396 research outputs found
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The Highsmith Men, Texas Rangers
The Highsmith Men is a general historical narrative of four prominent men who happened to be Texas Rangers. The story begins in Texas in 1830 and traces the lives of Samuel Highsmith, his nephew, Benjamin Franklin Highsmith, and Samuels's sons, Malcijah and Henry Albert Highsmith, who was the last of the four to pass away, in 1930. During this century the four Highsmiths participated in nearly every landmark event significant to the history of Texas. The Highsmith men also participated in numerous other engagements as well. Within this framework the intent of The Highsmith Men is to scrutinize the contemporary scholarly conceptions of the early Texas Rangers as an institution by following the lives of these four men, who can largely be considered common folk settlers. This thesis takes a bottom up approach to the history of Texas, which already maintains innumerable accounts of the sometimes true and, sometimes not, larger than life figures that Texas boasts. For students pursuing studies in the Texas, the American West, the Mexican American War, or Civil War history, this regional history may be of some use. The early Texas Rangers were generally referred to as "Minute Men" or "Volunteer Militia" until 1874. In this role, the Highsmith men participated in many historic Texas engagements including but not limited to the Siege of Béxar, the battle of the Alamo, San Jacinto, the Cordova Rebellion, Plum Creek, the Mexican Invasions of 1842, the Mexican War, the Civil War, Salado Creek, Brushy Creek, and the capture of Sam Bass. Not only did people like the Highsmiths, who were largely considered "common folk," participate in these battles, they were also Texas Rangers. None of the Highsmith men were full time Texas Rangers, which discredits prominent stereotypes. The Highsmith Men shows that the Texas Ranger institution and the history of Texas itself was not dominated by larger than life historical characters, rather those noted figures maintained their widespread fame by building their successes on the backs of these men
Highly Variable Extinction and Accretion in the Jet-driving Class I Type Young Star PTF 10nvg (V2492 Cyg, IRAS 20496+4354)
We report extensive new photometry and spectroscopy of the highly variable
young stellar object PTF 10nvg including optical and near-infrared time series
data as well as mid-infrared and millimeter data. Following the previously
reported 2010 rise, during 2011 and 2012 the source underwent additional
episodes of brightening and dimming events including prolonged faint states.
The observed high-amplitude variations are largely consistent with extinction
changes having a 220 day quasi-periodic signal. Spectral evolution includes not
only changes in the spectral slope but correlated variation in the prominence
of TiO/VO/CO bands and atomic line emission, as well as anticorrelated
variation in forbidden line emission which, along with H_2, dominates optical
and infrared spectra at faint epochs. Neutral and singly-ionized atomic species
are likely formed in an accretion flow and/or impact while the origin of
zero-velocity atomic LiI 6707 in emission is unknown. Forbidden lines,
including several rare species, exhibit blueshifted emission profiles and
likely arise from an outflow/jet. Several of these lines are also seen
spatially offset from the continuum source position, presumably in a shocked
region of an extended jet. CARMA maps resolve on larger scales a spatially
extended outflow in mm-wavelength CO. We attribute the observed photometric and
spectroscopic behavior in terms of occultation of the central star as well as
the bright inner disk and the accretion/outflow zones that renders shocked gas
in the inner part of the jet amenable to observation at the faint epochs. We
discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps
analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or
GM Cep) high-amplitude variability phenomena.Comment: accepted to AJ - in press (74 pages
The polaroid image as photo-object
