Extremophiles and their application to veterinary medicine

<p/> <p>Extremophiles are organisms that can grow and thrive in harsh conditions, e.g., extremes of temperature, pH, salinity, radiation, pressure and oxygen tension. Thermophilic, halophilic and radiation-resistant organisms are all microbes, some of which are able to withstand multiple extremes. Psychrophiles, or cold-loving organisms, include not only microbes, but fish that live in polar waters and animals that can withstand freezing. Extremophiles are structurally adapted at a molecular level to withstand these conditions. Thermophiles have particularly stable proteins and cell membranes, psychrophiles have flexible cellular proteins and membranes and/or antifreeze proteins, salt-resistant halophiles contain compatible solutes or high concentrations of inorganic ions, and acidophiles and alkaliphiles are able to pump ions to keep their internal pH close to neutrality. Their interest to veterinary medicine resides in their capacity to be pathogenic, and as sources of enzymes and other molecules for diagnostic and pharmaceutical purposes. In particular, thermostable DNA polymerases are a mainstay of PCR-based diagnostics.</p

The stellar content of the isolated transition dwarf galaxy DDO210

We use Subaru Suprime-Cam and VLT FORS1 photometry of the dwarf galaxy DDO210 to study the global stellar content and structural properties of a transition-type galaxy (with properties intermediate between dwarf irregular and dwarf spheroidal systems). This galaxy is sufficiently isolated that tidal interactions are not likely to have affected its evolution in any way. The colour-magnitude diagrams of DDO210 show a red giant branch (RGB) population (with an RGB bump), a bright asymptotic giant branch population, a red clump, young main sequence stars and blue-loop stars. The youngest stars formed within the last 60 Myrs and have a distinct radial distribution compared to the main population. Whereas the overall stellar spatial distribution and HI spatial distribution are concentric, the young stars are offset from the center of DDO210 and are coincident with a `dent' in the HI distribution. The implied recent star formation rate required to form the young population is significantly higher than the derived current star formation rate, by a factor of > 10. Most of the stars in DDO210 are found in a red clump, and its mean I-band magnitude suggests that the majority of stars in DDO210 have an average age of 4^{+2}_{-1} Gyr. Given this age, the colour of the RGB implies a mean metallicity of [Fe/H] ~ -1.3. By comparing the shape of the red clump with models for a variety of star formation histories, we estimate that an old (> 10 Gyr) stellar population can contribute ~ 20 - 30% of the stars in DDO210 at most. The unusual star formation history of DDO210, its low mass estimate and its isolated nature, provide insight into how star formation proceeds in the lowest mass, unperturbed, dwarf galaxy haloes.Comment: 17 pages, 13 figures. Accepted by MNRA

Towards Enhanced Threat Intelligence Through NetFlow Distillation

Bolvedere is a hardware-accelerated NetFlow analysis platform intended to discern and distribute NetFlow records in a requested format by a user. This functionality removes the need for a user to deal with the NetFlow protocol directly, and also reduces the requirement of CPU resources as data would be passed on to a host in the known requested format

Towards malicious network activity mitigation through subnet reputation analysis

Analysis technologies that focus on partial packet rather than full packet analysis have shown promise in detection of malicious activity on net-works. NetFlow is one such emergent protocol that is used to log net-work flows through summarizing key features of them. These logs can then be exported to external NetFlow sinks and proper configuration can see effective bandwidth bottleneck mitigation occurring on net-works. Furthermore, each NetFlow source node is configurable with its own unique ID number. This feature enables a system that knows where a NetFlow source node ID number resides physically to say which network flows are occurring from which physical locations irre-spective of the IP addresses involved in these network flows

