Miracle-dz/UniFAR-FTUs huggingface dataset:
Light Extinction by Aerosols during Summer Air Pollution

Abstract In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band λ440–870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99% of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 μm. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend an several aerosol parameters, but it is difficult to .
Saturated behavior of the gyrotron backward-wave oscillator

: Physical processes in the gyrotron backward-wave oscillator (gyro-BWO) are investigated theoretically. Results indicate highly current-sensitive field profiles and hence sharply contrasting linear and saturated behaviors. The linear field extends over the entire structure length, whereas the saturated profile depends strongly on the energetics in the internal feedback loop. It is shown that this distinctive feature substantially influences the basic properties of the gyro-BWO including the start-oscillation current, efficiency, power scaling, and stability of tuning.
Rigorous evaluation of the input impedance of a sleeve monopole by modal-expansion method

A rigorous modal-expansion analysis is developed for obtaining the current distribution and input impedance of a sleeve-monopole antenna fed through an infinite ground plane by a coaxial line. A "perfectly matched boundary," which is simply the combination of an electric wall and a magnetic wall, is initially proposed to facilitate the modal-expansion analysis. The walls are parallel to the ground plane at a variable height above it. Expansion coefficients of the electromagnetic fields are then determined by enforcing the boundary conditions at conducting surfaces and regional interfaces. Numerical results for the current distribution and input impedance of the sleeve monopole are presented and compared with available data in the literature. Very good agreement is observed. Also examined are the radiation pattern for different sleeve lengths and the effects of the length and finite thickness of the sleeve conductor on the antenna's input impedance.
Light Emitting Diode with Charge Asymmetric Resonance Tunneling

We suggest a system of two wells connected with Charge Asymmetric Resonance Tunneling (CART) as a basic element of light emitting diode (LED) structure for semiconductors with different masses of electrons and holes. The system consists of an emitter of electrons, an emitter of holes and an active layer. The hole emitter is coupled with the active in such a way that holes can be freely supplied into the active layer without a barrier. The electron emitter is coupled to the active layer via a barrier. The barrier design uses the charge asymmetric resonance tunneling phenomenon which allows to make the barrier transparent for electrons and blocking for holes. Advantages of this design are: the increased capture efficiency of the electrons into the active layer due to direct resonance tunneling of the electrons from the electron emitter on bound electron level in the active quantum well, the suppression of electron leakage into the hole emitter, the elimination of the parasitic light generated outside the active layer, and the electron emitter acts also as a good current spreading layer. First results of experimental investigation and theoretical modeling of the CART LED devices are reported.
Heavily Carbon Doped Base InP/InGaAs Heterojunction Bipolar Transistors Grown by Two-Step Metalorganic Chemical Vapor Deposition

A novel growth procedure for realizing high hole concentrations in the C-doped base layers of InP/InGaAs heterojunction bipolar transistors (HBTs) is presented. The H out-diffusion behavior from the epi-layer in relation to the cap layer thickness is investigated in detail. A relatively thin n-InP cap layer is found to be nearly transparent to out-diffusion of H at a relatively high annealing temperature of 550° C and to act as a barrier to re-hydrogenation during re-growth at 450° C. Using this non-reciprocal feature of thin n-InP cap layers with respect to hydrogen permeability, hydrogen was annealed out from the base layer outside the growth chamber, and then the rest of emitter and cap layers were re-grown without significant re-hydrogenation. The fabricated HBT has a base current ideality factor close to unity, indicating that the re-growth procedure has no serious influence on the device characteristics. A small device with a base layer hole concentration of 2.5×1019 /cm3 has a maximum oscillation frequency (f max) of 170 GHz at J C=1.7×105 A/cm2.
THE H II REGIONS OF IC 10

Deep CCD narrow-band Hα imaging of the Local Group dwarf irregular galaxy IC 10 has revealed a total of 144 H II regions. Positions, Hα luminosities, and sizes of these objects are tabulated. The Hα luminosity function has the same shape as that for more luminous galaxies. The faintest H II regions are at the low-luminosity end of the generally observed luminosity function for H II regions in galaxies, with fluxes of only, ~1035^ erg sec-1^. The size distribution has an exponential shape, as for other galaxies, with a size scale of 23 pc. The morphologies of different H II regions are discussed and compared to those in other galaxies. Published radio continuum and CO maps compare well with the Hα emission distribution in the brightest areas, when smoothed to comparable resolution. The distribution of H I is roughly similar in the central areas to the H II but is much more widely distributed in the outer areas.
Galaxy groups at 0.3 ≤z≤ 0.55 – II. Evolution to z~ 0

