Safe Design Suggestions for Vegetated Roofs

Rooftop vegetation is becoming increasingly popular because of its environmental benefits and its ability to earn green-building certification credits. With the exception of one international guideline, there is little mention of worker safety and health in vegetated-roof codes and literature. Observations and field investigations of 19 vegetated roofs in the United States revealed unsafe access for workers and equipment, a lack of fall-protection measures, and other site-specific hazards. Design for safety strategies and the integration of life-cycle safety thinking with green-building credits systems are the preferred methods to reduce risk to workers on vegetated roofs. Design suggestions have been developed to add to the body of knowledge. The findings complement several National Institute for Occupational Safety and Health (NIOSH) construction and prevention through design (PtD) goals and are congruent with NIOSH’s Safe Green Jobs initiative. Organizations that install and maintain vegetated roofs can utilize the findings to understand hazards, take precautions, and incorporate safety into their bids The published version of this article is available here: 10.1061/(ASCE)CO.1943-7862.0000500Support from the the Virginia Tech Occupational Safety and Health Research Center through the Kevin P. Granata Pilot Program funded by the Institute for Critical Technology and Applied Sciences

Using AMF inoculum to improve the nutritional status of Prunella vulgaris plants in green roof substrate during establishment

Arbuscular mycorrhizal fungi (AMF) have been shown to improve the growth, health, nutrient uptake, flowering and drought tolerance of many terrestrial plant species. Green roofs are generally deficient in nutrients, organic matter and water, and therefore AMF could be extremely beneficial in improving green roof plant performance. Despite this there is a lack of empirical research into artificially introducing AMF into green roof substrates. In this study, a commercial AMF inoculum was applied to Prunella vulgaris green roof plugs grown in small modules on a flat roof in Sheffield, UK. The modules were filled with commercial green roof substrate (80% small particle sized crushed brick, 20% green waste compost) to a depth of 100 mm. AMF inoculum was applied as four treatments: (i) directly with plug, (ii) mixed evenly into surrounding substrate, (iii) split between plug and substrate, (iv) control treatment with no inoculum added. Significantly greater levels of AMF colonisation of P. vulgaris roots was detected in all AMF treatments compared to the control. Low levels of AMF colonisation of P. vulgaris roots were also observed in the control treatment, confirming that low levels of AMF inoculum were present in this commercial substrate. Shoot phosphorous (P) concentration was improved in all AMF treatments, however there was no significant effect of any AMF treatment on P. vulgaris growth rate or biomass production. The highest AMF colonisation of P. vulgaris roots was observed when AMF inoculum was directly added to just the plug. Promisingly, P. vulgaris flowering time at the end of the first growing season was also extended in the plug AMF treatment only. This study has confirmed that commercial AMF inoculum can be used to successfully colonise plants and introduce AMF networks into green roof substrate. Although AMF inoculum was naturally present in the substrate used in this study, levels were extremely low, and unlikely to have any significant effect on plants. This study indicates that care should be taken in the use of AMF inoculum on green roofs, as the growth and health benefits of AMF are not always immediately apparent for green roof plants. In addition much more research is required in order to fully assess the extent of the benefits of AMF on green roof plants and to determine if their use can be financially viable

Excitonic recombination dynamics in shallow quantum wells

We report a comprehensive study of carrier-recombination dynamics in shallow AlxGa1-xAs/GaAs quantum wells. At low crystal temperature (2 K), the excitonic radiative recombination time is shown to be strongly enhanced in shallow quantum wells with x>0.01, consistently with a model that takes into account the thermal equilibrium between the three-dimensional exciton gas of the barrier and the two-dimensional exciton gas, which are closer in energy as x decreases. Furthermore, we demonstrate the existence of a thermally activated escape mechanism due to the low effective barrier height in these structures. The nonradiative recombination is shown to dominate the carrier dynamics for temperatures as low as 10 K for x≈0.01. Our experimental observations are analyzed using three different variational exciton calculations. In particular, we study the crossover from the two-dimensional to the three-dimensional behavior of the exciton, which occurs for x as low as 0.01 and affects mainly the oscillator strength, whereas the transition energies in shallow quantum wells can be calculated, to a large extent, using the same approximations as for conventional quantum wells. The peculiar behavior of the oscillator strength at the crossover to the weak confinement regime is obtained by expansion in a large basis

