Study of the scientific potential of a three 40 cm Telescopes Interferometer at Dome C

Recent site testing (see: http://www-luan.unice.fr/Concordiastro/indexantartic.html) has shown that Dome C in Antarctica might have a high potential for stellar interferometry if some solutions related to the surface atmospheric layer are found. A demonstrator interferometer could be envisioned in order to fully qualify the site and prepare the future development of a large array. We analyse the performances of a prototype interferometer for Dome C made with 3 telescopes of 40 cm diameter. It assumes classical Michelson recombination. The most recent atmospheric and environmental conditions measured at Dome C are considered (see K. Agabi "First whole atmosphere night-time seeing measurements at Dome C, Antarctica"). We also study the possible science reachable with such a demonstrator. Especially we evaluate that even such small aperture interferometer could allow the detection and low resolution spectroscopy of the most favourable pegaside planets.Comment: 6 pages, 5 figures, conferences SPIE, 0rlando, 200

Molecular dynamics simulations of iron- and aluminum-loaded serum transferrin: Protonation of tyr188 is necessary to prompt metal release

Serum transferrin (sTf) carries iron in blood serum and delivers it into cells by receptor-mediated endocytosis. The protein can also bind other metals, including aluminum. The crystal structures of the metal-free and metal-loaded protein indicate that the metal release process involves an opening of the protein. In this process, Lys206 and Lys296 lying in the proximity of each other form the dilysine pair or, so-called, dilysine trigger. It was suggested that the conformational change takes place due to variations of the protonation state of the dilysine trigger at the acidic endosomal pH. In 2003, Rinaldo and Field (Biophys. J. 85, 3485-3501) proposed that the dilysine trigger alone can not explain the opening and that the protonation of Tyr188 is required to prompt the conformational change. However, no evidence was supplied to support this hypothesis. Here, we present several 60 ns molecular dynamics simulations considering various protonation states to investigate the complexes formed by sTf with Fe(III) and Al(III). The calculations demonstrate that only in those systems where Tyr188 has been protonated does the protein undergo the conformational change and that the dilysine trigger alone does not lead to the opening. The simulations also indicate that the metal release process is a stepwise mechanism, where the hinge-bending motion is followed by the hinge-twisting step. Therefore, the study demonstrates for the first time that the protonation of Tyr188 is required for the release of metal from the metal loaded sTf and provides valuable information about the whole process

Exclusive Double Charmonium Production from Υ\Upsilon Decay

The exclusive decay of $\Upsilon$ to a vector plus pseudoscalar charmonium is studied in perturbative QCD. The corresponding branching ratios are predicted to be of order $10^{-6}$ for first three $\Upsilon$ resonances, and we expect these decay modes should be discovered in the prospective high-luminosity $e^+e^-$ facilities such as super $B$ experiment. As a manifestation of the short-distance loop contribution, the relative phases among strong, electromagnetic and radiative decay amplitudes can be deduced. It is particularly interesting to find that the relative phase between strong and electromagnetic amplitudes is nearly orthogonal. The resonance-continuum interference effect for double charmonium production near various $\Upsilon$ resonances in $e^+e^-$ annihilation is addressed

Fermionic Chern-Simons theory for the Fractional Quantum Hall Effect in Bilayers

We generalize the fermion Chern-Simons theory for the Fractional Hall Effect (FQHE) which we developed before, to the case of bilayer systems. We study the complete dynamic response of these systems and predict the experimentally accessible optical properties. In general, for the so called $(m, m, n)$ states, we find that the spectrum of collective excitations has a gap, and the wave function has the Jastrow-Slater form, with the exponents determined by the coefficients $m$, and $n$. We also find that the $(m,m,m)$ states, {\it i.~e.~}, those states whose filling fraction is $1\over m$, have a gapless mode which may be related with the spontaneous appearance of the interlayer coherence. Our results also indicate that the gapless mode makes a contribution to the wave function of the $(m,m,m)$ states analogous to the phonon contribution to the wave function of superfluid $\rm{He}_4$. We calculate the Hall conductance, and the charge and statistics of the quasiparticles. We also present an $SU(2)$ generalization of this theory relevant to spin unpolarized or partially polarized single layers.Comment: 55 pages, Urbana Prepin

From the Chern-Simons theory for the fractional quantum Hall effect to the Luttinger model of its edges

The chiral Luttinger model for the edges of the fractional quantum Hall effect is obtained as the low energy limit of the Chern-Simons theory for the two dimensional system. In particular we recover the Kac-Moody algebra for the creation and annihilation operators of the edge density waves and the bosonization formula for the electronic operator at the edge.Comment: 4 pages, LaTeX, 1 Postscript figure include

