Miracle-dz/UniFAR-FTUs huggingface dataset:
Measurement of retinal physiology using functional Fourier domain OCT concepts

Fourier Domain OCT proved to be an outstanding tool for measuring 3D retinal structures with high sensitivity, resolution, and speed. We extended the FDOCT concept towards functional imaging by analyzing the spectroscopic tissue properties, polarization contrast and Doppler velocity imaging. Differential spectral contrast FDOCT allows optical staining of retinal tomograms and to contrast tissue of high pigmentation such as the retinal pigment epithelium (RPE). The latter shows strong correlation if compared to polarization sensitive OCT images. First implementations of Doppler FDOCT systems demonstrated the capability of measuring in-vivo retinal blood flow profiles and pulsatility. We developed a new concept of Doppler FDOCT that allows measuring also large flow velocities typically close to the optic nerve head. Studies of retinal perfusion based on Laser Doppler Flowmetry (LDF) demonstrated the high sensitivity of blood flow to external stimuli. We performed first experiments of studying retinal perfusion in response to flicker stimulation. An increase in vessel diameter by 11% and of flow velocity by 49% was measured. We believe that a multi-modal functional imaging concept is of high value for an accurate and early diagnosis and understanding of retinal pathologies and pathogenesis.
Detrending Time Series

Trends in time series may produce spurious covariation among variables. Although it is clearly necessary to model such sources of covariation, it is equally necessary to model those processes correctly. This article considers two types of processes that produce trends in time series. Trend stationary processes produce a constant rate of change in the level of a variable. Difference stationary processes produce a random rate of change in the level of a variable. Methods to detrend time series presuppose one or the other of these two basic processes. Tests to distinguish trend stationary from difference stationary processes are described and illustrated. It is shown that choice of method makes a difference and that the consequences of incorrectly detrending time series may be severe.
Quark helicity distributions from longitudinal spin asymmetries in muon-proton and muon-deuteron scattering

We present a leading order evaluation of the helicity distributions for the three lightest quark and anti-quark flavours, derived from the double-spin asymmetries measured by the COMPASS experiment at CERN. The data, obtained by scattering a 160 GeV muon beam off longitudinally polarised NH3 and 6LiD targets, cover the Bjorken variable x range 0.004 < x < 0.7. The resulting values of the sea quark distributions are all small and do not show any sizable dependence on x in the range of the measurements. No significant difference is observed between the strange and anti-strange helicity distributions, both compatible with zero. The integrated value of the polarised flavour sea asymmetry is slightly positive, about 1.5 standard deviations away from zero.
Piezoelectric properties of ferroelectric PZT-polymer composites

The most widely used material for active transducer applications is the ferroelectric ceramic PZT. Composites made of ferroelectric ceramics combined with polymers have several advantages over pure ceramics. Diphasic composites of PZT (and La/Ca modified PZT) combined with various polymers such as PVDF, PVC, PVA, epoxy resin and co-polymers have been widely studied and reported in the literature. In this paper we present the preparation and study of PZT-PVDF composites of 0-3 connectivity. The composites are prepared by two methods, namely (i) the solvent-cast method and (ii) the hot-press method. The piezoelectric strain coefficient (d33) is studied as a function of volume fraction of PZT in PVDF. The dielectric constant (k) is measured as a function of temperature and the piezoelectric voltage coefficient (g33) of the composite is determined. The experimental values of the dielectric constant, d33 and g33 of the composites are compared with the earlier reported values and the theoretical values proposed by Furukawa et al (Furukawa T, Ishida K and Fukada E 1979 J. Appl. Sci. 50 4904) and Bhimasankaram et al (Bhimasankaram T, Suryanarayana S V and Prasad G P 1998 Curr. Sci. 4 967). The composite with 0.5 PZT volume fraction prepared by the hot-press method is found to possess a reasonably high d33 value and exhibit good flexibility and stability with time.
Non-invasive ultrasound surgery: role of microbubble enhanced cavitation

A method to make in-vivo acoustic cavitation practical as a mechanism for non-invasive ultrasound surgery is presented. Unlike thermal ablation mechanisms, acoustic cavitation can destroy tissue without heating complex overlying layers. However, cavitation thresholds are widely varying in tissues and cavitation requires high intensities to initiate. We have shown that introducing microbubbles (Optison/sup TM/ ultrasound contrast agent) significantly reduces the threshold for cavitation in canine kidneys. Non-invasive ultrasound surgery of deep-seated tissues may be possible using this approach.
GLS-BASED UNIT ROOT TESTS WITH MULTIPLE STRUCTURAL BREAKS UNDER BOTH THE NULL AND THE ALTERNATIVE HYPOTHESES

