Miracle-dz/UniFAR-FTUs huggingface dataset:
Extragalactic globular clusters. II, The M31 globular cluster system

Metallicities for 150 globular clusters associated with M31 are derived using the strengths of six absorption features in the cluster-integrated spectra. The properties of the M31 cluster system are very similar to those of the Galactic system. No dependence of metallicity on cluster luminosity is found. The number distribution as a function of metallicity is consistent with that of Galactic clusters. There is evidence for a weak metallicity gradient as a function of projected radius. The mean metallicity Fe/H is equal to -1.2, slightly higher than the mean for the Galactic system. 48 refs.
Non-Abelian structure of Yang-Mills theory and infrared-finite asymptotic states

The idea of Kulish and Faddeev for treating asymptotic dynamics is extended to derive a set of states with which the matrix element of quark scattering from a color-singlet external potential is shown to be free of the leading-order non-Abelian class of infrared divergences to fifth order in g.
Variable Stars and Data-Intensive Astronomy

Abstract Extensive discoveries of variable stars in ground-based photometric surveys and in observations from space missions that provide unprecedented accuracy demonstrate that, till the most recent time, we knew only a tiny fraction of all detectable variable stars of our Galaxy. As a result, our knowledge on stellar variability types, related physical processes, variable-star statistics turn out to be based on an unrepresentative sample and are expected to be radically revised in the near future. The flow of new discoveries results in quite difficult problems for catalogs of variable stars, making it impossible to proceed in their compilation in the traditional way. Regretfully, automatic solutions are still not completely satisfying. Though not able to suggest a perfect way out, we present our vision of the future of variable-star research.
Roughness of the Contact Line on a Disordered Substrate

We present results from an experimental study on the wetting properties of superfluid helium-4 on a cesium substrate with random disorder. We have measured the roughness exponents of the contact line, and found that they are in agreement with theoretical predictions. Furthermore, we have observed a strong increase of the contact line fluctuations near the wetting transition; this temperature dependence is consistent with the theory.
Malliavin Calculus and Euclidean Quantum Mechanics II. Variational Principle for Infinite Dimensional Processes

Abstract A class of time reversible non-stationary diffusion processes with values on the classical Wiener space is constructed. These processes should be relevant to ("2-dimensional") Euclidean quantum field theory since they generalize those constructed before for non-relativistic quantum mechanics, along the lines of a strategy suggested by Schrodinger. Those processes are shown to be characterized by a stochastic variational principle and provide a probabilistic representation of the solutions of some infinite-dimensional heat equation. The Feynman-Kac formula on the Wiener space needed for this construction is also proved.
High-temperature and low-threshold midinfrared interband cascade lasers

A broad-area midinfrared interband cascade (IC) laser has been demonstrated with a threshold current as low as ∼630A∕cm2 at 300K. Despite exhibiting a large specific thermal resistance (∼56Kcm2∕kW at 172K), the device delivered cw power near 200mW/facet at 500mA and at 83K and lased in cw mode up to 172K. A 0.5-mm-long laser delivered cw power of ∼253mW/facet at 400mA and at 82K, and had power efficiency as high as 26% at ∼80K. Narrow mesa stripe IC lasers had relatively higher threshold current density, yet lased at temperatures up to 237 and 350K in cw and pulsed modes, respectively. The feasibility of cw operation at higher temperatures and directions for improving IC laser performance are discussed based on the experimental data.
Low frequency noise in 4H-SiC metal oxide semiconductor field effect transistors

