We present the results of a dedicated effort to measure the spin-down rate of the nearby isolated neutron star RX J0720.4−3125. Comparing arrival times of the 8.39-sec pulsations for data from Chandra we derive an unambiguous timing solution for RX J0720.4−3125 that is accurate to < 0.1 cycles over > 5 years. Adding data from XMM and ROSAT, the final solution yields Ṗ = (6.98 ± 0.02) × 10 s s; ...

We report identification of a narrow-line Seyfert 1 galaxy RX J1236.9+2656. X-ray emission from the NLS1 galaxy undergoes long-term variability with 0.1– 2.0 keV flux changing by a factor of ∼ 2 within ∼ 3 yr. The ROSAT PSPC spectrum of RX J1236.9+2656 is well represented by a power-law of ΓX = 3.7 +0.5 −0.3 absorbed by matter in our own Galaxy (NH = 1.33 × 10 20 cm). Intrinsic soft X-ray lumin...

This paper describes a method for estimating the parameters of an autoregressive (AR) process from a nite number of noisy measurements. The method uses a modi ed set of YuleWalker equations that lead to a quadratic eigenvalue problem which when solved, gives estimates of the AR parameters and the measurement noise variance. Version 2, submitted to IEEE Transactions on Signal Processing January ...

We present a Hubble Space Telescope Advanced Camera for Surveys (ACS) weak-lensing study of RX J0849+4452 and RX J0848+4453, the two most distant (at z = 1.26 and z = 1.27, respectively) clusters yet measured with weak-lensing. The two clusters are separated by ∼ 4 from each other and appear to form a supercluster in the Lynx field. Using our deep ACS i775 and z850 imaging, we detected weak-len...

Very little theory is available to explain the reasons underlying ACO’s success. A population–based ACO (P-ACO) variant is used to explain the reasons of elitist ACO’s success in the TSP, given a globally convex structure of the solution space. 1 Reasons Underlying ACO’s Success For this work a TSP tour is denoted as rx, the optimal tour as r∗ and a population of m tours as P = {Pi}. Distance δ...

Many cryptographic primitives rely on word rotations (R) and xor (X) to provide proper mixing. We give RX-system mixing a very general treatment and deduce some theoretical results on related probability distributions. Pure RX-systems are easy to break, so we show how to apply our theory to a more complex system that uses RX operations in combination with S-boxes. We construct an impractical (k...

We present evidence from high resolution optical spectra for the presence of bipolar jets in the bright super soft X-ray source RX J0019.8+2156, the second such discovered case after RX J0513.9-6951. The jets seem to appear and disappear over a time scale of several months. No jet precession is observed. From the velocity separation of the emission lines produced by the jets a lower limit of ∼ ...

We assessed Escherichia coli ST131 and its H30 and H30-Rx subclones for virulence genes, antimicrobial resistance, and extended-spectrum beta-lactamase (ESBL) type. Although both subclones were associated with ESBL production, H30-Rx isolates had higher resistance scores and were associated specifically with CTX-M-15. Three virulence genes (iha, sat, and iutA) were more prevalent among H30 than...

Transmission over Multiple Input Multiple Output (MIMO) radio channels is considered. When multiple Rx antennas are present, one may simultaneously increase the rate and improve performance by optimizing transmit diversity, using nonorthogonal space-time block codes. This improves the performance of MIMO systems considerably, especially when the number of Tx and Rx antennas is small. As an exam...

Although high-resolution wide-swath (HRWS) SAR imaging and ground moving target indication (GMTI) systems from the system architecture point of view look quite similar (both system types employ multiple receiving (RX) channels arranged along azimuth direction), they generally need to be operated in different modes, in particular with significantly different PRFs. HRWS systems require a comparat...