Perron (1989, Econometrica 57, 1361–1401) introduced unit root tests valid when a break at a known date in the trend function of a time series is present. In particular, they allow a break under both the null and alternative hypotheses and are invariant to the magnitude of the shift in level and/or slope. The subsequent literature devised procedures valid in the case of an unknown break date. However, in doing so most research, in particular the commonly used test of Zivot and Andrews (1992, Journal of Business & Economic Statistics 10, 251–270), assumed that if a break occurs it does so only under the alternative hypothesis of stationarity. This is undesirable for several reasons. Kim and Perron (2009, Journal of Econometrics 148, 1–13) developed a methodology that allows a break at an unknown time under both the null and alternative hypotheses. When a break is present, the limit distribution of the test is the same as in the case of a known break date, allowing increased power while maintaining the correct size. We extend their work in several directions: (1) we allow for an arbitrary number of changes in both the level and slope of the trend function; (2) we adopt the quasi–generalized least squares detrending method advocated by Elliott, Rothenberg, and Stock (1996, Econometrica 64, 813–836) that permits tests that have local asymptotic power functions close to the local asymptotic Gaussian power envelope; (3) we consider a variety of tests, in particular the class of M-tests introduced in Stock (1999, Cointegration, Causality, and Forecasting: A Festschrift for Clive W.J. Granger) and analyzed in Ng and Perron (2001, Econometrica 69, 1519–1554).
Electrospray pulsation: A diagnostic to understand cone-jet stability and minimum flow

Detailed current and flow rate measurements obtained during pulsation mode nano-electrospray of ethylene glycol solutions are presented. High temporal resolution current measurements reveal for the first time that current is observed at the electrode immersed in the electrospray fluid, even when there is no observed spray. This current, believed to be the charging current associated with electrode and meniscus polarization, is dependent upon the voltage applied to the electrospray system. Quantitatively, the total charge transfer that is observed during the non-spray period of the pulsation approximates to that required to obtain electrostatic equilibrium in the conical meniscus, and is relatively independent of the fluid conductivity. A linear relationship exists between this charging current and the observed pulsation frequency. Pulse shape, indicated by the parameters of spray current rise time, fall time, and spray current pulse duration, are observed to be independent of frequency for a given solutio.
SPH Radiative Hydrodynamics Methods

Abstract In this paper, we review the radiative hydrodynamics methods based upon Smoothed Particle Hydrodynamics(SPH). There are already various implementations so far, which can be categorized into three types: moment equation solvers, Monte Carlo methods, and ray-tracing schemes. These codes have been applied to various astrophysical problems including dynamics of dense proto-stellar cores, photoionization feedback of massive stars on molecular clouds, radiative feedback in the early universe, etc. Among these different methods, we focus on the ray-tracing schemes. We also describe one particular ray-tracing code RSPH in some details.
Speckle observations with PISCO in Merate – III. Astrometric measurements of visual binaries in 2005 and scale calibration with a grating mask

We present relative astrometric measurements of visual binaries made during the first semester of 2005, with the Pupil Interferometry Speckle Camera and Coronagraph (PISCO) at the 102-cm Zeiss telescope of the Brera Astronomical Observatory, in Merate. We performed 214 new observations of 192 objects, with angular separations in the range 0.2-4.3arcsec, and with an average accuracy of 0.01arcsec. Most of the position angles could be determined without the usual 180° ambiguity, and their mean error is . Our sample contains orbital couples as well as binaries whose motion is still uncertain. The purpose of this long-term programme is to improve the accuracy of the orbits and constrain the masses of the components. For the first time with PISCO, the astrometric calibration was made with a grating mask mounted at the entrance of the telescope. The advantage of this procedure is to provide a reliable and fully independent scale determination. We have found two possible new triple systems: ADS 7871 and KUI 15. We propose a preliminary orbit for ADS 4208.
Ageing of electrochromic WO3 coatings characterized by electrochemical impedance spectroscopy

We have developed a method for characterization of ageing of electrochromic materials by electrochemical impedance spectroscopy (EIS). Electrochromic WO3 thin films have been electrochemically cycled in propionic acid electrolyte and probed by EIS and optical measurements. A very small amount of optical degradation was observed in both the bleached and coloured states. The samples exhibited a few hundred times higher impedance in the bleached state than in the coloured state. It was observed that, in the bleached state, impedance values at low frequencies increased significantly with increasing number of cycles.
Linear Response of Laminar Premixed Flames to Flow Oscillations: Unsteady Stretch Effects