The low frequency noise was studied in 4H-SiC metal oxide semiconductor field effect transistors (MOSFETs) in the frequency range from 1 Hz to 100 kHz. 1/f (flicker) noise dominated in output noise over the entire frequency range and for a wide range of drain and gate biases. The dependence of the relative spectral noise density, SI/Id2, on the drain current, Id (at constant drain voltage, Vd), was qualitatively different from typical dependences for n-channel Si MOSFETs. In Si MOSFETs, in strong inversion, SI/Id2 usually decreases as ∼1/Id2 and tends to saturate in the subthreshold region, whereas in SiC MOSFETs under study, SI/Id2∝Id−0.5 for the currents varying from the deep subthreshold regime to the strong inversion. [Similar dependences were often observed in amorphous and polycrystalline thin film transistors (TFTs). ] The effective field effect mobility of 3–7 cm2/V s extracted from the measured I-V characteristics is almost as low as that in amorphous Si TFTs. This result might be explained by a high density of localized states near the conduction band in the thin ion implanted silicon carbide layer. The energy dependence of trap density responsible for the noise was extracted for the states located close to the bottom of conduction band.The low frequency noise was studied in 4H-SiC metal oxide semiconductor field effect transistors (MOSFETs) in the frequency range from 1 Hz to 100 kHz. 1/f (flicker) noise dominated in output noise over the entire frequency range and for a wide range of drain and gate biases. The dependence of the relative spectral noise density, SI/Id2, on the drain current, Id (at constant drain voltage, Vd), was qualitatively different from typical dependences for n-channel Si MOSFETs. In Si MOSFETs, in strong inversion, SI/Id2 usually decreases as ∼1/Id2 and tends to saturate in the subthreshold region, whereas in SiC MOSFETs under study, SI/Id2∝Id−0.5 for the currents varying from the deep subthreshold regime to the strong inversion. [Similar dependences were often observed in amorphous and polycrystalline thin film transistors (TFTs). ] The effective field effect mobility of 3–7 cm2/V s extracted from the measured I-V characteristics is almost as low as that in amorphous Si TFTs. This result might be explained by a h.
Computation of minimal-order state-space realizations and observability indices using orthogonal transformations

In this paper, an algorithm is presented for obtaining a minimal-order state-space realization of a strictly proper rational function matrix. The algorithm can also be used to compute the observability indices of any given state-space system. A controllable but unobservable state-space realization of the given rational function matrix is first obtained, by inspection. The algorithm then performs a sequence of simple coordinate transformations on the state vector of the system. The coordinate transformation matrices are orthogonal and are easily constructed from the system matrices. Each coordinate transformation operates on submatrices (of the state-space system matrices) of lower dimension than the preceding one. The sequence of coordinate transformations terminates after at most v 1 + 1 transformations, where v 1, is the maximal observability index of the state-space model. The observability indices of the system are also determined at this time. The transformed system matrices are obtained in a form wh.
Reducing electrical processing cost by optical bypass approach in packet ring networks

Packet Ring transport technology combines the simplicity of Ethernet and survivability of SONET and attracts more and more interests of researches. However, electrical processing cost will also be very high as data rate grows to gigabit level, which lowers its efficiency. This paper examines the value of optical bypass approach by minimizing the traffic to be processed in electrical domain. An Integer Linear Program (ILP) formulation is presented to solve this problem and results with different traffic patterns are given, which shows one more wavelength can bring notable electrical processing cost savings in the case of a small number of multiplexed wavelengths in one channel.
Experimental investigation of the motion of a bubble in a gradient of turbulence

The role of the turbulence-intensity gradient upon the motion of a bubble is investigated. Isolated bubbles are put into a turbulence field, which is isotropic and decreases exponentially in intensity in the z-direction. Experiments are carried out under microgravity conditions, so that the buoyancy is negligible. Bubbles are observed to move in the z-direction. Their mean velocity is found to result from a balance between the mean-pressure gradient and the Reynolds-stress gradient.
Geometric Theory of Foliations

I - Differentiable Manifolds. - II - Foliations. - III - The Topology of the Leaves. - IV - Holonomy and the Stability Theorems. - V - Fiber Bundles and Foliations. - VI - Analytic Foliations of Codimension One. - VII - Novikov's Theorem. - VIII - Topological Aspects of the Theory of Group Actions. - Appendix - Frobenius' Theorem. - 1. Vector fields and the Lie bracket. - 2. Frobenius' theorem. - 3. Plane fields defined by differential forms. - Exercises.
A full band Monte-Carlo study of carrier transport properties of InAlN lattice matched to GaN

