65,956 research outputs found
On a Conjecture of Givental
These brief notes record our puzzles and findings surrounding Givental's
recent conjecture which expresses higher genus Gromov-Witten invariants in
terms of the genus-0 data. We limit our considerations to the case of a
projective line, whose Gromov-Witten invariants are well-known and easy to
compute. We make some simple checks supporting his conjecture.Comment: 13 pages, no figures; v.2: new title, minor change
Probing the Low Mass Stellar End of the eta Chamaeleontis Cluster
We have identified three faint new members of the eta Chamaeleontis cluster.
Spectral types of the new members are estimated to be ~M5 based on their TiO
band strengths and broadband colors. With an age of 5-8 Myr for the cluster,
masses of these new members are estimated to be ~0.08 Msun. All three display
strong Li 6708A absorption and Halpha emission features including one with
Halpha emission equivalent width ~60A along with HeI 6678 & 7605 A emission
features that are characteristics of classical T Tauri stars.Comment: 11 pages, 4 figures, 2 tables, accepted in Ap
A new calibration method for time delay standard and its application
A method which is used to measure time delay accurately by using a Type 900-LB slotted line is described. The accuracy for calibrating time delay of a precision coaxial air line Type 900-L is about + or - (0.4 to 0.6)ps, and for coaxial cables with VSWR less than 1.5 and time delay t less than 50ns is about + or - (3 to 5)ps. Theoretical analysis and mathematical derivation of microwave networks in cascade are given. Methods to eliminate the errors which are caused by the discontinuities and the error analysis of the measuring system are presented. Skin effect analysis of the transient characteristic of coaxial transmission line are discussed in detail. Methods to eliminate the errors which result from using the calibrated time delay standard to calibrate time interval measurement instruments are presented. The estimation of errors and formulae for correction of those errors are described
Bunching Transitions on Vicinal Surfaces and Quantum N-mers
We study vicinal crystal surfaces with the terrace-step-kink model on a
discrete lattice. Including both a short-ranged attractive interaction and a
long-ranged repulsive interaction arising from elastic forces, we discover a
series of phases in which steps coalesce into bunches of n steps each. The
value of n varies with temperature and the ratio of short to long range
interaction strengths. We propose that the bunch phases have been observed in
very recent experiments on Si surfaces. Within the context of a mapping of the
model to a system of bosons on a 1D lattice, the bunch phases appear as quantum
n-mers.Comment: 5 pages, RevTex; to appear in Phys. Rev. Let
Removal of mercury (II) from aqueous solution by using rice residues
Sorption potential of rice residues for Hg(II) removal from aqueous solution was investigated. Rice husk (RH) and rice straw (RS) were selected and treated with sodium hydroxide (NaOH). The raw and modified adsorbents were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and BET surface area measurements. The effects of pH, initial ion concentration, and agitation time on the removal process were studied in batch adsorption experiments. Two simple kinetic models, which are pseudo-first-order and pseudo-second-order, were tested to investigate the adsorption mechanisms. The kinetic data fits to pseudo second order model with correlation coefficients greater than 0.99 for all adsorbents. The equilibrium data fitted well with the Langmuir compared to Freundlich isotherm models. Alkali-treated adsorbent obtained larger surface area and RH-NaOH showed highest adsorption capacity followed by RS-Pure > RH-Pure > RS-NaOH. The maximum removal efficiency obtained by RH-NaOH and RS-Pure was 42 mg/l (80%) at pH 6.5 and with 2 days contact time (for 50 mg/l initial concentration and 25 mg adsorbents)
Coherent States and Geometric Phases in Calogero-Sutherland Model
Exact coherent states in the Calogero-Sutherland models (of time-dependent
parameters) which describe identical harmonic oscillators interacting through
inverse-square potentials are constructed, in terms of the classical solutions
of a harmonic oscillator. For quasi-periodic coherent states of the
time-periodic systems, geometric phases are evaluated. For the
Calogero-Sutherland model, the phase is calculated for a general coherent
state. The phases for other models are also considered.Comment: To appear in the Int. J. Mod. Phys.
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