Miracle-dz/UniFAR-FTUs huggingface dataset:
Experimental Evidence in Acoustics of the Violation of Time-Reversal Invariance Induced by Vorticity

Self-focusing on a point source using an acoustic time-reversal mirror (TRM) permits to test the invariance under time-reversal in fluids. The presence of vorticity in the fluid breaks time-reversal invariance as can be shown with a TRM by measuring the deflection of a time-reversed focused acoustic wave propagating through a uniform distribution of vorticity. Experimental as well as theoretical aspects are presented.
Oxygen incorporation effects in annealed epitaxial La(1−x)SrxMnO3 thin films

This paper presents our results regarding oxygen incorporation effects in epitaxial La(1-x)SrxMnO3 thin films, deposited on SrTiO3 (001) single crystal substrates, by annealing in different gas mixtures of argon and oxygen. A particular emphasis is placed on the correlation of structural properties with the magnetic properties of the films, Curie temperature, and coercive field. In this sense, we demonstrate that the evolution of the diffuse part of the ω-scans performed on the films are due to oxygen excess in the film lattice, which creates cationic vacancies within the films. Also, we show that two regimes of oxygen incorporation in the films exist, one in which the films evolve toward a single phase and oxygen stoichiometry is recovered, and a second one dominated by oxygen over-doping effects. In order to support our study, XPS measurements were performed, from which we have evaluated the Mn3+/Mn4+ ionic ratio.
A system of mesopic photometry

This paper describes a system of photometry designed to make no unjustifiable assumptions, and to have a strong visual linkage. It spans the photopic, mesopic, and scotopic regions and is based on brightness matching a 10-degree field, centrally fixated. An intensive investigation was made on the trichromator at the National Physical Laboratory, Great Britain, and an extensive one, using a greater number of observers, on the trichromator at the National Research Council, Canada. A bipartite field allowed equal brightness settings of the aperture colour by each of nine observers. The stimuli tested were both spectral and nonspectral and the data were used to derive formulae which a user could employ. From inserting conventional photometric quantities of a stimulus, which might for example be a light source, the user can obtain its corresponding photometric value whether it be photopic, mesopic, or scotopic.
Precise determination of universal finite volume observables in the Gross-Neveu model

The Gross-Neveu model is a quantum field theory in two space time dimensions that shares many features with quantum chromo dynamics. In this thesis the continuum model and its discretized versions are reviewed and a finite volume renormalization scheme is introduced and tested. Calculations in the limit of infinitely many fermion flavors as well as perturbative computations are carried out. In extensive Monte-Carlo simulations of the one flavor and the four flavor lattice models with Wilson fermions a set of universal finite volume observables is calculated to a high precision. In the one flavor model which is equivalent to the massless Thirring model the continuum extrapolated Monte-Carlo results are confronted with an exact solution of the model.
The Role of Experience in Numerical Skill: Multiplication Performance in Adults from Canada and China.

Adults educated either in the People s Republic of China or in Canada solved single-digit multiplication problems. Chinese adults were faster and made fewer errors than Canadian adults and showed smaller increases in latency and errors as problem size increased. Chinese adults transformed problems with the larger operand on the left e.g. 9 6 by reversing the digits and solving the complementary problem e.g. 6 9. Only the Canadian adults showed a substantial advantage in latencies and errors for problems with operands of 5. Although both groups showed a latency advantage on ties e.g. 3 3 as compared to other problems, the advantage was much larger for the Canadian than for the Chinese adults. These findings were only partially attributable to overall differences in skill; patterns of differences persisted when groups were equated on multi-digit arithmetic performance. Chinese adults made more errors that reflect verbal-production processes that may occur after retrieval, whereas Canadian adults made more e.
Existence and Stability for Mathematical Models of Sedimentation–Consolidation Processes in Several Space Dimensions☆

