Miracle-dz/UniFAR-FTUs huggingface dataset:
High fluence ultrafast dynamics of semiconductor saturable absorber mirrors

The ultrafast nonlinear dynamics of InGaAs/InP semiconductor saturable absorber mirrors are investigated using reflective pump–probe measurements. At high fluence, ultrafast induced absorption begins to dominate over absorption bleaching. Above the InGaAs quantum well band gap, the differential reflectivity shows a ∼1 ps transient due to nonequilibrium carrier dynamics. Below band gap, the signal is dominated by a strong two-photon absorption component followed by induced absorption that decays with a time constant of ∼5 ps; these components are attributed to nonlinear absorption and subsequent carrier diffusion in the InP layer.
Hermitian functionals on -algebras and duality characterizations of *-algebras

The hermitian functionals on a unital complex Banach algebra are defined here to be those in the real span of the normalized states (tangent functionals to the unit ball at the identity). It is shown that every functional f in the dual A' of A can be decomposed asf= h + ik, where h and k are hermitian functionals. Moreover, this decomposition is unique for every f E A' iff A admits an involution making it a C*-algebra, and then the hermitian functionals reduce to the usual real or symmetric functionals. A second characterization of C*-algebras is given in terms of the separation properties of the hermitian elements of A (real numerical range) as functionals on A'. The possibility of analogous theorems for vector states and matrix element functionals on operator algebras is discussed, and potential applications to the representation theory of locally compact groups are illustrated. Introduction. As the abstract indicates, we introduce here the notion of a hermitian functional on an arbitrary complex Banach algebra (B-algebra) with norm-one unit; these functionals generalize real measures on a compact Hausdorff space (qua functionals on C(X)) and the real or symmetric functionals on a unital C*-algebra. Our definition exploits the earlier involution-independent geometrical characterization of the positive functionals or states on a C*-algebra, due to Bohnenblust and Karlin [2], as well as Lumer's strikingly successful use of this to define states on general B-algebras and hermitian members of such algebras [7]. We show rather easily here that the dual space A' of A is the complex span of the states (a mild improvement of the Bohnenblust-Karlin vertex theorem [2]) and thus that every f E A' can be expressed as f= h + ik for suitable " real "and "imaginary" hermitian parts h and k. The entire dual space of A is thus brought into play in the geometrical study of A, making possible two considerably deeper duality characterizations of C*-algebras: A admits a C* involution iff A' decomposes as a real direct sum A' = H(A') + iH(A') of hermitians, or equivalently iff the hermitians in A (or their complex span) separate points in A'. (This brings the study Received by the editors March 20, 1970 and, in revised form, December 15, 1970. AMS 1969 subject classifications. Primary 4650, 4660; Secondary 4665, 2260.
Gemini primary mirror in situ wash

The Gemini twins were the first large modern telescopes to receive protected silver coatings on their mirrors in 2004. The low emissivity requirement is fundamental for the IR optimization. In the mid-IR a factor of two reduction in telescope emissivity is equivalent to increasing the collecting area by the same factor. Our emissivity maintenance requirement is very stringent: 0.5% maximum degradation during operations, at any single wavelength beyond 2.2 μm. We developed a very rigorous standard to wash the primary mirrors in the telescope without science down time. The in-situ washes are made regularly, and the reflectivity and emissivity gains are significant. The coating lifetime has been extended far more than our original expectations. In this report we describe the in-situ process and hardware, explain our maintenance plan, and show results of the coating performance over time.
Computational study on the behaviors of granular materials under mechanical cycling

