Signature of a universal statistical description for drift-wave plasma turbulence

This Letter provides a theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events. Specifically, nonlinear gyrokinetic simulations of ion-temperature-gradient turbulence produce time series of heat flux which exhibit manifestly non-Gaussian PDFs with enhanced tails. It is demonstrated that, after the removal of autocorrelations, the numerical PDFs can be matched with predictions from a fluid theoretical setup, based on the instanton method. This result points to a universality in the modeling of intermittent stochastic process, offering predictive capability.Comment: 4 pages, 5 figure

La kanemite, nouveau silicate de sodium hydraté de néoformation

Kanemite, NaH [Si₂O₄ (OH)₂] • 2H₂O, was found, associated with trona and gaylussite in the interdunary depression of Andjia, on the northeastern edge of Chad Lake. Orthorhombic, D [2h] ⁷˗Pnmb, a₀ = 7.282, b₀ = 20.507, c₀ = 4.956 Å ; V = 740 Å³ ; Z = 4 ; ρcalc. = 1.933. Strongest lines of the X-ray powder pattern are : 10.3 (10), 4.014 (10), 3.435 (9) ; 3.162 (7), 3.093 (7), 2.480 (8) Å. Biaxial (— ), 2 V = 46°, ng = 1.478 (c), nm = 1.470 (a), np = 1.451 (b) ; dispersion r > v. White spherolites and platy crystals with (010) ; cleavage (010) perfect, (100) good ; hardness 4 ; ρmeas. = 1.926. Chemical composition : SiO₂ = 56.68, Al₂O₃ = 0.40, CaO = 0.20, Na₂O = 13.25, K₂O = 0,10, H₂O (> 280°) = 4.25, H₂O (170°-280°) = 8.45, H₂O (170°) = 16.30, total = 99.63. Differential thermal analysis shows sharp endothermic peaks at 160°, 220°, 600° C and a broad exothermic peak at 655° C. The products of dehydration have been studied. IR spectrum shows absorption bands at 3570, 3445, 1667, 1475, 1170, 1046, 900, 850, 774, 681, 609, 659 and 456 cm⁻¹. The name is taken from Kanem, the region where the salina is located.La kanemite, NaH [Si₂O₄ (OH)₂] • 2H₂O, a été trouvée dans la saline d'Andjia, Kanem, au Tchad, associée au trona et à la gaylussite. Orthorhombique, D [2h] ⁷˗Pnmb, a₀ = 7,282, b₀ = 20,507, c₀ = 4,956 Å ; V = 740 Å³ ; Z = 4 ; dx = 1,933. Les raies les plus intenses du diagramme de poudre sont : 10,3 (10), 4,014 (10), 3,435 (9), 3,162 (7), 3,093 (7), 2,480 (8) Å. Biaxe (— ), 2 V = 46°, ng = 1,478 (c), nm = 1,470 (a), np = 1,451 (b) ; dispersion r > v. En sphérolites blancs et en cristaux aplatis suivant (010) ; clivage (010) parfait, (100) bon ; dureté ~ 4 ; d[mes.] = 1,926. Composition chimique : SiO₂ = 56,68, Al₂O₃ = 0,40, CaO = 0,20, Na₂O = 13,25, K₂O = 0,10, H₂O (> 280°) = 4,25, H₂O (170°-280)° = 8,45, H₂O (170°) = 16,30, total = 99,63. L'ATD montre des maximums endothermiques à 160°, 220°, 600° C et un maximum exothermique à 655° C. Le spectre d'absorption infrarouge donne les bandes suivantes : 3570, 3445, 1667, 1475, 1170, 1046, 900, 850, 774, 681, 609, 569 et 456 cm⁻¹. Le minéral est nommé d'après la région de Kanem où est situé le gisement type.Johan Zdenek, Maglione Gilbert. La kanemite, nouveau silicate de sodium hydraté de néoformation. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 95, 3, 1972. pp. 371-382

The momentum flux probability distribution function for ion-temperature-gradient turbulence