Abstract In this paper, we study several spatially multidimensional initial-boundary value problems modelling sedimentation–consolidation processes of a flocculated suspension. This solid–fluid mixture is considered as two superimposed continuous media differing in density and viscosity. The phenomenological foundation and derivation of the mathematical model are based on the previous work by R. Burger et al. (2000, Z. Angew. Math. Mech . 80 , 79–92). We study the full coupling of the conservation of mass equation and the conservation of linear momentum equation. For different types of regularization, we establish energy estimates. The dissipative nature of the whole system assures the existence as well as the stability (long time asymptotics) of a solution of the system (provided that the viscosities of the fluid are large enough). Moreover, the energy estimates might serve as the foundation for the design of numerical algorithms to simulate the system.
Dynamics of all the Raman-active coherent phonons in Sb2Te3 revealed via transient reflectivity

The phonon dynamics in Sb2Te3 is investigated using femtosecond time-resolved reflection measurements. Time evolution of the reflectivity shows the dynamics of all of the Raman-active optical phonons of Sb2Te3 (A1g1, A1g2, Eg1, and Eg2). The amplitude of these coherent phonons strongly depends on the polarization of the excitation pulse, which can be explained by the analysis based on the Raman tensors. Fine tuning of the polarization enables the observation of even Eg1 phonons with small amplitude ( ΔR/R≈ 10−7) and short decay time (<1 ps).
Adsorption of small hydrocarbon molecules on Si surfaces: Ethylene on Si(001)

The interaction between small unsaturated hydrocarbon molecules of C(2)H(4) with a vicinal silicon (001) surface is studied by means of reflectance anisotropy spectroscopy and analyzed with first principles calculations. Our results confirm that ethylene adsorbs without breaking the silicon dimers. Comparison of theoretical optical spectra with experimental data shows that the C(2)H(4) molecules lay on top of the silicon dimers from low to high coverage. This occurs even though, from a purely energetic point of view, a bridge configuration would be favorable at 1 monolayer coverage.
Human Energy Budget Modeling in Urban Parks in Toronto and Applications to Emergency Heat Stress Preparedness

AbstractThe current study tests applications of the Comfort Formula (COMFA) energy budget model by assessing the moderating effects of urban parks in contrast to streets, and it also looks at the influence of park types (“open” or “treed”). Exploration into energy budget modeling is based on empirical meteorological data collected in Toronto, Ontario, Canada, on fair-weather days plus the effects of a heat wave and climate change, at various metabolic activity levels. Park cooling temperature intensities ranged from 3.9° to 6.0°C, yet human energy budgets were more closely correlated to incoming solar radiation than to air temperature. A strong linear dependence was found, with absorbed radiation (correlation coefficient squared r2 = 0.858) explaining the largest fraction of energy budget output. Hence, although the four parks that were examined are classified as urban green space, the distinctive treed areas showed a greater budget decrease than did open park areas (−25.5 W m−2). The greatest difference .
On the upper bounding approach to thermal convection at moderate rayleigh numbers

Abstract Two upper bounding problems for thermal convection in a layer of fluid contained between perfectly conducting stress-free boundaries are treated numerically. Since the Euler equations resulting from this variational approach are simpler than the Navier-Stokes equations, they allow numerical calculations to be carried out economically to fairly large values of the Rayleigh number. The upper bounding problem formulated by Howard (1963), which yields a Nusselt number independent of Prandtl number, diverges from the correct behavior as the Rayleigh number increases. In hopes of coming closer to results of previous investigations of the Boussinesq equations of motion, a more restrictive upper bounding problem is formulated. For large Prandtl numbers the momentum equation is linearized and is used as an explicit side constraint on the variational problem, thereby forcing the solutions to more closely resemble the solutions of the Boussinesq equations. Numerical calculations at values of the Rayleigh nu.
European Extremely Large Telescope Site Characterization I: Overview