We compare deep Magellan spectroscopy of 26 groups at 0.3 ≤ z ≤ 0.55, selected from the Canadian Network for Observational Cosmology 2 field survey, with a large sample of nearby groups from the 2PIGG catalogue. We find that the fraction of group galaxies with significant [OII]λ3727 emission (≥5 A) increases strongly with redshift, from ∼29 per cent in 2dFGRS to ∼58 per cent in CNOC2, for all galaxies brighter than ∼M* + 1.75. This trend is parallel to the evolution of field galaxies, where the equivalent fraction of emission-line galaxies increases from ∼53 to ∼75 per cent. The fraction of emission-line galaxies in groups is lower than in the field, across the full redshift range, indicating that the history of star formation in groups is influenced by their environment. We show that the evolution required to explain the data is inconsistent with a quiescent model of galaxy evolution; instead, discrete events in which galaxies cease forming stars (truncation events) are required. We constrain the probability of truncation (P trunc ) and find that a high value is required in a simple evolutionary scenario neglecting galaxy mergers (P trunc ≥ 0.3 Gyr -1 ). However, without assuming significant density evolution, P trunc is not required to be larger in groups than in the field, suggesting that the environmental dependence of star formation was embedded at redshifts z ≥ 0.45.
The evolution of solar ultraviolet luminosity

In view of the major role of the sun in defining the properties of planetary atmospheres, their evolution cannot be fully understood outside the context of an evolving sun. The ultraviolet radiation is especially interesting because of its strong interaction with planetary atmospheres. We use astronomical observations of stars that are analogous to the sun in order to reconstruct a tentative account of the evolution of solar UV luminosity. A wealth of evidence indicates that the young sun was a much more powerful source of energetic particles and radiation than it is today. While on the main sequence, solar activity has declined as an inverse power law of age (between t−5 and t−1.2) as a consequence of angular momentum loss to the solar wind. Recent IUE satellite observations of premain sequence stars suggest that before the sun reached the main sequence (at an age of about 50 m.y.), it may have emitted as much as 104 times as much ultraviolet radiation (λ < 2000 A) than it does today. These results could impact our understanding of the photochemistry and escape of constituents of primordial planetary atmospheres.
Evaluation of petroleum generation by hydrous phrolysis experimentation

Generation and expulsion of oil from organic sedimentary rocks have been achieved in the laboratory by a technique known as hydrous pyrolysis. This technique maintains a liquid water phase in contact with organic sedimentary rocks during their heating at subcritical water temperatures (less than 374 °C ). The expelled oil accumulates on the water surface and contains no measurable olefmic hydrocarbons. Hydrous pyrolysis provides a means of acquiring inform ation relating to stages, kinetics an d indices of petroleum generation that would be difficult to obtain from a study of only the natural system
Experimental and numerical investigation of a shock wave impingement on a cylinder

This paper presents an experimental study and a numerical simulation of the impingement of an oblique shock wave on a cylinder. The investigation was undertaken to attain two goals. The first goal was to experimentally investigate and document the complex three-dimensional shock wave and boundary-layer interaction occurring in practical problems, such as the shock-wave impingement from the Shuttle nose on an external fuel tank, and store interference on a supersonic tactical aircraft. The second goal was to carry out a comparison of experimental measurements and numerical computations of such complex flows. The experimental results revealed a complex flowfield with two separation zones, regions of cross flow, reflected shocks, and expansion fans. The numerical predictions agreed surprisingly well with the measured results, both on the surface and in the flowfield. However, some important flow details, such as the size and extent of the separation, and the reflected shock-wave system, were not predicted.
Mach wave emission from a high-temperature supersonic jet

Solutions to the compressible Rayleigh equation reveal the existence of several families of supersonically convecting instability waves. These waves directly radiate noise to the jet far field. The predicted noise characteristics are compared to previously acquired experimental data for an axisymmetric Mach 2 fully pressure balanced jet (i.e., P e /P a =1.0) operating over a range of jet total temperatures from ambient to 1370 K. The results of this comparison show that the first-order supersonic instability wave and the Kelvin-Helmholtz first-, second-, and third-order modes have directional radiation characteristics that are in agreement with observed data. The assumption of equal initial amplitudes for all of the waves leads to the conclusion that the flapping mode of instability dominates the noise radiation process of supersonic jets. At a jet temperature of 1370 K, supersonic instability waves are predicted to dominate the noise radiated at high frequency at narrow angles to the jet axis
The Integrated Density of States for Some Random Operators with Nonsign Definite Potentials

