Miracle-dz/UniFAR-FTUs huggingface dataset:
Pulse inversion Doppler: a new method for detecting nonlinear echoes from microbubble contrast agents

A novel technique for the selective detection of ultrasound contrast agents, called pulse inversion Doppler, has been developed. In this technique, a conventional Doppler pulse sequence is modified by inverting every second transmit pulse. Either conventional or harmonic Doppler processing is then performed on the received echoes. In the resulting Doppler spectra, Doppler shifts from linear and nonlinear scattering are separated into two distinct regions which can be analyzed separately or combined to estimate the ratio of nonlinear to linear scattering from a region of tissue. The maximum Doppler shift which can be detected is 1/2 the normal Nyquist limit. In vitro measurements comparing flowing agent and cellulose particles suggest that pulse inversion Doppler can provide 3 to 10 dB more agent to tissue contrast than harmonic imaging with similar pulses. Similar measurements suggest that broadband pulse inversion Doppler can provide up to 16 dB more contrast than broadband conventional Doppler.
Terminology, Emphasis, and Utility in Validation

Lissitz and Samuelsen (2007) have proposed an operational definition of validity that shifts many of the questions traditionally considered under validity to a separate category associated with the utility of test use. Operational definitions support inferences about how well people perform some kind of task or how they respond to some kind of stimulus. Such interpretations can be useful for some purposes, but they do not support any richer interpretations of scores. The author argues that validation should involve an evaluation of the proposed interpretations and uses of test scores. Test developers may choose to adopt a narrow operational interpretation of test scores, but if they do so, they should label the test accordingly.
Enhancing the absolute instability of a boundary layer by adding a far-away plate

When a solid plate, with a boundary condition of no normal flow through it, is introduced parallel to a shear layer it is normally expected to exert a stabilizing influence on any inviscid linearly unstable waves. In this paper we present an example of an absolutely unstable boundary-layer flow that can be made more absolutely unstable by the addition of a plate parallel to the original flow and far from the boundary layer itself. In particular, the addition of the plate is found to increase the growth rate of the absolute instability of the original boundary-layer flow by an order of magnitude for long waves. This phenomenon is illustrated using piecewise-linear inviscid basic-flow profiles, for which analytical dispersion relations have been derived. Long-wave stability theories have been developed in several limits clarifying the mechanisms underlying the behaviour and establishing its generic nature. The class of flows expected to exhibit this phenomenon includes a class found recently to have an exponential growth of disturbances in the wall-normal direction, owing to the approach of certain saddle-points to certain branch-cuts in the complex-wavenumber plane. The theory also suggests that a convectively unstable flow in an infinite domain can be converted, in some circumstances, into an absolutely unstable flow when the domain is made finite by the addition of a plate, however far away the plate is.
Polynomial transform computation of the 2-D DCT

A 2-D DCT (discrete cosine transform) algorithm based on a direct polynomial approach is presented. The resulting algorithm reduces the number of both multiplications and additions compared to previous algorithms. It is shown that, although being mathematically involved, it possesses a clean, butterfly-based structure. Tables comparing the number of operations are provided, as well as flowgraphs. <<ETX>>
On Geometric Hashing and the Generalized Hough Transform

The generalized Hough transform and geometric hashing are two contemporary paradigms for model-based object recognition. Both schemes simultaneously find instances of objects in a scene and determine the location and orientation of these instances. The methods encode the models for the objects in a similar fashion and object recognition is achieved by image features "voting" for object models. For both schemes, the object recognition time is largely independent of the number of objects that are encoded in the object-model database. This paper puts the two schemes in perspective and examines differences and similarities. The authors also study object representation techniques and discuss how object representations are used for object recognition and position estimation. >
On uniqueness in dynamic poroelasticity

Conditions are derived sufficient for uniqueness of solution of the field equations of Biot's theory of liquid-filled porous media, particular attention being paid to continuity requirements at an interface between two such dissimilar materials. It is found that at an interface two distinct sets of conditions will satisfy the demands of the mathematical uniqueness theorem, one of them being discarded on physical grounds. The permissible set is then discussed in relation to a number of possible models of the structure of a pair of elements in contact. The special cases of an impermeable elastic solid or a liquid medium in contact with a saturated porous solid are also examined.
Interaction fluide-structure par la méthode des éléments spectraux