The site for the future European Extremely Large Telescope (E-ELT) is already known to be Armazones, near Paranal (Chile). The selection was based on a variety of considerations, with an important one being the quality of the atmosphere for the astronomy planned for the ELT. We present an overview of the characterization of the atmospheric parameters of candidate sites, making use of standard procedures and instruments as carried out within the Framework Programme VI (FP6) of the European Union. We have achieved full characterization of the selected sites for the parameters considered. Further details on adaptive optics results and climatology will be the subject of two forthcoming articles. A summary of the results of the FP6 site-testing campaigns at the different sites is provided.
Numerical Simulation of the Jet Impingement Cooling of a Circular Cylinder

A numerical investigation was carried out on circular jet impingement heat transfer from a constant temperature circular cylinder to understand the major parameters which influence the fluid flow and heat transfer characteristics. In this study, air was considered as the working fluid. The flow was considered to be three-dimensional, incompressible, and turbulent. To select a suitable turbulence model for the parametric study, numerical simulations were carried out with standard k-ϵ, standard k-ω, RNG k-ϵ, Realizable k-ϵ, and SST k-ω turbulence models for modeling Reynolds stress terms. Simulations were also carried out using four low Reynolds number models. The results obtained using these models were compared with the available experimental results of jet impingement heat transfer from circular cylinder. It was identified that the RNG k-ϵ model predicts heat transfer characteristics better compared to all other turbulence models considered in this study. Using this turbulence model, a parametric study was carried out for the Reynolds number (Re d ), defined based on the diameter of the nozzle ranging from 10,000 to 50,000. The ratio of distance between the nozzle exit and the cylinder surface to the diameter of the jet (h/d) was varied from 4 to 16 and the ratio of nozzle diameter to cylinder diameter (d/D) varied from 0.11 to 0.25. For a fixed Re d and d/D, the stagnation point Nusselt number increases as h/d decreases. The stagnation point Nusselt number decreases as d/D increases for a fixed value of Re d and h/d. The effects of change in h/d and d/D are significant only near the stagnation region.
A statistical survey of local planetary nebulae

An empirically determined relation between the ionized masses of planetary nebulae and a particular function of observational quantities is used to derive distances to 299 primarily nearby planetary nebulae. These distances are used to investigate the scale height of the galactic distribution of planetaries (125 pc), the rate of formation of planetaries (5=±2X 10 -3 PN kpc -3 yr _1 ), and certain aspects of the evolution of the nebulae.
Friction modeling, identification and compensation

High-precision tracking requires excellent control of slow motion and positioning. Recent advances have provided dynamic friction models that represent almost all experimentally observed properties of friction. The state space formulation of these new mathematical descriptions has the property that the state derivatives are continuous functions. This enables the application of established theories for nonlinear systems. The existence of locally stable fixed points does not imply for nonlinear systems the absence of limit cycles (periodic orbits) or unstable solutions. Therefore, global properties of PI velocity and PID position control are analyzed using a passivity and Lyapunov based approach. These linear control laws are then extended by nonlinear components based on the friction model considered. The applications presented in this work are in the domains of mechatronics and machine-tools.
State-Dependent Riccati-Equation-Based Guidance Law for Impact-Angle-Constrained Trajectories

IN MANY advanced guidance applications, it is required to intercept the target from a particular direction: that is, to achieve a certain impact angle [1–3]. Closed-form solutions for energyoptimal impact-angle-constrained guidance laws have been proposed for a stationary target by Ryoo et al. [4], who used the linear quadratic regulator technique after linearizing the engagement kinematics. The guidance law proposed by them captures all impact angles from any initial launch angle in a planar engagement scenario. Lu et al. [5] solved the problem of guiding a hypersonic gliding vehicle in its terminal phase to a stationary target using adaptive proportional navigation guidance. Ohlmeyer and Phillips [6] extended the idea of explicit guidance (proposed by Cherry [7]) to include a terminal impact angle constraint. However, the simulations by Ohlmeyer and Phillips [6] are carried out only for a vertical impact against a stationary target, and the impact angle errors encountered are sensitive to the launch altitude.
Solar cycle dependence of ion cyclotron wave frequencies

