The Performance Analysis of Two Relatively Small Capacity Urban Retrofit Stormwater Controls

This paper details field investigations that were conducted on the performance of small capacity urban retrofit stormwater control measures. The objective of the two year study (2013–2015) was to provide performance data on stormwater retrofits that could not be fully sized according to conventional standards due to space constraints. In many states performance credits are not granted to stormwater management controls that are not designed to manage regionally derived water quality volumes. In retrofit applications there may exist numerous limitations to conventionally sized systems such as limited rights of way, setback distances or existing utilities. The larger scale objective of green infrastructure implementation is to improve receiving water quality and therefore even undersized systems, to some extent, meet this objective. This study introduces data on two systems: an innovative bioretention design with a water treatment residual amended filter media and an internal storage reservoir; and an undersized linear subsurface gravel wetland sized to optimize both phosphorus and nitrogen removal. The systems were retrofitted into existing developed areas and were sized at less than the water quality volume due to limited space at each location. The bioretention system (IBSC) was constructed in a commercial area in the town of Durham, NH in summer 2011 and the subsurface gravel wetland system (SGWSC) was constructed in a narrow drainage right of way in a residential neighbourhood of Durham, NH in the fall of 2013. Sediment and metal removals for both undersized systems were high with median removal efficiencies in the SGW of 75% for both total suspended solids (TSS) and total zinc (TZn). The Durham IBSC recorded median removal efficiency (RE) of 86% for TSS and TZn. Total phosphorus (TP) REs were higher than conventional bioretention systems with the subsurface gravel wetland system achieving a median RE of 53% and the Durham IBSC achieving a median RE of 40% for TP. Both systems reduced total nitrogen (TN) by approximately 20% (23% for SGWSC and 21% for Durham IBSC) with median effluent concentrations of 1.4 mg/L. This project was funded by the U.S. Environmental Protection Agency Region 1, Regional Applied Research Effort (RARE) Program. Additional information can be found in the full project report Performance Analysis of Two Relatively Small Capacity Urban Retrofit Stormwater Controls (Houle et al. 2015)

Non-reciprocal few-photon devices based on chiral waveguide-emitter couplings

We demonstrate the possibility of designing efficient, non reciprocal few-photon devices by exploiting the chiral coupling between two waveguide modes and a single quantum emitter. We show how this system can induce non-reciprocal photon transport at the single-photon level and act as an optical diode. Afterwards, we also show how the same system shows a transistor-like behaviour for a two-photon input. The efficiency in both cases is shown to be large for feasible experimental implementations. Our results illustrate the potential of chiral waveguide-emitter couplings for applications in quantum circuitry.Comment: Mathematica notebook attached for calculation of detection probabilitie

Evaluación del ciclo de vida aplicada en agrocadenas productivas : un instrumento de gestión ambiental para el diseño de políticas

La Evaluación del Ciclo de Vida del Producto (ECV) ha sido sugerida como un instrumento adecuado para ampliar el análisis y formulación de estrategias y políticas al utilizar el enfoque de Cadenas Globales de Mercancías. En este artículo se analizan los alcances de la aplicación de la ECV en diferentes sistemas de gestión ambiental lo cual permite establecer las áreas de operación de las empresas en las cadenas en las cuales la dimensión ambiental puede ser considerada. En ese sentido se detectan temas centrales, tales como el diseño de los productos y sus consecuencias en la cadena de abastecimiento, lo cual conlleva necesidades de coordinación inter-empresariales que en el contexto de las cadenas muestran un gran potencial para la formulación de estrategias y políticas. Al traducir estos elementos en cadenas agroindustriales se determinan los puntos críticos en los procesos productivos para el mejoramiento del perfil ambiental de las cadenas considerando adicionalmente las condiciones particulares de cada cadena en términos de su comportamiento sectorial, la influencia del consumidor y otros actores relacionados, el desarrollo organizacional y las posibilidades de diferenciación de productos utilizando el aspecto ambiental como elemento estratégico.Life Cycle Assessment (LCA) has been suggested as an appropriate tool for widening policy and strategy design when Global Commodity Chains approach is applied. Various environmental management systems are analyzed in this article, in order to determine scopes of LCA' applications by firms and producers participating in commodity chains. In that sense, some main issues are detected such as product design and its consequences on the supply chain. These introduce the necessity of inter-firm coordination in commodity chain operations, which are important for policy and strategy design. When we consider these issues in agro-industrial chains in Costa Rica, it helps in determining the hot spots in the production process which require improvements from environmental perspective. But additional specific conditions of the commodity chains are related, such as the sectoral behaviour, consumer and other stakeholders influence, organization of the chain and available options for product differentiation considering environment as a strategic element