Curvature of a class of indefinite globally framed ff-manifolds

We present a compared analysis of some properties of indefinite almost $\mathcal{S}$-manifolds and indefinite $\mathcal{S}$-manifolds. We give some characterizations in terms of the Levi-Civita connection and of the characteristic vector fields. We study the sectional and ${\phi}$-sectional curvature of indefinite almost $\mathcal{S}$-manifolds and state an expression of the curvature tensor field for the indefinite $\mathcal{S}$-space forms. We analyse the sectional curvature of indefinite $\mathcal{S}$-manifold in which the number of the spacelike characteristic vector fields is equal to that of the timelike characteristic vector fields. Some examples are also described.Comment: 17 pages, no figure

Large eddy simulation of a marine turbine in a stable stratified flow condition

Il presente studio \ue8 incentrato sulla valutazione delle performance e sviluppo della scia di una turbina marina soggetta a condizioni di stratificazione stabile. Lo studio numerico \ue8 stato condotto per mezzo della tecnica di \u2018Large Eddy Simulation\u2019 (LES) mediante l\u2019utilizzo del modello LES-COAST, sviluppato dal gruppo di ricerca. Il modello numerico \ue8 stato validato attraverso la comparazione tra i risultati numerici e dati di laboratorio(reperiti in letteratura) riguardanti la potenza estratta e la forza di thrust generata dalla turbina. Data l\u2019importanza della stratificazione nelle dinamiche marine, l\u2019 obbiettivo \ue8 studiare l\u2019interazione tra la stratificazione e il campo della turbina. Inoltre la produzione globale di un parco di turbine marine e la produzione delle singole turbine possono essere influenzati dagli effetti della stratificazione sul campo di moto. Per quanto riguarda la letteratura, non sono state individuate ricerche con lo scopo di studiare gli effetti della stratificazione sullo sviluppo della scia e della produzione di energia della turbina. I siti di marea nei quali le turbine vengono istallate possono essere soggetti alla presenza di stratificazione stabile di densit\ue0. La stratificazione di densit\ue0 \ue8 causata da variazioni di temperatura e/o salinit\ue0 tra le acque superficiali e le acque del fondo marino. Allo scopo di valutare gli effetti della stratificazione sulla produzione di energia e sul recupero del deficit di velocit\ue0, sono stati simulati due tipi di stratificazione stabile: una condizione intensa e una condizione debole. La stratificazione di tipo debole \ue8 stata simulata imponendo un salto di temperatura in modo da ottenere un profilo di densit\ue0 a forma di gradino. Per quanto riguarda la stratificazione intensa, \ue8 stato imposto un salto di salinit\ue0, anche in questo caso a forma di gradino, il quale produce una maggiore variazione di densit\ue0 rispetto al caso debole. Successivamente la turbina \ue8 stata introdotta all\u2019interno dei due campi stratificati e i conseguenti risultati sono stati comparati. L\u2019analisi dei risultati dimostra che la stratificazione ha un impatto sulla produzione di energia della turbina e sull\u2019evoluzione e recupero della scia. Inoltre l\u2019effetto di mescolamento causato dalla turbina \ue8 stato analizzatoThe present study concerns the evaluation of the effects of stable stratified condition on turbine performance and wake development. The numerical analysis has been carried out by means of Large Eddy simulation (LES) through the in-house LES-COAST model coupled with a turbine module that computes the turbine induced forces. The capability of the model in reproducing power and thrust characteristics of a turbine has been proved from the comparison between the numerical results and the experimental data supplied by literature. Since the stratification is an important factor in the marine dynamics, the aim is to evaluate the interaction between the stratification and the turbine. Moreover the overall power production of a tidal farm and the power output of the single turbines can be influenced by the effects that stratification entails on the flow field. To the best of our knowledge, in the marine field there is no research aimed at studying the influence of marine stratification on wake recover and turbine performance. Tidal sites where marine turbines are installed can be subject to the presence of density stable stratified conditions. The density stratification is due to temperature and/or salinity variations between the superficial and the bottom water. In order to evaluate the influence of stratification on power output and wake development and recover, we simulated to types of stable stratified condition: a weak and a strong stratification. The weak stratification has been simulated imposing a temperature jump in order to obtain a vertical density profile with a step shape. For the strong stratification, we imposed a salinity jump with a step shape which gives rise to an higher density variation compared to the weak case. Then the turbine has been introduced into the stratified fields and the results have been compared. The analysis of the results highlights that the stratification has an impact on turbine production and on wake development and recover. Moreover the turbine mixing effect is analyzed

