351 research outputs found
Study of vegetation-atmosphere interactions over vineyards: CO2 fluxes and turbulent transport mechanics
No full textThe study of vegetation‒atmosphere exchanges is today of great interest in order to understand and model plant responses to environmental conditions and their potential influence on global climate change. A special attention is usually given to carbon dioxide (CO2) fluxes and, in general, natural ecosystems such as forests received more attention. In the present work we investigated vegetation‒atmosphere interactions over vineyards, focusing on the annual carbon budget and turbulent transport processes driving exchanges of mass and energy.
Vineyard is a complex ecosystem with distributed sources/sinks of scalars (water vapour, carbon dioxide, heat), where vines and soil surface combine to give the overall flux of the canopy. In Northern Italy vineyard inter-row is often grassed, playing then an important role in the whole carbon budget. In this context, the partitioning of net ecosystem CO2 exchange (NEE) into soil and vine components deserves a special attention. We monitored vineyard NEE applying the eddy covariance (EC) method for three years, while soil CO2 flux measurements have been carried on using soil chambers (transparent and dark). In 2015, the annual carbon budget of the vineyard was about ‒ 80 g C m‒2 y‒1, however the largest part of carbon assimilation was due to grassed soil compartment (‒ 60 g C m‒2 y‒1). The interannual variability of seasonal carbon budget showed to be high and significantly affected by heat waves and drought spells in summer. During the growing season of 2014, characterized by plenty of rainfall, NEE reached its maximum value of about ‒ 250 g C m‒2.
The organization in rows of the vineyard determines a peculiar turbulent transport dynamics within the canopy. However, the morphological structure of the vineyard is greatly variable over the year, shifting from an empty canopy during vine dormancy to dense foliage in summer. We investigated the influence of foliage development on turbulence statistics deploying a vertical array of sonic anemometers. Turbulent flow showed to be greatly influenced by canopy structure. Without leaves, turbulent regime is typical of a rough‒wall boundary layer flow, whereas at full foliage development it assumes the features of a mixing‒layer flow, even if the inflection point at canopy top is weak, due to sparseness of the vineyard. Coherent structures involved in momentum transport and their temporal scales have been also investigated, showing the increasing importance of sweeps throughout the growing season. The average duration of dominating coherent structures was in the order of 6 ‒ 10 s and no clear influence by canopy structure evolution was detected.
The research demonstrated the importance of long‒term monitoring of vegetation‒atmosphere exchanges, and also the complexity of turbulent transport dynamics in the canopy space. However, only a thorough comprehension of this mechanics could lead to a solid interpretation of the role of vegetation in fundamental biogeochemical cycles
Preventive effects of broccoli bioactives : role on Oxidative stress and cancer risk
No full textCruciferous vegetables (such as broccoli) seem to have an important role in cancer prevention, as suggested by the results of several epidemiological studies showing an inverse association between their consumption and cancer risk at several sites. This class of vegetables contains several antioxidants and provides glucosinolates, which are converted to isothiocyanates and indoles, the bioactives believed to be responsible for most of the protection against cancer development. Numerous mechanisms of action have been studied; they involve interconnected signaling pathways important for cancer growth and progression including the direct and indirect effect on oxidative stress, and modulation of phase I and phase II enzymes and of epigenetic mechanisms. In particular, brassica vegetables may contribute to reducing free radical-related molecular damage in subjects, such as smokers, with high exposure to oxidative stress. In this regard, the effect of broccoli intake on biomarkers of oxidative stress and cancer risk in smokers is briefly discussed
Disentangling the carbon budget of a vineyard: The role of soil management
No full textThe environmental sustainability of viticulture can be enhanced with the application of conservative management practices (e.g. resident vegetation or cover crop on the inter-row), which can lead to an increase of soil carbon (C) sequestration. However, studies disentangling the vineyard C budget are still very scarce. In this context, comparing vineyard net ecosystem CO2 exchange (NEE) with soil fluxes is especially useful. From January 2015 to August 2016, we continuously monitored vineyard NEE with the eddy covariance method and ground CO2 fluxes with an automated chamber system in a commercial vineyard in North Eastern Italy. At the site, inter-rows are covered with resident herbaceous vegetation, however, due to low soil permeability, soil cultivation (ripping or tillage) was performed on alternate alleys in autumn and, sometimes, spring in order to improve water infiltration. Measured annual soil respiration was comparable, but lower, to values estimated by previous studies in vineyards and the net uptake of the grass cover laid in the middle of yearly C budget range reported in the literature for grasslands. At the end of the measurement period, the vineyard ecosystem showed to be a net sink of CO2, absorbing around −233 gC m−2. However, the C sequestration could have been much greater if no soil cultivation had been applied. Indeed, the ground compartment was a source of CO2, but without inter-row cultivation it could have been a net sink, with an overall vineyard C budget of about −421 gC m−2. This confirms that grass cover of the inter-rows can play an important role in the C budget of woody crops. Additionally, the pattern of C fluxes reveals that the activity of herbaceous vegetation in summer decreased well before vines, thus reducing water competition during dry periods. These results provide important information for the tuning of management practices aimed at improving the environmental sustainability of viticulture
