoisy, Laurence [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Roy, Régis [AREVA Mines — Geoscience Department, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France); Calas, Georges; Boekhout, Flora [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Phrommavanh, Vannapha; Descostes, Michael [AREVA Mines — R& D Department, BAL 0414C-2, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France)

    2016-03-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam — Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. - Highlights: • The evolution of U distribution and speciation in mill tailings is investigated. • High resolution satellite images provide useful information on tailings evolution. • U and many other elements are enriched in a sulfate-rich duricrust. • Formation of

  3. Diagnostic analysis of electrodialysis in mine tailing materials

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Ribeiro, Alexandra B.; Mateus, Eduardo

    2007-01-01

    Removal of heavy metals from mine tailings and soil contaminated by copper mining activities was studied under batch electrodialytic conditions. Two types of mine tailings were treated: (i) freshly produced tailings coming directly from the flotation process, and (ii) tailings deposited...... in a tailings pond, for approximately 20 years. The main contaminant was copper-found in concentration around 800-1800 ppm. The fractionation of copper and other characteristics of the tailings differ for the two tailings, indicating natural oxidation reactions in the old deposited ones. Electrodialytical...

  4. Study and characterization of tobacco mosaic virus head-to-tail assembly assisted by aniline polymerization.

    Science.gov (United States)

    Niu, Zhongwei; Bruckman, Michael; Kotakadi, Venkata S; He, Jinbo; Emrick, Todd; Russell, Thomas P; Yang, Lin; Wang, Qian

    2006-07-28

    One-dimensional composite nanofibres with narrow dispersity, high aspect ratio and high processibility have been fabricated by head-to-tail self-assembly of rod-like tobacco mosaic virus assisted by aniline polymerization, which can promote many potential applications including electronics, optics, sensing and biomedical engineering.

  5. Mobility and Attenuation Dynamics of Potentially Toxic Chemical Species at an Abandoned Copper Mine Tailings Dump

    Directory of Open Access Journals (Sweden)

    Wilson Mugera Gitari

    2018-02-01

    Full Text Available Large volumes of disposed mine tailings abound in several regions of South Africa, as a consequence of unregulated, unsustainable long years of mining activities. Tailings dumps occupy a large volume of valuable land, and present a potential risk for aquatic systems, through leaching of potentially toxic chemical species. This paper reports on the evaluation of the geochemical processes controlling the mobility of potentially toxic chemical species within the tailings profile, and their potential risk with regard to surface and groundwater systems. Combination of X-ray fluorescence (XRF, X-ray diffraction (XRD, and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS techniques, show that the tailing profiles are uniform, weakly altered, and vary slightly with depth in both physical and geochemical properties, as well as mineralogical composition. Mineralogical analysis showed the following order of abundance: quartz > epidote > chlorite > muscovite > calcite > hematite within the tailings profiles. The neutralization of the dominant alumino-silicate minerals and the absence of sulfidic minerals, have produced medium alkaline pH conditions (7.97–8.37 at all depths and low concentrations of dissolved Cu (20.21–47.9 µg/L, Zn (0.88–1.80 µg/L, Pb (0.27–0.34 µg/L, and SO42− (15.71–55.94 mg/L in the tailings profile leachates. The relative percentage leach for the potentially toxic chemical species was low in the aqueous phase (Ni 0.081%, Cu 0.006%, and Zn 0.05%. This indicates that the transport load of potentially toxic chemical species from tailings to the aqueous phase is very low. The precipitation of secondary hematite has an important known ability to trap and attenuate the mobility of potentially toxic chemical species (Cu, Zn, and Pb by adsorption on the surface area. Geochemical modelling MINTEQA2 showed that the tailings leachates were below saturation regarding oxyhydroxide minerals, but oversaturated with Cu

  6. FARADAY ROTATION IN THE TAIL OF THE PLANETARY NEBULA DeHt 5

    International Nuclear Information System (INIS)

    Ransom, R. R.; Kothes, R.; Wolleben, M.; Landecker, T. L.

    2010-01-01

    We present 1420 MHz polarization images of a 5 0 x 5 0 region around the planetary nebula (PN) DeHt 5. The images reveal narrow Faraday-rotation structures on the visible disk of DeHt 5, as well as two wider, tail-like, structures 'behind' DeHt 5. Though DeHt 5 is an old PN known to be interacting with the interstellar medium (ISM), a tail has not previously been identified for this object. The innermost tail is ∼3 pc long and runs away from the northeast edge of DeHt 5 in a direction roughly opposite that of the sky-projected space velocity of the white dwarf central star, WD 2218+706. We believe this tail to be the signature of ionized material ram-pressure stripped and deposited downstream during a >74,000 yr interaction between DeHt 5 and the ISM. We estimate the rotation measure (RM) through the inner tail to be -15 ± 5 rad m -2 , and, using a realistic estimate for the line-of-sight component of the ISM magnetic field around DeHt 5, derive an electron density in the inner tail of n e = 3.6 ± 1.8 cm -3 . Assuming the material is fully ionized, we estimate a total mass in the inner tail of 0.68 ± 0.33 M sun and predict that 0.49 ± 0.33 M sun was added during the PN-ISM interaction. The outermost tail consists of a series of three roughly circular components, which have a collective length of ∼11.0 pc. This tail is less conspicuous than the inner tail and may be the signature of the earlier interaction between the WD 2218+706 asymptotic giant branch (AGB) progenitor and the ISM. The results for the inner and outer tails are consistent with hydrodynamic simulations and may have implications for the PN missing-mass problem as well as for models which describe the impact of the deaths of intermediate-mass stars on the ISM.

  7. Electro-remediation of copper mine tailings. Comparing copper removal efficiencies for two tailings of different age

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Lamas, Victor; Gutierrez, Claudia

    2013-01-01

    This work compares and evaluates the copper removal efficiency when applying electric fields to two mine tailings originating from the same mine but of different age. Eight experiments were carried out - four on tailings deposited more than 20 years ago (old tailings) and four on tailings deposit...

  8. A new procedure for deep sea mining tailings disposal

    OpenAIRE

    Ma, W.; Schott, D.L.; Lodewijks, G.

    2017-01-01

    Deep sea mining tailings disposal is a new environmental challenge related to water pollution, mineral crust waste handling, and ocean biology. The objective of this paper is to propose a new tailings disposal procedure for the deep sea mining industry. Through comparisons of the tailings disposal methods which exist in on-land mining and the coastal mining fields, a new tailings disposal procedure, i.e., the submarine–backfill–dam–reuse (SBDR) tailings disposal procedure, is proposed. It com...

  9. Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs

    DEFF Research Database (Denmark)

    Herskin, M S; Thodberg, K; Jensen, Henrik Elvang

    2015-01-01

    % (n=19); or leaving 25% (n=11) of the tail length on the pigs. The piglets were docked between day 2 and 4 after birth using a gas-heated apparatus, and were kept under conventional conditions until slaughter at 22 weeks of age, where tails were removed and examined macroscopically and histologically...

  10. Tail Asymptotics for the Sum of two Heavy-tailed Dependent Risks

    DEFF Research Database (Denmark)

    Albrecher, H.; Asmussen, Søren

    Let X1,X2 denote positive exchangable heavy-tailed random variables with continuous marginal distribution function F. The asymptotic behavior of the tail of X1 + X2 is studied in a general copula framework and some bounds and extremal properties are provided. For more specific assumptions on F...

  11. Tailings neutralization and other alternatives for immobilizing toxic materials in tailings. Final report

    International Nuclear Information System (INIS)

    Opitz, B.E.; Sherwood, D.R.; Dodson, M.E.; Serne, R.J.

    1985-09-01

    This document, ''Tailing Neutralization and Other Alternatives for Immobilizing Toxic Materials in Tailings,'' is the final report in a series of six. It summarizes research completed since the beginning of the project. Three subtasks are included: Subtask A - Neutralization Methods Selection; Subtask B - Laboratory Analysis; and Subtask C - Field Testing. Subtask A reviews treatment processes from other industries to evaluate whether current waste technology from other fields is applicable to the uranium industry. This task also identifies several reagents that were tested for their effectiveness in treating acidic tailings and tailings solution in order to immobilize the contaminants associated with the acid waste. Subtask B describes the laboratory batch and column treatment studies performed on solid waste tailings and tailings solutions over the course of the project. The evaluation of several reagents identified in Subtask A was based on three criteria: (1) treated effluent water quality; (2) neutralized sludge handling and hydraulic properties; and (3) reagent costs and acid neutralizing efficiency. Subtask C presents a field demonstration plan that will evaluate the effectiveness, costs, and benefits of neutralizing acidic uranium mill tailings solution to reduce the potential leaching of toxic trace metals, radionuclides, and macro ions from a tailings impoundment. Details of the related research can be found in the documents listed in the ''Previous Documents in Series.'' 43 refs., 9 figs., 46 tabs

  12. Attitudes of Dutch Pig Farmers Towards Tail Biting and Tail Docking

    NARCIS (Netherlands)

    Bracke, M.B.M.; Lauwere, de C.C.; Wind, S.M.M.; Zonderland, J.J.

    2013-01-01

    The Dutch policy objective of a fully sustainable livestock sector without mutilations by 2023 is not compatible with the routine practice of tail docking to minimize the risk of tail biting. To examine farmer attitudes towards docking, a telephone survey was conducted among 487 conventional and 33

  13. Blast densification trials for oilsands tailings

    Energy Technology Data Exchange (ETDEWEB)

    Port, A. [Klohn Crippen Berger Ltd., Vancouver, BC (Canada); Martens, S. [Klohn Crippen Berger Ltd., Calgary, AB (Canada); Eaton, T. [Shell Canada Ltd., Calgary, AB (Canada)

    2010-07-01

    The Shell Canada Muskeg River Mine External Tailings Facility (ETF) is an upstream constructed tailings facility located near Fort McMurray, Alberta. Raises have incrementally stepped out over the beach since construction of the starter dam and deposition within standing water has left some parts of the beach in a loose state. In order to assess the effectiveness of blast densification, a blast densification trial program that was conducted in 2006 at the ETF. The primary purpose of the test program was to determine the effectiveness of blast densification in tailings containing layers and zones of bitumen. The paper described the site characterization and explosive compaction trial program, with particular reference to test layout; drilling methodology; and blasting and timing sequence. The paper also described the instrumentation, including the seismographs; high pressure electric piezometers; low pressure electric piezometers; vibrating wire piezometers; inclinometers; settlement gauges; and surveys. Trial observations and post-trial observations were also presented. It was concluded that controlled blasting techniques could be used to safely induce liquefaction in localized areas within the tailings deposit, with a resulting increase in the tailings density. 5 refs., 1 tab., 14 figs.

  14. Reclamation plans at uranium mill tailings sites

    International Nuclear Information System (INIS)

    Abt, S.R.; Nelson, J.D.

    1990-01-01

    Long-term stability of waste impoundments is of concern because of the long time periods over which various types of waste may remain active. Over the past decade much technology has been developed specifically for reclamation of uranium mill tailings impoundments. Aspects of this technology will be discussed here and is presented as also being directly applicable to reclamation of industrial waste impoundments in general. The paper discusses Title I and Title II sites which represent two different generations in uranium tailings impoundment construction. The comparison between the two represent differences in philosophies as well as in impoundment type. Reclamation of uranium mill tailings impoundments in the U.S. is controlled by Federal legislation, which has set forth the regulatory framework for reclamation plan approval. Title I requirements govern government owned inactive sites and Title II requirements govern active tailings impoundments or those operated by private industries. While the Title I and Title II designation may result in a slightly different regulatory process, reclamation of uranium tailings sites has the same. Differences between Title I and Title II reclamation plans to achieve surface stability relate primarily to the embankment and surface covers. The differences in the cover designs result from site-specific conditions, rather than from differences in engineering approaches or the regulatory process. This paper discusses the site-specific conditions that affect the selection of cover designs, and provides a comparative example to illustrate the effect of this condition

  15. Assessment of the underground disposal of tailings

    Energy Technology Data Exchange (ETDEWEB)

    Hutt, N M [Morwijk Enterprises Ltd., (Canada); Morin, K A [Normar Enterprises, (Canada)

    1995-06-01

    The Atomic Energy Control Board (AECB) of Canada is facing the issue of long-term disposal of uranium tailings. One option that has not been examined in sufficient detail for the AECB is the retrieval of tailings from surface impoundments and subsequent placement of those tailings in underground workings of mines. This report is structured like a catalogue of facts and information, with each paragraph presenting some concept, concern, theory, or case study involving the retrieval or placement of tailings. All relevant information, findings, interpretations, conclusions, and recommendations gathered during the course of this study are included. The Table of Contents illustrates the striking number of relevant topics and acts like a flowchart or checklist to ensure that an underground-disposal submission by a mining company has addressed relevant topics. This report explains in detail the implications of disturbing surface-impounded tailings for the purpose of placing only some of the volume underground. The cumulative environmental, safety, and monetary liabilities of such a partial scheme can be discouraging in some cases. (author). 244 refs., 47 tabs., 17 figs.

  16. Grouting of uranium mill tailings piles

    International Nuclear Information System (INIS)

    Boegly, W.J. Jr.; Tamura, T.; Williams, J.D.

    1984-03-01

    A program of remedial action was initiated for a number of inactive uranium mill tailings piles. These piles result from mining and processing of uranium ores to meet the nation's defense and nuclear power needs and represent a potential hazard to health and the environment. Possible remedial actions include the application of covers to reduce radon emissions and airborne transport of the tailings, liners to prevent groundwater contamination by leachates from the piles, physical or chemical stabilization of the tailings, or moving the piles to remote locations. Conventional installation of liners would require excavation of the piles to emplace the liner; however, utilization of grouting techniques, such as those used in civil engineering to stabilize soils, might be a potential method of producing a liner without excavation. Laboratory studies on groutability of uranium mill tailings were conducted using samples from three abandoned piles and employing a number of particulate and chemical grouts. These studies indicate that it is possible to alter the permeability of the tailings from ambient values of 10 -3 cm/s to values approaching 10 -7 cm/s using silicate grouts and to 10 -8 cm/s using acrylamide and acrylate grouts. An evaluation of grouting techniques, equipment required, and costs associated with grouting were also conducted and are presented. 10 references, 1 table

  17. Remote sensing to monitor uranium tailing sites

    International Nuclear Information System (INIS)

    1992-02-01

    This report concerns the feasibility of using remotely-sensed data for long-term monitoring of uranium tailings. Decommissioning of uranium mine tailings sites may require long-term monitoring to confirm that no unanticipated release of contaminants occurs. Traditional ground-based monitoring of specific criteria of concern would be a significant expense depending on the nature and frequency of the monitoring. The objective of this study was to evaluate whether available remote-sensing data and techniques were applicable to the long-term monitoring of tailings sites. This objective was met by evaluating to what extent the data and techniques could be used to identify and discriminate information useful for monitoring tailings sites. The cost associated with obtaining and interpreting this information was also evaluated. Satellite and aircraft remote-sensing-based activities were evaluated. A monitoring programme based on annual coverage of Landsat Thematic Mapper data is recommended. Immediately prior to and for several years after decommissioning of the tailings sites, airborne multispectral and thermal infrared surveys combined with field verification data are required in order to establish a baseline for the long-term satellite-based monitoring programme. More frequent airborne surveys may be required if rapidly changing phenomena require monitoring. The use of a geographic information system is recommended for the effective storage and manipulation of data accumulated over a number of years

  18. Assessment of the underground disposal of tailings

    International Nuclear Information System (INIS)

    Hutt, N.M.; Morin, K.A.

    1995-06-01

    The Atomic Energy Control Board (AECB) of Canada is facing the issue of long-term disposal of uranium tailings. One option that has not been examined in sufficient detail for the AECB is the retrieval of tailings from surface impoundments and subsequent placement of those tailings in underground workings of mines. This report is structured like a catalogue of facts and information, with each paragraph presenting some concept, concern, theory, or case study involving the retrieval or placement of tailings. All relevant information, findings, interpretations, conclusions, and recommendations gathered during the course of this study are included. The Table of Contents illustrates the striking number of relevant topics and acts like a flowchart or checklist to ensure that an underground-disposal submission by a mining company has addressed relevant topics. This report explains in detail the implications of disturbing surface-impounded tailings for the purpose of placing only some of the volume underground. The cumulative environmental, safety, and monetary liabilities of such a partial scheme can be discouraging in some cases. (author). 244 refs., 47 tabs., 17 figs

  19. Oil sands tailings preliminary ecological risk assessment

    International Nuclear Information System (INIS)

    1994-01-01

    Chemical data collected from various oil sands soil-tailings mixtures were used to determine the ecological risk that such tailings would pose to terrestrial wildlife at the surface of a reclaimed site. A methodology that could be used to evaluate the risks posed by various reclamation options (for dry land only) was proposed. Risks associated with other reclamation options, such as wet landscapes or deeper in-pit disposal, were not evaluated. Ten constituents (eight organic and two inorganic) were found to pose a threat to terrestrial biota. The relative contribution of different exposure pathways (water and food ingestion, incidental soil ingestion, inhalation) were studied by probabilistic models. Some physical and chemical reclamation alternatives which involve incorporating oil sands tailings in the landscape to produce a surface that could sustain a productive ecosystem, were described. 53 refs., 15 tabs., 3 figs

  20. Uranium tailings in the public eye

    International Nuclear Information System (INIS)

    Lyon, B.

    1976-01-01

    The ORNL field team visits to Grand Junction, Colorado, and to other sources of uranium mill tailings, are described. The radioactive hazards of these tailings, which are principally due to Th, Ra, Rn, and radon daughters, are discussed briefly. Government actions which were taken as a result of public concern are listed. The ORNL Health Physics Division mobile laboratory van and its use in assessing the tailings piles at Salt Lake City and elsewhere are described. The highest γ-ray background found was 155 mRem/y, with levels being as high as 1750 mRem/y near points of public access to piles. Some possible solutions to the problem are discussed

  1. Tree growth studies on uranium mill tailings

    International Nuclear Information System (INIS)

    Murray, D.R.; Turcotte, M.

    1982-01-01

    Coniferous trees planted in 1974 and deciduous species that have volunteered since 1970 on uranium mill tailings that had been stabilized to varying degrees using limestone and vegetation were evaluated. Their survival and growth rates were compared with those from other investigations. Competition for light appears to be a major contributor to mortality. Differences in soil moisture conditions under a tree stand as compared to those under a grass sward are potentially significant enough to affect the tailings hydrology and effluent contamination. Recommendations include planting seeds of deciduous species or deciduous and coniferous seedlings on strips of freshly disturbed tailings. The disturbed strips would provide reduced competition for the initial year and assist in tree survival. The planting of block stands of coniferous or deciduous trees would be useful for evaluating the hydrological impact of the trees as compared to the present grass sward

  2. Optimization of uranium mill tailings disposal practices

    International Nuclear Information System (INIS)

    Richardson, Allan C.B.; Rowe, William D.

    1984-01-01

    So far as we have been to discern, no uranium mill tailings pile has yet been properly stabilized for long-term disposal. And although considerable effort is now being directed at developing practical solutions and at establishing standards for permanent disposal, the difficulties in application are diverse. They arise from the variety of environments in which milling is conducted, the significant costs associated with disposing of the large volumes of materials involved, the diverse nature of the hazards to be protected against, and uncertainties in both performance of controls and in how to determine societal responsibilities for management of the long term hazards to human populations from uranium tailings. There are 24 uranium tailings piles in the United States which no longer have responsible owners, and must now be disposed of by the U.S. Government in order to protect public health

  3. Field evaporation test of uranium tailings solution

    International Nuclear Information System (INIS)

    Chandler, B.L.; Shepard, T.A.; Stewart, T.A.

    1985-01-01

    A field experiment was performed to observe the effect on evaporation rate of a uranium tailings impoundment pond water as salt concentration of the water increased. The duration of the experiment was long enough to cause maximum salt concentration of the water to be attained. The solution used in the experiment was tailings pond water from an inactive uranium tailings disposal site in the initial stages of reclamation. The solution was not neutralized. The initial pH was about 1.0 decreasing to a salt gel at the end of the test. The results of the field experiment show a gradual and slight decrease in evaporation efficiency. This resulted as salt concentrations increased and verified the practical effectiveness of evaporation as a water removal method. In addition, the physical and chemical nature of the residual salts suggest that no long-term stability problem would likely result due to their presence in the impoundment during or after reclamation

  4. Orphan Stars Found in Long Galaxy Tail

    Science.gov (United States)

    2007-09-01

    Astronomers have found evidence that stars have been forming in a long tail of gas that extends well outside its parent galaxy. This discovery suggests that such "orphan" stars may be much more prevalent than previously thought. The comet-like tail was observed in X-ray light with NASA's Chandra X-ray Observatory and in optical light with the Southern Astrophysical Research (SOAR) telescope in Chile. The feature extends for more than 200,000 light years and was created as gas was stripped from a galaxy called ESO 137-001 that is plunging toward the center of Abell 3627, a giant cluster of galaxies. "This is one of the longest tails like this we have ever seen," said Ming Sun of Michigan State University, who led the study. "And, it turns out that this is a giant wake of creation, not of destruction." Chandra X-ray Image of ESO 137-001 and Tail in Abell 3627 Chandra X-ray Image of ESO 137-001 and Tail in Abell 3627 The observations indicate that the gas in the tail has formed millions of stars. Because the large amounts of gas and dust needed to form stars are typically found only within galaxies, astronomers have previously thought it unlikely that large numbers of stars would form outside a galaxy. "This isn't the first time that stars have been seen to form between galaxies," said team member Megan Donahue, also of MSU. "But the number of stars forming here is unprecedented." The evidence for star formation in this tail includes 29 regions of ionized hydrogen glowing in optical light, thought to be from newly formed stars. These regions are all downstream of the galaxy, located in or near the tail. Two Chandra X-ray sources are near these regions, another indication of star formation activity. The researchers believe the orphan stars formed within the last 10 million years or so. The stars in the tail of this fast-moving galaxy, which is some 220 million light years away, would be much more isolated than the vast majority of stars in galaxies. H-alpha Image of

  5. Effect of desliming of sulphide-rich mill tailings on the long-term strength of cemented paste backfill.

    Science.gov (United States)

    Ercikdi, Bayram; Baki, Hakan; İzki, Muhammet

    2013-01-30

    This paper presents the effect of desliming on the short- and long-term strength, stability and rheological properties of cemented paste backfill (CPB) produced from two different mill tailings. A 28-day unconfined compressive strength (UCS) of ≥1.0 MPa and the maintenance of stability over 224 days of curing were selected as the design criteria for the evaluation of paste backfill performance. Desliming induced some changes in the physical, chemical, mineralogical and rheological properties of the tailings. CPB mixture of the deslimed tailings achieved the required consistency at a lower water to cement ratio. The short-term UCSs of CPB samples of the deslimed tailings were found to be 30-100% higher than those samples of the reference tailings at all the binder dosages and curing times. CPB samples of the deslimed tailings achieved the long-term stability at relatively low binder dosages (e.g. 5 wt% c.f. ≥6.1% for the reference tailings). It was also estimated that desliming could allow a 13.4-23.1% reduction in the binder consumption depending apparently on the inherent characteristics of the tailings. Over the curing period, generation of sulphate and acid by the oxidation of pyrite present in the tailings was also monitored to correlate with the strength losses observed in the long term. Scanning electron microscope (SEM) and Mercury Intrusion Porosimetry (MIP) analyses provided an insight into the microstructure of CPB and the formation of secondary mineral phases (i.e. gypsum) confirming the beneficial effect of desliming. These findings suggest that desliming can be suitably exploited for CPB of sulphide-rich mill tailings to improve the strength and stability particularly in the long term and to reduce binder consumption. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Geochemical and mineralogical characterization of a neutral, low-sulfide/high-carbonate tailings impoundment, Markušovce, eastern Slovakia.

    Science.gov (United States)

    Hiller, Edgar; Petrák, Marián; Tóth, Roman; Lalinská-Voleková, Bronislava; Jurkovič, L'ubomír; Kučerová, Gabriela; Radková, Anežka; Sottník, Peter; Vozár, Jaroslav

    2013-11-01

    Tailings deposits generated from mining activities represent a potential risk for the aquatic environment through the release of potentially toxic metals and metalloids occurring in a variety of minerals present in the tailings. Physicochemical and mineralogical characteristics of tailings such as total concentrations of chemical elements, pH, ratio of acid-producing to acid-neutralizing minerals, and primary and secondary mineral phases are very important factors that control the actual release of potentially toxic metals and metalloids from the tailings to the environment. The aims of this study are the determination of geochemical and mineralogical characteristics of tailings deposited in voluminous impoundment situated near the village of Markušovce (eastern Slovakia) and identification of the processes controlling the mobility of selected toxic metals (Cu, Hg) and metalloids (As, Sb). The studied tailings have unique features in comparison with the other tailings investigated previously because of the specific mineral assemblage primarily consisting of barite, siderite, quartz, and minor sulfides. To meet the aims, samples of the tailings were collected from 3 boreholes and 15 excavated pits and subjected to bulk geochemical analyses (i.e., determination of chemical composition, pH, Eh, acid generation, and neutralization potentials) combined with detailed mineralogical characterization using optical microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMPA), and micro-X-ray diffraction (μ-XRD). Additionally, the geochemical and mineralogical factors controlling the transfer of potentially toxic elements from tailings to waters were also determined using short-term batch test (European norm EN 12457), sampling of drainage waters and speciation-equilibrium calculations performed with PHREEQC. The tailings mineral assemblage consists of siderite, barite, quartz, and dolomite. Sulfide minerals constitute only a minor proportion of the tailings

  7. International experience in tailings pond remediation

    International Nuclear Information System (INIS)

    Robertson, A.MacG.

    2001-01-01

    Tailings pond remediation is required primarily on mine closure. While mining is an ancient industry, requirement for mine facility remediation is a comparatively new development. Requirement for remediation has come about partly as a result of mans awareness of the environmental impacts of mining and his desire to minimize this, partly, as a result of the ever-increasing scale and production rates of tailings generation and the resulting increased environmental impacts and safety risks. The paper starts with a review of the evolution of mans intolerance of environmental impacts from tailings production and the assignment of liability to remediate such impacts. Many of the tailings ponds currently undergoing remediation were designed and constructed using methods and technology that would be considered inappropriate for new impoundments being designed and developed today. The paper reviews the history of tailings impoundment design and construction practice and the resulting inherent deficiencies that must be remediated. Current practices and future trends in tailings pond remediation are reviewed. The evolution of regulatory requirements is not only in terms of technical and safety criteria, but also in terms of financial and political risk. Perhaps the most substantive driver of risk management is today the requirement for corporate governance at mining company board level and oversight of new project development in the underdeveloped countries by the large financial institutions responsible for funding projects. Embarrassment in the public eye and punishment in the stock markets for poor environmental and safety performance is driving the need for efficient and effective risk management of potential impacts and the remediation to avoid these. A basis for practical risk management is described. (orig.)

  8. International experience in tailings pond remediation

    Energy Technology Data Exchange (ETDEWEB)

    MacG. Robertson, A. [Robertson GeoConsultants Ltd., Vancouver (Canada)

    2001-07-01

    Tailings pond remediation is required primarily on mine closure. While mining is an ancient industry, requirement for mine facility remediation is a comparatively new development. Requirement for remediation has come about partly as a result of mans awareness of the environmental impacts of mining and his desire to minimize this, partly, as a result of the ever-increasing scale and production rates of tailings generation and the resulting increased environmental impacts and safety risks. The paper starts with a review of the evolution of mans intolerance of environmental impacts from tailings production and the assignment of liability to remediate such impacts. Many of the tailings ponds currently undergoing remediation were designed and constructed using methods and technology that would be considered inappropriate for new impoundments being designed and developed today. The paper reviews the history of tailings impoundment design and construction practice and the resulting inherent deficiencies that must be remediated. Current practices and future trends in tailings pond remediation are reviewed. The evolution of regulatory requirements is not only in terms of technical and safety criteria, but also in terms of financial and political risk. Perhaps the most substantive driver of risk management is today the requirement for corporate governance at mining company board level and oversight of new project development in the underdeveloped countries by the large financial institutions responsible for funding projects. Embarrassment in the public eye and punishment in the stock markets for poor environmental and safety performance is driving the need for efficient and effective risk management of potential impacts and the remediation to avoid these. A basis for practical risk management is described. (orig.)

  9. Proceedings of the 2. international oil sands tailings conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    The tailings produced by oil sands extraction processes pose significant threats to the surrounding environment in addition to releasing greenhouse gases (GHGs) into the atmosphere. Recent directives have been established to reduce the amount of tailings produced at oil sands operations, and to ensure that tailings ponds are reclaimed in the most effective manner. This conference provided a forum for researchers and industry experts to discuss issues related to the management and reclamation of oil sands tailings. New technologies for dewatering tailings ponds were presented, and methods of analyzing the chemical properties of tailings were reviewed. The conference was divided into the following 7 sessions: (1) tailings properties, (2) tailings dewatering, (3) new concepts, (4) water and chemistry, (5) soft tailings stabilization and reclamation, (6) water treatment, and (7) new concepts 2. The conference featured 44 presentations, all of which have been catalogued separately for inclusion in this database. tabs., figs.

  10. Reclamation and closure of an oil sands tailings facility

    Energy Technology Data Exchange (ETDEWEB)

    Sobkowicz, J. [Thurber Engineering Ltd., Calgary, AB (Canada); Morgenstern, N. [Alberta Univ., Edmonton, AB (Canada)

    2010-07-01

    This PowerPoint presentation discussed methods of ensuring the successful reclamation of oil sands tailings facilities. Tailings should be reclaimed as mining proceeds in order to avoid an excessive accumulation of fluid fine tailings (FFT). The volume of mature fine tailings (MFT) in ponds should be limited in order to ensure effective tailings management. The reclaimed landforms should have good geotechnical stability and be comprised of self-sustaining native vegetation. Strength is needed to allow for timely capping and initial reclamation, and stiffness is required to minimize future settlement and to allow for the construction of a closure landscape. Reclamation strategies were presented for fines-dominated tailings; sand-depleted tailings; and sand-dominated tailings. Energy Resources Conservation Board (ERCB) criteria for tailings reclamation were discussed, and various monitoring and performance assessment strategies were presented. tabs., figs.

  11. A guide to the management of tailings facilities

    International Nuclear Information System (INIS)

    Bedard, C.; Ferguson, K.; Gladwin, D.; Lang, D.; Maltby, J.; McCann, M.; Poirier, P.; Schwenger, R.; Vezina, S.; West, S.; Duval, J.; Gardiner, E.; Jansons, K.; Lewis, B.; Matthews, J.; Mchaina, D.; Puro, M.; Siwik, R.; Welch, D.

    1998-01-01

    The 'Guide to the Management of Tailings Facilities' has been developed by the Mining Association of Canada in an effort to provide guidance to its member companies on sound practices for the safe and environmentally responsible management of tailings facilities. The guide is a reference tool to help companies ensure that they are managing their tailings facilities responsibly, integrating environmental and safety considerations in a consistent manner, with continuous improvement in the operation of tailings facilities. The key to managing tailings responsibly is consistent application of engineering capabilities through the full life cycle. The guide provides a basis for the development of customized tailings management systems to address specific needs at individual operations, and deals with environmental impacts, mill tailing characteristics, tailings facility studies and plans, dam and related structure design, and control and monitoring. Aspects relating to tailings facility siting, design, construction, operation, decommissioning and closure are also fully treated. 1 tab., 3 figs

  12. Long term aspects of uranium tailings management

    International Nuclear Information System (INIS)

    Bragg, K.

    1980-05-01

    This paper sets out the background issues which lead to the development of interim close-out criteria for uranium mill tailings. It places the current state-of-the-art for tailings management into both a national and international perspective and shows why such interim criteria are needed now. There are seven specific criteria proposed dealing with the need to have: passive barriers, limits on surface water recharge, durable systems, long term performance guarantees, limits to access, controls on water and airborne releases and finally to have a knowledge of exposure pathways. This paper is intended to serve as a focus for subsequent discussions with all concerned parties. (auth)

  13. Dynamics of Histone Tails within Chromatin

    Science.gov (United States)

    Bernier, Morgan; North, Justin; Page, Michael; Jaroniec, Christopher; Hammel, Christopher; Poirier, Michael

    2012-02-01

    Genetic information in humans is encoded within DNA molecules that is wrapped around histone octamer proteins and compacted into a highly conserved structural polymer, chromatin. The physical and material properties of chromatin appear to influence gene expression by altering the accessibility of proteins to the DNA. The tails of the histones are flexible domains that are thought to play a role in regulating DNA accessibility and compaction; however the molecular mechanisms for these phenomena are not understood. I will present CW-EPR studies on site directed spin labeled nucleosomes that probe the structure and dynamics of these histone tails within nucleosomes.

  14. Containment systems for uranium-mill tailings

    International Nuclear Information System (INIS)

    Hartley, J.N.; Buelt, J.L.

    1982-11-01

    Cover and liner systems for uranium mill tailings in the United States must satisfy stringent requirements regarding long-term stability, radon control, and radionuclide and hazardous chemical migration. The cover and liner technology discussed in this paper involves: (1) single and multilayer earthen cover systems; (2) asphalt emulsion radon barrier systems; and (3) asphalt, clay, and synthetic liner systems. These systems have been field tested at the Grand Junction, Colorado, tailings pile, where they have been shown to effectively reduce radon releases and radionuclide and chemical migration

  15. Trapping saturation of the bump-on-tail instability and electrostatic harmonic excitation in Earth's foreshock

    International Nuclear Information System (INIS)

    Klimas, A.J.

    1990-01-01

    Trapping saturation of the bump-on-tail instability is discussed using electron plasma Vlasov simulation results. The role of electrostatic harmonic excitation is considered in detail and shown to play a decisive role in the saturation of the instability. An extensive discussion of the simulation results is given to show that the results are not significantly limited by the finite number of Fourier modes used nor by the discrete distribution of those modes in wave number. It is argued that in the leading edge of Earth's electron foreshock a narrow wave number band of unstable field modes leads to trapping saturation of the bump-on-tail instability while simultaneously exciting electrostatic plasma waves at harmonics of the plasma frequency in simialr narrow bands of shorter wavelengths. The argument is based (1) on the observations of Lacombe et al. (1985), who found intense plasma waves at the leading edge of the foreshock with a spectral distribution sufficiently narrow to trap particles in resonance with the waves, and (2) on numerical simulations of the foreshock electron plasma which indicate that trapping saturation of the bump-on-tail instability leads to phase space vortex formation with consequent excitation of electrostatic harmonics. Thus it is suggested that observations of electrostatic harmonics in the leading edge of the foreshock would strongly implicate trapping as the saturation mechanism for the bump-on-tail instability in that region

  16. The long-term environmental impacts of the Mount Polley mine tailings spill, British Columbia, Canada

    Science.gov (United States)

    Byrne, Patrick; Hudson-Edwards, Karen; Macklin, Mark; Brewer, Paul; Bird, Graham; Williams, Richard

    2015-04-01

    On the 4th August 2014 a tailings impoundment failure at the Mount Polley gold and copper mine in British Columbia, Canada, released approximately 25 million m3 of solid and liquid waste into Hazeltine Creek, Quesnel Lake and Polley Lake. The sheer volume of the tailings released caused Haseltine Creek channel to expand from 2m to over 25m in width and Polley Lake water level to rise by 1.7m. The spill also removed trees in a 900 km2 corridor either side of Hazeltine Creek. Local residents and government officials have expressed serious concerns regarding the potential long-term effects on regional biodiversity, water security and to the livelihoods of First Nation communities. Among impoundment failures, the Mount Polley disaster is unique in that the solid tailings contain an unusual mixture of metal contaminants (arsenic, copper, gold, manganese, nickel, lead, vanadium). As particulate matter is the principal carrier of metal contaminants, the spilled tailings may reside in the regional soils and sediments for 1000s of years serving as a secondary source of pollution. The environmental risk posed by the spilled tailings is compounded by the location of the spill in a mountainous forested catchment, affected by severe winters with prominent spring snow melts that have the potential to remobilise very large quantities of spilled tailings. No data currently exist on the short- to long-term behaviour of these tailings in soils and sediments and the effects of the clean-up operations on their behaviour in this type of river environment. In this study, we adopt a multidisciplinary approach to determine the environmental and geomorphological impacts of the tailings spill. We have two specific objectives. (1) The physicochemical speciation and geochemical stability of spilled tailings will be characterised in surface and hyporheic sediments using bulk chemistry, mineralogical (XRD and SEM) and speciation methods (sequential extractions, electron microprobe analysis, XAS

  17. TIDAL TAILS OF MINOR MERGERS: STAR FORMATION EFFICIENCY IN THE WESTERN TAIL OF NGC 2782

    Energy Technology Data Exchange (ETDEWEB)

    Knierman, Karen; Scowen, Paul; Jansen, Rolf A. [School of Earth and Space Exploration, Arizona State University, 550 East Tyler Mall, Room PSF-686 (P.O. Box 871404), Tempe, AZ 85287-1404 (United States); Knezek, Patricia M. [WIYN Consortium, Inc., 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Wehner, Elizabeth, E-mail: karen.knierman@asu.edu, E-mail: paul.scowen@asu.edu, E-mail: rolf.jansen@asu.edu, E-mail: pknezek@noao.edu, E-mail: ewehner@haverford.edu [Department of Astronomy, Haverford College, Haverford, PA 19041 (United States)

    2012-04-10

    While major mergers and their tidal debris are well studied, they are less common than minor mergers (mass ratios {approx}< 0.3). The peculiar spiral NGC 2782 is the result of a merger between two disk galaxies with a mass ratio of {approx}4: 1 occurring {approx}200 Myr ago. This merger produced a molecular and H I-rich, optically bright eastern tail and an H I-rich, optically faint western tail. Non-detection of CO in the western tail by Braine et al. suggested that star formation had not yet begun to occur in that tidal tail. However, deep H{alpha} narrowband images show evidence of recent star formation in the western tail. Across the entire western tail, we find the global star formation rate per unit area ({Sigma}{sub SFR}) to be several orders of magnitude less than expected from the total gas density. Together with extended FUV+NUV emission from Galaxy Evolution Explorer along the tail, this indicates a low global star formation efficiency in the tidal tail producing lower mass star clusters. The H II region that we observed has a local (few-kiloparsec scale) {Sigma}{sub SFR} from H{alpha} that is less than that expected from the total gas density, which is consistent with other observations of tidal debris. The star formation efficiency of this H II region inferred from the total gas density is low, but normal when inferred from the molecular gas density. These results suggest the presence of a very small, locally dense region in the western tail of NGC 2782 or of a low-metallicity and/or low-pressure star-forming region.

  18. Recovery of iron from cyanide tailings with reduction roasting–water leaching followed by magnetic separation

    International Nuclear Information System (INIS)

    Zhang, Yali; Li, Huaimei; Yu, Xianjin

    2012-01-01

    Highlights: ► Using reduction roasting–water leaching–magnetic separation method, the recovery of iron from cyanide tailings was optimized. ► The recovery of iron was highly depended on the water-leaching process after reduction roasting. ► The results suggest that the method can be effectively used for iron recovery, and the grade of magnetic concentrate and recovery rate can reach 59.11% and 75.12%, respectively. - Abstract: Cyanide tailing is a kind of solid waste produced in the process of gold extraction from gold ore. In this paper, recovery of iron from cyanide tailings was studied with reduction roasting–water leaching process followed by magnetic separation. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery of iron were chiefly introduced. Systematic studies indicate that the high recovery rate and grade of magnetic concentrate of iron can be achieved under the following conditions: weight ratios of cyanide tailings/activated carbon/sodium carbonate/sodium sulfate, 100:10:3:10; temperature, 50 °C; time, 60 min at the reduction roasting stage; the liquid to solid ratio is 15:1 (ml/g), leaching at 60 °C for 5 min and stirring speed at 20 r/min at water-leaching; exciting current is 2 A at magnetic separation. The iron grade of magnetic concentrate was 59.11% and the recovery ratio was 75.12%. The mineralography of cyanide tailings, roasted product, water-leached sample, magnetic concentrate and magnetic tailings were studied by X-ray powder diffraction (XRD) technique. The microstructures of above products except magnetic tailings were also analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) to help understand the mechanism.