We elaborate in this thesis the numerical simulation of the fluid-structure interaction by the spectral element method. To this end we consider the Navier-Stokes equations for a viscous Newtonian incompressible fluid with an elastic solid the movement of which being described by the equations of the dynamics. The arbitrary Lagrangian Eulerian (ALE) formulation is introduced in the fluid governing equations to deal with the structure movement that is described in Lagrangian representation. The geometrical motion in each domain is built up by the mesh deformation. The space-time discretization of the full mathematical model rests upon the spectral element method. The solid is discretized in the space of polynomials of degree N, PN, while the fluid uses the PN - PN-2 approach. The efficiency of the ALE formulation is tested and validated through various applications. The full algorithm is based on a particular case of the staggered method. The simplified case of a solid immersed in a plane channel closes the thesis. It is then possible to draw the conclusions about the pros and cons of the proposed methodology.
Bayesian Selection on the Number of Factors in a Factor Analysis Model

This paper considers a Bayesian approach for selecting the number of factors in a factor analysis model with continuous and polvtomous variables. A procedure for computing the important statistic in model selection, namely the Bayes factor, is developed via path sampling. The main computation effort is on simulating observations from the appropriate posterior distribution. This task is done by a hybrid algorithm which combines the Gibbs sampler and the Metropolis-Hastings algorithm. Bayesian estimates of thresholds, factor loadings, unique variances, and latent factor scores as well as their standard errors can be produced as by-products. The empirical performance of the proposed procedure is illustrated by means of a simulation study and a real example.
Defect complexes in fluorine-implanted germanium

In the present article we employ positron annihilation lifetime spectroscopy and secondary ion mass spectrometry to study the thermal evolution of vacancy related defects in fluorine-implanted germanium. We find that fluorine enriches the germanium matrix with various vacancy-like clusters that show both concentration and annealing temperature-dependent behaviour. We demonstrate that low fluorine concentrations saturate the Ge matrix with large concentrations of divacancy-like complexes that are effectively removed after moderate annealing. High fluorine concentrations, however, appear to stabilize a large component of monovacancy-like complexes in the near-surface region of the Ge substrates. These monovacancy-like complexes also appear to be thermodynamically stable, even after high-temperature annealing. The nucleation and thermal evolution of these vacancy-like defects may have particular importance in the fabrication and control of future germanium electronic devices.
Evaluation of the ‘take time to think’ safer gambling message: a randomised, online experimental study

In October 2021, a majority of the UK gambling industry implemented a new UK safer gambling message, ‘take time to think’, which features on gambling advertising and websites. An effective safer gambling message could plausibly affect several relevant gambling behaviours, with previous research suggesting that message effectiveness is maximised via messages that are displayed prominently immediately prior to gambling. We experimentally tested this message's effect on four contemporaneous gambling behaviours (the proportion of available funds bet, clicks for help service information, the mean speed of play, and the total number of roulette spins made) in an incentivised online roulette game in a sample of UK-based online gamblers. Participants (n = 2,305) were randomly allocated to either (a) ‘no-message’ control, (b) ‘message’ shown throughout the condition or (c) a ‘message+’ condition, where the message was shown throughout and also via a popup immediately prior to the roulette game. Overall, the results showed no credible effects across the four outcome measures when comparing either of the message conditions to the no-message control. Even the prominent display of the ‘take time to think’ message did not lead to credible beneficial effects on a range of contemporaneous gambling behaviours.
Evaluation of Health Literacy in Plastic Surgery Using a Crowdsourced Patient Survey

Background: Little is known about the levels of health literacy (HL) among plastic and reconstructive surgery (PRS) patients compared with the general population. This study aimed to characterize HL levels in patients interested in plastic surgery and identify potential risk factors associated with inadequate levels of HL among this population. Methods: Amazon’s Mechanical Turk was used to distribute a survey. The Chew’s Brief Health Literacy Screener was used to evaluate the level of HL. The cohort was divided into two groups: non-PRS and PRS groups. Four subgroups were created: cosmetic, noncosmetic, reconstructive, and nonreconstructive groups. A multivariable logistic regression model was constructed to assess associations between levels of HL and sociodemographic characteristics. Results: A total of 510 responses were analyzed in this study. Of those, 34% of participants belong to the PRS group and 66% to the non-PRS group. Inadequate levels of HL were evidenced in 52% and 50% of the participants in the non-PRS and PRS groups, respectively (P = 0.780). No difference in HL levels was found in the noncosmetic versus cosmetic groups (P = 0.783). A statistically significant difference in HL levels was evidenced between nonreconstructive versus reconstructive groups after holding other sociodemographic factors constant (0.29, OR; 95% CI, 0.15–0.58; P < 0.001). Conclusions: Inadequate levels of HL were present in almost half of the cohort, which highlights the importance of adequately assessing HL levels in all patients. It is of utmost importance to evaluate HL in clinical practice using evidence-based criteria to better inform and educate patients interested in plastic surgery.
Experimental and numerical investigation of the interaction of 1 the first four SH guided wave modes with symmetric and non- 2 symmetric discontinuities in plates 3