Financial wellbeing of Asian Americans

The Asian American population in the United States has been increasing. Research on the economic wellbeing of this minority group is far from being adequate. It is generally found that Asian Americans are more highly educated and have more wealth. Although the homeownership rate of this population is lower than the national average rate, the gap is gradually narrowing. Asian Americans are found to have more confidence in their financial future and have better management in their financial lives. In addition, Asian-owned businesses have been an important part of the U.S. economy and, as such, the self-employment status of Asian Americans has stimulated great interest for research. Large differences in financial behaviors exist among different groups in Asian Americans. This chapter serves the purpose to summarize past research on Asian American consumer finances and provide directions for future research.Includes bibliographical references

Ecology And Survival Of The Key Silverside, Menidia Conchorum, An Atherinid Fish Endemic To The Florida Keys

The key silverside, Menidia conchorum, is studied as an indicator of adaptations to environmental conditions in lagoonal and ponded water habitats of the lower Florida Keys. Evidence is presented to support the current view of ichthyologists that M. conchorum is a valid species. It occurs in lagoons from Grassy Key to Key West, Florida. This lagoonal habitat is shared by a distinct community. Such lagoons are characterized by rapid fluctuations and broad ranges of physico-chemical parameters. M. conchorum feeds on planktonic crustaceans and terrestrial insects. Maximum size for females is about 58 mm (SL) and 50.1 mm for males. Maturation appears to take place at about 40 mm. The species appears to live one year or less in nature. Reproduction continues year-round with peaks in fertility in the spring and fall. Its population size is seasonal, with a low point in late summer and fall. Nearly all populations inhabit lagoons altered by man and the species is judged as threatened with extinction

Ecology And Survival Of The Key Silverside, Menidia Conchorum, An Atherinid Fish Endemic To The Florida Keys

The key silverside, Menidia conchorum, is studied as an indicator of adaptations to environmental conditions in lagoonal and ponded water habitats of the lower Florida Keys. Evidence is presented to support the current view of ichthyologists that M. conchorum is a valid species. It occurs in lagoons from Grassy Key to Key West, Florida. This lagoonal habitat is shared by a distinct community. Such lagoons are characterized by rapid fluctuations and broad ranges of physico-chemical parameters. M. conchorum feeds on planktonic crustaceans and terrestrial insects. Maximum size for females is about 58 mm (SL) and 50.1 mm for males. Maturation appears to take place at about 40 mm. The species appears to live one year or less in nature. Reproduction continues year-round with peaks in fertility in the spring and fall. Its population size is seasonal, with a low point in late summer and fall. Nearly all populations inhabit lagoons altered by man and the species is judged as threatened with extinction

Capturing a rhodopsin receptor signalling cascade across a native membrane

G protein-coupled receptors (GPCRs) are cell-surface receptors that respond to various stimuli to induce signalling pathways across cell membranes. Recent progress has yielded atomic structures of key intermediates1,2 and roles for lipids in signalling3,4. However, capturing signalling events of a wild-type receptor in real time, across a native membrane to its downstream effectors, has remained elusive. Here we probe the archetypal class A GPCR, rhodopsin, directly from fragments of native disc membranes using mass spectrometry. We monitor real-time photoconversion of dark-adapted rhodopsin to opsin, delineating retinal isomerization and hydrolysis steps, and further showing that the reaction is significantly slower in its native membrane than in detergent micelles. Considering the lipids ejected with rhodopsin, we demonstrate that opsin can be regenerated in membranes through photoisomerized retinal–lipid conjugates, and we provide evidence for increased association of rhodopsin with unsaturated long-chain phosphatidylcholine during signalling. Capturing the secondary steps of the signalling cascade, we monitor light activation of transducin (Gt) through loss of GDP to generate an intermediate apo-trimeric G protein, and observe Gαt•GTP subunits interacting with PDE6 to hydrolyse cyclic GMP. We also show how rhodopsin-targeting compounds either stimulate or dampen signalling through rhodopsin–opsin and transducin signalling pathways. Our results not only reveal the effect of native lipids on rhodopsin signalling and regeneration but also enable us to propose a paradigm for GPCR drug discovery in native membrane environments