Search results for "DF"
showing 10 items of 1699 documents
Impacts of oak deforestation and rainfed cultivation on soil redistribution processes across hillslopes using 137Cs techniques
2021
Abstract Background As one of the main components of land-use change, deforestation is considered the greatest threat to global environmental diversity with possible irreversible environmental consequences. Specifically, one example could be the impacts of land-use changes from oak forests into agricultural ecosystems, which may have detrimental impacts on soil mobilization across hillslopes. However, to date, scarce studies are assessing these impacts at different slope positions and soil depths, shedding light on key geomorphological processes. Methods In this research, the Caesium-137 (137Cs) technique was applied to evaluate soil redistribution and soil erosion rates due to the effects …
Research focusing on plant performance in constructed wetlands and agronomic application of treated wastewater – A set of experimental studies in Sic…
2019
Constructed wetlands are sustainable technologies for the treatment of wastewater. These biological systems have been widely studied throughout the world for more than 30 years; however, most studies have focused on the effects of design and engineering on pollutant removal from wastewater. Undoubtedly, agro-technical aspects have been given too little consideration by research. This paper reports the main results of a set of experiments carried out on two pilot horizontal subsurface flow systems in Sicily (Italy). Festuca, Lolium and Pennisetum spp. in combination and three emergent macrophytes-Arundo donax L., Cyperus alternifolius L. and Typha latifolia L.-alone, were assessed. The aim o…
Carbon stock increases up to old growth forest along a secondary succession in Mediterranean island ecosystems.
2019
The occurrence of old-growth forests is quite limited in Mediterranean islands, which have been subject to particularly pronounced human impacts. Little is known about the carbon stocks of such peculiar ecosystems compared with different stages of secondary succession. We investigated the carbon variation in aboveground woody biomass, in litter and soil, and the nitrogen variation in litter and soil, in a 100 years long secondary succession in Mediterranean ecosystems. A vineyard, three stages of plant succession (high maquis, maquis-forest, and forest-maquis), and an old growth forest were compared. Soil samples at two soil depths (0-15 and 15-30 cm), and two litter types, relatively undec…
Methane oxidation at a surface-sealed boreal landfill.
2009
Abstract Methane oxidation was studied at a closed boreal landfill (area 3.9 ha, amount of deposited waste 200,000 tonnes) equipped with a passive gas collection and distribution system and a methane oxidative top soil cover integrated in a European Union landfill directive-compliant, multilayer final cover. Gas wells and distribution pipes with valves were installed to direct landfill gas through the water impermeable layer into the top soil cover. Mean methane emissions at the 25 measuring points at four measurement times (October 2005–June 2006) were 0.86–6.2 m 3 ha −1 h −1 . Conservative estimates indicated that at least 25% of the methane flux entering the soil cover at the measuring…
Connectivity assessment in Mediterranean vineyards using improved stock unearthing method, LiDAR and soil erosion field surveys
2018
The interaction between processes and landforms is accelerated in vineyards due to bare tilled soils that enhance splash, runoff, and erosion. Traditionally, in order to assess these processes, the stock unearthing method (SUM) is considered a useful methodology that uses the graft union of the vine plant as passive bio-indicator of the topsoil level changes. However, SUM assumes that the topography between the rows is planar when development of a model of the current micro-topography is performed. Thus, we consider that there is a need to develop a new methodology (ISUM: improved SUM) that, by adding new measurements in the inter-row areas (at least 3), allows inclusion of the absent micro…
A generalized transitive closure for relational queries
1988
We augment relational algebra with a generalized transitive closure operator that allows for the efficient evaluation of a subclass of recursive queries. The operator is based on a composition operator which is as general as possible when the operator is required to be associative and when only relational algebra operators are used in its definition. The closure of such a composition can be computed using the well-known efficient algorithms designed for the computation of the usual transitive closure. Besides the case in which complete materialization of recursive relations are required, our strategy also yields an efficient solution in the case in which a selection is applied to the closur…
Species differences, influence of dose and application on biotransformation of phenol in fish.
1983
1. The metabolism of phenol in goldfish (Carassius auratus), rainbow trout (Salmo gairdneri) and goldenorfe ide (Leuciscus ideus melanotus) was compared. All three species produced phenyl sulphate, quinol sulphate and phenyl glucuronide. 2. The dose dependence of metabolism of phenol in goldfish was investigated. When the concn. of phenol was increased from 0.2 to 2 mg/l medium, that glucuronylated increased from 7 to 16% and that sulphated decreased from 63 to 47%. 3. The influence of mode of exposure on metabolism of phenol in goldfish was examined. Dietary exposure and uptake from medium was compared with i.p. injection. There was less metabolism in the order: dietary exposure greater th…
Theoretical study of the interaction between sodium ion and a cyclopeptidic tubular structure.
2007
DFT calculations have been carried out to describe the pathway of a sodium ion along the stacking direction of a tubular structure set up by five cyclopeptidic units, which can be considered a suitable model of a hollow tubular structure of indefinite length. A lattice of points inside the tubular structure is defined and the DFT interaction energy values with a sodium ion are obtained. The data allow predicting a zigzag path of the ion inside the hosting structure. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Ab initio study of tungsten trioxide WO3 in volume and surface area
2012
The structure and stability of different crystallographic phases of tungstentrioxide and the effect of potassium doping have been studied using ab initiocalcuations, both in the bulk and at the surface. The study was motivatedby experimental works on the growth of WO3 nanorods on a mica substrate.The nanorods adopt a hexagonal phase, which is metastable in bulk WO3.The first part of the manuscript reports the study of bulk WO3. For thehexagonal and monoclinique phase, the atomic structure is deterimined andcompared with different models that have been proposed in the experimentalliterature. The relative stability of the two phases is calculated as a functionof potassium doping. From this an…
Modeling and Query Language for Hospitals
2013
So far the traditional process modeling languages have found a limited use in the hospital settings. One of the reasons behind this delay has been the lack of clear definition of the sequence of activities that are carried out in the hospital. We propose a new modeling language (as a profile of UML Class diagrams) that captures all the useful features from various UML diagrams and can be used in modeling of the hospitals. Based on the modeling language, we have developed an easy-to-perceive graphical query language, which allows the physicians to retrieve directly from the various hospital databases information they need to better understand the flow of clinical processes.