7,551 research outputs found
Macrofossils and pollen representing forests of the pre-Taupo volcanic eruption (c. 1850 yr BP) era at Pureora and Benneydale, central North Island, New Zealand.
Micro- and macrofossil data from the remains of forests overwhelmed and buried at Pureora and Benneydale during the Taupo eruption (c. 1850 conventional radiocarbon yr BP) were compared. Classification of relative abundance data separated the techniques, rather than the locations, because the two primary clusters comprised pollen and litter/wood. This indicates that the pollen:litter/wood within-site comparisons (Pureora and Benneydale are 20 km apart) are not reliable. Plant macrofossils represented mainly local vegetation, while pollen assemblages represented a combination of local and regional vegetation. However, using ranked abundance and presence/absence data, both macrofossils and pollen at Pureora and Benneydale indicated conifer/broadleaved forest, of similar forest type and species composition at each site. This suggests that the forests destroyed by the eruption were typical of mid-altitude west Taupo forests, and that either data set (pollen or macrofossils) would have been adequate for regional forest interpretation.
The representation of c. 1850 yr BP pollen from the known buried forest taxa was generally consistent with trends determined by modern comparisons between pollen and their source vegetation, but with a few exceptions.
A pollen profile from between the Mamaku Tephra (c. 7250 yr BP) and the Taupo Ignimbrite indicated that the Benneydale forest had been markedly different in species dominance compared with the forest that was destroyed during the Taupo eruption. These differences probably reflect changes in drainage, and improvements in climate and/or soil fertility over the middle Holocene
Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle
A suggested solution to the dark energy problem is the void model, where
accelerated expansion is replaced by Hubble-scale inhomogeneity. In these
models, density perturbations grow on a radially inhomogeneous background. This
large scale inhomogeneity distorts the spherical Baryon Acoustic Oscillation
feature into an ellipsoid which implies that the bump in the galaxy correlation
function occurs at different scales in the radial and transverse correlation
functions. We compute these for the first time, under the approximation that
curvature gradients do not couple the scalar modes to vector and tensor modes.
The radial and transverse correlation functions are very different from those
of the concordance model, even when the models have the same average BAO scale.
This implies that if void models are fine-tuned to satisfy average BAO data,
there is enough extra information in the correlation functions to distinguish a
void model from the concordance model. We expect these new features to remain
when the full perturbation equations are solved, which means that the radial
and transverse galaxy correlation functions can be used as a powerful test of
the Copernican Principle.Comment: 12 pages, 8 figures, matches published versio
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Model granularity and related concepts
Models are integral to engineering design and basis for many decisions. Therefore, it is necessary to comprehend how a modelâs properties might influence its behaviour. Model granularity is an important property but has so far only received limited attention. The terminology used to describe granularity and related phenomena varies and pertinent concepts are distributed across communities. This article positions granularity in the theoretical background of models, collects formal definitions for relevant terms from a range of communities and discusses the implications for engineering design
ROC and the bounds on tail probabilities via theorems of Dubins and F. Riesz
For independent and in the inequality , we give sharp
lower bounds for unimodal distributions having finite variance, and sharp upper
bounds assuming symmetric densities bounded by a finite constant. The lower
bounds depend on a result of Dubins about extreme points and the upper bounds
depend on a symmetric rearrangement theorem of F. Riesz. The inequality was
motivated by medical imaging: find bounds on the area under the Receiver
Operating Characteristic curve (ROC).Comment: Published in at http://dx.doi.org/10.1214/08-AAP536 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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Towards a change process planning tool
The relationship between a product and its design process is generally complex and not fully understood. When modifying a product, industry still rarely considers the implementation process and its consequences for other design activities in the company, which is hard to assess with conventional planning methods. Although change processes are highly constrained, product and process constraints are not usually considered together or traded off against each other when planning the change. Inadequate assessment and planning of the change implementation process can lead to costly knock-on effects across the product and the design process. This paper argues for a combination of change and process research and discusses requirements for a change process planning tool. It proposes a system for the analysis of the impact of change on the product as well as other company activities. Then, a more informed selection between change alternatives is possible
Vegetation restoration plan, New Plymouth Fitzroy to Bell Block coastal walkway extension
In 1999, the New Plymouth District Council began construction of its award winning coastal walkway. Along with providing an area for recreation, this new walk and cycle path serves as an alternate route for commuting along the city away from arterial roads. The New Plymouth District Council is in the process of extending this walkway a further three kilometres from Fitzroy Motor Camp to Ellesmere Avenue, Bell Block. This will encompass Peringa Park, Hickford Park and the Mangati Walkway, with completion expected by mid 2010. As part of this $4.2 million project, the District Council aims to restore the surrounding native duneland vegetation. The Centre for Biodiversity and Ecology Research (University of Waikato) was contracted by the New Plymouth District Council to provide a vegetation restoration plan for the Fitzroy to Bell Block section of the coastal walkway. This report considers the current vegetation of this three km section of the walkway, based on a rapid qualitative assessment undertaken in June, 2010. The target ecosytems Spinifex sandfield, flax-taupata shrubland and coastal forest vegetation types once dominant in the area are described in detail. Restoration recommendations are included to assist in the recreation of these ecosystems, including planting zones, weed control strategies and ongoing monitoring objectives
Synthesis and use of a stable aminal derived from TsDPEN in asymmetric organocatalysis
A stable aminal formed stereoselectively from (R,R)-N-tosyl-1,2-diphenyl-1,2-ethylenediamine (TsDPEN) is capable of asymmetric organocatalysis of Diels-Alder and alpha-amination reactions of aldehydes
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