Search results for "MAZ"
showing 10 items of 3205 documents
Are calanco landforms similar to river basins?
2017
In the past badlands have been often considered as ideal field laboratories for studying landscape evolution because of their geometrical similarity to larger fluvial systems. For a given hydrological process, no scientific proof exists that badlands can be considered a model of river basin prototypes. In this paper the measurements carried out on 45 Sicilian calanchi, a type of badlands that appears as a small-scale hydrographic unit, are used to establish their morphological similarity with river systems whose data are available in the literature. At first the geomorphological similarity is studied by identifying the dimensionless groups, which can assume the same value or a scaled one in…
The impact of soil erosion on soil fertility and vine vigor. A multidisciplinary approach based on field, laboratory and remote sensing approaches
2018
Soil erosion processes in vineyards, beyond surface runoff and sediment transport, have a strong effect on soil organic carbon (SOC) loss and redistribution along the slope. Variation in SOC across the landscape can determine differences in soil fertility and vine vigor. The goal of this research was to analyze the interactions among vines vigor, sediment delivery and SOC in a sloping vineyard located in Sicily. Six pedons were studied along the slope by digging 6 pits up to 60 cm depth. Soil was sampled every 10 cm and SOC, water extractable organic carbon (WEOC) and specific ultraviolet absorbance (SUVA) were analyzed. Erosion rates, detachment and deposition areas were measured by the po…
Evaluation of clogging in full-scale subsurface flow constructed wetlands
2016
Abstract Treatment processes that occur in constructed wetlands can result in gradual clogging of the porous medium. Clogging may result in hydraulic malfunction and/or reduced treatment performance. The aim of this study was to analyze the hydraulic aspects of horizontal subsurface flow (H-SSF) constructed wetlands (CWs), and, in particular, to investigate the clogging phenomena through in situ measurements of hydraulic conductivity of the gravel bed, quantification of accumulated clog matter and flow paths visualization by means of tracer tests. Removal efficiencies of chemical and physical contaminants were also assessed. Experiments were carried out in three full-scale H-SSF CWs in Sici…
Ecological risk assessment of pesticides in urban streams of the Brazilian Amazon
2022
Abstract The use of pesticides in households and peri-urban areas of the Amazon has increased notably during the last years. Yet, the presence of these contaminants in Amazonian freshwater ecosystems remains unexplored. Here, we assessed the exposure to 18 pesticides and 5 transformation products in the Amazon River and in the urban streams of Manaus, Santarem, Macapa, and Belem (Brazil). Pesticide concentrations were analyzed by liquid and gas chromatography methods. Ecological risks were assessed following a two-tiered approach. First, hazard quotients and an overall hazard index were calculated using toxicity data for standard test species of primary producers, invertebrates, and fish. S…
Parameterization of a comprehensive explicit model for single-ring infiltration
2021
International audience; Comprehensive infiltration models can simultaneously describe transient and steady-state infiltration behaviors, and therefore can be applied to a range of experimental conditions. However, satisfactory model accuracy re- quires proper parameterization, including estimating the transition time from transient to steady-state flow conditions (τcrit). This study focused on improving the estimation of two parameters – τcrit and a second constant called a – used in a comprehensive, explicit, two-term model for single ring infiltration (hereafter referred to as the SA model). Different studies have recommended that a should be as low as 0.45 to as high as 0.91. Furthermore…
Assessment of clogging in constructed wetlands by saturated hydraulic conductivity measurements
2019
Abstract This study aims at defining a methodology to evaluate Ks reductions of gravel material constituting constructed wetland (CW) bed matrices. Several schemes and equations for the Lefranc's test were compared by using different gravel sizes and at multiple spatial scales. The falling-head test method was implemented by using two steel permeameters: one impervious (IMP) and one pervious (P) on one side. At laboratory scale, mean K values for a small size gravel (8–15 × 10−2 m) measured by the IMP and the P permeameters were equal to 19,466 m/d and 30,662 m/d, respectively. Mean Ks values for a big size gravel (10–25 × 10−2 m) measured by the IMP and the P permeameters were equal to 12,…
Epistemologia dell’insegnante di matematica sulla sua conoscenza professionale. (Parte I: Quadro teorico e rassegna di alcuni risultati di ricerca).
2007
In this research the mathematics teacher’s point of view is investigated on his professional knowledge. In particular: What does he mean for “professionalism”? Does he really perceive himself as a “professional”? And how does he perceive himself as a “professional” or non a “professional”? Of what nature is his professional knowledge? On which bases are his professional practices founded? What are the sources and the limits of this knowledge? What, if any, epistemological status do his beliefs regarding the term “professional” have? The mathematics teacher’s epistemology, then, is the leading thread of the whole research. The data obtained about the teacher’s knowledge and beliefs are inter…
Epistemologia dell’insegnante di matematica sulla sua conoscenza professionale. (Parte IV: Risposte alle domande di ricerca D5-D9 e conclusioni).
2008
Le prime tre parti di questo lavoro si trovano nei precedenti tre numeri della rivista. Nella prima parte è stato descritto il quadro teorico ed è stata fatta una rassegna di alcuni risultati di ricerca sul tema in esame. Nella seconda parte è stata completata la rassegna dei principali risultati di ricerca e sono stati introdotti i problemi sui quali si è focalizzata questa ricerca. Nella terza parte è stata descritta la metodologia utilizzata per indagare l’epistemologia dell’insegnante di matematica sulla sua conoscenza professionale e sono stati riportati e discussi alcuni risultati ottenuti. In questa quarta e ultima parte si completa la descrizione e discussione dei risultati ottenuti…
Epistemologia dell’insegnante di matematica sulla sua conoscenza professionale. (Parte II: Altri risultati di ricerca. Domande di ricerca e ipotesi d…
2007
Nel numero precedente di questa rivista è riportata la prima parte di questo lavoro: il quadro teorico e una rassegna di alcuni risultati di ricerca. In questa seconda parte si completa la rassegna dei principali risultati di ricerca riguardanti il tema in esame e si descrivono i problemi sui quali si è focalizzata questa ricerca.
Epistemologia dell’insegnante di matematica sulla sua conoscenza professionale. (Parte III: Metodologia e risposte alle domande di ricerca D1-D4).
2007
Le prime due parti di questo lavoro si trovano nei precedenti due numeri della rivista. Nella prima parte è stato descritto il quadro teorico ed è stata fatta una rassegna di alcuni risultati di ricerca. Nella seconda parte è stata completata la rassegna dei principali risultati di ricerca sul tema in esame e sono stati introdotti i problemi sui quali si è focalizzata questa ricerca. In questa terza parte si descrive la metodologia utilizzata per indagare l’epistemologia dell’insegnante di matematica sulla sua conoscenza professionale e si riportano e discutono alcuni risultati ottenuti.