We study the integrated density of states of random Anderson-type additive and multiplicative perturbations of deterministic background operators for which the single-site potential does not have a fixed sign. Our main result states that, under a suitable assumption on the regularity of the random variables, the integrated density of states of such random operators is locally Holder continuous at energies below the bottom of the essential spectrum of the background operator for any nonzero disorder, and at energies in the unperturbed spectral gaps, provided the randomness is sufficiently small. The result is based on a proof of a Wegner estimate with the correct volume dependence. The proof relies upon the Lp-theory of the spectral shift function for p⩾1 (Comm. Math. Phys.218 (2001), 113–130), and the vector field methods of Klopp (Comm. Math. Phys.167 (1995), 553–569). We discuss the application of this result to Schrodinger operators with random magnetic fields and to band-edge localization.
Neutron-proton effective range parameters and zero- energy shape dependence

A completely model-independent effective range theory fit to available, unpolarized, np scattering data below 3 MeV determines the zero-energy free proton cross section {sigma}{sub 0} = 20.4287 {+-} 0.0078 b, the singlet apparent effective range r{sub s} = 2.754 {+-} 0.018{sub stat} {+-} 0.056{sub syst} fm, and improves the error slightly on the parahydrogen coherent scattering length, a{sub c} = -3.7406 {+-} 0.0010 fm. The triplet and singlet scattering lengths and the triplet mixed effective range are calculated to be a{sub t} = 5.4114 {+-} 0.0015 fm, a{sub s} = -23.7153 {+-} 0.0043 fm, and {rho}{sub t}(0,-{epsilon}{sub t}) = 1.7468 {+-} 0.0019 fm. The model-independent analysis also determines the zero-energy effective ranges by treating them as separate fit parameters without the constraint from the deuteron binding energy {epsilon}{sub t}. These are determined to be {rho}{sub t}(0,0) = 1.705 {+-} 0.023 fm and {rho}{sub s}(0,0) = 2.665 {+-} 0.056 fm. This determination of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is most sensitive to the sparse data between about 20 and 600 keV, where the correlation between the determined values of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is at a minimum. This correlation is responsible for the large systematic error in r{sub s}. Moremore » precise data in this range are needed. The present data do not event determine (with confidence) that {rho}{sub t}(0,0) {ne} {rho}{sub t}(0, -{epsilon}{sub t}), referred to here as ''zero-energy shape dependence''. The widely used measurement of {sigma}{sub 0} = 20.491 {+-} 0.014 b from W. Dilg, Phys. Rev. C 11, 103 (1975), is argued to be in error. « less
Modeling of distributed feedback semiconductor lasers with axially-varying parameters

A numerical model that is capable of predicting important laser characteristics such as the threshold gain and the gain margin between the main and side modes for a distributed-feedback (DFB) semiconductor laser of arbitrary complexity is described. The method consists of solving the coupled-mode equations with axially varying parameters iteratively until the boundary conditions at the two facets are satisfied. The numerical model is applied to two DFB laser structures. In the case of a multiple-phase-shift DFB laser the results show that such devices can have a more uniform axial distribution than that of a conventional quarter-wave-shifted DFB laser while maintaining sufficient gain margin between the main and side modes. In the case of a dual-pitch DFB laser it is shown that the incorporation of a slightly different grating period ( approximately 0.1%) over a small section can provide a gain margin that is comparable to that achieved in quarter-wave-shifted DFB lasers. >
THE DUST BUDGET OF THE SMALL MAGELLANIC CLOUD: ARE ASYMPTOTIC GIANT BRANCH STARS THE PRIMARY DUST SOURCE AT LOW METALLICITY?

We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud, using the 8 μm excess emission as a proxy for the dust-production rate (DPR). We find that asymptotic giant branch (AGB) and red supergiant (RSG) stars produce (8.6–9.5) × 10−7 M☉ yr−1 of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%–50% uncertainty in individual DPRs). RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called extreme AGB stars) account for 87%–89% of the total dust input from cool evolved stars. We also estimate the dust input from hot stars and supernovae (SNe), and find that if SNe produce 10−3 M☉ of dust each, then the total SN dust input and AGB input are roughly equivalent. We consider several scenarios of SN dust production and destruction and find that the interstellar medium (ISM) dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. We find that AGB stars contribute only 2.1% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggests that dust must grow in the ISM or be formed by another unknown mechanism.
Strong-field dynamics of a multimode, standing-wave dye laser

A set of strong-field Maxwell–Bloch equations is derived for a multimode, standing-wave, homogeneously broadened laser such as a dye laser, which obeys the atomic rate-equation limit. Numerical solutions show that the energy in the cavity oscillates between the field and the gain medium at multiples of the cavity mode spacing. By using these Maxwell–Bloch equations, intensity autocorrelation functions of a dye-laser system under varying conditions are calculated. We find that the numerical results qualitatively agree with recent experimental data.
The structure of the heliospheric current sheet: 1978–1982

The structure of the heliospheric magnetic field changes substantially during the 11 year sunspot cycle. Its configuration for the period 1976 through 1982 using a potential field model was calculated. The structure during the rising phase, maximum, and early decline of sunspot cycle 21, from 1978 to 1982 is considered.
Modeling of a light elastic beam by a system of rigid bodies

