Fine Structure Elements Research Articles

Dynamic processes in an active region in the initial and impulsive phases of the eruptive flare event on June 7, 2011

We present the results of an analysis of Hα monochromatic and spectral observations obtained at the Crimean Astrophysical Observatory for an impressive filament eruption during a flare occurred on June 7, 2011. Our ground-based observations are combined with data acquired by multiple instruments onboard the Solar Dynamics Observatory (SDO/AIA, SDO/HMI). The evolution and dynamics of the eruptive process, the cause of eruption, the structure of the line-of-sight velocity field and fine internal structure of the eruptive filament are studied and a number of physical parameters of the eruptive filament are determined.
 The results of the analysis have shown that: 1) The evolution of the filament eruption consists of two phases: the slow-rise phase, which began about two hours before the flare onset, and the fast-rise phase, which began almost simultaneously with the flare onset. 2) The eruptive filament had a very complex internal structure and complicated line-of-sight velocity field. The filament does not erupt as a single structure. Several discrete massive absorption fragments are seen with a large number of fine-structure elements inside fragments with different velocities, as well as many plasma blobs that detach from the fragments. 3) The motion of the filament fragments is a combination of rotational motion around the axis of the fragment and a movement as a whole towards the observer. The velocities of such plasma motions are determined. 4) Hα line profiles show a large variety of contrast values, Doppler half-widths and Doppler shifts in eruptive filament elements.

Mechanical Activation of Mixtures SiO2/γ-Fe2O3 and its Impact on the Distribution of Valence Electrons

Crystalline and electronic structures of SiO2/γ-Fe2O3 mixtures have been analyzed using X-ray diffraction (XRD) and ultra-soft X-ray emission spectroscopy (USXES). The energy redistribution of Fesрd, Sisp and Op valence electrons due to changes in the mass ratio (0,2 SiO2 + 0,8 γ-Fe2O3 , 0,5 SiO2 + 0,5 γ-Fe2O3, 0,8 SiO2 + 0,2 γ-Fe2O3) of SiO2 and α-Fe2O3 in the mixtures has been studied. The FeLα, SiLα and OKα ultra-soft X-ray emission spectra of SiO2/α-Fe2O3 mixtures were compared with those of individual iron oxide and silica powders. In analyzing these bands were detected shape similarity and the presence of identical elements of fine structure in OKα and FeLα-emission spectra, it shows a high degree of hybridization and Op- Fe3d - electronic valence states. Expansion OKα and FeLα-emission bands in the low energy side is the result of additional splitting energy Op- and Fe3d - levels with increasing degree of hybridization in the mehanoaktyvatsiynoyi processing.

The relevance of otoacoustic emission fine structure

The quasi-periodic fluctuations in otoacoustic emission (OAE) amplitude and phase, known as fine structure, provide critical insight into the mechanisms of OAE generation and propagation. Whether fine structure is relevant from the perspective of hearing health remains an open question. Starting with work done under the tutelage of Professor Long, our group has conducted a decade of work investigating the clinical relevance of fine structure in general, and distortion product (DP) OAE components in particular. These studies cover a significant portion of the human lifespan (0 to ~80 yr) and the collective results provide insights into the avenues of application that hold promise. Drawing from the results of several studies conducted in our laboratory and those of collaborators and colleagues we will make the case for focused clinical application of the DPOAE components that constitute fine structure. These constituent elements appear to be ideal for monitoring of cochlear status and expose physiological changes prior to their evidence in other measures of auditory function. However, harnessing the information encapsulated in fine structure directly is not without challenge and the examination of the constituent elements of fine structure may prove more profitable for clinical applications.