Default Mode Network alterations in alexithymia: An EEG power spectra and connectivity study

Recent neuroimaging studies have shown that alexithymia is characterized by functional alterations in different brain areas [e.g., posterior cingulate cortex (PCC)], during emotional/social tasks. However, only few data are available about alexithymic cortical networking features during resting state (RS). We have investigated the modifications of electroencephalographic (EEG) power spectra and EEG functional connectivity in the default mode network (DMN) in subjects with alexithymia. Eighteen subjects with alexithymia and eighteen subjects without alexithymia matched for age and gender were enrolled. EEG was recorded during 5 min of RS. EEG analyses were conducted by means of the exact Low Resolution Electric Tomography software (eLORETA). Compared to controls, alexithymic subjects showed a decrease of alpha power in the right PCC. In the connectivity analysis, compared to controls, alexithymic subjects showed a decrease of alpha connectivity between: (i) right anterior cingulate cortex and right PCC, (ii) right frontal lobe and right PCC, and (iii) right parietal lobe and right temporal lobe. Finally, mediation models showed that the association between alexithymia and EEG connectivity values was directed and was not mediated by psychopathology severity. Taken together, our results could reflect the neurophysiological substrate of some core features of alexithymia, such as the impairment in emotional awareness

A novel electromagnetic tracking system for surgery navigation

Objective: This paper proposes the development of a novel electromagnetic tracking system for navigation surgery. Main objective is to provide a system able to operate in a wide tracking volume to make easier and efficient the surgical procedures by assuring high measurement accuracy. Methods: A new field generator consisting in five transmitting coils excited with Frequency Division Multiplexing technique has been developed. Attention is devoted to designing and arrangement of the coils to assure high sensitivity, system scalability and a homogeneous magnetic field inside working volume. A suitable technique based on Look-Up-Table is applied for sensor position calculation and an anthropomorphic robot is used for table calibration. Results: Experimental tests highlight a good repeatability of the measurement data and a negligible noise influence for the proposed system. The obtained tracking volume is wider with respect to the commercial tracking device used in surgical applications and seem promising. Conclusion: The main characteristic of the developed system consists of: scalable and modular configuration of Field Generator, high measured sensitivity due to the increased number of transmitting coils with respect to the classical configuration and large tracking volume. The development of the proposed magnetic tracking systems with high accuracy and wide working volume allows to promote broader utilization of advantaged techniques in surgery procedures for both improving the effectiveness and decreasing the invasiveness of medical interventions

Statin therapy blunts inflammatory activation and improves prognosis and left ventricular performance assessed by Tissue Doppler Imaging in subjects with chronic ischemic heart failure: results from the Daunia Heart Failure Registry

BACKGROUND: A limited number of studies have used Tissue Doppler Imaging (TDI) to evaluate the effect of statin therapy on left ventricular dysfunction in patients with chronic heart failure. In this work, we aimed to determine whether statin administration influenced prognosis, inflammatory activation and myocardial performance evaluated by Tissue Doppler Imaging in subjects enrolled in the Daunia Heart Failure Registry, a local registry of patients with chronic heart failure. METHODS: This study retrospectively analyzed 353 consecutive outpatients with chronic heart failure (mean follow-up 384 days), based on whether statin therapy was used. In all patients, several Tissue Doppler Imaging parameters were measured; circulating levels of interleukin (IL)-6, IL-10 and C-reactive protein were also assayed. RESULTS: Statin administration in 128 subjects with ischemic heart disease was associated with a lower incidence of adverse events (rehospitalization for HF 15% vs. 46%, p<0.001; ventricular arrhythmias 5% vs. 21%, p<0.01; cardiac death 1% vs. 8%, p<0.05), lower circulating levels of IL-6 (p<0.05) and IL-10 (p<0.01), lower rates of chronic heart failure (p<0.001) and better Tissue Doppler Imaging performance (E/E' ratio 12.82 + 5.42 vs. 19.85 + 9.14, p<0.001; ET: 260.62+ 44.16 vs. 227.11 +37.58 ms, p<0.05; TP: 176.79 + 49.93 vs. 136.7 + 37.78 ms, p<0.05 and St: 352.35 + 43.17 vs. 310.67 + 66.46 + 37.78 ms, p<0.05). CONCLUSIONS: Chronic ischemic heart failure outpatients undergoing statin treatment had fewer readmissions for adverse events, blunted inflammatory activation and improved left ventricular performance assessed by Tissue Doppler Imaging