  19. Lateral movements of a massive tail influence gecko locomotion: an integrative study comparing tail restriction and autotomy.

    Science.gov (United States)

    Jagnandan, Kevin; Higham, Timothy E

    2017-09-07

    Tails are an intricate component of the locomotor system for many vertebrates. Leopard geckos (Eublepharis macularius) possess a large tail that is laterally undulated during steady locomotion. However, the tail is readily shed via autotomy, resulting in the loss of tail function, loss in body mass, and a cranial shift in the center of mass. To elucidate the function of tail undulations, we investigated changes in limb kinematics after manipulating the tail artificially by restricting tail undulations and naturally by removing the tail via autotomy. Restricting tail undulations resulted in kinematic adjustments similar to those that occur following tail autotomy, characterized by more flexed hind limb joints. These data suggest that effects of autotomy on locomotion may be linked to the loss of tail movements rather than the loss of mass or a shift in center of mass. We also provide empirical support for the link between lateral tail undulations and step length through the rotation of the pelvic girdle and retraction of the femur. Restriction and autotomy of the tail limits pelvic rotation, which reduces femur retraction and decreases step length. Our findings demonstrate a functional role for tail undulations in geckos, which likely applies to other terrestrial vertebrates.

  20. A nonluminescent and highly virulent Vibrio harveyi strain is associated with "bacterial white tail disease" of Litopenaeus vannamei shrimp.

    Directory of Open Access Journals (Sweden)

    Junfang Zhou

    Full Text Available Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by "white tail" and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905 was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN, white tail disease (WTD or penaeid white tail disease (PWTD. To differentiate from such diseases as with a sign of "white tail" but of non-bacterial origin, the present disease was named as "bacterial white tail disease (BWTD". Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system.

  1. Adaptation and detoxification mechanisms of Vetiver grass (Chrysopogon zizanioides) growing on gold mine tailings.

    Science.gov (United States)

    Melato, F A; Mokgalaka, N S; McCrindle, R I

    2016-01-01

    Vetiver grass (Chrysopogon zizanioides) was investigated for its potential use in the rehabilitation of gold mine tailings, its ability to extract and accumulate toxic metals from the tailings and its metal tolerant strategies. Vetiver grass was grown on gold mine tailings soil, in a hothouse, and monitored for sixteen weeks. The mine tailings were highly acidic and had high electrical conductivity. Vetiver grass was able to grow and adapt well on gold mine tailings. The results showed that Vetiver grass accumulated large amounts of metals in the roots and restricted their translocation to the shoots. This was confirmed by the bioconcentration factor of Zn, Cu, and Ni of >1 and the translocation factor of <1 for all the metals. This study revealed the defense mechanisms employed by Vetiver grass against metal stress that include: chelation of toxic metals by phenolics, glutathione S-tranferase, and low molecular weight thiols; sequestration and accumulation of metals within the cell wall that was revealed by the scanning electron microscopy that showed closure of stomata and thickened cell wall and was confirmed by high content of cell wall bound phenolics. Metal induced reactive oxygen species are reduced or eliminated by catalase, superoxide dismutase and peroxidase dismutase.

  2. Mine Waste Technology Program Electrochemical Tailings Cover

    Science.gov (United States)

    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 40, Electrochemical Tailings Cover, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. Department of Energy (DOE). MSE Technology A...

  3. Functional morphology of the aardvark tail.

    Science.gov (United States)

    Endo, H; Mori, K; Koyabu, D; Kawada, S; Komiya, T; Itou, T; Koie, H; Kitagawa, M; Sakai, T

    2013-04-01

    The musculoskeletal system of the aardvark (Orycteropus afer) tail was morphologically examined in two adult specimens. The tail musculature comprised three muscular groups, viz. a dorsal sacrocaudal system that consisted of the irregularly oriented Musculus sacrocaudalis dorsalis medialis and M. sacrocaudalis dorsalis lateralis, a lateral inter-vertebral connecting system, and a ventral sacrocaudal system characterized by the thick M. sacrocaudalis ventralis lateralis and M. sacrocaudalis ventralis medialis. Both the dorsal and ventral systems possessed large tendon groups that strengthened the tail structure. Computed tomography (CT) examination showed the presence of large but homogeneous cartilaginous inter-vertebral discs, whereas V-shaped bones were situated at the ventral aspect of the caudal vertebrae at the level of the inter-vertebral discs. CT visualization of the tendons and V-shaped bones in various tail positions suggested that these structures contribute to the tunnel digging action by bearing the trunk weight and lending force when the aardvark are displacing the soil by means of the forelimbs. © 2012 Blackwell Verlag GmbH.

  4. Electrokinetic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrián; Ottosen, Lisbeth M.

    2007-01-01

    in sulphuric acidified tailings) without bipolar electrodes to 42% when bipolar electrodes were implemented. Furthermore, the results showed that in this system sulphuric acid addition prior to remediation was better than citric acid addition. In addition, applying a too strong electric field (even...

  5. Geotechnical parameters and behaviour of uranium tailings

    International Nuclear Information System (INIS)

    Matyas, E.L.

    1984-01-01

    The results of laboratory and in situ testing and test blasting, the observations made on a test embankment, and a description of actual construction practice associated with engineering studies for the management of uranium mill tailings at Elliot Lake, Ontario are presented. Relative density values inferred from standard penetration tests and cone penetrometer tests are shown to be inconsistent with relative density values determined from maximum and minimum void ratios. Some of the data contradicts existing correlations. The compressibility of in situ saturated tailings is presented in graphical form in terms of void ratio, vertical effective stress, and mean grain size. Hydraulic conductivity is shown to range over many orders of magnitude, depending on the void ratio. The observations on an instrumental test embankment are used to explain the appropriate selection of geotechnical parameters that gave good agreement between back-calculated and observed settlements. One-dimensional consolidation theory was found to be valid for the embankment case. It is necessary to account for changes in soil properties that occur during the consolidation process in order to obtain a good fit between back-calculated and observed settlements. The successful use of tailings sand for embankment construction is described. On the basis of normalized standard penetration resistance values, it is concluded that localized zones of saturated tailings may be prone to liquefaction under predicted earthquake loadings

  6. The tail index of exchange rate returns

    NARCIS (Netherlands)

    C.G. Koedijk (Kees); M. Schafgans (Marcia); C.G. de Vries (Casper)

    1990-01-01

    textabstractIn the literature on the empirical distribution of foreign exchange rates there is now consensus that exchange rate yields are fat-tailed. Three problems, however, persist: (1) Which class of distribution functions is most appropriate? (2) Are the parameters of the distribution invariant

  7. DNA isolation from rat tail or ear

    NARCIS (Netherlands)

    Cuppen, E.

    2010-01-01

    This protocol describes a rapid procedure for isolating DNA from rat tail or ear punches. The simplest version of the protocol can be scaled for use in 96-well (deep-well) plates. The quality of the DNA is sufficient for any polymerase chain reaction (PCR)-based genotyping approach.

  8. Uranium mill tailings and risk estimation

    International Nuclear Information System (INIS)

    Marks, S.

    1984-04-01

    Work done in estimating projected health effects for persons exposed to mill tailings at vicinity properties is described. The effect of the reassessment of exposures at Hiroshima and Nagasaki on the risk estimates for gamma radiation is discussed. A presentation of current results in the epidemiological study of Hanford workers is included. 2 references

  9. Zone-tailed Hawk (Buteo albonotatus)

    Science.gov (United States)

    Scott H. Stoleson; Giancarlo Sadoti

    2010-01-01

    The Zone-tailed Hawk (Buteo albonotatus) might well be dubbed "the Great Pretender" because it so closely resembles the ubiquitous Turkey Vulture (Cathartes aura) in appearance and behavior as to be frequently mistaken for it. In the border regions where it lives, it may be confused as well with another "Mexican" raptor, the Common Black-Hawk (...

  10. Experiments on a Tail-wheel Shimmy

    Science.gov (United States)

    Harling, R; Dietz, O

    1954-01-01

    Model tests on the "running belt" and tests with a full-scale tail wheel were made on a rotating drum as well as on a runway in order to investigate the causes of the undesirable shimmy phenomena frequently occurring on airplane tail wheels, and the means of avoiding them. The small model (scale 1:10) permitted simulation of the mass, moments of inertia, and fuselage stiffness of the airplane and determination of their influence on the shimmy, whereas by means of the larger model with pneumatic tires (scale 1:2) more accurate investigations were made on the tail wheel itself. The results of drum and road tests show good agreement with one another and with model values. Detailed investigations were made regarding the dependence of the shimmy tendency on trail, rolling speed, load, size of tires, ground friction,and inclination of the swivel axis; furthermore, regarding the influence of devices with restoring effect on the tail wheel, and the friction damping required for prevention of shimmy. Finally observations from slow-motion pictures are reported and conclusions drawn concerning the influence of tire deformation.

  11. T-tail flutter analysis using Edge

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2011-11-01

    Full Text Available -tail. In reality, due to some a-symmetry in the grid, this was not quite achieved. The analyses consisted of a steady solution, followed by a prescribed, sine-squared, disturbance of 0.03 radians (corresponding to 10 mm lateral displacement at the fin top...

  12. A Case of True Human Tail

    Directory of Open Access Journals (Sweden)

    Amogh R Yadav

    2013-01-01

    Full Text Available Human tail are reported from various parts of the world. Although medically innocuous, these cause anxiety & social curiosity we report a case of 09 month old child with 8 cm stalked soft tissue lesion in the sacral region. MRI spine revealed a 2 mm intraspinal lipoma in lumbar region. The appendage was excised.

  13. The Harwell TAILS computer program user's manual

    International Nuclear Information System (INIS)

    Rouse, K.D.; Cooper, M.J.

    1980-11-01

    The Harwell TAILS computer program is a versatile program for crystal structure refinement through the analysis of neutron or X-ray diffraction data from single crystals or powders. The main features of the program are described and details are given of the data input and output specifications. (author)

  14. Mechanisms of tail resorption during anuran metamorphosis.

    Science.gov (United States)

    Nakai, Yuya; Nakajima, Keisuke; Yaoita, Yoshio

    2017-09-26

    Amphibian metamorphosis has historically attracted a good deal of scientific attention owing to its dramatic nature and easy observability. However, the genetic mechanisms of amphibian metamorphosis have not been thoroughly examined using modern techniques such as gene cloning, DNA sequencing, polymerase chain reaction or genomic editing. Here, we review the current state of knowledge regarding molecular mechanisms underlying tadpole tail resorption.

  15. Insights into Head-Tailed Viruses Infecting Extremely Halophilic Archaea

    Science.gov (United States)

    Pietilä, Maija K.; Laurinmäki, Pasi; Russell, Daniel A.; Ko, Ching-Chung; Jacobs-Sera, Deborah; Butcher, Sarah J.

    2013-01-01

    Extremophilic archaea, both hyperthermophiles and halophiles, dominate in habitats where rather harsh conditions are encountered. Like all other organisms, archaeal cells are susceptible to viral infections, and to date, about 100 archaeal viruses have been described. Among them, there are extraordinary virion morphologies as well as the common head-tailed viruses. Although approximately half of the isolated archaeal viruses belong to the latter group, no three-dimensional virion structures of these head-tailed viruses are available. Thus, rigorous comparisons with bacteriophages are not yet warranted. In the present study, we determined the genome sequences of two of such viruses of halophiles and solved their capsid structures by cryo-electron microscopy and three-dimensional image reconstruction. We show that these viruses are inactivated, yet remain intact, at low salinity and that their infectivity is regained when high salinity is restored. This enabled us to determine their three-dimensional capsid structures at low salinity to a ∼10-Å resolution. The genetic and structural data showed that both viruses belong to the same T-number class, but one of them has enlarged its capsid to accommodate a larger genome than typically associated with a T=7 capsid by inserting an additional protein into the capsid lattice. PMID:23283946

  16. Tail reconnection in the global magnetospheric context: Vlasiator first results

    Science.gov (United States)

    Palmroth, Minna; Hoilijoki, Sanni; Juusola, Liisa; Pulkkinen, Tuija I.; Hietala, Heli; Pfau-Kempf, Yann; Ganse, Urs; von Alfthan, Sebastian; Vainio, Rami; Hesse, Michael

    2017-11-01

    The key dynamics of the magnetotail have been researched for decades and have been associated with either three-dimensional (3-D) plasma instabilities and/or magnetic reconnection. We apply a global hybrid-Vlasov code, Vlasiator, to simulate reconnection self-consistently in the ion kinetic scales in the noon-midnight meridional plane, including both dayside and nightside reconnection regions within the same simulation box. Our simulation represents a numerical experiment, which turns off the 3-D instabilities but models ion-scale reconnection physically accurately in 2-D. We demonstrate that many known tail dynamics are present in the simulation without a full description of 3-D instabilities or without the detailed description of the electrons. While multiple reconnection sites can coexist in the plasma sheet, one reconnection point can start a global reconfiguration process, in which magnetic field lines become detached and a plasmoid is released. As the simulation run features temporally steady solar wind input, this global reconfiguration is not associated with sudden changes in the solar wind. Further, we show that lobe density variations originating from dayside reconnection may play an important role in stabilising tail reconnection.

  17. On the Hydrodynamics of Anomalocaris Tail Fins.

    Science.gov (United States)

    Sheppard, K A; Rival, D E; Caron, J-B

    2018-04-25

    Anomalocaris canadensis, a soft-bodied stem-group arthropod from the Burgess Shale, is considered the largest predator of the Cambrian period. Thanks to a series of lateral flexible lobes along its dorso-ventrally compressed body, it is generally regarded as an efficient swimmer, well-adapted to its predatory lifestyle. Previous theoretical hydrodynamic simulations have suggested a possible optimum in swimming performance when the lateral lobes performed as a single undulatory lateral fin, comparable to the pectoral fins in skates and rays. However, the role of the unusual fan-like tail of Anomalocaris has not been previously explored. Swimming efficiency and maneuverability deduced from direct hydrodynamic analysis are here studied in a towing tank facility using a three-vane physical model designed as an abstraction of the tail fin. Through direct force measurements, it was found that the model exhibited a region of steady-state lift and drag enhancement at angles of attack greater than 25° when compared to a triangular-shaped reference model. This would suggest that the resultant normal force on the tail fin of Anomalocaris made it well-suited for turning maneuvers, giving it the ability to turn quickly and through small radii of curvature. These results are consistent with an active predatory lifestyle, although detailed kinematic studies integrating the full organism, including the lateral lobes, would be required to test the effect of the tail fin on overall swimming performance. This study also highlights a possible example of evolutionary convergence between the tails of Anomalocaris and birds, which, in both cases, are well-adapted to efficient turning maneuvers.

  18. Histone H2A mobility is regulated by its tails and acetylation of core histone tails

    International Nuclear Information System (INIS)

    Higashi, Tsunehito; Matsunaga, Sachihiro; Isobe, Keisuke; Morimoto, Akihiro; Shimada, Tomoko; Kataoka, Shogo; Watanabe, Wataru; Uchiyama, Susumu; Itoh, Kazuyoshi; Fukui, Kiichi

    2007-01-01

    Histone tail domains play important roles in cellular processes, such as replication, transcription, and chromosome condensation. Histone H2A has one central and two tail domains, and their functions have mainly been studied from a biochemical perspective. In addition, analyses based on visualization have been employed for functional analysis of some chromatin proteins. In this study, we analyzed histone H2A mobility in vivo by two-photon FRAP, and elucidated that the histone H2A N- and C-terminal tails regulate its mobility. We found that histone H2A mobility was increased following treatment of host cells with a histone deacetylase inhibitor. Our results support a model in which core histone tails directly regulate transcription by interacting with nucleosome DNA via electrostatic interactions

  19. Tail-robust scheduling using Limited Processor Sharing.

    NARCIS (Netherlands)

    Nair, J.K.; Wierman, A.; Zwart, A.P.

    2010-01-01

    From a rare events perspective, scheduling disciplines that work well under light (exponential) tailed workload distributions do not perform well under heavy (power) tailed workload distributions, and vice versa, leading to fundamental problems in designing schedulers that are robust to

  20. ESTIMATION OF FILTRATION CAPACITY OF POSTFLOTATION TAILINGS EMBEDDED IN DAMS OF TAILINGS DEPOSITION SITES

    Directory of Open Access Journals (Sweden)

    Wojciech Tschuschke

    2015-10-01

    Full Text Available Construction of very big mine tailings deposition sites, such as postflotation tailings ponds, is a complicated engineering task, in which several technical and environmental problems need to be solved. Designing, construction and operation of such an object applying the monitoring method consists in the verification of design assumptions based on continuous observations. One of the primary tasks of monitoring while the deposition site is being filled with tailings is to control quality of the formed dam embankments, as the structural element of the object responsible for its stability. In order to use material selected from deposited tailings in the construction of dams it is necessary to define grain size and compaction criteria, which directly affect load bearing capacity and deformation of the structure. For this reason main control tests include the analyses of grain size distribution and physical properties of the material embedded in the dams. These data may also be used to estimate filtration capacity of the embankment. A lack of drainage, causing accumulation of water within the embankment, may potentially deteriorate stability conditions. This paper presents the use of empirical formulas, i.e. formulas typically applied to natural soils, to assess permeability coefficient of tailings. A simple empirical formula was also proposed for the estimation of permeability coefficient of tailings based on grain size and compaction parameters determined in routine quality tests of constructed dam embankments.

  1. Tail-assisted pitch control in lizards, robots and dinosaurs.

    Science.gov (United States)

    Libby, Thomas; Moore, Talia Y; Chang-Siu, Evan; Li, Deborah; Cohen, Daniel J; Jusufi, Ardian; Full, Robert J

    2012-01-04

    In 1969, a palaeontologist proposed that theropod dinosaurs used their tails as dynamic stabilizers during rapid or irregular movements, contributing to their depiction as active and agile predators. Since then the inertia of swinging appendages has been implicated in stabilizing human walking, aiding acrobatic manoeuvres by primates and rodents, and enabling cats to balance on branches. Recent studies on geckos suggest that active tail stabilization occurs during climbing, righting and gliding. By contrast, studies on the effect of lizard tail loss show evidence of a decrease, an increase or no change in performance. Application of a control-theoretic framework could advance our general understanding of inertial appendage use in locomotion. Here we report that lizards control the swing of their tails in a measured manner to redirect angular momentum from their bodies to their tails, stabilizing body attitude in the sagittal plane. We video-recorded Red-Headed Agama lizards (Agama agama) leaping towards a vertical surface by first vaulting onto an obstacle with variable traction to induce a range of perturbations in body angular momentum. To examine a known controlled tail response, we built a lizard-sized robot with an active tail that used sensory feedback to stabilize pitch as it drove off a ramp. Our dynamics model revealed that a body swinging its tail experienced less rotation than a body with a rigid tail, a passively compliant tail or no tail. To compare a range of tails, we calculated tail effectiveness as the amount of tailless body rotation a tail could stabilize. A model Velociraptor mongoliensis supported the initial tail stabilization hypothesis, showing as it did a greater tail effectiveness than the Agama lizards. Leaping lizards show that inertial control of body attitude can advance our understanding of appendage evolution and provide biological inspiration for the next generation of manoeuvrable search-and-rescue robots.

  2. A new procedure for deep sea mining tailings disposal

    NARCIS (Netherlands)

    Ma, W.; Schott, D.L.; Lodewijks, G.

    2017-01-01

    Deep sea mining tailings disposal is a new environmental challenge related to water pollution, mineral crust waste handling, and ocean biology. The objective of this paper is to propose a new tailings disposal procedure for the deep sea mining industry. Through comparisons of the tailings disposal

  3. Costs associated with tail autotomy in an ambush foraging lizard ...

    African Journals Online (AJOL)

    We induced tail autotomy in free ranging male Cordylus m. melanotus and measured potential shifts in behaviour (movements, foraging behaviour, time exposed and average distance to a potential refuge), and responses to an approaching human compared to marked individuals with complete tails. Tailed and tailless ...

  4. Spectrum of human tails: A report of six cases

    Directory of Open Access Journals (Sweden)

    Biswanath Mukhopadhyay

    2012-01-01

    Full Text Available Human tail is a curiosity, a cosmetic stigma and presents as an appendage in the lumbosacral region. Six patients of tail in the lumbosacral region are presented here to discuss the spectrum of presentation of human tails. The embryology, pathology and treatment of this entity are discussed along with a brief review of the literature.

  5. Uranium Mill Tailings Remedial Action Project surface project management plan

    International Nuclear Information System (INIS)

    1994-09-01

    This Project Management Plan describes the planning, systems, and organization that shall be used to manage the Uranium Mill Tailings Remedial Action Project (UMTRA). US DOE is authorized to stabilize and control surface tailings and ground water contamination at 24 inactive uranium processing sites and associated vicinity properties containing uranium mill tailings and related residual radioactive materials

  6. Leachability of metals from gold tailings by rainwater: an ...

    African Journals Online (AJOL)

    Mine leachates from gold tailings impoundments usually contain elevated concentrations of metals and sulphates that impact negatively on water quality. This study was aimed at assessing the leachability of such metals from tailings by rainwater. Oxidised and unoxidised tailings were leached experimentally and through ...

  7. How We Tend To Overestimate Powerlaw Tail Exponents

    OpenAIRE

    Nassim N. Taleb

    2012-01-01

    In the presence of a layer of metaprobabilities (from uncertainty concerning the parameters), the asymptotic tail exponent corresponds to the lowest possible tail exponent regardless of its probability. The problem explains "Black Swan" effects, i.e., why measurements tend to chronically underestimate tail contributions, rather than merely deliver imprecise but unbiased estimates.

  8. Microscale mineralogical characterization of As, Fe, and Ni in uranium mine tailings

    Science.gov (United States)

    Essilfie-Dughan, Joseph; Hendry, M. Jim; Warner, Jeff; Kotzer, Tom

    2012-11-01

    Uranium (U) ores can contain high concentrations of elements of concern (EOCs), such as arsenic (As) and nickel (Ni) present in sulfide and arsenide minerals. The U in these ores is often solubilized by adding H2SO4 to attain a pH ∼1 under oxic conditions. This process releases some EOCs from the primary minerals into solution. The barren raffinate (solution remaining after U extraction) is subsequently neutralized with Ca(OH)2 to a terminal pH of ∼10.5, resulting in a reduction in the aqueous concentrations of the EOCs. These neutralized raffinates are mixed with the non-reacted primary minerals and discharged as tailing into tailings management facilities (TMFs). To aid in the accurate characterization and quantification of the mineralogical controls on the concentrations of EOCs in the tailings porewater, their spatial distribution and speciation were studied at the micron scale in tailings samples collected from the Deilmann U Tailings Management Facility (DTMF), northern Saskatchewan, Canada. Backscattered electron images of the tailings samples generated using an electron microprobe show the presence of nodules (10-200 μm size) surrounded by bright rims. Wavelength dispersive spectrometric (WDS) and synchrotron-based micro-X-ray fluorescence (μ-XRF) elemental mapping show that the nodules are dominated by Ca and S (as gypsum) and the bright rims are dominated by Fe, As, and Ni. Micro-X-ray absorption near-edge structure (μ-XANES) spectra collected within and near the rims indicate that the Fe and Ni are present mainly in the +3 and +2 oxidation states, respectively; for As, the +5 oxidation state dominates but significant amounts of the +3 oxidation state are present in some areas. Linear combination fit analyses of the K-edges for the Fe, As, and Ni μ-XANES spectra to reference compounds suggest the Fe in the rims is present as ferrihydrite with As and Ni are adsorbed to it. Energy dispersive spectrometric (EDS) data indicate that isolated, highly

  9. Sub-stratum injection of fine tailings

    Energy Technology Data Exchange (ETDEWEB)

    Kesteren van, W.; Cornelisse, J.; Costello, M. [Deltares, Delft (Netherlands)

    2010-07-01

    This PowerPoint presentation discussed an experiment conducted to evaluate the sub-stratum injection of oil sands fine tailings. The hydraulic fracturing method was developed as a sub-surface dredging process for mining sand without removing the overburden. Pressure was used to transport the sand-water mixture, and the high pressures used in the process resulted in water losses through the clay-sand interface. The experiment was conducted with soft clay, compacted sand, and an injection feed. Results of the study showed that the injection method may be successful. However, further research is required to characterize the fracture energy of oil sands and the rheology of fine tailings. Horizontal hydraulic fracturing equations were presented. Tensile failures in clay and oil sands were discussed. Fractures were identified by deformation and discharge rates. Crack propagation methods were also studied. tabs., figs.

  10. Factors influencing radon attenuation by tailing covers

    International Nuclear Information System (INIS)

    Silker, W.B.; Rogers, V.C.

    1981-07-01

    The US NRC, in its Generic Environmental Impact Statement on uranium milling has specified that the radon flux escaping a uranium mill tailings pile will be reduced to pCi/m 2 s by application of covering layers of soils and clays. These covers present a radon diffusion barrier, which sufficiently increases the time required for radon passage from the tailings to the atmosphere to allow for decay of 222 Rn within the cover. The depth of cover necessary to reduce the escaping radon flux to the prescribed level is to be determined by calculation, and requires precise knowledge of the radon diffusion coefficient in the covering media. A Radon Attenuation Test Facility was developed to determine rates of radon diffusion through candidate cover materials. This paper describes this facility and its application for determining the influence of physical properties of the soil column on the radon diffusion coefficient

  11. HF heating of a plasma column at frequencies below the electron cyclotron frequency

    International Nuclear Information System (INIS)

    Datlov, J.; Kopecky, V.; Musil, J.; Zacek, F.; Novik, K.

    1978-02-01

    The dispersion of waves, excited by the helical structure in a plasma column and the heating of a tail of the electron distribution function is studied at frequencies below the electron plasma frequency and the electron cyclotron frequency. (author)

  12. Automated registration of tail bleeding in rats.

    Science.gov (United States)

    Johansen, Peter B; Henriksen, Lars; Andresen, Per R; Lauritzen, Brian; Jensen, Kåre L; Juhl, Trine N; Tranholm, Mikael

    2008-05-01

    An automated system for registration of tail bleeding in rats using a camera and a user-designed PC-based software program has been developed. The live and processed images are displayed on the screen and are exported together with a text file for later statistical processing of the data allowing calculation of e.g. number of bleeding episodes, bleeding times and bleeding areas. Proof-of-principle was achieved when the camera captured the blood stream after infusion of rat whole blood into saline. Suitability was assessed by recording of bleeding profiles in heparin-treated rats, demonstrating that the system was able to capture on/off bleedings and that the data transfer and analysis were conducted successfully. Then, bleeding profiles were visually recorded by two independent observers simultaneously with the automated recordings after tail transection in untreated rats. Linear relationships were found in the number of bleedings, demonstrating, however, a statistically significant difference in the recording of bleeding episodes between observers. Also, the bleeding time was longer for visual compared to automated recording. No correlation was found between blood loss and bleeding time in untreated rats, but in heparinized rats a correlation was suggested. Finally, the blood loss correlated with the automated recording of bleeding area. In conclusion, the automated system has proven suitable for replacing visual recordings of tail bleedings in rats. Inter-observer differences can be eliminated, monotonous repetitive work avoided, and a higher through-put of animals in less time achieved. The automated system will lead to an increased understanding of the nature of bleeding following tail transection in different rodent models.

  13. Monte Carlo-Based Tail Exponent Estimator

    Czech Academy of Sciences Publication Activity Database

    Baruník, Jozef; Vácha, Lukáš

    2010-01-01

    Roč. 2010, č. 6 (2010), s. 1-26 R&D Projects: GA ČR GA402/09/0965; GA ČR GD402/09/H045; GA ČR GP402/08/P207 Institutional research plan: CEZ:AV0Z10750506 Keywords : Hill estimator * α-stable distributions * tail exponent estimation Subject RIV: AH - Economics http://library.utia.cas.cz/separaty/2010/E/barunik-0342493.pdf

  14. Prelude to THEMIS tail conjunction study

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2007-05-01

    Full Text Available A close conjunction of several satellites (LANL, GOES, Polar, Geotail, and Cluster distributed from the geostationary altitude to about 16 RE downstream in the tail occurred during substorm activity as indicated by global auroral imaging and ground-based magnetometer data. This constellation of satellites resembles what is planned for the THEMIS (Time History of Events and Macroscopic Interactions during Substorms mission to resolve the substorm controversy on the location of the substorm expansion onset region. In this article, we show in detail the dipolarization and dynamic changes seen by these satellites associated with two onsets of substorm intensification activity. In particular, we find that dipolarization at ~16 RE downstream in the tail can occur with dawnward electric field and without plasma flow, just like some near-Earth dipolarization events reported previously. The spreading of substorm disturbances in the tail coupled with complementary ground observations indicates that the observed time sequence on the onsets of substorm disturbances favors initiation in the near-Earth region for this THEMIS-like conjunction.

  15. Forecast Combination under Heavy-Tailed Errors

    Directory of Open Access Journals (Sweden)

    Gang Cheng

    2015-11-01

    Full Text Available Forecast combination has been proven to be a very important technique to obtain accurate predictions for various applications in economics, finance, marketing and many other areas. In many applications, forecast errors exhibit heavy-tailed behaviors for various reasons. Unfortunately, to our knowledge, little has been done to obtain reliable forecast combinations for such situations. The familiar forecast combination methods, such as simple average, least squares regression or those based on the variance-covariance of the forecasts, may perform very poorly due to the fact that outliers tend to occur, and they make these methods have unstable weights, leading to un-robust forecasts. To address this problem, in this paper, we propose two nonparametric forecast combination methods. One is specially proposed for the situations in which the forecast errors are strongly believed to have heavy tails that can be modeled by a scaled Student’s t-distribution; the other is designed for relatively more general situations when there is a lack of strong or consistent evidence on the tail behaviors of the forecast errors due to a shortage of data and/or an evolving data-generating process. Adaptive risk bounds of both methods are developed. They show that the resulting combined forecasts yield near optimal mean forecast errors relative to the candidate forecasts. Simulations and a real example demonstrate their superior performance in that they indeed tend to have significantly smaller prediction errors than the previous combination methods in the presence of forecast outliers.

  16. Tailings management for the twenty-first century

    International Nuclear Information System (INIS)

    Frost, S.E.

    1996-01-01

    The evolution of tailings management at Saskatchewan uranium mines is traced from the fifties to the nineties. Some of the problems with past systems are discussed. The new tailings systems now being proposed for the new operations currently undergoing environmental assessment in Saskatchewan are examined in detail. These new systems represent a change in tailings management philosophy, from keeping tailings high and dry on the surface, to placement of tailings in a low-energy regime within the water table. There they are removed from the active surface environment, avoiding future erosion problems, with a reduced likelihood of suffering intrusion from future human or animal activities. (author). 16 refs., 5 figs

  17. Tailings dams from the perspective of conventional dam engineering

    International Nuclear Information System (INIS)

    Szymanski, M.B.

    1999-01-01

    A guideline intended for conventional dams such as hydroelectric, water supply, flood control, or irrigation is used sometimes for evaluating the safety of a tailings dam. Differences between tailings dams and conventional dams are often substantial and, as such, should not be overlooked when applying the techniques or safety requirements of conventional dam engineering to tailings dams. Having a dam safety evaluation program developed specifically for tailings dams is essential, if only to reduce the chance of potential errors or omissions that might occur when relying on conventional dam engineering practice. This is not to deny the merits of using the Canadian Dam Safety Association Guidelines (CDSA) and similar conventional dam guidelines for evaluating the safety of tailings dams. Rather it is intended as a warning, and as a rationale underlying basic requirement of tailings dam emgineering: specific experience in tailings dams is essential when applying conventional dam engineering practice. A discussion is included that focuses on the more remarkable tailings dam safety practics. It is not addressed to a technical publications intended for such dams, or significantly different so that the use of conventional dam engineering practice would not be appropriate. The CDSA Guidelines were recently revised to include tailings dams. But incorporating tailings dams into the 1999 revision of the CDSA Guidelines is a first step only - further revision is necessary with respect to tailings dams. 11 refs., 2 tabs

  18. Placement of radium/barium sludges in tailings areas

    International Nuclear Information System (INIS)

    Murphy, K.L.; Multamaki, G.E.

    1980-01-01

    Currently radium is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate the radium as radium/barium sulphate. The precipitate is allowed to settle in sedimentation basins prior to discharge of the effluent. The sedimentation basins are not suitable for final disposal of the sludge, and placement of the sludges in the tailings area has been proposed. The geochemical environment of fresh tailings areas was characterized as an acidic, oxidized surface zone underlain by an alkaline, reduced zone comprising the rest of the tailings. The quantity of sludge produced was estimated to be small relative to the quantity of tailings, and therefor a relatively small amount of radium would be added to the tailings disposal area by the addition of sludge. To confirm whether sludge addition affected radionuclide solubilization, laboratory leaching tests were conducted on slurries of acid leach tailings, and sludge-tailings mixtures. Radium in the (Ra,Ba)SO 4 sludge was at least as stable as radium in the tailings, and the sludge was able to absorb radium released from the tailings. The addition of sludge did not affect uranium and thorium solubilization. From these results it appears that the placement of sludge in tailings areas would not adversely affect the stability of radionuclides in the tailings or sludge. (auth)

  19. Polymer aids for settling and filtration of oil sands tailings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Energy Resources Conservation Board, Calgary, AB (Canada). Oil Sands Section; Xu, Z.; Masliyah, J.H. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2008-07-01

    Oil sand tailings are segregated into coarse and fine tailings. High volumes of toxic fluids and tailings are created in the process. Tailings ponds are an environmental risk with high operating and maintenance costs. Current commercial technologies uses chemical additions to create recycled water and composite tailings (CT). Researchers are now investigating centrifuged and dry mature fine tailings (MFT). Filtration processes with flocculants are used to separate the tailings into warm recycle water and dried cakes that can be used in reclamation processes. Studies are being conducted to find a polymer than can effectively flocculate and filter whole oil sands tailings. The filtration procedure uses pressure to produce released water. Polymers include magnafloc and Al-PAM polymer concentrations are used in slurry masses. Tests have been conducted to determine the settling rates of the polymers. The tests showed that Al-PAM filtered the tailings effectively. Paraffinic froth treatment tests have also been conducted to determine settling rates. A cake produced with froth treatment tailings of Al-PAM 400 ppm had a water content 42.5 wt per cent. The tests showed that while Magnafloc 1011 is a good settling aid, but a poor filtration addition. Al-PAM aided in both the flocculation and filtration processes. Higher Al-PAM dosages are needed for froth treatment tailings processes. It was concluded that dry cakes are produced with the addition of Al-PAM. tabs., figs.

  20. Asphalt emulsion sealing of uranium mill tailings. 1979 annual report

    International Nuclear Information System (INIS)

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

    1980-06-01

    Uranium mill tailings are a source of low-level radiation and radioactive materials that may be released into the environment. Stabilization or disposal of these tailings in a safe and environmentally sound way is necessary to minimize radon exhalation and other radioactive releases. One of the most promising concepts for stabilizing uranium tailings is being investigated at the Pacific Northwest Laboratory: the use of asphalt emulsion to contain radon and other potentially hazardous materials in uranium tailings. Results of these studies indicate that radon flux from uranium tailings can be reduced by greater than 99% by covering the tailings with an asphalt emulsion that is poured on or sprayed on (3.0 to 7.0 mm thick), or mixed with some of the tailings and compacted to form an admixture seal (2.5 to 15.2 cm) containing 18 wt % residual asphalt

  1. A Note on Upper Tail Behavior of Liouville Copulas

    Directory of Open Access Journals (Sweden)

    Lei Hua

    2016-11-01

    Full Text Available The family of Liouville copulas is defined as the survival copulas of multivariate Liouville distributions, and it covers the Archimedean copulas constructed by Williamson’s d-transform. Liouville copulas provide a very wide range of dependence ranging from positive to negative dependence in the upper tails, and they can be useful in modeling tail risks. In this article, we study the upper tail behavior of Liouville copulas through their upper tail orders. Tail orders of a more general scale mixture model that covers Liouville distributions is first derived, and then tail order functions and tail order density functions of Liouville copulas are derived. Concrete examples are given after the main results.

  2. Big picture thinking in oil sands tailings disposal

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, J. [Thurber Engineering Ltd., Calgary, AB (Canada)

    2010-07-01

    This PowerPoint presentation discussed methods of disposing oil sands tailings. Oil sands operators are currently challenged by a variety of legislative and environmental factors concerning the creation and disposal of oil sands tailings. The media has focused on the negative ecological impact of oil sands production, and technical issues are reducing the effect of some mitigation processes. Operators must learn to manage the interface between tailings production and removal, the environment, and public opinion. The successful management of oil sand tailings will include procedures designed to improve reclamation processes, understand environmental laws and regulations, and ensure that the cumulative impacts of tailings are mitigated. Geotechnical investigations, engineering designs and various auditing procedures can be used to develop tailings management plans. Environmental screening and impact assessments can be used to develop sustainable solutions. Public participation and environmental mediation is needed to integrate the public, environmental and technical tailings management strategies. Operators must ensure public accountability for all stakeholders. tabs., figs.

  3. Fat-tailed risk about climate change and climate policy

    International Nuclear Information System (INIS)

    Hwang, In Chang; Tol, Richard S.J.; Hofkes, Marjan W.

    2016-01-01

    This paper investigates the role of emissions control in welfare maximization under fat-tailed risk about climate change. We provide a classification of fat tails and discuss the effect of fat-tailed risk on climate policy. One of the main findings is that emissions control may prevent the “strong” tail-effect from arising, at least under some conditions such as bounded temperature increases, low risk aversion, low damage costs, and bounded utility function. More specifically, the fat-tailed risk with respect to a climate parameter does not necessarily lead to an unbounded carbon tax. In this case, the basic principle of cost-benefit analysis maintains its applicability. - Highlights: • A fat tail is classified and the tail effect on climate policy is discussed. • The optimal carbon tax is not necessarily unbounded. • The basic principle of cost-benefit analysis maintains its applicability. • This is a numerical confirmation of the recent theoretical research.

  4. Ecological aspects of microorganisms inhabiting uranium mill tailings

    Science.gov (United States)

    Miller, C.L.; Landa, E.R.; Updegraff, D.M.

    1987-01-01

    Numbers and types of microorganisms in uranium mill tailings were determined using culturing techniques. Arthrobacter were found to be the predominant microorganism inhabiting the sandy tailings, whereas Bacillus and fungi predominated in the slime tailings. Sulfate-reducing bacteria, capable of leaching radium, were isolated in low numbers from tailings samples but were isolated in significantly high numbers from topsoil in contact with the tailings. The results are placed in the context of the magnitude of uranium mill tailings in the United States, the hazards posed by the tailings, and how such hazards could be enhanced or diminished by microbial activities. Patterns in the composition of the microbial population are evaluated with respect to the ecological variables that influence microbial growth. ?? 1987 Springer-Verlag New York Inc.

  5. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger.

    Science.gov (United States)

    Déjeant, Adrien; Galoisy, Laurence; Roy, Régis; Calas, Georges; Boekhout, Flora; Phrommavanh, Vannapha; Descostes, Michael

    2016-03-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam--Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Chapter 2. The history of uranium tailings formation in the North of Tajikistan, their current condition. 2.4. Degmai uranium tailings

    International Nuclear Information System (INIS)

    Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.

    2012-01-01

    Present article is devoted to Degmai uranium tailings. The history of Degmai uranium tailings is presented. The current condition of uranium tailings is described. During the last 6-7 years, together with IAEA experts, monitoring is permanently carried out and the tailings influence on the environment is defined. Radiation and dosimetric investigation results from Degmai tailing' surface (June 2006) are considered.

