Implementation of novel polygon-based obfuscation methods to improve privacy of agricultural data

Geoprivacy protection is a significant concern when sharing data. To support sustainable land management by leveraging existing agricultural data, research is needed to identify how the polygon nature of static field parcels can be obfuscated to allow data sharing among individuals and organizations. In this study, five adaptive polygon-based obfuscation methods including PN*Rand, PDonut-k, PDensity-k, PAHilb, and PDonut_AHilb methods were developed and applied on the Irish Nutrient Management Planning Online (NMP Online) agricultural dataset. The polygon-based obfuscation methods introduced in this study were designed with the consideration of properties of spatial polygon objects including the spatial coordinates, shape and size of the polygon, topology, and spatial relationship between adjacent polygons that can be used to identify real-world objects. These methods were developed to guarantee that there is no false-identification and non-unique obfuscation which is important for static polygon objects in terms of accuracy and privacy protection. Qualitative approaches were developed to identify the optimal values of inner and outer radii of donut shape based on k-anonymity satisfaction and subsequently obtain the optimal value of k-anonymity. Several evaluation methods were implemented to compare the methods performance. Density-based methods particularly PDonut-AHilb provide the best trade-off between field parcel confidentiality and spatial pattern preservation and should be considered for researchers and practitioners obfuscating polygon data.     

A modeling framework for the design of collector wells

We present results of a design study performed for the Saylorville Wellfield in Iowa, which is owned and operated by the Des Moines Water Works. The purpose of this study was to estimate wellfield capacity and provide a preliminary design for two radial collector wells to be constructed in the outwash aquifer along the Des Moines River near Saylorville, Iowa. After a field investigation to characterize the aquifer, regional two-dimensional and local three-dimensional, steady-state groundwater flow modeling was performed to locate and design the wells. This modeling was the foundation for design recommendations based on the relative performance of 12 collector well designs with varying lateral numbers, elevations, screen lengths, and orientations. For each site, alternate designs were evaluated based on model estimates of the capacity, the percent of surface water captured, and the production per unit length of screen. Many of our results are consistent with current design practices based on experience and intuition, but our methods allow for a quantitative approach for comparing alternate designs. Although the results are site-specific, the framework for evaluating the hydraulic design of the Saylorville radial collector wells is broadly applicable and could be used at other riverbank filtration sites. In addition, many of the conclusions from this design study may apply at other sites where construction of radial collector wells is being considered.     

Application of new thermodynamic data to grossular phase relations

Recent low temperature, adiabatic calorimetric heat capacity measurements for grossular have been combined with DSC measurements to give entropies up to 1000 K. In conjunction with enthalpy of solution values for grossular, these data have yielded H _f ^o (298.15K) and G _f ^o (298.15K) values of –1583.2 ± 3.5 and –1496.74 ± 3.7 kcal mol^–1 respectively. For 15 reactions in the CaO-Al₂O₃-SiO₂-H₂O system, thermodynamically calculated P-T curves have been compared with experimental reversals and have shown good agreement in most cases. Calculations indicate that gehlenite is probably totally disordered. Estimates of zoisite and lawsonite entropies are consistent with the phase equilibrium and grossular data, but estimates of the entropies of pyrope and andradite show large discrepancies when compared with experimental reversals.Contribution no. 600 from the Mineralogical Laboratory, The Department of Geology and Mineralogy, The University of Michigan, Ann Arbor, Michigan 48109, USA     

Stereotypical Constructions of the Maori ‘Race’ in the Media1

Since the colonisation of Aotearoa / New Zealand by Pakeha, Maori have been stereotypically imagined as the Black Other. One of the principal mechanisms for the continued perpetuation of this racialised discourse is the representation of ‘race’ through stereotypes in the media. ‘New’ cultural geography provides a theoretical foundation to interrogate stereotypical (re)formations of Maori identity. I conclude that the use of the stereotype in the (re)formation of Maori identity further demarcates and constrains Maori within the perennial position of the Black Other. Only through a retheorisation of difference (which moves beyond the construction of the Maori ‘race’ through stereotypes), can the impact of racialisation be effectively resisted.     