Considering that fusion pebble beds are probably subjected to the cyclic compression excitation in their future applications, we presented a computational study to report the effect of mechanical cycling on the behaviors of granular matter. The correctness of our numerical experiments was confirmed by a comparison with the effective medium theory. Under the cyclic loads, the fast granular compaction was observed to evolve in a stretched exponential law. Besides, the increasing stiffening in packing structure, especially the decreasing moduli pressure dependence due to granular consolidation, was also observed. For the force chains inside the pebble beds, both the internal force distribution and the spatial distribution of force chains would become increasingly uniform as the external force perturbation proceeded and therefore produced the stress relief on grains. In this case, the originally proposed 3-parameter Mueth function was found to fail to describe the internal force distribution. Thereby, its improved functional form with 4 parameters was proposed here and proved to better fit the data. These findings will provide more detailed information on the pebble beds for the relevant fusion design and analysis.
Travelling waves in heterogeneous media

In this thesis we study the existence of travelling wave type solutions for a reaction diffusion equation in R2 with a nonlinearity which depends periodically on the spatial variable. Specifically we will consider a particular class of nonlinearities where we treat the coefficient of the linear term as a parameter. For this class of nonlinearities we formulate the problem as a spatial dynamical system and use a centre manifold reduction to find conditions on the parameter and nonlinearity for the existence of travelling wave type solutions with particular wave speeds. We then consider what happens if the parameter and the wave speed vary close to zero; by analysing the bifurcations in this case we are able to find travelling wave solutions with periodic and homoclinic structures. Finally we examine what happens to the travelling wave solutions as the period of the periodic dependence in the nonlinearity tends to zero.
Averaged rough surface backscattering vs. bispectral characteristics of surface shape

For an ensemble of wavy surfaces simulating the sea surface, the relation between the averaged resonant backscattering and bispectral surface shape characteristics is studied by means of computer simulation. It is found that for some bispectral characteristics describing waveform peakedness, skewness, ripple concentration, there is a significant correlation to the averaged amplitude of the backscattered signal, the surface spectrum being the same over the ensemble. As an application, a new sea-way model involving, besides to spectral, these bispectral parameters is proposed. This model can describe the manifestation of nonlinear sea-way effects (such as wind-wave interaction, slicks, etc.) in radar images of the sea surface, whereas traditional random phase model (RPM) uses only spectral parameters and thus cannot describe these effects.
Visible and VUV fluorescence from synchrotron radiation induced photoionization and photodissociation of molecular oxygen

Photon induced fluorescence from O2 has been studied in various emission regions 1150-6500 A in the excitation range 14-28eV using the Swedish synchrotron facility MAX in Lund. A rich line structure is observed which is interpreted in terms of autoionization and dissociation of Rydberg levels converging to the a, b, c, and B states in O2+. New features have been observed, for instance, concerning the (c 4Σu−) 3sσg Fano resonance which has been viewed in detail in different detection channels including O2+ and O+ ions.
Spatially Distributed Orthogonal Piezoelectric Shell Actuators: Theory And Applications

Abstract The distributed structural control of elastic shell continua using spatially distributed orthogonal piezoelectric actuators is proposed and three generic distributed feedback algorithms with spatial feedback functions are formulated. In order to prevent spillovers from the modal couplings of feedback forces, the distributed actuators are spatially shaped to be orthogonal to those undesirable modes. Consequently, the distributed feedback functions evolve to modal feedback functions which can be represented as a gain factor and a spatially distributed mode shape (actuator) function. In practice, the actuator can be shaped and convolved based on the prescribed mode shape function and the gain factor can be treated as a weighting factor. To demonstrate the utilities of the generic theory, distributed orthogonal convolving modal actuators designed for a circular ring shell are proposed and their control effectiveness evaluated. Analyses suggested that the primary control action comes from the in-plane membrane control forces; the contribution from the electric bending moment is relatively insignificant for lower natural modes, i.e., n
Spontaneous synchronization driven by energy transport in interconnected networks