A Wearable Device for Hand Sensorimotor Rehabilitation Through Augmented Sensory Feedback
No full textThe loss of sensitivity of the upper limb due to central or peripheral neurological injuries severely limits the ability to manipulate objects, hindering personal independence. Non-invasive augmented sensory feedback techniques are used to promote neural plasticity hence to restore the grasping function. We devised a wearable device for hand sensorimotor rehabilitation capable of reliably detect transient tactile events based on custom piezoelectric polyvinylidene fluoride (PVDF) sensors and deliver discrete bursts of vibrations upon these events. We integrated the sensors into a fabric glove and tested the device in a pilot bench test exploring its ability to detect object contact and release as well as object slippage. Due to their broad bandwidth, the sensors proved to be suitable for both the applications: they responded with clear peaks when touching or releasing the object and increased the high-frequency content of the signal during slippage
Pathological changes in human islets
No full textPurpose of review: This paper reviews the most recent articles on human islet inflammation in type 1 and type 2 diabetes, in recurrent autoimmunity and alloimmunity, which can result in pancreatic graft failure. Finally, we examine data supporting the hypothesis that islet destruction is accompanied by regenerative phenomena aimed at restoring beta cell mass. Recent findings: Type 1 diabetes: Application of high-resolution magnetic resonance imaging and fluorescence of long circulating nanoparticles was successfully used in evaluating islet inflammation in animal models of autoimmune diabetes. Among environmental factors in type 1 diabetes, enteroviral beta-cell infection was reported in some Finnish type 1 diabetic patients. Finally, a family of modulators of cytokine signaling was reported to occur in human islets. Pancreatic islet transplantation: Several observations suggested that (a) interventions to activate, amplify, or sustain intra-islet endothelial cells may facilitate islet revascularization; and (b) the development of strategies aimed at preventing upregulation of proinflammatory molecules can improve islet transplantation. Type 2 diabetes: Multiple factors such as proinflammatory cytokines, high glucose and free fatty acids can contribute to islet inflammation in type 2 diabetes. Accordingly, type 2 diabetic islets show increased apoptotic phenomena and a series of functional defects. Beta-cell regeneration: A number of reports observed beta-cell neogenesis in rodent and in human pancreas. Newly formed beta-cells likely derive either from ductal cells or as results of proliferation phenomena from pre-existing beta cells. Summary: Increasing evidence supports the hypothesis that islet inflammation together with beta-cell dysfunction is a common feature to both type 1 and type 2 diabetes
Characterization of microclimate and turbulent fluxes at a Mediterranean kiwi orchard covered with hail-protection net
No full textScreens and covers are increasingly used to protect crops from pests and extreme meteorological events. Their use affects plant microclimate and physiological responses as well, but this is only partly understood, particularly when considering the interaction among the cover and the training system. This study focuses on the microclimatic effects of the use of a hail protection net and an horizontal (pergola) kiwifruit canopy. The system splits the orchard environment in three distinct layers, determining a shaded understory, a space comprised between the canopy and the net, and the atmosphere above the net. To accent the effects, we considered a high-water demanding crop-kiwifruit, in an environment characterized by high evaporative demand (Bernalda, southern Italy).Three full eddy covariance and radiative balance equipment were used to assess fluxes (carbon dioxide, water vapor, and sensible heat) in the three layers and monitor meteorological variables (air temperature and relative humidity, wind, upward and downward short and long wave radiation, carbon dioxide and water vapor concentrations). Data from a typical clear-sky summer day are considered in this paper.While the net strongly reduced wind speed, it had a modest impact on all other variables. Conversely, the tick canopy layer had a major impact on all variables, determining a highly shaded, cooler and more humid understory, with very light wind. Nevertheless, the combination of high relative humidity and presence of the net was able to reduce the net loss of longwave radiation from the canopy during night, mitigating its cooling under these conditions.The reduction in wind speed and the increase in incoming longwave radiation around the crop, observed at night time, indicate potential valuable mechanisms that may be exploited to decrease water needs and prevent late frosts in the context of climate change, where extreme climatic events are more frequent and crop water requirements continue to increase
Nitrogen removal optimization in a sequencing batch reactor treating sanitary landfill leachate
