Feature Engineering for Detection of Wormhole Attacking in Mobile Ad Hoc Networks with Machine Learning Methods

Due to the self-configuring nature of a Mobile Ad Hoc Network (MANET), each node must participate in the routing process, in addition to its other activities. Therefore, routing in a MANET is especially vulnerable to malicious node activity leading to potentially severe disruption in network communications. The wormhole attack is a particularly severe MANET routing threat since it is easy to launch, can be launched in several modes, difficult to detect, and can cause significant communication disruption. In this paper we establish a practice for feature engineering of network data for wormhole attack prevention and detection with intrusion detection methods based on machine learning

A Rich Population of X-ray Emitting Wolf-Rayet Stars in the Galactic Starburst Cluster Westerlund 1

Recent optical and IR studies have revealed that the heavily-reddened starburst cluster Westerlund 1 (Wd 1) contains at least 22 Wolf-Rayet (WR) stars, comprising the richest WR population of any galactic cluster. We present results of a senstive Chandra X-ray observation of Wd 1 which detected 12 of the 22 known WR stars and the mysterious emission line star W9. The fraction of detected WN stars is nearly identical to that of WC stars. The WN stars WR-A and WR-B as well as W9 are exceptionally luminous in X-rays and have similar hard heavily-absorbed spectra with strong Si XIII and S XV emission lines. The luminous high-temperature X-ray emission of these three stars is characteristic of colliding wind binary systems but their binary status remains to be determined. Spectral fits of the X-ray bright sources WR-A and W9 with isothermal plane-parallel shock models require high absorption column densities log N$_{H}$ = 22.56 (cm$^{-2}$) and yield characteristic shock temperatures kT_shock ~ 3 keV (T ~ 35 MK).Comment: ApJL, 2006, in press (3 figures, 1 table

A hidden population of Wolf-Rayet stars in the massive galactic cluster Westerlund 1

We report the discovery of a hitherto undetected population of Wolf-Rayet stars in the young galactic open cluster Westerlund 1. Optical spectroscopy of the cluster identified 11 such objects; provisional classification suggests that 6 are nitrogen rich (WN) and 5 carbon rich (WC). Including the previously identified Blue, Yellow and Red Super- & Hypergiants, Westerlund 1 clearly has a very rich population of massive post-Main Sequence objects. To date, the post-MS population of Westerlund 1 is significantly larger than that of any other galactic young open cluster - with the possible exception of the Arches - implying that it is potentially amongst the most massive young clusters yet identified in the Local Group.Comment: 3 figures; uses new A&A style (included) Letter accepted for publication in Astronomy & Astrophysic

A newly identified Luminous Blue Variable in the galactic starburst cluster Westerlund 1

We present observations of the massive transitional star W243 in Westerlund 1 . We find an apparent spectral type of early-mid A from our data, in contrast to an earlier classification of B2I, made from data obtained in 1981. The concurrent development of a rich emission line spectrum suggests a very high mass loss rate; the continued presence of He I emission suggesting that the underlying star remains significantly hotter than implied by its apparent spectral type. We suggest that W243 is a Luminous Blue Variable undergoing an eruptive phase, leading to an extreme mass loss rate and the formation of a pseudo photosphere

Assessing The Accuracy Of Radio Astronomy Source Finding Algorithms

This work presents a method for determining the accuracy of a source finder algorithm for spectral line radio astronomy data and the Source Finder Accuracy Evaluator (SFAE), a program that implements this method. The accuracy of a source finder is defined in terms of its completeness, reliability, and accuracy of the parameterisation of the sources that were found. These values are calculated by executing the source finder on an image with a known source catalogue, then comparing the output of the source finder to the known catalogue. The intended uses of SFAE include determining the most accurate source finders for use in a survey, determining the types of radio sources a particular source finder is capable of accurately locating, and identifying optimum parameters and areas of improvement for these algorithms. This paper demonstrates a sample of accuracy information that can be obtained through this method, using a simulated ASKAP data cube and the Duchamp source finder.Comment: 8 pages, 6 figures, to be published in Publications of the Astronomical Society of Australi