Understanding dynamical processes on networks is an important area of research in complex systems, with far reaching implications and applications in many real-world cases. Here we introduce and study a model of intertwined dynamics on interconnected networks, inspired by the human brain, which consists of bidirectionally coupled synchronization and energy transport processes. Remarkably, the proposed model allows the emergence of spontaneous switch-like synchronization transitions driven by the energy transport dynamics, which qualitatively mirror the transitions observed in human brain dynamics between resting-state and cognitive activity. We provide a steady-state analytical explanation for the observed behavior and show that the switch-like transition is robust over a wide range of model parameters and network topologies. Finally, we suggest that the complexity inherent in other interconnected dynamical processes might be responsible for various other emergent behaviors observed in natural systems.
The almost-rigid rotation of viscous fluid between concentric spheres

Two concentric spheres are supposed to rotate about the same axis with almost the same angular velocity, so that the viscous stresses over the surfaces of the spheres induce a flow which may be represented by a small perturbation superimposed upon a rigid body rotation of the fluid as a whole. The governing equations are therefore linearized in the magnitude of the perturbation, and it appears that the validity of this linearization is independent of the Reynolds number of the primary rotation. Attention is then restricted to the case in which the Reynolds number is large, the principal object of the note being to exemplify some of the properties of rotating systems at large Reynolds numbers in terms of a particularly simple mathematical model. It is found that the cylindrical surface that touches the inner sphere (the axis being the axis of rotation) is a singular surface in which velocity gradients are very large. Everywhere outside this cylinder, the fluid rotates as a rigid body with the same angular velocity as the outer sphere. Inside the cylinder, the velocity distribution in the central (inviscid) core of the motion is shown to be determined by the velocity distribution in the boundary layers over the spheres, and explicit solutions are obtained for all these velocity distributions. The mechanics of the cylindrical shear layer itself is also discussed, though no explicit solution is obtained in this case.
Positive temperature coefficient effect in multiwalled carbon nanotube/high-density polyethylene composites

Muldwalled carbon nanotube (MWNT)-filled high-density polyethylene (HDPE) composites were prepared by a solution-precipitation process, and the temperature dependence of electrical conductivity of the MWNT/HDPE composites was studied. An obvious positive temperature coefficient (PTC) effect was found in the MWNT/HDPE composites with a relatively low MWNT concentration. Compared with that of carbon black (CB)/HDPE composite, the negative temperature coefficient (NTC) effect of the MWNT/HDPE composite at temperature above the melting temperature of HDPE was much less obvious and could be further eliminated after 80 kGy gamma-ray irradiation. The mechanism of the PTC and NTC effects in MWNT/HDPE composites was discussed. (C) 2005 American Institute of Physics.
Local stability analysis and domain of attraction estimation for a class of uncertain nonlinear discrete‐time systems

This paper proposes a linear matrix inequality based method for the estimation of domain of attraction for a class of discrete‐time nonlinear systems subject to uncertain constant parameters. Recursive algebraic representations of the system dynamics and of the Lyapunov stability conditions are applied to obtain convex conditions which guarantee the system robust local stability while providing an estimate of the domain of attraction. A large class of discrete‐time nonlinear systems and of Lyapunov functions can be embedded in the proposed methodology including the whole class of regular rational functions of the system state variable and uncertain parameters. Numerical examples illustrate the application of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.
Completion of real fans and Zariski-Riemann spaces

Given a real fan in a real space consisting of real convex polyhedral cones, we construct a complete real fan which contains the fan, by two completely different methods. The ﬁrst one is purely combinatorial and a proof of a related version was sketched earlier by Ewald. The second one is based on Nagata’s method of imbedding an abstract variety into a complete variety. For the second method, we introduce the theory of Zariski-Riemann space of a fan.
Photoelectron Spectroscopic Study of Electronic Structures of L-Cysteine

