7,433 research outputs found
The radial acceleration relation is a natural consequence of the baryonic Tully-Fisher relation
Galaxies covering several orders of magnitude in stellar mass and a variety
of Hubble types have been shown to follow the "Radial Acceleration Relation"
(RAR), a relationship between , the observed circular acceleration
of the galaxy, and , the acceleration due to the total baryonic
mass of the galaxy. For accelerations above ,
traces , asymptoting to the 1:1 line. Below this
scale, there is a break in the relation such that . We show that the RAR slope, scatter and the acceleration scale are
all natural consequences of the well-known baryonic Tully-Fisher relation
(BTFR). We further demonstrate that galaxies with a variety of baryonic and
dark matter (DM) profiles and a wide range of dark halo and galaxy properties
(well beyond those expected in CDM) lie on the RAR if we simply require that
their rotation curves satisfy the BTFR. We explore conditions needed to break
this degeneracy: sub-kpc resolved rotation curves inside of "cored"
DM-dominated profiles and/or outside kpc could lie on BTFR but
deviate in the RAR, providing new constraints on DM.Comment: 5 pages, submitted to MNRA
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Effects of sheep grazing on abundance and predators of field vole (<i>Microtus agrestis</i>) in upland Britain
A technique using fresh feeding signs as an index of density was validated and used to survey the effects of sheep grazing on vole population densities in four upland habitats in the northern Peak District National Park, UK. In grazed areas Molinia caerulea grasslands supported most voles, Nardus stricta grasslands supported fewer and Eriophorum vaginatum and Calluna vulgaris-dominated areas supported least. There were highly significant negative relationships between vole sign density and sheep numbers in these habitats. Where sheep were excluded, these same habitats had between three and nine times higher sign densities, corresponding to between 1.5 and 2.5 times greater field vole densities. Population estimates of voles and predators such as short-eared owl approximately doubled under reduced grazing. Reducing sheep numbers in upland areas may therefore be critical in encouraging the recovery of predatory birds in the uplands
Catalytically generated acyl triazoliums as versatile acylating reagents and progress toward the total synthesis of okilactomycin
2013 Spring.Includes bibliographical references.The first chapter of this dissertation describes the development of reactions involving the NHC-catalyzed acylation of carbon and nitrogen nucleophiles. The overall goal of this work was to expand the scope of the NHC-redox reaction manifold and improve its applicability to the synthesis of products that would be useful to the organic chemistry community. An efficient and simple procedure for the preparation of amides from amine hydrochloride salts and α,β-unsaturated aldehydes was developed. This procedure was then applied to the asymmetric synthesis of α-fluoroamides which are valuable building blocks for the preparation of fluorinated compounds that are highly sought after in pharmaceutical, material, and agrichemical applications. The second chapter describes efforts toward the total synthesis of the complex polyketide natural product okilactomycin, enabled by the rhodium-catalyzed desymmetrization of 3,5-dimethylglutaric anhydride developed previously by our group. Progress includes construction of the entire carbon skeleton in two fragments, poised to be unified and elaborated to the natural product by closely precedented steps. This progress demonstrates the potential of the catalytic, enantioselective desymmetrization of anhydrides to build complexity in rapid fashion
Can aggregate quarry silt lagoons provide resources for wading birds?
Wading birds have declined across Europe as the intensification of lowland agriculture has resulted in the loss and degradation of wetland areas. Lowland aggregate extraction sites that incorporate areas of fine, waste sediments deposited in silt lagoons have the potential to be restored for wader conservation. We set out to determine the potential value of silt lagoons to wading birds by comparing the water quality, sediment profiles, aquatic invertebrate abundance and diversity (prey availability) and wader site use at five sites representing various stages of active aggregate extraction and restoration for conservation purposes. Wader counts were conducted monthly over a twelve month period using replicated scan samples, and the invertebrate communities studied during the breeding and autumn migration season (June–September). Water quality variables were similar between sites, but sediments from active quarries were dominated by moderately sorted fine sands in comparison to the coarser sediment profiles of restored areas. June and September there was no significant difference in invertebrate diversity between sites, however richness was significantly lower on quarry sites and total abundance a factor of ten higher at restored sites than on silt lagoons, with the dominant taxa similar across all sites. Waders used all sites; albeit at lower abundance and richness on silt lagoons and two species were recorded breeding on active silting sites. We conclude that the fine, uniform sediments of modern silt lagoons limited invertebrate diversity and abundance, diminishing the value of silt lagoons to waders. Simple low-cost intervention measures increasing substrate heterogeneity and creating temporary ponds could increase invertebrate richness and abundance, and enhance the conservation potential of these sites
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Using a citizen science tool to model the health benefits of roadside trees
Center for the Study of Religion and American Culture NEH Summer Institute for Teachers July 12-30, 2010
poster abstractThis institute will support the studies of twenty-five talented teachers from across the nation as they join with nationally renowned scholars to explore how religion has shaped, and been shaped by, the American experience. The institute directors, Philip Goff, Arthur Farnsley, and Rachel Wheeler, are all noted scholars in their field, whose work encompasses a wide range of subject matter and methodologies. The institute will enable participants from many different fields to develop new materials on American religion that can be incorporated into their current curricula. An English teacher introducing Uncle Tom’s Cabin, or The Adventures of Huckleberry Finn, for instance, will be better prepared to discuss the nexus of religion and race in the context of nineteenth-century America. A civics teacher focusing on the origins of the American government will be able to incorporate discussion about the religion of the founders and the ways in which the First Amendment has shaped American society
Infrastructure for Rapid Development of Java GUI Programs
The Java Application Shell (JAS) is a software framework that accelerates the development of Java graphical-user-interface (GUI) application programs by enabling the reuse of common, proven GUI elements, as distinguished from writing custom code for GUI elements. JAS is a software infrastructure upon which Java interactive application programs and graphical user interfaces (GUIs) for those programs can be built as sets of plug-ins. JAS provides an application- programming interface that is extensible by application-specific plugins that describe and encapsulate both specifications of a GUI and application-specific functionality tied to the specified GUI elements. The desired GUI elements are specified in Extensible Markup Language (XML) descriptions instead of in compiled code. JAS reads and interprets these descriptions, then creates and configures a corresponding GUI from a standard set of generic, reusable GUI elements. These elements are then attached (again, according to the XML descriptions) to application-specific compiled code and scripts. An application program constructed by use of JAS as its core can be extended by writing new plug-ins and replacing existing plug-ins. Thus, JAS solves many problems that Java programmers generally solve anew for each project, thereby reducing development and testing time
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