A tool for the automatic calculation of rainfall thresholds for landslide occurrence

Abstract Empirical rainfall thresholds are commonly used to forecast landslide occurrence in wide areas. Thresholds are affected by several uncertainties related to the rainfall and the landslide information accuracy, the reconstruction of the rainfall responsible for the failure, and the method to calculate the thresholds. This limits the use of the thresholds in landslide early warning systems. To face the problem, we developed a comprehensive tool, CTRL–T ( C alculation of T hresholds for R ainfall-induced L andslides− T ool) that automatically and objectively reconstructs rainfall events and the triggering conditions responsible for the failure, and calculates rainfall thresholds at different exceedance probabilities. CTRL−T uses a set of adjustable parameters to account for different morphological and climatic settings. We tested CTRL−T in Liguria region (Italy), which is highly prone to landslides. We expect CTRL−T has an impact on the definition of rainfall thresholds in Italy, and elsewhere, and on the reduction of the risk posed by rainfall-induced landslides

The dry grasslands of Abruzzo National Park, the oldest protected area in the Apennines (Central Italy): overview of vegetation composition, syntaxonomy, ecology and diversity

The Abruzzo, Lazio and Molise National Park was established in 1923 and is considered a flagship conservation area in Italy. It includes large extensions of semi-natural grasslands, maintained by traditional transhumant grazing for centuries. The patterns and drivers of grassland composition within the Park are still poorly investigated, and the scattered phytosociological data available were often based on relevés with varied and not precisely defined sizes. In order to provide for the first time a general overview of the Park’s dry grasslands, we analysed a dataset of 87 relevés with a fixed size of 2 × 2 m, precisely delimited in the field and GPS-located. Specific research aims were: (1) to classify the vegetation plots into floristic-ecological types, supported by an analysis of mean (Italy-specific) Ellenberg Indicator Values (EIVs); (2) to assign the types to up-to-date phytosociological syntaxa; (3) to identify the main environmental drivers for both composition and richness patterns; (4) to test the degree of correlation between (Italy-specific) EIVs and the measured environmental variables. Environmental predictors included high-resolution climatologies and remote-sensed standing biomass. Main vegetation types were identified using Hierarchical Cluster Analysis (HCA). Distancebased RDA was performed as a constrained ordination method to reveal correlations between floristic composition and environmental variables. Drivers of species richness were explored through partial correlation and Regression Trees. HCA and NMDS revealed four floristically and ecologically well-interpretable groups, in turn well corresponding to the level of phytosociological class (namely Molinio-Arrhenatheretea, Nardetea strictae, Festuco hystricis-Ononidetea striatae and Festuco-Brometea). Constrained ordination showed that most of the floristic variation was explained by biomass, annual precipitation (Pann) and mean annual temperature (Tm). Strong and significant positive correlations were found between biomass and EIV for Nitrogen (EIV-N), and between Tm and EIV for Temperature (EIV-T). Strong and significant negative correlations were found between Pann and EIV-T, EIV for Continentality (EIV-C) and EIV for soil Reaction (EIV-R). Species richness was positively correlated with slope inclination and negatively with elevation; richness was higher in sites with a high rock cover, and on limestone or clayey substrata than on siliceous ones. We conclude that in the study area: a) dry semi-natural grasslands are arranged at least into four distinguishable, high rank floristic-ecological groups; b) a mixture of climatic (especially precipitation) and edaphic (especially bedrock and soil reaction) gradients are the main drivers of such composition patterns; c) species richness is higher in sites more stressed by summer drought and/or nutrient scarcity; d) community-means of Italy’s specific EIVs are well correlated with environmental variables in grasslands, including a good correspondence between EIV-T and mean annual temperature