41 research outputs found
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Nitrate Biogeochemistry and Reactive Transport in California Groundwater: LDRD Final Report
Nitrate is the number one drinking water contaminant in the United States. It is pervasive in surface and groundwater systems,and its principal anthropogenic sources have increased dramatically in the last 50 years. In California alone, one third of the public drinking-water wells has been lost since 1988 and nitrate contamination is the most common reason for abandonment. Effective nitrate management in groundwater is complicated by uncertainties related to multiple point and non-point sources, hydrogeologic complexity, geochemical reactivity, and quantification of denitrification processes. In this paper, we review an integrated experimental and simulation-based framework being developed to study the fate of nitrate in a 25 km-long groundwater subbasin south of San Jose, California, a historically agricultural area now undergoing rapid urbanization with increasing demands for groundwater. The modeling approach is driven by a need to integrate new and archival data that support the hypothesis that nitrate fate and transport at the basin scale is intricately related to hydrostratigraphic complexity, variability of flow paths and groundwater residence times, microbial activity, and multiple geochemical reaction mechanisms. This study synthesizes these disparate and multi-scale data into a three-dimensional and highly resolved reactive transport modeling framework
Learning Objects, Learning Objectives and Learning Design.
Educational research and development into e-learning mainly focuses on the inclusion of new technological features without taking into account psycho-pedagogical concerns that are likely to improve a learner's cognitive process in this new educational category. This paper presents an instructional model that combines objectivist and constructivist learning theories. The model is based on the concept of a learning objective which is composed of a set of learning objects. A software tool, called the Instruction Aid System (IAS), has been developed to guide instructors through the development of learning objectives and the execution of the analysis and design phases of the proposed instructional model. Additionally, a blended approach to the learning process in Web-based distance education is also presented. This approach combines various event-based activities: self-paced learning, live e-learning and the use of face-to-face contact in classrooms
Search for Higgs boson decays into a pair of light bosons in the bbμμ final state in pp collision at √s=13 TeV with the ATLAS detector
A search for decays of the Higgs boson into a pair of new spin-zero particles, H→aa, where the a-bosons decay into a b-quark pair and a muon pair, is presented. The search uses 36.1fb−1of proton–proton collision data at √s=13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% confidence level are placed on the branching ratio (σH/σSM) ×B(H→aa →bbμμ), ranging from 1.2 ×10−4to 8.4 ×10−4in the a-boson mass range of 20–60GeV. Model-independent limits are set on the visible production cross-section times the branching ratio to the bbμμ final state for new physics, σvis(X) ×B(X→bbμμ), ranging from 0.1fb to 0.73fb for mμμ between 18 and 62GeV
Delivering better outcomes through customer-led project management: the case of the major project BT 21st Century Network in the UK
Traditional approaches of major project management take the strategy of selecting a supplier-led prime/systems integrator. Although this strategy pushes a significant amount of risk to the supplier, project performance may suffer due to lower engagement of the customer in the anticipation of potential issues involving a major project. Thus, this research investigates the implications of the customer, as opposed to a selected external supplier, assuming the role of systems/prime integrator, as a Problem Structuring Method (PSM) to better deal with the soft side and uncertainties of the project. A case study approach is conducted on the major project BT 21st Century Network (BT21CN) to demonstrate that customer-led systems integration projects may provide more balance in the relationship and distribution of risks between supplier and customer, having a positive impact on project performance, accelerating the development of BT’s organisational capabilities, and producing better project outcomes in the long term