Miracle-dz/UniFAR-FTUs huggingface dataset:
Intermittent contact scanning force microscopy: The role of the liquid necks

We have studied the intermittent contact mode for small oscillation amplitudes and soft cantilevers with sharp tips. For appropriate working conditions the tip does not touch the mica surface. Instead, a high dissipative tip–sample interaction takes place which reduces the oscillation amplitude of the cantilever. Our experiments show that this dissipative interaction is related to the relative humidity and we believe that it is induced by a nanometer sized liquid neck between tip and sample. A phase contrast image on different surface materials is then due mainly to the wetting properties of the corresponding material rather than to their elastic or viscoelastic properties. The intermittent contact mode described in this work is especially advantageous since the tip is extremely gentle with the surface.
A direct numerical simulation study of interface propagation in homogeneous turbulence

A 3D direct numerical simulation (DNS) study of the evolution of a self-propagating interface in forced constant-density statistically stationary homogeneous isotropic turbulence was performed by solving Navier–Stokes and level-set equations under a wide range of conditions that cover various (from 0.1 to 2.0) ratios of the interface speed $S_{L}$ to the r.m.s. turbulent velocity $U^{\prime }$ and various (50, 100 and 200) turbulent Reynolds numbers $\mathit{Re}$ . By analysing computed data, the following issues were addressed: (i) dependence of the speed and thickness of the fully developed statistically planar mean front that envelops the interface on $U^{\prime }/S_{L}$ and $\mathit{Re}$ , (ii) dependence of the fully developed mean turbulent flux of a scalar $c$ that characterizes the state of the fluid ( $c=0$ and 1 ahead and behind the interface respectively) on $U^{\prime }/S_{L}$ and $\mathit{Re}$ , (iii) evolution of the mean front speed, its thickness, and the mean scalar flux during the front development after embedding a planar interface into the forced turbulence and (iv) relation between canonical and conditioned moments of the velocity, velocity gradient and pressure gradient fields.
Model predictions for the WAXS signals of healthy and malignant breast duct biopsies

A wide-angle x-ray scatter (WAXS) measurement could potentially be used to determine whether a biopsy of a breast duct is healthy or malignant. A ductal carcinoma in situ (DCIS) occurs when the epithelial cells lining the wall start to replicate and invade the duct interior. Since cells are composed mainly of water a WAXS signal of DCIS could contain a larger component due to water. A model approximates that a breast duct biopsy consists of connective tissue (c.t.) and cells. For a 2 mm diameter 3.81 mm thick healthy duct biopsy, the volumes in cubic mm are 11.56 c.t. and 0.41 cells whereas 6.64 c.t. and 5.33 cells for DCIS. The differential linear scattering coefficients (μs) for both types of biopsies were calculated using the sum vc.t. μsc.t. + vcellμscell where v denotes fractional volume. The cell was assumed to be composed of water, lipids (fat), and other atoms associated with RNA, DNA, proteins, and carbohydrates. The μscell was calculated using the sum 0. 771μswater + 0. 023μsfat + 0. 206μsother. The μs of c.t. , water, and fat were available from literature whereas the independent atomic model approximation was used to calculate values for μsother. A WAXS model provided predictions of the number of 6 degree scattered photons Ns for incident 50 kV beams on healthy and malignant ducts. The sum of Ns between 31.5 ≤ E ≤ 45 keV were 1402 and 1529 for respectively the healthy and malignant biopsies. Using Poisson statistics, two Gaussian distributions, and a descision threshold set at their intersection, the false positive and false negative probabilities were 4.7% and 5.0%. This work suggests that DCIS could potentially be diagnosed via energy dispersive WAXS measurements.
Mesoscale Impacts of Explicit Numerical Diffusion in a Convection-Permitting Model

