302 research outputs found
An Archaeological Survey of the Medio Creek Water Treatment Plant, Bexar County, Texas
The Center for Archaeological Research (CAR) of The University of Texas at San Antonio conducted a pedestrian survey and subsurface backhoe testing for cultural resources on the raw water pipeline route for the Medio Creek Water Treatment Plant and sites of the treatment plant and the raw water intake on the bank of the Medina River in southwestern Bexar County, Texas. The pipeline route traverses ca. 1.6 km of alluvial terrace associated with the Medina River and Medio Creek, including a crossing of Medio Creek. Limited geomorphological observations also were made. Few cultural remains were encountered, none diagnostic of a particular prehistoric period. One site, 41BX1259, was recorded at the planned location of the treatment plant. CAR determined that no significant cultural resources would be affected by construction of the intake facility or pipeline and therefore recommends that the project sponsor be allowed to proceed as planned
Analytic, Group-Theoretic Density Profiles for Confined, Correlated N-Body Systems
Confined quantum systems involving identical interacting particles are to
be found in many areas of physics, including condensed matter, atomic and
chemical physics. A beyond-mean-field perturbation method that is applicable,
in principle, to weakly, intermediate, and strongly-interacting systems has
been set forth by the authors in a previous series of papers. Dimensional
perturbation theory was used, and in conjunction with group theory, an analytic
beyond-mean-field correlated wave function at lowest order for a system under
spherical confinement with a general two-body interaction was derived. In the
present paper, we use this analytic wave function to derive the corresponding
lowest-order, analytic density profile and apply it to the example of a
Bose-Einstein condensate.Comment: 15 pages, 2 figures, accepted by Physics Review A. This document was
submitted after responding to a reviewer's comment
The theory of pulsar winds and nebulae
We review current theoretical ideas on pulsar winds and their surrounding
nebulae. Relativistic MHD models of the wind of the aligned rotator, and of the
striped wind, together with models of magnetic dissipation are discussed. It is
shown that the observational signature of this dissipation is likely to be
point-like, rather than extended, and that pulsed emission may be produced. The
possible pulse shapes and polarisation properties are described. Particle
acceleration at the termination shock of the wind is discussed, and it is
argued that two distinct mechanisms must be operating, with the first-order
Fermi mechanism producing the high-energy electrons (above 1 TeV) and either
magnetic annihilation or resonant absorption of ion cyclotron waves responsible
for the 100 MeV to 1 TeV electrons. Finally, MHD models of the morphology of
the nebula are discussed and compared with observation.Comment: 33 pages, to appear in Springer Lecture Notes on "Neutron stars and
pulsars, 40 years after the discovery", ed W.Becke
Foundations of Black Hole Accretion Disk Theory
This review covers the main aspects of black hole accretion disk theory. We
begin with the view that one of the main goals of the theory is to better
understand the nature of black holes themselves. In this light we discuss how
accretion disks might reveal some of the unique signatures of strong gravity:
the event horizon, the innermost stable circular orbit, and the ergosphere. We
then review, from a first-principles perspective, the physical processes at
play in accretion disks. This leads us to the four primary accretion disk
models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin)
disks, slim disks, and advection-dominated accretion flows (ADAFs). After
presenting the models we discuss issues of stability, oscillations, and jets.
