Search results for "Pressure"
showing 10 items of 4493 documents
Forms and Processes of Settlement Pressure on Natural Systems
2021
The process of urbanisation is considered one of the most significant anthropic alterations of the environmental framework, and the present study attempts to understand the spatial characteristics of urban growth and their impacts on envi- ronmental components in two metropolitan areas of Sicily. Such rapid and unplanned urbanisation in Sicily has increased during the last three decades causing severe pres- sure on various natural resources. In this situation, the level of fragmentation and isolation of natural areas risks becoming worse. The question assumes a particular relevance in those local territorial portions, such as some urban and periurban areas, presenting relevant conditions of…
Continuous detection of new plant water status indicators in stage I of nectarine fruit growth
2019
Conventional irrigation management is often inefficient in responding to seasonal changes of tree water needs. The use of leaf- and fruit-based sensors might provide helpful insights on tree water status, although they have been poorly investigated so far. Fruit gauges and leaf patch clamp pressure (LPCP) probes were tested during stage I of nectarine fruit growth to evaluate if leaf turgor pressure and fruit size may serve as indicators of water deficit. This experiment was carried out in the 2017/18 season. Four irrigation levels were applied to ‘September Bright’ nectarine trees (100, 40, 20 and 0% of crop evapotranspiration, ETc) and data were collected during stage I of fruit growth. T…
Quality changes in fresh-cut mango cubes submitted to different gas partial pressure of active MAPs
2018
The study was performed to assess chemical-physical and sensory quality changes in 4±1°C stored fresh-cut mangos and to test the effect of active modified atmosphere packaging (MAP) with different gas partial pressures. Sicilian fruits of ‘Keitt’ mango (Mangifera indica L.) were immerged in hydrogen peroxide (H2O2) after being peeled. Next, the flesh was cut in cubes and dipped in citric acid (0.5%, w/v) and ascorbic acid (0.5%, w/v). Treated fruits were placed in a non-perforated high density polyethylene package flushing different gas mixtures and kept at 4°C for 21 days. We used four different gas partial pressures: a) 60 kPa N2, 30 kPa CO2 and 10 kPa O2; b) 30 kPa CO2 and 70 kPa N2; c) …
Plant-based water stress sensing in two olive cultivars with different physiological responses to drought
2022
A large portion of modern olive plantings is dominated by one main cultivar (‘Arbequina’) planted at super high density (SHD, 1,500 tree ha‑1), leading to a dangerous reduction in olive biodiversity. Very few cultivars have growth and productive patterns that suit the SHD system requirements. Partial intensification and mechanization with several cultivars may represent the safest and easiest alternative. The efficient use of limited natural resources, such as water, in SHD systems, requires precise management. Continuous plant-based sensing is a promising approach to managing water, mainly tested on the cultivar ‘Arbequina’. In this study, we evaluated the sensitivity of two promising indi…
Fitting the Stocking Rate with Pastoral Resources to Manage and Preserve Mediterranean Forestlands: A Case Study
2015
Pasture practices have affected Mediterranean forest ecosystems for millennia, and they are still quite widespread in mountainous areas. Nevertheless, in the last decades, the stability of forest ecosystems has been jeopardized due to the abandonment of traditional agro-pastoral practices, so that the gradual reduction of open areas due to progressive succession processes has caused a high increase of grazing pressure by livestock and wild ungulates feeding on forest areas. This paper aims at showing a methodological approach for evaluating the effect of applying measures in order to improve the grazing value of grasslands and ecotonal patches and lower the grazing impact on native woodland…
Parameterisation of bivalve functional traits for mechanistic eco-physiological dynamic energy budget (DEB) models
2013
Mechanistic models such as those based on dynamic energy budget (DEB) theory are emergent ecomechanics tools to investigate the extent of fitness in organisms through changes in life history traits as explained by bioenergetic principles. The rapid growth in interest around this approach originates from the mechanistic characteristics of DEB, which are based on a number of rules dictating the use of mass and energy flow through organisms. One apparent bottleneck in DEB applications comes from the estimations of DEB parameters which are based on mathematical and statistical methods (covariation method). The parameterisation process begins with the knowledge of some functional traits of a tar…
Synthetic and natural chromium bearing spinels: an optical spectroscopy study
2014
Four samples of synthetic chromium-bearing spinels of (Mg, Fe2+)(Cr, Fe3+)2O4 composition and four samples of natural spinels of predominantly (Mg, Fe2+)(Al, Cr)2O4 composition were studied at ambient conditions by means of optical absorption spectroscopy. Synthetic end-member MgCr2O4 spinel was also studied at pressures up to ca. 10 GPa. In both synthetic and natural samples, chromium is present predominantly as octahedral Cr3+ seen in the spectra as two broad intense absorption bands in the visible range caused by the electronic spin-allowed 4A2g → 4T2g and 4A2g → 4T1g transitions (U- and Y-band, respectively). A distinct doublet structure of the Y-band in both synthetic and natural spine…
1D Compression Behaviour of Opalinus Clay
2017
One of the main concerns related to tunnel excavations, drilling operations and wellbore stability in shales is the generation of excess pore water pressure due to changes in mechanical stress; therefore the consolidation of shales is a fundamental process that must be considered. This paper presents a compre- hensive methodology for analysing the compression and consolidation behaviour of shales. An apparatus to perform high-pressure oedometric tests is presented and an analytical method is introduced to analyse the shale consolidation behaviour, which allows information to be gathered on the coeffi cient of consolidation, stiffness, poroelastic properties, and permeability of the tested m…
Life cycle environmental assessment of retaining walls in unsaturated soils
2022
Abstract Retaining structures above groundwater level support soils that are usually in a state of partial saturation and subject to the actions of atmospheric agents. The current design approach considers the possible extremes of soil conditions – either totally dry or totally saturated – but it neglects matric suction’s contribution to soil shear strength. This work aims to describe how unsaturated-soil mechanics of can positively influence the sustainability of retaining structures through a holistic, multidisciplinary, geotechnical, and environmental analysis. The geotechnical analysis allows to estimate the lateral earth pressure of a geostructure in both unsaturated and extreme soil c…
The stabilization of a slope-viaduct system without closing traffic
2015
ABSTRACT A case history concerned with the stabilisation of a slope-viaduct system is reported. The two-carriageway viaduct was built 39 years ago on a rather gentle slope that did not show any sign of instability. In 2010 a landslide took place and damaged the viaduct. As the relocation of the motorway was deemed unpracticable, the alternative solution of stabilising the slope and repairing the viaduct was chosen. The owner asked to design remedial measures that did not require the closure of the viaduct. This was possible since the movements of the slided mass were slow and regular. The slope-viaduct system was stabilised by improving, firstly, the bearing conditions of the decks, then st…