This paper has shown that a light elastic beam, in the case of small elastic deformations, can be modeled by a kinematic chain without branching composed of rigid bodies which are connected by passive revolute or prismatic joints with corresponding springs in them. Elastic properties of the beam are modeled by the springs introduced. The potential energy of the elastic beam is expressed as a function of components of the vector of elastic displacement and the vector of elastic rotation calculated for the elastic centre of the beam, which results in the diagonal stiffness matrix of the beam. As the potential energy of the introduced system of bodies with springs is expressed in the function of relative joint displacements, the diagonal stiffness matrix is obtained. In addition, these two stiffness matrices are equal. The modeling process has been demonstrated on the example of an elastic beam rotating about a fixed vertical axis, with a rigid body whose mass is considerably larger than the beam mass fixed to its free end. Differential equations of motion have been formed for this mechanical system. The modeling technique described here aims at expanding of usage of well developed methods of dynamics of systems of rigid bodies to the analysis of systems with elastic bodies.
The Narrow-Line Region of Seyfert Galaxies: Narrow-Line Seyfert 1 Galaxies versus Broad-Line Seyfert 1 Galaxies

It is known that the spectral energy distribution (SED) of the nuclear radiation of narrow-line Seyfert 1 galaxies (NLS1's) has different shapes with respect to that of ordinary broad-line Seyfert 1 galaxies (BLS1's) particularly in X-ray wavelengths. This may cause some differences in the ionization degree and the temperature of gas in narrow-line regions (NLRs) between NLS1's and BLS1's This paper aims to examine whether or not there are such differences in the physical conditions of NLR gas between them. For this purpose, we have compiled the emission-line ratios of 36 NLS1's and 83 BLS1's from the literature. Comparing these two samples, we have found that the line ratios of [O I] λ6300/[O III] λ5007 and [O III] λ4363/[O III] λ5007, which represent the ionization degree and the gas temperature respectively, are statistically indistinguishable between NLS1's and BLS1's. Based on new photoionization model calculations, we show that these results are not inconsistent with the difference of the SED between them. The influence of the difference of SEDs on the highly ionized emission lines is also briefly discussed.
Interferometric measurements of electric field-induced displacements in piezoelectric thin films

Interferometric measurements of electric field‐induced displacements in piezoelectric thin films using single‐beam and double‐beam optical detection schemes are reported. It is shown that vibrational response measured with a single‐beam interferometer includes a large contribution of the bending motion of substrate. Therefore, it is difficult to apply single‐beam technique for piezoelectric measurements in thin films. To suppress the bending effect a high‐resolution double‐beam interferometer is proposed. The sensitivity of the interferometer is significantly improved in comparison with previously reported system. The interferometer is shown to resolve small displacements without using a lock‐in technique. An example of the interferometric capabilities is demonstrated with experimental results on electric field, frequency, and time dependences of piezoelectric response for quartz and Pb(Zr,Ti)O3 thin film.
Comet Giacobini-Zinner - A normal comet?

Observations of Comet Giacobini-Zinner were obtained during its 1985 apparition using an IDS spectrograph at McDonald Observatory. Column densities and production rates were computed. The production rates were compared to observations of other normal comets. Giacobini-Zinner is shown to be depleted in C2 and C3 relative to CN. These production rates are down by a factor of 5. 12 references.
Microfocusing VLS-grating-based beamline for advanced microscopy

A beamline combining the highest possible photon density on the sample with medium energy resolving power is under construction at the third generation storage ring ELETTRA in Trieste. It is designed to meet the requirements for the best instrumental performance of two imaging microscopes, which are going to be used for surface science research and micro- characterization of magnetic materials. The high photon density on the sample will be preserved within a rather wide photon energy range, between 20 to 1000 eV. In order to meet these requirements, building a simple while economical beamline we use a Variable Line Space (VLS) grating solution for the monochromator and adaptive plane elliptical mirrors for the re-focusing. In particular two low groove density VLS plane gratings (made by Jobin-Yvon) will cover the energy range between 20 and 1000 eV and a spherical grating will cover the lower energy (less than 20 eV) and focus the zero order light, still in grazing incidence mode. Before the monochromator, an internally cooled toroidal mirror (developed at ELETTRA) will pre-focus the radiation in different positions for the sagittal and tangential directions. After the exit slit, two different branches will host two couples of adaptive plane elliptical mirrors (developed in collaboration with S.E.S.O.) mounted in a Kirkpatrick-Baez configuration. The minimum final spot size will be of the order of 4 micrometer2 with a maximum photon density of the order of 1014 ph/sec/micrometer2. The advantage of the selected solutions and the overall expected performance will be described in detail.