Effect of preparation conditions on nanostructural features of the NAFION® type perfluorinated proton conducting membranes

Features of the fine structure of three samples of perfluorinated Nafion® type membranes—Nafion-115, its Russian analogue MF-4SK, and a new similar material PFM-E produced according to our novel water-emulsion technique—have been characterized using the small-angle neutron scattering technique. A difference in the regularity of common elements of fine structure (cylindrical channels) in the membranes has been revealed. Nafion-115 has the most regular structure with a diffraction peak corresponding to the double channel diameter and an additional broad maximum in the scattering curve indicating a long-range order in the arrangement of straight cylindrical channels. For MF-4SK, in addition, twisted and less ordered channels have been observed. In the PFM-E sample channels have a tortuous and branched structure with diameters similar to Nafion-115. Only a short-range order (40–50 A) in the arrangement of the channels has been detected, and correlation in their mutual orientation at longer distances is weakened. It has been supposed that the observed branched structure of the channels promotes an increase in water content and an improvement in proton conductivity.

The relationship between fine scale DNA structure, GC content, and functional elements in 1% of the human genome.

GC content has been shown to be an important aspect of human genomic function. Extending beyond the scope of GC content alone, there is a class of regions in the genome that have especially high GC content and are enriched for the CG dinucleotide--called CpG islands. CpG islands have been linked to biologically functional genomic elements. DNA structure also contributes to biological function. Recent studies found that some DNA structural properties are correlated with CpG island functionality. Here, we use hydroxyl radical cleavage patterns as a measure of DNA structure, to explore the relationship between GC content and fine-scale DNA structure. We show that there is a positive correlation between GC content and the solvent-accessible structural properties of a DNA sequence, and that the strength of this correlation decreases as genomic resolution increases. We demonstrate that regions of the genome that have highly solvent-accessible DNA structure tend to overlap functional genomic elements. Our results suggest that fine-scale DNA structural properties that are encoded in the genome are important for biological function, and that the highly solvent-accessible nature of high GC content regions and some CpG islands may account for some of their functional properties.

Mechanisms of near edge fine structure formation in K-edge absorption spectra of oxygen and metal atoms in the perovskite-structure titanates

Full multiple scattering in the cluster approximation with semiempirical MT potential was used for thorough investigation of the near-edge fine structure of Ti and O K spectra from PbTiO3, BaTiO3, CaTiO3 and SrTiO3 crystals. The calculated spectra were shown to be in good agreement with the experiment. The mechanisms underlying the emergence of fine structure elements of the spectra were revealed. Near-edge structure of titanium K spectra was examined in detail. In the general case, this structure was found to have five features of various nature. The quantitative description of near-edge structure requires a model of incomplete shielding of the 1s hole. Substantiation of this model was proposed.

Stokes-meter observations of the solar mean magnetic field: Probable manifestations of strong small-scale magnetic fields

For many years, information on the solar mean magnetic field (SMMF) of the Sun—an important heliophysical and astrophysical parameter—was restricted to magnetographic measurements in only one spectral line, FeI λ525.02 nm. More informative observations of the Stokes-meter parameters of the SMMF were first initiated on a regular basis at the Sayan Solar Observatory. The availability of I and V data obtained simultaneously in several spectral lines has made it possible to study fundamentally new physical problems. In this paper, based on a comparison of SMMF observations in several spectral lines, we find high correlations in the data and important systematic differences in the magnetic-field strength B, which we interpret as a manifestation of kilogauss magnetic fields in fine-structure magnetic elements. Results of theoretical modeling of the SMMF strength ratios for the FeI λ525.02 nm-FeI λ524.70 nm and FeI λ630.15 nm-FeI λ630.25 nm lines are presented. The asymmetries of the V profiles of four lines near the FeI λ525.02 nm line are examined; these lines are important diagnostics for studies of small-scale dynamical processes. The Sayan Solar Observatory SMMF measurements are in good consistency with the Wilcox Solar Observatory data for 2003: for a comparison of N = 137 pairs of points in the two data sets, the correlation coefficient ρ is 0.92 for the linear regression between the datasets BWSO = 0.03(±0.05) + 0.93(±0.03)BSSO.