�c and � � s ,forcurvatureand hydrodynamic strain, respectively. Unsteady curvature effects on the flame surface area become significant when j� � c jSt 2 2 � O� 1� and are responsible for the experimentally observed reduction in the flame front wrinkle size in the flow direction [referred to as “filtering” by Bourehla and Baillot (Bourehla, A. , and Baillot, F. , “Appearance and Stability of a Laminar Conical Premixed Flame Subjected to an Acoustic Perturbation,” Combustion and Flame,
Two Modified Hybrid Conjugate Gradient Methods Based on a Hybrid Secant Equation

Abstract Taking advantage of the attractive features of Hestenes–Stiefel and Dai–Yuan conjugate gradient methods, we suggest two globally convergent hybridizations of these methods following Andrei's approach of hybridizing the conjugate gradient parameters convexly and Powell's approach of nonnegative restriction of the conjugate gradient parameters. In our methods, the hybridization parameter is obtained based on a recently proposed hybrid secant equation. Numerical results demonstrating the efficiency of the proposed methods are reported.
The (not so) peculiar case of the Padua family

The Agnia asteroid family was recently studied by Vokrouhlicky et al. because of its peculiar and, so far, unique relationship with the z 1 secular resonance. The Agnia family is almost entirely contained within the high-order secular resonance z 1 . Here, I study another family in the middle belt that is characterized by its interaction with the z 1 resonance, the Padua family. More than 75 per cent of its members are currently on z 1 librating orbits, and therefore several of the techniques used by Vokrouhlicky et al. can also be applied to this family. As for the case of the Agnia family, numerical integration methods and Monte Carlo models can be used to set lower and upper limits on the family age, and to obtain estimates on the fraction of prograde rotators. The constraints obtained on the family age and original ejection velocity field may be used to set limits on the dynamical mobility caused by low-energy collisions, that is dependent on the yet poorly known exponent a that best fits the size distribution of objects of less than 5 km in diameter. In this work, the Padua dynamical family was obtained in both the proper element and frequency domains. Numerical simulations of family members in the space of the z 1 resonance variable (σ, dσ/dt) suggest that the family is at least 25 Myr old. The conservation of the z 1 K' 2 conserved quantity implies that the original ejection velocity field was of V EJ = 35.0 ± 8.5 m s -1 . Monte Carlo models of the diffusion of the semimajor axis caused by the Yarkovsky and Yarkovsky-O'Keefe-Radzievsky-Paddack (YORP) effects also confirm the results obtained with the alternative approaches. The Padua family is 24 +28 -20 Myr old, and it was probably created by an impact that ejected fragments with average ejection velocities of V EJ = 30.0 +2.0 -4.0 m s -1 . The fact that the Padua family is at least 25 Myr old suggests that low-energy collisions as modelled by Dell'Oro & Cellino should have played a minor role in the semimajor axis diffusion of the family members. My results are at best consistent with a value of a equal to -2.3. Families interacting with secular resonances such as the Agnia and Padua families can provide useful information not only about their age and original ejection velocity field, but also on the yet poorly known cumulative size distribution of objects of diameters of 5 km and less.
A deformed medium including a defect field and differential forms

We consider basic equations for a deformed medium including a defect field on the basis of differential forms. To make our analysis, we extend three basic equations: (I) an incompatibility equation; (II) the Peach-Köhler equation; (III) the Navier equation based on the Hodge duality of the deformed medium. By combining two exterior differential operators, we derive (I) an incompatibility equation that extends the compatibility equation to include a defect field. The Hodge dual of the incompatibility equation becomes a generalized stress function, which includes previously derived stress functions such as Beltrami's, Morera's, Maxwell's and Airy's stress functions. By applying homotopy operators, we extend (II) the Peach-Köhler equation to include disclinations. In this case, we can define the basic quantities of stress space by analogy with the monopole theory. By combining exterior differential operators and star operators, we extend (III) the Navier equation to include a defect field. In this analysis, we define a Navier operator that is related to the Laplace operator through Hodge duality. We consider gauge conditions for a defect field based on the differential geometry of a deformed medium. This suggests a duality between yielding and fatigue fractures. The gauge condition in strain space-time is interpreted as basic relations in polycrystalline plastic deformation.
Testing for Unit Roots in Models with Structural Change

This paper considers the unit root tests in models with structural change. Particular attention is given to their dependency on the limiting ratios of the subsample sizes between breaks. The dependency is analyzed in detail, and the invariant testing procedure based on a transformed model is developed. The required transformation is essentially identical to the generalized least-squares correction for heteroskedasticity. The limiting distributions of the new tests do not depend on the relative sizes of the subsamples and are shown to be simple mixtures of the limiting distributions of the corresponding tests from the independent unit root models without structural change.
Observing and modeling nonlinear dynamics in an internal combustion engine

