560 research outputs found

    Uncertainty in river discharge observations: a quantitative analysis

    Get PDF
    Abstract. This study proposes a framework for analysing and quantifying the uncertainty of river flow data. Such uncertainty is often considered to be negligible with respect to other approximations affecting hydrological studies. Actually, given that river discharge data are usually obtained by means of the so-called rating curve method, a number of different sources of error affect the derived observations. These include: errors in measurements of river stage and discharge utilised to parameterise the rating curve, interpolation and extrapolation error of the rating curve, presence of unsteady flow conditions, and seasonal variations of the state of the vegetation (i.e. roughness). This study aims at analysing these sources of uncertainty using an original methodology. The novelty of the proposed framework lies in the estimation of rating curve uncertainty, which is based on hydraulic simulations. These latter are carried out on a reach of the Po River (Italy) by means of a one-dimensional (1-D) hydraulic model code (HEC-RAS). The results of the study show that errors in river flow data are indeed far from negligible

    Evidences of relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

    No full text
    International audienceSeveral hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day are observed at a dense network of raingauges sited in northern central Italy are statistically analyzed using an approach based on L-moments. The study investigates the statistical properties of rainfall extremes and identifies important relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we develop a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The reliability of the regional model is assessed through Monte Carlo simulations. The results are relevant given that the proposed model is able to reproduce the statistical properties of rainfall extremes observed for the study region

    Relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

    Get PDF
    Several hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day, observed at a dense network of raingauges sited in northern central Italy, are analyzed using an approach based on L-moments. The analysis investigates the statistical properties of rainfall extremes and detects significant relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we developed a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The applicability of the regional model was assessed through Monte Carlo simulations. The uncertainty of the model for ungauged sites was quantified through an extensive cross-validation

    Multiple hazards and risk perceptions over time: the availability heuristic in Italy and Sweden under COVID-19

    Get PDF
    The severe impact of global crises, such as COVID-19 and climate change, is plausibly reshaping the way in which people perceive risks. In this paper, we examine and compare how global crises and local disasters influence public perceptions of multiple hazards in Italy and Sweden. To this end, we integrate information about the occurrence of hazardous events with the results of two nationwide surveys. These included more than 4000 participants and were conducted in two different phases of the COVID-19 pandemic corresponding to low (August 2020) and high (November 2020) levels of infection rates. We found that, in both countries, people are more worried about risks related to experienced events. This is in line with the cognitive process known as the availability heuristic: individuals assess the risk associated with a given hazard based on how easily it comes to their mind. Epidemics, for example, are perceived as less likely and more impactful in Italy compared to Sweden. This outcome can be explained by cross-country differences in the impact of, as well as governmental responses to, COVID-19. Notwithstanding the ongoing pandemic, people in both Italy and Sweden are highly concerned about climate change, and they rank it as the most likely threat

    Nordic walking increases circulating VEGF more than traditional walking training in postmenopause.

    Get PDF
    OBJECTIVES Nordic walking (NW) is widely practiced by postmenopausal women. Its effects are peculiar owing to the involvement of more muscle groups than in traditional walking training (WT). Since mechanical load promotes secretion of vascular endothelial growth factor (VEGF) from both skeletal muscle and muscle endothelium, the aim of the study was to compare the effect of NW and WT on VEGF levels. METHOD Thirty postmenopausal women were randomly assigned to NW or WT. Both groups trained 40-50 min/day, three times per week, at a mean intensity of 12 on a 15-category scale of the ratings of perceived exertion. Since VEGF is also released from adipocytes, anthropometric parameters were assessed. RESULTS NW increased circulating VEGF more than WT (p = 0.041). Furthermore, both study groups exhibited an average decrease in weight (p = 0.023), body mass index (p = 0.024), hip circumference (p = 0.001), and arm fat index, although WT participants had higher values for this index at baseline (p < 0.001) and thus exhibited a greater net decrease compared with the NW participants (p < 0.011). CONCLUSIONS These data imply that NW increases the level of circulating VEGF more than does traditional walking when the intensity of training is equivalent

    Electrodynamics near the Metal-to-Insulator Transition in V3O5

    Full text link
    The electrodynamics near the metal-to-insulator transitions (MIT) induced, in V3O5 single crystals, by both temperature (T) and pressure (P) has been studied by infrared spectroscopy. The T- and P-dependence of the optical conductivity may be explained within a polaronic scenario. The insulating phase at ambient T and P corresponds to strongly localized small polarons. Meanwhile the T-induced metallic phase at ambient pressure is related to a liquid of polarons showing incoherent dc transport, in the P-induced metallic phase at room T strongly localized polarons coexist with partially delocalized ones. The electronic spectral weight is almost recovered, in both the T and P induced metallization processes, on an energy scale of 1 eV, thus supporting the key-role of electron-lattice interaction in the V3O5 metal-to-insulator transition.Comment: 7 pages, 5 figure

