A novel method for validating multi-classifiers. A case study for ICF-based health status classification

In this paper, we propose a novel method for the validation of a multi-classification model according to the intended use and aim of a device for health status classification and the clinical needs of the practitioners involved

Statistical analysis and modeling of intermittent transport events in the tokamak SOL

The turbulence observed in the scrape-off-layer of a tokamak is often characterized by intermittent events of bursty nature, a feature which raises concerns about the prediction of heat loads on the physical boundaries of the device. It appears thus necessary to delve into the statistical properties of turbulent physical fields such as density, electrostatic potential and temperature, focusing on the mathematical expression of tails of the probability distribution functions. The method followed here is to generate statistical information from time-traces of the plasma density stemming from Braginskii-type fluid simulations, and check this against a first-principles theoretical model. The analysis of the numerical simulations indicates that the probability distribution function of the intermittent process contains strong exponential tails, as predicted by the analytical theory.Comment: 16 pages, 8 figure

Variety seeking behavior in the wine domain: A consumers segmentation using big data

This study investigates variety seeking behavior in the wine domain. Since variety seeking depends on brand strategies and consumers’ preferences for different types of vines and denominations, a bi-dimensional perspective is adopted. Two new variety seeking measures are defined, namely the Wine Index of Diversity and Brand Index of Diversity. A finite mixture regression model is implemented to identify and characterize groups of households sharing similar variety seeking behavior in a statistically representative sample of 8,313 Italian households. Four groups are identified based on consumer characteristics and their purchasing behavior. The largest group is “switchers,” which includes consumers showing a relatively higher wine diversity than brand diversity. Estimates reveal the “habitual” group, that lives in the southern Italy and consumes wine less frequently than all other groups. The “loyal” group includes the youngest consumers with an above average income, who reside in the northern regions. Finally, the “variety seekers” are older, have the highest incomes, and live in the central regions. This grouping provides insights into the effects of brand and wine typology on consumers’ choices

Momentum transport in TCV across sawteeth events

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Physics-Based Mixed-Mode Reverse Recovery Modeling And Optimization Of Si PiN And MPS Fast Recovery Diodes

The paper presents the results of the application of physics-based mixed-mode simulations to the analysis and optimization of the reverse recovery for Si-based fast recovery diodes (FREDs) using Platinum (Pt) lifetime killing. The trap model parameters are extracted from Deep Level Transient Spectroscopy (DLTS) characterization. The model is validated against experimental characterization carried out on the current International Rectifier (IR) FRED PiN technology. Improved designs, using emitter control efficiency and merged PiN-Schottky structures, are analyzed. Comparison between simulated and measured results are presente

X-Point Effect on Plasma Blob Dynamics

Plasma blob dynamics on the high-field side in the proximity of a magnetic field null (X point) is investigated in TORPEX. A significant acceleration of the blobs towards the X point is observed. Close to the X point the blobs break apart. The E x B drifts associated with the blobs are measured, isolating the background drift component from the fluctuating contribution of the blob internal potential dipole. The time evolution of the latter is consistent with the fast blob dynamics. An analytical model based on charge conservation is derived for the potential dipole, including ion polarization, diamagnetic, and parallel currents. In the vicinity of the X point, a crucial role in determining the blob motion is played by the decrease of the poloidal magnetic field intensity. This variation increases the connection length that short circuits the potential dipole of the blob. Good quantitative agreement is found between the model and the experimental data in the initial accelerating phase of the blob dynamics

Meandering particle bunches and a link between averages of time series of particle counts and higher-order moments

Time-averaged spatially resolved measurements are used in many fields of physics to determine spatial distributions of a physical quantity. Although one could think that time averaging suppresses all information on time variation, there are some situations in which a link can be established between time averaging and time variability. In this paper, we consider a simple system composed of a particle bunch that moves in space without deforming, and a detector placed at a point in space. The detector continuously counts the number of particles in its neighborhood. Upon sampling, the detector signal gives rise to a time series with, in general, nonvanishing variance. Time series obtained by placing the detector at different locations can then be used to obtain a time-average distribution of the number of particles by computing the time average of all the time series. We show that there is a close relationship between this average profile and higher-order statistics of the time series, including the variance and skewness. We also show a simple procedure by which individual time series can be used to determine features of the shape of the particle bunch