The growing importance of In0:18Al0:82N stems from the fact that it can be grown lattice matched to GaN and for its potential applications in a large number of electronics and optoelectronics devices. In this work we employed a full band Monte-Carlo approach to study the carrier transport properties of this alloy. We have computed the temperature and doping dependent electron and hole mobilities and drift velocities. Furthermore, for both sets of transport coefficients we have developed a number of analytical expressions that can be easily incorporated in drift-diffusion type simulation codes.
Second Harmonic Generation in Barium Titanate Thin Films on Silica Glass by Corona Poling

Among potential inorganic thin films, perovskite-structured barium titanate (BaTiO3) is particularly attractive due to its large ferroelectric response and large optical nonlinear coefficients. SiO2 material is also important in semiconductor processing. Therefore, we study the nonlinear optical (NLO) thin film deposited on a SiO2 substrate. We report our investigation of a BaTiO3 thin film on a silica glass (SiO2) substrate grown by rf magnetron sputtering. We measured the second-harmonic generation (SHG) and calculated the second-order nonlinear optical coefficients from the BaTiO3/glass by using the Maker fringes technique. From our experimental results, we found that by applying corona poling, the nonlinear optical coefficients in BaTiO3/glass can be increased. The SHG of the nonlinear thin film by poling is dependent on temperature.
A Dynamic Decision Model Applied to Hurricane Landfall

Abstract The decision to prepare for an oncoming hurricane is typically framed as a static cost:loss problem, based on a strike-probability forecast. The value of waiting for updated forecasts is therefore neglected. In this paper, the problem is reframed as a sequence of interrelated decisions that more accurately represents the situation faced by a decision maker monitoring an evolving tropical cyclone. A key feature of the decision model is that the decision maker explicitly anticipates and plans for future forecasts whose accuracy improves as lead time declines. A discrete Markov model of hurricane travel is derived from historical tropical cyclone tracks and combined with the dynamic decision model to estimate the additional value that can be extracted from existing forecasts by anticipating updated forecasts, rather than incurring an irreversible preparation cost based on the instantaneous strike probability. The value of anticipating forecasts depends on the specific alternatives and cost profile o.
Simulating quantum transport in nanoscale transistors: Real versus mode-space approaches

In this article, we present a computationally efficient, two-dimensional quantum mechanical simulation scheme for modeling electron transport in thin body, fully depleted, n-channel, silicon-on-insulator transistors in the ballistic limit. The proposed simulation scheme, which solves the nonequilibrium Green’s function equations self-consistently with Poisson’s equation, is based on an expansion of the active device Hamiltonian in decoupled mode space. Simulation results from this method are benchmarked against solutions from a rigorous two-dimensional discretization of the device Hamiltonian in real space. While doing so, the inherent approximations, regime of validity and the computational efficiency of the mode-space solution are highlighted and discussed. Additionally, quantum boundary conditions are rigorously derived and the effects of strong off-equilibrium transport are examined. This article shows that the decoupled mode-space solution is an efficient and accurate simulation method for modeling e.
Searching for Alternative Splicing With a Joint Model on Probe Measurability and Expression Intensities

The exon tiling array offers a high throughput technology to search for aberrant splicing in biomedical research, but few methods of analysis for splicing detection have been tested both statistically and empirically. Noisy measurements on nonresponsive probe selection regions and outlying intensities at some of the samples tend to distort model-based assessments. We propose a robust analysis of variance approach that incorporates an informative model on probe measurability and uses median regression rank scores for better reliability in alternative splicing detection. We study the validity and effectiveness of our proposed approach in contrast with some of the existing methods through an empirical investigation of a brain cancer experiment, where a set of biologically validated genes for splicing and nonsplicing are available. Our study demonstrates favorable performance of the proposed ranking method, but shows that analysis of statistical significance cannot be trusted from any conventional use of p-values. We warn of any routine attempt to interpret p-values and their derivatives in model-based detection of alternative splicing.
Students' difficulties with energy and related concepts