  7. Taming the tailings : dead ducks notwithstanding, extensive research is underway to deal with oilsands tailings in a more efficient manner

    Energy Technology Data Exchange (ETDEWEB)

    Collison, M.

    2008-09-15

    Research is now being conducted to reduce the environmental impacts of oil sands tailing ponds. Alberta's oil sands region contains an estimated 60 km{sup 2} of tailings ponds, which serve as holding basins for recycled water as well as collection sites for materials used in reclamation activities. The ponds contain residual bitumen, production chemicals, and minerals. While some of the water in the ponds can be re-used, mature fine tailings must be contained behind dikes. Every barrel of bitumen produced by the industry results in the creation of 1.5 barrels of mature fine tailings. Natural Resources Canada's CANMET Energy Technology Centre is currently conducting a research program with the University of Alberta to reduce the amounts of tailings produced by the industry. Options for dry stackable tailings are being explored, as well as methods of using the tailings to enhance various oil sands processes. It is hoped that the dry, stackable tailings can be used to help reclaim and rebuild Boreal regions impacted by the oil sands industry. The program is gaining interest due to concerns that leakages from the tailings ponds may pollute aquifers and rivers in a region noted for its water shortages. Research teams are also investigating the use of flocculants to create heavy non-segregated tailings. Researchers are also examining methods of recovering hydrocarbons, titanium, and zircon from the tailings. 3 figs.

  8. Tail docking in pigs: a review on its short- and long-term consequences and effectiveness in preventing tail biting

    Directory of Open Access Journals (Sweden)

    Eleonora Nannoni

    2014-02-01

    Full Text Available In spite of European legislation attempting to limit this practice, tail docking is nowadays the only preventive measure against tail biting which is widely adopted by farmers. Docking consists in amputating, usually without anaesthesia or analgesia, the distal part of the tail, in order to reduce its attractiveness and to sensitize it, increasing avoidance behaviour in the bitten pig. Tail docking results in both acute and chronic effects on pig welfare, and its effectiveness in preventing tail biting is limited, since it reduces the symptoms of a behavioural disorder, but does not address the underlying causes. The aim of the present paper is to review the available literature on the effects of tail docking on swine welfare. Although from a practical standpoint the welfare risks arising from tail docking may appear to be negligible compared to those arising during and after tail biting outbreaks, it should be considered that, apart from acute physiological and behavioural responses, tail docking may also elicit long-term effects on weight gain, tail stump sensitivity and animal freedom to express their normal behaviour. Such chronic effects have been poorly investigated so far. Besides, studies evaluating the effectiveness of anaesthetics or analgesic treatments are often conflicting. Within this framework, further research is recommended in order to reduce the acute and chronic pain and discomfort experienced by the animals, until preventive measures (e.g., environmental enrichment, stocking densities are broadly adopted to prevent tail biting.

  9. Metal mobilization under alkaline conditions in ash-covered tailings.

    Science.gov (United States)

    Lu, Jinmei; Alakangas, Lena; Wanhainen, Christina

    2014-06-15

    The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Oil sands tailings technology : understanding the impact to reclamation

    Energy Technology Data Exchange (ETDEWEB)

    Mamer, M. [Suncor Energy Inc., Fort McMurray, AB (Canada)

    2010-07-01

    This paper discussed tailings management techniques at oil sands mines and their effects on reclamation schedules and outcomes. The layer of mature fine tailings (MFT) that forms in tailings ponds does not settle within a reasonable time frame, requiring more and larger tailings ponds for storing MFT. Consolidated tailings (CT) technology was developed to accelerate the consolidation of MFT, although the process nonetheless takes decades. CT is produced from mixing tailings sand, gypsum, and MFT to create a mixture that will consolidate more quickly and release water. However, CT production is tied to the extraction process, making it applicable only when the plant is operational, and a precise recipe and accurate injection are required for CT to work. In tailings reduction operations (TRO), a new approach to tailings management, MFT is mixed with a polymer flocculant, deposited in thin layers, and allowed to dry. TRO has a significant advantage over CT in that the latter takes up to 30 years to consolidate to a trafficable surface compared to weeks for TRO. TRO allows MFT to be consumed more quickly than it is produced, reducing need to build more tailings ponds, operates independent of plant operations, accelerates the reclamation time frame, and offers enhanced flexibility in final tailings placement sites. TRO also creates a dry landscape, to which well established reclamation techniques can be applied. Dried MFT is a new material type, and research is exploring optimum reclamation techniques. 2 figs.

  11. Flexible histone tails in a new mesoscopic oligonucleosome model.

    Science.gov (United States)

    Arya, Gaurav; Zhang, Qing; Schlick, Tamar

    2006-07-01

    We describe a new mesoscopic model of oligonucleosomes that incorporates flexible histone tails. The nucleosome cores are modeled using the discrete surface-charge optimization model, which treats the nucleosome as an electrostatic surface represented by hundreds of point charges; the linker DNAs are treated using a discrete elastic chain model; and the histone tails are modeled using a bead/chain hydrodynamic approach as chains of connected beads where each bead represents five protein residues. Appropriate charges and force fields are assigned to each histone chain so as to reproduce the electrostatic potential, structure, and dynamics of the corresponding atomistic histone tails at different salt conditions. The dynamics of resulting oligonucleosomes at different sizes and varying salt concentrations are simulated by Brownian dynamics with complete hydrodynamic interactions. The analyses demonstrate that the new mesoscopic model reproduces experimental results better than its predecessors, which modeled histone tails as rigid entities. In particular, our model with flexible histone tails: correctly accounts for salt-dependent conformational changes in the histone tails; yields the experimentally obtained values of histone-tail mediated core/core attraction energies; and considers the partial shielding of electrostatic repulsion between DNA linkers as a result of the spatial distribution of histone tails. These effects are crucial for regulating chromatin structure but are absent or improperly treated in models with rigid histone tails. The development of this model of oligonucleosomes thus opens new avenues for studying the role of histone tails and their variants in mediating gene expression through modulation of chromatin structure.

  12. A kinetic study of solar wind electrons

    International Nuclear Information System (INIS)

    Lie-Svendsen, Oeystein; Leer, Egil

    1996-01-01

    The evolution of the distribution function for a test population of electrons in an isothermal electron-proton corona has been studied using a Fokker-Planck description. The aim is to investigate whether a suprathermal tail forms due to the energy dependence of the Coulomb cross section. We find that a Maxwellian test population, injected into this background close to the coronal base with a temperature equal to that of the background electrons, maintains its shape throughout the transition from collision-dominated to collisionless flow. No significant suprathermal tail in the electron distribution function is seen in the outer corona

  13. Phytomining for Artisanal Gold Mine Tailings Management

    Directory of Open Access Journals (Sweden)

    Baiq Dewi Krisnayanti

    2016-08-01

    Full Text Available Mine tailings are generally disposed of by artisanal and small scale gold miners in poorly constructed containment areas and this leads to environmental risk. Gold phytomining could be a possible option for tailings management at artisanal and small-scale gold mining (ASGM locations where plants accumulate residual gold in their above ground biomass. The value of metal recovered from plants could offset some of the costs of environmental management. Getting gold into plants has been repeatedly demonstrated by many research groups; however, a simple working technology to get gold out of plants is less well described. A field experiment to assess the relevance of the technology to artisanal miners was conducted in Central Lombok, Indonesia between April and June 2015. Tobacco was planted in cyanidation tailings (1 mg/kg gold and grown for 2.5 months before the entire plot area was irrigated with NaCN to induce metal uptake. Biomass was then harvested (100 kg, air dried, and ashed by miners in equipment currently used to ash activated carbon at the end of a cyanide leach circuit. Borax and silver as a collector metal were added to the tobacco ash and smelted at high temperature to extract metals from the ash. The mass of the final bullion (39 g was greater than the mass of silver used as a collector (31 g, indicating recovery of metals from the biomass through the smelt process. The gold yield of this trial was low (1.2 mg/kg dry weight biomass concentration, indicating that considerable work must still be done to optimise valuable metal recovery by plants at the field scale. However, the described method to process the biomass was technically feasible, and represents a valid technique that artisanal and small-scale gold miners are willing to adopt if the economic case is good.

  14. Dwarf Galaxies Swimming in Tidal Tails

    Science.gov (United States)

    2005-01-01

    This false-color infrared image from NASA's Spitzer Space Telescope shows little 'dwarf galaxies' forming in the 'tails' of two larger galaxies that are colliding together. The big galaxies are at the center of the picture, while the dwarfs can be seen as red dots in the red streamers, or tidal tails. The two blue dots above the big galaxies are stars in the foreground. Galaxy mergers are common occurrences in the universe; for example, our own Milky Way galaxy will eventually smash into the nearby Andromeda galaxy. When two galaxies meet, they tend to rip each other apart, leaving a trail, called a tidal tail, of gas and dust in their wake. It is out of this galactic debris that new dwarf galaxies are born. The new Spitzer picture demonstrates that these particular dwarfs are actively forming stars. The red color indicates the presence of dust produced in star-forming regions, including organic molecules called polycyclic aromatic hydrocarbons. These carbon-containing molecules are also found on Earth, in car exhaust and on burnt toast, among other places. Here, the molecules are being heated up by the young stars, and, as a result, shine in infrared light. This image was taken by the infrared array camera on Spitzer. It is a 4-color composite of infrared light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). Starlight has been subtracted from the orange and red channels in order to enhance the dust features.

  15. Contemporary Pollution Due Old Uranium Tails

    International Nuclear Information System (INIS)

    Hadjamberdiev, I.

    2007-01-01

    The areas of our study are uranium mining areas (with tails and dumps) Min-Kush, Kadji-Sai, Mailuu-Suu. These areas situated in different parts of Tien-Shan region. We study the content (and correlations among): level of uranium in environment, immune function and level, level in human teeth. It has been found: content of uranium in river water under tails about 2,0x10-5 gm/litter, and high level in drinking water too 2,0-4,0. Drying grass and flowers uranium content was 0,04-0,51x10-5 gm/gm, most high content were in Tacniatherum crinitum and Atgilops triuncialis. Lams tissues contain 0,005-2,44 mg/g in Min-Kush, 0,03-0,107, in Mailuu-Suu, and 0,001-0,048 mg/g in Kadji-Sai. Human teeth uranium content (Mailuu-Suu): in milk-teeth 0,481x10-6 gm/gm, in former miners 0,7684x10-6 gm/gm. Inhabitants of the area, which not working in uranium industry have 0,6876x10-6 gm/gm. There was low level of immune function (lymphocytes, IgI globulin, etc) in all three regions (in child, in adults, in uranium-mining worked people). There is no doubt of the positive correlations of uranium pollution of water (by underground infiltration from tails) on one hand and, on the other hand - a) grass, b) lambs body, c) human teeth, d) human immune function. Levels of uranium in teeth strictly depend on time of mining contact. (author)

  16. Optimization in the decommissioning of uranium tailings

    International Nuclear Information System (INIS)

    1987-06-01

    This report examines in detail the problem of choosing the optimal decommissioning approach for uranium and mill tailings sites. Various decision methods are discussed and evaluated, and their application in similar decision problems are summarized. This report includes, by means of a demonstration, a step by step guide of how a number of selected techniques can be applied to a decommissioning problem. The strengths and weaknesses of various methods are highlighted. A decision system approach is recommended for its flexibility and incorporation of many of the strengths found in other decision methods

  17. Biogeochemistry of metalliferous mine tailings during phytostabilizatio

    Science.gov (United States)

    Chorover, J.; Root, R. A.; Hammond, C.; Wang, Y.; Maier, R. M.

    2015-12-01

    In the semi-arid southwest US, legacy mine tailings and the associated metal(loid) contaminants, are prone to wind dispersion and water erosion. Without remediation, tailings can remain barren for decades to centuries, providing a point source of toxic contamination. Successful mitigation of toxins (As, Pb) from fugitive dust is often limited to confinement and stabilization. Capping mine tailings with soil or gravel is an accepted, although expensive, strategy to reduce erosion. Revegetation via assisted direct planting (also known as phytostabilization) has the potential to be a cost-effective and self-sustaining alternative "green-technology" to expensive capping. The impact of phytostabilization, and requisite added organic carbon and irrigation on mechanisms of contaminant mobility is being investigated with concurrent highly-instrumented greenhouse mesocosms and in situ field studies using advanced microbiological tools and synchrotron x-ray based molecular probes. Composted treatments initially neutralized the near surface acid tailings (~2 to ~6.5). However, after 9 mo the mesocosms showed a gradual and eventual decrease back to pH 2. The exception was the root zone of Atriplex lentiformis, which buffered the acidic conditions for 12 months. Rhizosphere microbiota experienced a 5-log increase in the compost-amended compared to control greenhouse mesocosms. Weathering of the primary sulfidic mineral assemblage, indicated by the iron and sulfur speciation, was shown to control the mobility, speciation and bioavailability of both As and Pb via sequestration in (meta)stable neoformed jarosite phases as plumbojarosite and As(V) substituted for sulfate in hydronium jarosite, with important implications for human and environmental health risk management. We conclude that the disequilibrium imposed by phytostabilization results in an increase of heterotrophic biomass that is concurrent with a time series of geochemical transformations, which controls the species

  18. Tail-weighted dependence measures with limit being the tail dependence coefficient

    KAUST Repository

    Lee, David

    2017-12-02

    For bivariate continuous data, measures of monotonic dependence are based on the rank transformations of the two variables. For bivariate extreme value copulas, there is a family of estimators (Formula presented.), for (Formula presented.), of the extremal coefficient, based on a transform of the absolute difference of the α power of the ranks. In the case of general bivariate copulas, we obtain the probability limit (Formula presented.) of (Formula presented.) as the sample size goes to infinity and show that (i) (Formula presented.) for (Formula presented.) is a measure of central dependence with properties similar to Kendall\\'s tau and Spearman\\'s rank correlation, (ii) (Formula presented.) is a tail-weighted dependence measure for large α, and (iii) the limit as (Formula presented.) is the upper tail dependence coefficient. We obtain asymptotic properties for the rank-based measure (Formula presented.) and estimate tail dependence coefficients through extrapolation on (Formula presented.). A data example illustrates the use of the new dependence measures for tail inference.

  19. Tail-weighted dependence measures with limit being the tail dependence coefficient

    KAUST Repository

    Lee, David; Joe, Harry; Krupskii, Pavel

    2017-01-01

    For bivariate continuous data, measures of monotonic dependence are based on the rank transformations of the two variables. For bivariate extreme value copulas, there is a family of estimators (Formula presented.), for (Formula presented.), of the extremal coefficient, based on a transform of the absolute difference of the α power of the ranks. In the case of general bivariate copulas, we obtain the probability limit (Formula presented.) of (Formula presented.) as the sample size goes to infinity and show that (i) (Formula presented.) for (Formula presented.) is a measure of central dependence with properties similar to Kendall's tau and Spearman's rank correlation, (ii) (Formula presented.) is a tail-weighted dependence measure for large α, and (iii) the limit as (Formula presented.) is the upper tail dependence coefficient. We obtain asymptotic properties for the rank-based measure (Formula presented.) and estimate tail dependence coefficients through extrapolation on (Formula presented.). A data example illustrates the use of the new dependence measures for tail inference.

  20. Recent advancements in the geotechnical characterization of oil sands tailings

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, J. [Conetec, Richmond, BC (Canada)

    2010-07-01

    The technical aspects of soft oil sands tailings in-situ geotechnical site investigations were discussed. Geotechnical studies are conducted to determine containment structure stability as well as to determine volumetric and mass balances. The results of the studies are used in tailings management plans and construction activities. Flow penetrometers, field vane shear tests, and Gamma-CPTu tests are used in in-situ oil sands tailings geotechnical studies in order to determine pore pressure dissipation, and measure shear strength. Ball penetration tests are conducted to determine tailings strength. Methods of interpreting data from the tests were presented, and data from the tests were also compared and evaluated. Recommended procedures for strength screening were presented. Statistical methods for determining tailings behaviour types were outlined. The study showed that Gamma-CPTu data can be used to obtain reasonable preliminary estimates of solids and fines when combined with tailings behaviour type analyses. tabs., figs.

  1. The problem of abandoned uranium tailings in northern Saskatchewan

    International Nuclear Information System (INIS)

    Swanson, S.; Abouguendia, Z.

    1981-11-01

    Two Saskatchewan tailings sites, Lorado and Gunnar, covering approximately 89 ha., were abandoned in the early 1960s leaving untreated tailings in lakes and depressions. This report reviews the literature on environmental conditions in abandoned uranium tailings and available managmenet and mitigation options, and identifies research requirements essential for proper treatment of these two sites. The recommended management plan includes isolation of the exposed tailings area from surface waters, stabilization of the exposed tailings surfaces, diversion of runoff around tailings, treatment of overflow water before release, and implementation of an environmental monitoring program. Revegetation appears to be a promising stabilization measure, but research is needed into propagation methods of appropriate native species. Studies of the existing geological and hydrological conditions at both sites, detailed characterization of the wastes, field testing of different surface treatment methods, and nutrient cycling investigations are also needed

  2. Utilization of mine tailings as partial cement replacement

    DEFF Research Database (Denmark)

    Sigvardsen, Nina Marie; Nielsen, M.R.; Ottosen, Lisbeth M.

    2017-01-01

    Depositing mine tailings entail major economic costs and negative environmental impacts. Thus finding an alternative to depositing is of interest. This study focused on the use of mine tailings as partial cement replacement, thereby preventing depositing the mine tailings. At the same time......, such use would reduce the CO2 emission related to the production of cement. Mine tailings from two different mines Zinkgruvan (Sweden) and Nalunaq (Greenland) were both tested as 5 and 10 % cement replacement. All mortar specimens with mine tailings had lower compressive strength compared to a reference...... compared to a specimen containing a 10 % replacement of cement with coal fly ash, commonly used in Denmark. The compressive strength of specimens containing mine tailings exceeded the compressive strength of the specimen containing coal fly ash, indicating further the amorphous content of volcanic decent...

  3. Solar wind interaction with type-1 comet tails

    International Nuclear Information System (INIS)

    Ershkovich, A.I.

    1977-01-01

    A comet tail is considered as a plasma cylinder separated by a tangential discontinuity surface from the solar wind. Under typical conditions a comet tail boundary is shown to undergo the Kelvin-Helmholtz instability. With infinite amplitude the stabilizing effect of the magnetic field increases, and waves become stable. The proposed model supplies the detailed quantitative description of helical waves observed in type-1 comet tails. This theory enables the evaluation of the comet tail magnetic field by means of the observations of helical waves. The magnetic field in the comet tail turns out to be of the order of the interplanetary field. This conclusion seems to be in accordance with Alfven's idea that the magnetic field in type-1 comet tails is a captured interplanetary field. (Auth.)

  4. Flotation tailings as a raw material for ceramic building materials

    Energy Technology Data Exchange (ETDEWEB)

    Burmistrov, V N; Karpunina, T I; Smolin, V N

    1986-02-01

    The VNIIstrom research institute developed a method for utilizing flotation tailings for production of bricks. Tailings are dewatered using filter presses. After dewatering, moisture content in the tailings ranges from 25 to 26%. Tailings are mixed with chamotte with a grain size to 2 mm. Using 30% chamotte improves mechanical and physical properties of the bricks and reduces energy consumption of brick firing. Tailings mixed with chamotte are granulated and dried on a conveyor. Granules with moisture content reduced to the optimum level are mixed a second time and formed in a press. The bricks are fired in a tunnel kiln with modified design. The bricks made of flotation tailings mixed with 30% chamotte are characterized by mechanical properties comparable to those of high quality bricks made of conventional materials.

  5. Naphtha evaporation from oil sands tailings ponds

    Energy Technology Data Exchange (ETDEWEB)

    Kasperski, K.; Munoz, V.; Mikula, R. [Natural Resources Canada, Devon, AB (Canada). CANMET Western Research Centre

    2010-07-01

    The environmental impacts of volatile organic compounds (VOCs) from oil sands tailings ponds must be considered when evaluating new oil sands mining and extraction operations. Studies have suggested that only 40 percent of the solvent sent to tailings ponds is available to the environment, while the rest is irreversibly trapped. The recovery of hydrocarbons from oil sands froth process water is low. This PowerPoint presentation discussed a method of distinguishing between water and hydrocarbons at low temperatures. Samples were heated to 246 degrees C at 15 degrees C and held for 10 minutes. Heating was then resumed at 750 degrees C and held for 10 minutes in a pyrolysis phase, then cooled and reheated with an oxygen addition. The method demonstrated that the diluent distribution between the solids and water phases is misinterpreted as diluent that will evaporate, and diluent that will not evaporate. The study concluded by suggesting that the definition of recoverable and unrecoverable hydrocarbon should be re-termed as easily recoverable, and difficult to recover. tabs., figs.

  6. Efficient bootstrap estimates for tail statistics

    Science.gov (United States)

    Breivik, Øyvind; Aarnes, Ole Johan

    2017-03-01

    Bootstrap resamples can be used to investigate the tail of empirical distributions as well as return value estimates from the extremal behaviour of the sample. Specifically, the confidence intervals on return value estimates or bounds on in-sample tail statistics can be obtained using bootstrap techniques. However, non-parametric bootstrapping from the entire sample is expensive. It is shown here that it suffices to bootstrap from a small subset consisting of the highest entries in the sequence to make estimates that are essentially identical to bootstraps from the entire sample. Similarly, bootstrap estimates of confidence intervals of threshold return estimates are found to be well approximated by using a subset consisting of the highest entries. This has practical consequences in fields such as meteorology, oceanography and hydrology where return values are calculated from very large gridded model integrations spanning decades at high temporal resolution or from large ensembles of independent and identically distributed model fields. In such cases the computational savings are substantial.

  7. Environmental impact analysis of mine tailing reservoir

    Science.gov (United States)

    Gong, J. Z.

    2016-08-01

    Under certain conditions landscape topography which utilizes mine tailing reservoir construction using is likely to increase lateral recharge source regions, resulting in dramatic changes to the local hydrological dynamic field and recharge of downstream areas initiated by runoff, excretion state, elevated groundwater depth, shallow groundwater, rainfall direct communication, and thinning of the vadose zone. Corrosive leaching of topsoil over many years of exposure to chemical fertilizers and pesticides may result in their dissolution into the groundwater system, which may lead to excessive amounts of many harmful chemicals, therby affecting the physical and mental health of human residents and increase environmental vulnerability and risk associated with the water and soil. According to field survey data from Yujiakan, Qian'an City, and Hebei provinces, this paper analyzes the hydrogeological environmental mechanisms of areas adjacent to mine tailing reservoirs and establishes a conceptual model of the local groundwater system and the concentration-response function between NO3 - content in groundwater and the incidence of cancer in local residents.

  8. Submarine Tailings Disposal (STD—A Review

    Directory of Open Access Journals (Sweden)

    Bernhard Dold

    2014-07-01

    Full Text Available The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the waste/metal production ratio. Mine wastes deposited on-land in so-called tailings dams, impoundments or waste-dumps have several associated environmental issues that need to be addressed (e.g., acid mine drainage formation due to sulphide oxidation, geotechnical stability, among others, and social concerns due to land use during mining. The mining industry recognizes these concerns and is searching for waste management alternatives for the future. One option used in the past was the marine shore or shallow submarine deposition of this waste material in some parts of the world. After the occurrence of some severe environmental pollution, today the deposition in the deep sea (under constant reducing conditions is seen as a new, more secure option, due to the general thought that sulphide minerals are geochemically stable under the reduced conditions prevailing in the deep marine environment. This review highlights the mineralogical and geochemical issues (e.g., solubility of sulphides in seawater; reductive dissolution of oxide minerals under reducing conditions, which have to be considered when evaluating whether submarine tailings disposal is a suitable alternative for mine waste.

  9. Oil sands tailings leachability and toxicity evaluation

    International Nuclear Information System (INIS)

    Gulley, J.R.

    1995-01-01

    Fine tailings disposal and reclamation is a major issue facing the oil sands mining and extraction industry. Government regulations dictate that reclamation must return the site to a level of self-sustaining biological capability which approximates the natural condition. A two-phase laboratory program has been completed to investigate the suitability of alternative reclamation materials. For the first phase of the study, chemical and toxicological analyses were carried out on 13 different reclamation and reference materials (solid phase and extractions). Seedling emergence, nematode maturation, algal growth and bacterial luminescence for leachate samples showed a range of sensitivities in response to the tested materials, although phytotoxicity tests were generally the most sensitive. With the exception of one test material, high toxicity ratings were consistent with that expected from the chemical data. The second phase of the study focused on the evaluation of chemical and toxicological conditions in leachate water generated using bench-scale column percolation tests. Leachate water equivalent to 10 pore volume replacements was generated and temporal variations in toxicity and chemistry monitored. Similar to phase 1 findings, phytotoxicity tests were the most sensitive tests to leachate waters. For most materials tested, most toxicity was removed after 2--3 porewater replacements. More persistent toxicity was noted for samples containing bitumen (e.g., fine tails and oil sands). No clear correspondence was noted between chemical concentrations and toxicity in leachate waters

  10. Sulfur biogeochemistry of oil sands composite tailings

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Lesley; Stephenson, Kate [Earth Sciences, McMaster University (Canada)], email: warrenl@mcmaster.ca; Penner, Tara [Syncrude Environmental Research (Canada)

    2011-07-01

    This paper discusses the sulfur biogeochemistry of oil sands composite tailings (CT). The Government of Alberta is accelerating reclamation activities on composite tailings. As a CT pilot reclamation operation, Syncrude is currently constructing the first freshwater fen. Minor unpredicted incidents with H2S gas released from the dewatering process associated with these reclamations have been reported. The objective of this study is to ascertain the connection between microbial activity and H2S generation within CT and to assess the sulfur biogeochemistry of untreated and treated (fen) CT over seasonal and annual timescales. The microbial geochemical interactions taking place are shown using a flow chart. CT is composed of gypsum, sand, clay and organics like naphthenic acids and bitumen. Sulfur and Fe cycling in mining systems and their microbial activities are presented. The chemistry and the processes involved within CT are also given along with the results. It can be said that the diverse Fe and S metabolizing microorganisms confirm the ecology involved in H2S dynamics.

  11. Uranium mill tailings backfill management. Final report

    International Nuclear Information System (INIS)

    Thomson, B.M.; Heggen, R.J.

    1984-01-01

    Backfilling, the disposal of spent uranium mill tailings in empty mine stopes, has been practiced in the Grants Mineral Belt of New Mexico for nearly 20 years. The principal objective of backfilling is the prevention of roof collapse and hydraulic connection with overlying aquifers, increasing mine dewatering requirements. Backfilling is accomplished by gravity feed of a slurry of sand-fraction tailings and treated mine water into the slope. The effects of backfilling on surface discharge of mine wastewater are negligible due to the small fraction of the total flow represented by slurry decant. Furthermore, quality of the decant is not significantly below that of other mine waters. Groundwater effects of backfilling may be classified as short-term (while the mine is operational) and long-term (after dewatering operations have been terminated). Short-term effects are insignificant because of rapid and continuous flow to the mine sump. Long-term effects on aquifer water quality are predicted to be minimal due to (1) the small amount of slurry liquor present after drainage, (2) the precipitation of SO 4 and CO 3 phases, and (3) the reestablishment of reducing conditions and subsequent precipitation of major contaminants including U, As, Mo, Se, and V. 28 references, 19 figures, 9 tables

  12. The big head and the long tail

    DEFF Research Database (Denmark)

    Helles, Rasmus

    2013-01-01

    This paper discusses how the advent of big data challenges established theories in Internet studies to redevelop existing explanatory strategies in order to incorporate the possibilities offered by this new empirical resource. The article suggests that established analytical procedures and theore......This paper discusses how the advent of big data challenges established theories in Internet studies to redevelop existing explanatory strategies in order to incorporate the possibilities offered by this new empirical resource. The article suggests that established analytical procedures...... and theoretical frameworks used in Internet studies can be fruitfully employed to explain high–level structural phenomena that are only observable through the use of big data. The present article exemplifies this by offering a detailed analysis of how genre analysis of Web sites may be used to shed light...... on the generative mechanism behind the long–tail distribution of Web site use. The analysis shows that the long tail should be seen as a tiered version of popular top sites, and argues that downsizing of large–scale datasets in combination with qualitative and/or small–scale quantitative procedures may provide...

  13. Transverse tails and higher order moments

    International Nuclear Information System (INIS)

    Spence, W.L.; Decker, F.J.; Woodley, M.D.

    1993-05-01

    The tails that may be engendered in a beam's transverse phase space distribution by, e.g., intrabunch wakefields and nonlinear magnetic fields, are all important diagnostic and object of tuning in linear colliders. Wire scanners or phosphorescent screen monitors yield one dimensional projected spatial profiles of such beams that are generically asymmetric around their centroids, and therefore require characterization by the third moment left-angle x 3 right-angle in addition to the conventional mean-square or second moment. A set of measurements spread over sufficient phase advance then allows the complete set left-angle x 3 right-angle, left-angle xx' 2 right-angle, left-angle x' 3 right-angle, and left-angle x 2 x'right-angle to be deduced -- the natural extension of the well-known ''emittance measurement'' treatment of second moments. The four third moments may be usefully decomposed into parts rotating in phase space at the β-tron frequency and at its third harmonic, each specified by a phase-advance-invariant amplitude and a phase. They provide a framework for the analysis and tuning of transverse wakefield tails

  14. Electron distribution function in laser heated plasmas

    International Nuclear Information System (INIS)

    Fourkal, E.; Bychenkov, V. Yu.; Rozmus, W.; Sydora, R.; Kirkby, C.; Capjack, C. E.; Glenzer, S. H.; Baldis, H. A.

    2001-01-01

    A new electron distribution function has been found in laser heated homogeneous plasmas by an analytical solution to the kinetic equation and by particle simulations. The basic kinetic model describes inverse bremsstrahlung absorption and electron--electron collisions. The non-Maxwellian distribution function is comprised of a super-Gaussian bulk of slow electrons and a Maxwellian tail of energetic particles. The tails are heated due to electron--electron collisions and energy redistribution between superthermal particles and light absorbing slow electrons from the bulk of the distribution function. A practical fit is proposed to the new electron distribution function. Changes to the linear Landau damping of electron plasma waves are discussed. The first evidence for the existence of non-Maxwellian distribution functions has been found in the interpretation, which includes the new distribution function, of the Thomson scattering spectra in gold plasmas [Glenzer , Phys. Rev. Lett. 82, 97 (1999)

  15. Manual for the sampling of uranium mine tailings

    International Nuclear Information System (INIS)

    Feenstra, S.; Reades, D.W.; Cherry, J.A.; Chambers, D.B.; Case, G.G.; Ibbotson, B.G.

    1983-04-01

    The purpose of this manual is to describe the requisite sampling procedures to provide a basis for the application of uniform high-quality standards to detailed geotechnical, hydrogeological, geochemical and air quality measurements at Canadian uranium tailings disposal sites. The report describes the objective and scope of a sampling program, the preliminary data collection, and the procedures for sampling of tailings solids, surface water and seepage, tailings porewater, and wind-blown dust and radon

  16. Reclamation of copper mine tailings using sewage sludge

    OpenAIRE

    Stjernman Forsberg, Lovisa

    2008-01-01

    Tailings are the fine-grained fraction of waste produced during mining operations. This work was carried out on tailings from the Aitik copper mine in northern Sweden. Establishment of vegetation on the Aitik mine tailings deposit is planned to take place at closure of the mine, using sewage sludge as fertiliser. However, the tailings contain traces of metal sulphides, e.g. pyrite, FeS2, and chalcopyrite, CuFeS2. When the sulphides are oxidised, they start to weather and release metals and st...

  17. Ecological restoration alters microbial communities in mine tailings profiles.

    Science.gov (United States)

    Li, Yang; Jia, Zhongjun; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

    2016-04-29

    Ecological restoration of mine tailings have impact on soil physiochemical properties and microbial communities. The surface soil has been a primary concern in the past decades, however it remains poorly understood about the adaptive response of microbial communities along the profile during ecological restoration of the tailings. In this study, microbial communities along a 60-cm profile were investigated in a mine tailing pond during ecological restoration of the bare waste tailings (BW) with two vegetated soils of Imperata cylindrica (IC) and Chrysopogon zizanioides (CZ) plants. Revegetation of both IC and CZ could retard soil degradation of mine tailing by stimulation of soil pH at 0-30 cm soils and altered the bacterial communities at 0-20 cm depths of the mine tailings. Significant differences existed in the relative abundance of the phyla Alphaproteobacteria, Deltaproteobacteria, Acidobacteria, Firmicutes and Nitrospira. Slight difference of bacterial communities were found at 30-60 cm depths of mine tailings. Abundance and activity analysis of nifH genes also explained the elevated soil nitrogen contents at the surface 0-20 cm of the vegetated soils. These results suggest that microbial succession occurred primarily at surface tailings and vegetation of pioneering plants might have promoted ecological restoration of mine tailings.

  18. (measured as NDVI) over mine tailings at Mhangura Copper Mine

    African Journals Online (AJOL)

    chari

    Remote sensing techniques are increasingly being employed in monitoring environmental ... normalised difference vegetation index (NDVI), remote sensing, tailings ..... rehabilitation monitoring by adding landscape function characteristics.

  19. Review of fugitive dust control for uranium mill tailings

    International Nuclear Information System (INIS)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques

  20. A tale of two tails: Not just skin deep

    Directory of Open Access Journals (Sweden)

    Abhijit Dutta

    2015-01-01

    Full Text Available The dorsal cutaneous appendage or the so called human tail is a rare congenital anomaly protruding from the lumbo-sacro-coccygeal area. These caudal appendages are divided into true-tails and pseudo-tails. We report here two cases of congenital pseudo-tail with underlying spina bifida and lipo-meningocele. In this article we seek to emphasize that, as the skin and nervous systems are intimately linked by their similar ectodermal origin, a dorsal appendage may be regarded as a cutaneous marker of the underlying spinal dysraphism.

  1. Top Incomes, Heavy Tails, and Rank-Size Regressions

    Directory of Open Access Journals (Sweden)

    Christian Schluter

    2018-03-01

    Full Text Available In economics, rank-size regressions provide popular estimators of tail exponents of heavy-tailed distributions. We discuss the properties of this approach when the tail of the distribution is regularly varying rather than strictly Pareto. The estimator then over-estimates the true value in the leading parametric income models (so the upper income tail is less heavy than estimated, which leads to test size distortions and undermines inference. For practical work, we propose a sensitivity analysis based on regression diagnostics in order to assess the likely impact of the distortion. The methods are illustrated using data on top incomes in the UK.

  2. Ecological restoration alters microbial communities in mine tailings profiles

    Science.gov (United States)

    Li, Yang; Jia, Zhongjun; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

    2016-04-01

    Ecological restoration of mine tailings have impact on soil physiochemical properties and microbial communities. The surface soil has been a primary concern in the past decades, however it remains poorly understood about the adaptive response of microbial communities along the profile during ecological restoration of the tailings. In this study, microbial communities along a 60-cm profile were investigated in a mine tailing pond during ecological restoration of the bare waste tailings (BW) with two vegetated soils of Imperata cylindrica (IC) and Chrysopogon zizanioides (CZ) plants. Revegetation of both IC and CZ could retard soil degradation of mine tailing by stimulation of soil pH at 0-30 cm soils and altered the bacterial communities at 0-20 cm depths of the mine tailings. Significant differences existed in the relative abundance of the phyla Alphaproteobacteria, Deltaproteobacteria, Acidobacteria, Firmicutes and Nitrospira. Slight difference of bacterial communities were found at 30-60 cm depths of mine tailings. Abundance and activity analysis of nifH genes also explained the elevated soil nitrogen contents at the surface 0-20 cm of the vegetated soils. These results suggest that microbial succession occurred primarily at surface tailings and vegetation of pioneering plants might have promoted ecological restoration of mine tailings.

  3. Review of fugitive dust control for uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques.

  4. Modelling of contaminant release from a uranium mine tailings site

    International Nuclear Information System (INIS)

    Kahnt, Rene; Metschies, Thomas

    2007-01-01

    Available in abstract form only. Full text of publication follows: Uranium mining and milling continuing from the early 1960's until 1990 close to the town of Seelingstaedt in Eastern Germany resulted in 4 tailings impoundments with a total tailings volume of about 105 Mio. m 3 . Leakage from these tailings impoundments enters the underlying aquifers and is discharged into surface water streams. High concentration of salts, uranium and several heavy metals are released from the tailings. At present the tailings impoundments are reshaped and covered. For the identification of suitable remediation options predictions of the contaminant release for different remediation scenarios have to be made. A compartment model representing the tailings impoundments and the surrounding aquifers for the calculation of contaminant release and transport was set up using the software GOLDSIM. This compartment model describes the time dependent hydraulic conditions within the tailings and the surrounding aquifers taking into account hydraulic and geotechnical processes influencing the hydraulic properties of the tailings material. A simple geochemical approach taking into account sorption processes as well as retardation by applying a k d -approach was implemented to describe the contaminant release and transport within the hydraulic system. For uranium as the relevant contaminant the simple approach takes into account additional geochemical conditions influencing the mobility. Alternatively the model approach allows to include the results of detailed geochemical modelling of the individual tailings zones which is than used as source term for the modelling of the contaminant transport in the aquifer and to the receiving streams. (authors)

  5. Estimating impact forces of tail club strikes by ankylosaurid dinosaurs.

    Directory of Open Access Journals (Sweden)

    Victoria Megan Arbour

    Full Text Available BACKGROUND: It has been assumed that the unusual tail club of ankylosaurid dinosaurs was used actively as a weapon, but the biological feasibility of this behaviour has not been examined in detail. Ankylosaurid tail clubs are composed of interlocking vertebrae, which form the handle, and large terminal osteoderms, which form the knob. METHODOLOGY/PRINCIPAL FINDINGS: Computed tomographic (CT scans of several ankylosaurid tail clubs referred to Dyoplosaurus and Euoplocephalus, combined with measurements of free caudal vertebrae, provide information used to estimate the impact force of tail clubs of various sizes. Ankylosaurid tails are modeled as a series of segments for which mass, muscle cross-sectional area, torque, and angular acceleration are calculated. Free caudal vertebrae segments had limited vertical flexibility, but the tail could have swung through approximately 100 degrees laterally. Muscle scars on the pelvis record the presence of a large M. longissimus caudae, and ossified tendons alongside the handle represent M. spinalis. CT scans showed that knob osteoderms were predominantly cancellous, which would have lowered the rotational inertia of the tail club and made it easier to wield as a weapon. CONCLUSIONS/SIGNIFICANCE: Large knobs could generate sufficient force to break bone during impacts, but average and small knobs could not. Tail swinging behaviour is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both.

  6. Proceedings of the 15. annual British Columbia MEND ML/ARD workshop : the management of tailings and tailings impoundments

    International Nuclear Information System (INIS)

    2009-02-01

    This Mine Environment Neutral Drainage (MEND) workshop was held to promote the exchange of information and ideas on environmental protection and reclamation associated with mining. The workshop covered a broad spectrum of reclamation issues and the key environmental challenges facing the mining industry, such as acid mine drainage (AMD) control, and metal leaching and acid rock drainage (ML/ARD). The theme for the 2008 workshop was the management of tailings and tailings impoundments. Topics of discussion included hydrogeology and geochemistry; tailings disposal; mitigation; closure plans; and postclosure performance. The emphasis was on full-scale case studies, practical constraints and sustaining successful disposal strategies and remediation. The session on tailings management reviewed overarching policies and practices; methods of subaerial tailings disposal and case studies of tailings management; and detailed investigations of geochemical properties and processes. The conference featured 22 presentations, of which 4 have been catalogued separately for inclusion in this database. refs., tabs., figs

  7. Chaperone role for proteins p618 and p892 in the extracellular tail development of Acidianus two-tailed virus

    DEFF Research Database (Denmark)

    Scheele, Urte; Erdmann, Susanne; Ungewickell, Ernst J.

