Fine-scale cavitation of ionospheric plasma caused by inertial Alfvén wave ponderomotive force

Deep, very narrow magnetic-field-aligned density depletions were observed by the Freja spacecraft during auroral oval crossings. These cavities have perpendicular width of the order of the electron skin depth c/ωpe and are associated with low-frequency electromagnetic perturbations and with discrete auroral structures. We demonstrate here that these cavities are likely produced by the ponderomotive force of inertial Alfvén waves

Multifractal structure of turbulence in the magnetospheric cusp

Magnetospheric cusps are regions which are characterized by highly turbulent plasma. We have used Polar magnetic field data to study the structure of turbulence in the cusp region. The wavelet transform modulus maxima method (WTMM) has been applied to estimate the scaling exponent of the partition function and singularity spectra. Their features are similar to those found in the nonlinear multifractal systems. We have found that the scaling exponent does not allow one to conclude which intermittency model fits the experiment better. However, the singularity spectra reveal that different models can be ascribed to turbulence observed under various IMF conditions. For northward IMF conditions the turbulence is consistent with the multifractal <i>p</i>-model of fully developed fluid turbulence. For southward IMF experimental data agree with the model of non-fully developed Kolmogorov-like fluid turbulence

Heating of the Solar Corona by Dissipative Alfven Solitons

Solar photospheric convection drives myriads of dissipative Alfven solitons (hereinafter called alfvenons) capable of accelerating electrons and ions to energies of hundreds of keV and producing the X-ray corona. Alfvenons are exact solutions of two-fluid equations for a collisionless plasma and represent natural accelerators for conversion of the electromagnetic energy flux driven by convective flows into kinetic energy of charged particles in space and astrophysical plasmas. Their properties have been experimentally verified in the magnetosphere, where they accelerate auroral electrons to tens of keV.Comment: 4 pages, 4 color figures, accepted for publication in Phys. Rev. Let

Statistical study of precipitating electrons

Energy spectra of precipitating electrons are fitted to the sum of three distributions: a power law, a Maxwellian and a Gaussian. This fitting procedure determines seven parameters which characterize the essential features of each spectrum. These characteristic parameters are used to carry out various studies involving precipitating electrons. It is shown that the absence of the power-law population from a particular spectrum is related to the softness of the precipitating primary flux, that the Maxwellian temperature and the Gaussian peak energy have a positive correlation the strength of which varies with local time, that the upward moving Gaussian population has a loss cone distribution, and that the one dimensional velocity distribution parallel to the magnetic field occasionally displays a plateau or a hump on the tail

Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem

The impulsive phase of a solar flare marks the epoch of rapid conversion of energy stored in the pre-flare coronal magnetic field. Hard X-ray observations imply that a substantial fraction of flare energy released during the impulsive phase is converted to the kinetic energy of mildly relativistic electrons (10-100 keV). The liberation of the magnetic free energy can occur as the coronal magnetic field reconfigures and relaxes following reconnection. We investigate a scenario in which products of the reconfiguration - large-scale Alfven wave pulses - transport the energy and magnetic-field changes rapidly through the corona to the lower atmosphere. This offers two possibilities for electron acceleration. Firstly, in a coronal plasma with beta < m_e/m_p, the waves propagate as inertial Alfven waves. In the presence of strong spatial gradients, these generate field-aligned electric fields that can accelerate electrons to energies on the order of 10 keV and above, including by repeated interactions between electrons and wavefronts. Secondly, when they reflect and mode-convert in the chromosphere, a cascade to high wavenumbers may develop. This will also accelerate electrons by turbulence, in a medium with a locally high electron number density. This concept, which bridges MHD-based and particle-based views of a flare, provides an interpretation of the recently-observed rapid variations of the line-of-sight component of the photospheric magnetic field across the flare impulsive phase, and offers solutions to some perplexing flare problems, such as the flare "number problem" of finding and resupplying sufficient electrons to explain the impulsive-phase hard X-ray emission.Comment: 31 pages, 6 figure

Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

Recent efforts have demonstrated enhanced tailoring of material functionality with mixed anion materials, yet exploratory research with mixed anion chemistries is limited by the sensitivity of these materials to synthesis conditions. Synthesis of a particular metal oxynitride compound by traditional reactive annealing requires specific, limited ranges of both oxygen and nitrogen chemical potentials to establish equilibrium between the solid-state material and a reactive atmosphere. Using Ta–O–N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing (RTP) for synthesis of mixed anion inorganic materials. Heuristic optimization of reactive gas pressures to attain a desired anion stoichiometry is discussed, and the ability of RTP to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide, and oxynitride phases

Combinatorial thin film composition mapping using three dimensional deposition profiles

