Miracle-dz/UniFAR-FTUs huggingface dataset:
Structure and energetics of Cu N clusters with ( 2 ⩽ N ⩽ 150 ) : An embedded-atom-method study

We use the embedded-atom method (EAM) in the version of Daw, Baskes, and Foiles (DBF) to determine the three most stable isomers of ${\mathrm{Cu}}_{N}$ clusters with $N$ from 2 to 150. Randomly generated initial configurations are optimized with the variable metric/quasi-Newton method combined with our own Aufbau/Abbau algorithm for searching the global minima. A detailed comparison is made for clusters with up to 60 atoms obtained with the DBF and the Voter-Chen (VC) versions of the EAM, the many-body Gupta, and the Sutton-Chen 9-6 potentials. Although the two EAM potentials have completely different parametrizations, they yield clusters that are structurally and energetically almost identical. On the other hand, the Sutton-Chen potential strongly overestimates the binding energy of the dimer and the small copper clusters with up to 15 atoms, and therefore, yields clusters with shorter bond lengths. For DBF clusters with up to 150 atoms we analyze many structural and energetic properties such as the overall shape, the construction of atomic shells, the similarity of the clusters with fragments of the fcc crystal or of a large icosahedral cluster, and whether the $N$-atom cluster resembles the $(N\ensuremath{-}1)$-atom one with an extra atom added. The most stable clusters have high symmetry, such as the magic-sized ${\mathrm{Cu}}_{55}$ and ${\mathrm{Cu}}_{147}$ that are the second and third Mackay icosahedra, where the latter was obtained for the first time in a completely unbiased structure optimization. The cluster growth is predominantly icosahedral, with islands of fcc, tetrahedral, and decahedral growth.
Re‐ordered electron data in the low‐latitude boundary layer

We have made a complete survey of all electron data recorded during low-latitude boundary layer crossings of the AMPTE-UKS spacecraft. In 27 of the 31 cases there is a clear anticorrelation between the density and the mean energy of the electrons during the transition across the boundary layer. The simplest interpretation of this anticorrelation is that, in the majority of cases, there is a smooth change of plasma state between the bounding solar and terrestrial plasmas, and that the abrupt changes frequently seen in time series data arise from boundary layer motions. Our data indicate that there are always two distinct sections to the anticorrelation. We suggest that these represent two physically distinct regions within the boundary layer and indicate how electron density and energy might vary across them. We briefly discuss an alternative interpretation in which filaments of magnetosheath plasma penetrate the boundary layer. We show that our results provide a constraint on such a model.
Convexity of solutions of semilinear elliptic equations

On considere le probleme elliptique suivant Δu=f(u) dans Ω, u=M sur ∂Ω ou Ω est un domaine convexe de R 2 et M est soit une constante reelle soit +∞. On etablit que, pour une bonne fonction monotone g(t), pout toute solution u on a g(u) est strictement convexe dans Ω
General reggeon vertex in dual theory

On the basis of Fubini and Veneziano's manifestly dual symmetric operator expression for a dual amplitude, we perform multiple-factorization of dual amplitude in Shapiro's general factorization scheme. In contrast with other works, our method of multiple-factorization is completely symmetric with respect to Reggeon legs. A new general form of Reggeon vertex is obtained, which includes Lovelace's vertex as a particular limiting case, and Olive's one as a special case. Our general Reggeon vertex has simple gauge and twisting transformation properties. The duality relation is satisfied with the KSV change of propagator variables, as an identity of, integrands.
Surface charging under pulsed laser ablation of solids and its consequences: studies with a continuum approach