AbstractIn convection-permitting simulations, the spectrum of resolved motions is truncated near scales where convection is active. An “energy gap” between resolved and unresolved motions does not exist, such that the upscale and downscale fluxes of energy across the spectrum are affected by the representation of turbulence as well as (implicit and explicit) numerical diffusion. In the current study, a systematic analysis is undertaken of the role of explicit numerical diffusion in simulations of diurnal convection over a large Alpine region, using the Consortium for Small Scale Modeling (COSMO) mesoscale model. Results are explored by using energy spectra and by diagnosing the physical and dynamical contributions to the bulk mesoscale heat budget. In addition, a linear analytical model is employed to assess different formulations of numerical diffusion.Consistent with previous studies the authors find that diffusion may strongly affect the energy spectrum and the formation of precipitation. Besides the d.
A variable temperature cryostat for the thermoluminescence studies

A simple and inexpensive variable-temperature liquid-nitrogen cryostat is described which has been in operation for sample temperature control in the studies on post-irradiation thermoluminescence of biomolecules in the range 77 K to room temperature. Arrangements are incorporated to raise the temperature of the sample chamber from 77 K at a desired rate by varying the electrical input to the sample heater. The sample holder can also be stabilized at any temperature between 77 K and room temperature in a short time and maintained at that temperature over long periods of time. Although of simple construction the cryostat is economical of liquid nitrogen and has been found to have many advantages for thermoluminescence investigations.
Active Contour Driven by Edge and Region Image Fitting Energy

In this paper, we propose a novel edge and region-based active contour model. We consider geodesic curve and region-based model, and evolve a contour based on global information. Moreover, we add to the level set regularization term in the energy functional to ensure accurate computation and avoids expensive re-initialization of the level set function. Experiments on synthetic and real images show desirable performances of our method.
Modeling the propagation of solar energetic particles in corotating compression regions of solar wind

[1] We present the first modeling of solar energetic particle (SEP) events inside corotating compression regions. We consider gradual compressions in the interplanetary magnetic field brought on by interaction of the solar wind streams of different speed. The compression model is similar to that previously suggested for the acceleration of low-energy particles associated with corotating interaction regions (CIRs). In the framework of focused transport, we perform Monte Carlo simulations of the SEP propagation, adiabatic deceleration and reacceleration. A trap-like structure of the interplanetary magnetic field modifies the SEP intensity-time profiles, energy spectra, and anisotropy. Particle diffusion and adiabatic deceleration are typically reduced. For this reason, at a corotating vantage point the SEP event development after the intensity maximum is slower than would be expected based on the modeling in the standard, Archimedean spiral field. At the noncorotating spacecraft the magnetic tube convection past the observer becomes more important. The numerical model forms a basis on which to interpret SEP observations made by present and future spacecrafts at the longitude-dependent speed of solar wind. In particular, the modeling results are similar to the patterns observed with the ERNE particle telescope on board SOHO in August 1996. In the proton anisotropy data, we find a signature of the magnetic mirror associated with the CIR. A relation is established between the spectra observed at 1 AU and the SEP injection spectrum near the Sun.
On the effect of the body force on the symmetry breaking in miscible two‐fluid channel flow

The two‐dimensional flow field is numerically investigated using a compact finite difference and a pseudo‐spectral method when two fluids with different physical properties are mixing under gravity as well as flow rate. The gravity and the viscous mobility affect the fingering instability, i.e. the mixing range shrinks much at the large viscous mobility or the strong gravity. When the gravitation acts parallel to the main stream, the flow decelerates or accelerates according to its direction. The fingertip velocity is exactly expressed by a pure cosine function and especially invariant when the gravity acts along the −y direction at the high Peclet number. The maximum and fingertip velocities at the very low Peclet number are nearly symmetric with respect to the −y direction perpendicular to the main flow direction x. When the gravity acts along the −y direction, the flow field shows the asymmetry, and a pair of vortices is generated at both the very high Peclet number and less viscous mobility number. As the viscous mobility becomes large, the vortex scale enlarges at the small Peclet number, while the vortices are slightly destroyed at the relatively high Peclet number. As the gravitational angle changes clockwise from downstream to upstream, a pair of vortices evolves through a process of asymmetry.
A novel As2S5-tellurite hybrid photonic crystal fiber for long mid-IR supercontinuum fiber lasers

