735 research outputs found
Erratum: "Groups of Galaxies in the Two Micron All Sky Redshift Survey" (ApJ, 655, 790 [2007])
Quaternary faulting in the New Madrid seismic zone in southernmost Illinois
U.S. Geological Survey, Department of the Interior, National Earthquake Hazards Reduction Program Award No. 1434-95-G-2525Ope
2MTF I. The Tully-Fisher Relation in the 2MASS J, H and K Bands
The 2 Micron All-Sky Survey (2MASS) Tully-Fisher Survey (2MTF) aims to
measure Tully-Fisher (TF) distances to all bright inclined spirals in the 2MASS
Redshift Survey (2MRS). Essential to this project is a universal calibration of
the TF relation in the 2MASS J (1.2 um), H (1.6 um) and K (2.2 um) bands. We
present the first bias corrected or universal TF template in these bands. We
find that the slope of the TF relation becomes steeper as the wavelength
increases being close to L \propto v^4 in K-band and L \propto v^3.6 in J and
H-bands. We also investigate the dependence on galaxy morphology showing that
in all three bands the relation is steeper for later type spirals which also
have a dimmer TF zeropoint than earlier type spirals. We correct the final
relation to that for Sc galaxies. Finally we study the scatter from the TF
relation fitting for a width dependent intrinsic scatter which is not found to
vary significantly with wavelength.Comment: 13 pages, 5 figures. AJ, accepted (scheduled for June 2008). v2 is as
accepted by AJ and includes only minor textual changes from v1. v3 includes a
3 page erratum published as Masters et al. 2014. A coding error was
discovered and corrected, resulting in small changes in the slope and offsets
offsets of the TF relation. All qualitative results still hold. We apologise
for the inconvenienc
Groups of Galaxies in the Two Micron All-Sky Redshift Survey
We present the results of applying a percolation algorithm to the initial
release of the Two Micron All-Sky Survey Extended Source Catalog, using
subsequently measured redshifts for almost all of the galaxies with K < 11.25
mag. This group catalog is based on the first near-IR all-sky flux-limited
survey that is complete to |b| = 5 deg. We explore the dependence of the
clustering on the length and velocity scales involved. The paper describes a
group catalog, complete to a limiting redshift of 10,000 km/s, created by
maximizing the number of groups containing 3 or more members. A second catalog
is also presented, created by requiring a minimum density contrast of 80 to
identify groups. We identify known nearby clusters in the catalogs and contrast
the groups identified in the two catalogs. We examine and compare the
properties of the determined groups and verify that the results are consistent
with the UZC-SSRS2 and northern CfA redshift survey group catalogs. The all-sky
nature of the catalog will allow the development of a flow-field model based on
the density field inferred from the estimated cluster masses.Comment: Accepted for publication in ApJ (29 pages including 13 figures). A
version with high-resolution figures is available at
http://www.cfa.harvard.edu/~acrook/preprints
Geology of Joppa Quadrangle, Massac County, Illinois
Relief shown by contours and spot heightsIncludes location map and index to adjoining quadranglesSheet 2 includes text, cross section and stratigraphic columnIncludes bibliographical references (p. 10-11 of text
Quaternary faulting in the New Madrid seismic zone in southernmost Illinois
U.S. Geological Survey, Department of the Interior, under USGS award number 1434-95-G-2525Ope
The management of tree genetic resources and the livelihoods of rural communities in the tropics: non-timber forest products, smallholder agroforestry practices and tree commodity crops
Products and services provided by trees in forests and farmland support the needs and promote the wellbeing of hundreds of millions of people in the tropics. Value depends on managing both the diversity of tree species present in landscapes and the genetic variation within these species. The benefits from trees and their genetic resources are, however, often not well quantified because trade is frequently outside formal markets, there is a multiplicity of species and ways in which trees are used and managed, and genetic diversity within species is frequently not given proper consideration. We review here what is known about the value of trees to rural communities through considering three production categories: non-timber products harvested from trees in natural and managed forests and woodlands; the various products and services obtained from a wide range of trees planted and/or retained in smallholders’ agroforestry systems; and the commercial products harvested from cultivated tree commodity crops. Where possible, we focus on the role of intra-specific genetic variation in providing support to livelihoods, and for each of the three production categories we also consider wider conservation and sustainability issues, including the linkages between categories in terms of management. Challenges to ‘conventional wisdom’ on tree resource use, value and management – such as in the posited links between commercialisation, cultivation and conservation – are highlighted, and constraints and opportunities to maintain and enhance value are described
Mechanical properties of triaxially braided composites: Experimental and analytical results
The unnotched tensile properties of 2-D triaxial braid reinforced composites from both an experimental and an analytical viewpoint are studied. The materials are graphite fibers in an epoxy matrix. Three different reinforcing fiber architectures were considered. Specimens were cut from resin transfer molded (RTM) composite panels made from each braid. There were considerable differences in the observed elastic constants from different size strain gage and extensometer reading. Larger strain gages gave more consistent results and correlated better with the extensometer reading. Experimental strains correlated reasonably well with analytical predictions in the longitudinal, 0 degrees, fiber direction but not in the transverse direction. Tensile strength results were not always predictable even in reinforcing directions. Minor changes in braid geometry led to disproportionate strength variations. The unit cell structure of the triaxial braid was discussed with the assistance of computer analysis of the microgeometry. Photomicrographs of braid geometry were used to improve upon the computer graphics representations of unit cells. These unit cells were used to predict the elastic moduli with various degrees of sophistication. The simple and the complex analyses were generally in agreement but none adequately matched the experimental results for all the braids
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