1,720,976 research outputs found
Groundwater-dependent ecosystems as transfer vectors of nitrogen from the aquifer to surface waters in agricultural basins: The fontanili of the Po Plain (Italy)
No full textThe most spread groundwater-dependent ecosystems in the River Po valley are semi-natural lowland springs called “fontanili”. They provide specific habitats and support high biodiversity, but are often strongly impaired by agricultural pollution. In the present study we seasonally monitored the discharge and nitrogen concentration of 48 fontanili from the Adda and the Ticino river basins. We observed a wide spatial variability of both NO3-N concentrations and flows. The annual NO3-N loads ranged from <1 to 75 t y−1 and < 1 to 29 t y−1 in the Adda and Ticino basins respectively. In the springs characterized by variable discharge the N loads were exported mostly during the summer season when water table level was elevated mainly due to irrigation. Upscaling the mean NO3-N load to each river catchment based on the total number of springs, we obtained an aerial export of 33.2 ± 6.0 and 12.5 ± 3.2 kg y−1 ha−1. Such loads accounted for the 30.4 and 21.5% of the N surplus estimated for the Adda and Ticino basins respectively. Random Forest analysis was performed to identify the most important environmental variables influencing the nitrate contamination in the spring waters. A total of 22 explanatory variables related to N sources, land uses, intrinsic hydrogeologic and soil proprieties, in “situ” and remotely sensed variables were considered. The percent of soil cultivated with maize in a 500 m radius buffer area surrounding the sampling site, the N from manure and the distance of each spring from the main river were the most effective factors in controlling the NO3-N concentration in the fontanili water. The outcomes of this work open up to achievable management prospects for the protection and recovery of fontanili waters, and can be particularly useful for water managers in identifying areas and sites where restoration plans should be a priority
Evaluation of nitrate sources and transformation in the Oglio River watershed.
No full textIn agricultural watersheds, the management of nitrate contamination in rivers requires the understanding of the existing relationships between soil, groundwater and surface water. The reported data correspond to three sampling campaigns, conducted in different seasons on surface water in a Nitrate Vulnerable Zone of Lombardy (Northern Italy). The Oglio River, its tributaries, one spring, and effluents from wastewater treatment plants were sampled to determine N content, speciation and nitrate isotopes. The nitrate content increased along the Oglio River, mostly due to groundwater inputs. In summer, nitrate tended to decrease at the downstream reach, whilst this trend was not clear in autumn and winter campaigns. In summertime chemical and isotopic data suggest the presence of weak denitrification in the Oglio riverbed. Chemical, isotopic data and flow measurements allow the definition of the N fluxes and identification of sources and processes affecting the nitrate concentration in the river
Stable isotopes of dissolved nitrate and boron as indicators of the origin and fate of nitrate contamination in groundwater: results from the western Po Plain (Northern Italy).