The valence band structure of L -cysteine films was investigated by ultraviolet photoelectron spectroscopy (UPS) in the photon energy range of 40–100 eV. Smooth thin films were produced by vacuum evaporation and characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and Raman scattering spectroscopy. The photon energy dependence of the UPS spectra indicates that electronic states close to the valence band maximum may be attributed to sulfur, while the other states in the higher-binding-energy region may be attributed to carbon, nitrogen, and oxygen. Molecular orbital calculation was performed on seven possible geometries of L -cysteine. The observed UPS spectrum is in good agreement with the simulated one in terms of the C3 geometry of L -cysteine. It is concluded that the sulfur-originated electronic state is located at the valence-band maximum, indicating that cysteine is one of the useful and promising materials in future bioelectronics.
Phase diagram for droplet impact on superheated surfaces

We experimentally determine the phase diagram for impacting ethanol droplets on a smooth, sapphire surface in the parameter space of Weber number $\mathit{We}$ versus surface temperature $T$ . We observe two transitions, namely the one towards splashing (disintegration of the droplet) with increasing $\mathit{We}$ , and the one towards the Leidenfrost state (no contact between the droplet and the plate due to a lasting vapour film) with increasing $T$ . Consequently, there are four regimes: contact and no splashing (deposition regime), contact and splashing (contact–splash regime), neither contact nor splashing (bounce regime), and finally no contact, but splashing (film–splash regime). While the transition temperature $T_{L}$ to the Leidenfrost state depends weakly, at most, on $\mathit{We}$ in the parameter regime of the present study, the transition Weber number $\mathit{We}_{C}$ towards splashing shows a strong dependence on $T$ and a discontinuity at $T_{L}$ . We quantitatively explain the splashing transition for $T<T_{L}$ by incorporating the temperature dependence of the physical properties in the theory by Riboux & Gordillo (Phys. Rev. Lett., vol. 113(2), 2014, 024507; J. Fluid Mech. , vol. 772, 2015, pp. 630–648).
Trace of planetary nebula evolution by distance-independent parameters

Using existing infrared and radio data on a sample of 432 planetary nebulae, we derived a number of distance-independent parameters for comparison with evolutionary models of planetary nebulae. We find that many of the observed properties of planetary nebulae can be explained by current central star evolutionary models, even if the time scales are subject to significant change by a factor of up to an order of magnitude. Specifically, we find that the evolutionary tracks are well separated in the radio surface brightness-central star temperature plane, therefore allowing us to determine the core mass of individual planetary nebulae. We also obtain the luminosity and gravity of the central stars of individual nebulae, from their temperature and core mass, without relying on the distance assumptions. We find that our results of the core mass are in good agreement with those of Mendez et al. (1992) and Tylenda et al. (1991). A systematic, large discrepancy is found between the luminosity found in this work and that found by Gathier and Pottasch (1986).
Y(4260) and possible charmonium assignment

The newly reported Y(4260) becomes the second most massive state in the charmonium family. We argue that it displaces the {psi}(4415) as the (largely) 4s vector charmonium state, recall s-d wave interference to explain the lack of a signal in e{sup -}e{sup +} {yields} hadrons and suggest some further study avenues that can exclude exotic meson assignments. The absence of a J/{psi} KK mode can be understood, beyond phase space suppression, to be a consequence of chiral symmetry. We also provide a model calculation in this sector showing that, although forcing the fit somewhat (which suggests a small sea quark wavefunction component), the state can be incorporated in a standard scheme.
Energy Supply and Photon Emission by Solitons in Alpha-Helical Proteins

We study the nonlinear mechanism of energy supply in alpha-helical proteins with three polypeptide spines bound by hydrogen bonds. Taking into account the electron-phonon interaction results in the self-trapping of excitations in localized soliton-like states. The important role of the helical symmetry of macromolecules is elucidated for the formation, stability, and dynamical properties of Davydov's solitons. It is shown that the soliton with the lowest energy has an inner structure with the many-hump envelope. The total probability of the excitation in the helix is characterized by interspine oscillations with the frequency of oscillations proportional to the soliton velocity. These oscillations of charged soliton lead to the electromagnetic radiation of characteristic frequencies. The radiative lifetime of a hybrid soliton is calculated and shown to exceed the lifetime of an excitation on an isolated peptide group by several orders of magnitude.
The effects of small ice crystals on cirrus infrared radiative properties

