454 research outputs found

    Time resolved PIV measurements of the unsteady wake migration in a LPT blade passage: effect of the wake passing frequency

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    A time resolved Particle Image Velocimetry (TR-PIV) system has been employed to investigate the unsteady propagation of upstream wakes in a low-pressure turbine cascade. Data are obtained in the steady state condition and for two passing wake reduced frequencies. The study is focused on the identification and split of the different dynamics responsible for deterministic and random oscillations, thus loss generation. A very large data set has been collected: for each condition, about 9000 instantaneous flow fields have been acquired at up to 2kHz in order to resolve with great detail the vortex shedding phenomenon characterizing the separation at steady condition as well as the propagation of the coherent structures induced by the incoming wake. Instantaneous vector maps, phase averaged velocity fields and Proper Orthogonal Decomposition (POD) have been used for the in depth characterization of the different phenomena. The paper takes advantage of the properties of POD that reduces the data set to a low number of modes that represent the most energetic dynamics of the system. It is clearly shown that the phase averaged flow field can be represented by a few number of POD modes related to the wake passing event for the unsteady cases. POD is also able to capture flow features affecting the instantaneous flow field not directly related to the wake passage (i.e. the vortex shedding phenomenon induced by the intermittent separation developing between adjacent wakes), that are smeared out in the phase averaged results. Once recognized the POD modes most involved in the unsteady flow field, a procedure for the quantification of the different contributions to the overall amount of losses is proposed

    Digital tomosynthesis spot view in architectural distortions: outcomes in management and radiation dose

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    Purpose To evaluate if digital breast tomosynthesis spot compression view (DBT-SCV) could be an additional projection to confirm or deny architectural distortions (ADs) detected by digital breast tomosynthesis (DBT) while assessing the average glandular radiation dose. Methods This is a retrospective cohort study enrolling 8864 DBT exams, of which only cases detecting primary AD and with BI-RADS 2-5 score were considered. Seventy-one AD cases examined with DBT-SCV, US and MRI were evaluated for correlation in terms of BI-RADS score; variables among exams were assessed for inter-relationships. Results Of all ADs identified at DBT, biopsy yielded malignancy in only 38%. PPV in identifying malignancy of ADs was higher for DBT-SCV than DBT (p < 0.05); the NPV of DBT-SCV was 94%. The difference between DBT and DBT-SCV in the detection of benign ADs was statistically significant (p < 0.05). AD without US or MRI confirmation was less likely to represent malignancy (p < 0.05). In detecting malignant cases of ADs, both DBT and DBT-SCV were strongly correlated with US and RM (Kappa > 0.90). In identifying benign cases of ADs, DBT-SCV was poorly/moderately correlated with US and RM (Kappa 0.25 and 0.66); DBT was negatively correlated with US and MRI. Conclusion DBT-SCV could be useful to better characterize AD firstly identified by DBT, keeping dose levels within the reference limits. If AD is detected by DBT without an US or MRI correlate, that is not confirmed by DBT-SCV, a "wait and see " approach can be applied to reduce unnecessary biopsy

    Utility of noninvasive methods for the characterization of nonalcoholic liver steatosis in the family practice. The "VARES" Italian multicenter study.

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    The diagnostic utilities of ultrasonography (US), fatty liver index (FLI) and an algorithm of nine serum markers (Fibromax) were evaluated in family practice to noninvasively characterize patients with nonalcoholic fatty liver disease (NAFLD). A multicenter study was conducted by enrolling 259 consecutively observed patients (age 51 ± 10 years) with clinical and ultrasonographic features of NAFLD . Patients had mild (16.2%), moderate (69.9%), or severe (13.9%) liver steatosis and 60.2% had hypertransaminasemia. The percent of patients with overweight, obesity, diabetes, hypertension, and dyslipidemia were 42.7%, 46.5% (4.2% severe obesity), 24.7%, 40.9%, and 56.4% , respectively. Lean patients (10.8%) had normal transaminases in two/ thirds of the cases. A multivariate logistic regression (including age > 50 yrs, BMI > 30 kg/m 2 , HOMA > 3, and hypertransaminasemia) identified 12.3% of patients at risk for steatohepatitis. With a sensitivity of 50% and specificity of 94.7%, Fibromax identified 34 patients (13.1%) with likely advanced fibrosis and found that over 28% of patients with moderate (ultrasonographic) steatosis were likely to be carrying severe steatosis. Steatotest score was significantly associated with BMI, waist circumference, ALT, triglycerides, and FLI. Fibrotest correlated only with ALT. FLI identified 73.4% of patients as likely to be carrying a fatty liver. In conclusion, NAFLD should be systematically searched and characterized in all patients with metabolic disturbances and cardiovascular risk. Asymptomatic subjects at risk also should be screened for NAFLD. Fibromax is a promising noninvasive diagnostic tool in family medicine for identifying patients at risk for NAFLD who require targeted follow-up