—The interaction of the SH0, SH1, SH2 and SH3 guided wave modes on a 11 metal plate with a thickness discontinuity is numerically and experimentally investigated. 12 Two different geometries were evaluated, namely symmetric and non-symmetric 13 discontinuities, relative to the plate longitudinal mid-plane. Experiments were performed 14 with periodic permanent magnet array EMATs as transmitters and receivers. Mode 15 separation in transmission and reception was experimentally and numerically performed 16 by dual transduction and by modal decomposition post-processing techniques, 17 respectively. The reflection and transmission coefficients at the discontinuity for each of 18 the investigated SH modes was calculated. It has been experimentally confirmed that 19 when interacting with symmetric discontinuities, only modes that share the same 20 symmetry as the incident mode are created by mode conversion, whereas mode 21 conversion to modes of different symmetry can occur with non-symmetric discontinuities. 22 Experimental and numerical data show good agreement, revealing that the higher the 23 order of the incident mode, the more complex the behaviour of the reflection coefficient 24 is, as a function of the discontinuity depth. For the same incident mode, symmetric 25 discontinuities impose less complexity than non-symmetric ones.
Local stability of an SIR epidemic model and effect of time delay

We describe an SIR epidemic model with a discrete time lag, analyse the local stability of its equilibria as well as the effects of delay on the reproduction number and on the dynamical behaviour of the system. The model has two equilibria—a necessary condition for local asymptotic stability is given. The proofs are based on linearization and the application of Lyapunov functional approach. An upper bound of the critical time delay for which the model remains valid is derived. Numerical simulations are carried out to illustrate the effect of time delay which tends to reduce the epidemic threshold. Copyright © 2009 John Wiley & Sons, Ltd.
Development of Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model

In this paper an overview is given of the development of a new nowcast prediction of aircrew radiation exposure from both background galactic cosmic rays (GCR) and solar energetic particle events (SEP) that may accompany solar storms. The new air-crew radiation exposure model is called the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model. NAIRAS will provide global, data-driven, real-time radiation exposure predictions of biologically harmful radiation at commercial airline altitudes. Observations are utilized from the ground (neutron monitors), from the atmosphere (the NCEP Reanalysis and NCEP Global Forecasting System), and from space (NASA/ACE and NOAA/GOES). Atmospheric observations provide the overhead shielding information and the ground- and space-based observations provide boundary conditions on the incident GCR and SEP particle flux distributions for transport and dosimetry simulations. Exposure rates are calculated using the physics-based HZETRN (High Charge and Energy Transport) code. Recent progress in the model implementation is reported and examples of the model results are shown for a representative high-energy SEP event during the Halloween 2003 superstorm, with emphasis on the high-latitude and polar region. The suppression of the geomagnetic cutoff rigidity during these storm periods and their subsequent influence on atmospheric radiation exposure is characterized. 1.0 System Architecture In its first year of performance, using rapid-prototyping methods, Space Environment Technologies (SET) has used team member (stake-holder) participation to identify the critical input data streams. As a result, the NAIRAS high-level design architecture
A new autoregressive spectrum analysis algorithm

A new recursive algorithm for autoregressive (AR) spectral estimation is introduced, based on the least squares solution for the AR parameters using forward and backward linear prediction. The algorithm has computational complexity proportional to the process order squared, comparable to that of the popular Burg algorithm. The computational efficiency is obtained by exploiting the structure of the least squares normal matrix equation, which may be decomposed into products of Toeplitz matrices. AR spectra generated by the new algorithm have improved performance over AR spectra generated by the Burg algorithm. These improvements include less bias in the frequency estimate of spectral components, reduced variance in frequency estimates over an ensemble of spectra, and absence of observed spectral line splitting.
Solving a Location, Allocation, and Capacity Planning Problem with Dynamic Demand and Response Time Service Level

Logistic systems with uncertain demand, travel time, and on-site processing time are studied here where sequential trip travel is allowed. The relationship between three levels of decisions: facility location, demand allocation, and resource capacity (number of service units), satisfying the response time requirement, is analysed. The problem is formulated as a stochastic mixed integer program. A simulation-based hybrid heuristic is developed to solve the dynamic problem under different response time service level. An initial solution is obtained from solving static location-allocation models, followed by iterative improvement of the three levels of decisions by ejection, reinsertion procedure with memory of feasible and infeasible service regions. Results indicate that a higher response time service level could be achieved by allocating a given resource under an appropriate decentralized policy. Given a response time requirement, the general trend is that the minimum total capacity initially decreases with more facilities. During this stage, variability in travel time has more impact on capacity than variability in demand arrivals. Thereafter, the total capacity remains stable and then gradually increases. When service level requirement is high, the dynamic dispatch based on first-come-first-serve rule requires smaller capacity than the one by nearest-neighbour rule.
Dynamo action in complex flows: the quick and the fast