    2011-01-01

    The crenarchaeal Acidianus two-tailed virus (ATV) undergoes a remarkable morphological development, extracellularly and independently of host cells, by growing long tails at each end of a spindle-shaped virus particle. Initial work suggested that an intermediate filament-like protein, p800...... the interactions observed between the different protein and DNA components and to explain their possible structural and functional roles in extracellular tail development....

  8. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata.

    Directory of Open Access Journals (Sweden)

    Ori Segev

    Full Text Available Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping--i.e., bites inflicted by predators including conspecifics--on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail on Near Eastern fire salamander (Salamandra infraimmaculata larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample.

  9. THE NARROW X-RAY TAIL AND DOUBLE Hα TAILS OF ESO 137-002 IN A3627

    International Nuclear Information System (INIS)

    Zhang, B.; Lin, X. B.; Kong, X.; Sun, M.; Ji, L.; Sarazin, C.; Nulsen, P. E. J.; Forman, W.; Jones, C.; Roediger, E.; Donahue, M.; Voit, G. M.

    2013-01-01

    We present the analysis of a deep Chandra observation of a ∼2 L * late-type galaxy, ESO 137-002, in the closest rich cluster A3627. The Chandra data reveal a long (∼>40 kpc) and narrow tail with a nearly constant width (∼3 kpc) to the southeast of the galaxy, and a leading edge ∼1.5 kpc from the galaxy center on the upstream side of the tail. The tail is most likely caused by the nearly edge-on stripping of ESO 137-002's interstellar medium (ISM) by ram pressure, compared to the nearly face-on stripping of ESO 137-001 discussed in our previous work. Spectral analysis of individual regions along the tail shows that the gas throughout it has a rather constant temperature, ∼1 keV, very close to the temperature of the tails of ESO 137-001, if the same atomic database is used. The derived gas abundance is low (∼0.2 solar with the single-kT model), an indication of the multiphase nature of the gas in the tail. The mass of the X-ray tail is only a small fraction (<5%) of the initial ISM mass of the galaxy, suggesting that the stripping is most likely at an early stage. However, with any of the single-kT, double-kT, and multi-kT models we tried, the tail is always 'over-pressured' relative to the surrounding intracluster medium (ICM), which could be due to the uncertainties in the abundance, thermal versus non-thermal X-ray emission, or magnetic support in the ICM. The Hα data from the Southern Observatory for Astrophysical Research show a ∼21 kpc tail spatially coincident with the X-ray tail, as well as a secondary tail (∼12 kpc long) to the east of the main tail diverging at an angle of ∼23° and starting at a distance of ∼7.5 kpc from the nucleus. At the position of the secondary Hα tail, the X-ray emission is also enhanced at the ∼2σ level. We compare the tails of ESO 137-001 and ESO 137-002, and also compare the tails to simulations. Both the similarities and differences of the tails pose challenges to the simulations. Several implications are

  10. Tailings management best practice: a case study of the McClean Lake JEB Tailings Management Facility

    International Nuclear Information System (INIS)

    Tremblay, M.A.J.; Rowson, J.

    2005-01-01

    COGEMA Resources Inc. (which is part of the Areva Group) is a Canadian company with its head office in Saskatoon, Saskatchewan. It owns and operates mining and milling facilities in Northern Saskatchewan, which produce uranium concentrate. McClean Lake Operation commenced production in 1999 and its tailings management facility represents the state of the art for tailings management in the uranium industry in Canada. Tailings disposal has the potential to cause effects in the surrounding receiving environment primarily through migration of soluble constituents from the facility to surface water receptors. In-pit disposal or mill tailings has become the standard in the uranium mining industry in Northern Saskatchewan. This method or tailings management demonstrates advances in terms of worker radiation protection and containment of soluble constituents both during operations and into the long term. Sub-aqueous deposition of tailings protects personnel from exposure to radiation and airborne emissions and prevents freezing of tailings, which can hinder consolidation. The continuous inflow of groundwater to the facility is achieved during operations, through control of water levels within the facility. This ensures hydrodynamic containment, which prevents migration of soluble radionuclides and heavy metals into the surrounding aquifer during operations. The environmental performance of the decommissioned facility depends upon the rate of release of contaminants to the receiving environment. The rate of constituent loading to the receiving environment will ultimately be governed by the concentrations of soluble constituents within the tailings mass, the mechanisms for release from the tailings to the surrounding groundwater system, and transport of constituents within the groundwater pathway to the receiving environment. The tailings preparation process was designed to convert arsenic into a stable form to reduce soluble concentrations within the tailings mass. The

  11. A proactive approach to sustainable management of mine tailings

    Science.gov (United States)

    Edraki, Mansour; Baumgartl, Thomas

    2015-04-01

    The reactive strategies to manage mine tailings i.e. containment of slurries of tailings in tailings storage facilities (TSF's) and remediation of tailings solids or tailings seepage water after the decommissioning of those facilities, can be technically inefficient to eliminate environmental risks (e.g. prevent dispersion of contaminants and catastrophic dam wall failures), pose a long term economic burden for companies, governments and society after mine closure, and often fail to meet community expectations. Most preventive environmental management practices promote proactive integrated approaches to waste management whereby the source of environmental issues are identified to help make a more informed decisions. They often use life cycle assessment to find the "hot spots" of environmental burdens. This kind of approach is often based on generic data and has rarely been used for tailings. Besides, life cycle assessments are less useful for designing operations or simulating changes in the process and consequent environmental outcomes. It is evident that an integrated approach for tailings research linked to better processing options is needed. A literature review revealed that there are only few examples of integrated approaches. The aim of this project is to develop new tailings management models by streamlining orebody characterization, process optimization and rehabilitation. The approach is based on continuous fingerprinting of geochemical processes from orebody to tailings storage facility, and benchmark the success of such proactive initiatives by evidence of no impacts and no future projected impacts on receiving environments. We present an approach for developing such a framework and preliminary results from a case study where combined grinding and flotation models developed using geometallurgical data from the orebody were constructed to predict the properties of tailings produced under various processing scenarios. The modelling scenarios based on the

  12. Anisotropic distribution function of minority tail ions generated by strong ion-cyclotron resonance heating

    International Nuclear Information System (INIS)

    Chang, C.S.; Colestock, P.

    1989-05-01

    The highly anisotropic particle distribution function of minority tail ions driven by ion-cyclotron resonance heating at the fundamental harmonic is calculated in a two-dimensional velocity space. It is assumed that the heating is strong enough to drive most of the resonant ions above the in-electron critical slowing-down energy. Simple analytic expressions for the tail distribution are obtained fro the case when the Doppler effect is sufficiently large to flatten the sharp pitch angle dependence in the bounce averaged qualilinear heating coefficient, D/sub b/, and for the case when D/sub b/ is assumed to be constant in pitch angle and energy. It is found that a simple constant-D/sub b/ solution can be used instead of the more complicated sharp-D/sub b/ solution for many analytic purposes. 4 refs., 4 figs

  13. Neutral beams in two-ribbon flares and in the geomagnetic tail

    International Nuclear Information System (INIS)

    Martens, P.C.H.; Young, A.

    1990-01-01

    The current sheet created in the wake of an erupting filament during a two-ribbon flare is studied. A comparison with the geomagnetic tail shows that the physics of these systems is very similar, and therefore the existence of super Dreicer fields and the generation of netural beams traveling down the postflare loops with small pitch angles may be expected. The observational evidence for neutral beams in flares is reviewed and found to be generally supportive, while contracting the widely held hypothesis of electron beams. A dimensional analysis further demonstrates that the results for self-consistent numerical simulations of the current sheet in the geomagnetic tail can directly be scaled to the coronal current sheet, and the scaling parameters are derived. 71 refs

  14. Tailings dewatering in the oil sands

    Energy Technology Data Exchange (ETDEWEB)

    Longo, S.; Labelle, M. [Golder Paste Technology, Sudbury, ON (Canada); Wislesky, I. [Golder Associates Ltd., Calgary, AB (Canada)

    2010-07-01

    Alberta's Directive 074 was established to reduce fluid tailings produced during oil sands extraction processes. This PowerPoint presentation examined some of the dewatering strategies available for oil sands operators and provided recommendations for implementing a dewatering plan. Sites must be evaluated in order to determine their chemistry, mineralogy, and the total quantity of material to be handled. The availability of potential additives must also be considered. Process technologies must be selected in relation to the operator's depositional strategy. Each site will require its own unique dewatering and depositional strategy. Dewatering technologies include thickening; in-line flocculation; centrifuge; co-mingling; and various new technologies such as electro-osmosis. Laboratory testing programs include index tests, primary stream thickening, and mini-pilot plant testing. The performance of various testing formats was evaluated. Thickening and depositional techniques were reviewed. tabs., figs.

  15. Hollywood blockbusters and long-tailed distributions

    Science.gov (United States)

    Sinha, S.; Raghavendra, S.

    2004-11-01

    Numerical data for all movies released in theaters in the USA during the period 1997-2003 are examined for the distribution of their popularity in terms of (i) the number of weeks they spent in the Top 60 according to the weekend earnings, and (ii) the box-office gross during the opening week, as well as, the total duration for which they were shown in theaters. These distributions show long tails where the most popular movies are located. Like the study of Redner [S. Redner, Eur. Phys. J. B 4, 131 (1998)] on the distribution of citations to individual papers, our results appear to be consistent with a power-law dependence of the rank distribution of gross revenues for the most popular movies with a exponent close to -1/2.

  16. Erosion protection of uranium tailings impoundments

    International Nuclear Information System (INIS)

    Walters, W.H.; Skaggs, R.L.; Foley, M.G.; Beedlow, P.A.

    1986-09-01

    Pacific Northwest Laboratory (PNL) prepared this report to assist in the design and review of erosion protection works for decommissioned uranium tailings impoundments. The major causes of erosion over the long-term decommissioning period are from rainfall-runoff (overland flow) and stream channel flooding. The method of protection recommended for the impoundment side slopes and site drainage channels is rock riprap. Combinations of vegetation and rock mulch are recommended for the top surface. The design methods were developed from currently available procedures supplemented by field, laboratory, and mathematical model studies performed by PNL. Guidelines for the placement of riprap, inspection, and maintenance are presented. Other subjects discussed are rock selection and testing, slope stability, and overland erosion modeling

  17. The cost of decommissioning uranium mill tailings

    International Nuclear Information System (INIS)

    Lush, D.L.; Lendrum, C.; Hostovsky, C.; Eedy, W.; Ashbrook, A.

    1986-04-01

    This report identifies several key operations that are commonly carried out during decommissioning of tailings areas in the Canadian environment. These operations are unit costed for a generic site to provide a base reference case. The unit costs have also been scaled to the quantities required for the decommissioning of four Canadian sites and these scaled quantities compared with site-specific engineering cost estimates and actual costs incurred in carrying out the decommissioning activities. Variances in costing are discussed. The report also recommends a generic monitoring regime upon which both short- and longer-term environmental monitoring costs are calculated. Although every site must be addressed as a site-specific case, and monitoring programs must be tailored to fit a specific site, it would appear that for the conventional decommissioning and monitoring practices that have been employed to date, costs can be reasonably estimated when site-specific conditions are taken into account

  18. Electrokinetic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrián; Ottosen, Lisbeth M.

    2007-01-01

    Important process parameters to optimize in electrokinetic soil remediation are those influencing remediation time and power consumption since these directly affect the cost of a remediation action. This work shows how the electrokinetic remediation (EKR) process could be improved by implementing...... bipolar electrodes in the porous material. The bipolar electrodes in EKR meant two improvements: (1) a shorter migration pathway for the contaminant, and (2) an increased electrical conductivity in the remediation system. All together the remediation proceeded faster with lower electrical resistance than...... in similar experiments but without the bipolar electrodes. The new electrokinetic remediation design was tested on copper mine tailings with different applied electric fields, remediation times and pre-treatment. The results showed that the copper removal was increased from 8% (applying 20V for 8 days...

  19. Uranium mill tailings regulation and the generic environmental impact statement

    International Nuclear Information System (INIS)

    Rogers, V.C.

    1980-01-01

    The following topics are discussed: the history of the Canadian uranium industry; the Canadian management of uranium mining wastes; Canadian federal and provincial effluent guidelines for radium-226; tailings and mine water management; backfill; liquid effluents from tailings storage; barium chloride treatment; mine water (Fay Mine); mine water (Dubyna Mine); and revegetation. 22 refs

  20. On the average configuration of the geomagnetic tail

    International Nuclear Information System (INIS)

    Fairfield, D.H.

    1978-03-01

    Over 3000 hours of IMP-6 magnetic field data obtained between 20 and 33 R sub E in the geomagnetic tail have been used in a statistical study of the tail configuration. A distribution of 2.5 minute averages of B sub Z as a function of position across the tail reveals that more flux crosses the equatorial plane near the dawn and dusk flanks than near midnight. The tail field projected in the solar magnetospheric equatorial plane deviates from the X axis due to flaring and solar wind aberration by an angle alpha = -0.9 y sub SM - 1.7, where y/sub SM/ is in earth radii and alpha is in degrees. After removing these effects the Y component of the tail field is found to depend on interplanetary sector structure. During an away sector the B/sub Y/ component of the tail field is on average 0.5 gamma greater than that during a toward sector, a result that is true in both tail lobes and is independent of location across the tail

  1. Shrinkage and swelling properties of flocculated mature fine tailings

    NARCIS (Netherlands)

    Yao, Y.; Van Tol, A.F.; Van Paassen, L.A.; Vardon, P.J.

    2014-01-01

    In the atmospheric fines drying technique, mature fine tailings (MFT) are treated with polymers and deposited in thin layers on a sloped surface for sub-aerial drying. During the whole drying period, the tailings deposits can experience rewetting during periods of rainy weather or as result of the

  2. Geophysical applications for oil sand mine tailings management

    Energy Technology Data Exchange (ETDEWEB)

    Parker, D.; Bauman, P. [WorleyParsons, Calgary, AB (Canada)

    2009-07-01

    Geophysical techniques are applied throughout a mine's life cycle to facilitate siting, constructing and monitoring of tailings dumps and ponds. This presentation described 3 case studies from the Athabasca region in northeast Alberta that demonstrated some of the concerns associated with oil sand mine tailings, and the information that geophysical surveys can provide. The objectives of these studies were to determine the lateral and depth extents of elevated conductivities of soil and groundwater that have high salt concentration from the tailings sand pore fluid. Due to high chloride concentrations within the tailings material, salt within the root zone may affect vegetation. A terrain conductivity survey was designed to map the lateral extents of salinity impact, while an electrical resistivity tomography (ERT) survey was used to delineate the tailings sand leachate at depth. The proper management of oil sand tailings facilities is vital to the life cycle of a mine. It was concluded that geophysical techniques can be instrumental in managing several engineering and environmental challenges, from Pleistocene channel mapping, to tailings pond settling characteristics, to reclaiming tailings sands. 1 ref., 7 figs.

  3. Understanding AL-PAM assisted oil sands tailings treatment

    Energy Technology Data Exchange (ETDEWEB)

    Guo, L.; Maham, Y.; Masliyah, J.; Xu, Z. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2010-07-01

    Technologies currently used to treat oil sands tailings include the composite tailings (CT) process and the thickened tailings (TT) or paste technology process. This PowerPoint presentation discussed a flocculation and filtration method used to produce stackable tailings deposits. Magnafloc 1011 and AL-PAM additions were used as part of the filtration technique to produce very dry filter cakes. The effect of AL-PAM molecular weight and aluminum content on tailings treatments was investigated as well as the effect of tailings characteristics on the performance of flocculant-assisted tailings filtration processes. The AL-PAM molecular structure was studied. An experimental study was conducted to determine the effect of various polymer additions on fresh tailings from an oil sands plant. The study showed that the optimum dosage for settling and filtration was lower for higher molecular weight AL-PAM. A higher aluminum content was beneficial for settling. Increases in the aluminum content did not improve filtration rates, but reduced optimal dosages. Step-by-step details of the supernatant filtration process were provided, as well as photographs of the laboratory study. tabs., figs.

  4. Overview by Pioneer observations of the distant geomagnetic tail

    Energy Technology Data Exchange (ETDEWEB)

    Villante, U [L' Aquila Univ. (Italy). Istituto de Astrofisica

    1977-03-01

    Pioneer 7 and Pioneer 8 spacecraft provided the only direct observations of the geomagnetic tail at geocentric distances as large as 1000 Rsub(e) and 500 Rsub(e) respectively. The presence of a low density plasma flow in the region of expected tail and the intermittent and short duration character of the tail encounters suggested in the past a distant tail structure remarkably different from its near-earth and cislunar shape. However the recent discovery of the plasma mantle allows interpretation of the Pioneer observations in terms of a distant tail that possibly is still preserving most of its near-earth characteristics. In particular, the region of tail encounters and the magnitude and direction of the observed magnetic field might be consistent with a cylindrical tail with a modestly increased cross-section. Neutral sheet observations also appear to be consistent with the most recent bidimensional tail models. Finally, as in the cislunar region, the double peaked proton energy spectra can be interpreted in terms of a partial intermingling of plasma sheet and plasma mantle populations.

  5. measurement of radionuclides in processed mine tailings in jos

    African Journals Online (AJOL)

    DR. AMINU

    The mine tailings are associated with radioactive minerals as impurities such as monazite, zircon among others. ... milling. A total of thirty-one (31) tailing samples were collected from a processing site in Jos at ... radioactive elements remain active for a very long period of time ..... Measurement of Radioactivity levels in soil.

  6. Probing the density tail of radioactive nuclei with antiprotons

    CERN Document Server

    Obertelli, Alexandre; Uesaka, Tomohiro; Corsi, Anna; Pollacco, Emmanuel; Flavigny, Freddy

    2017-01-01

    We propose an experiment to determine the proton and neutron content of the radial density tail in short-lived nuclei. The objectives are to (i) to evidence new proton and neutron halos, (ii) to understand the development of neutron skins in medium-mass nuclei, (iii) to provide a new observable that characterises the density tail of short-lived nuclei.

  7. Characterisation of gold tailings dams of the Witwatersrand Basin ...

    African Journals Online (AJOL)

    2006-10-04

    Oct 4, 2006 ... bentonite layer between the 9th and 10th meter level to minimise vertical air flow from the bottom of the tailings dams. ... m depth with bentonite. Due to the age of the dams, and the fact that they ...... from Cyanide-Rich Gold Mine. Tailings. Unpublished M.Sc. Thesis, The University of New Bruns- wick, USA.

  8. Black-tailed prairie dog status and future conservation planning

    Science.gov (United States)

    Daniel W. Mulhern; Craig J. Knowles

    1997-01-01

    The black-tailed prairie dog is one of five prairie dog species estimated to have once occupied up to 100 million ha or more in North America. The area occupied by black-tailed prairie dogs has declined to approximately 2% of its former range. Conversion of habitat to other land uses and widespread prairie dog eradication efforts combined with sylvatic plague,

  9. Development in helicopter tail boom strake applications in the US

    Science.gov (United States)

    Wilson, John C.; Kelley, Henry L.; Donahue, Cynthia C.; Yenni, Kenneth R.

    1988-01-01

    The use of a strake or spoiler on a helicopter tail boom to beneficially change helicopter tail boom air loads was suggested in the United States in 1975. The anticipated benefits were a change of tail boom loads to reduce required tail rotor thrust and power and improve directional control. High tail boom air loads experienced by the YAH-64 and described in 1978 led to a wind tunnel investigation of the usefullness of strakes in altering such loads on the AH-64, UH-60, and UH-1 helicopters. The wind tunnel tests of 2-D cross sections of the tail boom of each demonstrated that a strake or strakes would be effective. Several limited test programs with the U.S. Army's OH-58A, AH-64, and UH-60A were conducted which showed the effects of strakes were modest for those helicopters. The most recent flight test program, with a Bell 204B, disclosed that for the 204B the tail boom strake or strakes would provide more than a modest improvement in directional control and reduction in tail rotor power.

  10. Studies on Arsenic Release and its Mitigation from Tailings Dam ...

    African Journals Online (AJOL)

    Studies on Arsenic Release and its Mitigation from Tailings Dam Using Nanomagnetite Particles. ... Ghana Mining Journal ... Abstract. Knowledge of the geochemistry of As in tailings material after beneficiation of gold-bearing sulphidic ores is necessary to comprehend the nature, stability and mobilization of As into the ...

  11. Mineralogy of Tailings Dump around Selebi Phikwe Nickel-Copper ...

    African Journals Online (AJOL)

    This study aimed at mineralogically characterizing the tailings dump emanating from the mining and smelting of nickel-copper (Ni-Cu) at Selebi Phikwe, Botswana, Southern Africa. Samples of tailings dump around the Selebi Phikwe Ni-Cu plant were studied using petrographic microscopy and X-ray Powder Diffraction ...

  12. Tail index and quantile estimation with very high frequency data

    NARCIS (Netherlands)

    J. Daníelsson (Jón); C.G. de Vries (Casper)

    1997-01-01

    textabstractA precise estimation of the tail shape of forex returns is of critical importance for proper risk assessment. We improve upon the efficiency of conventional estimators that rely on a first order expansion of the tail shape, by using the second order expansion. Here we advocate a moments

  13. Computer simulations of long-time tails: what's new?

    NARCIS (Netherlands)

    Hoef, van der M.A.; Frenkel, D.

    1995-01-01

    Twenty five years ago Alder and Wainwright discovered, by simulation, the 'long-time tails' in the velocity autocorrelation function of a single particle in fluid [1]. Since then, few qualitatively new results on long-time tails have been obtained by computer simulations. However, within the

  14. Population characteristics of a central Appalachian white tailed deer herd

    Science.gov (United States)

    Tyler A. Campbell; Benjamin R. Laseter; W. Mark Ford; Karl V. Miller; Karl V. Miller

    2005-01-01

    Reliable estimates of white-tailed deer (Odocoileus virginianus) population parameters are needed for effective population management. We used radiotelemetrv to compare survival and cause-specific mortality rates between male and female white-tailed deer and present reproductive data for a high-density deer herd in the central Appalachians of West Virginia during...

  15. Estimating contaminant discharge rates from stabilized uranium tailings embankments

    International Nuclear Information System (INIS)

    Weber, M.F.

    1986-01-01

    Estimates of contaminant discharge rates from stabilized uranium tailings embankments are essential in evaluating long-term impacts of tailings disposal on groundwater resources. Contaminant discharge rates are a function of water flux through tailings covers, the mass and distribution of tailings, and the concentrations of contaminants in percolating pore fluids. Simple calculations, laboratory and field testing, and analytical and numerical modeling may be used to estimate water flux through variably-saturated tailings under steady-state conditions, which develop after consolidation and dewatering have essentially ceased. Contaminant concentrations in water discharging from the tailings depend on tailings composition, leachability and solubility of contaminants, geochemical conditions within the embankment, tailings-water interactions, and flux of water through the embankment. These concentrations may be estimated based on maximum reported concentrations, pore water concentrations, extrapolations of column leaching data, or geochemical equilibria and reaction pathway modeling. Attempts to estimate contaminant discharge rates should begin with simple, conservative calculations and progress to more-complicated approaches, as necessary

  16. Comparing downside risk measures for heavy tailed distributions

    NARCIS (Netherlands)

    Daníelsson, J.; Jorgensen, B.N.; Sarma, M.; Vries, de C.G.

    2006-01-01

    Using regular variation to define heavy tailed distributions, we show that prominent downside risk measures produce similar and consistent ranking of heavy tailed risk. Thus, regardless of the particular risk measure being used, assets will be ranked in a similar and consistent manner for heavy

  17. Lower Tail Dependence for Archimedean Copulas : Characterizations and Pitfalls

    NARCIS (Netherlands)

    Charpentier, A.; Segers, J.J.J.

    2006-01-01

    Tail dependence copulas provide a natural perspective from which one can study the dependence in the tail of a multivariate distribution.For Archimedean copulas with continuously differentiable generators, regular variation of the generator near the origin is known to be closely connected to

  18. An M-estimator of multivariate tail dependence

    NARCIS (Netherlands)

    Krajina, A.

    2010-01-01

    AN M-ESTIMATOR OF TAIL DEPENDENCE. Extreme value theory is the part of probability and statistics that provides the theoretical background for modeling events that almost never happen. The estimation of the dependence between two or more such unlikely events (tail dependence) is the topic of this

  19. Trace elements contamination of soils around gold mine tailings ...

    African Journals Online (AJOL)

    This study investigated the issue of tailings dams as a potential source of trace elements contamination in soils at the Obuasi gold mine in Ghana. Soil samples taken from depths of up to 12 cm and within a radius of 400 m from the tailings dams (active and recommissioned), were analysed for As, Cu, Pb and. Zn using ...

  20. Individual piglets' contribution to the development of tail biting

    NARCIS (Netherlands)

    Zonderland, J.J.; Kemp, B.; Bracke, M.B.M.; Hartog, den L.A.; Spoolder, H.A.M.

    2011-01-01

    Conflicting hypotheses exist about the contribution of individual pigs to the development of a tail-biting outbreak, but there is limited quantitative information to support or dismiss them. This study aims to quantify the development of tail-biting behaviour at pen and individual piglet level,

  1. Thresher sharks use tail-slaps as a hunting strategy.

    Science.gov (United States)

    Oliver, Simon P; Turner, John R; Gann, Klemens; Silvosa, Medel; D'Urban Jackson, Tim

    2013-01-01

    The hunting strategies of pelagic thresher sharks (Alopias pelagicus) were investigated at Pescador Island in the Philippines. It has long been suspected that thresher sharks hunt with their scythe-like tails but the kinematics associated with the behaviour in the wild are poorly understood. From 61 observations recorded by handheld underwater video camera between June and October 2010, 25 thresher shark shunting events were analysed. Thresher sharks employed tail-slaps to debilitate sardines at all times of day. Hunting events comprised preparation, strike, wind-down recovery and prey item collection phases, which occurred sequentially. Preparation phases were significantly longer than the others, presumably to enable a shark to windup a tail-slap. Tail-slaps were initiated by an adduction of the pectoral fins, a manoeuvre that changed a thresher shark's pitch promoting its posterior region to lift rapidly, and stall its approach. Tail-slaps occurred with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles. Thresher sharks were able to consume more than one sardine at a time, suggesting that tail-slapping is an effective foraging strategy for hunting schooling prey. Pelagic thresher sharks appear to pursue sardines opportunistically by day and night, which may make them vulnerable to fisheries. Alopiids possess specialist pectoral and caudal fins that are likely to have evolved, at least in part, for tail-slapping. The evidence is now clear; thresher sharks really do hunt with their tails.

  2. Moth tails divert bat attack: evolution of acoustic deflection.

    Science.gov (United States)

    Barber, Jesse R; Leavell, Brian C; Keener, Adam L; Breinholt, Jesse W; Chadwell, Brad A; McClure, Christopher J W; Hill, Geena M; Kawahara, Akito Y

    2015-03-03

    Adaptations to divert the attacks of visually guided predators have evolved repeatedly in animals. Using high-speed infrared videography, we show that luna moths (Actias luna) generate an acoustic diversion with spinning hindwing tails to deflect echolocating bat attacks away from their body and toward these nonessential appendages. We pit luna moths against big brown bats (Eptesicus fuscus) and demonstrate a survival advantage of ∼ 47% for moths with tails versus those that had their tails removed. The benefit of hindwing tails is equivalent to the advantage conferred to moths by bat-detecting ears. Moth tails lured bat attacks to these wing regions during 55% of interactions between bats and intact luna moths. We analyzed flight kinematics of moths with and without hindwing tails and suggest that tails have a minimal role in flight performance. Using a robust phylogeny, we find that long spatulate tails have independently evolved four times in saturniid moths, further supporting the selective advantage of this anti-bat strategy. Diversionary tactics are perhaps more common than appreciated in predator-prey interactions. Our finding suggests that focusing on the sensory ecologies of key predators will reveal such countermeasures in prey.

  3. Lifshitz Tails for the Interband Light Absorption Coefficient

    Indian Academy of Sciences (India)

    In this paper we consider the interband light absorption coefficient (ILAC) for various models. We show that at the lower and upper edges of the spectrum the Lifshitz tails behaviour of the density of states implies similar behaviour for the ILAC at appropriate energies. The Lifshitz tails property is also exhibited at some points ...

  4. A Glimpse of the genomic diversity of haloarchaeal tailed viruses

    Directory of Open Access Journals (Sweden)

    Ana eSencilo

    2014-03-01

    Full Text Available Tailed viruses are the most common isolates infecting prokaryotic hosts residing hypersaline environments. Archaeal tailed viruses represent only a small portion of all characterized tailed viruses of prokaryotes. But even this small dataset revealed that archaeal tailed viruses have many similarities to their counterparts infecting bacteria, the bacteriophages. Shared functional homologues and similar genome organizations suggested that all microbial tailed viruses have common virion architectural and assembly principles. Recent structural studies have provided evidence justifying this thereby grouping archaeal and bacterial tailed viruses into a single lineage. Currently there are 17 haloarchaeal tailed viruses with entirely sequenced genomes. Nine viruses have at least one close relative among the 17 viruses and, according to the similarities, can be divided into three groups. Two other viruses share some homologues and therefore are distantly related, whereas the rest of the viruses are rather divergent (or singletons. Comparative genomics analysis of these viruses offers a glimpse into the genetic diversity and structure of haloarchaeal tailed virus communities.

  5. The hydrogeochemistry of four inactive tailings impoundments: Perspectives on tailings pore-water evolution

    International Nuclear Information System (INIS)

    Blowes, D.W.; Cherry, J.A.; Reardon, E.J.

    1987-01-01

    Extensive hydrogeochemical investigations are currently underway at three inactive tailings impoundments in Canada. These programs include detailed measurements of pore-water and gas-phase geochemistry through the vadose zone and the groundwater zone. An extensive piezometer network has been installed at each location to monitor the groundwater flow regime. All of the impoundments studied have been inactive for 15 to 25 years, sufficient time for extensive tailings pore-water evolution. The study areas include a very high-sulfide impoundment, a low-sulfide, high-carbonate impoundment, a low-sulfide, very low-carbonate impoundment, and a moderately high-sulfide impoundment. The pore water at each of the sites has evolved in a distinctly different and characteristic manner, representing broad styles of tailings pore-water evolution. At the high sulfide impoundment the oxidation of sulfide minerals has resulted in low pH, high redox potential conditions, with Fe 2+ concentrations in excess of 60,000 mg/L. At a depth of about 40 cm a 10 cm thick layer of ferrous and calcium sulfate minerals has precipitated. This hardpan layer limits the downward movement of O 2 and infiltrating pore waters. As a result, the pore water chemistry, both above and below the hardpan layer, has remained relatively unchanged over the past 10 years. The low-sulfide, high-carbonate tailings are sufficiently well buffered that no low pH conditions are present. The high pH conditions limit the concentrations of the metals released by sulfide mineral oxidation to levels that are two or three orders of magnitude less than is observed at the high-sulfide site. Pore waters at the low-sulfide, low-carbonate site were sampled by other researchers from the University of Waterloo

  6. TIDAL TAILS OF MINOR MERGERS: STAR FORMATION EFFICIENCY IN THE WESTERN TAIL OF NGC 2782

    International Nuclear Information System (INIS)

    Knierman, Karen; Scowen, Paul; Jansen, Rolf A.; Knezek, Patricia M.; Wehner, Elizabeth

    2012-01-01

    While major mergers and their tidal debris are well studied, they are less common than minor mergers (mass ratios ∼ SFR ) to be several orders of magnitude less than expected from the total gas density. Together with extended FUV+NUV emission from Galaxy Evolution Explorer along the tail, this indicates a low global star formation efficiency in the tidal tail producing lower mass star clusters. The H II region that we observed has a local (few-kiloparsec scale) Σ SFR from Hα that is less than that expected from the total gas density, which is consistent with other observations of tidal debris. The star formation efficiency of this H II region inferred from the total gas density is low, but normal when inferred from the molecular gas density. These results suggest the presence of a very small, locally dense region in the western tail of NGC 2782 or of a low-metallicity and/or low-pressure star-forming region.

  7. Processes for extracting radium from uranium mill tailings

    International Nuclear Information System (INIS)

    Nirdosh, I.; Baird, M.H.; Muthuswami, S.V.

    1987-01-01

    This patent describes a process for the extraction of radium from uranium mill tailings solids including the steps of contacting the tailings with a liquid leaching agent, leaching the tailings therewith and subsequently separating the leachate liquid and the leached solids. The improvement described here is wherein the leaching agent comprises: (a) a complexing agent in an amount of from 2 to 10 times the stoichiometric amount needed to complex the metal ions to be removed thereby from the tailings; and (b) a reducing agent reducing the hydrolysable ions of the metal ions to be removed to their lower oxidation states, the reduction agent being present in an amount from 2 to 10 times the stoichiometric amount needed for reducing the hydrolysable metals present in the tailings

  8. Identification of poorly crystalline scorodite in uranium mill tailings

    International Nuclear Information System (INIS)

    Frey, R.; Rowson, J.; Hughes, K.; Rinas, C.; Warner, J.

    2010-01-01

    The McClean Lake mill, located in northern Saskatchewan, processes a variety of uranium ore bodies to produce yellowcake. A by-product of this process is an acidic waste solution enriched in arsenic, referred to as raffinate. The raffinate waste stream is treated in the tailings preparation circuit, where arsenic is precipitated as a poorly crystalline scorodite phase. Raffinate neutralization studies have successfully identified poorly crystalline scorodite using XRD, SEM, EM, XANES and EXAFS methods, but to date, scorodite has not been successfully identified within the whole tailing solids. During the summer of 2008, a drilling program sampled the in situ tailings within the McClean Lake tailings management facility. Samples from this drilling campaign were sent to the Canadian Light Source Inc. for EXAFS analysis. The sample spectra positively identify a poorly crystalline scorodite phase within the McClean tailings management facility. (author)

  9. Comprehensive Evaluation of Soil Near Uranium Tailings, Beishan City, China.

    Science.gov (United States)

    Xun, Yan; Zhang, Xinjia; Chaoliang, Chen; Luo, Xuegang; Zhang, Yu

    2018-06-01

    To evaluate the impact of uranium tailings on soil composition and soil microbial, six soil samples at different distance from the uranium tailings (Beishan City, China) were collected for further analysis. Concentrations of radionuclides ( 238 U and 232 Th), heavy metals (Mn, Cd, Cr, Ni, Zn, and Pb) and organochlorine pesticide were determined by ICP-MS and GC, they were significantly higher than those of the control. And the Average Well Color Development as well as the Shannon, the Evenness, and the Simpson index were calculated to evaluate the soil microbial diversity. The carbon utilization model of soil microbial community was also analyzed by Biolog-eco. All results indicated that uranium tailings leaded to excessive radionuclides and heavy metals, and decreased the diversity of the soil microbial community. Our study will provide a valuable basis for soil quality evaluation around uranium tailing repositories and lay a foundation for the management and recovery of uranium tailings.

  10. Recent hydrological observations from the Riverton and Maybell tailings piles

    International Nuclear Information System (INIS)

    Tokunaga, T.; Narasimhan, T.N.

    1982-01-01

    This paper reports on field and laboratory hydrologic studies of two inactive uranium mill tailings piles under the Uranium Mill Tailings Remedial Action Program (UMTRA). The ultimate goal of the studies is to evaluate the nature of the contaminant potential of the piles with sufficient detail so that appropriate remedial measures can be designed and implemented under the UMTRA Program. The field studies included the monitoring of hydraulic head profiles of the piles and infiltration tests. Both the field and laboratory results from the Riverton tailings indicate a great deal of spatial variability in hydraulic properties. It is determined that the bulk of the precipitation input at the Riverton tailings is lost by evapotranspiration within the upper meter of soil cover and tailings

  11. Micropore Structure of Cement-Stabilized Gold Mine Tailings

    Directory of Open Access Journals (Sweden)

    Joon Kyu Lee

    2018-03-01

    Full Text Available Mine tailings have often to be stabilized by mixing them with cementing agents. In this study, the pore structure of gold tailings stabilized with Portland cement was evaluated by means of mercury intrusion porosimetry. The investigation was conducted on samples prepared with different fractions of tailings and cement as well as on samples activated with elevated temperature curing and chemical (CaCl2 addition. It was observed that all mixed samples exhibit a mono-modal pore size distribution, indicating that the cement-stabilized tailings are characterized by a single-porosity structure. The results also showed that the higher fraction of tailings and cement leads to a dense and finer pore structure. The total porosity of mixture samples decreases with increasing curing temperature and CaCl2 concentration due to the acceleration of hydration reaction.

  12. The Rum Jungle tailings dam - chemical profile of the subsoil

    International Nuclear Information System (INIS)

    Lowson, R.T.; Evans, J.V.; Sarbutt, J.V.; Sinclair, G.; Folk, E.

    1987-09-01

    In a survey of soils below the Rum Jungle uranium mine tailings dam, parameters measured were pH, moisture content, particle distribution, total Cu, water-extractable Cu, Ca and SO 4 and acid-extractable Ra. The cation profile had a marked discontinuity at the soil/tailings interface. This was attributed to a complex hydrogeology and to the presence of a reduction zone in the soil immediately below the tailings. The tailings acted as an aquaclude to a water table which fluctuated with the monsoonal season. The reduction zone acted as a cation trap, preventing cation transport. The radium concentration dropped to levels acceptable to public health within a few centimetres of the soil/tailings interface

  13. Fat-tailed distributions data, diagnostics and dependence

    CERN Document Server

    Cooke, Roger M; Misiewicz, Jolanta

    2014-01-01

    This title is written for the numerate nonspecialist, and hopes to serve three purposes. First it gathers mathematical material from diverse but related fields of order statistics, records, extreme value theory, majorization, regular variation and subexponentiality. All of these are relevant for understanding fat tails, but they are not, to our knowledge, brought together in a single source for the target readership. Proofs that give insight are included, but for most fussy calculations the reader is referred to the excellent sources referenced in the text. Multivariate extremes are not treated. This allows us to present material spread over hundreds of pages in specialist texts in twenty pages. Chapter 5 develops new material on heavy tail diagnostics and gives more mathematical detail. Since variances and covariances may not exist for heavy tailed joint distributions, Chapter 6 reviews dependence concepts for certain classes of heavy tailed joint distributions, with a view to regressing heavy tailed variabl...

  14. Accelerated aging tests of liners for uranium mill tailings disposal

    International Nuclear Information System (INIS)

    Barnes, S.M.; Buelt, J.L.; Hale, V.Q.

    1981-11-01

    This document describes the results of accelerated aging tests to determine the long-term effectiveness of selected impoundment liner materials in a uranium mill tailings environment. The study was sponsored by the US Department of Energy under the Uranium Mill Tailings Remedial Action Project. The study was designed to evaluate the need for, and the performance of, several candidate liners for isolating mill tailings leachate in conformance with proposed Environmental Protection Agency and Nuclear Regulatory Commission requirements. The liners were subjected to conditions known to accelerate the degradation mechanisms of the various liners. Also, a test environment was maintained that modeled the expected conditions at a mill tailings impoundment, including ground subsidence and the weight loading of tailings on the liners. A comparison of installation costs was also performed for the candidate liners. The laboratory testing and cost information prompted the selection of a catalytic airblown asphalt membrane and a sodium bentonite-amended soil for fiscal year 1981 field testing

  15. The Onset of Magnetic Reconnection in Tail-Like Equilibria

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim; Kuznetsova, Masha

    1999-01-01

    Magnetic reconnection is a fundamental mode of dynamics in the magnetotail, and is recognized as the basic mechanisms converting stored magnetic energy into kinetic energy of plasma particles. The effects of the reconnection process are well documented by spacecraft observations of plasmoids in the distant magnetotail, or bursty bulk flows, and magnetic field dipolarizations in the near Earth region. Theoretical and numerical analyses have, in recent years, shed new light on the way reconnection operates, and, in particular, which microscopic mechanism supports the dissipative electric field in the associated diffusion region. Despite this progress, however. the question of how magnetic reconnection initiates in a tail-like magnetic field with finite flux threading the current i.sheet remains unanswered. Instead, theoretical studies supported by numerical simulations support the point-of-view that such plasma and current sheets are stable with respect to collisionless tearing mode. In this paper, we will further investigate this conclusion, with emphasis on the question whether it remains valid in plasma sheets with embedded thin current sheets. For this purpose, we perform particle-in-cell simulations of the driven formation of thin current sheets, and their subsequent evolution either to equilibrium or to instability of a tearing-type mode. In the latter case we will pay particular attention to the nature of the electric field contribution which unmagnetizes the electrons.

