Mineral phosphorus drives glacier algal blooms on the Greenland Ice Sheet

Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet’s southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Application of Electrolyte-NRTL Model for Prediction of the Viscosity of Carbon Dioxide Loaded Aqueous Amine Solutions

A method based on the absolute-rate theory has been used and tested for estimation of the dynamic viscosity of CO₂ loaded aqueous solutions of a representative amine: monoethanolamine (MEA). In this approach the electrolyte-NRTL model is applied to estimate the activation free energy of the solution and consequently enable prediction of the dynamic viscosity of the strong electrolyte CO₂:MEA:H₂O system. Three different concentrations of the aqueous MEA solutions with 20, 30, and 43 wt %, in the temperature range from 40 to 70 °C, and CO₂ loadings from 0.1 to 0.5 mol of CO₂/mol of amine were selected for the model investigation. The model displays a reasonable prediction ability from experimental viscosity data in the whole range of system variables. It is shown that the activation free energy for the flow process can be closely estimated through the Gibbs free energy of mixing with a correction on the sign of the energy term in the model equation from positive to negative. The result reveals that, having a reliable thermodynamic model for a selected solution, the absolute-rate-theory approach is applicable for estimation of the viscosities of strong electrolyte systems such as CO₂ loaded alkanolamine solutions at different solution concentrations, temperatures, CO₂ loadings, and operating pressures for various amines and amine blends

Performance Measures for Traffic Signal Systems: An Outcome-Oriented Approach

This monograph is a synthesis of research carried out on traffic signal performance measures based on high-resolution controller event data, assembled into a methodology for performance evaluation of traffic signal systems. High-resolution data consist of a log of discrete events such as changes in detector and signal phase states. A discussion is provided on the collection and management of the signal event data and on the necessary infrastructure to collect these data. A portfolio of performance measures is then presented, focusing on several different topics under the umbrella of traffic signal systems operation. System maintenance and asset management is one focus. Another focus is signal operations, considered from the perspectives of vehicle capacity allocation and vehicle progression. Performance measures are also presented for nonvehicle modes, including pedestrians, and modes that require signal preemption and priority features. Finally, the use of travel time data is demonstrated for evaluating system operations and assessing the impact of signal retiming activities

Quantifying Benefits of Traffic Signal Retiming

Improvements in the quality of service on a signalized intersection or arterial can be interpreted as a reduction in the user cost of service, which is expected to induce demand based on economic theory. This report presents a methodology for measuring and interpreting changes to user costs, and determining whether demand was induced. High-resolution signal event data and Bluetooth device MAC address matching are demonstrated in three case studies with the purpose of quantifying the impacts of changes in signal timing plans. In the first case study, 21 months of vehicle volume data are used to test whether demand was induced by optimizing offsets on a Saturday plan. In the second case study, the increase in demand for pedestrian service is quantified with respect to the implementation of an exclusive pedestrian phase using an econometric model taking the effects of season, weather, and special events into account. Finally, the third case study demonstrates the use of vehicle travel time data in quantifying changes in user costs and environmental impact (tons of carbon). A method of describing changes in travel time reliability is also presented

Citizen Band (CB) Radio Communication Commenting on Indiana State Police Enforcement Activity

This audio was recorded from Citizen Band (CB) radio traffic on Channel 19 adjacent to mile marker 127.8 on I-65 in Indiana (Latitude 39.918554, Longitude -86.329367). The audio recording represents selected transmissions recorded at approximately 9:30am on 21 July 2010 documenting the public perception of an Indiana State Police enforcement detail that was occurring along I-65 and I-865 in Boone and Marion County. Approximately 12 different Indiana State Police personnel were involved in the enforcement detail at the time of the recording