There has been overwhelming evidence that coherent structures play a critical role in determining the overall transport in a variety of systems. We compute the probability distribution function (PDF) tails of momentum flux and heat flux in ion-temperature-gradient turbulence, by taking into account the interaction among modons, which are assumed to be coherent structures responsible for bursty and intermittent events, contributing to the PDF tails. The tail of PDF of momentum flux R = 〈vxvy〉 is shown to be exponential with the form exp{−ξR3/2}, which is broader than a Gaussian, similar to what was found in the previous local studies. An analogous expression with the same functional dependence is found for the PDF tails of heat flux. Furthermore, we present a detailed numerical study of the dependence of the PDF tail on the temperature and density scale lengths and other physical parameters through the coefficient ξ

Minimal model for spoof acoustoelastic surface states

Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simulations confirm the feasibility of the model and we demonstrate illustrative examples such as resonant transmissions and waveguiding to show a few examples of many where spoof elastic surface waves are useful

Non-perturbative statistical theory of intermittency in ITG drift wave turbulence with zonal flows

The probability distribution functions (PDFs) of momentum flux and zonal flow formation in ion-temperature-gradient (ITG) turbulence are investigated in two different models. The first is a general five-field model (ni, , Ti, Te, vi) where a reductive perturbation method is used to derive dynamical equations for drift waves and a zonal flow. The second is a reduced two-field model (, Ti) that has an exact non-linear solution (bipolar vortex soliton). In both models the exponential tails of the zonal flow PDFs are found with the same scaling ( ), but with different coefficients cZF. The PDFs of momentum flux is, however, found to be qualitatively different with the scaling (PDF ~ exp{−cMRs}), where s = 2 and s = 3/2 in the five and two-field models, respectively

Constraining General Two Higgs Doublet Models by the Evolution of Yukawa Couplings

We study how general two Higgs doublet models can be constrained by considering their properties under renormalization group evolution of the Yukawa couplings. We take into account both the appearance of a Landau pole as well as off-diagonal Yukawa couplings leading to flavour changing neutral currents in violation with experimental constraints at the electroweak scale. We find that the latter condition can be used to limit the amount of Z2 symmetry breaking allowed in a given model.Comment: 28 pages, 10 figures, added discussion of evolution from high to low scales, to be published in JHE

The Progenitors of Local Ultra-massive Galaxies Across Cosmic Time: from Dusty Star-bursting to Quiescent Stellar Populations

Using the UltraVISTA catalogs, we investigate the evolution in the 11.4~Gyr since $z=3$ of the progenitors of local ultra-massive galaxies ($\log{(M_{\rm star}/M_{\odot})}\approx11.8$; UMGs), providing a complete and consistent picture of how the most massive galaxies at $z=0$ have assembled. By selecting the progenitors with a semi-empirical approach using abundance matching, we infer a growth in stellar mass of 0.56$^{+0.35}_{-0.25}$ dex, 0.45$^{+0.16}_{-0.20}$~dex, and 0.27$^{+0.08}_{-0.12}$ dex from $z=3$, $z=2$, and $z=1$, respectively, to $z=0$. At $z<1$, the progenitors of UMGs constitute a homogeneous population of only quiescent galaxies with old stellar populations. At $z>1$, the contribution from star-forming galaxies progressively increases, with the progenitors at $2<z<3$ being dominated by massive ($M_{\rm star} \approx 2 \times 10^{11}$M$_{\odot}$), dusty ($A_{\rm V}\sim$1--2.2 mag), star-forming (SFR$\sim$100--400~M$_{\odot}$ yr$^{-1}$) galaxies with a large range in stellar ages. At $z=2.75$, $\sim$15\% of the progenitors are quiescent, with properties typical of post-starburst galaxies with little dust extinction and strong Balmer break, and showing a large scatter in color. Our findings indicate that at least half of the stellar content of local UMGs was assembled at $z>1$, whereas the remaining was assembled via merging from $z\sim 1$ to the present. Most of the quenching of the star-forming progenitors happened between $z=2.75$ and $z=1.25$, in good agreement with the typical formation redshift and scatter in age of $z=0$ UMGs as derived from their fossil records. The progenitors of local UMGs, including the star-forming ones, never lived on the blue cloud since $z=3$. We propose an alternative path for the formation of local UMGs that refines previously proposed pictures and that is fully consistent with our findings.Comment: 20 pages, 15 figures (6 of which in appendix); accepted for publication in the Astrophysical Journa