  16. Electron distribution functions in Io plasma torus

    International Nuclear Information System (INIS)

    Boev, A.G.

    2003-01-01

    Electron distribution functions measured by the Voyager 1 in different shares of the Io plasma torus are explained. It is proved that their suprathermal tails are formed by the electrical field induced by the 'Jupiter wind'. The Maxwellian parts of all these spectra characterize thermal equilibrium populations of electrons and the radiation of exited ions

  17. Radon emanation from backfilled mill tailings in underground uranium mine.

    Science.gov (United States)

    Sahu, Patitapaban; Mishra, Devi Prasad; Panigrahi, Durga Charan; Jha, Vivekananda; Patnaik, R Lokeswara; Sethy, Narendra Kumar

    2014-04-01

    Coarser mill tailings used as backfill to stabilize the stoped out areas in underground uranium mines is a potential source of radon contamination. This paper presents the quantitative assessment of radon emanation from the backfilled tailings in Jaduguda mine, India using a cylindrical accumulator. Some of the important parameters such as (226)Ra activity concentration, bulk density, bulk porosity, moisture content and radon emanation factor of the tailings affecting radon emanation were determined in the laboratory. The study revealed that the radon emanation rate of the tailings varied in the range of 0.12-7.03 Bq m(-2) s(-1) with geometric mean of 1.01 Bq m(-2) s(-1) and geometric standard deviation of 3.39. An increase in radon emanation rate was noticed up to a moisture saturation of 0.09 in the tailings, after which the emanation rate gradually started declining with saturation due to low diffusion coefficient of radon in the saturated tailings. Radon emanation factor of the tailings varied in the range of 0.08-0.23 with the mean value of 0.21. The emanation factor of the tailings with moisture saturation level over 0.09 was found to be about three times higher than that of the absolutely dry tailings. The empirical relationship obtained between (222)Rn emanation rate and (226)Ra activity concentration of the tailings indicated a significant positive linear correlation (r = 0.95, p < 0.001). This relationship may be useful for quick prediction of radon emanation rate from the backfill material of similar nature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Heavy Tail Behavior of Rainfall Extremes across Germany

    Science.gov (United States)

    Castellarin, A.; Kreibich, H.; Vorogushyn, S.; Merz, B.

    2017-12-01

    Distributions are termed heavy-tailed if extreme values are more likely than would be predicted by probability distributions that have exponential asymptotic behavior. Heavy-tail behavior often leads to surprise, because historical observations can be a poor guide for the future. Heavy-tail behavior seems to be widespread for hydro-meteorological extremes, such as extreme rainfall and flood events. To date there have been only vague hints to explain under which conditions these extremes show heavy-tail behavior. We use an observational data set consisting of 11 climate variables at 1440 stations across Germany. This homogenized, gap-free data set covers 110 years (1901-2010) at daily resolution. We estimate the upper tail behavior, including its uncertainty interval, of daily precipitation extremes for the 1,440 stations at the annual and seasonal time scales. Different tail indicators are tested, including the shape parameter of the Generalized Extreme Value distribution, the upper tail ratio and the obesity index. In a further step, we explore to which extent the tail behavior can be explained by geographical and climate factors. A large number of characteristics is derived, such as station elevation, degree of continentality, aridity, measures for quantifying the variability of humidity and wind velocity, or event-triggering large-scale atmospheric situation. The link between the upper tail behavior and these characteristics is investigated via data mining methods capable of detecting non-linear relationships in large data sets. This exceptionally rich observational data set, in terms of number of stations, length of time series and number of explaining variables, allows insights into the upper tail behavior which is rarely possible given the typical observational data sets available.

  19. Predicting the long term stabilisation of uranium mill tailings

    International Nuclear Information System (INIS)

    Trojacek, J.

    2004-01-01

    The long-term stabilization and remediation of uranium mill tailings ponds is an important task for DIAMO. After uranium mining was stopped, DIAMO has to remediate more then 400 ha of tailings ponds at three locations. It is currently planned to cover the surface with low permeability materials with a slope of approx. 3% to protect the interior of the disposal facility from infiltrating rainwater. This entails to cover the free surface of these ponds with several hundred thousand tons of inert material. As a result of this load, the porewater from the tailings is expelled and the body of the impounded materials consolidates. Consolidation of tailings proceeds irregularly, depending on the internal structure of the tailings layers and on the progress of loading. The surface needs to be recontoured for a long time into the future. The topic of the DIAMO project is to predict and optimise the final surface contour of the tailings pond body, and to determine the time schedule and locations for recontouring work. The K1 tailings pond in Dolni Rozinka (Southern Moravia) is a typical example for such task. The average thickness of the tailings layer is around 25 m and the average porewater contents varies from 25 up to 40%. In the years 1998-99 a PHARE pilot project was undertaken that aimed to predict the quantity and quality of drainage and infiltration waters as a function of time. A new investigation programme (field, laboratory and modelling) has been implemented. The range of material properties and distribution of types of tailings was established. Orientation calculations of the tailings consolidation were made for fine slime zone. The results have shown that significant subsidence of the surface is to be expected after loading with inert material for the construction of an interim cover. (author)

  20. Mine tailings dams: Characteristics, failure, environmental impacts, and remediation

    International Nuclear Information System (INIS)

    Kossoff, D.; Dubbin, W.E.; Alfredsson, M.; Edwards, S.J.; Macklin, M.G.; Hudson-Edwards, K.A.

    2014-01-01

    On a global scale demand for the products of the extractive industries is ever increasing. Extraction of the targeted resource results in the concurrent production of a significant volume of waste material, including tailings, which are mixtures of crushed rock and processing fluids from mills, washeries or concentrators that remain after the extraction of economic metals, minerals, mineral fuels or coal. The volume of tailings is normally far in excess of the liberated resource, and the tailings often contain potentially hazardous contaminants. A priority for a reasonable and responsible mining organization must be to proactively isolate the tailings so as to forestall them from entering groundwaters, rivers, lakes and the wind. There is ample evidence that, should such tailings enter these environments they may contaminate food chains and drinking water. Furthermore, the tailings undergo physical and chemical change after they have been deposited. The chemical changes are most often a function of exposure to atmospheric oxidation and tends to make previously, perhaps safely held contaminants mobile and available. If the tailings are stored under water, contact with the atmosphere is substantially reduced, thereby forestalling oxygen-mediated chemical change. It is therefore accepted practice for tailings to be stored in isolated impoundments under water and behind dams. However, these dams frequently fail, releasing enormous quantities of tailings into river catchments. These accidents pose a serious threat to animal and human health and are of concern for extractive industries and the wider community. It is therefore of importance to understand the nature of the material held within these dams, what best safety practice is for these structures and, should the worst happen, what adverse effects such accidents might have on the wider environment and how these might be mitigated. This paper reviews these factors, covering the characteristics, types and magnitudes

  1. Meeting the challenge - solutions for managing oil sands tailings: report of the fine tailings fundamentals consortium 1989-1995

    International Nuclear Information System (INIS)

    1996-01-01

    The development and demonstration of effective alternatives for the management of fine tailings in the oil sands industry were discussed in a report describing the work of the Fine Tailings Fundamentals Consortium during the period from 1989 to 1995. The final report of the Consortium is a four-volume publication entitled 'Advances in Oil Sands Tailings Research' which is the state-of-the-art reference to key issues in the reclamation of fine tailings. Government regulations now make it the responsibility of industry to integrate the fine tailings into reclaimed landscapes, so that the final landscape is equal in productive capability to the pre-disturbed state. Impressive progress has been made in understanding the formation of fine tailings and in characterizing their properties, much of it through the work of this Consortium. Fundamental research on the clay particles within fine tailings provides a better understanding of how to manage them. Although there is no 'magic bullet', research has demonstrated that an integrated approach incorporating fine tailings with a variety of elements, uplands, lakes and wetlands, offer the best hope for an environmentally sound solution. figs

  2. Predicting arsenic concentrations in porewaters of buried uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Langmuir, D.; Mahoney, J.; MacDonald, A.; Rowson, J.

    1999-10-01

    The proposed JEB Tailings Management Facility (TMF) to be emplaced below the groundwater table in northern Saskatchewan, Canada, will contain uranium mill tailings from McClean Lake, Midwest and Cigar Lake ore bodies, which are high in arsenic (up to 10%) and nickel (up to 5%). A serious concern is the possibility that high arsenic and nickel concentrations may be released from the buried tailings, contaminating adjacent groundwaters and a nearby lake. Laboratory tests and geochemical modeling were performed to examine ways to reduce the arsenic and nickel concentrations in TMF porewaters so as to minimize such contamination from tailings buried for 50 years and longer. The tests were designed to mimic conditions in the mill neutralization circuit (3 hr tests at 25 C), and in the TMF after burial (5--49 day aging tests). The aging tests were run at 50, 25 and 4 C (the temperature in the TMF). In order to optimize the removal of arsenic by adsorption and precipitation, ferric sulfate was added to tailings raffinates having Fe/As ratios of less than 3--5. The acid raffinates were then neutralized by addition of slaked lime to nominal pH values of 7, 8, or 9. Analysis and modeling of the test results showed that with slaked lime addition to acid tailings raffinates, relatively amorphous scorodite (ferric arsenate) precipitates near pH 1, and is the dominant form of arsenate in slake limed tailings solids except those high in Ni and As and low in Fe, in which cabrerite-annabergite (Ni, Mg, Fe(II) arsenate) may also precipitate near pH 5--6. In addition to the arsenate precipitates, smaller amounts of arsenate are also adsorbed onto tailings solids. The aging tests showed that after burial of the tailings, arsenic concentrations may increase with time from the breakdown of the arsenate phases (chiefly scorodite). However, the tests indicate that the rate of change decreases and approaches zero after 72 hrs at 25 C, and may equal zero at all times in the TMF at 4 C

  3. Utilisation of iron ore tailings as aggregates in concrete

    Directory of Open Access Journals (Sweden)

    Francis Atta Kuranchie

    2015-12-01

    Full Text Available Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength were tested. A controlled mix of concrete was also prepared in similar way using conventional materials and the results were compared with the tailings concrete. It was found that the iron ore tailings may be utilised for complete replacement for conventional aggregates in concrete. The iron ore tailings aggregates concrete exhibited a good mechanical strength and even in the case of compressive strength, there was an improvement of 11.56% over conventional aggregates concrete. The indirect tensile strength did not improve against the control mix due high content of fines in the tailings aggregates but showed 4.8% improvement compared with the previous study where the conventional fine aggregates was partially replaced by 20% with iron ore tailings.

  4. Quasi-steady state aerodynamics of the cheetah tail.

    Science.gov (United States)

    Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

    2016-08-15

    During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. © 2016. Published by The Company of Biologists Ltd.

  5. Impact of flocculation on flotation tailing's hydro-cycloning properties

    Directory of Open Access Journals (Sweden)

    Knežević Dinko N.

    2014-01-01

    Full Text Available Research results of hydro-cycloning of flocculated and non-flocculated flotation tailing from the lead and zinc open pit mine 'Suplja stijena', Sula - Montenegro have been shown in this paper. Reason for this research was finding conditions in order to separate fraction that is suitable for embankment erection. Flotation tailings has been tested in the very state that it goes out from the flotation process and tailings which is flocculated by anionic flocculant. The object was to determine the impact of flocculation on properties of hydro-cycloning products and disposal process. In hydro-cycloning process greater underflow mass is being separated with non-flocculated tailing. Values of geomechanical parameters are significantly different, especially hydro-cyclone's underflow. All geomechanical parameters of hydro-cyclone's underflow are suitable for erecting embankment which shall be made from non-flocculated tailing. Underflow drainage of non-flocculated tailing is faster while overflow drainage is slower and problematic with both tailings.

  6. Quasi-steady state aerodynamics of the cheetah tail

    Directory of Open Access Journals (Sweden)

    Amir Patel

    2016-08-01

    Full Text Available During high-speed pursuit of prey, the cheetah (Acinonyx jubatus has been observed to swing its tail while manoeuvring (e.g. turning or braking but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.

  7. Estimation of bitumen and clay content in fine tailings

    International Nuclear Information System (INIS)

    Motta Cabrera, S.C.; Bryan, J.; Kantzas, A.

    2007-01-01

    Fine tailings are the components of tailings ponds and the by-product of the oil sand extraction process, consisting mostly of water with small amounts of bitumen, sand, silts and clays. Because of the large volumes of tailings, an important environmental and production process issue involves the reduction of the remaining bitumen in the tailings stream. This paper presented the results of a study that used low field nuclear magnetic resonance (NMR) in order to estimate the bitumen, clay and water content of synthetic tailings samples. NMR is a non-destructive technique that is utilized to determine compositions of oil and brine emulsions and the viscosity of heavy oil and bitumen as well as in reservoir characterization, measuring properties such as permeability, porosity, mobile and immobile fluids, and fluid saturations. The study prepared and tested numerous samples with variable water, bitumen, sand and clay concentrations in the NMR tool under ambient conditions. Two qualities of water and bitumen were used to prepare the synthetic samples. Each type of water and bitumen was analyzed as a single substance and in a mixture with the typical solids found in tailings composition. These included kaolinite, illite, sodium montmorillonite and sand. These synthetic samples were analyzed using different mixing configurations, as a function of time and in two different NMR tools. It was concluded that NMR is a potential application for on-line determination of tailings streams composition. 18 refs., 3 tabs., 17 figs

  8. Subsurface variations in arsenic mineralogy and geochemistry following long-term weathering of gold mine tailings

    International Nuclear Information System (INIS)

    DeSisto, Stephanie L.; Jamieson, Heather E.; Parsons, Michael B.

    2016-01-01

    Variations in arsenic (As) mineralogy and geochemical controls on its mobility were evaluated in subsurface tailings at the historical Montague and Goldenville mine sites in Nova Scotia, Canada. Tailings at these sites contain some of the highest As concentrations in Nova Scotia and are located in close proximity to local communities. Pore water in the subsurface tailings is characterized by circumneutral to alkaline pH (6.2 to 8.7) and mildly reducing to oxidizing redox conditions (+130 mV to +347 mV). Bulk chemistry, scanning electron microscopy, and synchrotron micro-X-ray diffraction analyses showed As mineral hosts differ with depth. The deepest tailings (max. 2 m) are in direct contact with partially decomposed vegetation, which supports reducing conditions and the precipitation of authigenic As and Fe sulfides. Under reducing conditions, dissolved As concentrations are also controlled by desorption of As from dissolution of Fe and Mn oxides and the sorption or co-precipitation of As with carbonates. These geochemical controls differ from those influencing dissolved As concentrations under oxidizing conditions. In the near surface, As mobility is controlled by oxidative dissolution of primary arsenopyrite, precipitation of secondary Fe arsenates, Fe oxyhydroxides and Mn oxides, secondary Ca-Fe arsenates, and sorption onto Fe oxyhydroxides and gangue minerals. Some of these mineral species are stable under different conditions yet occur in close association, indicating the importance of microenvironments. The results of this study show that the weathering characteristics of these tailings vary with depth, leading to the formation of new As hosts that are distinct from those observed in the near surface. Identification of these As hosts provides an understanding of current controls on As mobility and has implications for future reprocessing and/or remediation efforts. - Highlights: • Subsurface mineralogy does not reflect surface tailings end

  9. Making a Magnetorheological Fluid from Mining Tailings

    Science.gov (United States)

    Quitian, G.; Saldarriaga, W.; Rojas, N.

    2017-12-01

    We have obtained magnetite mining tailings and used it to fabricate a magnetorheological fluid (MRF). Mineralogical and morphological characteristics were determined using X-ray diffraction (XRD) and energy dispersive spectrometry (EDS), as well as size and geometry for the obtained magnetite. Finally, the fabricated MRF was rheologically characterized in a device attached to a rheometer. The application of a magnetic field of 0.12 Tesla can increase the viscosity of the MRF by more than 400 pct. A structural formation should occur within the fluid by a reordering of particles into magnetic columns, which are perpendicular to the flow direction. These structures give the fluid an increased viscosity. As the magnetic field increases, the structure formed is more resistant, resulting in an increased viscosity. One can appreciate that with a value equal to or less than 0.06 Tesla of applied magnetic field, many viscosity values associated with the work area of the oils can be achieved (0.025 and 0.34 Pa s).

  10. Flocculation of flotation tailings using thermosensitive polymers

    Directory of Open Access Journals (Sweden)

    Bogacz Wojciech

    2017-09-01

    Full Text Available The key feature of thermosensitive polymers is the reversible transition between the hydrophilic and hydrophopic forms depending on the temperature. Although the main research efforts are focused on their application in different kinds of drug delivery systems, this phenomenon also allows one to precisely control the stability of solid-liquid dispersions. In this paper research on the application of poly(N-isopropylacrylamide copolymers in processing of minerals is presented. In the experiments tailings from flotation plant of one of the coal mines of Jastrzębska Spółka Węglowa S.A. (Poland were used. A laser particle sizer Fritsch Analysette 22 was used in order to determine the Particle Size Distribution (PSD. It was proved that there are some substantial issues associated with the application of thermosensitive polymers in industrial practice which may exclude them from the common application. High salinity of suspension altered the value of Lower Critical Solution Temperature (LCST. Moreover, the co-polymers used in research proved to be efficient flocculating agents without any temperature rise. Finally, the dosage needed to achieve steric stabilization of suspension was greatly beyond economic justification.

  11. Integrated oil sands tailings pond water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. [Saskatchewan Research Council, Saskatoon, SK (Canada)

    2010-07-01

    This PowerPoint presentation discussed research currently being conducted to treat oil sands tailings pond water (TPW). The treatment of TPW is challenged by the high level of naphthenic acids (NAs), the slow settling rate of fine particulate materials, and the complex chemistry of the water. The treatment process consisted of bioflocculation, sludge blanket assisted clarification, ozonation, and oil sands coke assisted hybrid biodegradation. The aggregation and adsorption process bound small particles and cells together while also ensuring the passive uptake of pollutants using microbial masses. The mixed liquor then passed through a sludge blanket to ensure enhanced particle capture. An ozonation process was used to increase the biodegradability of the TPW as well as to increase the biodegradability of the residual NAs after ozonation. The process used a hybrid bioreactor that consisted of both suspended and fixed microbial communities. The coke served as a biofilm carrier for the waste. Further studies are being conducted to investigate the efficiency and capability of the process. tabs., figs.

  12. Tail Risk Constraints and Maximum Entropy

    Directory of Open Access Journals (Sweden)

    Donald Geman

    2015-06-01

    Full Text Available Portfolio selection in the financial literature has essentially been analyzed under two central assumptions: full knowledge of the joint probability distribution of the returns of the securities that will comprise the target portfolio; and investors’ preferences are expressed through a utility function. In the real world, operators build portfolios under risk constraints which are expressed both by their clients and regulators and which bear on the maximal loss that may be generated over a given time period at a given confidence level (the so-called Value at Risk of the position. Interestingly, in the finance literature, a serious discussion of how much or little is known from a probabilistic standpoint about the multi-dimensional density of the assets’ returns seems to be of limited relevance. Our approach in contrast is to highlight these issues and then adopt throughout a framework of entropy maximization to represent the real world ignorance of the “true” probability distributions, both univariate and multivariate, of traded securities’ returns. In this setting, we identify the optimal portfolio under a number of downside risk constraints. Two interesting results are exhibited: (i the left- tail constraints are sufficiently powerful to override all other considerations in the conventional theory; (ii the “barbell portfolio” (maximal certainty/ low risk in one set of holdings, maximal uncertainty in another, which is quite familiar to traders, naturally emerges in our construction.

  13. Summary of the engineering assessment of inactive uranium mill tailings

    International Nuclear Information System (INIS)

    1981-07-01

    The Grand Junction site has been reevaluated in order to revise the october 1977 engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Grand Junction, Colorado. This engineering assessment has included the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative corrective actions. Radon gas released from the 1.9 million tons of tailings at the Grand Junction site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation are also factors. The eight alternative actions presented herein range from millsite and off-site decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings to remote disposal sites and decontamination of the tailings site (Option II through VIII). Cost estimates for the eight options range from about $10,200,000 for stabilization in-place to about $39,500,000 for disposal in the DeBeque area, at a distance of about 35 mi, using transportation by rail. If transportation to DeBeque were by truck, the cost is estimated to be about $41,900,000. Three prinicpal alternatives for the reprocessing of the Grand Junction tailings were examined: (a) heap leaching; (b) treatment at an existing mill; and (c) reprocessing at a new conventional mill constructed for tailings reprocessing. The cost of the uranium recovered would be about $200/lb by heap leach and $150/lb by conventional plant processes. The spot market price for uranium was $25/lb early in 1981. Therefore, reprocessing the tailings for uranium recovery appears not to be economically attractive

  14. Arsenic readily released to pore waters from buried mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, John [Hydrologic Consultants, Inc., 143 Union Blvd., Suite 525, Lakewood, CO 80228 (United States)]. E-mail: jmahoney@hcico.com; Langmuir, Donald [Hydrochem Systems Corp., P.O. Box 17090, Golden, CO 80402 (United States); Gosselin, Neil [Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Way, Regina, SK, S4S 0A2 (Canada); Rowson, John [COGEMA Resources, Inc., P.O. Box 9204, Saskatoon, SK, S7K 3X5 (Canada)

    2005-05-15

    At the McClean Lake Operation in the Athabasca Basin of northern Saskatchewan, the untreated acid raffinate solutions associated with U mill tailings contain up to 700 mg/L dissolved As. To reduce the concentration of As and other contaminants in acid tailing slurries at the JEB mill at McClean Lake, ferric sulfate may be added to the acid raffinates to assure that their molar Fe/As ratio equals or exceeds 3. Tailings slurries are then neutralized with lime to pH 4, and subsequently to pH 7-8. The neutralized tailings contain minerals from the original ore, which are chiefly quartz, illite, kaolinite and chlorite, and precipitated (secondary) minerals that include gypsum, scorodite, annabergite, hydrobasaluminite and ferrihydrite. Most of the As is associated with the secondary arsenate minerals, scorodite and annabergite. However, a few percent is adsorbed and/or co-precipitated, mainly by ferrihydrite. Of major concern to provincial and federal regulators is the risk that significant amounts of As might be released from the tailings to pore waters after their subaqueous disposal in the tailings management facility. A laboratory study was performed to address this issue, measuring readily desorbed As using a method known as equilibrium partitioning in closed systems (EPICS). The EPICS method was selected because it employs a leaching solution that, except for its As concentration, is identical in composition to the neutralized raffinate in contact with the tailings. Laboratory experiments and modeling results demonstrated that the As that could be readily released to pore waters is about 0.2% of the total As in the tailings. Long-term, such releases may contribute no more than a few mg/L of dissolved As to tailings pore waters.

  15. Arsenic readily released to pore waters from buried mill tailings

    International Nuclear Information System (INIS)

    Mahoney, John; Langmuir, Donald; Gosselin, Neil; Rowson, John

    2005-01-01

    At the McClean Lake Operation in the Athabasca Basin of northern Saskatchewan, the untreated acid raffinate solutions associated with U mill tailings contain up to 700 mg/L dissolved As. To reduce the concentration of As and other contaminants in acid tailing slurries at the JEB mill at McClean Lake, ferric sulfate may be added to the acid raffinates to assure that their molar Fe/As ratio equals or exceeds 3. Tailings slurries are then neutralized with lime to pH 4, and subsequently to pH 7-8. The neutralized tailings contain minerals from the original ore, which are chiefly quartz, illite, kaolinite and chlorite, and precipitated (secondary) minerals that include gypsum, scorodite, annabergite, hydrobasaluminite and ferrihydrite. Most of the As is associated with the secondary arsenate minerals, scorodite and annabergite. However, a few percent is adsorbed and/or co-precipitated, mainly by ferrihydrite. Of major concern to provincial and federal regulators is the risk that significant amounts of As might be released from the tailings to pore waters after their subaqueous disposal in the tailings management facility. A laboratory study was performed to address this issue, measuring readily desorbed As using a method known as equilibrium partitioning in closed systems (EPICS). The EPICS method was selected because it employs a leaching solution that, except for its As concentration, is identical in composition to the neutralized raffinate in contact with the tailings. Laboratory experiments and modeling results demonstrated that the As that could be readily released to pore waters is about 0.2% of the total As in the tailings. Long-term, such releases may contribute no more than a few mg/L of dissolved As to tailings pore waters

  16. Preparation of nano-iron oxide red pigment powders by use of cyanided tailings

    International Nuclear Information System (INIS)

    Li Dengxin; Gao Guolong; Meng Fanling; Ji Chong

    2008-01-01

    On one hand, cyanided tailings are one kind of pollutants. On the other hand, they contain a lot of valuable elements. So utilization of them can bring social and environmental benefits. In this paper, cyanided tailings were used to prepare nano-iron oxide red pigment powders by an ammonia process with urea as precipitant. At first, cyanided tailings were oxidized by nitric acid. Then, the oxidizing mixture was separated into solid and liquid parts. The liquid mixture was reduced by scrap iron and the impurity of it was removed by use of NH 3 .H 2 O. Then, the seed crystal of γ-FeOOH was obtained, when the pure liquid reacted with ammonia liquid at the selected experimental conditions. At last, nano-iron oxide red pigment powders were prepared. The structure, morphology and size distribution of seed crystal and iron oxide red were characterized systematically by means of X-ray diffraction (XRD), transmission electron microscope (TEM) and laser particle size analyzer (LPSA). The results revealed that typical iron oxide nanoparticles were α-Fe 2 O 3 with particle size of 50-70 nm. Furthermore, the factors that affected the hue and quality of the seed crystal and iron oxide red pigment were also discussed

  17. Influence of HMW tail chains on the structural evolution of HDPE induced by second melt penetration.

    Science.gov (United States)

    Zhu, Chun-Xia; Xia, Xiao-Chao; Huang, Yan-Hao; Xie, Dan-Dan; Chen, Rui; Yang, Ming-Bo

    2017-07-21

    It is widely accepted that the role of the high molecular weight (HMW) component is cooperative in shear-induced crystallization, owing to entanglements among long chains. However, this paper demonstrates that the HMW component has a novel effect on structural evolution during the process of multi-melt multi-injection molding (M 3 IM), organized as follows. First, the appropriate HDPE system with an incremental concentration of HMW tails was established. Second, the crystalline morphologies and orientation behaviors of the M 3 IM samples were characterized using a combination of scanning electron microscopy (SEM) and two-dimensional small angle X-ray scattering (2D-SAXS), and these suggested that the amount of shish-kebabs was not monotonically promoted with an increasing content of HMW tails but tended to reduce at a certain value. Third, in order to explain this phenomenon, the special temperature and shear profiles of M 3 IM were depicted subsequently, and finally the mechanism of hierarchical structure formation with the influence of various amounts of HMW tail chains was discussed, based on the classical rheological viewpoint.

  18. Ultra-differentiation of Sperm Tail of Lesser Egyptian Jerboa, Jaculus jaculus (Family: Dipodidae

    Directory of Open Access Journals (Sweden)

    Osama M. Sarhan

    2016-01-01

    Full Text Available In the present study, events of sperm tail differentiation in Lesser Egyptian Jerboa, Jaculus jaculus were studied for the first time. Generally, stages of sperm tail differentiation are more or less similar to that described by other studies in other rodents. In the present species, special structures were observed. These structures include, first: the formation of a hollow large unit of microtubules that appears to surround the nuclear envelope at its equatorial plane. The manchette microtubules (MMs are re-oriented toward the longitudinal direction and attached along hollow large unit of microtubules. Second, the formation of perinuclear space filled with an electron-translucent substance surrounds the posterior third of the developing nucleus. Third, the nuclear fossa and the connecting piece were inserted in the ventrodorsal region of the nucleus. Fourth, the fibrous sheath (FS is formed of dextral spiral fibrous ribs. Finally, the sperm tail of the present species has a single outer FS, however, other rodents, having additional inner fibrous units, between the outer FS and the inner developing axoneme.

  19. Hydrology of Quirke and Panel uranium tailings basins

    International Nuclear Information System (INIS)

    King, R.M.; MacPhie, L.

    1991-11-01

    The research project described by this report provides the AECB with an independent assessment of the 'saturated tailings concept' for the decommissioning of tailing areas at the Rio Algom Quirke and Panel uranium mines near Elliot Lake in Northern Ontario. Hydrologic and hydraulic modelling for each facility showed the interrelation between the design of the water-level control facilities and the water levels in each cell for design flood and extreme low-flow conditions, taking into account all water-balance components. The estimate of seepage rates through the tailings mass is identified as a critical issue

  20. UMTRAP research on cover design for uranium mill tailings

    International Nuclear Information System (INIS)

    Rogers, V.C.; Nielson, K.K.

    1984-01-01

    As a result of the UMTRAP research on radon attenuation and tailings cover design, the basis and general procedures are available for designing covers for uranium tailings piles to meet present criteria for radon emissions. The general procedures involve assessment of the radon source strength of the tailings, definition of candidate cover materials, assessment of their moisture retention and radon diffusion properties, computing the required thicknesses of these materials, comparing costs, and evaluating long-term performance criteria. Final selection of the cover design must assure adequate long-term performance and radon retention as first priority, and keep costs to a minimum in achieving this goal

  1. Dam-break studies for mine tailings impoundments

    International Nuclear Information System (INIS)

    Jeyapalan, J.K.

    1982-01-01

    This paper describes simple procedures for performing dam-break analyses. Tailings from dam failures usually liquefy and flow for substantial distances as a viscous fluid. The prediction of the possible extent of flow slide movement is illustrated using two case histories. Topics considered include the flow behavior of liquefied talings, dimensionsless numbers for mine tailings and associated flow regimes, laminar flow, and turbulent flow. The potential inundation regions downstream of mine tailings dams are assessed. It is concluded that instances of flow slides of mine waste embankments indicate that the failure of these structures has considerable potential for damage to life and property in many cases

  2. Band tailing and efficiency limitation in kesterite solar cells

    Science.gov (United States)

    Gokmen, Tayfun; Gunawan, Oki; Todorov, Teodor K.; Mitzi, David B.

    2013-09-01

    We demonstrate that a fundamental performance bottleneck for hydrazine processed kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells with efficiencies reaching above 11% can be the formation of band-edge tail states, which quantum efficiency and photoluminescence data indicate is roughly twice as severe as in higher-performing Cu(In,Ga)(S,Se)2 devices. Low temperature time-resolved photoluminescence data suggest that the enhanced tailing arises primarily from electrostatic potential fluctuations induced by strong compensation and facilitated by a lower CZTSSe dielectric constant. We discuss the implications of the band tails for the voltage deficit in these devices.

  3. Heavy-tailed distributions and robustness in economics and finance

    CERN Document Server

    Ibragimov, Marat; Walden, Johan

    2015-01-01

    This book focuses on general frameworks for modeling heavy-tailed distributions in economics, finance, econometrics, statistics, risk management and insurance. A central theme is that of (non-)robustness, i.e., the fact that the presence of heavy tails can either reinforce or reverse the implications of a number of models in these fields, depending on the degree of heavy-tailedness. These results motivate the development and applications of robust inference approaches under heavy tails, heterogeneity and dependence in observations. Several recently developed robust inference approaches are discussed and illustrated, together with applications.

  4. Putting tailings in perspective radiologically, environmentally and managerially

    International Nuclear Information System (INIS)

    Shreve, J.D. Jr.

    1978-01-01

    Present management of uranium mill tailings is sophisticated compared with recounted practises of 15 to 20 years ago. Further improvements while possible and wanted should not be rushed. Many factors enter. The paper suggests routes to selecting radiological protective standards, elucidates the site-specific and process-specific nature of tailings control, provides comparative references on source terms of radon, uranium, thorium and radium, defends the need for multiple control and for plan endorsement in perpetuity once approval is granted, except as improved control at lesser cost proves doable. One idea is proffered for reducing tailings mass to one-third that accumulated by current practises

  5. Heat Recovery From Tail Gas Incineration To Generate Power

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, Tarek

    2010-09-15

    Many industrial processes result in tail gas wastes that must be flared or incinerated to abide with environmental guidelines. Tail gas incineration occurs in several chemical processes resulting in high-temperature exhaust gas that simply go to the stack, thus wasting all that valuable heat! This paper discusses useful heat recovery and electric power generation utilizing available heat in exhaust gas from tail gas incinerators. This heat will be recovered in a waste-heat recovery boiler that will produce superheated steam to expand in a steam turbine to generate power. A detailed cost estimate is presented.

  6. Price Tails in the Smith and Farmer's Model

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    2008-01-01

    Roč. 15, č. 25 (2008), s. 31-40 ISSN 1212-074X R&D Projects: GA ČR GA402/07/1113; GA ČR(CZ) GA402/06/1417 Institutional research plan: CEZ:AV0Z10750506 Keywords : limit order market * continuous double auction * price increments * fat tails * tail exponent Subject RIV: AH - Economics http://library.utia.cas.cz/separaty/2008/E/smid-price tails in the smith and farmer's model.pdf

  7. A Comparison of Tail Behaviour of Stock Market Returns

    Directory of Open Access Journals (Sweden)

    Echaust Krzysztof

    2014-06-01

    Full Text Available Most investors believe that left tails of the stock returns distribution are heavier than the right ones. It is a natural consequence of crashes perception as much more turbulent than the booms. Crashes develop in shorter time intervals than booms and changes of prices are significantly bigger. This paper focuses on the extreme behavior of stock market returns. The differences in the tails thickness of distribution are negligible. Its main result is that the differences between tails have been found in the clustering of extremes, especially during the crash of 2007-2009.

  8. Uranium mill tailings storage, use, and disposal problems

    International Nuclear Information System (INIS)

    Hendricks, D.W.

    1977-01-01

    Solid and liquid residues (tailings) containing substantial quantities of naturally occurring radionuclides are produced and stored at all US uranium mill sites. These radioactive wastes are a potential health hazard with the degree of hazard depending largely on the tailings management practices at the individual sites. The principal pathways of potential radiation exposure to man are discussed. A description is presented of some past and current tailings storage practices together with a description of some of the possible problems associated with various stabilization and disposal options. 16 figures

  9. Neural stem/progenitor cells are activated during tail regeneration in the leopard gecko (Eublepharis macularius).

    Science.gov (United States)

    Gilbert, E A B; Vickaryous, M K

    2018-02-01

    As for many lizards, the leopard gecko (Eublepharis macularius) can self-detach its tail to avoid predation and then regenerate a replacement. The replacement tail includes a regenerated spinal cord with a simple morphology: an ependymal layer surrounded by nerve tracts. We hypothesized that cells within the ependymal layer of the original spinal cord include populations of neural stem/progenitor cells (NSPCs) that contribute to the regenerated spinal cord. Prior to tail loss, we performed a bromodeoxyuridine pulse-chase experiment and found that a subset of ependymal layer cells (ELCs) were label-retaining after a 140-day chase period. Next, we conducted a detailed spatiotemporal characterization of these cells before, during, and after tail regeneration. Our findings show that SOX2, a hallmark protein of NSPCs, is constitutively expressed by virtually all ELCs before, during, and after regeneration. We also found that during regeneration, ELCs express an expanded panel of NSPC and lineage-restricted progenitor cell markers, including MSI-1, SOX9, and TUJ1. Using electron microscopy, we determined that multiciliated, uniciliated, and biciliated cells are present, although the latter was only observed in regenerated spinal cords. Our results demonstrate that cells within the ependymal layer of the original, regenerating and fully regenerate spinal cord represent a heterogeneous population. These include radial glia comparable to Type E and Type B cells, and a neuronal-like population of cerebrospinal fluid-contacting cells. We propose that spinal cord regeneration in geckos represents a truncation of the restorative trajectory observed in some urodeles and teleosts, resulting in the formation of a structurally distinct replacement. © 2017 Wiley Periodicals, Inc.

  10. HARD X-RAY TAIL DISCOVERED IN THE CLOCKED BURSTER GS 1826–238

    Energy Technology Data Exchange (ETDEWEB)

    Rodi, J.; Jourdain, E.; Roques, J. P., E-mail: jrodi@irap.omp.eu [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France)

    2016-02-01

    The low-mass X-ray binary (LMXB) neutron star (NS) GS 1826–238 was discovered by Ginga in 1988 September. Due to the presence of quasi-periodicity in the type I X-ray burst rate, the source has been a frequent target of X-ray observations for almost 30 years. Though the bursts were too soft to be detected by INTEGRAL/SPI, the persistent emission from GS 1826–238 was detected over 150 keV during the ∼10 years of observations. Spectral analysis found a significant high-energy excess above a Comptonization model that is well fit by a power law, indicating an additional spectral component. Most previously reported spectra with hard tails in LMXB NS have had an electron temperature of a few keV and a hard tail dominating above ∼50 keV with an index of Γ ∼ 2–3. GS 1826–238 was found to have a markedly different spectrum with kT{sub e} ∼ 20 keV and a hard tail dominating above ∼150 keV with an index of Γ ∼ 1.8, more similar to black hole X-ray binaries. We report on our search for long-term spectral variability over the 25–370 keV energy range and on a comparison of the GS 1826–238 average spectrum to the spectra of other LMXB NSs with hard tails.

  11. Photonic Crystals with an Eye Pattern Similar to Peacock Tail Feathers

    Directory of Open Access Journals (Sweden)

    Minghui Wang

    2016-08-01

    Full Text Available A facile fabrication of photonic crystals (PCs with an eye pattern similar to peacock tail feathers has been demonstrated by self-assembly of colloidal particles in a sandwich mode. The sandwich mode is formed by superhydrophilic flat substrate sandwiching the poly(styrene-methyl methacrylate-arylic acid (Poly(St-MMA-AA latex suspension (2 wt% by the hydrophobic one. The patterns are characterized by optical microscopy images, reflection spectra, and the relative scanning electronic microscope images. This work will provide beneficial help for the understanding of the self-assembly process of colloidal crystals.

  12. Limit cycle behaviour of the bump-on-tail and ion-acoustic instability

    International Nuclear Information System (INIS)

    Janssen, P.A.E.M.; Rasmussen, J.J.

    1980-12-01

    The nonlinear dynamics of the bump-on-tail and current-driven ion-acoustic instability is considered. The eigenmodes have discrete k because of finite periodic boundary conditions. Increasing a critical parameter (the number density and the electron drift velocity respectively) above its neutral stable value by a small fractional amount Δ 2 , one mode becomes unstable. The nonlinear dynamics of the unstable mode is determined by means of the multiple time scale method. Usually, limit cycle behaviour is found. A short comparison with quasi-linear theory is given, and the results are compared with experiment. (Auth.)