Blob properties in full-turbulence simulations of the TCV scrape-off layer

To investigate blob properties in the tokamak scrape-off layer (SOL), we perform dedicated numerical nonlinear simulations of plasma turbulence in the SOL of a TCV discharge using the Global Braginskii Solver code. A blob detection technique is used for the first time in a three-dimensional (3D) full-turbulence simulation to track the motion of the filaments in the SOL. The specific size, density amplitude and radial velocity of the blobs are computed, with the typical values being 7.4 rho(s), 0.33 n(e) and 0.016 c(s), respectively. The analysis of blob structure in the parallel direction shows that the blobs are partially detached from the limiter. The cross correlation analysis shows how the blobs are born all along the entire field line, not being generated primarily on the low field side SOL and expanding towards the limiter. The blob radial velocity agrees well with the inertial branch of the existing scaling law. The radial particle and heat fluxes given by blobs are shown to be responsible of up to 100% and 70% of the turbulent particle and heat flux in the far SOL, respectively. The results of a second simulation with a 40 times higher resistivity are also discussed

Approaching the investigation of plasma turbulence through a rigorous verification and validation procedure: A practical examplea)

In the present work, a Verification and Validation procedure is presented and applied showing, through a practical example, how it can contribute to advancing our physics understanding of plasma turbulence. Bridging the gap between plasma physics and other scientific domains, in particular, the computational fluid dynamics community, a rigorous methodology for the verification of a plasma simulation code is presented, based on the method of manufactured solutions. This methodology assesses that the model equations are correctly solved, within the order of accuracy of the numerical scheme. The technique to carry out a solution verification is described to provide a rigorous estimate of the uncertainty affecting the numerical results. A methodology for plasma turbulence code validation is also discussed, focusing on quantitative assessment of the agreement between experiments and simulations. The Verification and Validation methodology is then applied to the study of plasma turbulence in the basic plasma physics experiment TORPEX [Fasoli et al., Phys. Plasmas 13, 055902 (2006)], considering both two-dimensional and three-dimensional simulations carried out with the GBS code [Ricci et al., Plasma Phys. Controlled Fusion 54, 124047 (2012)]. The validation procedure allows progress in the understanding of the turbulent dynamics in TORPEX, by pinpointing the presence of a turbulent regime transition, due to the competition between the resistive and ideal interchange instabilities

Synergistic Antibacterial Effects of Metallic Nanoparticle Combinations

© The Author(s) 2019.Metallic nanoparticles have unique antimicrobial properties that make them suitable for use within medical and pharmaceutical devices to prevent the spread of infection in healthcare. The use of nanoparticles in healthcare is on the increase with silver being used in many devices. However, not all metallic nanoparticles can target and kill all disease-causing bacteria. To overcome this, a combination of several different metallic nanoparticles were used in this study to compare effects of multiple metallic nanoparticles when in combination than when used singly, as single elemental nanoparticles (SENPs), against two common hospital acquired pathogens (Staphylococcus aureus and Pseudomonas. aeruginosa). Flow cytometry LIVE/DEAD assay was used to determine rates of cell death within a bacterial population when exposed to the nanoparticles. Results were analysed using linear models to compare effectiveness of three different metallic nanoparticles, tungsten carbide (WC), silver (Ag) and copper (Cu), in combination and separately. Results show that when the nanoparticles are placed in combination (NPCs), antimicrobial effects significantly increase than when compared with SENPs (P < 0.01). This study demonstrates that certain metallic nanoparticles can be used in combination to improve the antimicrobial efficiency in destroying morphologically distinct pathogens within the healthcare and pharmaceutical industry.Peer reviewe