Optimal Alphabetic Ternary Trees

We give a new algorithm to construct optimal alphabetic ternary trees, where every internal node has at most three children. This algorithm generalizes the classic Hu-Tucker algorithm, though the overall computational complexity has yet to be determined

Model-independent constraints on reionization from large-scale CMB polarization

On large angular scales, the polarization of the CMB contains information about the evolution of the average ionization during the epoch of reionization. Interpretation of the polarization spectrum usually requires the assumption of a fixed functional form for the evolution, e.g. instantaneous reionization. We develop a model-independent method where a small set of principal components completely encapsulate the effects of reionization on the large-angle E-mode polarization for any reionization history within an adjustable range in redshift. Using Markov Chain Monte Carlo methods, we apply this approach to both the 3-year WMAP data and simulated future data. WMAP data constrain two principal components of the reionization history, approximately corresponding to the total optical depth and the difference between the contributions to the optical depth at high and low redshifts. The optical depth is consistent with the constraint found in previous analyses of WMAP data that assume instantaneous reionization, with only slightly larger uncertainty due to the expanded set of models. Using the principal component approach, WMAP data also place a 95% CL upper limit of 0.08 on the contribution to the optical depth from redshifts z>20. With improvements in polarization sensitivity and foreground modeling, approximately five of the principal components can ultimately be measured. Constraints on the principal components, which probe the entire reionization history, can test models of reionization, provide model-independent constraints on the optical depth, and detect signatures of high-redshift reionization.Comment: 14 pages, 13 figures; submitted to Ap

Green's function method for single-particle resonant states in relativistic mean field theory

Relativistic mean field theory is formulated with the Green's function method in coordinate space to investigate the single-particle bound states and resonant states on the same footing. Taking the density of states for free particle as a reference, the energies and widths of single-particle resonant states are extracted from the density of states without any ambiguity. As an example, the energies and widths for single-neutron resonant states in $^{120}$Sn are compared with those obtained by the scattering phase-shift method, the analytic continuation in the coupling constant approach, the real stabilization method and the complex scaling method. Excellent agreements are found for the energies and widths of single-neutron resonant states.Comment: 20 pages, 7 figure

Effect and Compensation of Timing Jitter in Through-Wall Human Indication via Impulse Through-Wall Radar

Impulse through-wall radar (TWR) is considered as one of preferred choices for through-wall human indication due to its good penetration and high range resolution. Large bandwidth available for impulse TWR results in high range resolution, but also brings an atypical adversity issue not substantial in narrowband radars — high timing jitter effect, caused by the non-ideal sampling clock at the receiver. The fact that impulse TWR employs very narrow pulses makes little jitter inaccuracy large enough to destroy the signal correlation property and then degrade clutter suppression performance. In this paper, we focus on the timing jitter impact on clutter suppression in through-wall human indication via impulse TWR. We setup a simple timing jitter model and propose a criterion namely average range profile (ARP) contrast is to evaluate the jitter level. To combat timing jitter, we also develop an effective compensation method based on local ARP contrast maximization. The proposed method can be implemented pulse by pulse followed by exponential average background subtraction algorithm to mitigate clutters. Through-wall experiments demonstrate that the proposed method can dramatically improve through-wall human indication performance

Solar cycle variation of real CME latitudes

With the assumption of radial motion and uniform longitudinal distribution of coronal mass ejections (CMEs), we propose a method to eliminate projection effects from the apparent observed CME latitude distribution. This method has been applied to SOHO LASCO data from 1996 January to 2006 December. As a result, we find that the real CME latitude distribution had the following characteristics: (1) High-latitude CMEs ($\theta>60^{\circ}$ where $\theta$ is the latitude) constituted 3% of all CMEs and mainly occurred during the time when the polar magnetic fields reversed sign. The latitudinal drift of the high-latitude CMEs was correlated with that of the heliospheric current sheet. (2) 4% of all CMEs occurred in the range $45^{\circ}\leq\theta\leq60^{\circ}$. These mid-latitude CMEs occurred primarily in 2000, near the middle of 2002 and in 2005, respectively, forming a prominent three-peak structure; (3) The highest occurrence probability of low-latitude ($\theta< 45^{\circ}$) CMEs was at the minimum and during the declining phase of the solar cycle. However, the highest occurrence rate of low-latitude CMEs was at the maximum and during the declining phase of the solar cycle. The latitudinal evolution of low-latitude CMEs did not follow the Sp\"{o}rer sunspot law, which suggests that many CMEs originated outside of active regions.Comment: 4 pages, 4 figures, accepted by ApJ Lette

On the Three-dimensional Lattice Model

Using the restricted star-triangle relation, it is shown that the $N$-state spin integrable model on a three-dimensional lattice with spins interacting round each elementary cube of the lattice proposed by Mangazeev, Sergeev and Stroganov is a particular case of the Bazhanov-Baxter model.Comment: 8 pages, latex, 4 figure