    Evidence of a pressure-induced metallization process in monoclinic VO2_2

    Full text link
    Raman and combined trasmission and reflectivity mid infrared measurements have been carried out on monoclinic VO2_2 at room temperature over the 0-19 GPa and 0-14 GPa pressure ranges, respectively. The pressure dependence obtained for both lattice dynamics and optical gap shows a remarkable stability of the system up to P*∼\sim10 GPa. Evidence of subtle modifications of V ion arrangements within the monoclinic lattice together with the onset of a metallization process via band gap filling are observed for P>>P*. Differently from ambient pressure, where the VO2_2 metal phase is found only in conjunction with the rutile structure above 340 K, a new room temperature metallic phase coupled to a monoclinic structure appears accessible in the high pressure regime, thus opening to new important queries on the physics of VO2_2.Comment: 5 pages, 3 figure

    Socio-hydrological spaces in the Jamuna River floodplain in Bangladesh

    Get PDF
    Socio-hydrology aims to understand the dynamics and co-evolution of coupled human–water systems, with research consisting of generic models as well as specific case studies. In this paper, we propose a concept to help bridge the gap between these two types of socio-hydrological studies: socio-hydrological spaces (SHSs). A socio-hydrological space is a geographical area in a landscape. Its particular combination of hydrological and social features gives rise to the emergence of distinct interactions and dynamics (patterns) between society and water. Socio-hydrological research on human–flood interactions has found two generic responses, fight or adapt. Distilling the patterns resulting from these responses in case studies provides a promising way to relate contextual specificities to the generic patterns described by conceptual models. Through the use of SHSs, different cases can be compared globally without aspiring to capturing them in a formal model. We illustrate the use of SHS for the Jamuna floodplain, Bangladesh. We use narratives and experiences of local experts and inhabitants to empirically describe and delimit SHS. We corroborated the resulting classification through the statistical analysis of primary data collected for the purpose (household surveys and focus group discussions) and secondary data (statistics, maps etc.). Our example of the use of SHSs shows that the concept draws attention to how historical patterns in the co-evolution of social behaviour, natural processes and technological interventions give rise to different landscapes, different styles of living and different ways of organising livelihoods. This provides a texture to the more generic patterns generated by socio-hydrological models, promising to make the resulting analysis more directly useful for decision makers. We propose that the usefulness of this concept in other floodplains, and for other socio-hydrological systems than floodplains, should be explored.</p

    Cardiomyopathy associated with diabetes. the central role of the cardiomyocyte

    Get PDF
    The term diabetic cardiomyopathy (DCM) labels an abnormal cardiac structure and performance due to intrinsic heart muscle malfunction, independently of other vascular co-morbidity. DCM, accounting for 50%-80% of deaths in diabetic patients, represents a worldwide problem for human health and related economics. Optimal glycemic control is not sufficient to prevent DCM, which derives from heart remodeling and geometrical changes, with both consequences of critical events initially occurring at the cardiomyocyte level. Cardiac cells, under hyperglycemia, very early undergo metabolic abnormalities and contribute to T helper (Th)-driven inflammatory perturbation, behaving as immunoactive units capable of releasing critical biomediators, such as cytokines and chemokines. This paper aims to focus onto the role of cardiomyocytes, no longer considered as "passive" targets but as "active" units participating in the inflammatory dialogue between local and systemic counterparts underlying DCM development and maintenance. Some of the main biomolecular/metabolic/inflammatory processes triggered within cardiac cells by high glucose are overviewed; particular attention is addressed to early inflammatory cytokines and chemokines, representing potential therapeutic targets for a prompt early intervention when no signs or symptoms of DCM are manifesting yet. DCM clinical management still represents a challenge and further translational investigations, including studies at female/male cell level, are warranted

    Different Approaches to the Study of Apoptosis

    Get PDF
    The morphological features of cell undergoing programmed cell death is well known and has been widely described in a number of experimental models with a variety of apoptotic triggering agents. Despite the similar cell behaviour, underlying molecular events seem variable and only partially understood. A multiple approach appears crucial to better clarify the phenomenon. The first technique, DNA gel electrophoresis, allows the identification of fragmented DNA and has been long considered the hallmark of apoptosis. Different patterns of DNA cleavage, which can be identified by conventional or pulsed-field gel electrophoresis, are presented and discussed. In situ labelling methods are also described both with terminal deoxynucleotidyl transferase and DNA polymerase I, aimed at the study of the distribution of DNA cleavage areas. Flow cytometry is also proposed and different technical approaches, based on different laser utilizations, are discussed. Ultrastructural analysis, allowing the study of apoptotic cell details, is finally considered
    • …
    corecore