No full textBiological nitrogen removal via nitrite may represent a promising process for the optimization of nitrogen removal, in particular in the presence of a low biodegradable COD/TKN ratio. In the present study a lab-scale sequencing batch reactor (SBR) was monitored for approximately 2 years to evaluate the use of dissolved oxygen (DO), pH and oxidation-reduction potential (ORP) as monitoring parameters in order to optimize nitrogen removal via nitrite from leachate generated in old sanitary landfills. The SBR manifested a nitrification efficiency exceeding 99% whereas, due to the low biodegradability of the organic matter presents in the leachates, COD removal reached approximately 40% and the addition of external COD was required to accomplish denitrification process. Moreover, the results demonstrate that DO, pH and ORP are reliable parameters for use in the monitoring of nitritation and denitritation processes in SBRs treating landfill leachates. Through manual modification of the length of the SBR phases to achieve nitrogen removal via nitrite, the nitritation and denitritation processes were rendered unstable leading to the saving of 20% in addition of external COD, almost half the theoretically achievable value. Furthermore, the low dissolved oxygen concentration applied during the oxic phases in an attempt to increase the nitritation process would appear to cause the settling characteristics of the activated sludge to deteriorate
Protection net and the canopy layer decouple gas exchanges, affecting carbon and water fluxes: the case of a kiwifruit orchard in a Mediterranean environment
No full textCovers are increasingly used to protect crops from pests and extreme meteorological events. Their use affects plant microclimate and physiological responses as well, but this is only partly understood, particularly when considering the interaction among the cover and the training system. This study focuses on the microclimate effects of the concurrent use of a horizontal hail protection net and tree canopy. The system splits the orchard environment in three layers, giving a shaded understory, a volume comprised between the canopy and the net, and the atmosphere above the net. To accent the effects, we considered a high-water demanding crop – kiwifruit, in an environment characterized by high evaporative demand (Bernalda, southern Italy). Three full eddy covariance and radiative balance-equipments were used to synchronously monitor meteorological variables (air temperature and relative humidity, wind, upward and downward short and long wave radiation, carbon dioxide and water vapour concentrations) and infer fluxes (carbon dioxide, water vapour, and sensible heat) between the three layers. Data from a typical clear sky summer day, at different hours, are considered in this paper. While the net strongly reduced wind speed (-79%), it had a modest impact on all other variables. Conversely, the tick canopy layer had a major impact on all variables, determining a highly shaded, cooler and more humid understory, with very modest wind and higher carbon dioxide concentration. Most carbon assimilation and evapotranspiration were due to the tree canopy, while the understory played as a carbon source via respiration. The combination of the net and the pergola training system determined low energy understory conditions, which facilitate the buildup of water vapour and carbon dioxide and their recycling within the system. Given the large and increasing use of crop covers, a deeper understanding of their impacts on the drivers of climate change, such as the carbon, water and energy fluxes, is necessary
Assessing Workload, Visual Concentration, and Motor Performance in a Fine Manipulation Task: A Novel Experimental Setup
No full textThe absence of tactile-feedback negatively impacts manipulative skills, causing reliance on visual-feedback and increased cognitive effort. Assessing augmented-feedback effects in simple motor tasks yields inaccurate results. Therefore, we developed an experimental setup to assess differences in workload, visual concentration and motor performance during a pick-and-lift task under single- (motor) and dual-task (motor and cognitive) conditions. NASA-TLX was administered to quantify workload, while an eye tracking system provided gaze focus data. Motor coordination metrics were extracted from forearm muscle activity and grasp forces measured through an instrumented object. The setup was validated on eight healthy individuals, proving capable of providing insights into motor and cognitive performances. Specifically, the higher cognitive load condition led to reduced focus on the object (-10.8%) and increased grip force (31.4%). Encouraged by the outcomes, we plan to use this methodology to evaluate the impact of augmented-feedback on motor and cognitive performances in individuals with tactile deficits
Modulation of plasma antioxidant levels, glutathione S-transferase activity and DNA damage in smokers following a single portion of broccoli: a pilot study
No full textBACKGROUND: Broccoli is a rich source of bioactive compounds (i.e. glucosinolates, carotenoids, vitamin C and folate) that may exert an antioxidant effect and reduce oxidative damage. The objective of this pilot study was to investigate the effect of broccoli consumption on carotenoids, vitamin C and folate absorption, glutathione S-transferase (GST) activity, and oxidatively induced DNA damage in male smokers.
METHODS: Ten healthy subjects consumed a single portion of steamed broccoli (250 g) with cooked pasta. Blood was drawn at baseline and at 3, 6 and 24 h from consumption.
RESULTS: Broccoli significantly (P≤0.01) increased plasma level of vitamin C and folate (+35% and 70%, respectively) at 3 h, and β-carotene (+8%) at 6 h. A modulation of GST activity occurred in plasma 6 h after broccoli consumption. A significant(P≤0.01) reduction of the levels of H2O2-induced DNA damage (−18%) was observed in blood mononuclear cells 24 h after broccoli intake in GSTM1 positive, but not in GSTM1 null subjects.
CONCLUSION: One portion of broccoli increased plasma antioxidant levels, modulated plasma GST activity and improved cell resistance against H2O2-induced DNA damage in healthy smokers. These results support the importance of consuming fruit and vegetable regularly
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