We numerically demonstrate the supercontinuum (SC) generation in a novel chalcogenide As2S5 nanowire embeddedcore into Tellurite photonic crystal fiber (PCF). This hybrid As2S5-tellurite small core PCF has a pitch of 0.7 μm and air hole diameter of 0.2 μm. It exhibits a zero dispersion wavelength (ZDW) of 3.25 μm with an overall highly engineered group velocity dispersion (GVD) shifted to the mid-IR wavelengths region. By injecting 100 fs hyperbolic-secant input pulses delivered by available tunable optical parametric oscillator (OPO) system at the pump wavelength of 3.389 μm, we obtain a broadband coherent mid-IR SC generated in only 1 mm-long PCF with a peak power of 8.8 kW. An ultralarge mid-IR bandwidth extending from 1000 to 7200 nm is generated with more than 60% of the total power which is available beyond 3 μm. The proposed hybrid PCF structure shows to be very promising for designing new compact, stable and powerful SC fiber laser sources in the long mid-IR wavelength region.
Perturbation by and recovery from bend curvature of a fully developed turbulent pipe flow

An experimental investigation was carried out to study the perturbation by and recovery from bend curvature of a fully developed turbulent pipe flow. The pipe Reynolds number and the pipe‐to‐bend radius ratio were 50 000 and 0.077, respectively. Hot‐wire techniques were used to measure the three components of mean velocity and the six components of the Reynolds stress along a horizontal as well as along a normal plane in streamwise locations extending from 18 diameters upstream to 18 diameters downstream of the U‐bend. Results show that a Dean‐type secondary motion is established in the bend and is confirmed by a numerical modeling of the flow based on a two‐equation closure. Evidence of a second cell is obtained within the bend and again verified by numerical results and previous total pressure measurements. Therefore it is postulated that the pressure field is also responsible for the second cell. The second cell disappears at about one diameter downstream of the curved bend. Turbulent kinetic energy is.
A Mixed 4-Node 3D Plate Element Based on Self-Equilibrated Isostatic Stresses

A new mixed stress 4-node flat shell finite element, designed for the linear and nonlinear analysis of folded plate structures, is presented. The kinematics of the element is defined by 24 dofs with in- and out-of-plane displacements assumed to be quadratic, controlled by displacement and rotation parameters through an Allman like interpolation, and flexural rotations assumed to be bilinear. The assumed stress approximation, described within a local Cartesian frame aligned with the element orientation, is self-equilibrated and ruled by the minimum number of parameters. The element does not suffer from kinematical locking and rank defectiveness. Many numerical tests show the very good performance of the element.
Collaborative statistical investigations in diverse settings

This study presents a continuing investigation of influences on outcomes achieved by students working in groups of three on tasks related to chance and data. Earlier research described final mathematical outcomes and identified 17 factors influencing three types of short-term outcomes for groups working in an isolated setting. The current report documents the 17 factors for groups working in a classroom setting and 1654 events for all groups in both settings are identified and each associated with a factor and a short-term outcome. Consideration is then given to variables that have the potential to influence the factors, the short-term outcomes, and their interaction. The overarching variable is the setting within which the collaboration took place. Within each setting, however, two other variables operated: the task carried out, the age/grade of students, gender balance, or collaborative characteristics. The influences of these variables are described within the two settings before consideration is given to the overall influence of the settings.
Complex Dynamical Behavior of a Two-Stage Colpitts Oscillator with Magnetically Coupled Inductors

