7,087 research outputs found
The Siricidae (Hymenoptera: Symphyta) of Florida
The six species of Siricidae (Hymenoptera: Symphyta) occurring in Florida and one species of regulatory concern introduced to North America are reviewed. Included are diagnoses of Eriotremex formosanus (Matsumura), Sirex areolatus (Cresson), Sirex nigricornis Fabricius, Tremex columba (Linnaeus), Urocerus cressoni Norton, Urocerus taxodii (Ashmead) and Sirex noctilio (Fabricius). A key to species, photographs of morphological features, biological notes and distribution data are provided. For the species T. columba, S. nigricornis, U. taxodii, and U. cressoni, a total of eight new state records are presented
Probing the Interstellar Dust towards the Galactic Centre: Dust Scattering Halo around AX J1745.6-2901
AX J1745.6-2901 is an X-ray binary located at only 1.45 arcmin from Sgr A*,
showcasing a strong X-ray dust scattering halo. We combine Chandra and
XMM-Newton observations to study the halo around this X-ray binary. Our study
shows two major thick dust layers along the line of sight (LOS) towards AX
J1745.6-2901. The LOS position and of these two layers depend on the
dust grain models with different grain size distribution and abundances. But
for all the 19 dust grain models considered, dust Layer-1 is consistently found
to be within a fractional distance of 0.11 (mean value: 0.05) to AX
J1745.6-2901 and contains only (19-34)% (mean value: 26%) of the total LOS
dust. The remaining dust is contained in Layer-2, which is distributed from the
Earth up to a mean fractional distance of 0.64. A significant separation
between the two layers is found for all the dust grain models, with a mean
fractional distance of 0.31. Besides, an extended wing component is discovered
in the halo, which implies a higher fraction of dust grains with typical sizes
590 \AA\ than considered in current dust grain models. Assuming AX
J1745.6-2901 is 8 kpc away, dust Layer-2 would be located in the Galactic disk
several kpc away from the Galactic Centre (GC). The dust scattering halo biases
the observed spectrum of AX J1745.6-2901 severely in both spectral shape and
flux, and also introduces a strong dependence on the size of the instrumental
point spread function and the source extraction region. We build Xspec models
to account for this spectral bias, which allow us to recover the intrinsic
spectrum of AX J1745.6-2901 free from dust scattering opacity. If dust Layer-2
also intervenes along the LOS to Sgr A* and other nearby GC sources, a
significant spectral correction for the dust scattering opacity would be
necessary for all these GC sources.Comment: 20 pages, published by MNRAS; revised values in Table-1 and Table-B
The Impact of Accurate Extinction Measurements for X-ray Spectral Models
Interstellar extinction includes both absorption and scattering of photons
from interstellar gas and dust grains, and it has the effect of altering a
source's spectrum and its total observed intensity. However, while multiple
absorption models exist, there are no useful scattering models in standard
X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created
by scattering from dust grains, are detected around even moderately absorbed
sources and the impact on an observed source spectrum can be significant, if
modest, compared to direct absorption. By convolving the scattering cross
section with dust models, we have created a spectral model as a function of
energy, type of dust, and extraction region that can be used with models of
direct absorption. This will ensure the extinction model is consistent and
enable direct connections to be made between a source's X-ray spectral fits and
its UV/optical extinction.Comment: 8 pages, 4 figure
The Sustainable Sites Initiative As It Applies To Existing Parks In Logan Utah
The Intermountain West of the United States consists of a variety of climates and landscapes. Despite their diversity, all of these regions face similar issues, such as water shortage, lack of biodiversity, invasion of non-native plant species, land development, and population growth. The pursuit of sustainability has become imperative in order to meet the needs of the present, while simultaneously safeguarding the ability of future generations to meet their own needs. Many influential landscape architects have advocated for sustainable design; namely, Frederick Law Olmsted, Ian McHarg, and Laurie Olin. However, sustainability is used too often as a generic buzzword, diminishing its power and making sustainable design difficult to achieve. The Sustainable SITES Initiative (SSI) gives landscape designers tangible guidelines for sustainable landscape design through “a rating system that guides, evaluates, and certifies a project’s sustainability in the planning, design, construction and management of landscapes and other outdoor spaces (SITES).” Owned by the U.S. Green Building Council, it can be a great tool for sustainable advocates; however, its limited scope and certification can make success difficult to achieve when the SITES requirements are strictly observed.
The purpose of this study is to apply the SITES v2 Rating System scorecard to three existing parks in Logan, Utah. Though the system does not allow retroactive certification, this process will reveal a unique perspective regarding the scoring system’s limitations and the parks’ limited sustainable features. The scorecards will be used to recommend improvements to these parks, which will again reveal the disparity between certification and realistic improvements to existing public spaces
Black Holes and Vacuum Cleaners: Using Metaphor, Relevance, and Inquiry in Labels for Space Images
This study extended research on the development of explanatory labels for
astronomical images for the non-expert lay public. The research questions
addressed how labels with leading questions/metaphors and relevance to everyday
life affect comprehension of the intended message for deep space images, the
desire to learn more, and the aesthetic appreciation of images. Participants
were a convenience sample of 1,921 respondents solicited from a variety of
websites and through social media who completed an online survey that used four
high-resolution images as stimuli: Sagittarius A*, Solar Flare, Cassiopeia A,
and the Pinwheel Galaxy (M101). Participants were randomly assigned initially
to 1 of 3 label conditions: the standard label originally written for the
image, a label with a leading question containing a metaphor related to the
information for the image, or a label that contained a fact about the image
relevant to everyday life. Participants were randomly assigned to 1 image and
compared all labels for that image. Open-ended items at various points asked
participants to pose questions to a hypothetical astronomer. Main findings were
that the relevance condition was significantly more likely to increase wanting
to learn more; the original label was most likely to increase overall
appreciation; and, smart phone users were more likely to want to learn more and
report increased levels of appreciation. Results are discussed in terms of the
need to examine individual viewer characteristics and goals in creating
different labels for different audiences.Comment: 50 pages, 7 tables, 2 figures, accepted by the journal "Psychology of
Aesthetics, Creativity, and the Arts
The Chandra X-ray Observatory: An Astronomical Facility Available to the World
The Chandra X-ray observatory, one of NASA's "Great Observatories," provides high angular and spectral resolution X-ray data which is freely available to all. In this review I describe the instruments on chandra along with their current calibration, as well as the chandra proposal system, the freely-available Chandra analysis software package CIAO, and the Chandra archive. As Chandra is in its 6th year of operation, the archive already contains calibrated observations of a large range of X-ray sources. The Chandra X-ray Center is committed to assisting astronomers from any country who wish to use data from the archive or propose for observation
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