165 research outputs found
The use of the sediment fingerprinting technique to quantify the different sediment sources entering the Whangapoua Estuary, North Island, in New Zealand
New Zealand estuaries are sites of ecological, economic, and recreational significance. Estuaries are vulnerable to the impacts of increased erosion as they act as natural sediment traps. The objectives of this study were to; 1) quantify the relative amounts of sediment entering the estuary from the native forest, exotic forest, and agricultural landscape units in the Whangapoua catchment, Coromandel Peninsula, New Zealand; 2) identify the dominant processes generating the sediment within the native forest, exotic forest, and pastoral landscape units; and 3) assess the utility of the sediment fingerprinting technique in New Zealand by comparing the results with other sediment measurement techniques. Sediment fingerprinting, which uses geochemical elements to link potential source areas to the estuary sediment, was used to identify sediment sources in the Whangapoua catchment. Three landscape units (referred to as native forest, exotic forest, and agriculture), and three erosion positions (surface, subsurface, and streambanks) were investigated. A radionuclide tracing study, a stream suspended sediment monitoring programme, and catchment modelling were undertaken to compare with the sediment fingerprinting results. An initial pilot study was undertaken which confirmed that sediment fingerprinting could distinguish sediment derived from the three landscape units and three erosion positions. In a full sampling programme, the landscape units and erosion positions in the Whangapoua catchment were each characterised by analysing 50 samples using ICP-MS to determine the concentrations of 29 elements. The elements Si, P, Se, V, U, In, and Bi were identified as forming a composite fingerprint to distinguish landscape units. The native forest landscape unit (21% of the catchment area) contributed 62% of estuary sediment, with 23% from the exotic forest (61% of the catchment area), and 15% from the agricultural landscape unit (18% of the catchment area). The elements Se, Fe, Ba, Mn, P, and Ca formed a composite fingerprint to distinguish erosion positions and showed that most of the estuary sediment was derived from subsurface (79%), followed by streambanks (13%), and then surface sources (8%). A radionuclide tracing study was undertaken and 15 samples were used to characterise each of the surface, subsurface, and streambank erosion positions. 137Cs was effective at distinguishing the surface (0-2cm) from other erosion positions, but could not distinguish the subsurface (>20cm) from the streambank sediment. The 137Cs results indicated that up to 98% of the estuary sediment was derived from subsurface and streambank sources. Stream suspended sediment monitoring was undertaken at four small subcatchment sites over a two year period. Monitoring commenced at the four sites as follows; immediately harvested exotic pines, six month post harvested pines, ten year re-growth pines, and agricultural pastures. The erosion rates were high in pines after harvesting (48 t km-2 yr -1), but dropped to 28 t km-2 yr -1 six months post harvesting and then to 2 t km-2 yr -1 ten years post harvesting. The agricultural erosion rate was calculated at 7 t km-2 yr -1. The lack of a native forest monitoring site, lack of replication, data capture problems, and inherent errors limit confidence in the stream suspended sediment monitoring results which should only be considered indicative. A stream bed sampling programme used 18 sampling points to estimate how much fine sediment was stored within the rivers and streams. Less than 4% of the annual estuary fine sediment budget was stored within the stream and river beds, indicating that sediment was efficiently conducted from the native forest landscape unit into the estuary. Two catchment models (Sediment Yield Estimator and the New Zealand Empirical Erosion Model) gave results that were contradictory to the sediment fingerprinting results as they suggested that deforested areas (such as agriculture and harvested pines) were sediment generating areas. This thesis demonstrated that the use of sediment fingerprinting in New Zealand was an effective means of quantifying various sediment sources based on landscape unit and erosion position. The current pattern of landuse within the Whangapoua catchment is appropriate in providing an economic return while minimising the levels of sediment delivery to the Whangapoua estuary
SLEPLET: Slepian Scale-Discretised Wavelets in Python
Wavelets are widely used in various disciplines to analyse signals both in
space and scale. Whilst many fields measure data on manifolds (i.e., the
sphere), often data are only observed on a partial region of the manifold.