Following our review of the analytic work, we take a parallel approach in
reviewing numerical studies of black hole accretion disks. We finish with a few
select applications that highlight particular astrophysical applications:
measurements of black hole mass and spin, black hole vs. neutron star accretion
disks, black hole accretion disk spectral states, and quasi-periodic
oscillations (QPOs).Comment: 91 pages, 23 figures, final published version available at
http://www.livingreviews.org/lrr-2013-
The Genome and Methylome of a Beetle with Complex Social Behavior,Nicrophorus vespilloides(Coleoptera: Silphidae)
Testing for conserved and novelmechanisms underlying phenotypic evolution requires a diversity of genomes available for comparisonspanning multiple independent lineages. For example, complex social behavior in insects has been investigated primarily witheusocial lineages, nearly all of which are Hymenoptera. If conserved genomic influences on sociality do exist, we need data from awider range of taxa that also vary in their levels of sociality. Here,we present the assembled and annotated genome of the subsocialbeetle Nicrophorus vespilloides, a species long used to investigate evolutionary questions of complex social behavior. We used thisgenome to address two questions. First, do aspects of life history, such as using a carcass to breed, predict overlap in gene modelsmore strongly than phylogeny? We found that the overlap in gene models was similar between N. vespilloides and all other insectgroups regardless of life history. Second, like other insects with highly developed social behavior but unlike other beetles, doesN. vespilloides have DNA methylation?We found strong evidence for an active DNA methylation system. The distribution of methylationwassimilar to other insects with exons having themostmethylatedCpGs. Methylation status appears highly conserved; 85%of themethylated genes in N. vespilloides are alsomethylated in the hymentopteran Nasonia vitripennis. The addition of this genomeadds a coleopteran resource to answer questions about the evolution and mechanistic basis of sociality and to address questionsabout the potential role of methylation in social behavior
Endomyocardial Fibrosis: Still a Mystery after 60 Years
The pathologist Jack N. P. Davies identified endomyocardial fibrosis in Uganda in 1947. Since that time, reports of this restrictive cardiomyopathy have come from other parts of tropical Africa, South Asia, and South America. In Kampala, the disease accounts for 20% of heart disease patients referred for echocardiography. We conducted a systematic review of research on the epidemiology and etiology of endomyocardial fibrosis. We relied primarily on articles in the MEDLINE database with either “endomyocardial fibrosis” or “endomyocardial sclerosis” in the title. The volume of publications on endomyocardial fibrosis has declined since the 1980s. Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution
Diversity and abundance of solitary and primitively eusocial bees in an urban centre: a case study from Northampton (England)
The apparent reduction of solitary and primitively eusocial bees populations has remained a huge concern over the past few decades and urbanisation is considered as one of the factors affecting bees at different scales depending on bee guild. As urbanisation is increasing globally it necessitates more research to understand the complex community dynamics of solitary and primitively eusocial bees in urban settings. We investigated the urban core of a British town for diversity and abundance of solitary bees using standardized methods, and compared the results with nearby meadows and nature reserves. The study recorded 48 species within the town, about 22 % of the total species and 58 % of the genera of solitary bees in the United Kingdom. Furthermore we found the urban core to be more diverse and abundant in solitary and primitively eusocial bees compared to the meadows and nature re-serves. Of particular note was an urban record of the nationally rare Red Data Book species Coelioxys quadridentata and its host Anthophora quadrimaculata. This research demonstrates that urban settings can contribute significantly to the conservation of solitary and primitively eusocial bees in Britain
Is there really a dichotomy in AGN jet power?
To gain new insights into the radio-loud/radio-quiet dichotomy reported for
active galactic nuclei, we examine radio loudness as a function of Eddington
ratio for a previously published sample of 199 AGN from five different
populations. After initially considering radio loudnesses derived using total
radio luminosities, we repeat the investigation using core radio luminosities
only, applying a previously established mass correction for these core
luminosities. In both cases, for Eddington ratios < 1 per cent, Fanaroff-Riley
type I and broad-line radio galaxies are on average more radio-loud than
Seyfert and low-ionization nuclear emission-line region galaxies. However, the
distribution of radio loudnesses for the mass-corrected, core-only sample is
much narrower than that of the clearly bimodal total radio loudness
distribution. The advantages and disadvantages of using core- or lobe-dominated
radio luminosity as a measure of instantaneous jet power are discussed. We
furthermore compare the core and total radio luminosities for the entire
sample, as well as illustrating the importance of the mass term by comparing
the AGN with a sample of black hole X-ray binaries. We conclude that if the
mass-corrected core radio luminosity is a good measure of jet power, then black
hole spin may have considerably less impact on jet power than previously
reported, or that our sample does not include the extremes of spin. If the
spread in jet power is small then we suggest that characteristics of the
ambient environment and/or the radio source age could be equally as important
in producing a radio-loud/radio-quiet dichotomy seen in total radio luminosity.Comment: Accepted for publication in MNRAS. Minor typos correcte
Receptor Activation and Inositol Lipid Hydrolysis in Neural Tissues
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66228/1/j.1471-4159.1987.tb05618.x.pd
Introduction: Toward an Engaged Feminist Heritage Praxis
We advocate a feminist approach to archaeological heritage work in order to transform heritage practice and the production of archaeological knowledge. We use an engaged feminist standpoint and situate intersubjectivity and intersectionality as critical components of this practice. An engaged feminist approach to heritage work allows the discipline to consider women’s, men’s, and gender non-conforming persons’ positions in the field, to reveal their contributions, to develop critical pedagogical approaches, and to rethink forms of representation. Throughout, we emphasize the intellectual labor of women of color, queer and gender non-conforming persons, and early white feminists in archaeology
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