Ab initio calculations of the electron structure of the compounds AgGaS 2, CdGa 2S 4, InPS 4

Crystalline structures of the compounds in the row AgGaS 2–CdGa 2S 4–InPS 4 originate from the sphalerite structure with the gradual growth of the deficiency of metallic atoms from defect-free Ag 4 IGa 4 IIIS 8 to □ 2 IICd 2 IIGa 4 IIIS 8 and further to □ 2 IIIIn 2 III□ 2 VP 2 VS 8, where the symbol □ denotes a pseudovacancy. With the FEFF8 full multiple-scattering code, the local partial electron densities states of all atoms of all compounds investigated have been calculated. A comparison of the calculated electron densities with the experimental X-ray K- and L 2,3-spectra of emission and absorption of sulfur and phosphorus shows good correspondence between the form and energy positions of the fine structure elements. For the compounds investigated there is no significant influence of the defectiveness of the crystalline lattice on the electron density of states.

ELECTRONIC ENERGY STRUCTURE OF A SERIES OF CHALCOPYRITE-LIKE COMPOUNDS AgGaS2-CdGa2S4-InPS4

The effect of pseudovacancies on the density of electronic states of valence electrons in AgGaS2, CdGa2S4, and InPS4 is studied both experimentally, by means of X-ray spectroscopy, and theoretically, by calculating the partial densities of electronic states using the local coherent potential. The compounds under study are the derivatives of the sphalerite structural type (doubled cell) with gradually increasing deficiency of metals from \(Ag_4^I Ga_4^{III} S_8 \) to \(\square _2^{II} Cd_2^{II} Ga_4^{III} S_8 \) and further to \(\square _2^{III} In_2^{III} \square _2^V P_2^V S_8 \), where \(\square \) is a vacancy. The environment of the metal atoms remains tetrahedral, while that of the sulfur atoms changes with increasing number of vacancies from four (AgGaS2) to three (CdGa2S4) and two (InPS4). For the compounds under study, SK and PK X-ray emission and absorption spectra were recorded at a resolution of about 0.2 eV, and the local partial densities of states were calculated for all components of the compounds. The theoretical curves practically coincide in shape and energy position of fine structure elements with the corresponding experimental curves. This allowed reliable conclusions about the energy positions of electronic states at the top of the valence band and about the dependence of the SK emission and absorption spectra in the series of compounds under study on variation of the crystal structure and on the chemical composition of the nearest surroundings of sulfur atoms.

Backscattering response from periodic spatial patterns in random media

In wave-based remote sensing or radio-location of distant objects in a random medium, a high-frequency electromagnetic wave is scattered by object discontinuities, and portions of the scattered radiation can traverse the same random inhomogeneities as the initial incident field. The statistical dependence of the forward–backward travelling events results in an anomaly in the backscattered intensity pattern that carries information about the scattering object. The quality of this information depends on the ability to resolve the fine-structure elements. In this work we investigate the resolving properties of periodic spatial objects by using the random propagators of the stochastic geometrical theory of diffraction.

Interpretation of the temperature dependence ofMn2+high-field ESR spectra in the first incommensurately modulated phase of betaine calcium chloride dihydrate

By a combination of $X$-band and $Q$-band ESR investigations it was possible to distinguish between effects of first and second order in the critical behavior, which are influenced in different ways by the dynamics of the order-parameter fluctuations. The theoretical analysis is based on a Fourier expansion of the ESR fine-structure elements in terms of the harmonics of the incommensurate modulation. Second-order perturbation theory for the evaluation of the ESR spectra was applied. The splitting between the edge singularities should show a temperature dependence given by the superposition of two different critical contributions: $\ensuremath{\Delta}{B}_{\mathrm{ES}}{=a(T}_{i}\ensuremath{-}{T)}^{\overline{\ensuremath{\beta}}}{+b(T}_{i}\ensuremath{-}{T)}^{2\ensuremath{\beta}}.$ The second contribution depends on the strength of the external magnetic field. This could be clearly revealed in the comparison between $Q$- and $X$-band measurements. The influence of the Mn content ${c}_{\mathrm{Mn}}$ or of the \ensuremath{\gamma}-irradiation dose ${c}_{\ensuremath{\gamma}}$ on the splitting of the edge singularities was analyzed.

