An Analytical APproach to the Turbulence—Relaxed State in Tokamak Plasmas

Starting from the continuity, temperature, and motion equations of the trapped electron fluid in general tokamak magnetic field with positive or reversed shear and the definition of Lagrangian invariant, dL/dt≡(\partial_t+ u•▽)L=0, where u is convective velocity, the trapped electron dynamics is considered in the following two assumptions: (i) the turbulence is low frequency electrostatic, and (ii) L is a functional only of the density n, temperature T, and magnetic field B, and the effect of perturbation potential φ is included in the convective velocity u, i.e., u is a functional of n, T, B, and φ. The Lagrangian invariant hidden in the trapped electron dynamics is strictly found: L=ln[(n/B)^c₁(T/B^2/3)^c₂], where c₁ and c₂ are dimensionless changeable parameters and c₁∝c₂. From this Lagrangian invariant the turbulent particle and electron thermal transport scaling laws are derived: 〈n>_ψq(ψ)=const. and 〈T^3/2>_ψq(ψ)=const., which, in the limit of large aspect ratio, reduce to n(r)q(r)=const. and T^3/2(r)q(r)=const., respectively. The latter two scaling laws are compared with existent experimental results, being in good agreement.     

Effects of a parallel magnetic field on the metal-insulator transition in a dilute two-dimensional electron system

The temperature dependence of conductivity sigma(T) of a two-dimensional electron system in silicon has been studied in parallel magnetic fields B. At B = 0, the system displays a metal-insulator transition at a critical electron density n(c)(0), and dsigma/dT>0 in the metallic phase. At low fields ( B < or approximately equal to 2 T), n(c) increases as n(c)(B)-n(c)(0) proportional, variant Bbeta ( beta approximately 1), and the zero-temperature conductivity scales as sigma(n(s),B,T = 0)/sigma(n(s),0,0) = f(B(beta)/delta(n)), where delta(n) = [n(s)-n(c)(0)]/n(c)(0) and n(s) is electron density, as expected for a quantum phase transition. The metallic phase persists in fields of up to 18 T, consistent with the saturation of n(c) at high fields.     

Internal kink instability during off-axis electron cyclotron current drive in the DIII-D tokamak

Experimental evidence is reported of an internal kink instability driven by a new mechanism: barely trapped suprathermal electrons produced by off-axis electron cyclotron heating on the DIII-D tokamak. It occurs in plasmas with an evolving safety factor profile q(r) when q(min) approaches 1. This instability is most active when ECCD is applied on the high field side of the flux surface. It has a bursting behavior with poloidal/toroidal mode number = m/n = 1/1. In positive magnetic shear plasmas, this mode becomes the fishbone instability. This observation can be qualitatively explained by the drift reversal of the barely trapped suprathermal electrons.     

Field dependence of the muon spin relaxation rate in MnSi

Muon spin rotation/relaxation measurements have been performed in the itinerant helical magnet MnSi at ambient pressure and at 8.3 kbar. We have found the following: (a) the spin-lattice relaxation rate 1/T(1) shows divergence as T1T proportional, variant (T-T(c))(beta) with the power beta larger than 1 near T(c); (b) 1/T(1) is strongly reduced in an applied external field B(L) and the divergent behavior near T(c) is completely suppressed at B(L)> or =4000 G. We discuss that (a) is consistent with the self-consistent renormalization theory and reflects a departure from "mean-field" behavior, while (b) indicates selective suppression of spin fluctuations of the q=0 component by B(L).     

Determination of /Vub/ from measurements of the inclusive charmless semileptonic partial rates of B mesons using full reconstruction tags

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element /Vub/, based on 253 fb(-1) of data collected by the Belle detector at the KEKB e+ e- asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from Gamma(4S). The signal for b --> u semileptonic decay is distinguished from the b --> c background using the hadronic mass Mx, the leptonic invariant mass squared q2 and the variable P+ [triple bond] Ex - /px/. The results are obtained for events with p(l)* > or = 1 GeV/c, in three kinematic regions (1) Mx < 1.7 GeV/c2, (2) Mx < 1.7 GeV/c2 combined with q2 > 8 GeV2/c2, and by (3) P+ < 0.66 GeV/c. The matrix element /Vub/ is found to be (4.09 +/- 0.19 +/- 0.20(+0.14) -0.15 +/- 0.18) x 10(-3), where the errors are statistical, systematic including Monte Carlo modeling, theoretical, and from shape function parameter determination, respectively.     

Gauge Supergravities for All Odd Dimensions

Recently proposed supergravity theories in odddimensions whose fields are connection one-forms for theminimal supersymmetric extensions of anti-de Sittergravity are discussed. Two essential ingredients are required for this construction: (1) Thesuperalgebras, which extend the adS algebra fordifferent dimensions, and (2) the Lagrangians, which areChern-Simons (2n - 1)-forms. The first item completes the analysis of van Holten and Van Proeyen,which was valid for N = 1 only. The second ensures thatthe actions are invariant by construction under thegauge supergroup and, in particular, under localsupersymmetry. Thus, unlike standard supergravity, the localsupersymmetry algebra closes off-shell and withoutrequiring auxiliary fields. The superalgebras areconstructed for all dimensions and they fall into three families: osp (m|N) for D = 2, 3, 4, mod 8, osp(N|m) for D = 6, 7, 8, mod 8, and su(m - 2, 2|N) for D= 5 mod 4, with m = 2^[D/2]. The Lagrangian isconstructed for D = 5, 7, and 11. In all cases the field content includes the vielbein(e ^a ), the spin connection( ^ab ), N gravitini( ⁱ ), and some extrabosonic "matter" fields which vary from onedimension to another.     

