1,011 research outputs found
Stability of silicate minerals Final report, 1 Feb. 1966 - 1 Jun. 1968
Stability of silicate minerals as function of pressure, temperature, and oxygen fugacit
Airborne laser scanning of natural forests in New Zealand reveals the influences of wind on forest carbon
Abstract
Background
Forests are a key component of the global carbon cycle, and research is needed
into the effects of human-driven and natural processes on their carbon pools.
Airborne laser scanning (ALS) produces detailed 3D maps of forest canopy structure
from which aboveground carbon density can be estimated. Working with a ALS dataset
collected over the 8049-km2 Wellington Region of New
Zealand we create maps of indigenous forest carbon and evaluate the influence of
wind by examining how carbon storage varies with aspect. Storms flowing from the
west are a common cause of disturbance in this region, and we hypothesised that
west-facing forests exposed to these winds would be shorter than those in
sheltered east-facing sites.
Methods
The aboveground carbon density of 31 forest inventory plots located within the
ALS survey region were used to develop estimation models relating carbon density
to ALS information. Power-law models using rasters of top-of-the-canopy height
were compared with models using tree-level information extracted from the ALS
dataset. A forest carbon map with spatial resolution of 25 m was generated from
ALS maps of forest height and the estimation models. The map was used to evaluate
the influences of wind on forests.
Results
Power-law models were slightly less accurate than tree-centric models (RMSE
35% vs 32%) but were selected for map generation for computational efficiency. The
carbon map comprised 4.5 million natural forest pixels within which canopy height
had been measured by ALS, providing an unprecedented dataset with which to examine
drivers of carbon density. Forests facing in the direction of westerly storms
stored less carbon, as hypothesised. They had much greater above-ground carbon
density for a given height than any of 14 tropical forests previously analysed by
the same approach, and had exceptionally high basal areas for their height. We
speculate that strong winds have kept forests short without impeding basal area
growth.
Conclusion
Simple estimation models based on top-of-the canopy height are almost as
accurate as state-of-the-art tree-centric approaches, which require more computing
power. High-resolution carbon maps produced by ALS provide powerful datasets for
evaluating the environmental drivers of forest structure, such as wind.
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A brief description of geological and geophysical exploration of the Marysville geothermal area
Extensive geological and geophysical surveys were carried out at the Marysville geothermal area during 1973 and 1974. The area has high heat flow (up to microcalories per square centimeter-second, a negative gravity anomaly, high electrical resistivity, low seismic ground noise, and nearby microseismic activity. Significant magnetic and infrared anomalies are not associated with the geothermal area. The geothermal anomaly occupies the axial portion of a dome in Precambrian sedimentary rocks intruded by Cretaceous and Cenozoic granitic rocks. The results from a 2.4-km-deep test well indicate that the cause of the geothermal anomaly is hydrothermal convection in a Cenozoic intrusive. A maximum temperature of 95 C was measured at a depth of 500 m in the test well
Concordance between missed days of hepatitis B virus anti-viral therapy and virological breakthrough
Aggressive pituitary adenomas occurring in young patients in a large Polynesian kindred with a germline R271W mutation in the AIP gene.
peer reviewedOBJECTIVE: Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) were recently shown to confer a pituitary adenoma predisposition in patients with familial isolated pituitary adenomas (FIPA). We report a large Samoan FIPA kindred from Australia/New Zealand with an R271W mutation that was associated with aggressive pituitary tumors. DESIGN AND METHODS: Case series with germline screening of AIP and haplotype analyses among R271W families. RESULTS: This previously unreported kindred consisted of three affected individuals that either presented with or had first symptoms of a pituitary macroadenoma in late childhood or adolescence. The index case, a 15-year-old male with incipient gigantism and his maternal aunt, had somatotropinomas, and the maternal uncle of the index case had a prolactinoma. All tumors were large (15, 40, and 60 mm maximum diameter) and two required transcranial surgery and radiotherapy. All three affected subjects and ten other unaffected relatives were found to be positive for a germline R271W AIP mutation. Comparison of the single nucleotide polymorphism patterns among this family and two previously reported European FIPA families with the same R271W mutation demonstrated no common ancestry. CONCLUSIONS: This kindred exemplifies the aggressive features of pituitary adenomas associated with AIP mutations, while genetic analyses among three R271W FIPA families indicate that R271W represents a mutational hotspot that should be studied further in functional studies
Profiling the Dead: Generating Microsatellite Data from Fossil Bones of Extinct Megafauna—Protocols, Problems, and Prospects
We present the first set of microsatellite markers developed exclusively for an extinct taxon. Microsatellite data have been analysed in thousands of genetic studies on extant species but the technology can be problematic when applied to low copy number (LCN) DNA. It is therefore rarely used on substrates more than a few decades old. Now, with the primers and protocols presented here, microsatellite markers are available to study the extinct New Zealand moa (Aves: Dinornithiformes) and, as with single nucleotide polymorphism (SNP) technology, the markers represent a means bywhich the field of ancient DNA can (preservation allowing) move on from its reliance on mitochondrial DNA. Candidate markers were identified using high throughput sequencing technology (GS-FLX) on DNA extracted from fossil moa bone and eggshell. From the ‘shotgun’ reads, .60 primer pairs were designed and tested on DNA from bones of the South Island giant moa (Dinornis robustus). Six polymorphic loci were characterised and used to assess measures of genetic diversity. Because of low template numbers, typical of ancient DNA, allelic dropout was observed in 36–70% of the PCR reactions at each microsatellite marker. However, a comprehensive survey of allelic dropout, combined with supporting quantitative PCR data, allowed us to establish a set of criteria that maximised data fidelity. Finally, we demonstrated the viability of the primers and the protocols, by compiling a full Dinornis microsatellite dataset representing fossils of c. 600–5000 years of age. A multi-locus genotype was obtained from 74 individuals (84% success rate), and the data showed no signs of being compromised by allelic dropout. The methodology presented here provides a framework by which to generate and evaluate microsatellite data from samples of much greater antiquity than attempted before, and opens new opportunities for ancient DNA research
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