Dynamics of electronic excitation, heating and charge-carrier transport in different materials (metals, semiconductors, and dielectrics) under femtosecond pulsed laser irradiation is studied based on a unified continuum model. A simplified drift-diffusion approach is used to model the energy flow into the sample in the first hundreds of femtoseconds of the interaction. The laser-induced charging of the targets is investigated at laser intensities slightly above the material removal threshold. It is demonstrated that, under near-infrared femtosecond irradiation regimes, charging of dielectric surfaces causes a sub-picosecond electrostatic rupture of the superficial layers, alternatively called Coulomb explosion (CE), while this effect is strongly inhibited for metals and semiconductors as a consequence of superior carrier transport properties. Various related aspects concerning the possibility of CE for different irradiation parameters (fluence, wavelength and pulse duration) as well as the limitations of the model are discussed. These include the temporal and spatial dynamics of charge-carrier generation in non-metallic targets and evolution of the optical (reflection and absorption) characteristics. A controversial topic concerning CE probability in laser irradiated semiconductor targets is also a subject of this work.
One Concept and Two Narrations: The Case of the Logarithm

Abstract Through an account of the history of exponential functions as presented in traditional calculus textbooks, I present my observations and remarks on the spiral development of the concept, and my concerns about the general presentations of the subject. In this article I emphasize how the different arrangements and sequencing of the subjects required for the development of the concept of the logarithm would lead to different definitions. A slow process that requires gradual maturity and readiness precedes the formal foundation of the concept. One statement can be considered a definition according to one arrangement, and a theorem according to another arrangement. This study is primarily addressed to teachers, or to mathematics education students in a content-based mathematics education class.
The mineralogy and crystal chemistry of deep-sea manganese nodules, a polymetallic resource of the twenty-first century

The relatively high concentrations of cobalt, nickel, and copper in deep-sea manganese nodules, such as those occurring on the sea-bed beneath the north equatorial Pacific Ocean, indicate that these marine sediments are potential ore deposits. In order to explain the strong enrichments of Ni, Cu, and Co in the nodules, the crystal chemistries and structures of the host manganese oxide minerals must be understood. Over twenty manganese(IV) oxide minerals are known, but only three predominate in manganese nodules. They are todorokite, birnessite, and delta-MnO2. All MnIV oxides contain edge-shared MnO6 octahedra linked in diverse ways, leading to a hierarchy of structure-types somewhat resembling the classification of silicates. Todorokite is deduced to contain chains of edge-shared MnOe octahedra enclosing huge tunnels, thus resembling hollandite and psilomelane. Birnessite has a layered structure with essential vacancies in the sheets of edge-shared MnO6 octahedra, while δ-MnO2 is a disordered birnessite. The uptake of Co into manganese nodules involves replacement of low-spin Co3+ for Mn4+ ions in the structures, whereas Ni2+ and Cu2+ substitute for Mn2+ ions in octahedra located in the chains or between layers of edge-shared MnO6 octahedra.
YBCO step-edge junctions with high IcRn

Step-edge junctions represent one type of grain boundary Josephson junction employed in high-temperature superconducting junction technology. To date, the majority of results published in the literature focus on [001]-tilt grain boundary junctions (GBJs) produced using bicrystal substrates. We investigate the step morphology and YBCO (yttrium barium copper oxide) film structure of YBCO-based step-edge junctions on MgO [001] substrates which structurally resemble [100]-tilt junctions. High-resolution electron microscopy reveals a clean GBJ interface of width ∼ 1 nm and a single junction at the top edge. The dependence of the transport properties on the MgO step-edge and junction morphology is examined at 4.2 K, to enable direct comparison with results for other junction studies such as [001]-tilt and [100]-tilt junctions and building on previously published 77 K data. MgO step-edge junctions show a slower reduction in critical current density with step angle compared with [001]-tilt junctions. For optimized step parameters, transport measurements revealed large critical current and normal resistance (IcRN) products (∼3–5 mV), comparable with the best results obtained in other kinds of [100]-tilt GBJs in YBCO at 4.2 K. Junction-based devices such as SQUIDs (superconducting quantum interference devices) and THz imagers show excellent performance when MgO-based step-edge junctions are used.
Surface Microphysical Observations within East Coast Winter Storms on Long Island, New York