A questionnaire administered to 75 pupils in the beginning of the lower sixth form showed that a high percentage do not understand some of the key concepts of energy. Little or no correlation was found between answers to questions involving the application of qualitative knowledge and understanding and those involving quantitative reasoning. Suggestions are made on how the situation might be improved.
Images of four compact steep-spectrum quasars with a resolution of 20 milliarcseconds at 329. 1 MHz

Four compact steep-spectrum quasars (3C 48, 3C 147, 3C 309.1, and 3C 380) have been mapped with a resolution of 20 mas at 329 MHz. The structures of all four objects are asymmetric and complex, but they are shown here to be consistent with a basic one-sided jet morphology. In this, they are quite similar to other classes of radio sources; however, their small scales and convoluted structures suggest that in these objects, other factors such as the interaction with the interstellar medium and/or variations in the initial jet direction significantly affect the morphology. 43 refs.
The entry of aerosols into sampling tubes and heads

No general solution exists of the very complicated problem of aerosol sampling. In this paper the problem is broken down into sampling with a thin-walled tube and sampling with a bulky head. Tube sampling can be classified into `small tubes', which give the same results independent of their orientation, and `large tubes' where there is a change of sampling efficiency when the direction of the tube is altered. The limits of radius of a `small tube' sampling with an efficiency near to 100% are laid down in terms of particle size and suction speed; tables are given for evaluating the sampling efficiency in a wind. Calm air is defined by the wind speed being less than a value which is dependent on the sampling speed and particle size. The sampling efficiency of a `large tube' may depend on its orientation owing to the fall of particles due to gravity or to a wind blowing past the tube. Isokinetic sampling is necessary to obtain correct samples in strong winds; the effect on efficiency of sampling due to departure from the isokinetic conditions is discussed. The conditions are deduced for accurate sampling with a bulky suction head containing a small orifice: if the orifice faces downwards a critical suction speed exists below which no sample is obtained; at higher speeds sampling is selective and depends on the falling speed of the particles. When a bulky head is used in a cross wind there is no effect due to wind when the orifice is in the top. For a downwards facing orifice the effect of wind is to cause sampling to start at a lower rate of suction and to be more efficient at lower rates of suction. At high rates of suction the wind has no effect.
Shockley-Queisser Detailed Balance Efficiency Limit for Nanowire Solar Cells

III-V semiconductor nanowire arrays show promise as a platform for next-generation solar cells. However, the theoretical efficiency limit for converting the energy of sunlight into electrical energy in such solar cells is unknown. Here, we calculate through electromagnetic modeling the Shockley-Queisser efficiency limit for an InP nanowire array solar cell. In this analysis, we calculate first from the absorption of sunlight the short-circuit current. Next, we calculate the voltage-dependent emission characteristics of the nanowire array. From these processes, we identify how much current we can extract at a given voltage. Finally, after constructing this current-voltage (IV) curve of the nanowire solar cell, we identify from the maximum power output the maximum efficiency. We compare this efficiency of the nanowire array with the 31.0% efficiency limit of the conventional InP bulk solar cell with an inactive substrate underneath. We consider a nanowire array of 400 nm in period, which shows a high short-circuit current. We optimize both the nanowire length and diameter in our analysis. For example, nanowires of 4 mu m in length and 170 nm in diameter produce 96% of the short-circuit current obtainable in the perfectly absorbing InP bulk cell. However, the nanowire solar cell emits fewer photons than the bulk cell at thermal equilibrium, especially into the substrate. This weaker emission allows for a higher open circuit-voltage for the nanowire cell. As an end result, nanowires longer than 4 mu m can actually show, despite producing a lower short-circuit current, a higher efficiency limit, of up to 32.5%, than the bulk cell.
Nozzle flow separation

