1,121 research outputs found

    The Infrared Emission from the Narrow Line Region

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    We present models for the mid- and far- infrared emission from the Narrow Line Region (NLR) of Active Galactic Nuclei (AGN). Using the MAPPINGS III code we explore the effect of typical NLR parameters on the spectral characteristics of the IR emission. These include useful IR emission line ratio diagnostic diagrams for the determination of these parameters, as well as Star formation--AGN mixing diagnostics. We also examine emission line to continuum correlations which would assist in separating the IR emission arising from the NLR from that coming from the inner torus. We find for AGN like NGC 1068 and NGC 4151 that the NLR only contributes ~10% to the total IRAS 25 mum flux, and that other components such as a dusty torus are necessary to explain the total AGN IR emission.Comment: 15 pages, 12 figures, accepted for publication in A&A. Paper with full resolution figures available at http://www.mpa-garching.mpg.de/~brent/publications/bgrovesnlrIRpaper.pd

    Telescope Time Without Tears: A Distributed Approach to Peer Review

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    The procedure that is currently employed to allocate time on telescopes is horribly onerous on those unfortunate astronomers who serve on the committees that administer the process, and is in danger of complete collapse as the number of applications steadily increases. Here, an alternative is presented, whereby the task is distributed around the astronomical community, with a suitable mechanism design established to steer the outcome toward awarding this precious resource to those projects where there is a consensus across the community that the science is most exciting and innovative.Comment: 9 pages, accepted for publication in Astronomy & Geophysic

    Winning Wirzburger and Defeating the Blaine Amendments: Arguing Present Efficacy Instead of Past Intent

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    The case of Wirzburger v. Galvin, currently on a writ of certiorari to the Supreme Court, may set the tone for all religious discrimination cases in the future. Massachusetts’ constitutional amendments that proscribe any citizen initiatives from either dealing with religion in general or attempting to repeal the states Blaine Amendment are at issue in the case. Petitioner’s counsel, the Becket Fund, rightly views this case as paramount in the long-march to victory over the anti-Catholic Blaine Amendments still codified in 37 state constitutions. However, they have lost almost every stage of the case. This article argues that Wirzburger and other anti-Blaine litigation should experience a paradigm shift. No longer should litigators argue the Blaine’s “past intent” to discriminate against religious persons, and particularly Catholics. The 2004 Locke v. Davey decision confirms the Supreme Court’s unwillingness to affirm the animus behind the Blaine Amendments. Wirzburger and future cases should pin their claims upon the higher ground of nonpersecution, outlined in the 1993 Lukumi Babalu Aye case. The principles of neutrality, general applicability and non-exemption serve as fundamental tenets of this argumentative direction. This article argues that these tenets boost the strength of petitioner’s Constitutional claims. Wirzburger must be won. The veil of anti-Catholic discrimination must finally be lifted and the bigoted Blaine’s repealed. Only by pinning anti-Blaine litigation upon the doctrine of nonpersecution and arguing present efficacy instead of past intent, will these hopes materialize

    Molecular and Computational Methods for Cellular State Control

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    The control of cellular state has many promising applications, including stem cell biology and regenerative medicine, biofuel production, and gene therapy. This dissertation demonstrates a comprehensive approach to cellular state control at the transcriptional level. We introduce a novel algorithm, NetSurgeon, which utilizes genome-wide gene regulatory networks to identify interventions that will force a cell toward a desired expression state. Following extensive in silico validation, we applied NetSurgeon to S. cerevisiae biofuel production, generating interventions designed to promote a fermentative state during xylose catabolism. Our selected interventions successfully promoted a fermentative transcriptional state and generated strains with higher xylose import rates, improved xylose integration and increased ethanol production rates. We then step down to a single gene level and exhibit a cis-engineering strategy that enables precise expression control. We demonstrate that synthetic promoters can be functionally decomposed into individual components that can be characterized in isolation and used to train a composite model capable of predicting the action of the full system. These findings represent significant progress towards the insertion of orthogonal control circuits into the cell for the control of gene expression. Taken together, this dissertation represents an integrative process of quantitative measurement, modeling, and intervention that comprehensively examines methods for cellular state control at the genome-wide and gene levels

    Studies of the influence of physical properties, in particular particle size, on the flow behaviour of emulsions

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    The physical properties of concentrated solid–liquid emulsion systems typical of materials important in the pharmaceutical and cosmetics industries are investigated. [Continues.

    Gelatin behaviour in dilute aqueous solution : designing a nanoparticulate formulation

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    Although it has been claimed that nanoparticles can be produced from gelatin, a naturally occurring polypeptide, the commercial conversion of animal collagen to gelatin results in a heterogeneous product with a wide molecular-weight range. This is probably responsible for the widely observed variation in the experimental conditions required for nanoparticle formation. In this study, 0.2% w/v aqueous B225 gelatin solutions were incubated under various conditions of time, temperature, pH and ethanol concentration and characterized by both size-exclusion high-performance liquid chromatography (HPLC) and dynamic light scattering. Gelatin was shown to be denatured when the temperature was increased to 37°C (approx.) and the rate of renaturation was optimized over the temperature range 7–20°Cat pH5.0, equivalent to the isoelectric point (IEP). The molecular-weight profile remained unchanged at 37°C (approx.) in the pH range 5–7. When the gelatin solutions were mixed with ethanol, higher-molecular-weight fractions (microgel, δ and ζ fractions, all with molecular weights > 700 kDa) precipitated at ethanol concentrations lower than those required to precipitate the lower molecular weight material (< 700 kDa), with maximum precipitation occurring close to the isoelectric point (pH 5.0). The molecular weight profile of gelatin in solution is evidently critically affected in a time-dependent manner by both pH and temperature. These two factors influence the noncovalent interactions responsible for the molecular structure of gelatin. The molecular weight profiles, in turn, affect the phase behaviour of gelatin in hydroalcoholic solutions. Systematically investigating the effect of time, temperature, pH and ethanol concentration on the molecular-weight-distribution profile of a gelatin solution enabled a robust method to be developed for the preparation of colloidal dispersions of non-aggregated gelatin nanoparticles 220–250 nm in diameter. This contrasts with the multiparticulate aggregates produced by earlier literature methods.peer-reviewe

    Separate compilation of structured documents

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    This paper draws a parallel between document preparation and the traditional processes of compilation and link editing for computer programs. A block-based document model is described which allows for separate compilation of various portions of a document. These portions are brought together and merged by a linker program, called dlink, whose pilot implementation is based on ditroff and on its underlying intermediate code. In the light of experiences with dlink the requirements for a universal object-module language for documents are discussed. These requirements often resemble the characteristics of the intermediate codes used by programming-language compilers but with interesting extra constraints which arise from the way documents are executed
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