Absence of long-range order with long-range potentials

A particular form of Mermin's inequality is analyzed for repulsive inverse power potentials [V(r)=e ² r ^–m/m] in ad-dimensional space. For long-range potentials (m d) the system is put into a stabilizing background. Long-range order is shown to be excluded ford (m + 2)/2 whenm d, while for short-range potentials (m > d) we recover Mermin's result (d 2). For Coulomb systems (m=d – 2) and the experimentally studied electron surface layer (d = 2,m=1), long-range order cannot be excluded by the present argument.     

Gauge invariant Lagrangian construction for massive higher spin fermionic fields

We formulate a general gauge invariant Lagrangian construction describing the dynamics of massive higher spin fermionic fields in arbitrary dimensions. Treating the conditions determining the irreducible representations of Poincaré group with given spin as the operator constraints in auxiliary Fock space, we built the BRST charge for the model under consideration and find the gauge invariant equations of motion in terms of vectors and operators in the Fock space. It is shown that like in massless case [I.L. Buchbinder, V.A. Krykhtin, A. Pashnev, Nucl. Phys. B 711 (2005) 367, hep-th/0410215], the massive fermionic higher spin field models are the reducible gauge theories and the order of reducibility grows with the value of spin. In compare with all previous approaches, no off-shell constraints on the fields and the gauge parameters are imposed from the very beginning, all correct constraints emerge automatically as the consequences of the equations of motion. As an example, we derive a gauge invariant Lagrangian for massive spin 3/2 field.     

Global gyrokinetic stability of pressure-gradient-driven electromagnetic modes in tokamaks with regions of low shear

Tokamaks with large pressure gradients (alpha(max)) formed in regions of weak magnetic shear are shown to be susceptible to novel, low-n, global, kinetic, electromagnetic modes with a toroidal mode number n in the range 21 on the magnetic axis and alpha(max) near q(min), new, global kinetic infernal modes with a strong mode rotation omega(r) and a finite growth rate gamma<|omega(r)| are found. For equilibria with reverse shear where q(min) is off axis and alpha(max) near q(min), the existence of an unstable low-n global branch of Alfve n ion temperature gradient modes is revealed with an oscillatory gamma as a function of n. The addition of trapped electron dynamics is shown to be further destabilizing.     

Quantification of Effector Binding to the Hemoglobin Central Cavity by Intrinsic and Extrinsic Steady-State Fluorescence

The relative intrinsic and extrinsic fluorescence of hemoglobins are established markers of the R (oxy) T (deoxy) transition and reveal site-specific conformational differences amongst hemoglobin (Hb) mutants. The Hb central cavity has been probed by binding the fluorescent analogue of 2,3-diphosphoglycerate, 8-hydroxy-1,3,6-pyrenetrisulfonate (HPT). An approach to quantify binding of HPT to HbC (6 Lys) and HbA (6 Glu), by steady-state front-face fluorescence spectroscopy using both the intrinsic and extrinsic emissions, is presented. When HPT specifically binds to Hb, efficient fluorescence energy transfer from the intrinsic fluorescence of Hb to HPT occurs, decreasing the intrinsic fluorescence of Hb that plateaus upon stoichiometric binding. HPT fluorescence is significantly but not totally quenched upon binding to HbA and HbC. HPT exhibits a molecular binding ratio of 2:1 to HbC, in contrast to HbA (1:1 binding). The apparent secondary binding site for HbC is weaker (K_D1 = 25 M vs. K_D2 = 0.15 mM). Conformational alterations of HbC at the and clefts of the central cavity are further supported by these data.     

Direct and Inverse Cascades in Two-DimensionalTurbulence with a Generalized Enstrophy Invariant

Direct and reverse cascades are shown to be generic to two-dimensional turbulencewith a generalized enstrophy invariant Ü = 1/2|^2q|² dx = const, q 1/2. Theclassical hydrodynamical situation is a special case (q = 1) of thegeneral result.     

Symmetries of Schrödinger Operator with Point Interactions

The transformations of all the Schrödinger operators with point interactions in dimension one under space reflection P, time reversal T and (Weyl) scaling W are presented. In particular, those operators which are invariant (possibly up to a scale) are selected. Some recent papers on related topics are commented upon.     