AbstractSurface observations of ice habit and degree of riming were measured for 12 cyclone events over 3 winter seasons at Stony Brook, New York, on the northeast coast of the United States. A total of 205.6 cm of snow accumulated during these storms, with an average degree of riming of 1.25 (out of 5) and snow-to-liquid ratio ranging from 3:1 to 17:1. There were consistent spatial patterns of habit and riming intensity relative to the cyclone structure. Cold-type habits (side planes and bullets) commonly occurred within the outer comma head to the north and northeast of the cyclone center. In the middle of the comma head, moderately rimed dendrites, plates, and needles were observed. Close to the cyclone center, heavy riming was observed with needles and graupel. The western quadrant of the comma head had primarily plates and dendrites with little to no riming. Periods of light riming and high snow–liquid ratios (≥13:1) are dominated by cold-type habits, dendrites, and plates and have similar vertical m.
A simple plasma diagnostic based on processing the electrical signals from coaxial discharges

A technique for the determination of the inductance evolution in coaxial discharges based on measurements of the voltage between the electrodes and of the discharge current time derivative is presented and discussed. The technique is applied to measurements performed in a 5.7 kJ plasma focus device operating with deuterium filling in the 1–6 mbar range (which is the neutron yield range) and the obtained results are in good agreement with the expected evolution of a current sheet within the electrodes system.
On the Optimality of Structured Policies in Countable Stage Decision Processes. II: Positive and Negative Problems

The analysis of structured countable stage decision processes, initiated in Porteus [11], is continued. The standard models of positive and negative dynamic programming are given in this context, thus extending these results to criteria other than the usual expected sum of rewards, such as expected utility criteria, certain stochastic games, risk sensitive Markov decision processes, and maximin criteria.For positive problems, (what are called) unimprovable strategies are optimal and the optimal value sequence is the least solution of the optimality equations exceeding an obvious lower bound. For negative problems, conserving strategies are optimal, and if one strategy is a one-step improvement on another, then it nets a greater value. (This rules out cycling in the strategy iteration procedure.) Also, transfinite methods are used to prove that the optimal value sequence is the greatest solution of the optimality equations less than an obvious upper bound. We indicate how all these results can be extended .
Polarization effects in high-harmonic generation in the presence of static-electric field

We study the ellipticity dependence of the high-order harmonic generation (HOHG) when a static electric field is presented. Through investigating the corresponding classical trajectories of the electron for the harmonic generation. it is found that there exists two different mechanisms. For circularly polarized incident light the HOHG originates mainly from the recombination of the electrons to the nucleus after multiple returns. We also find that for the elliptical incidence HOHG, the application of a static electric field can generate harmonics far beyond the usual cutoff. [S1050-2947(99)04004-4].
Monte Carlo study of device characteristics of GaN-based avalanche photodiode devices

In this article, Monte Carlo method is used to study the characteristics of gallium nitride (GaN). Impact ionization is treated as an additional scattering mechanism, which is described by the Keldysh formula with the parameters determined by fitting the simulated results to the numerical calculation results. Based on simplified model, results of velocity overshoot and impact ionization rate of both carriers are calculated and analyzed. In addition, we get the device characteristics associated with impact ionization, i.e., gain, noise, and bandwidth (both electron- and hole-injected cases), which is compared to the reported experimental data and conventional theories. Moreover, we contrast the simulated device characteristics of GaN and the performance of several conventional materials.
Growth and characterization of bulk InGaN films and quantum wells

InGaN bulk layers and single quantum wells were grown by atmospheric pressure metalorganic chemical vapor deposition on c‐plane sapphire. We have found that the incorporation efficiency of indium into InGaN epitaxial layers is strongly dependent on the growth rate of the films. Narrow and bright band edge related luminescence was observed for InGaN films up to an indium content of 20% grown at 700 °C. In0.16Ga0. 84N single quantum wells with graded InxGa1−xN barriers showed intense luminescence, with an energy shift towards shorter wavelength with decreasing quantum well thickness. The photoluminescence full width at half‐maximum of the 50 A thick well was as low as 7.9 nm (59 meV) at 300 K.
A Comparative Study of Measures of Partial Knowledge in Multiple-Choice Tests