We consider the kinematic dynamo problem for a velocity field consisting of a mixture of turbulence and coherent structures. For these flows the dynamo growth rate is determined by a competition between the large flow structures that have large magnetic Reynolds number but long turnover times and the small ones that have low magnetic Reynolds number but short turnover times. We introduce the concept of a quick dynamo as one that reaches its maximum growth rate in some (small) neighbourhood of its critical magnetic Reynolds number. We argue that if the coherent structures are quick dynamos, the overall dynamo growth rate can be predicted by looking at those flow structures that have spatial and temporal scales such that their magnetic Reynolds number is just above critical. We test this idea numerically by studying 2.5-dimensional dynamo action which allows extreme parameter values to be considered. The required velocities, consisting of a mixture of turbulence with a given spectrum and long-lived vortices (coherent structures), are obtained by solving the active scalar equations. By using spectral filtering we demonstrate that the scales responsible for dynamo action are consistent with those predicted by the theory.
Using Partially Labeled Data For Normal Mixture Identification With Application To Class Definition

In this paper, we address the problem of estimating the parameters of a normal mixture density when in addition to the unlabeled samples, sets of partially labeled samples are available.We model the density of the multi-dimensional feature space with a normal mixture and assume that the set of components of the mixture can be partitioned into several classes and that training samples are available from each class. Each class can contain one or more components. Since for any training sample the class of origin is known but the exact component of origin within the corresponding class is unknown, we refer to the training samples as partially labeled. We have derived the EM iterative equations for estimating the parameters of the normal mixture in presence of partially labeled samples. These equations can be used to combine the supervised and non-supervised learning processes.
Modeled Variance in Two-Level Models

The concept of explained proportion of variance or modeled proportion of variance is reviewed in the situation of the random effects hierarchical two-level model. It is argued that the proportional reduction in (estimated) variance components is not an attractive parameter to represent the joint importance of the explanatory (independent) variables for modeling the dependent variable. It is preferable instead to work with the proportional reduction in mean squared prediction error for predicting individual values (for the modeled variance at level 1) and the proportional reduction in mean squared prediction error for predicting group averages (for the modeled variance at level 2). It is shown that when predictors are added, the proportion of modeled variance defined in this way cannot go down in the population if the model is correctly specified, but can go down in a sample; the latter situation then points to the possibility of misspecification. This provides a diagnostic means for identifying misspecification.
Numerical analysis of Rayleigh–Plesset equation for cavitating water jets

High‐pressure water jets are used to cut and drill into rocks by generating cavitating water bubbles in the jet which collapse on the surface of the rock target material. The dynamics of submerged bubbles depends strongly on the surrounding pressure, temperature and liquid surface tension. The Rayleigh–Plesset (RF) equation governs the dynamic growth and collapse of a bubble under various pressure and temperature conditions. A numerical finite difference model is established for simulating the process of growth, collapse and rebound of a cavitation bubble travelling along the flow through a nozzle producing a cavitating water jet. A variable time‐step technique is applied to solve the highly non‐linear second‐order differential equation. This technique, which emerged after testing four finite difference schemes (Euler, central, modified Euler and Runge–Kutta–Fehlberg (RKF)), successfully solves the Rayleigh–Plesset (RP) equation for wide ranges of pressure variation and bubble initial sizes and saves considerable computing time. Inputs for this model are the pressure and velocity data obtained from a CFD (computational fluid dynamics) analysis of the jet. Copyright © 2007 John Wiley & Sons, Ltd.
Heteroscedastic Extended Logistic Regression for Postprocessing of Ensemble Guidance

AbstractTo achieve well-calibrated probabilistic forecasts, ensemble forecasts are often statistically postprocessed. One recent ensemble-calibration method is extended logistic regression, which extends the popular logistic regression to yield full probability distribution forecasts. Although the purpose of this method is to postprocess ensemble forecasts, usually only the ensemble mean is used as the predictor variable, whereas the ensemble spread is neglected because it does not improve the forecasts. In this study it is shown that when simply used as an ordinary predictor variable in extended logistic regression, the ensemble spread affects the location but not the variance of the predictive distribution. Uncertainty information contained in the ensemble spread is therefore not utilized appropriately. To solve this drawback a new approach is proposed where the ensemble spread is directly used to predict the dispersion of the predictive distribution. With wind speed data and ensemble forecasts from the.