Electromagnetic characteristics and effective gauge theory of double-layer quantum Hall systems

The electromagnetic characteristics of double-layer quantum Hall systems are studied, with projection to the lowest Landau level taken into account and intra-Landau-level collective excitations treated in the single-mode approximation. It is pointed out that dipole-active excitations, both elementary and collective, govern the long-wavelength features of quantum Hall systems. In particular, the presence of the dipole-active interlayer out-of-phase collective excitations, inherent to double-layer systems, modifies the leading O(k) and O(k^{2}) long-wavelength characteristics (i.e., the transport properties and characteristic scale) of the double-layer quantum Hall states substantially. We apply bosonization techniques and construct from such electromagnetic characteristics an effective theory, which consists of three vector fields representing the three dipole-active modes, one interlayer collective mode and two inter-Landau-level cyclotron modes. This effective theory properly incorporates the spectrum of collective excitations on the right scale of the Coulomb energy and, in addition, accommodates the favorable transport properties of the standard Chern-Simons theories.Comment: 10 pages, Revtex, sec. II slightly shortened, to appear in Phys. Rev.

Infrared catastrophe and tunneling into strongly correlated electron systems: Perturbative x-ray edge limit

The tunneling density of states exhibits anomalies (cusps, algebraic suppressions, and pseudogaps) at the Fermi energy in a wide variety of low-dimensional and strongly correlated electron systems. We argue that in many cases these spectral anomalies are caused by an infrared catastrophe in the screening response to the sudden introduction of a new electron into the system during a tunneling event. A nonperturbative functional-integral method is introduced to account for this effect, making use of methods developed for the x-ray edge singularity problem. The formalism is applicable to lattice or continuum models of any dimensionality, with or without translational invariance. An approximate version of the technique is applied to the 1D electron gas and the 2D Hall fluid, yielding qualitatively correct results.Comment: 6 page

Non-equilibrium tunneling into general quantum Hall edge states

In this paper we formulate the theory of tunneling into general Abelian fractional quantum Hall edge states. In contrast to the simple Laughlin states, a number of charge transfer processes must be accounted for. Nonetheless, it is possible to identify a unique value corresponding to dissipationless transport as the asymptotic large-$V$ conductance through a tunneling junction, and find fixed points (CFT boundary conditions) corresponding to this value. The symmetries of a given edge tunneling problem determine the appropriate boundary condition, and the boundary condition determines the strong-coupling operator content and current noise.Comment: 6 pages, 3 figures; published versio

Composite fermion theory of collective excitations in fractional quantum Hall effect

The low energy neutral excitations of incompressible fractional quantum Hall states are called collective modes or magnetic excitons. This work develops techniques for computing their dispersion at general filling fractions for reasonably large systems. New structure is revealed; in particular, the collective mode at 1/3 is found to possess several minima, with the energy of the principal minimum significantly smaller than the earlier estimate. \pacs{73.40.Hm, 73.20.Dx, 73.20.Mf}Comment: 4 pages, 3 postscript figure

Neutrino-Mixing-Generated Lepton Asymmetry and the Primordial 4^4He Abundance

It has been proposed that an asymmetry in the electron neutrino sector may be generated by resonant active-sterile neutrino transformations during Big Bang Nucleosynthesis (BBN). We calculate the change in the primordial $^4$He yield $Y$ resulting from this asymmetry, taking into account both the time evolution of the $\nu_e$ and $\bar\nu_e$ distribution function and the spectral distortions in these. We calculate this change in two schemes: (1) a lepton asymmetry directly generated by $\nu_e$ mixing with a lighter right-handed sterile neutrino $\nu_s$; and (2) a lepton asymmetry generated by a $\nu_\tau\leftrightarrow\nu_s$ or $\nu_\mu\leftrightarrow\nu_s$ transformation which is subsequently partially converted to an asymmetry in the $\nu_e\bar\nu_e$ sector by a matter-enhanced active-active neutrino transformation. In the first scheme, we find that the percentage change in $Y$ is between -1% and 9% (with the sign depending on the sign of the asymmetry), bounded by the Majorana mass limit m_{\nu_e}\la 1 eV. In the second scheme, the maximal percentage reduction in $Y$ is 2%, if the lepton number asymmetry in neutrinos is positive; Otherwise, the percentage increase in $Y$ is \la 5% for m^2_{\nu_\mu,\nu_\tau}-m^2_{\nu_s}\la 10^4 eV. We conclude that the change in the primordial $^4$He yield induced by a neutrino-mixing-generated lepton number asymmetry can be substantial in the upward direction, but limited in the downward direction.Comment: 15 pages, 7 figures, submitted to PR