A common belief among many test experts is that measurements obtained from multiple-choice (MC) tests can be improved by using evidence about partial knowledge. A large number of methods designed to extract such information from direct reports provided by examinees have been developed over the last 50 years. Most methods require modifications in test instructions, response modes, and scoring rules. These testing methods are reviewed and the results of a large-scale empirical study of the most promising among them are reported. Seven testing methods were applied to MC tests from four different content areas using a between-persons design. To identify the most efficient methods and the optimal conditions for their application, the results were analyzed with respect to six different criteria. The results showed a surprisingly large tendency on the part of the examinees to take advantage of the special features of the alternative methods and indicated that, on average, high ability examinees were better judges of their level of knowledge and, consequently, could benefit more from these methods. Systematic interactions were found between the testing method and the test content, indicating that no method was uniformly superior.
On the phase sequence of antiferroelectric liquid crystals and its relation to orientational and translational order

The substance MHPOBC is the oldest and still most important reference antiferroelectric liquid crystal (AFLC). There is still considerable controversy concerning the correct phase designations for this material and, in particular, about the presence or absence of SmC* in its phase sequence. By means of dielectric spectroscopy and polarizing microscopy, we show that whereas the pure compound lacks the SmC* phase, this phase rapidly replaces the SmC*β subphase through the reduced purity resulting from temperature-induced chemical degradation which is hard to avoid under standard experimental conditions. X-ray investigations furthermore show that this change in phase sequence is coupled to a decrease in translational order. This explains the large variations in the reported phase sequence and electro-optic behaviour of MHPOBC, in particular concerning the SmC*β phase which has been said to exhibit ferro-, ferri- as well as antiferroelectric properties. It is likely that the sensitivity of the AFLC phase sequence to sample purity is a general property of AFLC materials. We discuss the importance of optical and chemical purity as well as tilt and spontaneous polarization for the observed phase sequence and propose that one of the key features determining the existence of the different tilted structures is the antagonism between orientational (nematic) and translational (smectic) order. The decreased smectic order (increased layer interdigitation) imposed by chemical impurities promotes the synclinic SmC* phase at the cost of the AFLC phases SmC*α, SmC*β, SmC*γ and SmC*a. We also propose that the SmA* phase in FLC and AFLC materials may actually have a somewhat different character and, depending on its microstructure, some of the tilted phases can be expected to appear or not to appear in the phase sequence. AFLC materials exhibiting a direct SmA* -SmC*a transition are found to be typical ‘de Vries smectics’, with very high orientational disorder in the SmA* phase. Finally, we discuss the fact that SmC*β and SmC*γ have two superposed helical superstructures and explain the observation that the handedness of the large scale helix may very well change sign, while the handedness on the unit cell level is preserved.
Weak efficiency in multiobjective quasiconvex optimization on the real-line without derivatives

This article deals with the problem of the existence of a weakly efficient solution to quasiconvex vector optimization problems in a finite dimensional setting on the real-line. This consideration is motivated by algorithmic purposes, because it is expected that, like in scalar minimization, one must solve a one-dimensional problem to find the next iterate. We start by recalling a notion of nonconvexity weaker than quasiconvexity for vector functions introduced ealier by one of the authors in a previous paper. Afterwards, we characterize the nonemptiness and/or compactness of the weakly efficient solution set. Then, this set is described as much as possible in the multiobjective case, and the bicriteria problem is carefully analysed when each component is lower semicontinuous and quasiconvex. Several examples showing the applicability of our results are presented, and various algorithms are stated to compute the overall weakly efficient solution set.
An Insight into the Structural, Electronic and Transport Characteristics of XIn2S4 (X = Zn, Hg) Thiospinels using a Highly Accurate All-Electron FP-LAPW+Lo Method