Electromagnetic ion cyclotron (EMIC) waves have been studied for decades, though remain a fundamentally important topic in heliospheric physics. The connection of EMIC waves to the scattering of energetic particles from Earth's radiation belts is one of many topics that motivate the need for a deeper understanding of characteristics and occurrence distributions of the waves. In this study, we show that EMIC wave frequencies, as observed at Halley Station in Antarctica from 2008 through 2012, increase by approximately 60% from a minimum in 2009 to the end of 2012. Assuming that these waves are excited in the vicinity of the plasmapause, the change in Kp in going from solar minimum to near solar maximum would drive increased plasmapause erosion, potentially shifting the generation region of the EMIC to lower L and resulting in the higher frequencies. A numerical estimate of the change in plasmapause location, however, implies that it is not enough to account for the shift in EMIC frequencies that are observed at Halley Station. Another possible explanation for the frequency shift, however, is that the relative density of heavier ions in the magnetosphere (that would be associated with increased solar activity) could account for the change in frequencies. In terms of effects on radiation belt dynamics, the shift to higher frequencies tends to mean that these waves will interact with less energetic electrons, although the details involved in this process are complex and depend on the specific plasma and gyrofrequencies of all populations, including electrons. In addition, the change in location of the generation region to lower L shells means that the waves will have access to higher number fluxes of resonant electrons. Finally, we show that a sunlit ionosphere can inhibit ground observations of EMIC waves with frequencies higher than ∼0.5 Hz and note that the effect likely has resulted in an underestimate of the solar‐cycle‐driven frequency changes described here.
GABAA and GABAB Receptors Mediate GABA-Induced Intracellular Ca2+ Signals in Human Brain Microvascular Endothelial Cells

Numerous studies recently showed that the inhibitory neurotransmitter, γ-aminobutyric acid (GABA), can stimulate cerebral angiogenesis and promote neurovascular coupling by activating the ionotropic GABAA receptors on cerebrovascular endothelial cells, whereas the endothelial role of the metabotropic GABAB receptors is still unknown. Preliminary evidence showed that GABAA receptor stimulation can induce an increase in endothelial Ca2+ levels, but the underlying signaling pathway remains to be fully unraveled. In the present investigation, we found that GABA evoked a biphasic elevation in [Ca2+]i that was initiated by inositol-1,4,5-trisphosphate- and nicotinic acid adenine dinucleotide phosphate-dependent Ca2+ release from neutral and acidic Ca2+ stores, respectively, and sustained by store-operated Ca2+ entry. GABAA and GABAB receptors were both required to trigger the endothelial Ca2+ response. Unexpectedly, we found that the GABAA receptors signal in a flux-independent manner via the metabotropic GABAB receptors. Likewise, the full Ca2+ response to GABAB receptors requires functional GABAA receptors. This study, therefore, sheds novel light on the molecular mechanisms by which GABA controls endothelial signaling at the neurovascular unit.
Backscattering By a Bruderhedral Reflector: a Physical Optics Based Approach

A Physical Optics model is developed in this work to analyze the backscattering properties of a perfectly conducting Bruderhedral diplane reflector. Such a reflector is obtained by replacing one face of a conventional right angled dihedral corner reflector with a section of a cylinder. It has a relatively large radar cross section and exhibits a much wider lobe in the plane parallel to the seam with respect to a conventional dihedral corner. The here proposed approach employs the Geometrical Optics to take into account the electromagnetic interactions between the faces and furnishes the backscattered field by evaluating the radiation integral involving the induced surface currents in the Physical Optics approximation.
An approach to computing bounds on H/sub /spl infin// performance under hard constraints

