Growth curves for algebras

This paper studies matrix representations of algebras (over a field) using countably-infinite matrices which are both row and column finite, and in which the bandwidth growth is controlled. The ideas lead naturally to a concept of "growth of an algebra", somewhat analogous to the growth associated with GK-dimension. They also lead in a similar way to a dimension function on general algebras, which we term bandwidth dimension. For each real number r ∈ [0,1], we construct an algebra having bandwidth dimension precisely r. Since the free algebra turns out to have bandwidth dimension 0, our new dimension promises to distinguish among algebras of infinite GK-dimension

Effects of pathogen priming on judgements of face and voice attractiveness and health [oral presentation]

It has been shown (e.g. Wells et al., 2011) that whilst individuals can use both face and voice quality to make judgements of perceived attractiveness and health, in face-voice compounds, face quality typically overshadows (dominates) the judgement. It has also been shown that priming about environmental pathogen load can have a significant effect on a range judgements and behaviours (e.g. Dunn & Chambers, 2011; Little et al., 2011). Here we report on two experiments (Exp. 1 & Exp. 2), in which we explored the effects of implicit pathogen priming on face/voice attractiveness ratings (Exp. 1) and voice health ratings (Exp. 2). In Exp. 1 we show that although average attractiveness ratings for component (face or voice) and compound (face-voice) targets do not significantly change, following priming, the amount of variance accounted for by the component voice ratings in relation to the compound face-voice ratings, significantly increased, thereby removing face overshadowing. In Exp. 2 we show that whilst priming significantly shifts voice health judgements, relative to baseline, there is also a significant difference between priming the past environment (time of target stimulus collection) or the present environment (time of rating). The difference was such that priming the past produced a significantly smaller shift in voice ratings than priming the present. The findings from both experiments demonstrate that personal preference changes when pathogen load is perceived to be high, and that temporal information mediates this influence. These findings are consistent with a behavioural immune system hypothesis (e.g. Schaller & Duncan 2007)

Illustrating the Geometry of Coherently Controlled Quantum Channels

We extend standard Markovian open quantum systems (quantum channels) by allowing for Hamiltonian controls and elucidate their geometry in terms of Lie semigroups. For standard dissipative interactions with the environment and different coherent controls, we particularly specify the tangent cones (Lie wedges) of the respective Lie semigroups of quantum channels. These cones are the counterpart of the infinitesimal generator of a single one-parameter semigroup. They comprise all directions the underlying open quantum system can be steered to and thus give insight into the geometry of controlled open quantum dynamics. Such a differential characterisation is highly valuable for approximating reachable sets of given initial quantum states in a plethora of experimental implementations.Comment: condensed and updated version; 14 pages; comments welcom

The First Data Release of the KODIAQ Survey

We present and make publicly available the first data release (DR1) of the Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ) survey. The KODIAQ survey is aimed at studying galactic and circumgalactic gas in absorption at high-redshift, with a focus on highly-ionized gas traced by OVI, using the HIRES spectrograph on the Keck-I telescope. KODIAQ DR1 consists of a fully-reduced sample of 170 quasars at 0.29 < z_em < 5.29 observed with HIRES at high resolution (36,000 <= R <= 103,000) between 2004 and 2012. DR1 contains 247 spectra available in continuum normalized form, representing a sum total exposure time of ~1.6 megaseconds. These co-added spectra arise from a total of 567 individual exposures of quasars taken from the Keck Observatory Archive (KOA) in raw form and uniformly processed using a HIRES data reduction package made available through the XIDL distribution. DR1 is publicly available to the community, housed as a higher level science product at the KOA. We will provide future data releases that make further QSOs, including those with pre-2004 observations taken with the previous-generation HIRES detectors.Comment: 14 pages, 9 figures, Submitted to AJ. All data products available at the Keck Observatory Archive beginning May 15, 2015. URL: https://koa.ipac.caltech.edu/applications/KODIA

A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic Medium

Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C IV absorption systems and the properties of nearby galaxies as well as large-scale environment. To maintain sensitivity to very faint galaxies, we restrict our sample to 0.0015 < z < 0.015, which defines a complete galaxy survey to L > 0.01 L* or stellar mass log M_* > 8 Msun. We report two principal findings. First, for galaxies with impact parameter rho < 1 rvir, C IV detection strongly depends on the luminosity/stellar mass of the nearby galaxy. C IV is preferentially associated with galaxies with log M_* > 9.5 Msun; lower mass galaxies rarely exhibit significant C IV absorption (covering fraction f = 9 +12-6% for 11 galaxies with log M_* < 9.5 Msun). Second, C IV detection within the log M_* > 9.5 Msun population depends on environment. Using a fixed-aperture environmental density metric for galaxies with rho < 160 kpc at z < 0.055, we find that 57+/-12% (8/14) of galaxies in low-density regions (regions with fewer than seven L > 0.15 L* galaxies within 1.5 Mpc) have affiliated C IV absorption; however, none (0/7) of the galaxies in denser regions show C IV. Similarly, the C IV detection rate is lower for galaxies residing in groups with dark-matter halo masses of log Mhalo > 12.5 Msun. In contrast to C IV, H I is pervasive in the CGM without regard to mass or environment. These results indicate that C IV absorbers with log N(C IV) > 13.5 cm^-2 trace the halos of log M_* > 9.5 Msun galaxies but also reflect larger scale environmental conditions.Comment: 26 pages, 13 figures. ApJ, in pres