This article is part of a larger project on the cultural history of Polaroid photography and draws on research done at the Polaroid Corporate archive at Harvard and at the Polaroid company itself. It identifies two cultural practices engendered by Polaroid photography, which, at the point of its extinction, has briefly flared into visibility again. It argues that these practices are mistaken as novel but are in fact rediscoveries of practices that stretch back as many as five decades. The first section identifies Polaroid image-making as a photographic equivalent of what Tom Gunning calls the ‘cinema of attractions’. That is, the emphasis in its use is on the display of photographic technologies rather than the resultant image. Equally, the common practice, in both fine art and vernacular circles, of making composite pictures with Polaroid prints, draws attention from image content and redirects it to the photo as object
Kinetics of H2–O2–H2O redox equilibria and formation of metastable H2O2 under low temperature hydrothermal conditions
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 75 (2011): 1594-1607, doi:10.1016/j.gca.2010.12.020.Hydrothermal experiments were conducted to evaluate the kinetics of H2(aq)
oxidation in the homogeneous H2-O2-H2O system at conditions reflecting
subsurface/near-seafloor hydrothermal environments (55-250 oC and 242-497 bar). The
kinetics of the water-forming reaction that controls the fundamental equilibrium between
dissolved H2(aq) and O2(aq), are expected to impose significant constraints on the redox
gradients that develop when mixing occurs between oxygenated seawater and high-
temperature anoxic vent fluid at near-seafloor conditions. Experimental data indicate that,
indeed, the kinetics of H2(aq)-O2(aq) equilibrium become slower with decreasing
temperature, allowing excess H2(aq) to remain in solution. Sluggish reaction rates of H2(aq)
oxidation suggest that active microbial populations in near-seafloor and subsurface
environments could potentially utilize both H2(aq) and O2(aq), even at temperatures lower
than 40 oC due to H2(aq) persistence in the seawater/vent fluid mixtures. For these H2-O2
disequilibrium conditions, redox gradients along the seawater/hydrothermal fluid mixing
interface are not sharp and microbially-mediated H2(aq) oxidation coupled with a lack of
other electron acceptors (e.g. nitrate) could provide an important energy source available
at low-temperature diffuse flow vent sites.
More importantly, when H2(aq)-O2(aq) disequilibrium conditions apply, formation
of metastable hydrogen peroxide is observed. The yield of H2O2(aq) synthesis appears to
be enhanced under conditions of elevated H2(aq)/O2(aq) molar ratios that correspond to
abundant H2(aq) concentrations. Formation of metastable H2O2 is expected to affect the
distribution of dissolved organic carbon (DOC) owing to the existence of an additional
strong oxidizing agent. Oxidation of magnetite and/or Fe++ by hydrogen peroxide could
also induce formation of metastable hydroxyl radicals (•OH) through Fenton-type
reactions, further broadening the implications of hydrogen peroxide in hydrothermal environments.This research was conducted with partial support from the NSF
OCE-0752221 and the Geophysical Laboratory Postdoctoral Fellowship. We would also
like to acknowledge contributions by the W.M. Keck Foundation and Shell towards
supporting the hydrothermal lab at the Geophysical Lab. SMS acknowledges support
from NSF OCE-0452333 and the Alfried-Krupp Wissenschaftskolleg Greifswald
(Germany), while WES acknowledges support from NSF grants OCE-0549457 and OCE-
0813861
Accretion, Outflows, and Winds of Magnetized Stars
Many types of stars have strong magnetic fields that can dynamically
influence the flow of circumstellar matter. In stars with accretion disks, the
stellar magnetic field can truncate the inner disk and determine the paths that
matter can take to flow onto the star. These paths are different in stars with
different magnetospheres and periods of rotation. External field lines of the
magnetosphere may inflate and produce favorable conditions for outflows from
the disk-magnetosphere boundary. Outflows can be particularly strong in the
propeller regime, wherein a star rotates more rapidly than the inner disk.