A number of standard control problems can be formulated as optimization problems where the goal is to minimize the H/sub /spl infin//-norm of some transfer function while subject to constraints on, for example, system bandwidth or peak sensitivity or output variance. Such constraints usually limit the achievable H/sub /spl infin// performance, but, since the constraints are typically included in the H/sub /spl infin// optimization problem only indirectly through the selection of weights, it is generally not known to what degree the constraints limit the performance. This paper shows how lower bounds on the achievable H/sub /spl infin// norm can be computed for problems where the objective function and constraints can all be written in terms of the sensitivity function. Both pointwise-in-frequency constraints (such as the requirement that the peak sensitivity be limited) and integral constraints (such as the requirement that the output variance be limited when subject to a stochastic disturbance) are dealt with. All constraints are explicitly included in the problem formulation; the solution approach involves optimal curve shaping and is, at least for the single-input single-output case, computationally straightforward.
Delay‐dependent passivity and passification for uncertain Markovian jump systems with time‐varying delays

This paper deals with the problems of passivity analysis and passivity‐based controller design for Markovian jump systems with both time‐varying delays and norm‐bounded parametric uncertainties. Firstly, new delay‐dependent conditions for the considered system to be passive are obtained by using a mode‐dependent Lyapunov functional and by introducing some slack variables. These conditions are expressed by means of LMIs that are easy to check. It is shown through a numerical example that the obtained passivity conditions are less conservative than the existing ones in the literature. Secondly, the passification problem is investigated. On the basis of the obtained passivity conditions, dynamic output‐feedback controllers are designed, which ensure that the resulting closed‐loop system is passive. The effectiveness of the proposed design method is demonstrated by a numerical example. Copyright © 2011 John Wiley & Sons, Ltd.
Some observations on the thermal behavior of the mesosphere

Abstract Temperature and wind soundings of the stratosphere and mesosphere using the acoustic grenade technique were made over Barrow, Alaska (71N), during the arctic winter night and during the summer. The winter mesosphere temperatures were generally warmer than at any other location and season and were variable from day to day. Temperatures oscillated with height in wavelike fashion at magnitudes up to 30–40C between 70 and 90 km. These wavelike structures were found to exist also in the winter mesosphere at Churchill (59N) and Wallops Island (38N). However, the magnitude of the oscillations decreased with latitude to a value of 20–25C at Wallops. Conversely, variability In summer armed to decrease with increasing latitude and the wavelike structure was suppressed entirely at Barrow. Temperature variations in summer at Barrow were less than 10C from sounding to sounding at any given altitude from 40 to 85 km. Extremely low mesopause temperatures ranging from 130–140K near 85 km were observed in all of .
Counterions at disordered charged planar surfaces

Using field-theoretic and numerical methods, we study counterion density profiles at planar surfaces with disordered surface-charge distributions. Experimental examples include mixed lipid bilayers and weakly charged surfaces where pH-controlled charge regulation takes place. Quenched as well as annealed disordered surface charge distributions exhibit markedly enhanced counterion densities close to the surface even for weak coupling parameter, in contrast to ordered dilute substrates where the counterion surface enhancement is relatively weak.
On the segmentation of vascular geometries from medical images

A comprehensive analysis of vascular morphology and the application of generic models of vascular biomechanics to specific patients require the ability of extracting a geometrical representation of the vascular anatomy from medical images. Owing to the wide range of clinical manifestations of vascular disease and associated imaging modalities and protocols, several segmentation methods have been proposed over the last 20 years and are available in the literature. In this paper, we review the methods of segmentation of angiographic medical images and identify major advantages and disadvantages of state‐of‐the‐art techniques. We further discuss the performance of some of the most popular intensity‐based and gradient‐based methods using a set of images of peripheral by‐pass grafts acquired with magnetic resonance angiography (MRA). We then propose a threshold front method for the segmentation of MRA images and assess its performance using two anatomic scale replica models, reproducing a normal and a stenotic peripheral artery. The threshold front algorithm is a simple, fast and parameter‐free (still adaptive) method achieving segmentation errors below pixel resolution. Copyright © 2009 John Wiley & Sons, Ltd.