  13. Conformational analysis of the partially disordered measles virus N(TAIL)-XD complex by SDSL EPR spectroscopy.

    Science.gov (United States)

    Kavalenka, Aleh; Urbancic, Iztok; Belle, Valérie; Rouger, Sabrina; Costanzo, Stéphanie; Kure, Sandra; Fournel, André; Longhi, Sonia; Guigliarelli, Bruno; Strancar, Janez

    2010-03-17

    To characterize the structure of dynamic protein systems, such as partly disordered protein complexes, we propose a novel approach that relies on a combination of site-directed spin-labeled electron paramagnetic resonance spectroscopy and modeling of local rotation conformational spaces. We applied this approach to the intrinsically disordered C-terminal domain of the measles virus nucleoprotein (N(TAIL)) both free and in complex with the X domain (XD, aa 459-507) of the viral phosphoprotein. By comparing measured and modeled temperature-dependent restrictions of the side-chain conformational spaces of 12 SL cysteine-substituted N(TAIL) variants, we showed that the 490-500 region of N(TAIL) is prestructured in the absence of the partner, and were able to quantitatively estimate, for the first time to our knowledge, the extent of the alpha-helical sampling of the free form. In addition, we showed that the 505-525 region of N(TAIL) conserves a significant degree of freedom even in the bound form. The latter two findings provide a mechanistic explanation for the reported rather high affinity of the N(TAIL)-XD binding reaction. Due to the nanosecond timescale of X-band EPR spectroscopy, we were also able to monitor the disordering in the 488-525 region of N(TAIL), in particular the unfolding of the alpha-helical region when the temperature was increased from 281 K to 310 K. Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Production of sorption functional media (SFM) from clinoptilolite tailings and its performance investigation in a biological aerated filter (BAF) reactor

    International Nuclear Information System (INIS)

    Feng, Yan; Qi, Jingyao; Chi, Liying; Wang, Dong; Wang, Zhaoyang; Li, Ke; Li, Xin

    2013-01-01

    Highlights: ► Sorption functional media (SFM) were prepared using zeolite tailings. ► Two upflow BAFs were applied to treat municipal wastewater. ► SFM BAF brought a relative superiority to haydite reactor. ► SFM BAF has a stronger adaptability to low temperature (6–11°C) for NH 3 -N removal. ► The application provided a promising way in zeolite tailings utilization. -- Abstract: The few reuse and large stockpile of zeolite tailings led to a series of social and environmental problems. This study investigated the possibility of using the zeolite tailings as one of principal raw materials to prepare sorption functional media (SFM) by a high temperature sintering process. The SFM was used to serve as a biomedium in a biological aerated filter (BAF) reactor for domestic wastewater treatment, and its purification performance was examined. The physical, chemical and sorption properties of SFM were also determined. The microstructure of the SFM was analyzed by scanning electron microscopy (SEM). Results revealed that: (1) zeolite tailings could be used to produce the SFM under the optimal sintering parameters; (2) the sorption and desorption isotherm of ammonia nitrogen on SFM could be well described by the Langmuir formula; (3) in terms of removing organic matter, ammonia nitrogen, turbidity and colourity, the performance of the biofilter with SFM was superior to that with haydite; and (4) SFM BAF has a stronger adaptability to low temperature (6–11 °C) for NH 3 -N removal compared to haydite BAF. Therefore, the SFM produced from the zeolite tailings was suitable to serve as the biomedium in the domestic wastewater treatment

  15. Filtration of Oil-furnace Carbon Black Dust Particles from the Tail Gases by Filter Bags With PTFE Membrane

    Directory of Open Access Journals (Sweden)

    Čuzela, D.

    2010-01-01

    Full Text Available During the industrial production of oil furnace carbon black, tail gases containing oil-furnace carbon black dust particles are emitted to the atmosphere. In the carbon black plant, Petrokemija d. d., there are six exhaust stacks for tail gases. Each of them has installed process equipment for cleaning tail gases. Efficiency of cleaning mainly depends on equipment construction and cleaning technology. The vicinity of the town, quality of the air in the region of Kutina, regarding floating particles PM10, and corporate responsibility for further enviromental improvement, imposes development of new methods that will decrease the emmision of oil-furnace carbon black dust particles in the air. Combining centrifugal percipitator and filter, special construction of cyclofilter for filtration of oil-furnace carbon black dust particles from tail gases by using PTFE (polytetrafluoroethylene membrane filter bags, was designed. Developed filtration technique provides η = 99.9 % efficiency of filtration. Construction part of the filter contains the newest generation of PTFE membrane filter bags with the ability of jet pulse cleaning. Using the PTFE membrane filter bags technology, filtration efficiency for oil-furnace carbon black dust particles in tail gases of maximum γ=5mgm-3can be achieved. The filtration efficiency was monitored continuously measuring the concentration of the oil-furnace carbon black dust particles in the tail gases with the help of in situ electronic probe. The accomplished filtration technology is the base for the installation of the PTFE membrane filter bags in the main operation filters which will provide better protection of the air in the town of Kutina against floating particles PM10.

  16. Uranium Mill Tailings Remedial Action 1993 Roadmap

    International Nuclear Information System (INIS)

    1993-01-01

    The 1993 Roadmap for the Uranium Mill Tailings Remedial Action (UMTRA) Project office is a tool to assess and resolve issues. The US Department of Energy (DOE) UMTRA Project Office uses the nine-step roadmapping process as a basis for Surface and Groundwater Project planning. This is the second year the Roadmap document has been used to identify key issues and assumptions, develop logic diagrams, and outline milestones. This document is a key element of the DOE planning process. A multi-interest group used the nine-step process to focus on issues, root cause analysis and resolutions. This core group updated and incorporated comments on the basic assumptions, then used these assumptions to identify issues. The list of assumptions was categorized into the following areas: institutional, regulatory compliance, project management, human resource requirements, and other site-specific assumptions. The group identified 10 issues in the analysis phase. All of the issues are ranked according to importance. The number one issue from the 1992 Roadmap, ''Lack of sufficient human resources,'' remained the number one issue in 1993. The issues and their ranking are as follows: Lack of sufficient human resources; increasing regulatory requirements; unresolved groundwater issues; extension of UMTRCA through September 30, 1998; lack of post-UMTRA and post-cell closure policies; unpredictable amounts and timing of Federal funding; lack of regulatory compliance agreements; problem with states providing their share of remedial action costs; different interests and priorities among participants; and technology development/transfer. The issues are outlined and analyzed in detail in Section 8.0, with a schedule for resolution of these issues in Section 9.0

  17. Probabilistic calculation of dose commitment from uranium mill tailings

    International Nuclear Information System (INIS)

    1983-10-01

    The report discusses in a general way considerations of uncertainty in relation to probabilistic modelling. An example of a probabilistic calculation applied to the behaviour of uranium mill tailings is given

  18. Jump Tails, Extreme Dependencies, and the Distribution of Stock Returns

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Viktor

    We provide a new framework for estimating the systematic and idiosyncratic jump tail risks in financial asset prices. The theory underlying our estimates are based on in-fill asymptotic arguments for directly identifying the systematic and idiosyncratic jumps, together with conventional long...... market portfolio, we find that the distributions of the systematic and idiosyncratic jumps are both generally heavy-tailed and not necessarily symmetric. Our estimates also point to the existence of strong dependencies between the market-wide jumps and the corresponding systematic jump tails for all...... of the stocks in the sample. We also show how the jump tail dependencies deduced from the high-frequency data together with the day-to-day temporal variation in the volatility are able to explain the “extreme” dependencies vis-a-vis the market portfolio....

  19. Sandia's activities in uranium mill tailings remedial action

    International Nuclear Information System (INIS)

    Neuhauser, S.

    1980-01-01

    The Uranium Mill Tailings Radiation Control Act of 1978 requires that remedial action be taken at over 20 inactive uranium mill tailings sites in the United States. Standards promulgated by the EPA under this act are to be the operative standards for this activity. Proposed standards must still undergo internal review, public comment, and receive Nuclear Regulatory Commission concurrence before being finalized. Briefly reviewed, the standards deal separately with new disposal sites (Part A) and cleanup of soil and contaminated structures at existing locations (Part B). In several cases, the present sites are felt to be too close to human habitations or to be otherwise unacceptably located. These tailings will probably be relocated. New disposal sites for relocated tailings must satisfy certain standards. The salient features of these standards are summarized

  20. Risk Management - Variance Minimization or Lower Tail Outcome Elimination

    DEFF Research Database (Denmark)

    Aabo, Tom

    2002-01-01

    on future cash flows (the budget), while risk managers concerned about costly lower tail outcomes will hedge (considerably) less depending on the level of uncertainty. A risk management strategy of lower tail outcome elimination is in line with theoretical recommendations in a corporate value......This paper illustrates the profound difference between a risk management strategy of variance minimization and a risk management strategy of lower tail outcome elimination. Risk managers concerned about the variability of cash flows will tend to center their hedge decisions on their best guess......-adding perspective. A cross-case study of blue-chip industrial companies partly supports the empirical use of a risk management strategy of lower tail outcome elimination but does not exclude other factors from (co-)driving the observations....

  1. Long-term ecological behaviour of abandoned uranium mill tailings

    International Nuclear Information System (INIS)

    Kalin, Margarete

    1984-12-01

    Semi-aquatic and terrestrial areas on abandoned or inactive uranium mill tailings in Ontario were studied in order to identify the growth characteristics of the naturally invading species dominating these areas. Semi-aquatic areas of tailings sites have been invaded by cattails. These species formed wetland communities which varied in size, but all were essentially monocultures of Typha latifolia, T. angustifolia, or of the hybrids T. glauca. Sedges, Scripus cyperinus (wool-grass) and Phragmites australis (reed-grass), were found in transition zones between the cattail stand and the dry section of the tailings site. The expansion of the cattail stands appeared to be controlled by the hydrological conditions on the site, rather than the chemical characteristics of the tailings

  2. Efficient simulation of tail probabilities of sums of correlated lognormals

    DEFF Research Database (Denmark)

    Asmussen, Søren; Blanchet, José; Juneja, Sandeep

    We consider the problem of efficient estimation of tail probabilities of sums of correlated lognormals via simulation. This problem is motivated by the tail analysis of portfolios of assets driven by correlated Black-Scholes models. We propose two estimators that can be rigorously shown to be eff......We consider the problem of efficient estimation of tail probabilities of sums of correlated lognormals via simulation. This problem is motivated by the tail analysis of portfolios of assets driven by correlated Black-Scholes models. We propose two estimators that can be rigorously shown...... optimize the scaling parameter of the covariance. The second estimator decomposes the probability of interest in two contributions and takes advantage of the fact that large deviations for a sum of correlated lognormals are (asymptotically) caused by the largest increment. Importance sampling...

  3. Practical considerations of pyrite oxidation control in uranium tailings

    International Nuclear Information System (INIS)

    1984-05-01

    The problems posed by the oxidation of pyrite in uranium tailings include the generation of sulfuric acid and acid sulfate metal salts. These have substantial negative impacts on watercourse biota by themselves, and the lowered pH levels tend to mobilize heavy metals present in the tailings the rate of oxidation of pyrite at lower pH levels is catalyzed by sulfur and iron oxidizing bacteria present in soils. No single clear solution to the problems came from this study. Exclusion of air is a most important preventative of bacterial catalysis of oxidation. Bactericides, chemically breaking the chain of integrated oxidation reactions, maintaining anaerobic conditions, or maintaining a neutral or alkaline pH all reduce the oxidation rate. Removal of pyrite by flotation will reduce but not eliminate the impact of pyrite oxidation. Controlled oxidation of the remaining sulfide in the flotation tails would provide an innocuous tailing so far as acidity generation is concerned

  4. Helium discovered in the tail of an exoplanet

    Science.gov (United States)

    Deming, Drake

    2018-05-01

    As the exoplanet WASP-107b orbits its host star, its atmosphere escapes to form a comet-like tail. Helium atoms detected in the escaping gases give astronomers a powerful tool for investigating exoplanetary atmospheres.

  5. Western Red-tailed Skink Distribution in Southern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Hall, D. B. and Gergor, P. D.

    2011-11-01

    This slide show reports a study to: determine Western Red-tailed Skink (WRTS) distribution on Nevada National Security Site (NNSS); identify habitat where WRTS occur; learn more about WRTS natural history; and document distribution of other species.

  6. Protection coverage parameters indentification for uranium tailing dumps

    International Nuclear Information System (INIS)

    Khakimov, N.; Nazarov, Kh.M.; Mirsaidov, I.U.; Akhmedov, M.Z.

    2012-01-01

    This article is devoted to protection coverage parameters indentification for uranium tailing dumps. Authors noticed that many tailing dumps In Tajikistan do not correspond to modern requirements of territories remediation published by IAEA and current norms of the Republic of Tajikistan. The most dangerous is radionuclide migration i.e., distribution of radioactive substances beyond the uranium tailing dumps territories. One of the basic distribution ways is atmospheric migration. At the same time potentially dangerous factors are: dust rising from open surfaces is the source for contamination distribution to neighboring territories; direct external exposure of public located in close distance to the sites; radioactive gas radon exhalation originating a threat if radionuclides penetration to the human body through breathing passages. Different methods of tailing's negative impact minimization, including coverage with neutral soil layer, coverage with fine-ground worked-out bentonite clay were proposed.

  7. Tailings technology. Decommissioning and rehabilitation remedial action technology development

    International Nuclear Information System (INIS)

    Ramsey, R.W. Jr.

    1982-01-01

    This paper is to provide an overview of technology requirements for long-term uranium mill tailings disposal and remedial actions for existing tailings to ensure their adequate disposal. The paper examines the scientific disciplines that are the basis for the technology of uranium mill tailings stabilization and the design of barriers to control radiological exposure or environmental degradation at the location of tailings disposal. The discussion is presented as a hypothetical course of instruction at a fictitious university. Features of six mechanisms of dispersal or intrusion are examined with brief discussion of the applicable technology development for each. The paper serves as an introduction to subsequent specific technology development papers in the session. (author)

  8. Mixtures of tails in clustered automobile collision claims

    NARCIS (Netherlands)

    R. Kalb (Reinhard); P. Kofman (Paul); A.C.F. Vorst (Ton)

    1996-01-01

    textabstractKnowledge of the tail shape of claim distributions provides important actuarial information. This paper discusses how two techniques commonly used in assessing the most appropriate underlying distribution can be usefully combined. The maximum likelihood approach is theoretically

  9. Modified binders on the basis of flotation tailings

    Science.gov (United States)

    Shapovalov, N. A.; Zagorodnyuk, L. Kh; Shchekina, A. Yu; Gorodov, A. I.

    2018-03-01

    The article proposes compositions of efficient modified composite binders on the basis of portland cement and flotation tailings; the new binders attain the ultimate compressive stress that is twice as high as that of the cement stone. At that, use of annually growing volume of flotation tailings in the production of the composite binder is a rational way for recycling this type of waste and allows saving the planet's natural resources.

  10. Vegetation successfully prevents oxidization of sulfide minerals in mine tailings.

    Science.gov (United States)

    Li, Yang; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

    2016-07-15

    The oxidization of metal sulfide in tailings causes acid mine drainage. However, it remains unclear whether vegetation prevents the oxidization of metal sulfides. The oxidization characteristics and microbial indices of the tailings in the presence of various plant species were investigated to explore the effects of vegetation on the oxidization of sulfide minerals in tailings. The pH, reducing sulfur, free iron oxides (Fed), chemical oxygen consumption (COC) and biological oxygen consumption (BOC) were measured. Key iron- and sulfur-oxidizing bacteria (Acidithiobacillus spp., Leptospirillum spp. and Thiobacillus spp.) were quantified using real-time PCR. The results indicate that vegetation growing on tailings can effectively prevent the oxidization of sulfide minerals in tailings. A higher pH and reducing-sulfur content and lower Fed were observed in the 0-30 cm depth interval in the presence of vegetation compared to bare tailings (BT). The COC gradually decreased with depth in all of the soil profiles; specifically, the COC rapidly decreased in the 10-20 cm interval in the presence of vegetation but gradually decreased in the BT profiles. Imperata cylindrica (IC) and Chrysopogon zizanoides (CZ) profiles contained the highest BOC in the 10-20 cm interval. The abundance of key iron- and sulfur-oxidizing bacteria in the vegetated tailings were significantly lower than in the BT; in particular, IC was associated with the lowest iron- and sulfur-oxidizing bacterial abundance. In conclusion, vegetation successfully prevented the oxidization of sulfide minerals in the tailings, and Imperata cylindrica is the most effective in reducing the number of iron- and sulfur-oxidizing bacteria and helped to prevent the oxidization of sulfide minerals in the long term. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Engineering, environmental and economic planning for tailings disposal

    International Nuclear Information System (INIS)

    Poellot, J.H.

    1982-01-01

    There are two principal points made in this paper. First, mining waste materials, or tailings, are geotechnical materials. Their behavior follows the principles of soil mechanics and is predictable by these principles. Second, proper disposal, meaning safe, environmentally sound and economical disposal, requires planning and recognizing waste disposal as part of the total mining system and process. In the development of these two principles, planning, design, and economic considerations of mine tailings are discussed

  12. Geochemical behavior of uranium mill tailings leachate in the subsurface

    International Nuclear Information System (INIS)

    Brookins, D.G.

    1993-01-01

    Leachate generated from surface disposal of acidic uranium mill tailings at Maybell, CO has impacted groundwater quality within the underlying mineralized Browns Park Formation. The extent of groundwater contamination, however, is located directly beneath the tailings impoundment. The milling process consisted of sulfuric acid extraction of uranium from the feed ore by a complex chemical leaching and precipitation process. Tailings leachate at the site contains elevated concentrations of Al, As, Cd, Mo, Ni, NO 3 , Se, U, and other solutes. From column leach tests, the concentrations of contaminants within tailings pore fluid are SO 4 >NH 4 >NO 3 >U>Se>Ni>As>Cd at pH 4.0. The carbonate buffering capacity of the tailings subsoil has decreased because of calcite dissolution in the presence of acidic leachate. Groundwater quality data, mineralogical and microbiological studies, and geochemical modeling suggest that As, NO 3 , Se, U and other solutes are being removed from solution through precipitation, adsorption, and denitrification processes under reducing conditions. Presence of hydrogen sulfide, liquid and gaseous hydrocarbons, dissolved organic, and abundant pyrite within the Browns Park Formations have maintained reducing conditions subjacent to the tailings impoundment. Groundwater is in close equilibrium with coffinite and uraninite, the primary U(IV) minerals extracted from the Browns Parks Formation. Denitrifying bacteria identified in this study catalyze redox reactions involving NO 3 . Subsequently, contaminant distributions of NO 3 decrease 1000 times beneath the tailings impoundment. Applying geochemical and biochemical processes occurring at Maybell provides an excellent model for in situ aquifer restoration programs considered at other uranium tailings and heavy-metal-mixed waste contaminated sites. (author) 4 figs., 4 tabs., 27 refs

  13. Analysis of radon protection cover on uranium tailings pile

    International Nuclear Information System (INIS)

    Zhang Zhe

    1993-01-01

    The average radon emanation rate of the whole surface over one year was used for evaluating the radon release of uranium tailings pile. The effective of radon protection cover depends on the shape and property of the tailings pile, the properties of covering and the control of air vadose in the pile. It was indicated that the covering with low diffusion coefficient, small porosity and bad permeability was suitable to cover the pile. The analytical formula of the covering layer thickness was given

  14. Double streams of protons in the distant geomagnetic tail

    Science.gov (United States)

    Villante, U.; Lazarus, A. J.

    1975-01-01

    Two intermingled streams of protons have been observed in the distant geomagnetic tail. The number densities of the two streams are comparable, and their velocity difference tends to lie along the field direction. The lower-velocity stream is probably composed of magnetosheath protons which have diffused through the boundary of the distant tail. The higher-velocity stream appears to originate in the field reversal region.

  15. Environmental Risk Assessment System for Phosphogypsum Tailing Dams

    OpenAIRE

    Xin Sun; Ping Ning; Xiaolong Tang; Honghong Yi; Kai Li; Lianbi Zhou; Xianmang Xu

    2013-01-01

    This paper may be of particular interest to the readers as it provides a new environmental risk assessment system for phosphogypsum tailing dams. In this paper, we studied the phosphogypsum tailing dams which include characteristics of the pollution source, environmental risk characteristics and evaluation requirements to identify the applicable environmental risk assessment methods. Two analytical methods, that is, the analytic hierarchy process (AHP) and fuzzy logic, were used to handle the...

  16. Lung cancer risks in the vicinity of uranium tailings sites

    International Nuclear Information System (INIS)

    Rogers, V.C.; Sandquist, G.M.

    1982-04-01

    Lung cancer mortality data have been assembled for many counties of interest to the Uranium Mill Tailings Remedial Action Program (UMTRAP). The counties generally either contain UMTRAP tailings sites or are adjacent to them. The lung cancer rates of nearly all counties are less than the US average rate. In addition, some of the many factors associated with lung cancer are identified as are cancer risk estimators for radon daughters. 17 refs., 19 figs., 1 tab

  17. Double streams of protons in the distant geomagnetic tail

    International Nuclear Information System (INIS)

    Villante, U.; Lazarus, A.J.

    1975-01-01

    Two intermingled streams of protons have been observed in the distant geomagnetic tail. The number densities of the two streams are comparable, and their velocity difference tends to lie along the field direction. The lower-velocity stream is probably composed of magnetosheath protons which have diffused through the boundary of the distant tail. The higher-velocity stream appears to originate in the field reversal region

  18. Preparation of polymeric aluminium ferric chloride from bauxite tailings

    Directory of Open Access Journals (Sweden)

    Ma D.

    2013-01-01

    Full Text Available Bauxite tailings are the main solid wastes in the ore dressing process. The Al2O3 and Fe2O3 contents in bauxite tailings can reach 50% and 13% respectively. The present study proposed a feasible method to use bauxite tailings to prepare polymeric aluminium ferric chloride (PAFC, a new composite inorganic polymer for water purification. Bauxite tailings roasted reacting with hydrochloric acid under air, pickle liquor which mainly contains Fe3+, Al3+ was generated, then calcium aluminate was used to adjust pH value and the basicity of the pickle liquor, the PAFC was subsequently prepared after the polymerization process. The optimal synthesizing parameters for the preparation of PAFC obtained were as follows: the concentration of hydrochloric acid of 24 wt%, ratio of hydrochloric acid to bauxite tailings of 6:1, temperature of 90ºC, leaching time of 2.5 hours, ration of pickle liquor to calcium aluminate of 12:1, polymerization temperature of 90ºC and polymerization time of about 3 hours. The basicity of PAFC was higher than 68%, the sum concentration of Al2O3 and Fe2O3 was beyond 12.5%. The results of flocculation tests indicate that the PAFC has a better performance of removing the turbidity of wastewater compared to PAC, and PAFC prepared by bauxite tailings is a kind of high quality flocculants.

  19. Current practices and options for confinement of uranium mill tailings

    International Nuclear Information System (INIS)

    1981-01-01

    At the United Nations Conference on the Human Environment, which took place in Stockholm from 4 to 6 June 1972, national governments were asked to explore, with the International Atomic Energy Agency and other appropriate international organizations, international co-operation on radioactive waste matters including those of mining and tailings disposal. Since that time the IAEA has been active in the field of uranium and thorium mill tailings management. As part of this activity, the present report describes current practices and options for confinement of uranium mill tailings. It is addressed to technical and administrative personnel who are involved in planning and implementing national and industrial programmes on the management of such tailings. In 1974 and 1975 the IAEA convened meetings of experts to review matters of interest and importance in the management of uranium and thorium mine and mill tailings. These activities led to the publication in 1976 of Management of Wastes from the Mining and Milling of Uranium and Thorium Ores, a Code of Practice and Guide to the Code, IAEA Safety Series No. 44. As a continuation of this activity, the IAEA is here dealing more specifically with the design and siting considerations for the management of uranium mill tailings

  20. Leachability of radioactive constituents from uranium mine tailings

    International Nuclear Information System (INIS)

    Bryant, D.N.; Cohen, D.B.; Durham, R.W.

    1979-04-01

    A project was carried out using lysimeters to determine the leaching of radioactive constituents and BaRaSO 4 from abandoned uranium mine tailings. Lime addition to the surface of acidic abandoned tailings did not reduce the level of radioactive constituents in the leachate. Considerable increases in levels of the radionuclides 230 Th, 232 Th and 22 /8Th, as well as gross alpha and beta activity in the leachate, occurred five months after recycling of BaRaSO 4 sediments to the surface layers of abandoned tailings. After nine months of leaching, the levels of 226 Ra in the leachate were 30% greater than the tailings plus sediment treatment than from tailings only (control). Another experiment compared the quality of effluent flowing over chemically-fixed (solidified) BaRaSO 4 sediments with that of non-fixed (control) in simulated sedimentation ponds. During seven months the release of 226 Ra to water from chemically-fixed BaRaSO 4 sediments remained 3 for phosphorus removal) was applied to supply 3 percent organic matter in the top 15 cm of the revegetated lysimeters. Undiluted effluent and leachate from chemically-fixed BaRaSO 4 sediments and fresh tailings were 100 percent lethal to Daphnia pulex and rainbow trout (Salmo gairdneri) in static 96-hour bioassay tests. Diluted (50 percent) effluent samples were non-toxic. (auth)

  1. Measurement and calculation of radon releases from uranium mill tailings

    International Nuclear Information System (INIS)

    1992-01-01

    The mining and milling of uranium ores produces large quantities of radioactive wastes. Although relatively small in magnitude compared to tailings from metal mining and extraction processes, the present worldwide production of such tailings exceeds 20 million tonnes annually. There is thus a need to ensure that the environmental and health risks from these materials are reduced to an acceptable level. This report has been written as a complement to another publication entitled Current Practices for the Management and Confinement of Uranium Mill Tailings, IAEA Technical Reports Series No. 335, which provides a general overview of all the important factors in the siting, design and construction of tailings impoundments, and in the overall management of tailings with due consideration give to questions of the release of pollutants from tailings piles. The present report provides a comprehensive overview of the release, control and monitoring of radon, including computational methods. The report was first drafted in 1989 and was then reviewed at an Advisory Group meeting in 1990. 42 refs, 9 figs, 3 tabs

  2. Long-term stabilization of uranium mill tailings

    International Nuclear Information System (INIS)

    Voorhees, L.D.; Sale, M.J.; Webb, J.W.; Mulholland, P.J.

    1983-01-01

    The primary hazard associated with uranium mill tailings is exposure to a radioactive gas, radon-222, the concentration of which has been correlated with the occurrence of lung cancer. Previous studies on radon attenuation conclude that the placement of earthen cover materials over the tailings is the most effective technique for reducing radioactive emissions and dispersal of tailings. The success of such a plan, however, is dependent on ensuring the long-term integrity of these cover materials. Soil erosion from water and wind is the major natural cause of destabilizing earthen cover materials. Field data related to the control of soil loss are limited and only indirectly apply to the problem of isolation of uranium mill tailings over very long time periods (up to 80,000 a). However, sufficient information is available to determine benefits that will result from the changes in specific design variables and to evaluate the need for different design strategies among potential disposal sites. The three major options available for stabilization of uranium mill tailings are: rock cover, soil and revegetation, or a combination of both on different portions of the tailings cover. The optimal choice among these alternatives depends on site-specific characteristics such as climate and local geomorphology and soils, and on design variables such as embankment, heights and slopes, modification of upstream drainage, and revegetation practices. Generally, geomorphic evidence suggests that use of soil and vegetation alone will not be adequate to reduce erosion on slopes greater than about 5 to 9%

  3. Geochemical Characterization of Copper Tailings after Legume Revegetation

    Directory of Open Access Journals (Sweden)

    Justine Perry T. Domingo

    2014-12-01

    Full Text Available Knowledge on the geochemistry of mine tailings is important in understanding the challenges in establishing vegetation cover on tailings dumps and mined out areas. In this study, the mineralogy and trace element composition of copper tailings were examined. Two legume species, Calopogonium mucunoides and Centrosema molle, were utilized to investigate the possible effects of these plants in the geochemical development of mine tailings into soil-like material. The initial mineralogical and chemical analysis of the tailings samples indicated poor conditions for plant growth—minimal levels of major nutrients and organic matter as well as elevated copper concentrations. Despite these conditions, the two legume species exhibited good growth rates. Both legumes have likewise signif icantly reduced heavy metal concentrations in the tailings, indicating the possibility of metal hyperaccumulation in the plant tissue. The mineral composition has been retained even after revegetation; nevertheless, breakdown of primary minerals and subsequent formation of clay minerals were detected. These results provide insights on the transformation of toxic materials into habitable substrates for sustained plant growth.

  4. Bacterial reduction of selenium in coal mine tailings pond sediment

    Energy Technology Data Exchange (ETDEWEB)

    Siddique, T.; Arocena, J.M.; Thring, R.W.; Zhang, Y.Q. [University of North British Columbia, Prince George, BC (Canada)

    2007-05-15

    Sediment from a storage facility for coal tailings solids was assessed for its capacity to reduce selenium (Se) by native bacterial community. One Se{sup 6+}-reducing bacterium Enterobacter hormaechei (Tar11) and four Se{sup 4+}-reducing bacteria, Klebsiella pneumoniae (Tar1), Pseudomonasfluorescens (Tar3), Stenotrophomonas maltophilia (Tar6), and Enterobacter amnigenus (Tar8) were isolated from the sediment. Enterobacter horinaechei removed 96% of the added Se{sup 6+} (0.92 mg L{sup -1} from the effluents when Se6+ was determined after 5 d of incubation. Analysis of the red precipitates showed that Se{sup 6+} reduction resulted in the formation of spherical particles ({lt}1.0 {mu} m) of Se 0 as observed under scanning electron microscope (SEM) and confirmed by EDAX. Selenium speciation was performed to examine the fate of the added Se{sup 6+} in the sediment with or without addition of Enterobacter hormaechei cells. More than 99% of the added Se{sup 6+} (about 2.5 mg L{sup -1}) was transformed in the nonsterilized sediment (without Enterobacter hormaechei cells) as well as in the sterilized (heat-killed) sediment (with Enterobacter hormaechei cells). The results of this study suggest that the lagoon sediments at the mine site harbor Se{sup 6+}- and Se{sup 4+} -reducing bacteria and may be important sinks for soluble Se (Se{sup 6+} and Se{sup 4+}). Enterobacter hormaechei isolated from metal-contaminated sediment may have potential application in removing Se from industrial effluents.

  5. Crab Cavity effects on transverse distribution evolution and tail cleaning in the HL-LHC

    CERN Document Server

    Baudrenghien, Philippe; Steeper, S; Tucker, D; Wieker, Devin; CERN. Geneva. ATS Department

    2018-01-01

    This work presents the transverse action and tune distribution evolution as a function of the Crab Cavity RF noise Power Spectral Density (PSD). In addition, it presents the potential for transverse tail cleaning through the deliberate injection of noise with an appropriate PSD. Such a procedure would be very beneficial since it would strongly reduce the transverse losses following a crab cavity trip, and could complement or substitute the electron lens approach.

  6. Evaluation of inactive uranium mill tailings sites for liner requirements: Characterization and interaction of tailings, soil, and liner materials

    International Nuclear Information System (INIS)

    Relyea, J.F.; Martin, W.J.

    1982-01-01

    This paper summarizes the results of laboratory experiments using soils from Clive, Utah and tailings samples from three inactive uranium processing sites. The results are to be used to predict contaminant behavior for comparison with the regulatory criteria to decide whether a liner is needed. The interactions of leachates with soils and liner material were studied using both batch and column methods. It is determined that batch leaching tests are suitable for screening a large number of tailings samples for relative contaminant concentrations between samples but not for determining contaminant concentrations and release rates in tailings leachate. The results of column leaching tests on samples of tailings from inactive sites indicate that contaminant concentrations are highest in initial leachate from the columns and that concentrations decrease by an order of magnitude or more after one pore volume

  7. E-Tailing on Zazzle.Com

    Science.gov (United States)

    Ashley, Christy

    2013-01-01

    An innovative project was designed for a retail management course to enhance critical thinking skills and provide hands-on learning about marketing strategy in an electronic retail context. Students created, promoted, and managed online stores using Zazzle.com, which retails user-generated designs, and analyzed the results of their efforts.…

  8. Suspended electrodialytic extraction of toxic elements for detoxification of three different mine tailings

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Ottosen, Lisbeth M.; Hansen, H.K.

    2016-01-01

    have shown that electrokinetic treatment can remove Cd, Cu, Pb, and Zn from tailings soils; As from tailings; and Cu from tailings. Still, however, a major concern is the long treatment-time required for the element-transport through the tailings matrix. Therefore several enhancement methods have been...

  9. The radiological impacts of uranium mill tailings - a review with special emphasis on the tailings at Ranstad in Sweden

    International Nuclear Information System (INIS)

    Snihs, J.O.; Agnedal, P.O.

    1978-07-01

    The environmental impact of uranium mill tailings can be expressed in collective dose commitment and corresponding detriment per MWsub(e).Y energy produced by the uranium which corresponds to the amount of waste of interest. The methods of dose commitment calculations are discussed and it is suggested for the purpose of estimation of the detriment to limit the commitment to 10,000 years. The external radiation from the tailings is easily reduced by covering but in case of a future settlement on the tailings the collective dose commitment will be some hundreds to thousands of manrad/MWsub(e).Y depending on the quality of the uranium ore. The dispersion of dust from uncovered tailings is mainly a local problem and the collective dose commitment for critical tissues in the lung will be less than a manrad/MWsub(e).Y. In the long run the cover may be lost and the resultant collective dose commitment for the critical tissues in the lung will be a few tens of manrad/MWsub(e).Y depending on the quality of the tailings. The effects of global dispersion of the material in the tailings are also discussed

  10. Global morphological analysis of marine viruses shows minimal regional variation and dominance of non-tailed viruses.

    Science.gov (United States)

    Brum, Jennifer R; Schenck, Ryan O; Sullivan, Matthew B

    2013-09-01

    Viruses influence oceanic ecosystems by causing mortality of microorganisms, altering nutrient and organic matter flux via lysis and auxiliary metabolic gene expression and changing the trajectory of microbial evolution through horizontal gene transfer. Limited host range and differing genetic potential of individual virus types mean that investigations into the types of viruses that exist in the ocean and their spatial distribution throughout the world's oceans are critical to understanding the global impacts of marine viruses. Here we evaluate viral morphological characteristics (morphotype, capsid diameter and tail length) using a quantitative transmission electron microscopy (qTEM) method across six of the world's oceans and seas sampled through the Tara Oceans Expedition. Extensive experimental validation of the qTEM method shows that neither sample preservation nor preparation significantly alters natural viral morphological characteristics. The global sampling analysis demonstrated that morphological characteristics did not vary consistently with depth (surface versus deep chlorophyll maximum waters) or oceanic region. Instead, temperature, salinity and oxygen concentration, but not chlorophyll a concentration, were more explanatory in evaluating differences in viral assemblage morphological characteristics. Surprisingly, given that the majority of cultivated bacterial viruses are tailed, non-tailed viruses appear to numerically dominate the upper oceans as they comprised 51-92% of the viral particles observed. Together, these results document global marine viral morphological characteristics, show that their minimal variability is more explained by environmental conditions than geography and suggest that non-tailed viruses might represent the most ecologically important targets for future research.

  11. Analysis of the histone protein tail and DNA in nucleosome using molecular dynamics simulation

    Science.gov (United States)

    Fujimori, R.; Komatsu, Y.; Fukuda, M.; Miyakawa, T.; Morikawa, R.; Takasu, M.

    2013-02-01

    We study the effect of the tails of H3 and H4 histones in the nucleosomes, where DNA and histones are packed in the form of chromatin. We perform molecular dynamics simulations of the complex of DNA and histones and calculate the mean square displacement and the gyration radius of the complex of DNA and histones for the cases with tails intact and the cases with tails missing. Our results show that the H3 tails are important for the motion of the histones. We also find that the motion of one tail is affected by other tails, although the tails are distanced apart, suggesting the correlated motion in biological systems.

  12. Thermal electron heating rate: a derivation

    International Nuclear Information System (INIS)

    Hoegy, W.R.

    1983-11-01

    The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons, (2) a heating term evaluated on the energy surface m(e)/2 E(T) at the transition between Maxwellian and tail electrons at E(T), and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two

  13. Evaluation of pyritic mine tailings as a plant growth substrate.

    Science.gov (United States)

    Roseby, Stuart J; Kopittke, Peter M; Mulligan, David R; Menzies, Neal W

    2017-10-01

    At the Kidston gold mine, Australia, the direct establishment of vegetation on tailings was considered as an alternative to the use of a waste rock cover. The tailings acid/base account was used to predict plant growth limitation by acidity, and thus methods capable of identifying tailings that would acidify to pH 4.5 or lower were sought. Total S was found to be poorly correlated with acid-generating sulfide, and total C was poorly correlated with acid-neutralizing carbonate, precluding the use of readily determined total S and C as predictors of net acid generation. Therefore, the selected approach used assessment of sulfide content as a predictor of acid generation, and carbonate content as a measure of the acid-neutralizing capacity available at pH 5 and above. Using this approach, the majority of tailings (67%) were found to be non-acid generating. However, areas of potentially acid-generating tailings were randomly distributed across the dam, and could only be located by intensive sampling. The limitations imposed by the large sample numbers, and costly analysis of sulfide and carbonate, make it impractical to identify and ameliorate acid-generating areas prior to vegetation establishment. However, as only a small proportion of the tailings will acidify, a strategy of re-treating acid areas following oxidation is suggested. The findings of the present study will assist in the selection of appropriate methods for the prediction of net acid generation, particularly where more conservative measurements are required to allow vegetation to be established directly in tailings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings?

    Science.gov (United States)

    Huang, Longbin; Baumgartl, Thomas; Mulligan, David

    2012-01-01

    Background Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil – mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model. Scope Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings' properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed. Conclusions When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to

  15. Tail Docking and Ear Cropping Dogs: Public Awareness and Perceptions.

    Directory of Open Access Journals (Sweden)

    Katelyn E Mills

    Full Text Available Tail docking and ear cropping are two surgical procedures commonly performed on many dog breeds. These procedures are classified as medically unnecessary surgeries whose purpose is primarily cosmetic. Available attitude research surrounding these controversial practices has been limited to surveys of veterinarians and dog breeders familiar with both practices. The aim of this project was to: 1 assess public awareness of tail docking and ear cropping, 2 determine whether physical alteration of a dog affects how the dog, and 3 owner are perceived. In Experiment 1 awareness was measured using a combination of both explicit and implicit measures. We found that 42% of participants (n = 810 were unable to correctly explain the reason why tail docked and ear cropped dogs had short ears and tails. Similarly, an implicit measure of awareness ('nature vs nurture task', found that the majority of participants believed short tails and erect ears were a consequence of genetics rather than something the owner or breeder had done. The results obtained in Experiment 2 (n = 392 provide evidence that ear cropped and tail docked dogs are perceived differently than an identical dog in its 'natural' state. Modified dogs were perceived as being more aggressive, more dominant, less playful and less attractive than natural dogs. Experiment 3 (n = 410 is the first evidence that owners of modified dogs are perceived as being more aggressive, more narcissistic, less playful, less talkative and less warm compared to owners of natural dogs. Taken together, these results suggest that although a significant proportion of subjects appear unaware of the practices of tail docking and ear cropping in dogs, these procedures have significant impacts on how modified dogs and their owners are perceived by others.

  16. Tail Docking and Ear Cropping Dogs: Public Awareness and Perceptions.

    Science.gov (United States)

    Mills, Katelyn E; Robbins, Jesse; von Keyserlingk, Marina A G

    2016-01-01

    Tail docking and ear cropping are two surgical procedures commonly performed on many dog breeds. These procedures are classified as medically unnecessary surgeries whose purpose is primarily cosmetic. Available attitude research surrounding these controversial practices has been limited to surveys of veterinarians and dog breeders familiar with both practices. The aim of this project was to: 1) assess public awareness of tail docking and ear cropping, 2) determine whether physical alteration of a dog affects how the dog, and 3) owner are perceived. In Experiment 1 awareness was measured using a combination of both explicit and implicit measures. We found that 42% of participants (n = 810) were unable to correctly explain the reason why tail docked and ear cropped dogs had short ears and tails. Similarly, an implicit measure of awareness ('nature vs nurture task'), found that the majority of participants believed short tails and erect ears were a consequence of genetics rather than something the owner or breeder had done. The results obtained in Experiment 2 (n = 392) provide evidence that ear cropped and tail docked dogs are perceived differently than an identical dog in its 'natural' state. Modified dogs were perceived as being more aggressive, more dominant, less playful and less attractive than natural dogs. Experiment 3 (n = 410) is the first evidence that owners of modified dogs are perceived as being more aggressive, more narcissistic, less playful, less talkative and less warm compared to owners of natural dogs. Taken together, these results suggest that although a significant proportion of subjects appear unaware of the practices of tail docking and ear cropping in dogs, these procedures have significant impacts on how modified dogs and their owners are perceived by others.