Abstract Using a model that combines single-scattering properties for spheroidal and hexagonal ice crystals, the thermal infrared radiative properties of cirrus clouds have been investigated. Infrared scattering and absorption properties for randomly oriented spheroids and hexagons are parameterized based on the anomalous diffraction theory and a geometric ray-tracing method, respectively. Using observed ice crystal size distributions, upwelling radiances at the top of cirrus cloudy atmospheres have been computed. Results show that the presence of small ice crystals can produce significant brightness temperature differences between two infrared wavelengths in the 10-μm window. Theoretical results have been compared with observed brightness temperature differences between 8.35 and 11.16 μm and between 11.16 and 12 μm. The observed values were obtained from the High-Spectral Resolution Interferometer Sounder. It is shown that the use of the present nonspherical model for ice crystals in radiative transfer c.
Recursively categorical linear orderings

A recursive structure C is recursively categorical if every recursive structure i' isomorphic to C is recursively isomorphic to (i. We classify the recursively categorical linear orderings as precisely those recursive linear orderings L which have only finitely many elements with an immediate successor. A structure (E over a recursive language e is said to be recursive if A, the domain of i, is recursive and there is a uniform effective procedure for deciding whether 6& satisfies any atomic formula T(ao, . . , an) with ao,. , a, C A. Two recursive structures 6i and 6W' are recursively isomorphic, denoted 6i d r 6W, if there is a partial recursive isomorphismf from 6i onto 6'. We say a recursive structure 2i is recursively categorical if any recursive structure 6' isomorphic to 6i is recursively isomorphic to 6i. The notion of recursive categoricity was first defined for groups by Mal'cev [3] and is referred to in the Soviet literature as autostability. In recent years, the notion of recursive categoricity has been studied widely in the literature. General semantic conditions for when decidable models are recursively categorical was given by Nurtazin [4] and similar results were found by Ash and Nerode for models in which one can effectively decide all El-formulas. The recursively categorical structures for various theories have been classified, including: Boolean algebras, independently by Goncharov [2] and La Roche [5] (the first full proof in the literature is found in Remmel [7]); Boolean algebras with additional predicates for atoms or atoms and atomless elements by Remmel [8], [9]; Abelian p-groups by Smith [10]; and decidable dense two-dimensional partial orderings by Remmel and Manaster [4]. The main result of this paper is the classification of the recursively categorical recursive linear orderings as precisely those recursive linear orderings L which have only finitely many elements which have immediate successors. We end the paper with a brief discussion of the relationship between our classification and the known classification of recursively categorical Boolean algebras. Finally we should note that Theorem 1 to follow does not follow from the general work of Nurtazin or Ash and Nerode since Goncharov [2] has constructed recursive linear orderings K such that one cannot effectively decide the El-formulas in any recursive linear ordering isomorphic to K. Given a linear ordering L = , we say the pair (x, y) is a successivity of L, written x -*L Y, if x <L y and there is no z E A such that x <L Z <L Y. We let Received by the editors September 29, 1980. 1980 Mathematics Subject Classification. Primary 02F27; Secondary 06A05. Partially supported by NSF Grant MCS79-03406. ( 1981 American Mathematical Society 0002-9939/81 /0000-0485/$02.2 5
A weak type (1,1) estimate for a maximal operator on a group of isometries of a homogeneous tree

We give a simple proof of a result of R. Rochberg and M. Taibleson [6] that various maximal operators on a homogeneous tree, including the Hardy–Littlewood and spherical maximal operators, are of weak type (1, 1). This result extends to corresponding maximal operators on a transitive group of isometries of the tree. Dedicated to the memory of Andrzej Hulanicki