A Deep Photometric Look at Two of Andromeda's Dwarf Spheroidals: X and XVII

We use deep wide-field photometry from the Large Binocular Camera to study the stellar and structural properties of the recently discovered Andromeda X and Andromeda XVII (And X and And XVII) dwarf galaxies. Using the mean apparent magnitude of the horizontal branch (HB), we derive distances of 621 +- 20 kpc to And X and 734+- 23 kpc to And XVII, closer by >60 kpc than the previous estimates which were based on red giant branch (RGB) observations. Thus our results warrant against the use of the RGB tip method for determining distances to systems with sparsely populated RGBs, and show how crucial HB observations are in obtaining accurate distances in systems such as these. We find that And X is a relatively faint (MV = -7.36), highly elongated (e = 0.48) system at a distance of 174 +- 62 kpc from Andromeda. And XVII is brighter (MV = -8.61) with an M31-centric distance of 73 kpc which makes it one of the closest satellites to Andromeda. Both galaxies are metal-poor: we derive =-2.2 for And X, while And XVII shows = -2.0, consistent with the relation of higher luminosity dwarfs being more metal- rich. Additionally, both galaxies show considerable intrinsic spreads in metallicity (0.2 and 0.3 dex for And X and And XVII respectively), consistent with multiple stellar populations.Comment: 8 pages, 6 figure

The Tidal Evolution of Local Group Dwarf Spheroidals

(Abridged) We use N-body simulations to study the evolution of dwarf spheroidal galaxies (dSphs) driven by galactic tides. We adopt a cosmologically-motivated model where dSphs are approximated by a King model embedded within an NFW halo. We find that these NFW-embedded King models are extraordinarily resilient to tides; the stellar density profile still resembles a King model even after losing more than 99% of the stars. As tides strip the galaxy, the stellar luminosity, velocity dispersion, central surface brightness, and core radius decrease monotonically. Remarkably, we find that the evolution of these parameters is solely controlled by the total amount of mass lost from within the luminous radius. Of all parameters, the core radius is the least affected: after losing 99% of the stars, R_c decreases by just a factor of ~2. Interestingly, tides tend to make dSphs more dark-matter dominated because the tightly bound central dark matter ``cusp'' is more resilient to disruption than the ``cored'' King profile. We examine whether the extremely large M/L ratios of the newly-discovered ultra-faint dSphs might have been caused by tidal stripping of once brighter systems. Although dSph tidal evolutionary tracks parallel the observed scaling relations in the luminosity-radius plane, they predict too steep a change in velocity dispersion compared with the observational estimates hitherto reported in the literature. The ultra-faint dwarfs are thus unlikely to be the tidal remnants of systems like Fornax, Draco, or Sagittarius. Despite spanning four decades in luminosity, dSphs appear to inhabit halos of comparable peak circular velocity, lending support to scenarios that envision dwarf spheroidals as able to form only in halos above a certain mass threshold.Comment: 17 pages, 12 figs., accepted by Ap

The PAndAS view of the Andromeda satellite system - I. A Bayesian search for dwarf galaxies using spatial and color-magnitude information

We present a generic algorithm to search for dwarf galaxies in photometric catalogs and apply it to the Pan-Andromeda Archaeological Survey (PAndAS). The algorithm is developed in a Bayesian framework and, contrary to most dwarf-galaxy-search codes, makes use of both the spatial and color-magnitude information of sources in a probabilistic approach. Accounting for the significant contamination from the Milky Way foreground and from the structured stellar halo of the Andromeda galaxy, we recover all known dwarf galaxies in the PAndAS footprint with high significance, even for the least luminous ones. Some Andromeda globular clusters are also recovered and, in one case, discovered. We publish a list of the 143 most significant detections yielded by the algorithm. The combined properties of the 39 most significant isolated detections show hints that at least some of these trace genuine dwarf galaxies, too faint to be individually detected. Follow-up observations by the community are mandatory to establish which are real members of the Andromeda satellite system. The search technique presented here will be used in an upcoming contribution to determine the PAndAS completeness limits for dwarf galaxies. Although here tuned to the search of dwarf galaxies in the PAndAS data, the algorithm can easily be adapted to the search for any localised overdensity whose properties can be modeled reliably in the parameter space of any catalog.Comment: 20 pages, 16 figures, 1 table; accepted for publication in ApJ. High res pdf available at https://www.dropbox.com/s/7zk7pme2wunwkjv/PAndAS_dwarf_galaxies.pd

Improving Fidelity in Internet Simulation through Packet Injection

This paper describes the of extension implemented to the NKM Internet simulation system, which allows for the improved of injection of packet traffic at arbitrary nodes, and the replay of previously recorded streams. The latter function allows for the relatively easy implementation of Internet Background Radiation (IBR) within the simulated portion of the Internet. This feature thereby enhances the degree of realism of the simulation, and allows for certain pre-determined traffic, such as scanning activity, to be injected and observed by client systems connected to the simulator