494 research outputs found
Future Prospects: Deep Imaging of Galaxy Outskirts using Telescopes Large and Small
The Universe is almost totally unexplored at low surface brightness levels.
In spite of great progress in the construction of large telescopes and
improvements in the sensitivity of detectors, the limiting surface brightness
of imaging observations has remained static for about forty years. Recent
technical advances have at last begun to erode the barriers preventing
progress. In this Chapter we describe the technical challenges to low surface
brightness imaging, describe some solutions, and highlight some relevant
observations that have been undertaken recently with both large and small
telescopes. Our main focus will be on discoveries made with the Dragonfly
Telephoto Array (Dragonfly), which is a new telescope concept designed to probe
the Universe down to hitherto unprecedented low surface brightness levels. We
conclude by arguing that these discoveries are probably only scratching the
surface of interesting phenomena that are observable when the Universe is
explored at low surface brightness levels.Comment: 27 pages, 10 figures, Invited review, Book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
Visualization of Active Faulting using 3-D GPR Data Recorded Across the Alpine Fault, New Zealand
Three-dimensional (3-D) GPR data were acquired
across braided river sediments cut by the Alpine Fault at Calf
Paddock, New Zealand. We used 100 MHz antennas to obtain
images of the subsurface to a depth of 15 m. Cross-sections and
depth-converted time slices selected from the migrated data volume
show both the structural contrast generated by recent offsets
of the fault and the variable orientation of the dipping structures
within the braided river deposits. A trace-correlation technique is
used to generate dip and dip-direction attribute maps that allow us
to visualize the 3-D orientation of the dipping structures. The
attribute maps reveal at least 3 different reflection patterns and the
presence of minor faulting away from the main fault. A correlation-
based migration technique applied to a 2-D GPR profile resulted
in the successful identification of the main fault and subsidiary
faults at distances up to 50 m from the main fault
Prime agricultural land monitoring and assessment component of the California Integrated Remote Sensing System
The use of digital LANDSAT techniques for monitoring agricultural land use conversions was studied. Two study areas were investigated: one in Ventura County and the other in Fresno County (California). Ventura test site investigations included the use of three dates of LANDSAT data to improve classification performance beyond that previously obtained using single data techniques. The 9% improvement is considered highly significant. Also developed and demonstrated using Ventura County data is an automated cluster labeling procedure, considered a useful example of vertical data integration. Fresno County results for a single data LANDSAT classification paralleled those found in Ventura, demonstrating that the urban/rural fringe zone of most interest is a difficult environment to classify using LANDSAT data. A general raster to vector conversion program was developed to allow LANDSAT classification products to be transferred to an operational county level geographic information system in Fresno
Habitat Characteristics of Eastern Wild Turkey Nest and Ground-roost Sites in 2 Longleaf Pine Forests
Managing and restoring longleaf pine forests throughout the Southeast is a conservation priority. Prescribed fire is an integral part of these activities, as it is the primary means of controlling hardwood encroachment and maintaining native groundcover. Nest site and preflight brood groundroost site selection of eastern wild turkeys (Meleagris gallopavo silvestris) has not been well studied in longleaf pine systems. Therefore, we determined habitat characteristics associated with wild turkey nests and ground-roosts in 2 longleaf pine forests in southwestern Georgia. We radio-tagged 45 female turkeys and evaluated habitat characteristics associated with 84 nests and 51 ground-roosts during the 2011–2013 nesting seasons. Nests were located farther from mature pine and mature pine-hardwood stands and closer to shrub/scrub habitats than expected. Nests were also negatively associated with percent canopy closure and positively associated with percent woody ground cover and vegetation height. Ground-roosts were closer to mature pine-hardwood stands and open water than were random sites. We suggest that management of longleaf pine forests should focus on maintaining open-canopied forests with adequate understory vegetation to serve as nesting and brood-rearing cover. Our findings suggest that frequent prescribed fire (≤ 2 years), when the management goal is to optimize restoration of longleaf ecosystems, is conducive to maintaining wild turkey populations
Higher masseter muscle mass in grazing than in browsing ruminants
Using cranioskeletal measurements, several studies have generated evidence that grazing ruminants have a more pronounced mastication apparatus, in terms of muscle insertion areas and protuberances, than browsing ruminants, with the resulting hypothesis that grazers should have larger, heavier chewing muscles than browsers. However, the only investigation of this so far [Axmacher and Hofmann (J Zool 215:463–473, 1988)] did not find differences between ruminant feeding types in the masseter muscle mass of 22 species. Here, we expand the dataset to 48 ruminant species. Regardless of phylogenetic control in the statistical treatment, there was a significant positive correlation of body mass and masseter mass, and also a significant association between percent grass in the natural diet and masseter mass. The results support the concept that ruminant species that ingest more grass have relatively larger masseter muscles, possibly indicating an increased requirement to overcome the resistance of grass forage. The comparative chewing resistance of different forage classes may represent a rewarding field of ecophysiological research
Active learning across disciplines : opportunities to develop employability skills and leadership potential in undergraduate students. A student and staff perspective
Working effectively within multidisciplinary
teams is an important employability skill
common in postgraduate working life, but
opportunities to develop this are limited in
many undergraduate taught programmes. The
projects reported here offered twelve level 5
undergraduate students from a range of
science disciplines the opportunity to work with
each other and staff on a specific research
question. This paper explores the experience
of cross-disciplinary research from both the
student and staff research partners’
perspectives. In particular the employability
skills gained from such partnership working,
the potential for developing and demonstrating
leadership skills, and the benefits and
disadvantages are discussed
Recommended from our members
Global diversity of the Brachypodium species complex as a resource for genome-wide association studies demonstrated for agronomic traits in response to climate
The development of model systems requires a detailed assessment of standing genetic variation across natural populations. The Brachypodium species complex has been promoted as a plant model for grass genomics with translation to small grain and biomass crops. To capture the genetic diversity within this species complex, thousands of Brachypodium accessions from around the globe were collected and genotyped by sequencing. Overall, 1897 samples were classified into two diploid or allopolyploid species, and then further grouped into distinct inbred genotypes. A core set of diverse B. distachyon diploid lines was selected for whole genome sequencing and high resolution phenotyping. Genome-wide association studies across simulated seasonal environments was used to identify candidate genes and pathways tied to key life history and agronomic traits under current and future climatic conditions. A total of 8, 22, and 47 QTL were identified for flowering time, early vigor, and energy traits, respectively. The results highlight the genomic structure of the Brachypodium species complex, and the diploid lines provided a resource that allows complex trait dissection within this grass model species.We are grateful for
funding and support from the Australian Research Council
Centre of Excellence in Plant Energy Biology (CE140100008).
Australian Plant Phenomics Facility is supported under the
National Collaborative Research Infrastructure Strategy of the
Australian Government. The research was undertaken with
the assistance of resources from the National Computational
Infrastructure (NCI), which is supported by the Australian
Government
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