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

Us and them : the image of the others in the Swedish-American periodicals for youth (1890-1920)

Between 1890 and 19201 Swedish immigrants to America established a well-organized and dynamically working ethnic community. With the increase in their number and the development of ethnic institutions, the question of ethnic identity emerged. It became especially pressing when immigrants’ children started growing up and looking for their own, unique space - both within their ethnic group and American society. Ethnic leaders attempted to respond to this situation with creating an ideology which would correspond with the complex cultural background of young generations. Ethnic press and literature were of crucial importance in this process. The literary leaders strove to present what it meant to be Swedish-American, but also - what it did not mean. The latter was easiest to explain through the useful category of Others. Thus, the focus of this chapter is the image of the Others as presented in the Swedish-American writings for youth. Drawing on the material published by the Lutheran publishing house Augustana Book Concern within the years 1890 - 1920, it examines the stereotypes, values and features attributed to Them, as contrasted to Us, ‘real’ Swedish-Americans. Since Augustana leaders made Lutheranism the very core of their message, the Others will be analyzed within the context of religion

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

Interpreting Ulysses data using inverse scattering theory: Oblique Alfv\'en waves

Solitary wave structures observed by the Ulysses spacecraft in the solar wind were analyzed using both inverse scattering theory as well as direct numerical integration of the derivative nonlinear Schr\"odinger (DNLS) equation. Several of these structures were found to be consistent with soliton solutions of the DNLS equation. Such solitary structures have been commonly observed in the space plasma environment and may, in fact, be long-lived solitons. While the generation of these solitons may be due to an instability mechanism, e.g., the mirror instability, they may be observable far from the source region due to their coherent nature.Comment: 20 pages, 3 figures, accepted by Journal of Geophysical Research: Space Physics; typographical errors fixe

Vanadium, niobium and tantalum by XPS

We present high-resolution XPS spectra of elemental vanadium, niobium and tantalum sputter-cleaned by Ar^+ ions. The energy scales are shown without applying any corrections, and the position of the Fermi level was verified to be at zero binding energy within better than 0.1 eV, as determined from the Fermi edge measurement

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

The value in creating craft:Considering the why of handwork

The standard economic approach to craft would value craft based on market price and focus on traditional economic metrics like supply and demand. Many crafts researchers focus on the commercialization of handmade goods and their decline as technology produces similar products. The cultural economic perspective can take into account more than simply the market value of an object produced by a craftsperson, and can look at the importance of a crafts culture and the act of creating crafts for the individuals who create these goods. This research considers the current spaces in which craft is discussed and defined (academically and by consumers) and looks at the value of craft labor outside of standard economic considerations. In a grounded theory study, craftspeople speak for themselves about why they value their work, what craftwork contributes to society, and how their craft practice helps them realize values