No full textStable isotopes of dissolved nitrates and boron represent a powerful tool, complementary to existing monitoring data, enabling the identification of nitrate sources, the assessment of their relative contribution to nitrate pollution and the quantification of nitrate transport and removal processes. This contribution aims to present groundwater isotope data obtained in an area of 15 000 km2 of the western Po plain. Nitrate isotope data show that synthetic fertilisers and anthropogenic organic matter are the main sources of contamination. δ11B allows the discrimination between manure derived and sewage derived contamination. Results indicate that even in agricultural areas, contamination from sewage exists. Samples from the suburban area of Milan, where sewage was considered the most likely source of contamination, show instead a δ11B typical for cattle manure. This study demonstrates that the attribution of the contamination to a source based solely on present-day land use may lead to inappropriate conclusions
Evalutation and Rehabilitation of Stroke Patients Using Robot-Aided Techniques
No full textThis paper presents two robot devices for use in the rehabilitation of upper limb movements and reports the quantitative parameters obtained to characterize the rate of improvement, thus allowing a precise monitoring of patient's recovery. A one degree of freedom (DoF) wrist manipulator and a two-DoF elbow-shoulder manipulator were designed using an admittance control strategy; if the patient could not move the handle, the devices completed the motor task. Two groups of chronic post-stroke patients (G1 n=7, and G2 n=9) were enrolled in a three week rehabilitation program including standard physical therapy (45 min daily) plus treatment by means of robot devices, respectively, for wrist and elbow-shoulder movements (40 min, twice daily). Both groups were evaluated by means of standard clinical assessment scales and a new robot measured evaluation metrics that included an active movement index quantifying the patient's ability to execute the assigned motor task without robot assistance, the mean velocity, and a movement accuracy index measuring the distance of the executed path from the theoretic one. After treatment, both groups improved their motor deficit and disability. In G1, there was a significant change in the clinical scale values (p0.53 p<0.03). Our findings suggest that robot-aided neurorehabilitation may improve the motor outcome and disability of chronic post-stroke patients. The new robot measured parameters may provide useful information about the course of treatment and its effectiveness at discharge
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evaluation of upper limb sense of position in healthy individuals and patients after stroke.
No full textThe aims of this study were to develop and evaluate reliability of a quantitative assessment tool for upper limb sense of position on the horizontal plane. We evaluated 15 healthy individuals (controls) and 9 stroke patients. A robotic device passively moved one arm of the blindfolded participant who had to actively move his/her opposite hand to the mirror location in the workspace. Upper-limb's position was evaluated by a digital camera. The position of the passive hand was compared with the active hand's 'mirror' position. Performance metrics were then computed to measure the mean absolute errors, error variability, spatial contraction/expansion, and systematic shifts. No significant differences were observed between dominant and non-dominant active arms of controls. All performance parameters of the post-stroke group differed significantly from those of controls. This tool can provide a quantitative measure of upper limb sense of position, therefore allowing detection of changes due to rehabilitation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Factors affecting agricultural nitrogen removal in riparian strips: Examples from groundwater-dependent ecosystems of the Po Valley (Northern Italy)
No full textThe role of riparian ecosystems in mitigating the effects of diffuse agricultural sources is recognized in several regulatory measures and public policy initiatives in many parts of the world. This study aimed to evaluate the N buffering capacity of semi-natural riparian zones associated with spring-fed lowland streams, also known as "fontanili", representing the most important groundwater-dependent ecosystems in Northern Italy. Monitoring parcels were set up in nine riparian sites selected to cover a range of different soil properties and hydrogeological settings, and to sustain the evaluation of the main drivers affecting their N removal efficiency. Subsurface water level, nutrient concentrations and the main hydro-chemical parameters were monitored along transects of piezometers installed from crop fields to the spring channels. On selected samples from two sites stable isotopes of the water molecule were also determined. Median NO3- input concentrations from adjacent cropland to the riparian sites ranged from 0.10 to 21 mg NL-1, with maximum values exceeding the drinking water limit recorded during the summer and winter fertilization periods. Highly variable groundwater nitrate patterns were found in the riparian areas, including short nitrate plumes extending from the adjacent cropland into some riparian zones, or in others, small patches where NO3- declined at variable distance from the stream. Some chemical indicators (e.g., NO3-/Cl- ratio, O-2, DOC) suggested that NO3- attenuation was mostly due to the denitrifying activity occurring in the subsurface aquifers in specific conditions (hot spots and moments), although, in some cases, physical processes such as dilution also contributed. The overall N removal efficiency was greater than 90% in four sites, 74%, 34% and 30% in three sites, and zero in the remaining two sites. Useful predictors of the nitrate removal capacity were factors linked to the water residence time, such as the hydraulic conductivity, the soil texture and the slope of the riparian profile, together with the water table depth and soil organic carbon. A combination by standardized averaging of these five factors supported a clear discrimination of sites with zero or low N removal effectiveness from those with high efficiency
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