NGC 602 Environment, Kinematics and Origins

The young star cluster NGC 602 and its associated HII region, N90, formed in a relatively isolated and diffuse environment in the Wing of the Small Magellanic Cloud. Its isolation from other regions of massive star formation and the relatively simple surrounding HI shell structure allows us to constrain the processes that may have led to its formation and to study conditions leading to massive star formation. We use images from Hubble Space Telescope and high resolution echelle spectrographic data from the Anglo-Australian Telescope along with 21-cm neutral hydrogen (HI) spectrum survey data and the shell catalogue derived from it to establish a likely evolutionary scenario leading to the formation of NGC 602. We identify a distinct HI cloud component that is likely the progenitor cloud of the cluster and HII region which probably formed in blister fashion from the cloud's periphery. We also find that the past interaction of HI shells can explain the current location and radial velocity of the nebula. The surrounding Interstellar Medium is diffuse and dust-poor as demonstrated by a low visual optical depth throughout the nebula and an average HI density of the progenitor cloud estimated at 1 cm^-3. These conditions suggest that the NGC 602 star formation event was produced by compression and turbulence associated with HI shell interactions. It therefore represents a single star forming event in a low gas density region.Comment: Accepted for publication in PASP. 25 pages, 10 figure

Further Wolf-Rayet stars in the starburst cluster Westerlund 1

We present new low and intermediate-resolution spectroscopic observations of the Wolf Rayet (WR) star population in the massive starburst cluster Westerlund 1. Finding charts are presented for five new WRs - four WNL and one WCL - raising the current total of known WRs in the cluster to 19. We also present new spectra and correct identifications for the majority of the 14 WR stars previously known, notably confirming the presence of two WNVL stars. Finally we briefly discuss the massive star population of Westerlund 1 in comparison to other massive young galactic clusters.Comment: Accepted for publication in Astronomy & Astrophysics. Eight pages, six figures. Replaced with final version, some minor change

Robust block bootstrap panel predictability tests

Most panel data studies of the predictability of returns presume that the cross-sectional units are independent, an assumption that is not realistic. As a response to this, the current paper develops block bootstrap-based panel predictability tests that are valid under very general conditions. Some of the allowable features include heterogeneous predictive slopes, persistent predictors, and complex error dynamics, including cross-unit endogeneity

Combination of Cold Atmospheric Plasma and Vitamin C Effectively Disrupts Bacterial Biofilms

Cold atmospheric plasma (CAP) is increasingly used in medical applications for eradication of bacterial and tumorcells. CAP treatment devices, known as plasma jet pens, produce reactive oxygen and nitrogen species atatmospheric pressure and room temperature. The produced reactive species are concentrated in a small andprecisely defined area, allowing for high precision medical treatments. CAP has been demonstrated as very effectiveagainst planktonic bacterial cells. Unfortunately, bacterial cells in biofilms are typically aggregated and protected bydense exopolymeric matrix, synthesized and secreted by the bacterial community. The main limitation in using CAPagainst bacterial biofilms is the thick protective matrix of extracellular polymers that shields bacterial cells within thiscomplex architecture. CAP has also been shown to effectively eradicate tumor cells, but the main current limitation isthe susceptibility of the surrounding healthy tissues to higher doses. We have recently demonstrated that vitamin C,a natural food supplement, can be used to destabilize bacterial biofilms and render them more susceptible to theCAP killing treatment. Here we discuss the possible impact that a pre-treatment with vitamin C could have on CAPapplications in medicine. Specifically, we argue that vitamin C could enhance the effectiveness of CAP treatmentsagainst both the bacterial biofilms and some selected tumors

The Nature of the Density Clump in the Fornax Dwarf Spheroidal Galaxy

We have imaged the recently discovered stellar overdensity located approximately one core radius from the center of the Fornax dwarf spheroidal galaxy using the Magellan Clay 6.5m telescope with the Magellan Instant Camera (MagIC). Superb seeing conditions allowed us to probe the stellar populations of this overdensity and of a control field within Fornax to a limiting magnitude of R=26. The color-magnitude diagram of the overdensity field is virtually identical to that of the control field with the exception of the presence of a population arising from a very short (less than 300 Myr in duration) burst of star formation 1.4 Gyr ago. Coleman et al. have argued that this overdensity might be related to a shell structure in Fornax that was created when Fornax captured a smaller galaxy. Our results are consistent with this model, but we argue that the metallicity of this young component favors a scenario in which the gas was part of Fornax itself.Comment: 24 pages including 8 figures and 3 tables. Accepted by Astronomical Journa