Measurements of partial branching fractions for B-->Xulnu and determination of |Vub|

We present partial branching fractions for inclusive charmless semileptonic B decays B[over ]-->X_{u}lnu[over ], and the determination of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}|. The analysis is based on a sample of 383 x 10;{6} Upsilon(4S) decays into BB[over ] pairs collected with the BABAR detector at the SLAC PEP-II e;{+}e;{-} storage rings. We select events using the invariant mass M_{X} of the hadronic system, the invariant mass squared, q;{2}, of the lepton and neutrino pair, the kinematic variable P+, or one of their combinations. We then determine partial branching fractions in limited regions of phase space: DeltaB=(1.18+/-0.09_{stat}+/-0.07_{syst}+/-0.01_{theor})x10;{-3} (M_{X}<1.55 GeV/c;{2}), DeltaB=(0.95+/-0.10_{stat}+/-0.08_{syst}+/-0.01_{theor})x10;{-3} (P+<0.66 GeV/c), and DeltaB=(0.81+/-0.08_{stat}+/-0.07_{syst}+/-0.02_{theor})x10;{-3} (M_{X}<1.7 GeV/c;{2}, q;{2}>8 GeV;{2}/c;{4}). Corresponding values of |V_{ub}| are extracted using several theoretical calculations.     

The effect of a magnetic flux line in quantum theory

The nonlocal exchange of the conserved, gauge invariant quantity e (i/variant Planck's) (p(k)-(e/cA(k))L(k)), L(k)=const, k=1,2 between the charged particle and the magnetic flux line (in the k=3 direction) is responsible for the Aharonov-Bohm effect. This exchange occurs at a definite time, before the wave packets are brought together to interfere, and can be verified experimentally.     

Singular perturbations of piecewise monotonic maps of the interval

Let t: [0, 1] [0, 1] be a piecewise monotonic, C₂, and expanding map. In computing an orbit { ⁱ (x ₀)} _i=0 , we model the roundoff error at each iteration by a singular perturbation; i.e.,X _n+1=(X _n )+W , whereW is a random variable taking on discrete values in an interval (-&#x03B5;, ). The main result proves that this process admits an absolutely continuous invariant measure which approaches the absolutely continuous measure invariant under the deterministic map t as the precision of computation 0.     

On nonquasineutrality and turbulent heat transfer in a tokamak

A new approach is proposed for describing a steady turbulent state formed far from thermodynamic equilibrium in the plasma column of a tokamak as a result of the development of microinstabilities. A fundamental feature of such a highly nonequilibrium plasma is its nonquasineutrality, i.e., the plasma properties are largely determined by electric fields localized on a scale of the order of the Debye radius. It is established that the transverse thermal diffusivity is determined by the expression

Neutral pion production in d-Au collisions at \sqrt{s_{NN}} = 200 GeV

In this paper, preliminary results are presented on high inclusive neutral pion measurements in d-Au collisions at GeV in the pseudo-rapidity range . Photons from the decay are detected in the Barrel Electromagnetic Calorimeter of the STAR experiment at RHIC. The analysis of this first BEMC hadron measurement is described in detail. The results are compared to earlier RHIC findings. Furthermore, the obtained invariant differential cross sections show good agreement with next-to-leading order (NLO) perturbative QCD calculations. Arrival of the final proofs: 4 July 2005 PACS: 25.75.-q     

Dynamic structure factor in a random diffusion model

Let {X _t:0} denote random walk in the random waiting time model, i.e., simple random walk with jump ratew ^–1(X _t), where {w(x):x^d} is an i.i.d. random field. We show that (under some mild conditions) theintermediate scattering function F(q,t)=E ₀ (q^d) is completely monotonic int (E ₀ denotes double expectation w.r.t. walk and field). We also show that thedynamic structure factor S(q, w)=2 ₀ cos(t)F(q, t) exists for 0 and is strictly positive. Ind=1, 2 it diverges as 1/||^1/2, resp. –ln(||), in the limit 0; ind3 its limit value is strictly larger than expected from hydrodynamics. This and further results support the conclusion that the hydrodynamic region is limited to smallq and small such that ||D |q|², whereD is the diffusion constant.     

The influence of graphite boat material on the purity of LPE InGaAs

This paper describes the purity of LPE InGaAs layers grown in graphite boats, machined from various graphite materials. The influence of the material is clearly visible if the growth solution is sufficiently pure. Carrier concentrations n<2×l0¹⁵ cm^–3 and mobilities(77 K)> 38000 cm²/Vs are routinely achieved for suitable graphite materials already from the third run of a new large boat applying a prebake of only 15 h. Small boats yield even better results (n=0.5×10¹⁵ cm^–3 and(77 K)=49500 m²/Vs). The sticking of In-rich solutions to the graphite does not depend on the material but is solely dependent on the surface roughness. The problem of graphite particle abrasion is discussed.     

Heat transfer analysis in the flow of Waiters＇ B fluid with a convective boundary condition

Radiative heat transfer in the steady two-dimensional flow of Walters＇ B fluid with a non-uniform heat source/sink is investigated. An incompressible fluid is bounded by a stretching porous surface. The convective boundary condition is used for the thermal boundary layer problem. The relevant equations are first simplified under usual boundary layer assumptions and then transformed into a similar form by suitable transformations. Explicit series solutions of velocity and temperature are derived by the homotopy analysis method （HAM）. The dimensionless velocity and temperature gradients at the wall are calculated and discussed.