166 research outputs found
Multi-objective optimization of run-of-river hydropower: hydrologic disturbance, stream connectivity and economic profitability
Although run-of-river hydropower represents a key source of renewable energy, it cannot prevent stresses on river ecosystems. This is especially true in mountain regions, where the outflow of a plant is placed several kilometres downstream of the intake, inducing the depletion of river reaches of considerable length.
In this thesis, multi-objective optimization is used in the design of the capacity of run-of-river plants to identify optimal trade-offs between contrasting objectives: the maximization of the profitability and the minimization of the impact induced by the plant. The latter is quantified either as the upstream/downstream changes of a set of ecologically-relevant flow metrics, or as the loss of hydrological connectivity in the impacted river reaches.
Optimal plant sizes are devised for several case studies belonging to catchments in Italy and UK.
Results show that the duration of economic optimal design capacity is strongly affected by the nature of the flow regime at the plant intake.
In particular, the analysis emphasizes the important distinction between persistent (reduced variability) and erratic (enhanced variability) streamflow regimes.
Multi-criteria optimization indicates that in persistent regimes a trade-off between profitability and hydrologic impact is achieved reducing the plant capacity below the economic optimum, whereas in erratic regimes distinct trade-offs are available depending on the relative importance of the different flow statistics.
This work also confirms that water abstractions for human exploitation induce ecologically-meaningful and quantifiable impacts on the hydrologic connectivity of altered river reaches, which may limit significantly migratory movements of fish. The application of a probabilistic eco-hydrological model to reproduce the observed immigration rates of Atlantic salmon in a Scottish river shows that limitations of connectivity are more pronounced in years where exceedance probability of relatively high flow is low.
The analyses conducted in this thesis show that residual flows represents a key decision variable to preserve the connectivity of impacted river reaches, and thus should be carefully considered in planning environmental policy actions.
The analytical tools developed in this thesis could provide a clue for evaluating the environmental footprint of run-of-river plants and improve sustainability of energetic exploitation of surface water
COPSEC: Compliance-Oriented IoT Security and Privacy Evaluation Framework
A rising number of Internet of Things (IoT) security and privacy threats have been documented over the last few years. However, IoT devices' domain designs are out-of-date and do not take into consideration the changing dangers associated with them. In this paper, we present COPSEC, a novel framework for evaluating whether IoT devices are compliant with security guidelines and privacy regulations. We extract metrics from existing guidelines and regulations and test them on a set of devices by performing hundreds of automated experiments. Our results indicate not only that these devices are not compliant with basic security guidelines, but also that their data collection operations may introduce privacy risks for the users that adopt them
Magmatic Signature in Submarine Hydrothermal Fluids Vented Offshore Ventotene and Zannone Islands (Pontine Archipelago, Central Italy)
Geochemical investigations carried out on submarine hydrothermal fluids vented offshore the Pontine Islands (Tyrrhenian Sea) revealed the existence of gas vents to the W of Zannone Island and SW of Ventotene Island. The geochemical features of the CO2-rich gas samples show a clear mantle-derived signature with3He/4He of 3.72-3.75 Ra and 1.33 Ra at Zannone and Ventotene, respectively. Gas geochemistry denotes how CO2-rich gases undergo fractionation processes due to CO2dissolution to a variable extent favoring enrichment in the less soluble gas species, i.e., CH4, N2, and He. The carbon isotope composition of CO2, expressed asδ13C vs. V-PDB, ranges from -0.71 and -6.16‰ at Zannone to 1.93‰ at Ventotene. Preliminary geothermometric and geobarometric estimations indicate equilibrium temperatures in the range of 150-200°C at Zannone and >200°C at Ventotene besides H2O pressures in the range of 5 bar and 20 bar at Zannone and Ventotene, respectively. Although the latest volcanic activity at the Pontine Archipelago is dated Middle Pleistocene, the combination of the new geochemical information along with geothermometric estimations indicates that cooling magmas are likely releasing enough thermal energy to form an efficient hydrothermal system
