Systematic studies in Australian platystomatidae (Diptera)

Imperial Users onl

Hospitality in necessitudine : hospices, hostels and hospitals

In the continuing series reflecting on hospitality Mario Conti, Kevin O'Gorman and David McAlpine explore an aspect of hospitality often overlooked - the constantly evolving religious practice of providing hospitality to those in most need. They present an overview of the evolution of hospitality for the needy and consider how throughout history, even when religion is under attack, there has always been recognition of the importance of charitable hospitality: hospitality in necessitudine

Relationships of the Megamerinidae (Diptera: Nerioidea).

Den rezenten Megamerinidae werden lediglich die Gattungen Megamerina Rondani und Texara Walker zugeordnet. Nach einem weitergefaßten Konzept (sensu Hendel) ist die Familie durch 7 Apomorphien charakterisiert. Es wird jedoch gezeigt, daß diese von geringer phylogenetischer Bedeutung sind, da sie sich fast allesamt und in derselben Kombination konvergent in 10 verschiedenen Taxa der Schizophora herausbildeten, die von Hendel nicht den Megamerinidae zugeordnet wurden. Obwohl die Megamerinidae oft zu den Diopsoidea (subjektives Synonym: Nothyboidea) gestellt werden, weisen morphologische Merkmale auf eine nähere Verwandtschaft zu den Nerioidea hin. Die Verwandtschaftsbeziehungen fossiler und rezenter Gattungen werden untersucht.The recent Megamerinidae are here restricted to the genera Megamerina Rondani and Texara Walker. A more inclusive concept of the Megamerinidae (sensu Hendel) is characterised by a set of 7 apomorphic character states. This set is shown to have been separately derived almost in its entirety as a convergent cluster in 10 different schizophoran taxa, other than those included by Hendel. The set therefore has little phylogenetic significance. Though the Megamerinidae are often placed in the superfamily Diopsoidea (subjective syn. Nothyboidea), morphological evidence is presented to indicate a closer relationship to the Nerioidea. The relationships of the fossil and Recent genera are considered

Model of Hot-Film Sensor with Substrate Effects

A detailed mathematical model is constructed to investigate the frequency response of a hot-film anemometer system. Since several diverse factors affect the frequency response, the analysis is broken down into three main parts. Each part is a detailed mathematical model. The first model consists of the ordinary differential equations which govern the electronics of the feedback system and heat transfer of the sensor. An important simplification in this model is that the rate of heat conduction from the sensor to its substrate is constant. In the second model the unsteady state heat transfer properties of the substrate are examined by numerically solving the appropriate partial differential equation. A two pole equivalent circuit is constructed from the results of the second model. A third model results from merging the first part with the equivalent circuit. In this model the rate of heat conduction from sensor to substrate is not assumed to be constant

T cell activation in Theileria annulata infection: implications for immunity and pathogenesis

Theileria annulata is a protozoan parasite of cattle, causing the lymphoproliferative disease tropica] theileriosis. Ir susceptible animals, disease progresses rapidly, with the host apparently unable to mount an effective immune response. The parasite infects MHC class II+ monocytes and macrophages, during its pathogenic macroschizont stage. This leads to an augmentation of their antigen presenting capability in vitro - infected cells (IC) can induce proliferation of autologous resting T cells from naive animals. Preliminary studies showed that such altered APC function was a barrier to isolating Theileria specific T cells from immune animals. Infection of APC leading to a change in their function may provide T.annulata with a mechanism to evade the host immune response. This thesis sets out to understand interactions between T cells and T. annulata infected cells, both in vitro and in vivo and the consequences for the generation of immunity.In vitro stimulation of peripheral blood T cells from naive animals by IC caused the cells to proliferate, peaking 5 days post stimulation. Phenotypic analysis showed that CD25 and MHC class II were expressed upon the surface of all T cells (CD4.CD8 and 76T cells) within 24hrs of stimulation, reaching a peak at 48hrs and remaining stably expressed for up to 7 days post activation. The parasite infected cells could activate both "memory" and "naive" CD4 T cells, with little change in the CD45RB isoforms during activation. Activation of T cells was contact dependant. T.annulata infected cells can therefore cause the activation of the majority of T cells from naive animals irrespective of memory status and, presumably, antigen specificity.vation of the majority of T cells from naive animals irrespective of memory status and, presumably, antigen specificity. The cytokines produced by IC stimulated T cells 1-7 days post stimulation were assessed by reverse transcription polymerase chain reaction (RT-PCR) using primers for IL2, IL2 receptor (IL2R), IL4 and interferon gamma (IFNy). None of these cytokines were found to be expressed by 1C. T cells within PBM expressed mRNA for IL2, IL2R, IL4 and IFNy 24-48 hours post IC stimulation. IL2 and its receptor were still expressed at day 5 (peak proliferation), and waned by day 7. IFNy was expressed by all tested animals' cells at all timepoints, while IL4 was intermittently found at day 5 and was always absent at day 7. IL4 was only expressed by CD4 T cells, while lL2/IL2R/IFNy was expressed by all T cell types. The presence of CD4 cells was required for 1L2 and IL2R expression by non CD4 T cells.In vivo examination was of the draining lymph node (DLN) which is the principal site of parasite development, ideally placing the parasite to interfere with the induction of immunity. DLN exhibited radically altered distributions of T cells expressing activation markers from accepted steps in immune response development. Infected cells were first manifested as proliferating non T non B cells which disseminated throughout the node and which expressed monocyte surface markers. Medullary T cells (predominantly CD4) clustered around 1C and expressed CD25 within 2 days of infection. This pattern persisted 4 days post infection, but numbers of CD25 T cells subsequently declined and none were found in the node by 10 days post infection. Altered function of DLN T cells was most obvious in the destruction of DLN germinal centres (GC), particularly the T cell dependent light zones. Although T cell activation marker expression waned, CD3 cells were not depleted from GC light zones or from the node in general. This may suggest that soluble factors play a role in interfering with immunity. Cytokine analysis of DLN cells early in infection demonstrated that production of IL4 within the entire node ceased within 4 days of infection, while in contrast IFNy production remained and has been shown in other experiments to become elevated. The control of B cell proliferation and differentiation depends partially upon the balance between stimulatory IL4 and inhibitory IFNy. The dominant production of IFNy may be leading to the disruption observed in GC by both changing the IL4 production capabilities of GC T cells and directly inhibiting B cell differentiation.In summary, this thesis has shown that T.annulata infected cells posses an innate ability to activate naive T cells. Although all T cell types are activated in pbm, this is dependant upon cytokine release by CD4 cells, subsequently leading to a type I response. In vivo, a similar mechanism leads to activation of DLN T cells primarily by IC. Such interactions do not lead to the induction of an antigen specific immune response, but to the loss of GC and suppression of further T cell activation