  17. Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings?

    Science.gov (United States)

    Huang, Longbin; Baumgartl, Thomas; Mulligan, David

    2012-07-01

    Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil - mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model. Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings' properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed. When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to develop hydro-geochemically stable

  18. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  19. The mechanism of DNA ejection in the Bacillus anthracis spore-binding phage 8a revealed by cryo-electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xiaofeng [Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030 (United States); Walter, Michael H. [Department of Biology, University of Northern Iowa, Cedar Falls, IA 50614 (United States); Paredes, Angel [Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030 (United States); Morais, Marc C., E-mail: mcmorais@utmb.edu [Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555 (United States); Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States); Liu, Jun, E-mail: Jun.Liu.1@uth.tmc.edu [Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030 (United States)

    2011-12-20

    The structure of the Bacillus anthracis spore-binding phage 8a was determined by cryo-electron tomography. The phage capsid forms a T = 16 icosahedron attached to a contractile tail via a head-tail connector protein. The tail consists of a six-start helical sheath surrounding a central tail tube, and a structurally novel baseplate at the distal end of the tail that recognizes and attaches to host cells. The parameters of the icosahedral capsid lattice and the helical tail sheath suggest protein folds for the capsid and tail-sheath proteins, respectively, and indicate evolutionary relationships to other dsDNA viruses. Analysis of 2518 intact phage particles show four distinct conformations that likely correspond to four sequential states of the DNA ejection process during infection. Comparison of the four observed conformations suggests a mechanism for DNA ejection, including the molecular basis underlying coordination of tail sheath contraction and genome release from the capsid.

  20. Critical ionization velocity as a mechanism for producing Titan's plasma tail

    International Nuclear Information System (INIS)

    Galeev, A.A.; Khabibrakhmanov, I.KH.

    1984-01-01

    The phenomenon of a critical ionization velocity may explain the anomalous interaction between the magnetospheric plasma corotating with Saturn and the atmosphere of Titan. Although the dominant role will be played by the lower-hybrid instability due to the counterstreaming of the magnetospehric plasma and newly formed atmospheric ions, charge-separation effects caused by the very large Larmor radius of the new nitrogen ions also may trigger instability. The kinetic energy of the newly formed ions will be conveyed to the electrons by plasma waves generated in the counterflow, thereby exciting the atmospheric atoms to emit radiation. The limiting plasma density and electron temperature in Titan's plasma tail and the frequency spectrum of the waves that develop are determined and compared against the Voyager measurements. 11 references

  1. Long-Term Performance of Uranium Tailings Disposal Cells - 13340

    International Nuclear Information System (INIS)

    Bostick, Kent; Daniel, Anamary; Pill, Ken; Tachiev, Georgio; Noosai, Nantaporn; Villamizar, Viviana

    2013-01-01

    Recently, there has been interest in the performance and evolution of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cell covers because some sites are not compliant with groundwater standards. Field observations of UMTRA disposal cells indicate that rock covers tend to become vegetated and that saturated conductivities in the upper portion of radon barriers may increase due to freeze/thaw cycles and biointrusion. This paper describes the results of modeling that addresses whether these potential changes and transient drainage of moisture in the tailings affect overall performance of the disposal cells. A numerical unsaturated/saturated 3-dimensional flow model was used to simulate whether increases in saturated conductivities in radon barriers with rock covers affect the overall performance of the disposal cells using field data from the Shiprock, NM, UMTRA site. A unique modeling approach allowed simulation with daily climatic conditions to determine changes in moisture and moisture flux from the disposal cell. Modeling results indicated that increases in the saturated conductivity at the top of radon barrier do not influence flux from the tailings with time because the tailings behave similar hydraulically to the radon barrier. The presence of a thin layer of low conductivity material anywhere in the cover or tailings restricts flux in the worst case to the saturated conductivity of that material. Where materials are unsaturated at depth within the radon barrier of tailings slimes, conductivities are typically less than 10 -8 centimeters per second. If the low conductivity layer is deep within the disposal cell, its saturated properties are less likely to change with time. The significance of this modeling is that operation and maintenance of the disposal cells can be minimized if they are allowed to progress to a natural condition with some vegetation and soil genesis. Because the covers and underlying tailings have a very low saturated

  2. Long-Term Performance of Uranium Tailings Disposal Cells - 13340

    Energy Technology Data Exchange (ETDEWEB)

    Bostick, Kent; Daniel, Anamary; Pill, Ken [Professional Project Services, Inc., 1100 Bethel Valley Road, Oak Ridge, TN, 37922 (United States); Tachiev, Georgio; Noosai, Nantaporn; Villamizar, Viviana [Florida International University, 10555 W. Flagler St., EC 2100, Miami FL, 33174 (United States)

    2013-07-01

    Recently, there has been interest in the performance and evolution of Uranium Mill Tailings Remedial Action (UMTRA) Project disposal cell covers because some sites are not compliant with groundwater standards. Field observations of UMTRA disposal cells indicate that rock covers tend to become vegetated and that saturated conductivities in the upper portion of radon barriers may increase due to freeze/thaw cycles and biointrusion. This paper describes the results of modeling that addresses whether these potential changes and transient drainage of moisture in the tailings affect overall performance of the disposal cells. A numerical unsaturated/saturated 3-dimensional flow model was used to simulate whether increases in saturated conductivities in radon barriers with rock covers affect the overall performance of the disposal cells using field data from the Shiprock, NM, UMTRA site. A unique modeling approach allowed simulation with daily climatic conditions to determine changes in moisture and moisture flux from the disposal cell. Modeling results indicated that increases in the saturated conductivity at the top of radon barrier do not influence flux from the tailings with time because the tailings behave similar hydraulically to the radon barrier. The presence of a thin layer of low conductivity material anywhere in the cover or tailings restricts flux in the worst case to the saturated conductivity of that material. Where materials are unsaturated at depth within the radon barrier of tailings slimes, conductivities are typically less than 10{sup -8} centimeters per second. If the low conductivity layer is deep within the disposal cell, its saturated properties are less likely to change with time. The significance of this modeling is that operation and maintenance of the disposal cells can be minimized if they are allowed to progress to a natural condition with some vegetation and soil genesis. Because the covers and underlying tailings have a very low saturated

  3. Reactivity of the isolated perfused rat tail vascular bed

    Directory of Open Access Journals (Sweden)

    A.S. França

    1997-07-01

    Full Text Available Isolated segments of the perfused rat tail artery display a high basal tone when compared to other isolated arteries such as the mesenteric and are suitable for the assay of vasopressor agents. However, the perfusion of this artery in the entire tail has not yet been used for functional studies. The main purpose of the present study was to identify some aspects of the vascular reactivity of the rat tail vascular bed and validate this method to measure vascular reactivity. The tail severed from the body was perfused with Krebs solution containing different Ca2+ concentrations at different flow rates. Rats were anesthetized with sodium pentobarbital (65 mg/kg and heparinized (500 U. The tail artery was dissected near the tail insertion, cannulated and perfused with Krebs solution plus 30 µM EDTA at 36oC and 2.5 ml/min and the procedures were started after equilibration of the perfusion pressure. In the first group a dose-response curve to phenylephrine (PE (0.5, 1, 2 and 5 µg, bolus injection was obtained at different flow rates (1.5, 2.5 and 3.5 ml/min. The mean perfusion pressure increased with flow as well as PE vasopressor responses. In a second group the flow was changed (1.5, 2, 2.5, 3 and 3.5 ml/min at different Ca2+ concentrations (0.62, 1.25, 2.5 and 3.75 mM in the Krebs solution. Increasing Ca2+ concentrations did not alter the flow-pressure relationship. In the third group a similar protocol was performed but the rat tail vascular bed was perfused with Krebs solution containing PE (0.1 µg/ml. There was an enhancement of the effect of PE with increasing external Ca2+ and flow. PE vasopressor responses increased after endothelial damage with air and CHAPS, suggesting an endothelial modulation of the tone of the rat tail vascular bed. These experiments validate the perfusion of the rat tail vascular bed as a method to investigate vascular reactivity

  4. Probing of flowing electron plasmas

    International Nuclear Information System (INIS)

    Himura, H.; Nakashima, C.; Saito, H.; Yoshida, Z.

    2001-01-01

    Probing of streaming electron plasmas with finite temperature is studied. For the first time, a current-voltage characteristic of an electric probe is measured in electron plasmas. Due to the fast flow of the electron plasmas, the characteristic curve spreads out significantly and exhibits a long tail. This feature can be explained calculating the currents collected to the probe. In flowing electron plasmas, the distribution function observed in the laboratory frame is non-Maxwellian even if the plasmas come to a state of thermal equilibrium. Another significant feature of the characteristic is that it determines a floating potential where the current equals zero, despite there being very few ions in the electron plasma. A high impedance probe, which is popularly used to determine the space potential of electron plasmas, outputs the potential. The method is available only for plasmas with density much smaller than the Brillouin limit

  5. A review on in situ phytoremediation of mine tailings.

    Science.gov (United States)

    Wang, Li; Ji, Bin; Hu, Yuehua; Liu, Runqing; Sun, Wei

    2017-10-01

    Mine tailings are detrimental to natural plant growth due to their physicochemical characteristics, such as high pH, high salinity, low water retention capacity, high heavy metal concentrations, and deficiencies in soil organic matter and fertility. Thus, the remediation of mine tailings has become a key issue in environmental science and engineering. Phytoremediation, an in situ cost-effective technology, is emerging as the most promising remediation method for mine tailings by introducing tolerant plant species. It is particularly effective in dealing with large-area mine tailings with shallow contamination of organic, nutrient and metal pollutants. In this review, the background, concepts and applications of phytoremediation are comprehensively discussed. Furthermore, proper amendments used to improve the physical, chemical and biological properties of mine tailings are systematically reviewed and compared. Emphasis is placed on the types and characteristics of tolerant plants and their role in phytoremediation. Moreover, the role of microorganisms and their mechanism in phytoremediation are also discussed in-depth. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Two active galaxies with tidal tails and companions

    International Nuclear Information System (INIS)

    Keel, W.C.

    1985-01-01

    Spectroscopic, imaging, and radio observations of the tidally disturbed active systems VV 144 and I Zw 96 are presented, and indicate that the prominent optical extensions seen in both cases represent tidal tails rather than matter ejected from their nuclei (jets). This conclusion is based on the presence of stellar spectral features in the tails, lack of significant ionized gas over most of their length, and lack of radio emission outside the nuclei. Discrete knots in these tails are identified with remnant cores of the companion galaxies responsible for the morphological disturbances of the main galaxies and perhaps contributing to their nuclear activity. In both cases, the dynamics of the interactions are unusual in nature or viewing geometry. VV 144 is seen in the common plane of interaction and disk rotation, appearing strongly foreshortened. I Zw 96 shows tails associated with two companions; each is accompanied by changes in tail structure. This may be the result of a binary system of spirals colliding with a giant elliptical galaxy. 18 references

  7. Application of tailings flow analyses to field conditions

    International Nuclear Information System (INIS)

    Bryant, S.M.

    1983-01-01

    Catastrophic failures of tailings impoundments, in which liquefied tailings flow over substantial distances, pose severe hazards to the health and safety of people in downstream areas, and have a potential for economic and environmental devastation. The purpose of this study, an extension of prior investigations, was to develop procedures to measure Bingham flow parameters for mine tailings. In addition, the analytical procedures developed by Lucia (1981) and Jeyapalan (1980) for predicting the consequences of tailings flow failures were evaluated and applied to the Tenmile Tailings Pond at Climax, Colorado. Revisions in the simplified equilibrium procedure, developed by Lucia (1981), make it more compatible with infinite slope solutions. Jeyapalan's model was evaluated using a simple rheological analogy, and it appears there are some numerical difficulties with the operation of the computer program TFLOW used to model the displacements and velocities of flow slides. Comparable flow distances can be determined using either model if the flow volume used in the simplified equilibrium procedure is estimated properly. When both analytical procedures were applied to the Tenmile Pond, it was concluded there was no potential for a flow slide at the site

  8. On the statistical properties and tail risk of violent conflicts

    Science.gov (United States)

    Cirillo, Pasquale; Taleb, Nassim Nicholas

    2016-06-01

    We examine statistical pictures of violent conflicts over the last 2000 years, providing techniques for dealing with the unreliability of historical data. We make use of a novel approach to deal with fat-tailed random variables with a remote but nonetheless finite upper bound, by defining a corresponding unbounded dual distribution (given that potential war casualties are bounded by the world population). This approach can also be applied to other fields of science where power laws play a role in modeling, like geology, hydrology, statistical physics and finance. We apply methods from extreme value theory on the dual distribution and derive its tail properties. The dual method allows us to calculate the real tail mean of war casualties, which proves to be considerably larger than the corresponding sample mean for large thresholds, meaning severe underestimation of the tail risks of conflicts from naive observation. We analyze the robustness of our results to errors in historical reports. We study inter-arrival times between tail events and find that no particular trend can be asserted. All the statistical pictures obtained are at variance with the prevailing claims about ;long peace;, namely that violence has been declining over time.

  9. Assessment of water quality around Jaduguda uranium tailings ponds

    International Nuclear Information System (INIS)

    Mohanty, A.K.; Gurunadha Rao, V.V.S.; Ramesh, G.; Surinaidu, L.; Thama Rao, G.; Dhakate, R.; Sarangi, A.K.; Nair, R.N.

    2010-01-01

    The environmental impacts of uranium mining and milling activities are of great concern in many countries for the last three decades. These impacts range from the creation of massive stockpiles of radioactive and toxic waste rock and sand-like tailings to serious contamination of surface and groundwater with radioactive and toxic pollutants, and releases of conventional, toxic and radioactive air pollutants. Uranium mining is also associated with high concentrations of highly toxic heavy metals, which are a major source of surface and groundwater contamination. Depending upon the hydraulic properties of the fractures involved, contaminated ground water may be transported many miles from its point of origin before feeding into an aquifer. Tailings pond may contaminate the groundwater regime by continuous seepage and leaching of radionuclides and other toxic metals due to interaction of rain water through the tailings ponds. The uranium milling and tailings pond operations were started at Jaduguda since 1968. A comprehensive geological and geophysical investigation has been carried out in the Jaduguda watershed covering the tailings ponds to understand the geohydrological characteristics of the region. High resolution electrical resistivity tomography (ERT) surveys have been carried out to delineate the aquifer geometry. Water quality analyses were carried out in three seasons covering from premonsoon to postmonsoon period during 2008-2009. Uranium concentrations have been observed in the dug wells, surface water and monitoring wells

  10. Results of evaluation of tailing dumps dust intensity

    Directory of Open Access Journals (Sweden)

    Masloboev V. A.

    2016-03-01

    Full Text Available A set of most acceptable and well-known methods of dust intensity evaluation has been defined and tested (dependence of Westphal D. L. et al. and DEAD scheme based on the analysis of exiting approaches (deserts, tailing dumps, etc.. The description of the chosen methods has been given. The determination of dynamic velocity u* and velocity at the height of +10 m above the dusting surface u10 which are necessary to evaluate the dust intensity has been demonstrated. The method is based on two-dimensional numerical model of atmosphere aerodynamics in the area of "tailing dumps of ANOF-2 ‒ the town of Apatity". The study provides calculations of horizontal velocity at the height of +10 m above the dusting surface at the wind speed varying from 5 to 23 m/sec. The work also suggests the results of graphical data processing related to tailing grain size distribution from the surface of the firmly established surface of the tailing dumps of ANOF-2. Comparative analysis has been given and the peculiarities of interval (based on grains sizes dust intensity of the tailing dumps of ANOF-2 have been shown using the dependence of Westphal D. L. et al. and DEAD scheme within the wind speed range. The received values of dust intensity at the lower range limit are close to the "maximum specific dust off" value which is used by project specialists for documentation development

  11. Evolution of Acid Mine Drainage Formation in Sulphidic Mine Tailings

    Directory of Open Access Journals (Sweden)

    Bernhard Dold

    2014-07-01

    Full Text Available Sulphidic mine tailings are among the largest mining wastes on Earth and are prone to produce acid mine drainage (AMD. The formation of AMD is a sequence of complex biogeochemical and mineral dissolution processes. It can be classified in three main steps occurring from the operational phase of a tailings impoundment until the final appearance of AMD after operations ceased: (1 During the operational phase of a tailings impoundment the pH-Eh regime is normally alkaline to neutral and reducing (water-saturated. Associated environmental problems include the presence of high sulphate concentrations due to dissolution of gypsum-anhydrite, and/or effluents enriched in elements such as Mo and As, which desorbed from primary ferric hydroxides during the alkaline flotation process. (2 Once mining-related operations of the tailings impoundment has ceased, sulphide oxidation starts, resulting in the formation of an acidic oxidation zone and a ferrous iron-rich plume below the oxidation front, that re-oxidises once it surfaces, producing the first visible sign of AMD, i.e., the precipitation of ferrihydrite and concomitant acidification. (3 Consumption of the (reactive neutralization potential of the gangue minerals and subsequent outflow of acidic, heavy metal-rich leachates from the tailings is the final step in the evolution of an AMD system. The formation of multi-colour efflorescent salts can be a visible sign of this stage.

  12. Liner evaluation for uranium mill tailings. Final report

    International Nuclear Information System (INIS)

    Buelt, J.L.

    1983-09-01

    The Liner Evaluation for Uranium Mill Tailings Program was conducted to evaluate the need for and performance of prospective lining materials for the long-term management of inactive uranium mill tailings piles. On the basis of program results, two materials have been identified: natural foundation soil amended with 10% sodium bentonite; catalytic airblown asphalt membrane. The study showed that, for most situations, calcareous soils typical of Western US sites adequately buffer tailings leachates and prevent groundwater contamination without additional liner materials or amendments. Although mathematical modeling of disposal sites is recommended on a site-specific basis, there appears to be no reason to expect significant infiltration through the cover for most Western sites. The major water source through the tailings would be groundwater movement at sites with shallow groundwater tables. Even so column leaching studies showed that contaminant source terms were reduced to near maximum contaminant levels (MCL's) for drinking water within one or two pore volumes; thus, a limited source term for groundwater contamination exists. At sites where significant groundwater movement or infiltration is expected and the tailings leachates are alkaline, however, the sodium bentonite or asphalt membrane may be necessary

  13. Denitrification in groundwater at uranium mill tailings sites

    International Nuclear Information System (INIS)

    Goering, Timothy J.; Groffman, Armando; Thomson, Bruce

    1992-01-01

    Nitrates are a major contaminant in groundwater at many Uranium Mill Tailings Remedial Action (UMTRA) sites. Microbial denitrification, the transformation of nitrate to nitrogen gas, may be occurring in groundwater at several UMTRA sites. Denitrification is a biologically mediated process whereby facultative anaerobes use nitrate for respiration under anaerobic conditions. Denitrifying bacteria are ubiquitous in soils, sediments, and water. Denitrification requires nitrate, organic carbon, oxygen-limiting conditions, and trace nutrients, especially phosphorus. The lack of organic carbon is the most common limiting factor for denitrification. Denitrification occurs under a limited range of temperature and pH. The uranium milling processes used at UMTRA sites provided a readily available source of carbon and nitrates for denitrifying bacteria. At the Maybell, Colorado, site, the denitrifying organisms Pseudomonas, Flavobacterium and Acinetobacter were identified in core samples of materials from beneath the tailings. In addition, microcosm experiments simulating aquifer conditions beneath the tailings pile showed an average 40 percent decrease in nitrate concentrations over 13 days. At the New Rifle, Colorado, site, aquifer conditions appear favorable for denitrification. Nitrate and organic carbon are readily available in the groundwater, and redox conditions beneath and downgradient of the tailings pile are relatively anoxic. Downgradient from the tailings, total nitrogen is being removed from the groundwater system at a greater rate than the geochemically conservative anion, chloride. This removal may be due to denitrification and adsorption of ammonium onto clay and silt particles. (author)

  14. Tail dependence and information flow: Evidence from international equity markets

    Science.gov (United States)

    Al Rahahleh, Naseem; Bhatti, M. Ishaq; Adeinat, Iman

    2017-05-01

    Bhatti and Nguyen (2012) used the copula approach to measure the tail dependence between a number of international markets. They observed that some country pairs exhibit only left-tail dependence whereas others show only right-tail. However, the flow of information from uni-dimensional (one-tail) to bi-dimensional (two-tails) between various markets was not accounted for. In this study, we address the flow of information of this nature by using the dynamic conditional correlation (DCC-GARCH) model. More specifically, we use various versions of the DCC models to explain the nexus between the information flow of international equity and to explain the stochastic forward vs. backward dynamics of financial markets based on data for a 15-year period comprising 3,782 observations. We observed that the information flow between the US and Hong Kong markets and between the US and Australian markets are bi-directional. We also observed that the DCC model captures a wider co-movement structure and inter-connectedness compared to the symmetric Joe-Clayton copula.

  15. Problems in the separation of radium from uranium ore tailings

    Energy Technology Data Exchange (ETDEWEB)

    Seeley, F.G.

    1976-01-01

    The radium content of a representative sandstone type of uranium ore was found to be distributed uniformly according to particle size before leaching, but in sulfuric acid-leached tailings was found predominantly in the -325 mesh fraction. The radium leaching characteristics from both ore and sulfate-leached tailings were investigated. Several 1 M salt solutions showed poor to moderate RaSO/sub 4/ dissolution from ''slimes solids'' tailings, while 3 M HNO/sub 3/ or HCl solutions dissolved approximately 95% of the radium content of either ore or tailings. Tests are reported in which -325 mesh sand particles were coated with alkaline-earth sulfates by a special technique to simulate slime solids tailings. The dissolution of RaSO/sub 4/ from these coated sands was decreased by the presence of BaSO/sub 4/, but increased by the presence of CaSO/sub 4/. The interrelationships in the dissolution of mixtures of CaSO/sub 5/, SrSO/sub 4/, BaSO/sub 4/, and RaSO/sub 4/ are shown, and a generalized equation for the estimation of the dissolution of a minor component is presented.

  16. Regeneration of neural crest derivatives in the Xenopus tadpole tail

    Directory of Open Access Journals (Sweden)

    Slack Jonathan MW

    2007-05-01

    Full Text Available Abstract Background After amputation of the Xenopus tadpole tail, a functionally competent new tail is regenerated. It contains spinal cord, notochord and muscle, each of which has previously been shown to derive from the corresponding tissue in the stump. The regeneration of the neural crest derivatives has not previously been examined and is described in this paper. Results Labelling of the spinal cord by electroporation, or by orthotopic grafting of transgenic tissue expressing GFP, shows that no cells emigrate from the spinal cord in the course of regeneration. There is very limited regeneration of the spinal ganglia, but new neurons as well as fibre tracts do appear in the regenerated spinal cord and the regenerated tail also contains abundant peripheral innervation. The regenerated tail contains a normal density of melanophores. Cell labelling experiments show that melanophores do not arise from the spinal cord during regeneration, nor from the mesenchymal tissues of the skin, but they do arise by activation and proliferation of pre-existing melanophore precursors. If tails are prepared lacking melanophores, then the regenerates also lack them. Conclusion On regeneration there is no induction of a new neural crest similar to that seen in embryonic development. However there is some regeneration of neural crest derivatives. Abundant melanophores are regenerated from unpigmented precursors, and, although spinal ganglia are not regenerated, sufficient sensory systems are produced to enable essential functions to continue.

  17. Characterization of Emergent Data Networks Among Long-Tail Data

    Science.gov (United States)

    Elag, Mostafa; Kumar, Praveen; Hedstrom, Margaret; Myers, James; Plale, Beth; Marini, Luigi; McDonald, Robert

    2014-05-01

    Data curation underpins data-driven scientific advancements. It manages the information flux across multiple users throughout data life cycle as well as increases data sustainability and reusability. The exponential growth in data production spanning across the Earth Science involving individual and small research groups, which is termed as log-tail data, increases the data-knowledge latency among related domains. It has become clear that an advanced framework-agnostic metadata and ontologies for long-tail data is required to increase their visibility to each other, and provide concise and meaningful descriptions that reveal their connectivity. Despite the advancement that has been achieved by various sophisticated data management models in different Earth Science disciplines, it is not always straightforward to derive relationships among long-tail data. Semantic data clustering algorithms and pre-defined logic rules that are oriented toward prediction of possible data relationships, is one method to address these challenges. Our work advances the connectivity of related long-tail data by introducing the design for an ontology-based knowledge management system. In this work, we present the system architecture, its components, and illustrate how it can be used to scrutinize the connectivity among datasets. To demonstrate the capabilities of this "data network" prototype, we implemented this approach within the Sustainable Environment Actionable Data (SEAD) environment, an open-source semantic content repository that provides a RDF database for long-tail data, and show how emergent relationships among datasets can be identified.

  18. Green remediation of tailings from the mine using inorganic agents

    Directory of Open Access Journals (Sweden)

    Došić Aleksandar D.

    2017-01-01

    Full Text Available Increasing amounts of residues and waste materials coming from industrial activities in different processes have become an increasingly urgent problem for the future. The paper presents the problem of mine tailings generated in mine “Sase” (Republic of Srpska, Bosnia and Herzegovina with high metal content (Pb, Cu and Zn. Dumpsite of this tailing represents potential risk for water bodies in the vicinity of this location. Chosen treatment process was stabilization/solidification (S/S. Inorganic agents used in this study were fly ash and red mud that represent secondary industrial waste generated on locations relatively near the mine. Therefore, their application can be used as an example of a sustainable solution of regional environmental problem. Further investigations are related to the impact of various factors on metals leaching from mine tailings solidified/stabilized material using the above mentioned immobilization agents. The performance of the immobilizing procedures was examined using several leaching tests: ANS 16.1, TCLP, DIN, MWLP. The results indicated that all S/S samples can be considered as non-hazardous waste, as all leached metal concentrations met the set criteria. These results will further enable the modelling of metals behaviour during long-term leaching from treated mine tailing. The data are invaluable in terms of economically and environmentally sound management of mine tailing.

  19. Denitrification in groundwater at uranium mill tailings sites

    Energy Technology Data Exchange (ETDEWEB)

    Goering, Timothy J [Jacobs Engineering Group, Inc., Albuquerque, NM (United States); Groffman, Armando [Roy F. Weston, Inc., Albuquerque, NM (United States); Thomson, Bruce [University of New Mexico, Albuquerque, NM (United States)

    1992-07-01

    Nitrates are a major contaminant in groundwater at many Uranium Mill Tailings Remedial Action (UMTRA) sites. Microbial denitrification, the transformation of nitrate to nitrogen gas, may be occurring in groundwater at several UMTRA sites. Denitrification is a biologically mediated process whereby facultative anaerobes use nitrate for respiration under anaerobic conditions. Denitrifying bacteria are ubiquitous in soils, sediments, and water. Denitrification requires nitrate, organic carbon, oxygen-limiting conditions, and trace nutrients, especially phosphorus. The lack of organic carbon is the most common limiting factor for denitrification. Denitrification occurs under a limited range of temperature and pH. The uranium milling processes used at UMTRA sites provided a readily available source of carbon and nitrates for denitrifying bacteria. At the Maybell, Colorado, site, the denitrifying organisms Pseudomonas, Flavobacterium and Acinetobacter were identified in core samples of materials from beneath the tailings. In addition, microcosm experiments simulating aquifer conditions beneath the tailings pile showed an average 40 percent decrease in nitrate concentrations over 13 days. At the New Rifle, Colorado, site, aquifer conditions appear favorable for denitrification. Nitrate and organic carbon are readily available in the groundwater, and redox conditions beneath and downgradient of the tailings pile are relatively anoxic. Downgradient from the tailings, total nitrogen is being removed from the groundwater system at a greater rate than the geochemically conservative anion, chloride. This removal may be due to denitrification and adsorption of ammonium onto clay and silt particles. (author)

  20. A tale too long for a tail too short? : identification of characteristics in pigs related to tail biting and other oral manipulations directed at conspecifics

    NARCIS (Netherlands)

    Ursinus, W.W.

    2014-01-01

    Ursinus, W.W. (2014). A tale too long for a tail too short? Identification of

    characteristics in pigs related to tail biting and other oral manipulations directed

    at conspecifics. PhD thesis, Wageningen University, The Netherlands.

    Tail biting in pigs, i.e. the chewing on and

  1. Tails of the dynamical structure factor of 1D spinless fermions beyond the Tomonaga-Luttinger approximation

    International Nuclear Information System (INIS)

    Teber, S.

    2005-12-01

    We consider one-dimensional interacting spinless fermions with a non-linear spectrum in a clean quantum wire (non-linear bosonization). We compute diagrammatically the one-dimensional dynamical structure factor, S(ω, q), beyond the Tomonaga-Luttinger approximation focusing on its tails, i.e. vertical bar ω vertical bar >> vq. We provide a re-derivation, through diagrammatics, of the result of Pustilnik, Mishchenko, Glazman, and Andreev. We also extend their results to finite temperatures and long-range interactions. As applications we determine curvature and interaction corrections to the small- momentum, high-frequency conductivity and the electron-electron scattering rate. (author)

  2. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, J.E.; von Goeler, S.; Bernabei, S.; Bitter, M.; Chu, T.K.; Efthimion, P.; Fisch, N.; Hooke, W.; Hosea, J.; Jobes, F.

    1985-03-01

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed.

  3. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    International Nuclear Information System (INIS)

    Stevens, J.E.; von Goeler, S.; Bernabei, S.

    1985-03-01

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed

  4. Does cortical bone thickness in the last sacral vertebra differ among tail types in primates?

    Science.gov (United States)

    Nishimura, Abigail C; Russo, Gabrielle A

    2017-04-01

    The external morphology of the sacrum is demonstrably informative regarding tail type (i.e., tail presence/absence, length, and prehensility) in living and extinct primates. However, little research has focused on the relationship between tail type and internal sacral morphology, a potentially important source of functional information when fossil sacra are incomplete. Here, we determine if cortical bone cross-sectional thickness of the last sacral vertebral body differs among tail types in extant primates and can be used to reconstruct tail types in extinct primates. Cortical bone cross-sectional thickness in the last sacral vertebral body was measured from high-resolution CT scans belonging to 20 extant primate species (N = 72) assigned to tail type categories ("tailless," "nonprehensile short-tailed," "nonprehensile long-tailed," and "prehensile-tailed"). The extant dataset was then used to reconstruct the tail types for four extinct primate species. Tailless primates had significantly thinner cortical bone than tail-bearing primates. Nonprehensile short-tailed primates had significantly thinner cortical bone than nonprehensile long-tailed primates. Cortical bone cross-sectional thickness did not distinguish between prehensile-tailed and nonprehensile long-tailed taxa. Results are strongly influenced by phylogeny. Corroborating previous studies, Epipliopithecus vindobonensis was reconstructed as tailless, Archaeolemur edwardsi as long-tailed, Megaladapis grandidieri as nonprehensile short-tailed, and Palaeopropithecus kelyus as nonprehensile short-tailed or tailless. Results indicate that, in the context of phylogenetic clade, measures of cortical bone cross-sectional thickness can be used to allocate extinct primate species to tail type categories. © 2017 Wiley Periodicals, Inc.

  5. Asphalt emulsion sealing of uranium mill tailings. 1980 annual report

    International Nuclear Information System (INIS)

    Hartley, J.N.; Koehmstedt, P.L; Esterl, D.J.; Freeman, H.D.; Buelt, J.L.; Nelson, D.A.; Elmore, M.R.

    1981-05-01

    Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado, confirmed that an 8-cm admix seal containing 22 wt% asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation

  6. Commingled uranium-tailings study. Volume II. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-06-30

    Public Law 96-540, Section 213, directs the Secretary of Energy to develop a plan for a cooperative program to provide assistance in the stabilization and management of defense-related uranium mill tailings commingled with other tailings. In developing the plan, the Secretary is further directed to: (1) establish the amount and condition of tailings generated under federal contracts; (2) examine appropriate methodologies for establishing the extent of federal assistance; and (3) consult with the owners and operators of each site. This technical report summarizes US Department of Energy (DOE) and contractor activities in pursuit of items (1), (2), and (3) above. Recommendations regarding policy and a cooperative plan for federal assistance are under separate cover as Volume I.

  7. Field experiment on 222Rn flux from reclaimed uranium tailings

    International Nuclear Information System (INIS)

    Hinton, T.G.

    1983-01-01

    Design and construction techniques are described for a 1.6 ha experimental uranium mill tailings reclamation plot. A passive, activated charcoal device was developed and tested for measurements of radon flux. Experiments on radon flux versus overburden depth showed that tailings covered with 1.5 m of revegetated or 0.3 m of bare overburden had exhalation rates comparable to background. Vegetated subplots exhibited a significantly higher (often an order of magnitude) flux than the bare subplots. Results on the variation of flux over time did not reveal any definitive patterns, possibly due to the high variability among replicates. A positive correlation was demonstrated between precipitation and radon flux. This is discussed in detail and possibly explained by the increase in water content of the micropores within the tailings, which increases the emanation coefficient without adversely effecting the diffusion coefficient of the overburden. 30 references, 7 figures, 3 tables

  8. ANALYZING FAT-TAILED DISTRIBUTIONS IN EMERGING CAPITAL MARKETS

    Directory of Open Access Journals (Sweden)

    FELICIA RAMONA BIRĂU

    2013-05-01

    Full Text Available The aim of this article focuses on analyzing the implications of fat-tailed distributions in emerging capital markets. An essential aspect that was highlighted by most empirical research, especially in terms of emerging capital markets, emphasizes the fact that extreme financial events can not be accurately predicted by the normal distribution. Fat-tailed distributions establish a very effective econometric tool in the analysis of rare events which are characterized by extreme values that occur with a relatively high frequency .The importance of exploring this particular issue derives from the fact that it is fundamental for optimal portfolio selection, derivatives valuation, financial hedging and risk management strategies. The implications of fat-tailed distributions for investment process are significant especially in the turbulent context of the global financial crisis.

  9. Radon diffusion in candidate soils for covering uranium mill tailings

    International Nuclear Information System (INIS)

    Silker, W.B.; Kalkwarf, D.R.

    1983-04-01

    Diffusion coefficients were measured for radon in 34 soils that had been identified by mill personnel as candidate covers for their tailings piles in order to reduce radon emission. These coefficients referred to diffusion in the total pore space of the soils. They were measured in the laboratory by a steady-state method using soil columns compacted to greater than 80% of their Proctor maximum packing densities but with moisture contents generally less than would be expected at a tailings site. An empirical equation was used to extrapolate measured coefficients to value expected at soil-moisture contents representative of tailings sites in the western United States. Extrapolated values for silty sands and clayey sands ranged from 0.004 to 0.06 cm 2 /s. Values for inorganic silts and clays ranged from 0.001 to 0.02 cm 2 /s

  10. Jet disruption in wide-angle tailed radio galaxies

    International Nuclear Information System (INIS)

    Burns, J.O.; Norman, M.L.; Clarke, D.A.

    1986-01-01

    The mechanisms responsible for the bending of the jets and tails of wide-angle tailed (WAT) radio galaxies in clusters are investigated theoretically, with a focus on sharp bends and rapid jet disruption. Large (1 Mpc) and small (200 kpc) WATs are differentiated, and it is suggested that the jet-tail transition in large WATs is due to collisions between the jet and cool clouds of the intracluster medium (ICM). The transition in small WATs is attributed to the passage of the jet through a planar Mach disk perpendicular to the jet flow direction. Such a disk is shown in numerical simulations to form when there is a shocklike jump in ambient pressure at the ISM/ICM interface; the origins of such a jump are explored. 14 references

  11. The Anatomy of the Long Tail of Consumer Demand

    Science.gov (United States)

    Broder, Andrei

    The long tail of consumer demand is consistent with two fundamentally different theories. The first, and more popular hypothesis, is that a majority of consumers have similar tastes and only few have any interest in niche content; the second, is that everyone is a bit eccentric, consuming both popular and niche products. By examining extensive data on user preferences for movies, music, web search, and web browsing, we found overwhelming support for the latter theory. Our investigation suggests an additional factor in the success of "infinite-inventory" retailers such as Netflix and Amazon: besides the significant revenue obtained from tail sales, tail availability may boost head sales by offering consumers the convenience of "one-stop shopping" for both their mainstream and niche interests.

  12. Guidelines for cleanup of uranium tailings from inactive mills

    International Nuclear Information System (INIS)

    Goldsmith, W.A.; Haywood, F.F.; Jacobs, D.G.

    1975-01-01

    Recent experiences in Grand Junction, Colorado, have indicated the significance of uranium tailings as sources of nonoccupational exposure and suggest that current methods for perpetual care and isolation of the large areas covered by tailings piles at inactive mill locations may be inadequate for minimizing human exposure. This paper presents the rationale and the procedures used in reviewing the adequacy of proposed criteria for remedial action at these sites. Exposures due to aquatic, terrestrial, airborne, and direct contamination pathways were compared to determine the most important radionuclides in the pile and their pathways to man. It is shown that the most hazardous components of the tailings are 226 Ra and 230 Th. The long half-lives of these radionuclides require the consideration of continuous occupancy of the vacated site at some future time, even if the immediately projected land use does not anticipate maximum exposure

  13. Accelerating transient drainage from UMTRA Project tailings piles

    International Nuclear Information System (INIS)

    1990-09-01

    The period between the completion of construction of the tailings disposal cell and the establishment of equilibrium moisture content and seepage conditions is considered to be the period of transient drainage. Transient drainage may be due to factors such as construction water, precipitation, or residual water from the milling process. Transient seepage rates usually exceed steady state seepage rates. If the transient seepage rate causes contaminant levels to exceed groundwater compliance standards, then an alternative groundwater compliance strategy or technical approach to reduce or mitigate the effects of the drainage must be adopted. This study examines methods to accelerate the transient drainage of soils and hence to remove excess pore water from tailings in UMTRA Project disposal cells. The technical and economic feasibility of possible methods is examined. In order to perform comparative economical analyses of the various methods, an example tailings pile is postulated. This pile is considered to be 300 meters by 300 meters by 10 meters in thickness

  14. Correlation between length and tilt of lipid tails

    Science.gov (United States)

    Kopelevich, Dmitry I.; Nagle, John F.

    2015-10-01

    It is becoming recognized from simulations, and to a lesser extent from experiment, that the classical Helfrich-Canham membrane continuum mechanics model can be fruitfully enriched by the inclusion of molecular tilt, even in the fluid, chain disordered, biologically relevant phase of lipid bilayers. Enriched continuum theories then add a tilt modulus κθ to accompany the well recognized bending modulus κ. Different enrichment theories largely agree for many properties, but it has been noticed that there is considerable disagreement in one prediction; one theory postulates that the average length of the hydrocarbon chain tails increases strongly with increasing tilt and another predicts no increase. Our analysis of an all-atom simulation favors the latter theory, but it also shows that the overall tail length decreases slightly with increasing tilt. We show that this deviation from continuum theory can be reconciled by consideration of the average shape of the tails, which is a descriptor not obviously includable in continuum theory.

  15. Environmental risk assessment system for phosphogypsum tailing dams.

    Science.gov (United States)

    Sun, Xin; Ning, Ping; Tang, Xiaolong; Yi, Honghong; Li, Kai; Zhou, Lianbi; Xu, Xianmang

    2013-01-01

    This paper may be of particular interest to the readers as it provides a new environmental risk assessment system for phosphogypsum tailing dams. In this paper, we studied the phosphogypsum tailing dams which include characteristics of the pollution source, environmental risk characteristics and evaluation requirements to identify the applicable environmental risk assessment methods. Two analytical methods, that is, the analytic hierarchy process (AHP) and fuzzy logic, were used to handle the complexity of the environmental and nonquantitative data. Using our assessment method, different risk factors can be ranked according to their contributions to the environmental risk, thereby allowing the calculation of their relative priorities during decision making. Thus, environmental decision-makers can use this approach to develop alternative management strategies for proposed, ongoing, and completed PG tailing dams.