Magnetic Fields, Oscillations, and Heating in the Quiet Sun Temperature Minimum Region from Ultraviolet Observations at 1600 Å

The High Resolution Telescope and Spectrograph (HRTS) instrument has obtained broadband spectroheliograph images at 1600 Å of the solar temperature minimum region. I discuss HRTS observations of quiet areas and their relation with magnetic fields, five minute oscillations, and heating. The brightness temperature of solar fine structure elements composing the supergranular network is found to be linearly proportional to the local absolute value of magnetic field strength. There is evidence for a 250-s period oscillation occurring in 10-arcsec scale patches, which however is energetically unimportant to the local heating budget. A general nonmagnetic background heating and five minute oscillations occur globally, while the network bright points occur in magnetic regions, heated perhaps from partial dissipation of Alfvén waves (whose energy flux is linearly proportional to B) in individual elemental 1500-G (at the photosphere) flux tubes which expand to form the temperature minimum fine structure bright points.

Relationship of magnetic field strength and brightness of fine-structure elements in the solar temperature minimum region

A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B.

New metric elements of the universal fine structure due to multifurcations

New universal constants are introduced which describe the fine structure of periodic windows in the chaotic region due to multifurcations defined by an arbitrary MSS-sequence. For large primary sequences the constants tend toward 2 z, where z is the order of the extremum.

Effects of strong dynamical couplings between vibrations in the IR spectra of the bifurcated hydrogen bonds

An attempt is made at explaining the nature of the mechanism of intervibrational interactions occurring in bifurcated hydrogen bonds, which are responsible for the appearance of doublet structures of the v N-H bands in infrared (IR) spectroscopy. The model employed assumes strong anharmonicity of the proton stretching vibration in the hydrogen bonds, corresponding with the three minima of the potential-energy surface. In the first order of the perturbation theory the excited state of the proton vibration can be treated as doubly degenerate. For the description of the coupling mechanism between the protonic motions and the hydrogen-bond low-frequency vibrations an approach similar to that from the “strong coupling” theory of the hydrogen-bond spectra was used. Namely, a matrix vibrational Hamiltonian of the model bifurcated hydrogen bond, describing coupling between vibrations taking place in the system, was derived. Starting from this Hamiltonian a numerical simulation of the v N-H band shapes was done for the hydrogen bond spectra. Good agreement between the calculated and the measured band shapes was achieved, along with a good reproduction of the band fine-structure elements. Nevertheless, the model failed to explain the v N-D band shapes for the deuterated analogues of the hydrogen bonds. This discrepancy is most probably connected with the relation between the proton vibration quantum magnitude and the potential-energy surface parameters.

Stimulated acceleration and confinement of deuterons in focused discharges. II

For pt.I see ibid., vol.16, no.3, p.368-73, June 1988. Methods of increasing, by a factor greater than five, the neutron yield/short Y/sub n/ from D-D fusion reactions in a plasma focus (PF) enhance both the D/sup +/-ion acceleration to energy values E/sub d/>1-8 MeV and the ion confinement in the pinch region. Nuclear activation of C and N in the (doped) filling gas of the discharge chamber and of solid targets of C and BN bombarded by the ion beam in the direction of the electrode axis (0 degrees ) confirms earlier determination of the energy spectrum of the trapped ions (d phi /sub t//dE varies as phi /sub 0t/E/sup -m/) and of the ejected beam (d phi /sub b//dE varies as phi /sub 0b/E/sub d//sup -m/, m=2.5+or-0.5 for 0.1 MeV<or approximately=E<or approximately=3 MeV). A Thomson (parabola) spectrometer with nanosecond time resolution determines the time of emission t(E) of the beam at 0 degrees . Ion acceleration and trapping occur within the small (filamentary) elements of the magnetic fine structure of the pinch, which can be dispersed on a relatively large confinement volume after the pinch disintegration. It has been found that phi /sub t// phi /sub b/>or approximately=10-10/sup 3/ for E/sub d/>or approximately=1 MeV, depending on Y/sub n/.<<ETX>>