Outflows may also form at the disk-magnetosphere boundary of slowly rotating
stars, if the magnetosphere is compressed by the accreting matter. In isolated,
strongly magnetized stars, the magnetic field can influence formation and/or
propagation of stellar wind outflows. Winds from low-mass, solar-type stars may
be either thermally or magnetically driven, while winds from massive, luminous
O and B type stars are radiatively driven. In all of these cases, the magnetic
field influences matter flow from the stars and determines many observational
properties. In this chapter we review recent studies of accretion, outflows,
and winds of magnetized stars with a focus on three main topics: (1) accretion
onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and
(3) winds from isolated massive magnetized stars. We show results obtained from
global magnetohydrodynamic simulations and, in a number of cases compare global
simulations with observations.Comment: 60 pages, 44 figure
Velocity dispersion measurements of dwarf galaxies in the Coma cluster - implications for the structure of the fundamental plane
We present intermediate-resolution spectroscopic data for a set of dwarf and
giant galaxies in the Coma Cluster, with -20.6 < M_R < -15.7. The photometric
and kinematic properties of the brighter galaxies can be cast in terms of
parameters which present little scatter with respect to a set of scaling
relations known as the Fundamental Plane. To determine the form of these
fundamental scaling relations at lower luminosities, we have measured velocity
dispersions for a sample comprising 69 galaxies on the border of the dwarf and
giant regime. Combining these data with our photometric survey, we find a tight
correlation of luminosity and velocity dispersion, L \propto \sigma^{2.0},
substantially flatter than the Faber-Jackson relation characterising giant
elliptical galaxies. In addition, the variation of mass-to-light ratio with
velocity dispersion is quite weak in our dwarf sample: M/L \propto
\sigma^{0.2}. Our overall results are consistent with theoretical models
invoking large-scale mass removal and subsequent structural readjustment, e.g.,
as a result of galactic winds.Comment: 15 pages, 11 figures, 1 table. MNRAS, in pres
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Potentiating antibacterial activity by predictably enhancing endogenous microbial ROS production
The ever-increasing incidence of antibiotic-resistant infections combined with a weak pipeline of new antibiotics has created a global public health crisis1. Accordingly, novel strategies for enhancing our antibiotic arsenal are needed. As antibiotics kill bacteria in part by inducing reactive oxygen species (ROS)2–4, we reasoned that targeting microbial ROS production might potentiate antibiotic activity. Here we show that ROS production can be predictably enhanced in Escherichia coli, increasing the bacteria’s susceptibility to oxidative attack. We developed an ensemble, genome-scale metabolic modeling approach capable of predicting ROS production in E. coli. The metabolic network was systematically perturbed and its flux distribution analyzed to identify targets predicted to increase ROS production. In silico–predicted targets were experimentally validated and shown to confer increased susceptibility to oxidants. Validated targets also increased susceptibility to killing by antibiotics. This work establishes a systems-based method to tune ROS production in bacteria and demonstrates that increased microbial ROS production can potentiate killing by oxidants and antibiotics
‘Not All That Is White Is Lime’—White Substances from Archaeological Burial Contexts: Analyses and Interpretations
YesArchaeological burial contexts may include a variety of white substances, but few analyses have been published. This study reports on the physico‐chemical characterization of such residues from seven archaeological sites. It is often assumed that white materials from burial contexts are lime. Our findings demonstrate that they can be gypsum, calcite (chalk), aragonite, brushite, degraded metal, natural (gum) resins or synthetic polymer–based products. These may be present as the result of diagenetic processes, funerary practices or modern contamination. This paper provides an analytical approach for the holistic investigation of white materials encountered in burial contexts.Investments for the future’ (IdEx Bordeaux ANR‐10‐IDEX‐03‐02). Grant Number: ANR‐10‐IDEX‐03‐02; Collaborative Projects of the France‐Stanford Center for Interdisciplinary Studies; Collaborative Projects of the France–Stanford Center; French State. Grant Number: IdEx Bordeaux ANR‐10‐IDEX‐03‐02; Northern Archaeological Associates Ltd; PACEA; Wessex Archaeology; INRAP; Mersea Island Museum Trust; Vatican's Pontifical Commission for Sacred Archaeology; University of Reading; IRAMAT-CRP2A; University of Bradford; CEREG
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Author Correction: Expanded encyclopaedias of DNA elements in the human and mouse genomes
Online Correction for: https://doi.org/10.1038/s41586-020-2493-4 | Erratum for https://bura.brunel.ac.uk/handle/2438/21299In the version of this article initially published, two members of the ENCODE Project Consortium were missing from the author list. Rizi Ai (Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA) and Shantao Li (Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT, USA) are now included in the author list. These errors have been corrected in the online version of the article : 'Expanded encyclopaedias of DNA elements in the human and mouse genomes'.https://www.nature.com/articles/s41586-021-04226-3https://www.nature.com/articles/s41586-021-04226-
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