Wavelets are a typical approach to data of this form, but the wavelet
coefficients that overlap with the boundary become contaminated and must be
removed for accurate analysis. Another approach is to estimate the region of
missing data and to use existing whole-manifold methods for analysis. However,
both approaches introduce uncertainty into any analysis. Slepian wavelets
enable one to work directly with only the data present, thus avoiding the
problems discussed above. Applications of Slepian wavelets to areas of research
measuring data on the partial sphere include gravitational/magnetic fields in
geodesy, ground-based measurements in astronomy, measurements of whole-planet
properties in planetary science, geomagnetism of the Earth, and cosmic
microwave background analyses.Comment: 4 page
SLEPLET: Slepian Scale-Discretised Wavelets in Python
Wavelets are widely used in various disciplines to analyse signals both in space and scale.
Whilst many fields measure data on manifolds (i.e., the sphere), often data are only observed
on a partial region of the manifold. Wavelets are a typical approach to data of this form, but
the wavelet coefficients that overlap with the boundary become contaminated and must be
removed for accurate analysis. Another approach is to estimate the region of missing data
and to use existing whole-manifold methods for analysis. However, both approaches introduce
uncertainty into any analysis. Slepian wavelets enable one to work directly with only the data
present, thus avoiding the problems discussed above. Applications of Slepian wavelets to
areas of research measuring data on the partial sphere include gravitational/magnetic fields in
geodesy, ground-based measurements in astronomy, measurements of whole-planet properties
in planetary science, geomagnetism of the Earth, and cosmic microwave background analyses
Slepian Wavelets for the Analysis of Incomplete Data on Manifolds
Many fields in science and engineering measure data that inherently live on non-Euclidean geometries, such as the sphere. Techniques developed in the Euclidean setting must be extended to other geometries. Due to recent interest in geometric deep learning, analogues of Euclidean techniques must also handle general manifolds or graphs. Often, data are only observed over partial regions of manifolds, and thus standard whole-manifold techniques may not yield accurate predictions. In this thesis, a new wavelet basis is designed for datasets like these.
Although many definitions of spherical convolutions exist, none fully emulate the Euclidean definition. A novel spherical convolution is developed, designed to tackle the shortcomings of existing methods. The so-called sifting convolution exploits the sifting property of the Dirac delta and follows by the inner product of a function with the translated version of another. This translation operator is analogous to the Euclidean translation in harmonic space and exhibits some useful properties. In particular, the sifting convolution supports directional kernels; has an output that remains on the sphere; and is efficient to compute. The convolution is entirely generic and thus may be used with any set of basis functions. An application of the sifting convolution with a topographic map of the Earth demonstrates that it supports directional kernels to perform anisotropic filtering.
Slepian wavelets are built upon the eigenfunctions of the Slepian concentration problem of the manifold - a set of bandlimited functions which are maximally concentrated within a given region. Wavelets are constructed through a tiling of the Slepian harmonic line by leveraging the existing scale-discretised framework. A straightforward denoising formalism demonstrates a boost in signal-to-noise for both a spherical and general manifold example. Whilst these wavelets were inspired by spherical datasets, like in cosmology, the wavelet construction may be utilised for manifold or graph data
Sifting Convolution on the Sphere
A novel spherical convolution is defined through the sifting property of the
Dirac delta on the sphere. The so-called sifting convolution is defined by the
inner product of one function with a translated version of another, but with
the adoption of an alternative translation operator on the sphere. This
translation operator follows by analogy with the Euclidean translation when
viewed in harmonic space. The sifting convolution satisfies a variety of
desirable properties that are lacking in alternate definitions, namely: it
supports directional kernels; it has an output which remains on the sphere; and
is efficient to compute. An illustration of the sifting convolution on a
topographic map of the Earth demonstrates that it supports directional kernels
to perform anisotropic filtering, while its output remains on the sphere.Comment: 5 pages, 3 figure
List of Marian Books in the St. Barbara Province, Order of Friars Minor
A list of books held by 35 Franciscan friary libraries in Arizona, California, New Mexico, Oregon, and Washington, organized by author and coded to indicate holding locations. Colophon states the list was completed by Patrick Roddy, O.F.M., libarian at Old Mission Santa Barbara. Reproduced typescript
Money, Death, and Agency in Catholic Ireland, 1850–1921
Between the end of the Great Famine and the end of the union with Britain, the Irish Catholic Church was almost exclusively funded by ordinary lay people. This article examines the financial relationship between clergy and laity, focusing on payments related to death. In doing so, it argues three main points. First, it suggests that previous conceptions of lay people coerced into giving their money to the church are too simplistic and deny the complex agency of the people of many social classes who gave the money. Second, it argues that using the financial transactions of ordinary people gives historians a much-needed methodology for recovering lives about which the archives are otherwise silent. Third, it posits that the mediation of faith through money, specifically, must be added to the growing body of work on "material religion.