Hazard Scenarios Related to Submarine Volcanic-Hydrothermal Activity and Advanced Monitoring Strategies: A Study Case from the Panarea Volcanic Group (Aeolian Islands, Italy)
Geohazards associated to submarine hydrothermal systems still represent a tricky enigma to face and solve for the scientific community. The poor knowledge of a submarine environment, the rare and scarce monitoring activities, and the expensive and sometimes complicated logistics are the main problems to deal with. The submarine low-energy explosion, which occurred last November 3, 2002, off the volcanic island of Panarea, highlighted the absence of any hazard scenario to be used to manage the volcanic crisis. The "unrest" of the volcanic activity was triggered by a sudden input of deep magmatic fluids, which caused boiling water at the sea surface with a massive CO2 release besides changes in the fluids' geochemistry. That event dramatically pushed scientists to develop new methods to monitor the seafloor venting activity. Coupling the information from geochemical investigations and data collected during the unrest of volcanic activity, we were able to (a) develop theoretical models to gain a better insight on the submarine hydrothermal system and its relationships with the local volcanic and tectonic structures and (b) to develop a preliminary submarine volcanic hazard assessment connected to the Panarea system (Aeolian Islands). In order to mitigate the potential submarine volcanic hazard, three different scenarios are described here: (1) ordinary hydrothermal venting, (2) gas burst, and (3) volcanic eruption. The experience carried out at Panarea demonstrates that the best way to face any submarine volcanic-hydrothermal hazard is to improve the collection of data in near real-time mode by multidisciplinary seafloor observatories and to combine it with periodical sampling activity
Reduced sleep duration affects body composition, dietary intake and quality of life in obese subjects.
Purpose Sleep duration has emerged as a crucial factor
affecting body weight and feeding behaviour. The aim of
our study was to explore the relationship among sleep
duration, body composition, dietary intake, and quality of
life (QoL) in obese subjects.
Methods Body composition was assessed by DXA.
‘‘Sensewear Armband’’ was used to evaluate sleep duration.
SF-36 questionnaire was used to evaluate quality of
life (QoL). A 3-day dietary record was administered.
Subjects were divided into 2 groups: sleep
duration[and B300 min/day.
Results 137 subjects (105 women and 32 men), age:
49.8 ± 12.4 years, BMI: 38.6 ± 6.7 kg/m2, were enrolled.
Sleep duration was B300 min in 30.6 % of subjects.
Absolute and relative fat mass (FM) (40.5 ± 9 vs.
36.5 ± 9.1 kg; 40.2 ± 4.7 vs. 36.9 ± 5.6 %), and truncal
fat mass (19.2 ± 6.1 vs. 16.6 ± 5 kg; 38.6 ± 5.3 vs.
35.2 ± 5.5 %) were higher in subjects sleeping B300 min
when compared to their counterparts (all p.05),
whereas just a tendency towards a higher BMI was
observed (p = 0.077). Even though energy intake was not
different between groups, subjects sleeping B300 min
reported a higher carbohydrate consumption per day
(51.8 ± 5.1 vs. 48.4 ± 9.2 %, p = 0.038). SF-36 total
score was lower in subjects sleeping B300 min
(34.2 ± 17.8 vs. 41.4 ± 12.9, p = 0.025). Sleep duration
was negatively associated with FM (r = -0.25, p = 0.01)
and SF-36 total score (r = -0.31, p.001). The inverse
association between sleep duration and SF-36 total score
was confirmed by the regression analysis after adjustment
for BMI and fat mass (R = 0.43, R2 = 0.19, p = 0.012).