During the sea-level ignition process of rocket motors, the nozzle is subjected to an overexpanded e ow condition that can cause high side loads. Prediction of the symmetrical separation location is the e rst key step to a determination of the range of possible side-load magnitudes. The mechanisms responsible for causing the e ow to separate from the nozzle wall are demonstrated, and the theory for a new solution of the separation location is presented. The model is also correlated with historical rocket data, a new approximate solution, and an empirical curve e t that has been in use for 35 years. Nomenclature A = cross-sectional area of nozzle B = constant in approximate solution C = constant in Schilling curve e t CD = discharge coefe cient E = exponent in Schilling curve e t F = thrust M = Mach number P m = mass e ow rate p = pressure V = velocity ® = ratio of Mach disk area to nozzle area at separation point AMd=A3
Fabrication of High-Intensity Light-Emitting Diodes Using Nanostructures by Ultraviolet Nanoimprint Lithography and Electrodeposition

Antireflection nanostructures for GaN light-emitting diodes (LEDs) were fabricated by reactive ion etching (RIE) using Ni as an etching mask. The Ni mask was formed by electrodeposition in combination with ultraviolet nanoimprint lithography (UV-NIL). The antireflection nanostructures of 600 nm in depth, 300 nm in diameter, and 500 nm in pitch were fabricated on a GaN substrate. The radiant intensity of the LEDs was increased 1.5 times compared to that of a conventional LED. Since this method enables the fabrication of wafer-level GaN nanostructures with a low cost process, it is applicable to the fabrication of photonic crystals.
Electromagnetic-induced transparency of Wannier-Mott excitons

We predict a remarkable quenching of the absorption due to electromagnetic-induced transparency in an undoped bulk semiconductor. For free-exciton lines the effect is expected to be as large as that observed in atomic systems. The conditions for its occurrence are determined and numerical estimates are presented for the specific case of the yellow exciton of
Resistance of copper nanowires and comparison with carbon nanotube bundles for interconnect applications using first principles calculations

We have studied the electronic properties and the band structure of copper nanowires for various diameters using first principles density functional methods and a supercell approach. The resistances of copper nanowires were computed on the basis of the Landauer formalism and compared with those obtained from an empirical approach. The fundamental resistances of small copper nanowires (∼60 nm diameter) are found to be larger than those predicted by Ohm’s law. In parallel, we have computed the fundamental resistances for bundles of single walled carbon nanotubes and compared them with that of a single copper wire of similar dimensions. We find that the resistance of carbon nanotube bundles is smaller than that of the copper wires for dimensions below 60 nm. Our results are discussed in light of recent experiments.
Incidence angle dependence of Langmuir turbulence and artificial ionospheric layers driven by high-power HF-heating

We have numerically investigated the development of strong Langmuir turbulence (SLT) and associated electron acceleration at different angles of incidence of ordinary (O) mode pump waves. For angles of incidence within the Spitze cone, the turbulence initially develops within the first maximum of the Airy pattern near the plasma resonance altitude. After a few milliseconds, the turbulent layer shifts downwards by about 1 km. For injections outside the Spitze region, the turning point of the pump wave is at lower altitudes. Yet, an Airy-like pattern forms here, and the turbulence development is quite similar to that for injections within the Spitze. SLT leads to the acceleration of 10–20 eV electrons that ionize the neutral gas thereby creating artificial ionospheric layers. Our numerical modeling shows that most efficient electron acceleration and ionization occur at angles between the magnetic and geographic zenith, where SLT dominates over weak turbulence. Possible effects of the focusing of the electromagnetic beam on magnetic field-aligned density irregularities and the finite heating beam width at the magnetic zenith are also discussed. The results have relevance to ionospheric heating experiments using ground-based, high-power radio transmitters to heat the overhead plasma, where recent observations of artificial ionization layers have been made.