Many next-generation technologies are limited by material performance, leading to increased interest in the discovery of advanced materials using combinatorial synthesis, characterization, and screening. Several combinatorial synthesis techniques, such as solution based methods, advanced manufacturing, and physical vapor deposition, are currently being employed for various applications. In particular, combinatorial magnetron sputtering is a versatile technique that provides synthesis of high-quality thin film composition libraries. Spatially addressing the composition of these thin films generally requires elemental quantification measurements using techniques such as energy-dispersive X-ray spectroscopy or X-ray fluorescence spectroscopy. Since these measurements are performed ex-situ and post-deposition, they are unable to provide real-time design of experiments, a capability that is required for rapid synthesis of a specific composition library. By using three quartz crystal monitors attached to a stage with translational and rotational degrees of freedom, we measure three-dimensional deposition profiles of deposition sources whose tilt with respect to the substrate is robotically controlled. We exhibit the utility of deposition profiles and tilt control to optimize the deposition geometry for specific combinatorial synthesis experiments

Prawdopodobieństwo wystąpienia różnych patologii ciąży w rodzinach nosicieli translokacji chromosomowych wzajemnych angażujących chromosom 13

Summary Objectives: The aim of study was to estimate the probability rates for unfavorable pregnancy outcomes in carriers of reciprocal chromosomal translocations involving 13 chromosome (RCT-13q). Material and methods: We collected total empirical data about 232 pregnancies of 56 carriers coming from 28 pedigrees. RCT classification was based on classic cytogenetic methods for interpretation of breakpoint position. The probability rates of particular type of pathology related to the total number of pregnancies after ascertainment correction have been calculated with the help of Stengel-Rutkowski and Stene method. Results: The risk figures for unbalanced offspring after 2:2 disjunction and adjacent-1 segregation for the whole group of pedigrees were calculated as 5.2+/-1.7% (9/173) – medium risk, for maternal (MAT) and paternal (PAT) carriers were about 6.2+/-2.3% (7/173) and 4.8+/-3.3% (2/42) respectively. Considering different segment lengths of 13q, similar values for shorter and longer segments were obtained [4.3+/-1.9% (5/115) for 13q21→qter and 7.0+/-3.3% (4/58) for 13q12→qter]. The risk figures for miscarriages as 36.4+/-3.6% (63/173) and for stillbirths/early death as 4.6+/-31.6% (8/173) were obtained. The risk figures for unbalanced offspring after 3:1 disjunction were calculated as 7.7+/-7.45 (9/13). Conclusions: 1. Risk figures for different pregnancy outcomes are differ among particular forms of pathology 2. Probability rate for unbalanced progeny at birth was calculated as a medium risk and similar values for carriers of different segments of 13q were obtained 3. Probability rate for miscarriages was high but risk for stillbirths/early deaths of newborn was low 4. No differences in values of rate for particular forms of pathology were found for maternal and paternal carriers of RCT -13q.Streszczenie Cel pracy: Celem badań było oszacowanie prawdopodobieństwa wystąpienia różnych patologii ciąży w rodzinach nosicieli translokacji chromosomowych wzajemnych angażujących długie ramię chromosomu 13 (TCW-13q). Materiał i metody: Materiał do analizy stanowiły dane empiryczne i cytogenetyczne o 232 ciążach 56 nosicieli, uzyskane z 28 rodowodów nosicieli TCW ryzyka pojedynczego niezrównowaęenia segmentu angażujących chromosom 13. Prawdopodobieństwo wystąpienia różnych patologii ciąży oszacowano metodą Stengel-Rutkowski i Stene. Wyniki: Prawdopodobieństwo urodzenia dziecka z niezrównoważonym kariotypem w rodzinach nosicieli TCW z udziałem chromosomu 13 po segregacji 2:2 rozdziale przyległym typu 1 wynosiło 5,2+/-1,7% (9/173) – ryzyko średnie; po segregacji 3:1 ryzyko wynosiło 7,7+/-7,4% (9/13) – ryzyko średnie. W przypadku nosicielstwa matczynego (MAT) osiągnęło wartość 6,2+/-2,3% (7/173), zaś ojcowskiego (PAT) wartość 4,8+/-3,3% (2/42). Rozpatrując poszczególne segmenty chromosomu 13, prawdopodobieństwo miało następujące wartości: segment 13q21.2→qter - 4,3+/-1,9% (5/115), segment 13q12→qter – 7+/-3,3% (4/58). Ryzyko utraty ciąży na skutek ciąż obumarłych określono na 4,6+/-1,6% (8/173), natomiast ryzyko poronień samoistnych 36,4+/-3,6% (63/173). Wnioski: 1. Wielkości prawdopodobieństwa wystąpienia poszczególnych patologii ciąży w rodzinach nosicieli TCW-13q są różne. 2. Wielkość prawdopodobieństwa urodzenia dziecka z niezrównoważonym kariotypem należy do grupy ryzyka średniego; uzyskano podobne wartości w rodzinach nosicieli poszczególnych segmentów chromosomu 13. 3. Wielkość ryzyka genetycznego poronień samoistnych należy do grupy ryzyka wysokiego i jest wyższe w stosunku do ryzyka ciąż obumarłych przed terminem porodu (grupa ryzyka niskiego). 4. Nie stwierdzono różnic w wielkości wskaźników ryzyka dla poszczególnych form patologii ciąży w zależności od płci nosiciela