Conclusion Reduced sleep duration negatively influences
body composition, macronutrient intake, and QoL in obese
subjects
Left ventricular mass and intrarenal arterial stiffness as early diagnostic markers in cardiorenal syndrome type 5 due to systemic sclerosis
Background: Cardiorenal syndrome type 5 (CRS-5) includes a group of conditions characterized by a simultaneous involvement of the heart and kidney in the course of a systemic disease. Systemic sclerosis (SSc) is frequently involved in the etiology of acute and chronic CRS-5 among connective tissue diseases. In SSc patients, left ventricular mass (LVM) can be used as a marker of nutritional status and fibrosis, while altered intrarenal hemodynamic parameters are suggestive of early kidney involvement. Methods: Forty-two consecutive patients with a diagnosis of SSc without cardiac and/or renal impairment were enrolled to assess whether cardiac muscle mass can be related to arterial stiffness. Thirty subjects matched for age and sex were also enrolled as healthy controls (HC). All patients performed echocardiography and renal ultrasound. Results: Doppler indices of intrarenal stiffness and echocardiographic indices of LVM were significantly increased in SSc patients compared to HC. A positive correlation exists between LVM/body surface area and pulsatile index (p < 0.05, r = 0.36), resistive index (p < 0.05, r = 0.33) and systolic/diastolic ratio (p < 0.05, r = 0.38). Doppler indices of intrarenal stiffness and LVM indices were significantly higher in SSc patients with digital ulcers than in SSc patients without a digital ulcer history. Conclusions: SSc is characterized by the presence of microvascular and multiorgan injury. An early cardiac and renal impairment is very common. LVM and intrarenal arterial stiffness can be considered as early markers of CRS onset. The clinical use of these markers permits a prompt identification of organ damage. An early diagnosis allows the appropriate setting of pharmacological management, by slowing disease progression
How typhoons trigger turbidity currents in submarine canyons
Intense turbidity currents occur in the Malaylay Submarine Canyon off the northern coast of Mindoro Island in the Philippines. They start in very shallow waters at the shelf break and reach deeper waters where a gas pipeline is located. The pipeline was displaced by a turbidity current in 2006 and its rock berm damaged by another 10 years later. Here we propose that they are triggered near the mouth of the Malaylay and Baco rivers by direct sediment resuspension in the shallow shelf and transport to the canyon heads by typhoon-induced waves and currents. We show these rivers are unlikely to generate hyperpycnal flows and trigger turbidity currents by themselves. Characteristic signatures of turbidity currents, in the form of bed shear stress obtained by numerical simulations, match observed erosion/deposition and rock berm damage patterns recorded by repeat bathymetric surveys before and after typhoon Nock-ten in December 2016. Our analysis predicts a larger turbidity current triggered by typhoon Durian in 2006; and reveals the reason for the lack of any significant turbidity current associated with typhoon Melor in December 2015. Key factors to assess turbidity current initiation are typhoon proximity, strength, and synchronicity of typhoon induced waves and currents. Using data from a 66-year hindcast we estimate a ~8-year return period of typhoons with capacity to trigger large turbidity currents
reduction in heart rate variability in autosomal dominant polycystic kidney disease
Introduction: Cardiovascular disease is one of the main causes of morbidity and mortality in patients with autosomal dominant polycystic kidney disease (ADPKD). Autonomic dysfunction is associated with an increased risk for all cardiovascular events in the general population and can be evaluated with heart rate variability (HRV). Objective: To evaluate HRV in ADPKD patients with mild hypertension versus hypertensive patients with organ damage and healthy controls (HC). Materials and Methods: We have enrolled 65 patients: 21 ADPKD patients (10 males), 20 patients with hypertension (14 males), and 24 HC (10 males). Biochemical analysis, clinical evaluation, anthropometric data, intima-media thickness, 24-h ECG Holter recording, and echocardiography were investigated at the time of enrollment. Results: No significant differences in HRV parameters were found between ADPKD with mild hypertension and hypertensive patients with organ damage. The median of HRV variables in time domain as SDNN (global autonomic activity) was significantly lower in ADPKD and hypertensive patients than HC (p < 0.05). In the frequency domain analysis, low frequency (LF), which mainly reflects the sympathetic component, showed higher values in ADPKD and hypertensive patients than HC during the night (p < 0.01). During the night, the sympathovagal balance, LF/high frequency (HF), showed higher values in ADPKD and hypertensive patients than HC (p < 0.0001). Conversely, LF day was lower in ADPKD and hypertensive patients than HC (p < 0.01). HF, which mainly reflects the parasympathetic component, was lower in ADPKD and hypertensive patients during the night than HC (p < 0.0001). Conclusions: HRV reduction is present in ADPKD patients with mild hypertension in the absence of organ damage. The evaluation of sympathovagal balance can provide novel information on the cardiovascular risk in ADPKD patients in addition to classical risk factors
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