  16. The relative tail of longevity and the mean remaining lifetime

    Directory of Open Access Journals (Sweden)

    James W. Vaupel

    2006-02-01

    Full Text Available Vaupel (1998 posed the provocative question, "When it comes to death, how do people and flies differ from Toyotas?" He suggested that as the force of natural selection diminishes with age, structural reliability concepts can be profitably used in mortality analysis. Vaupel (2003 went a step further, using simulations to investigate the impact of redundancy, repair capacity, and heterogeneity on the relative length of post-reproductive life spans, called relative tails of longevity. His 2003 paper showed that structural redundancy and the possibility of repair decrease the relative tail of longevity, whereas greater heterogeneity increases it. Here, we consider the problem in much greater generality and prove these results analytically. Structures with repairable and non-repairable components are considered. Heterogeneity is described by a frailty-type model and different definitions of the tail of longevity are discussed.

  17. News from the Library: The 'long tail' Library

    CERN Multimedia

    CERN Library

    2012-01-01

    "The term 'long tail' has gained popularity in recent times as describing the retailing strategy of selling a large number of unique items with relatively small quantities sold of each usually in addition to selling fewer popular items in large quantities. The long tail was popularized by Chris Anderson, who mentioned Amazon.com, Apple and Yahoo! as examples of businesses applying this strategy." *   If we leave the business environment and move to the world of libraries, we still see this "long tail". Usually, only a small portion of a library's book collection accounts for the majority of its loans. On the other hand, there are a variety of "niche information needs" that might not be met, as libraries cannot afford to build up huge collections of documents available just-in-case. However, the networked environment of today's libraries can offer a solution. Online networks of libraries ca...

  18. Lead isotopes as seepage indicators around a uranium tailings dam

    International Nuclear Information System (INIS)

    Gulson, B.L.; Mizon, K.J.; Korsch, M.J.; Noller, B.N.

    1989-01-01

    Lead isotope ratios and lead concentrations have been measured in water from 26 bores around the Ranger uranium tailings dam, Northern Territory, Australia, and from the dam itself to determine possible migration of lead derived from the radioactive decay of uranium. Lead isotope compositions have also been measured for the particulates retained on selected filters. The concentration of lead in the bore waters is extremely low (usually 206 Pb/ 204 Pb ratio measured in the bore waters differs by more than a factor of 100 from that in the tailings dam and shows no evidence of lead derived from a significant uranium accumulation. It may be possible to distinguish between lead from the tailings dam and that derived from a nearby uranium ore body

  19. Recent radiochemistry observations at the Riverton and Maybell tailings piles

    International Nuclear Information System (INIS)

    Smith, A.R.; Moed, B.A.

    1982-09-01

    Preliminary results are presented from the radiochemistry effort of the Lawrence Berkeley Laboratory integrated study of the inactive uranium mill tailings sites at Riverton, Wyoming and Maybell, Colorado. These results were obtained primarily by use of #betta#-ray spectrometric techniques, and included both field and laboratory application of NaI(Tl) crystal and Ge-semiconductor detector systems. Current interpretation of this evidence indicated there has been downward migration of uranium within the tailings column since its emplacement, and upward movement of several radionuclides from the tailings into the overlying cover material. The mechanisms responsible for these migrations are believed to involve fluid transport, and are further believed to be active at the present time

  20. The radiological impacts of uranium mill tailings - A review with special emphasis on the tailings at Ranstad in Sweden

    International Nuclear Information System (INIS)

    Snihs, J.O.

    1978-01-01

    The environmental impact of uranium mill talings can be expressed in collective dose commitment and corresponding detriment per MWe.y energy produced by the uranium which corresponds to the amount of waste interest, The methods of dose commitment calculations are discussed and it is suggested for the purpose of estimation of the detriment to limit the commitment to 10,000 years. The external radiation from the tailings is easily reduced by covering but in case of a future settlement on the tailings the collective dose commitment will be some hundreds to thousands of manrad/MWe.y depending on the quality of the uranium ore. The dispersion of dust from uncovered tailings is mainly a local problem and the collective dose commitment for critical tissues in the lung will be less than a manrad/MWe.y. In the long run the cover may be lost and the resultant collective dose commitment for the critical tissues in the lung will be a few tens of manrad/MWe.y depending on the quality of the tailings. The effects of global dispersion of the material in the tailings are also discussed

  1. Spectral induced polarization (SIP) response of mine tailings.

    Science.gov (United States)

    Placencia-Gómez, Edmundo; Parviainen, Annika; Slater, Lee; Leveinen, Jussi

    2015-02-01

    Mine tailings impoundments are a source of leachates known as acid mine drainage (AMD) which can pose a contamination risk for surrounding surface and groundwater. Methodologies which can help management of this environmental issue are needed. We carried out a laboratory study of the spectral induced polarization (SIP) response of tailings from the Haveri Au-Cu mine, SW Finland. The primary objectives were, (1) to determine possible correlations between SIP parameters and textural properties associated with oxidative-weathering mechanisms, mineralogical composition and metallic content, and (2) to evaluate the effects of the pore water chemistry on SIP parameters associated with redox-inactive and redox-active electrolytes varying in molar concentration, conductivity and pH. The Haveri tailings exhibit well defined relaxation spectra between 100 and 10,000Hz. The relaxation magnitudes are governed by the in-situ oxidative-weathering conditions on sulphide mineral surfaces contained in the tailings, and decrease with the oxidation degree. The oxidation-driven textural variation in the tailings results in changes to the frequency peak of the phase angle, the imaginary conductivity and chargeability, when plotted versus the pore water conductivity. In contrast, the real and the formation electrical conductivity components show a single linear dependence on the pore water conductivity. The increase of the pore water conductivity (dominated by the increase of ions concentration in solution) along with a transition to acidic conditions shifts the polarization peak towards higher frequencies. These findings show the unique sensitivity of the SIP method to potentially discriminate AMD discharges from reactive oxidation zones in tailings, suggesting a significant advantage for monitoring threatened aquifers. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Heavy metal leaching from mine tailings as affected by plants

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, D.; Schwab, A.P.; Banks, M.K.

    1999-12-01

    A column experiment was conducted to determine the impact of soil cover and plants on heavy metal leaching from mine tailings and heavy metal contaminated soil. Columns made of PVC were constructed with 30 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm subsoil covered by 30 cm of mine tailings followed by 0, 30, or 60 cm of clean topsoil. Two grasses, tall fescue (Festuca arundinacea Schreb.) and big bluestem (Andropogon gerardii), were grown in the columns. The columns were leached at a slow rate for 1 yr with a 0.001 M CaCl{sub 2} solution under unsaturated conditions. The presence of both tall fescue and big bluestem increased Zn and Cd concentrations in the leachate. Lead concentrations in leachates were not affected by the presence of plants. Although plants generally reduced the total amount of water leached, total mass of Zn and Cd leached generally was not impacted by plants. Total mass of Pb leached was positively correlated with total leachate collected from each column. Covering the mine tailings with 60 cm of topsoil increased the mass of Zn and Cd leached relative to no topsoil. When the subsoil was absent, Zn and Cd leaching increased by as much as 20-fold, verifying the ability of soil to act as a sink for metals. Mine tailing remediation by establishing vegetation can reduce Pb movement but may enhance short-term Cd and Zn leaching. However, the changes were relatively small and do not outweigh the benefits of using vegetation in mine tailings reclamation.

  3. Long-term stabilization of uranium mill tailings

    International Nuclear Information System (INIS)

    Voorhees, L.D.; Sale, M.J.; Webb, J.W.; Mulholland, P.J.

    1984-01-01

    The primary hazard associated with uranium mill tailings is exposure to a radioactive gas, radon-222, the concentration of which has been correlated with the occurrence of lung cancer. Previous studies on radon attenuation conclude that the placement of earthen cover materials over the tailings is the most effective technique for reducing radioactive emissions and dispersal of tailings. The success of such a plan, however, is dependent on ensuring the long-term integrity of these cover materials. Soil erosion from water and wind is the major natural cause of destabilizing earthen cover materials. Field data related to the control of soil loss are limited and only indirectly apply to the problem of isolation of uranium mill tailings over very long time periods (up to 80,000 a). However, sufficient information is available to determine benefits that will result from changes in specific design variables and to evaluate the need for different design strategies among potential disposal sites. The three major options available for stabilization of uranium mill tailings are (1) rock cover, (2) soil and revegetation, or (3) a combination of both on different portions of the tailings cover. The optimal choice among these alternatives depends on site-specific characteristics such as climate and local geomorphology and soils, and on design variables such as embankment heights and slopes, modification of upstream drainage, and revegetation practices. Generally, geomorphic evidence suggests that use of soil and vegetation alone will not be adequate to reduce erosion on slopes greater than about 5 to 9%. For these steeper slopes, the use of rock talus or riprap will be necessary to maximize the probability of long-term stability. The use of vegetation to control erosion on the flatter portions of the site may be practicable in regions of the USA with sufficient rainfall and suitable soil types, but revegetation practices must be carefully evaluated to ensure that long

  4. Grasping convergent evolution in syngnathids: a unique tale of tails

    Science.gov (United States)

    Neutens, C; Adriaens, D; Christiaens, J; De Kegel, B; Dierick, M; Boistel, R; Van Hoorebeke, L

    2014-01-01

    Seahorses and pipehorses both possess a prehensile tail, a unique characteristic among teleost fishes, allowing them to grasp and hold onto substrates such as sea grasses. Although studies have focused on tail grasping, the pattern of evolutionary transformations that made this possible is poorly understood. Recent phylogenetic studies show that the prehensile tail evolved independently in different syngnathid lineages, including seahorses, Haliichthys taeniophorus and several types of so-called pipehorses. This study explores the pattern that characterizes this convergent evolution towards a prehensile tail, by comparing the caudal musculoskeletal organization, as well as passive bending capacities in pipefish (representing the ancestral state), pipehorse, seahorse and H. taeniophorus. To study the complex musculoskeletal morphology, histological sectioning, μCT-scanning and phase contrast synchrotron scanning were combined with virtual 3D-reconstructions. Results suggest that the independent evolution towards tail grasping in syngnathids reflects at least two quite different strategies in which the ancestral condition of a heavy plated and rigid system became modified into a highly flexible one. Intermediate skeletal morphologies (between the ancestral condition and seahorses) could be found in the pygmy pipehorses and H. taeniophorus, which are phylogenetically closely affiliated with seahorses. This study suggests that the characteristic parallel myoseptal organization as already described in seahorse (compared with a conical organization in pipefish and pipehorse) may not be a necessity for grasping, but represents an apomorphy for seahorses, as this pattern is not found in other syngnathid species possessing a prehensile tail. One could suggest that the functionality of grasping evolved before the specialized, parallel myoseptal organization seen in seahorses. However, as the grasping system in pipehorses is a totally different one, this cannot be

  5. Research on radon flux reduction from uranium mill tailings

    International Nuclear Information System (INIS)

    Overmyer, R.F.; Thamer, B.J.; Nielson, K.K.; Rogers, V.C.

    1980-01-01

    Radon flux reduction from tailings may be accomplished by the use of an impermeable cover to contain the radon until it decays (half life is 2.8 days). The use of a thick, relatively impermeable cover can attenuate radon flux because a large fraction of the radon would decay before it diffuses through the cover into the atmosphere. This method of reducing radon flux may require soil cover thicknesses on the order of 10 feet. In some locations, obtaining 10 feet of soil to cover 200 acres of tailings may be difficult or may lead to other significant environmental impacts. The Department of Energy is sponsoring research to identify alternatives to thick soil covers for reducing radon flux from uranium tailings to meet the forthcoming standards. The two most effective and practical materials tested thus far are Calcilox and asphalt emulsion. Currently, asphalt emulsions are being tested at the Grand Junction tailings pile in Grand Junction, Colorado, by Battelle Pacific Northwest Laboratory. Other asphalt formulations, such as foamed asphalt that requires less water than asphalt emulsions, may be practical and will be tested this year. Some sulfur-based materials and sulfur-extended asphalt also appear promising and will be tested for effectiveness in reducing radon flux. It is also important to investigate methods of applying various stabilizers to inactive tailings piles in various physical conditions of moisture content, and physical stability. Finally, since the EPA standards for remedial action at tailings piles are stated in terms of radon flux, it is important that radon flux measurements be standardized so that reliable flux measurements can be obtained and directly compared among various laboratories

  6. Behaviour of tail-docked lambs tested in isolation

    Directory of Open Access Journals (Sweden)

    Marchewka Joanna

    2016-12-01

    Full Text Available The aims of the current study were to detect behavioural indicators of pain of tail-docked sheep tested in isolation and to determine the relationship between behaviour and the pain levels to which they were exposed. Twenty-four female lambs, randomly assigned to four pens, had their tail docked with a rubber ring (TD; n = 6 without pain control procedures, TD with anaesthesia (TDA; n = 6 or TD with anaesthesia and analgesia (TDAA; n = 6. Additionally, six lambs handled but without tail docking or application of pain relief measures were used as the control (C. On the day prior (Day –1 to the TD and on days 1, 3 and 5 post-procedure, each lamb was individually removed from its group and underwent a 2.5 min open field test in a separate pen. Frequencies of behaviours such as rest, running, standing, walking and exploring were directly observed. Frequencies of exploratory climbs (ECs and abrupt climbs (ACs over the testing pen’s walls were video-recorded. Data were analysed using generalised linear mixed models with repeated measurements, including treatment and day as fixed effects and behaviour on Day –1 as a linear covariate. Control and TDAA lambs stood more frequently than TD lambs. TD lambs performed significantly more ACs compared to all other treatment groups. No other treatment effects were detected. A day effect was detected for all behaviours, while the EC frequency was highest for all tail-docked lambs on Day 5. Findings suggest that standing, ACs and ECs could be used as potential indicators of pain in isolated tail-docked lambs. However, differences in ECs between treatments only appeared 3 d after tail docking.

  7. Research on the characterization and conditioning of uranium mill tailings. III. Summary of uranium mill tailings conditioning research and implications regarding remedial actions

    International Nuclear Information System (INIS)

    Dreesen, D.R.; Cokal, E.J.; Thode, E.F.; Williams, J.M.

    1983-06-01

    This report summarizes the findings of research on uranium mill tailings conditioning technology development performed for the Department of Energy's (DOE) Uranium Mill Tailings Remedial Action Project (UMTRAP). Hazards and risks posed by tailings piles are discussed in relation to the goal of conditioning the tailings to reduce these hazards. The results of our efforts regarding characterization of tailings, removal of radionuclides, mineral recovery, thermal stabilization, and engineering/economic analysis of conditioning are presented. The implications of these results for remedial action plans are discussed and conclusions regarding the applicability of these technologies are also presented

  8. Radiation hazard of solid metallic tailings in Shangluo, China

    OpenAIRE

    Zhuang Sukai; Lu Xinwei; Li Jiantao; Li Qian

    2016-01-01

    The radiation hazards of five kinds of different solid metallic tailings collected from Shangluo, China were determined on the basis of natural radioactivity measurements using low background multichannel gamma ray spectrometry. The activity concentration of 226Ra, 232Th and 40K in the tailings ranged from 5.1 to 204.3, 3.8 to 28.5, and 289.6 to 762.3 Bq/kg, respectively. The radium equivalent activities and the external hazard indexes of all studied metall...

  9. Utilisation of iron ore tailings as aggregates in concrete

    OpenAIRE

    Francis Atta Kuranchie; Sanjay Kumar Shukla; Daryoush Habibi; Alireza Mohyeddin

    2015-01-01

    Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength we...

  10. Uranium Mill Tailings Radiation Control Act of 1978

    International Nuclear Information System (INIS)

    Magee, J.

    1980-01-01

    The long-term environmental effects of the Uranium Mill Tailings Radiation Control Act of 1978 address the public health hazards of radioactive wastes and recognize the significance of this issue to public acceptance of nuclear energy. Title I of the Act deals with stabilizing and controlling mill tailings at inactive sites and classifies the sites by priority. It represents a major Federal commitment. Title II changes and strengthens Nuclear Regulatory Commission authority, but it will have little overall impact. It is not possible to assess the Act's effect because there is no way to know if current technology will be adequate for the length of time required. 76 references

  11. The taxonomic status of the white-tailed kite

    Science.gov (United States)

    Clark, W.S.; Banks, R.C.

    1992-01-01

    The White-tailed Kite (Elanus leucurus) of the Americas has been merged with the Black-shouldered (or Black-winged) Kite (E. caeruleus) of the Old World and the Australian Black-shouldered Kite (E. axillaris) by North American authorities (but not elsewhere), primarily because of similarity in plumage. However, American kites differ from Old World kites in greater size and weight, in proportions (relatively longer tail and smaller bill and feet), plumage pattern (particularly of juveniles), and in behavior. Here we argue that these characters are sufficiently distinctive to warrant recognition of E. leucurus at the species level.

  12. Crops for biodiesel to be grown on mine tailings

    Energy Technology Data Exchange (ETDEWEB)

    Ulrichsen, H.

    2007-12-01

    Natural Resources Canada has launched a feasibility project along with several branches of the federal government, provincial government, Laurentian University and mining and forestry companies to determine if crops suitable for producing biodiesel fuel can be grown on mine tailings. The concept first came about when a biodiesel plant was proposed to be built in Sudbury. Although plans for the plant have been abandoned, the biodiesel crop project is still going ahead. Crops will be cultivated on 2 half-hectare plots on the CVRD Inco tailings in Sudbury, 1 half-hectare plot on the Xstrata Nickel tailings in Sudbury and 1 half-hectare plot on the Goldcorp tailings in Timmins. Paper sludge from St. Marys Paper Company in Sault Ste. Marie and Domtar in Espanola will be spread on the plots in January when the frozen ground is easier to work on with heavy equipment. In the spring, the plots will be seeded with corn, canola or soy, with the possibility of alder and willow in the future. Instruments to monitor groundwater on the sites will also be installed. Biodiesel produced with vegetable or meat oils has been touted as being an environmentally sound diesel fuel. Emissions from vehicles fueled by biodiesel are 40 to 100 per cent lower than those from conventional diesel engines. Proponents of the project emphasize the value of using marginal lands like mine tailings to grow crops for biodiesel fuel instead of prime agricultural land. There are 2,500 hectares of tailings in Sudbury that could be potentially used for this purpose, and about 2,000 hectares at one mine site in Timmins. A Sudbury-area farmer will provide advice about growing the crops and will also grow the same crops on a portion of his land for a comparative evaluation of crop yield. The paper sludge offers the benefit of allowing crops to be grown, but it also cuts off oxygen flow to the tailings underneath, thereby preventing sulphides in the tailings from rusting. The paper sludge may even help the

  13. Interior drains for open pit disposal of uranium mill tailings

    International Nuclear Information System (INIS)

    Staub, W.P.

    1978-01-01

    A conceptualized interior drainage system is presented for reducing the environmental impact on natural groundwater by disposal of uranium mill tailings in the mined-out open pit. The evaporation/seepage ratio can be increased through the use of interior drains, long-term monitoring of groundwater quality can be eliminated, and the open pit will not require an extensive liner. Other advantages not related to groundwater are: control of fugitive dust and radon emanation during mill operations and timely reclamation after the impoundment is filled with tailings

  14. Effect of surface treatment of tailings on effluent quality

    International Nuclear Information System (INIS)

    Murray, D.R.; Okuhara, D.

    1980-01-01

    Lysimeters containing 125 tons of mine tailings were used to determine the impact of gravel, sawdust, and vegetation as surface treatments on the quality and quantity of effluent produced from sulfide-containing uranium mill tailings. Over a 5-yr period, treatments did not alter the effluent quality to a level acceptable to regulatory requirements. The concentration of iron, copper, lead, aluminum, and sulfate increased with the rise of acidity during this period. However, the rate and extent of changes did vary with the treatment. The role of surface treatment in long-term waste abandonment must be investigated further

  15. Wake patterns of the wings and tail of hovering hummingbirds

    Science.gov (United States)

    Altshuler, Douglas L.; Princevac, Marko; Pan, Hansheng; Lozano, Jesse

    The flow fields of slowly flying bats and fasterflying birds differ in that bats produce two vortex loops during each stroke, one per wing, and birds produce a single vortex loop per stroke. In addition, the circulation at stroke transition approaches zero in bats but remains strong in birds. It is unknown if these difference derive from fundamental differences in wing morphology or are a consequence of flight speed. Here, we present an analysis of the horizontal flow field underneath hovering Anna's hummingbirds (Calypte anna) to describe the wake of a bird flying at zero forward velocity. We also consider how the hummingbird tail interacts with the wake generated by the wings. High-speed image recording and analysis from three orthogonal perspectives revealed that the wing tips reach peak velocities in the middle of each stroke and approach zero velocity at stroke transition. Hummingbirds use complex tail kinematic patterns ranging from in phase to antiphase cycling with respect to the wings, covering several phase shifted patterns. We employed particle image velocimetry to attain detailed horizontal flow measurements at three levels with respect to the tail: in the tail, at the tail tip, and just below the tail. The velocity patterns underneath the wings indicate that flow oscillates along the ventral-dorsal axis in response to the down- and up-strokes and that the sideways flows with respect to the bird are consistently from the lateral to medial. The region around the tail is dominated by axial flows in dorsal to ventral direction. We propose that these flows are generated by interaction between the wakes of the two wings at the end of the upstroke, and that the tail actively defects flows to generate moments that contribute to pitch stability. The flow fields images also revealed distinct vortex loops underneath each wing, which were generated during each stroke. From these data, we propose a model for the primary flow structures of hummingbirds that more

  16. Structural implications of the C-terminal tail in the catalytic and stability properties of manganese peroxidases from ligninolytic fungi

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Fueyo, Elena [CSIC, Ramiro de Maeztu 9, 28040 Madrid (Spain); Acebes, Sandra [Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona (Spain); Ruiz-Dueñas, Francisco J.; Martínez, María Jesús; Romero, Antonio; Medrano, Francisco Javier, E-mail: fjmedrano@cib.csic.es [CSIC, Ramiro de Maeztu 9, 28040 Madrid (Spain); Guallar, Victor, E-mail: fjmedrano@cib.csic.es [Barcelona Supercomputing Center, Jordi Girona 29, 08034 Barcelona (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Martínez, Angel T., E-mail: fjmedrano@cib.csic.es [CSIC, Ramiro de Maeztu 9, 28040 Madrid (Spain)

    2014-12-01

    The variable C-terminal tail of manganese peroxidases, a group of enzymes involved in lignin degradation, is implicated in their catalytic and stability properties, as shown by new crystal structures, molecular-simulation and directed-mutagenesis data. Based on this structural–functional evaluation, short and long/extralong manganese peroxidase subfamilies have been accepted; the latter are characterized by exceptional stability, while it is shown for the first time that the former are able to oxidize other substrates at the same site where manganese(II) is oxidized. The genome of Ceriporiopsis subvermispora includes 13 manganese peroxidase (MnP) genes representative of the three subfamilies described in ligninolytic fungi, which share an Mn{sup 2+}-oxidation site and have varying lengths of the C-terminal tail. Short, long and extralong MnPs were heterologously expressed and biochemically characterized, and the first structure of an extralong MnP was solved. Its C-terminal tail surrounds the haem-propionate access channel, contributing to Mn{sup 2+} oxidation by the internal propionate, but prevents the oxidation of 2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), which is only oxidized by short MnPs and by shortened-tail variants from site-directed mutagenesis. The tail, which is anchored by numerous contacts, not only affects the catalytic properties of long/extralong MnPs but is also associated with their high acidic stability. Cd{sup 2+} binds at the Mn{sup 2+}-oxidation site and competitively inhibits oxidation of both Mn{sup 2+} and ABTS. Moreover, mutations blocking the haem-propionate channel prevent substrate oxidation. This agrees with molecular simulations that position ABTS at an electron-transfer distance from the haem propionates of an in silico shortened-tail form, while it cannot reach this position in the extralong MnP crystal structure. Only small differences exist between the long and the extralong MnPs, which do not justify their

  17. Glass ceramic obtained by tailings and tin mine waste reprocessing from Llallagua, Bolivia

    Science.gov (United States)

    Arancibia, Jony Roger Hans; Villarino, Cecilia; Alfonso, Pura; Garcia-Valles, Maite; Martinez, Salvador; Parcerisa, David

    2014-05-01

    In Bolivia Sn mining activity produces large tailings of SiO2-rich residues. These tailings contain potentially toxic elements that can be removed into the surface water and produce a high environmental pollution. This study determines the thermal behaviour and the viability of the manufacture of glass-ceramics from glass. The glass has been obtained from raw materials representative of the Sn mining activities from Llallagua (Bolivia). Temperatures of maximum nucleation rate (Tn) and crystallization (Tcr) were calculated from the differential thermal analyses. The final mineral phases were determined by X-ray diffraction and textures were observed by scanning electron microscopy. Crystalline phases are nefeline occurring with wollastonite or plagioclase. Tn for nepheline is between 680 ºC and 700 ºC, for wollastonite, 730 ºC and for plagioclase, 740 ºC. Tcr for nefeline is between 837 and 965 ºC; for wollastonite, 807 ºC and for plagioclase, 977 ºC. In order to establish the mechanical characteristics and efficiency of the vitrification process in the fixation of potentially toxic elements the resistance to leaching and micro-hardness were determined. The obtained contents of the elements leached from the glass ceramic are well below the limits established by the European legislation. So, these analyses confirm that potentially toxic elements remain fixed in the structure of mineral phases formed in the glass-ceramic process. Regarding the values of micro-hardness results show that they are above those of a commercial glass. The manufacture of glass-ceramics from mining waste reduces the volume of tailings produced for the mining industry and, in turn enhances the waste, transforming it into a product with industrial application. Acknowledgements: This work was partly financed by the project AECID: A3/042750/11, and the SGR 2009SGR-00444.

  18. Removal of 226Ra from tailings pond effluents and stabilization of uranium mine tailings. Bench and pilot scale studies

    International Nuclear Information System (INIS)

    Schmidtke, N.W.; Averill, D.; Bryant, D.N.; Wilkinson, P.; Schmidt, J.W.

    1978-01-01

    Increased world demand for uranium has resulted in recent expansion of Canadian uranium mining operations. Problems have been identified with the discharge of radionuclides such as 226 Ra from tailings pond effluents and with the stabilization of mine tailings. At Environment Canada's Wastewater Technology Centre (WTC) two projects were undertaken in cooperation with the Canadian Uranium Mining Industry and other federal government agencies to address these problems. The first project reports on the progress of bench and pilot scale process simulations for the development of a data base for the design of a full scale mechanical physical/chemical 226 Ra removal waste treatment system with an effluent target level of 10 pCi 226 Ra total per litre. The second project addresses problems of the leachability of radionuclides and the stabilization of both uranium mine tailings and BaRaSO 4 sediments from the treatment of acid seepages

  19. Mutational analysis of two structural genes of the remperate lactococcal bacteriophage TP901-1 involved in tail length determination and baseplate assembly

    DEFF Research Database (Denmark)

    Pedersen, Margit; Østergaard, Solvej; Bresciani, José

    2000-01-01

    Two putative structural genes, orf tmp (tape measure protein) and orf bpp (baseplate protein), of the temperate lactococcal phage TP901-1 were examined by introduction of specific mutations in the prophage strain Lactococcus lactic ssp. cremoris 901-1. The adsorption efficiencies of the mutated...... or duplication of 29% in orf tmp was shown to shorten or lengthen the phage tail by approximately 30%, respectively. The orf tmp is proposed to function as a tape measure protein, TMP, important for assembly of the TP901-1 phage tail and involved in tail length determination. Specific mutations in orf bpp...... produced phages which were unable to adsorb to the indicator strain and electron microscopy revealed particles lacking the baseplate structure. The orf bpp is proposed to encode a highly immunogenic structural baseplate protein, BPP, important for assembly of the baseplate. Finally, an assembly pathway...

  20. The uranium mine Key Lake, Canada, as an example of final deposition of radioactive tailings

    International Nuclear Information System (INIS)

    Schmitz, T.

    1984-01-01

    The main part of that waste handling system is tailing storage. The other parts include the water storage reservoirs and monitoring ponds. Soil conditions and design features of the tailings pond are described in detail as well as the method of tailings disposal. Finally the method of deposition results in a laminated radioactive tailings deposit and the tailings reach a degree of compactness comparable to concrete. The Key Lake Mining Corporation and its consultants have developed a tailings handling program in order to minimize environmental impact and to take advantage of the natural topography and soil materials in the project area. (orig./HP) [de

  1. Can tail damage outbreaks in the pig be predicted by behavioural change?

    DEFF Research Database (Denmark)

    Larsen, Mona Lilian Vestbjerg; Andersen, Heidi Mai-Lis; Pedersen, Lene Juul

    2016-01-01

    preventive methods. One strategy is the surveillance of the pigs' behaviour for known preceding indicators of tail damage, which makes it possible to predict a tail damage outbreak and prevent it in proper time. This review discusses the existing literature on behavioural changes observed prior to a tail...... damage outbreak. Behaviours found to change prior to an outbreak include increased activity level, increased performance of enrichment object manipulation, and a changed proportion of tail posture with more tails between the legs. Monitoring these types of behaviours is also discussed for the purpose......, starting with the description of the temporal development of the predictive behaviour in relation to tail damage outbreaks...

  2. Removal of radioactivity and mineral values from uranium mill tailings

    International Nuclear Information System (INIS)

    Williams, J.M.; Cokal, E.J.; Dreesen, D.R.

    1981-01-01

    One possible approach to remedial action on uranium mill tailings involves the removal of the components that are responsible for the environmental concern (notably radon releases) posed by these materials. Removing mineral values at the same time can defray much of the cost. This paper presents laboratory results on sulfuric acid leachings and their effectiveness in accomplishing these aims. 9 figures, 4 tables

  3. Analysis of infiltration through mill tailings using a bromide tracer

    International Nuclear Information System (INIS)

    Lewis, G.J.; Stephens, D.B.

    1985-01-01

    Infiltration of precipitation into tailings impoundments as a means of recharge to underlying materials is often considered insignificant, particularly in arid and semi-arid environments. A series of experiments was performed to investigate the behavior of infiltrated precipitation into tailing soils, by the use of a bromide tracer. A bromide tracer was applied to the surface of columns driven into the tailings to monitor downward advancement of tracer-laden water. Controlled laboratory experiments on the behavior of the bromide tracer under varying precipitation events and initial soil moisture contents were also conducted. Results indicate that a definite downward migration of infiltrated precipitation occurs, particularly with large magnitude precipitation events, and that, eventually, some fraction of the infiltrated precipitation may continue downward below the zone affected by evaporation. The use of an artificially applied bromide tracer to monitor depth of infiltration of precipitation is a simple, safe technique that can provide valuable information for long-term tailings management strategies at low cost

  4. Limit Cycle Behaviour of the Bump-on-Tail Instability

    DEFF Research Database (Denmark)

    Janssen, P. A. E. M.; Juul Rasmussen, Jens

    1981-01-01

    The nonlinear dynamics of the bump‐on‐tail instability is considered. The eigenmodes have discrete k because of finite periodic boundary conditions. Increasing a critical parameter (the number density) above its neutral stable value by a small fractional amount Δ2, one mode becomes unstable...

  5. Random matrix theory for heavy-tailed time series

    DEFF Research Database (Denmark)

    Heiny, Johannes

    2017-01-01

    This paper is a review of recent results for large random matrices with heavy-tailed entries. First, we outline the development of and some classical results in random matrix theory. We focus on large sample covariance matrices, their limiting spectral distributions, the asymptotic behavior...

  6. Bias-corrected estimation of stable tail dependence function

    DEFF Research Database (Denmark)

    Beirlant, Jan; Escobar-Bach, Mikael; Goegebeur, Yuri

    2016-01-01

    We consider the estimation of the stable tail dependence function. We propose a bias-corrected estimator and we establish its asymptotic behaviour under suitable assumptions. The finite sample performance of the proposed estimator is evaluated by means of an extensive simulation study where...

  7. Trace elements contamination of soils around gold mine tailings ...

    African Journals Online (AJOL)

    ISHIOMA

    Soil samples taken from depths of up to 12 cm and within a radius of 400 m from the ... Key words: Gold mining, tailings dam, trace elements, soil, Obuasi. INTRODUCTION ..... through soil might take considerably long time to manifest, probably ...

  8. The utilization of forward osmosis for coal tailings dewatering

    Science.gov (United States)

    The feasibility of dewatering coal tailings slurry by forward osmosis (FO) membrane process was investigated in this research. A prototype cell was designed and used for the dewatering tests. A cellulosic FO membrane (Hydration Technology Innovations, LLC, Albany, OR) was used fo...

  9. Diets of black-tailed hares on the Hanford Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Uresk, D.W.; Cline, J.F.; Rickard, W.H.

    1975-04-01

    A fecal pellet analyses showed that black-tailed hares (jackrabbits) were selective in plants chosen as food. The most abundant herbaceous plant, cheatgrass, was not found in the pellets. Sagebrush and bitterbrush, woody plants, were not an important part of the hares' diet. Forbs, rabbitbrush, and certain grass species were preferred foods. (auth)

  10. A study of bauxite tailing quality improvement by reverse flotation

    Science.gov (United States)

    Wulandari, W.; Purwasasmita, M.; Sanwani, E.; Malatsih, W.; Fadilla, F.

    2018-01-01

    The pre-treatment of bauxite ore from Tayan, West Kalimantan includes washing and screening fine bauxite particles (-2mm) prior as the feed to the Bayer process for producing alumina. These fine particles are believed to have high content of silica which is detrimental to the process. This washed bauxite tailing still has a significant amount of alumina content. Previous research has indicated that bauxite ore can be upgraded by applying reverse flotation method to reduce its silica content in the ore. Therefore, this study is aimed to utilize reverse flotation method to recover alumina content from washed bauxite tailing. The reverse flotation experiments were carried out at pH of 6 and 8; while the particle sizes were varied at - 140+270 mesh and -270 mesh, using a batch and circuit configuration. The result of this study shows that the batch reverse flotation can recover alumina in the tailing up to 81.4%, however the silica content is still significant. The complexity of silica-alumina minerals in the tailing prevents a complete separation of the ores by only using reverse flotation.

  11. Autotomy, tail regeneration and jumping ability in Cape dwarf ...

    African Journals Online (AJOL)

    Many studies have examined the effect of caudal autotomy on speed and ... Although longer jumps were less likely to be successful (i.e. the animal ... Their tails may, however, be important to control their landing as well as their locomotion on ...

  12. Bounds for Tail Probabilities of the Sample Variance

    Directory of Open Access Journals (Sweden)

    Van Zuijlen M

    2009-01-01

    Full Text Available We provide bounds for tail probabilities of the sample variance. The bounds are expressed in terms of Hoeffding functions and are the sharpest known. They are designed having in mind applications in auditing as well as in processing data related to environment.

  13. Moisture content analysis of covered uranium mill tailings

    International Nuclear Information System (INIS)

    Mayer, D.W.; Beedlow, P.A.; Cadwell, L.L.

    1981-12-01

    The use of vegetation and rock covers to stabilize uranium mill tailings cover systems is being investigated by Pacific Northwest Laboratory. A modeling study of moisture movement through the tailings and cover layers was initiated to determine the effect of the stabilizing techniques. The cover system was simulated under climatic conditions occurring at Grand Junction, Colorado. The cover consisted of a layer of wet clay/gravel mix followed by a capillary barrier of washed rock and a surface layer of fill soil. Vegetation and rock were used to stabilize the surface layer. The simulation yielded moisture content and moisture storage values for the tailings and cover system along with information about moisture losses due to evaporation, transpiration, and drainage. The study demonstrates that different surface stabilization treatments lead to different degrees of moisture retention in the covered tailings pile. The evapotranspiration from vegetation can result in a relatively stable moisture content. Rock covers, however, may cause drainage to occur because they reduce evaporation and lead to a subsequent increase in moisture content. It is important to consider these effects when designing a surface stabilization treatment. Drainage may contribute to a groundwater pollution problem. A surface treatment that allows the cover system to dry out can increase the risk of atmospheric contamination through elevated radon emission rates

  14. Body extract of tail amputated zebrafish promotes culturing of ...

    African Journals Online (AJOL)

    HJE

    study on the interaction between primary fin cells from glass catfish and tail ... These results provide an essential knowledge base for rational approaches to tissue and ... cultured in DMEM with 1% P/S and 10% (v/v) fetal bovine serum.

  15. Long memory and tail dependence in trading volume and volatility

    DEFF Research Database (Denmark)

    Rossi, Eduardo; Santucci de Magistris, Paolo

    2013-01-01

    We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations...

  16. Architecture and environmental restoration: Remediating uranium mill tailings from buildings

    International Nuclear Information System (INIS)

    Teply, J.D.

    1991-01-01

    The US Department of Energy (DOE) Grand Junction Projects Office (GJPO) manages the Uranium Mill Tailings Remedial Action (UMTRA) Program in Grand Junction, Colorado. This program is a congressionally mandated clean up of by-product waste that resulted from the extraction of yellow cake from uranium ore. The by-product waste, a fine sand commonly called open-quotes mill tailingclose quotes is contaminated with low-level radioactivity. These mill tailings were available to the community for use as construction material from approximately 1952 to 1966; their use as bedding material for concrete slabs, utilities, backfill materials, concrete sand, and mortar created unique remediation problems that required innovative solutions. This paper describes how design personnel approach the remediation of structures, the evaluation of the buildings, and the factors that must be considered in completing the remediation design. This paper will not address the health risks of the tailings in an inhabited space, the remediation of exterior areas, or the process of determining where the tailings exist in the building

  17. Gold tailings as a source of waterborne uranium contamination of ...

    African Journals Online (AJOL)

    driniev

    2004-04-02

    Apr 2, 2004 ... Dissolved uranium (U) from the tailings deposits of various gold mines in South Africa has .... tivity), probes for measuring hydro-chemical (pH, Eh), physical ... Due to the pumping scheme, rain events in the catchment do not.

  18. Taxonomic variation in oviposition by tailed frogs (Aschaphus spp.).

    Science.gov (United States)

    Nancy E. Karraker; David S. Pilliod; Michael J. Adams; Evelyn L. Bull; Paul Stephen Corn; Lowell V. Diller; Linda A. Dupuis; Marc P. Hayes; Blake R. Hossack; Garth R. Hodgson; Erin J. Hyde; Kirk Lohman; Bradford R. Norman; Lisa M. Ollivier; Christopher A. Pearl; Charles R. Peterson

    2006-01-01

    Tailed frogs (Ascaphus spp.) oviposit in cryptic locations in streams of the Pacific Northwest and Rocky Mountains. This aspect of their life history has restricted our understanding of their reproductive ecology. The recent split of A. montanus in the Rocky Mountains from A. truei was based on molecular...

  19. A tail bound for read-k families of functions

    Czech Academy of Sciences Publication Activity Database

    Gavinsky, Dmitry; Lovett, S.; Saks, M.; Srinivasan, S.

    2015-01-01

    Roč. 47, č. 1 (2015), s. 99-108 ISSN 1042-9832 Institutional support: RVO:67985840 Keywords : tail bound * deviation bound * random variables Subject RIV: BA - General Mathematics Impact factor: 1.011, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/ rsa .20532/abstract

  20. Do different subspecies of Black-tailed Godwit

    NARCIS (Netherlands)

    Lopes, R.J.; Alves, J.A.; Gill, J.A.; Gunnarsson, T.G.; Hooijmeijer, J.C.E.W.; Lourenço, P.M.; Masero, J.A.; Piersma, T.; Potts, P.M.; Rabaçal, B.; Reis, S.; Sánchez-Guzmán, J.M.; Santiago-Quesada, F.; Villegas, A.

    2013-01-01

    Resolving the migratory connectivity (identifying non-breeding grounds) of migrating bird populations that are morphologically similar is crucial for an understanding of their population dynamics and ultimately their conservation. Such is the case in Black-tailed Godwits Limosa limosa, where the