A five-dimensional (5D) controlled two-stage Colpitts oscillator is introduced and analyzed. This new electronic oscillator is constructed by considering the well-known two-stage Colpitts oscillator with two further elements (coupled inductors and variable resistor). In contrast to current approaches based on piecewise linear (PWL) model, we propose a smooth mathematical model (with exponential nonlinearity) to investigate the dynamics of the oscillator. Several issues, such as the basic dynamical behaviour, bifurcation diagrams, Lyapunov exponents, and frequency spectra of the oscillator, are investigated theoretically and numerically by varying a single control resistor. It is found that the oscillator moves from the state of fixed point motion to chaos via the usual paths of period-doubling and interior crisis routes as the single control resistor is monitored. Furthermore, an experimental study of controlled Colpitts oscillator is carried out. An appropriate electronic circuit is proposed for the investigations of the complex dynamics behaviour of the system. A very good qualitative agreement is obtained between the theoretical/numerical and experimental results.
ATEPP: A Dataset of Automatically Transcribed Expressive Piano Performance

Computational models of expressive piano performance rely on attributes like tempo, timing, dynamics and pedalling. Despite some promising models for performance assessment and performance rendering, results are limited by the scale, breadth and uniformity of existing datasets. In this paper, we present ATEPP, a dataset that contains 1000 hours of performances of standard piano repertoire by 49 world-renowned pianists, organized and aligned by compositions and movements for comparative studies. Scores in MusicXML format are also available for around half of the tracks. We first evaluate and verify the use of transcribed MIDI for representing expressive performance with a listening evaluation that involves recent transcription models. Then, the process of sourcing and curating the dataset is outlined, including composition entity resolution and a pipeline for audio matching and solo filtering. Finally, we conduct baseline experiments for performer identification and performance rendering on our dataset, demonstrating its potential in generalizing expressive features of individual performing style.
Minimising expected discounted capital injections by reinsurance in a classical risk model

In this paper we consider a classical continuous time risk model, where the claims are reinsured by some reinsurance with retention level , where means ‘no reinsurance’ and b=0 means ‘full reinsurance’. The insurer can change the retention level continuously. To prevent negative surplus the insurer has to inject additional capital. The problem is to minimise the expected discounted cost over all admissible reinsurance strategies. We show that an optimal reinsurance strategy exists. For some special cases we will be able to give the optimal strategy explicitly. In other cases the method will be illustrated only numerically.
New Numerical Scheme for Pricing American Option with Regime-Switching

This paper is concerned with regime-switching American option pricing. We develop new numerical schemes by extending the penalty method approach and by employing the θ-method. With regime-switching, American option prices satisfy a system of m free boundary value problems, where m is the number of regimes considered for the market. An (optimal) early exercise boundary is associated with each regime. Straightforward implementation of the θ-method would result in a system of nonlinear equations requiring a time-consuming iterative procedure at each time step. To avoid such complications, we implement an implicit approach by explicitly treating the nonlinear terms and/or the linear terms from other regimes, resulting in computationally efficient algorithms. We establish an upper bound condition for the time step size and prove that under the condition the implicit schemes satisfy a discrete version of the positivity constraint for American option values. We compare the implicit schemes with a tree model that generalizes the Cox-Ross-Rubinstein (CRR) binomial tree model, and with an analytical approximation solution for two-regime case due to Buffington and Elliott. Numerical examples demonstrate the accuracy and stability of the new implicit schemes.
Improved three-dimensional optical model for thin-film silicon solar cells

We present an optical model for thin-film silicon solar cells (both single and multijunction) with nanorough surfaces/interfaces. For these cells, the optical absorptance within each layer and the total reflectance are computed taking into account roughness, angular distribution of scattered light, thicknesses, and optical constants of all layers. In the model, we combine coherent approach, scattering theory, and Monte Carlo tracing method. Results of the model are shown to be in good agreement with the experimentally measured spectral response and the total reflectance of solar cells. Some predictions of the ultimate solar cell performance based on the model are presented as well.
Diurnal Variation of Downslope Winds in Owens Valley during the Sierra Rotor Experiment