The extrapolation of elastic moduli to high pressure and temperature

The elastic constants of a crystal under stress, defined as the second derivative of the crystal free energy with respect to strain, require a correction related to the static pressure at non-zero pressures. The corrections required for the elastic constants calculated by the free energy minimisation code PARAPOCS are described and tested by comparison with the elastic constants calculated numerically by applying small stresses in the appropriate orientations to simulated crystals of fluorite, forsterite, α-quartz and albite. The corrected elastic constants are then used to investigate the extrapolation of the bulk and shear moduli (and hence also the seismic wave velocities V _p and V _s) of β-spinel and forsterite to upper mantle pressures. A Murnaghan equation, thirdorder Eulerian finite strain equation, second order polynomial equation and a logistic equation were all fitted to the simulated bulk and shear moduli between 0 and 3 GPa pressure. The parameters derived for these equations are used to extrapolate the bulk and shear moduli to 14 GPa and the results are compared to the simulated high pressure moduli. Over this pressure range, the second order polynomial provides the best extrapolation of the bulk modulus, but the use of the logistic equation results in the best extrapolation of the shear modulus.     

Stability of phlogopite-quartz and sanidine-quartz: A model for melting in the lower crust

The melting of phlogopite-quartz and sanidine-quartz under vapor-absent conditions and in the presence of H₂O-CO₂ vapor have been determined from 5–20 kbar. In the lower crust (P=6–10 kbar), phlogopite + quartz melts incongruently to enstatite + liquid at temperatures as low as 710° C in the presence of H₂O. When the activity of water is sufficiently reduced by addition of CO₂, phlogopite + quartz undergoes a dehydration reaction to enstatite + sanidine + vapor, for example at 790±10° C, 5 kbar, with \(X_{H_2 O}^V\) =0.35. In the absence of vapor, phlogopite + quartz is stable up to a maximum temperature of 900° C in the crust; at higher temperatures this assemblage melts incongruently to enstatite + sanidine + liquid. The melting of sanidine-quartz in the presence of H₂O-CO₂ vapor shows marked topological differences from melting in the system albite-H₂O-CO₂, and as a result, apparent activity coefficients for water calculated from sanidine-quartz H₂O-CO₂ are less than those calculated from albite-H₂O-CO₂ by up to a factor of five. These data shed light on anatexis in the lower crust, but uncertainties related to ordering of Al and Si in natural and synthetic micas forestall a more rigorous analysis. Nevertheless, maximum temperatures for some granulite terranes can be established.     

Measurements of the HONO photodissociation constant

Measurements of the photodissociation constant for nitrous acid (j _HONO) were made at an urban site in Toronto, Canada, during the months of May–July 2005, using an optically thin actinometer. Operating details of the j _HONO monitor are reported, along with laboratory tests. Measurements of j _HONO were obtained for solar zenith angles ranging from 20–75^∘, under clear and cloudy skies. Maximum error estimates on j _HONO under clear skies range from 11% at sunrise, to 4% at solar noon, with a minimum detection limit of 5.7 × 10⁻⁴/sec for our actinometer. Measured clear-sky values of j _HONO were compared with values calculated by a four-stream discrete ordinate radiative transfer (RT) model (ACD TUV version 4.1), and were found to be within better than 10% agreement for solar zenith angles < 65^∘. For conditions of scattered cloud, enhancement and suppression of the j _HONO values occurred by as much as 16%–70%, and 59%–80%, respectively. The integrated band area of the nπ^∗ transition for gas-phase nitrous acid yields an oscillator strength, f = (1.06 ± 0.044)×10⁻³ (based on clear-sky data), 19.1% higher than the value reported by Bongartz et al. (1991).     

1–5 μm imaging of 3CRR galaxies: the K–z relation and the geometry of the torus

It has been claimed by Taylor et al. that the low-redshift end of the K – z relation for radio galaxies is too bright by about half a magnitude owing to contributions from the obscured quasar nuclei. Such a result has major implications for the use of the K -band Hubble diagram in understanding the cosmological evolution of radio galaxies. In this paper we present 1–5-μm imaging data of a nearly complete sample of low-redshift radio galaxies; this approach allows us to determine accurately the strengths of any unresolved nuclear components in the galaxies. We detect nuclear sources in five targets, whose broad-band colours are consistent with reddened quasar spectra. In all the five cases the ratio of the inferred intrinsic near-infrared luminosity to the narrow-line luminosity is typical of quasars. We find a correlation between the inferred nuclear extinction and core-to-lobe ratio, which places constraints on the geometry of the torus. We find evidence for a shift of the K – z relation to fainter magnitudes, but by a much smaller amount (∼0.1 mag) than determined by Taylor et al. Under the assumption that the nuclear sources in radio galaxies have the same intrinsic near-infrared spectra as quasars, our multiwavelength images allow us to limit any possible shift to less than 0.3 mag.