Assessing short- and long-term modifications of steady-state water infiltration rate in an extensive Mediterranean green roof

Green roof detention capacity is related to the steady-state infiltration rate, is, of the growing medium. With the aim to investigate short- and long-term modifications of the detention capacity of an extensive Mediterranean green roof, three mini-disk infiltrometer (MDI) measurement campaigns were conducted at construction, after one season and after five years of operation. A laboratory experiment was designed to separately measure is in the upper and the lower part of the substrate profile. During the first operating season, field is increased by a factor of 2.4 and 1.9 for near-saturated (applied pressure head, h0 = -30 mm) and quasi-saturated conditions (h0 = -5 mm), respectively. Similar rainfall height did not induce significant modifications in the upper layer of the laboratory columns, even if contribution of small pores to water infiltration tended to increase. Differently, is significantly decreased by a factor of 3.4-5.3 in the lower layer. After the simulated rainfall, the upper layer was less packed (mean bulk density, & rho;b = 1.083 kg m-3) and the lower layer was more packed (& rho;b = 1.218 kg m-3) as compared with the initial density (& rho;b = 1.131 kg m-3) and the lower part enriched in small particles. Short-term modifications in the experimental plot were thus attributed to fine particles washing-off and bulk density decrease in the upper layer, yielding an overall more conductive porous medium. After five years of green roof operation, field is did not further increase thus showing that the washing/clogging mechanism was complete after one season or it was masked by counteracting processes, like root development and hydrophobicity

Psychophysiological measures of stress in caregivers of individuals with autism spectrum disorder: a systematic review

Purpose: Parents of children with autism spectrum disorder (ASD) often self-report heightened levels of stress and physical health problems. This paper reviewed studies assessing physiological measures of stress among parents of children with ASD. Methods: Systematic database searches identified 15 studies meeting inclusion criteria. Studies were reviewed to determine: (a) control group characteristics; (b) caregiver and care recipient characteristics; (c) setting; (d) physiological measures employed; (e) physiological outcomes; and (f) stressor type. A measure of methodological quality was also applied. Results: Salivary cortisol was the most common physiological measure employed. A pattern of blunted physiological activity emerged within the reviewed studies, though some studies reported normal or even higher physiological activity among this population. Conclusions: Findings suggested dysfunction of the hypothalamic-pituitary-adrenal-axis and autonomic nervous system for some, but not all, parents of children with ASD. Further research is warranted

The Architectural Envelope: an Assistant for Components Design Choices

The global envelope to day focuses on it a lot of attention from architects, progressively replacing the classical concepts of wall and roof. It is a complex component, entrusted with the delicate goal of mediating between exterior and interior space, between a space boundary and a bearing structure. Its main parts are the glass wall, a substructure resisting the loads and transmitting them to the bearing structure, and the connection of the two. The latter, in turn, comprises a fitting and a bracket. The set of relationships between these components and sub-components needs the control of many conditions of consistency. The tool presented is an Assistant performing just this task helping the designer to select in each project situation the best couple of two main envelope components: fitting and bracket. The Assistant structure lends itself to implement an intelligent commercial product catalog. It seems also fit to manage component selections strongly conditioned by consistency constrains between collaborating elements

Testing an adapted beerkan infiltration run for a hydrologically relevant soil hydraulic characterization

Literature raises doubts about the usability of infiltrometer methods to characterize soils in a hydrological perspective since these methods often yield excessively high infiltration rates or saturated soil hydraulic conductivity, Ks, values. For a loam (AR) and a silty-clay (RO) soil, beerkan infiltration runs were adapted in the perspective to obtain usable soil data to predict rainfall partition into infiltration and rainfall excess. In particular, the initially nearly dry soil was sampled with different water volumes (15 or 30) and heights of water application (low, L, 0.03 m, and high, H, 1.5 m), and the BEST-steady algorithm was applied to determine sorptivity, S, and Ks. The H runs altered the surface soil layer more than the L runs but the response of the two soils to disturbance was different. For the AR soil, deterioration of the surface layer was almost complete close to the end of the run while, for the RO soil, it was concluded after applying one third of the overall used water volume. The least soil perturbing experiment (15L), that was carried out with the commonly recommended experimental protocol, yielded high S (91–118 mm/h0.5) and Ks (88–294 mm/h) values at the two sites, likely incompatible with formation of any rainfall excess. A soil perturbing experiment (30H) yielded significantly and substantially smaller S (26–40 mm/h0.5) and Ks (4–6 mm/h) values, that appeared potentially compatible with formation of rainfall excess. The gravitational potential energy, Ep, of the water used for the infiltration run explained most of the variance of both Ks and S. In conclusion, the infiltration run can be adapted in an attempt to induce a soil disturbance likely similar to that expected for a rainfall producing runoff. In a relatively dry initial status, complete deterioration can require less water for a silty-clay soil than a loam soil. The saturated soil hydraulic conductivity is more sensitive than soil sorptivity to the applied experimental methodology. Finally, the gravitational potential energy of the applied water could be used to establish a link between the hydrological process that has to be explained and a soil hydraulic characterization appropriate to reach the desired objective