The Likelihood Ratio as a tool for Radio Continuum Surveys with SKA precursor telescopes

In this paper we investigate the performance of the likelihood ratio method as a tool for identifying optical and infrared counterparts to proposed radio continuum surveys with SKA precursor and pathfinder telescopes. We present a comparison of the infrared counterparts identified by the likelihood ratio in the VISTA Deep Extragalactic Observations (VIDEO) survey to radio observations with 6, 10 and 15 arcsec resolution. We cross-match a deep radio catalogue consisting of radio sources with peak flux density $>$ 60 $\mu$Jy with deep near-infrared data limited to $K_{\mathrm{s}}\lesssim$ 22.6. Comparing the infrared counterparts from this procedure to those obtained when cross-matching a set of simulated lower resolution radio catalogues indicates that degrading the resolution from 6 arcsec to 10 and 15 arcsec decreases the completeness of the cross-matched catalogue by approximately 3 and 7 percent respectively. When matching against shallower infrared data, comparable to that achieved by the VISTA Hemisphere Survey, the fraction of radio sources with reliably identified counterparts drops from $\sim$89%, at $K_{\mathrm{s}}\lesssim$22.6, to 47% with $K_{\mathrm{s}}\lesssim$20.0. Decreasing the resolution at this shallower infrared limit does not result in any further decrease in the completeness produced by the likelihood ratio matching procedure. However, we note that radio continuum surveys with the MeerKAT and eventually the SKA, will require long baselines in order to ensure that the resulting maps are not limited by instrumental confusion noise.Comment: 10 pages, 7 figures, accepted for publication in mnra

Galaxy pairs in the Sloan Digital Sky Survey - IX: Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer

Interactions between galaxies are predicted to cause gas inflows that can potentially trigger nuclear activity. Since the inflowing material can obscure the central regions of interacting galaxies, a potential limitation of previous optical studies is that obscured Active Galactic Nuclei (AGNs) can be missed at various stages along the merger sequence. We present the first large mid-infrared study of AGNs in mergers and galaxy pairs, in order to quantify the incidence of obscured AGNs triggered by interactions. The sample consists of galaxy pairs and post-mergers drawn from the Sloan Digital Sky Survey that are matched to detections by the Wide Field Infrared Sky Explorer (WISE). We find that the fraction of AGN in the pairs, relative to a mass-, redshift- and environment-matched control sample, increases as a function of decreasing projected separation. This enhancement is most dramatic in the post-merger sample, where we find a factor of 10-20 excess in the AGN fraction compared with the control. Although this trend is in qualitative agreement with results based on optical AGN selection, the mid-infrared selected AGN excess increases much more dramatically in the post-mergers than is seen for optical AGN. Our results suggest that energetically dominant optically obscured AGNs become more prevalent in the most advanced mergers, consistent with theoretical predictions.Comment: 8 pages, 7 figures accepted to MNRAS (with minor revisions

Listening loops and the adapting auditory brain

Analysing complex auditory scenes depends in part on learning the long-term statistical structure of sounds comprising those scenes. One way in which the listening brain achieves this is by analysing the statistical structure of acoustic environments over multiple time courses and separating background from foreground sounds. A critical component of this statistical learning in the auditory brain is the interplay between feedforward and feedback pathways—“listening loops”—connecting the inner ear to higher cortical regions and back. These loops are likely important in setting and adjusting the different cadences over which learned listening occurs through adaptive processes that tailor neural responses to sound environments that unfold over seconds, days, development, and the life-course. Here, we posit that exploring listening loops at different scales of investigation—from in vivo recording to human assessment—their role in detecting different timescales of regularity, and the consequences this has for background detection, will reveal the fundamental processes that transform hearing into the essential task of listening