    Male factor infertility and assisted reproductive technologies. indications, minimum access criteria and outcomes

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    BackgroundInfertility, which is defined as the inability to conceive after at least 12 months of regular unprotected sexual intercourses, affects about 15-20% of couples worldwide and a male factor is involved in about half of the cases. The development of assisted reproductive technology (ART) made it possible to conceive also to individuals affected from severe oligospermia or azoospermia. However, the impact of the male factor on embryo development, implantation, prevalence of chromosomal abnormalities, genetic and epigenetic alterations, and clinical and obstetric outcomes is still controversial.PurposeThis narrative review examines the indications, minimum access criteria, and outcomes by individual ART technique in relation to the male factor

    Effects of theta on the deuteron binding energy and the triple-alpha process

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    We study the effects that a non zero strong-CP-violating parameter theta would have on the deuteron and diproton binding energies and on the triple-alpha process. Both these systems exhibit fine tuning, so it is plausible that a small change in the nuclear force would produce catastrophic consequences. Such a nuclear force is here understood in the framework of an effective Lagrangian for pions and nucleons, and the strength of the interaction varies with theta. We find that the effects are not too dramatic.Comment: 17 pages, 7 figures, references adde

    Experimental Demonstration of a 5G Network Slice Deployment Exploiting Edge or Cloud Data-Centers

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    This paper has been presented at : Optical Fiber Communications Conference 2019The demo shows the 5G-TRANSFORMER architecture capability to deploy 5G network slices exploiting edge or cloud data-centers in minutes. Different slice deployments are shown to affect the performance of a dictionary mobile-app supported by them.This work has been partially funded by the EU H2020 "5G-Transformer'' Project (grant no. 761536

    Strategies to develop radiomics and machine learning models for lung cancer stage and histology prediction using small data samples

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    Predictive models based on radiomics and machine-learning (ML) need large and annotated datasets for training, often difficult to collect. We designed an operative pipeline for model training to exploit data already available to the scientific community. The aim of this work was to explore the capability of radiomic features in predicting tumor histology and stage in patients with non-small cell lung cancer (NSCLC). We analyzed the radiotherapy planning thoracic CT scans of a proprietary sample of 47 subjects (L-RT) and integrated this dataset with a publicly available set of 130 patients from the MAASTRO NSCLC collection (Lung1). We implemented intra- and inter-sample cross-validation strategies (CV) for evaluating the ML predictive model performances with not so large datasets. We carried out two classification tasks: histology classification (3 classes) and overall stage classification (two classes: stage I and II). In the first task, the best performance was obtained by a Random Forest classifier, once the analysis has been restricted to stage I and II tumors of the Lung1 and L-RT merged dataset (AUC = 0.72 ± 0.11). For the overall stage classification, the best results were obtained when training on Lung1 and testing of L-RT dataset (AUC = 0.72 ± 0.04 for Random Forest and AUC = 0.84 ± 0.03 for linear-kernel Support Vector Machine). According to the classification task to be accomplished and to the heterogeneity of the available dataset(s), different CV strategies have to be explored and compared to make a robust assessment of the potential of a predictive model based on radiomics and ML

    Antimicrobial Effectiveness of Innovative Photocatalysts: A Review

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    Waterborne pathogens represent one of the most widespread environmental concerns. Conventional disinfection methods, including chlorination and UV, pose several operational and environmental problems; namely, formation of potentially hazardous disinfection by-products (DBPs) and high energy consumption. Therefore, there is high demand for effective, low-cost disinfection treatments. Among advanced oxidation processes, the photocatalytic process, a form of green technology, is becoming increasingly attractive. A systematic review was carried out on the synthesis, characterization, toxicity, and antimicrobial performance of innovative engineered photocatalysts. In recent decades, various engineered photocatalysts have been developed to overcome the limits of conventional photocatalysts using different synthesis methods, and these are discussed together with the main parameters influencing the process behaviors. The potential environmental risks of engineered photocatalysts are also addressed, considering the toxicity effects presented in the literature
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