Providing real-time assistance in disaster relief by leveraging crowdsourcing power
Crowdsourcing platforms for disaster management have drawn a lot of attention in recent years due to their efficiency in disaster relief tasks, especially for disaster data collection and analysis. Although the on-site rescue staff can largely benefit from these crowdsourcing data, due to the rapidly evolving situation at the disaster site, they usually encounter various difficulties and have requests, which need to be resolved in a short time. In this paper, aiming at efficiently harnessing crowdsourcing power to provide those on-site rescue staff with real-time remote assistance, we design and develop a crowdsourcing disaster support platform by considering three unique features, viz., selecting and notifying relevant off-site users for individual request according to their expertise; providing collaborative working functionalities to off-site users; improving answer credibility via “crowd voting.” To evaluate the platform, we conducted a series of experiments with three-round user trials and also a System Usability Scale survey after each trial. The results show that the platform can effectively support on-site rescue staff by leveraging crowdsourcing power and achieve good usability
A computerised test of perceptual ability for learning endoscopic and laparoscopic surgery and other image guided procedures: Score norms for PicSOr
Background: The aptitude to infer the shape of 3-D structures, such as internal organs from 2-D monitor displays, in image guided endoscopic and laparoscopic procedures varies. We sought both to validate a computer-generated task Pictorial Surface Orientation (PicSOr), which assesses this aptitude, and to identify norm referenced scores. Methods: 400 subjects (339 surgeons and 61 controls) completed the PicSOr test. 50 subjects completed it again one year afterwards. Results: Complete data was available on 396 of 400 subjects (99%). PicSOr demonstrated high test and re-test reliability (r = 0.807, p < 0.000). Surgeons performed better than controls' (surgeons = 0.874 V controls = 0.747, p < 0.000). Some surgeons (n = 22–5.5%) performed atypically on the test. Conclusions: PicSOr has population distribution scores that are negatively skewed. PicSOr quantitatively characterises an aptitude strongly correlated to the learning and performance of image guided medical tasks. Most can do the PicSOr task almost perfectly, but a substantial minority do so atypically, and this is probably relevant to learning and performing endoscopic tasks
Ion-neutral Coupling During Deep Solar Minimum
The equatorial ionosphere under conditions of deep solar minimum exhibits structuring due to tidal forces. Data from instruments carried by the Communication Navigation Outage Forecasting System (CNOFS) which was launched in April 2008 have been analyzed for the first 2 years following launch. The Planar Langmuir Probe (PLP), Ion Velocity Meter (IVM) and Vector Electric Field Investigation (VEFI) all detect periodic structures during the 20082010 period which appear to be tides. However when the tidal features detected by these instruments are compared, there are distinctive and significant differences between the observations. Tides in neutral densities measured by the Gravity Recovery and Climate Experiment (GRACE) satellite were also observed during June 2008. In addition, Broad Plasma Decreases (BPDs) appear as a deep absolute minimum in the plasma and neutral density tidal pattern. These are co-located with regions of large downward-directed ion meridional velocities and minima in the zonal drifts, all on the nightside. The region in which BPDs occur coincides with a peak in occurrence rate of dawn depletions in plasma density observed on the Defense Meterological Satellite Program (DMSP) spacecraft, as well as a minimum in radiance detected by UV imagers on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and IMAGE satellite
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