Interpretation of oscillations in UV lines observed above sunspot umbrae

Our theory of a resonator for slow magneto-atmospheric waves in the chromosphere of a sunspot umbra has been used to check different models of the structure of the chromosphere and transition region. Oscillations of velocity and intensity in Civ, Siiv, and Oiv lines observed by Gurman et al. (1982) on the SMM spacecraft have been compared with the calculated oscillations. The observed spectrum of resonant peaks could well be explained by a gradient model of the umbral chromosphere. Different assumptions concerning the structure of the transition region do not influence the calculated resonance periods, but the amplitudes and phases of oscillations are modified. There is strong evidence for a concentration of the observed oscillations in cold fine structure elements of the transition region, even if the filling factor of such elements is very small (some few percent). Isothermal rather than adiabatic oscillations in the cold elements should be assumed in order to explain the observed fluctuations of line intensity; the relative amplitudes of pressure oscillations in the hot main component with a steep gradient of temperature are too small to explain the observed intensity fluctuations.

On the inhomogeneous structure of the chromosphere‐corona transition region above sunspot umbrae

AbstractMultiple wavelength observations of sunspot umbrae can only be expalined by an inhomogeneous, two‐component model for the structure of the umbral transition region and lower corona. The ‘Wroclaw‐Ondrejov sunspot model’ was a first step in this direction. This working model has now been improved using analytic expressions for the atmospheric structure in each component and fitting the free parameters to recent sunspot observations, particularly in EUV lines. The main component has a shallow transition region and a deep‐set corona. The second, ‘active’ component has a vast transition region in relatively cool fine structure elements embedded in the coronal main component. The spatial filling factor of this active component amounts to 5–10% in sunspots with bright EUV plumes, but is is more than ten times smaller in sunspot without such plumes. Observations with high spatial and temporal resolutions are necessary to understand in more detail the basic physical processes.

SUS 316ステンレス鋼の耐IGC, IGSCC性改良のための加工熱処理

The thermomechanical treatment aimed at the protection of the commertial type 316 stainless steel from IGC and IGSCC was investigated. This method is composed of two stepped heat treatment for aging and recrystallizing, following the fully solution treatment and heavy cold working. Optimum conditions were selected by IGC susceptibility tests, EPR and Strauss. Materials treated under the optimum condition that have the carbide dispersed fine grain structure and harmuful elements removed austenite, showed the immunity to IGC and IGSCC and the suitable phase stability. Mo which is an alloying element, playes the important role on stabilizing and dispersing of carbide through this treatment. The enhancement of the mechanical strength by this treatment is one of the advantages as compared with modification of alloying elements.

Temperature fine structure near the Sea‐ice margin of the Chukchi Sea

Temperature fine structure with peak‐to‐peak fluctuations often exceeding 2°C is prevalent throughout the marginal sea‐ice zone of the shallow Chukchi Sea in midsummer. It is normally found within 20–35 km outside of the ice and seldom farther than 5–10 km inside the ice margin. It has also been infrequently found more than 100 km south of the ice. Temperature and salinity fronts of all degrees of sharpness occur in the same general area, but the two types need not be coincident. Considerable variability in time and length scales of fine structure elements has been noted with persistences ranging from 2 hours or less to more than 20 hours and length scales ranging from 600 m to more than 20 km. While much of this variability is intrinsic, part can be accounted for by the inability to sample in the direction of flow and the relative motion between the sampling platform and fine structure element. Fine structure lenses are considerably longer parallel to the ice edge with similarity in temperature structure noted over distances of 80 and 100 km.