Heating and Turbulence Driving by Galaxy Motions in Galaxy Clusters

Using three-dimensional hydrodynamic simulations, we investigate heating and turbulence driving in an intracluster medium (ICM) by orbital motions of galaxies in a galaxy cluster. We consider Ng member galaxies on isothermal and isotropic orbits through an ICM typical of rich clusters. An introduction of the galaxies immediately produces gravitational wakes, providing perturbations that can potentially grow via resonant interaction with the background gas. When Ng^{1/2}Mg_11 < 100, where Mg_11 is each galaxy mass in units of 10^{11} Msun, the perturbations are in the linear regime and the resonant excitation of gravity waves is efficient to generate kinetic energy in the ICM, resulting in the velocity dispersion sigma_v ~ 2.2 Ng^{1/2}Mg_11 km/s. When Ng^{1/2}Mg_11 > 100, on the other hand, nonlinear fluctuations of the background ICM destroy galaxy wakes and thus render resonant excitation weak or absent. In this case, the kinetic energy saturates at the level corresponding to sigma_v ~ 220 km/s. The angle-averaged velocity power spectra of turbulence driven in our models have slopes in the range of -3.7 to -4.3. With the nonlinear saturation of resonant excitation, none of the cooling models considered are able to halt cooling catastrophe, suggesting that the galaxy motions alone are unlikely to solve the cooling flow problem.Comment: 12 pages including 3 figures, To appear in ApJ

Characterizing the radial oxygen abundance distribution in disk galaxies

We examine the possible dependence of the radial oxygen abundance distribution on non-axisymmetrical structures (bar/spirals) and other macroscopic parameters such as the mass, the optical radius R25, the color g-r, and the surface brightness of the galaxy. A sample of disk galaxies from the CALIFA DR3 is considered. We adopted the Fourier amplitude A2 of the surface brightness as a quantitative characteristic of the strength of non-axisymmetric structures in a galactic disk, in addition to the commonly used morphologic division for A, AB, and B types based on the Hubble classification. To distinguish changes in local oxygen abundance caused by the non-axisymmetrical structures, the multiparametric mass--metallicity relation was constructed as a function of parameters such as the bar/spiral pattern strength, the disk size, color index g-r in the SDSS bands, and central surface brightness of the disk. The gas-phase oxygen abundance gradient is determined by using the R calibration. We find that there is no significant impact of the non-axisymmetric structures such as a bar and/or spiral patterns on the local oxygen abundance and radial oxygen abundance gradient of disk galaxies. Galaxies with higher mass, however, exhibit flatter oxygen abundance gradients in units of dex/kpc, but this effect is significantly less prominent for the oxygen abundance gradients in units of dex/R25 and almost disappears when the inner parts are avoided. We show that the oxygen abundance in the central part of the galaxy depends neither on the optical radius R25 nor on the color g-r or the surface brightness of the galaxy. Instead, outside the central part of the galaxy, the oxygen abundance increases with g-r value and central surface brightness of the disk.Comment: 11 pages, 6 figures; accepted for publication in A&

Towards predicting post-editing productivity

Machine translation (MT) quality is generally measured via automatic metrics, producing scores that have no meaning for translators who are required to post-edit MT output or for project managers who have to plan and budget for transla- tion projects. This paper investigates correlations between two such automatic metrics (general text matcher and translation edit rate) and post-editing productivity. For the purposes of this paper, productivity is measured via processing speed and cognitive measures of effort using eye tracking as a tool. Processing speed, average fixation time and count are found to correlate well with the scores for groups of segments. Segments with high GTM and TER scores require substantially less time and cognitive effort than medium or low-scoring segments. Future research involving score thresholds and confidence estimation is suggested

Time-delayed feedback control in astrodynamics

In this paper we present time-delayed feedback control (TDFC) for the purpose of autonomously driving trajectories of nonlinear systems into periodic orbits. As the generation of periodic orbits is a major component of many problems in astodynamics we propose this method as a useful tool in such applications. To motivate the use of this method we apply it to a number of well known problems in the astrodynamics literature. Firstly, TDFC is applied to control in the chaotic attitude motion of an asymmetric satellite in an elliptical orbit. Secondly, we apply TDFC to the problem of maintaining a spacecraft in a periodic orbit about a body with large ellipticity (such as an asteroid) and finally, we apply TDFC to eliminate the drift between two satellites in low Earth orbits to ensure their relative motion is bounded

Non-market Valuation Biases Due to Aboriginal Cultural Characteristics in Northern Saskatchewan: The Values Structures Component

Current non-market valuation techniques have been developed based on assumptions about values held within the Eurocentred culture. Contentions between cultures over natural resources are hypothesized to occur because of differences in held values resulting in different values being assigned to the resources in question. This study measured the held values of an Aboriginal band in Northern Saskatchewan as the first dimension of a non-market valuation study of natural resources. These held value structures are presented noting differences by age and gender and in comparison with the local Non-Aboriginal community and another Aboriginal group in northern Alberta.Resource /Energy Economics and Policy,

A Neurosemantic Theory of Concrete Noun Representation Based on the Underlying Brain Codes

This article describes the discovery of a set of biologically-driven semantic dimensions underlying the neural representation of concrete nouns, and then demonstrates how a resulting theory of noun representation can be used to identify simple thoughts through their fMRI patterns. We use factor analysis of fMRI brain imaging data to reveal the biological representation of individual concrete nouns like apple, in the absence of any pictorial stimuli. From this analysis emerge three main semantic factors underpinning the neural representation of nouns naming physical objects, which we label manipulation, shelter, and eating. Each factor is neurally represented in 3–4 different brain locations that correspond to a cortical network that co-activates in non-linguistic tasks, such as tool use pantomime for the manipulation factor. Several converging methods, such as the use of behavioral ratings of word meaning and text corpus characteristics, provide independent evidence of the centrality of these factors to the representations. The factors are then used with machine learning classifier techniques to show that the fMRI-measured brain representation of an individual concrete noun like apple can be identified with good accuracy from among 60 candidate words, using only the fMRI activity in the 16 locations associated with these factors. To further demonstrate the generativity of the proposed account, a theory-based model is developed to predict the brain activation patterns for words to which the algorithm has not been previously exposed. The methods, findings, and theory constitute a new approach of using brain activity for understanding how object concepts are represented in the mind

Effect of Human Exogenous Leukocyte Interferon in Cytomegalovirus Infections

Human leukocyte interferon was injected into nine patients with cytomegalovirus infections; four of these patients were congenitally infected, and five had acquired infections. In three patients viruria was completely inhibited. In five patients viral excretion in the urine was only transiently inhibited. Viremia was not significantly suppressed. The lymphocyte response to phytohemagglutinin was suppressed in two patient

Designing Interactive Secure Systems: CHI 2013 Special Interest Group

Despite a growing interest in the design and engineering of interactive secure systems, there is also a noticeable amount of fragmentation. This has led to a lack of awareness about what research is currently being carried out, and misunderstandings about how different fields can contribute to the design of usable and secure systems. By drawing interested members of the CHI community from design, user experience, engineering, and HCI Security, this SIG will take the first steps towards creating a research agenda for interactive secure system design. In the SIG, we will summarise recent initiatives to develop a research programme in interactive secure system design, network members of the CHI community with an interest in this research area, and initiate a roadmap towards addressing identified research challenges and building an interactive secure system design community