Abstract The impact of diurnal forcing on a downslope wind event that occurred in Owens Valley in California during the Sierra Rotors Project (SRP) in the spring of 2004 has been examined based on observational analysis and diagnosis of numerical simulations. The observations indicate that while the upstream flow was characterized by persistent westerlies at and above the mountaintop level the cross-valley winds in Owens Valley exhibited strong diurnal variation. The numerical simulations using the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) capture many of the observed salient features and indicate that the in-valley flow evolved among three states during a diurnal cycle. Before sunrise, moderate downslope winds were confined to the western slope of Owens Valley (shallow penetration state). Surface heating after sunrise weakened the downslope winds and mountain waves and eventually led to the decoupling of the well-mixed valley air from the westerlies aloft around local noon (decoupled .
Propagation of laser-generated plasma jet in an ambient medium

In this work we present experimental research related to laboratory astrophysics using an intense laser. The goal of these experiments is to investigate some of the complex features of young stellar objects and astrophysical outflows, in particular the plasma jet interaction with the interstellar medium. The relevance of these experiments to astrophysics is measured through similarity criteria (scaling laws). These ensure the similarity between the astrophysical object and the laboratory provided that the dimensionless numbers are equivalent. Consequently, measurements of the plasma parameters are crucial to link laboratory research to astrophysics as they are needed for the determination of these dimensionless numbers. In this context, we designed experiments to generate plasma jets using an intense laser, and to study the evolution in vacuum and in an ambient medium.
Estimating the Number of Clusters via the GUD Statistic

Estimating the number of clusters is one of the most difficult problems in cluster analysis. Most previous approaches require knowing the data matrix and may not work when only a Euclidean distance matrix is available. Other approaches also suffer from the curse of dimensionality and work poorly in high dimension. In this article, we develop a new statistic, called the GUD statistic, based on the idea of the Gap method, but use the determinant of the pooled within-group scatter matrix instead of the within-cluster sum of squared distances. Some theory is developed to show this statistic can work well when only the Euclidean distance matrix is known. More generally, this statistic can even work for any dissimilarity matrix that satisfies some properties. We also propose a modification for high-dimensional datasets, called the R-GUD statistic, which can give a robust estimation in high-dimensional settings. The simulation shows our method needs less information but is generally found to be more accurate and robust than other methods considered in the study, especially in many difficult settings.
Automatic selection of arterial input function using tri-exponential models

Dynamic Contrast Enhanced MRI (DCE-MRI) is one method for drug and tumor assessment. Selecting a consistent arterial input function (AIF) is necessary to calculate tissue and tumor pharmacokinetic parameters in DCE-MRI. This paper presents an automatic and robust method to select the AIF. The first stage is artery detection and segmentation, where knowledge about artery structure and dynamic signal intensity temporal properties of DCE-MRI is employed. The second stage is AIF model fitting and selection. A tri-exponential model is fitted for every candidate AIF using the Levenberg-Marquardt method, and the best fitted AIF is selected. Our method has been applied in DCE-MRIs of four different body parts: breast, brain, liver and prostate. The success rates in artery segmentation for 19 cases are 89.6%±15.9%. The pharmacokinetic parameters computed from the automatically selected AIFs are highly correlated with those from manually determined AIFs (R2=0.946, P(T<=t)=0.09). Our imaging-based tri-exponential AIF model demonstrated significant improvement over a previously proposed bi-exponential model.
Gain bandwidth of NbN hot-electron bolometer terahertz mixers on 1.5 um Si3N4 /SiO2 membranes

The gain bandwidth of NbN hot-electron bolometer terahertz mixers on electrically thin Si3N4 /SiO2 membranes was experimentally investigated and compared with that of HEB mixers on bulk substrates. A gain bandwidth of 3.5 GHz is achieved on bulk silicon, whereas the gain bandwidth is reduced down to 0.6–0.9 GHz for mixers on 1.5 um Si3 N4 /SiO2 membranes. We show that application of a MgO buffer layer on the membrane extends the gain bandwidth to 3 GHz. The experimental data were analyzed using the film-substrate acoustic mismatch approach.