1,540 research outputs found
Species limits within the Mexican garter snakes of the \u3cem\u3eThamnophis godmani\u3c/em\u3e complex
The highly variable Thamniphis godmani complex of southern Mexico, comprised of four apparently allopatric populations, was examined by using 28 morphological characters scored on 214 specimens. Character values were tested with univariate and multivariate statistics to determine if populations are morphologically distinct. The results suggest that the four populations represent independently evolving lineages. Four species, three previously undescribed, are recognized in the T. godmani complex. A lectotype is designated for T. godmani. For each species, a diagnosis description of holotype or lectotype, summary of interspecific variation, and statement of distribution are provided. Comparisons are made with T. errans, alleged to be the closest relative to members of the complex
A protease inhibitor blocks SOS functions in Escherichia coli: antipain prevents lambda repressor inactivation, ultraviolet mutagenesis, and filamentous growth.
Cryotomography of budding influenza a virus reveals filaments with diverse morphologies that mostly do not bear a genome at their distal end
Influenza viruses exhibit striking variations in particle morphology between strains. Clinical isolates of influenza A virus have been shown to produce long filamentous particles while laboratory-adapted strains are predominantly spherical. However, the role of the filamentous phenotype in the influenza virus infectious cycle remains undetermined. We used cryo-electron tomography to conduct the first three-dimensional study of filamentous virus ultrastructure in particles budding from infected cells. Filaments were often longer than 10 microns and sometimes had bulbous heads at their leading ends, some of which contained tubules we attribute to M1 while none had recognisable ribonucleoprotein (RNP) and hence genome segments. Long filaments that did not have bulbs were infrequently seen to bear an ordered complement of RNPs at their distal ends. Imaging of purified virus also revealed diverse filament morphologies; short rods (bacilliform virions) and longer filaments. Bacilliform virions contained an ordered complement of RNPs while longer filamentous particles were narrower and mostly appeared to lack this feature, but often contained fibrillar material along their entire length. The important ultrastructural differences between these diverse classes of particles raise the possibility of distinct morphogenetic pathways and functions during the infectious process
Independent Validation of the SWMM Green Roof Module
Green roofs are a popular Sustainable Drainage Systems (SuDS) technology. They provide multiple benefits, amongst which the retention of rainfall and detention of runoff are of particular interest to stormwater engineers. The hydrological performance of green roofs has been represented in various models, including the Storm Water Management Model (SWMM). The latest version of SWMM includes a new LID green roof module, which makes it possible to model the hydrological performance of a green roof by directly defining the physical parameters of a green roof’s three layers. However, to date, no study has validated the capability of this module for representing the hydrological performance of an extensive green roof in response to actual rainfall events. In this study, data from a previously-monitored extensive green roof test bed has been utilised to validate the SWMM green roof module for both long-term (173 events over a year) and short-term (per-event) simulations. With only 0.357% difference between measured and modelled annual retention, the uncalibrated model provided good estimates of total annual retention, but the modelled runoff depths deviated significantly from the measured data at certain times (particularly during summer) in the year. Retention results improved (with the difference between modelled and measured annual retention decreasing to 0.169% and the Nash-Sutcliffe Model Efficiency (NSME) coefficient for per-event rainfall depth reaching 0.948) when reductions in actual evapotranspiration due to reduced substrate moisture availability during prolonged dry conditions were used to provide revised estimates of monthly ET. However, this aspect of the model’s performance is ultimately limited by the failure to account for the influence of substrate moisture on actual ET rates. With significant differences existing between measured and simulated runoff and NSME coefficients of below 0.5, the uncalibrated model failed to provide reasonable predictions of the green roof’s detention performance, although this was significantly improved through calibration. To precisely model the hydrological behaviour of an extensive green roof with a plastic board drainage layer, some of the modelling structures in SWMM green roof module require further refinement
Financialization directing strategy
Original article can be found at: http://www.sciencedirect.com/science/journal/01559982 Copyright Elsevier Ltd. DOI: 10.1016/j.accfor.2008.08.001This paper constructs an account of how financialization is directing strategy in the S&P 500. Financialization describes how changes in US accounting regulations require firms to account for the market value of capital market transactions where corporate strategy is not simply concerned with delivering value creation but also reacting to value absorption in an era of shareholder value. Financialization is directing strategy and arbitrage to modify stakeholder financial settlements where an increased share of income is extracted as surplus cash and more of this cash from operations is being distributed to shareholders. Share buy-backs account for a substantial increase in the share of corporate cash distributed to shareholders in the S&P 500 which, we argue, reflects a strategic process of value creation and value absorption.Peer reviewe
Theoretical Spectra and Atmospheres of Extrasolar Giant Planets
We present a comprehensive theory of the spectra and atmospheres of
irradiated extrasolar giant planets. We explore the dependences on stellar
type, orbital distance, cloud characteristics, planet mass, and surface
gravity. Phase-averaged spectra for specific known extrasolar giant planets
that span a wide range of the relevant parameters are calculated, plotted, and
discussed. The connection between atmospheric composition and emergent spectrum
is explored in detail. Furthermore, we calculate the effect of stellar
insolation on brown dwarfs. We review a variety of representative observational
techniques and programs for their potential for direct detection, in light of
our theoretical expectations, and we calculate planet-to-star flux ratios as a
function of wavelength. Our results suggest which spectral features are most
diagnostic of giant planet atmospheres and reveal the best bands in which to
image planets of whatever physical or orbital characteristics.Comment: 47 pages, plus 36 postscript figures; with minor revisions, accepted
to the Astrophysical Journal, May 10, 2003 issu
Rendering an Account: An Open-State Archive in Postgraduate Supervision
The paper begins with a brief account of the transformation of research degree studies under the pressures of global capitalism and neo-liberal governmentality. A parallel transformation is occurring in the conduct of research through the use of information and communication technologies. Yet the potential of ICTs to shape practices of surveillance or to produce new student-supervisor relations and enhance the processes of developing the dissertation has received almost no critical attention. As doctoral supervisor and student, we then describe the features and uses of a web-based open state archive of the student's work-in-progress, developed by the student and accessible to his supervisor. Our intention was to encourage more open conversations between data and theorising, student and supervisor, and ultimately between the student and professional community. However, we recognise that relations of accountability, as these have developed within a contemporary "audit revolution" (Power, 1994, 1997) in universities, create particular "lines of visibility" (Munro, 1996). Thus while the open-state archive may help to redefine in less managerial terms notions of quality, transparency, flexibility and accountability, it might also make possible greater supervisory surveillance. How should we think about the panoptical potential of this archive? We argue that the diverse kinds of interactional patterns and pedagogical intervention it encourages help to create shifting subjectivities. Moreover, the archive itself is multiple, in bringing together an array of diverse materials that can be read in various ways, by following multiple paths. It therefore constitutes a collage, which we identify as a mode of cognition and of accounting distinct from but related to argument and narrative. As a more "open" text (Iser, 1978) it has an indeterminacy which may render it less open to abuse for the technologies of managerial accountability
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