We propose a low-dimensional, physically motivated, nonlinear map as a model for cyclic combustion variation in spark-ignited internal combustion engines. A key feature is the interaction between stochastic, small-scale fluctuations in engine parameters and nonlinear deterministic coupling between successive engine cycles. Residual cylinder gas from each cycle alters the in-cylinder fuel-air ratio and thus the combustion efficiency in succeeding cycles. The model’s simplicity allows rapid simulation of thousands of engine cycles, permitting statistical studies of cyclic-variation patterns and providing physical insight into this technologically important phenomenon. Using symbol statistics to characterize the noisy dynamics, we find good quantitative matches between our model and experimental time-series measurements. @S1063-651X~98! 08903-X#
Lag Order and Critical Values of the Augmented Dickey-Fuller Test

Response surface analysis is used to obtain approximate finite-sample critical values for the augmented Dickey–Fuller (ADF) test. Previous studies estimating the critical values for the test have generally ignored their possible dependence on the lag order. This study shows that the lag order, in addition to the sample size, can affect the finite-sample behavior of the test. The result points to the importance of correcting for the effect of lag order in applying the ADF test.
Particle–wave association on a fluid interface

A small liquid drop can be kept bouncing on the surface of a bath of the same fluid for an unlimited time when this substrate oscillates vertically. With fluids of low viscosity the repeated collisions generate a surface wave at the bouncing frequency. The various dynamical regimes of the association of the drop with its wave are investigated first. The drop, usually a simple ‘bouncer’, undergoes a drift bifurcation when the forcing amplitude is increased. It thus becomes a ‘walker’ propagating at a constant velocity on the interface. This transition occurs just below the Faraday instability threshold, when the drop becomes a local emitter of a parametrically forced wave. A model of the particle–wave interaction accounts for this drift bifurcation. The self-organization of several identical bouncers is also investigated. At low forcing, bouncers form bound states or crystal-like aggregates. At larger forcing, the collisions between walkers reveal that their interaction can be either repulsive or attractive, depending on their distance apart. The attraction leads to the spontaneous formation of orbiting pairs, the possible orbit diameters forming a discrete set. A theoretical model of the non-local interaction resulting from the interference of the waves is given. The nature of the interaction is thus clarified and the various types of self-organization recovered.
Storm surges on a continental shelf

This paper gives a theoretical analysis of storm surges generated on a continental shelf by moving wind fields; surges generated in the ocean and propagated on to the shelf are also investigated. A continental shelf of uniform depth and width, bounded by a long straight coast and connected with an infinitely deep ocean, is considered. In studying the motion of the shelf sea, bottom friction and Coriolis force are taken into account, and it is supposed that conditions are the same in all vertical sections normal to the coast. The theory is applied to the problem of storm surges on the west coast of the British Isles. It is shown that these surges are generated by wind fields, associated with moving depressions, acting over the sea of the continental shelf to the south of Ireland. In two cases the observed surge at Milford Haven has been reproduced satisfactorily by the theory.
Edge waves on a sloping beach

The set of eigenfrequencies of a mechanical system forms its spectrum. A discussion is given of systems with discrete, continuous and mixed spectra. It is shown that resonance occurs at discrete points of the spectrum, and at cut-off frequencies (end-points of the continuous spectrum). The motion in a semi-infinite canal of finite width closed by a sloping beach has a mixed spectrum. The inviscid theory predicts that at a discrete frequency the resonance is confined to the neighbourhood of the beach (inviscid edge wave), while at a cutoff frequency the resonance extends a long way down the canal. The latter resonance is confined to the neighbourhood of the beach (viscous edge wave) by viscosity which is important near a cut-off frequency. Especially large resonances are predicted for a series of critical angles, of which the largest is 30°. The theory is verified experimentally in the frequency range 100 to 17c/min for the angles 37⋅6 and 29⋅5°.
Normalizing heat treatment effect on low alloy steel weld metals

In equipment manufacturing, there are occasions that the base metal (BM) need to be hot or cold worked prior to welding. After welding, the components have to be submitted to a normalizing heat treatment in order to recover its original mechanical properties. In this work four different low alloy steel weld metals (WM) both in the as welded condition and after normalizing heat treatment have been studied. Optical and scanning electron microscopy were used to observe the WM microstructure. Tensile and Charpy V toughness testing and microhardness measurements were used to evaluate the WM mechanical properties. Results show that normalizing breaks the original columnar structure in the as welded condition to an equiaxial structure similar to the one of the BM. Due to low carbon content of the WM it was observed a high decrease on the tensile properties specially the yield strength after normalizing. In respect of toughness, the normalizing heat treatment was observed to increase the Charpy V energy, except for one WM where a great content of martensite-austenite-bainite constituent was formed. Opposite to others post weld heat treatments, normalizing modifies significantly the microstructure and the resulting mechanical properties of the WM. Although normalizing is always beneficial to the BM, care must be taken in order to select welding consumables.