The highly accurate full-potential linearized augmented plane wave plus local orbital method is employed to calculate the structural, electronic and transport properties of HgIn2S4 and ZnIn2S4. For ZnIn2S4, the calculated In—S bond length is in good agreement with the experimental data. Bulk moduli results suggest that ZnIn2S4 can afford more compressional effects than HgIn2S4. The present study confirms that both HgIn2S4 and ZnIn2S4 are indirect band gap materials with band gap values of 0.705 eV and 1.533 eV respectively. The localized region existing in the most bottom valance band of both materials splits into states by 1 eV energy difference under the spin orbital coupling effect. Contour plots of charge density predict that chemical bonding in these compounds is a mixture of ionic and covalent characteristics. Effective mass results reveal that mobility of charge carriers in ZnIn2S4 is greater than that in HgIn2S4.
Bandgap reduction responsible for the improved thermoelectric performance of bulk polycrystalline In2–xCuxSe3 (x = 0−0.2)

α-In2Se3 is of large bandgap (∼1.4 eV) semiconductor and its structure is based on two-layer hexagonally packed arrays of selenium atoms with 1/3 of the sites of indium atoms being empty. Here we report a bandgap Eg reduction due mainly to the formation of a Cu2Se slab in the host In2Se3, which is responsible for the remarkable improvement of thermoelectric performance of bulk polycrystalline In2−xCuxSe3 (x = 0.1–0.2). When x = 0.2 the dimensionless figure of merit ZT and power factor were increased by a factor of 2 and 3, respectively, at 846 K if compared to those of Cu-free In2Se3. Interestingly, an incorporation of Cu into the lattice of In2Se3 results in a change in morphology from amorphouslike structure represented by In2Se3 to a visible polycrystalline form attributed to partial crystallization of the structure. This change enhances lattice thermal conductivities κL over the very low values of In2Se3. However, the enhancement is only moderate because of the effective scattering of phonons in the p.
Positioning effects on quantum dot solar cells grown by molecular beam epitaxy

We report current-voltage and spectral response characteristics of high density InAs/GaAs quantum dot (QD) solar cells with different positions where dots are located. The short circuit current density (Jsc), open circuit voltage (Voc), and external quantum efficiency of these cells under air mass 1.5 are presented and compared with a GaAs reference cell. An extended photoresponse in contrast to the GaAs reference cell was confirmed for all these cells. The effect of inserting QD layers into emitter and base region on device performance is shown. The Jsc is reduced, while the Voc is maintained. The cell with QDs located toward the base side shows better performance, confirmed by both current-voltage and spectral response measurements.
FDTD analysis of the light propagation in the cones of the human retina: an approach to the Stiles–Crawford effect of the first kind

In this work, we analyse the propagation of light in the human retinal cones by the finite-difference time-domain method (FDTD) in cylindrical coordinates, for systems with axial symmetry or body of revolution (BOR). This work constitutes a preliminary approach to the study of the Stiles–Crawford effect of the first kind (SCE I), as a cone has been simulated, while the SCE I is a consequence of a large number of photoreceptors. The FDTD method enables a numerical resolution of Maxwell’s equations. With the computational implementation of these equations we have obtained, in the cone endface, the intensity patterns for different angles with which the light strikes the input side of the photoreceptor, and different wavelengths of incident light. In view of the results, the characteristics of fibre optics presented by the retinal cones remain valid, as does the goodness of the method and of the computational cone model that we have proposed. This work demonstrates, in short, the computational validity of our cone model as well as the power and versatility of the FDTD-BOR algorithm for the analysis and comprehension of the phenomenon of light propagation in retinal photoreceptors. It therefore offers broad possibilities in the field of research on visual processes, serving as support for analysis and interpretation of experimental measurements.
The molecular envelope of Mira

The CO J = 2 - 1 and J = 0 emission of the circumstellar envelope of Mira has been mapped. Three velocity components are found at 44.0, 46.8, and 48.1 km/s. The emission is interpreted as arising from a standard circumstellar envelope and a less extended bipolar outflow. The spherical circumstellar envelope has an expansion velocity of 3 km/s, a mass-loss rate of 1 x 10 to the -7th solar mass/yr, and a total molecular mass of 0.0004 solar mass. 29 refs.