Systematic literature review of the performance characteristics of Chebyshev polynomials in machine learning applications for economic forecasting in low-income communities in sub-Saharan Africa.

Unlabelled: Chebyshev polynomials have unique properties that place them in a class of functions that are highly efficient in the approximation of non-linear functions. Machine learning techniques are being applied to solve complex non-linear problems in the financial markets where there is a proliferation of financial products. The techniques for valuing diverse portfolios of these products can be time consuming and expensive.

Estimation of Measurement Uncertainties for the DGT Passive Sampler Used for Determination of Copper in Water.

Diffusion-based passive samplers are increasingly used for water quality monitoring. While the overall method robustness and reproducibility for passive samplers in water are widely reported, there has been a lack of a detailed description of uncertainty sources. In this paper an uncertainty budget for the determination of fully labile Cu in water using a DGT passive sampler is presented.

Evaluation of a passive sampler for the speciation of metals in urban runoff water.

Metals in urban runoff water need to be monitored in order to estimate fluxes and assess their impact on the aquatic environment. Passive sampling is a useful and reliable emerging tool for measuring time averaged concentrations of metals in water bodies. This paper describes the deployment of a passive sampler to measure Cu, Ni and Zn in an urban runoff water treatment facility.

Performance of a passive sampler for the determination of time averaged concentrations of nitrate and phosphate in water.

A passive sampler device for the kinetic accumulation of nitrate (NO3(-)) and phosphate (HPO4(2-)) in water was developed and calibrated. The sampler incorporates an ion-exchange disk as the receiving phase and selectively collects nitrate and phosphate at sampling rates of 197 ± 43 and 75 ± 12 mL per day, respectively. Minimum exposure times under nutrient rich and nutrient poor conditions were estimated to be 3 and 27 days respectively for phosphate and 1 and 7 days respectively for nitrate.

Replacement predictions for drinking water networks through historical data.

Lifetime distribution functions and current network age data can be combined to provide an assessment of the future replacement needs for drinking water distribution networks. Reliable lifetime predictions are limited by a lack of understanding of deterioration processes for different pipe materials under varied conditions. An alternative approach is the use of real historical data for replacement over an extended time series.

Platinum group element concentrations and osmium isotopic composition in urban airborne particles from Boston, Massachusetts.

Platinum, Pd, Rh, and Os were found to occur at elevated concentrations in airborne particles (PM10) collected at urban sites in Boston, MA. Average Pt, Pd, Rh, and Os concentrations were 6.9 +/- 1.

Importance of automobile exhaust catalyst emissions for the deposition of platinum, palladium, and rhodium in the northern hemisphere.

An estimated 500 million vehicles worldwide are equipped with an exhaust catalyst that uses platinum group elements (PGE) as the main active components and thus contribute to global PGE emissions. Although PGE emitted from automobile exhaust catalysts were first believed to remain in the roadside environment, we propose here that fine PGE-containing particles in automobile exhaust have resulted in a widespread distribution of emitted PGE. Regional and long-range transport of PGE from automobile exhaust catalysts is supported by elevated PGE deposition in both a peat bog located 250 m from traffic and in central Greenland, respectively.

Platinum group elements in raptor eggs, faeces, blood, liver and kidney.

The increased use of platinum group elements (PGEs) in automobile catalysts and their emission into the environment has led to a concern over environmental and particularly biological accumulation. Specimens of samples from raptors are useful for the investigation of the impact of PGEs because these birds are found in both urban and rural environments and are invariably at the top of the food chain. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations were determined by quadrupole Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in eggs of the sparrowhawk (Accipiter nisus) and the peregrine falcon (Falco peregrinus), and in blood, liver and kidney of the peregrine falcon, while only Pt was determined in faeces of the peregrine falcon and the gyrfalcon (Falco rusticolus).

Environmental routes for platinum group elements to biological materials--a review.

The increased use of platinum group elements (PGE) in automobile catalysts has led to concern over potential environmental and biological accumulation. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations have increased in the environment since the introduction of automobile catalysts. This review summarises current knowledge concerning the environmental mobility, speciation and bioavailability of Pt, Pd and Rh.

Comparative tissue distribution of metals in birds in Sweden using ICP-MS and laser ablation ICP-MS.

Cadmium, copper, lead, palladium, platinum, rhodium, and zinc profiles were investigated along feather shafts of raptor and other bird species by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The distribution of external versus internal metal contamination of feathers was investigated. The species examined were peregrine falcon (Falco peregrinus), sparrowhawk ( Accipiter nisus), willow grouse (Lagopus lagopus), and house sparrow (Passer domesticus) in Sweden.

Metal diffusion properties of a Nafion-coated porous membrane in an aquatic passive sampler system.

A cellulose acetate membrane, positioned in a passive sampler system, was coated with the perfluorinated polymer Nafion. Aqueous metal transport through the membrane and the Nafion film was investigated. The Nafion-coated membrane prevents the transport of metals bound to natural organic material to the receiving phase in the passive sampler, while copper associated with small synthetic ligands pass through the Nafion film.

Impact of automobile emissions on the levels of platinum and lead in Accra, Ghana.

Examination of car fleet records in Accra demonstrates an increasing proportion of catalytic converter-equipped cars in the relatively old car fleet (average age 13 years) due to their import from developed countries. However, only leaded petrol is sold in Ghana. Lead anti-knocking additives, which are known to affect catalyst activity and promote thermal sintering and mechanical abrasion, may increase Pt emissions.

Performance of an in situ passive sampling system for metals in stormwater.

A passive sampler has been developed and is demonstrated in situ for urban runoff. The passive sampler is compared to conventional composite (time-dependent and flow-weighted) bottle sampling during and between storm events. The sampling was carried out at established stormwater stations; before and after a stormwater detention pond.

Scanning laser ablation-ICP-MS tracking of platinum group elements in urban particles.

While it has now been demonstrated that platinum group elements (PGE) are released from automobile catalysts into the environment, less is known about the form in which they are emitted and transported. Here we show that scanning laser ablation-inductively coupled plasma-mass spectrometry (scanning laser ablation-ICP-MS) can identify and track individual particles released from automobile catalysts present in environmental particulates and sediments. Particles with high PGE concentrations were found in the exhaust of gasoline and diesel vehicles equipped with catalytic converters.

Effect of stormwater runoff on metal distribution in the sediment and interstitial waters of an urban river.

Metals were analysed in the interstitial waters and sediments of an urban river, receiving stormwater and combined sewer overflow, over a two month period and interpreted in terms of rain events. Depth profiles for metal concentrations showed the highest interstitial water concentrations in samples with low sedimentary organic material. Storm events can both resuspend sediments and associated metal-rich interstitial waters and alter the metal distribution between interstitial water and sediment.