Lyons Taming

Based on Kantor's geometry, we give a new Highly symmetric construction of Lyons' sporadic simple group $Ly$ via its minimal representation over $\mathbb F_5^{111}$, thus obtaining elementary existence proofs for both the group and the representation at one stroke.Comment: 42 page

Cometary Astropause of Mira Revealed in the Far-Infrared

Evolved mass-losing stars such as Mira enrich the interstellar medium (ISM) significantly by their dust-rich molecular wind. When these stars move fast enough relative to the ISM, the interaction between the wind and ISM generates the structure known as the astropause (a stellar analog of the heliopause), which is a cometary stellar wind cavity bounded by the contact discontinuity surface between the wind and ISM. Far-infrared observations of Mira spatially resolve the structure of its astropause for the first time, distinguishing the contact surface between Mira's wind and the ISM and the termination shock due to Mira's wind colliding with the ISM. The physical size of the astropause and the estimated speed of the termination shock suggest the age of the astropause to be about 40,000 yr, confirming a theoretical prediction of the shock re-establishment time after Mira has entered the Local Bubble.Comment: 9 pages including 2 figures. To appear in the Astrophysical Journal Letter

Angularly localized Skyrmions

Quantized Skyrmions with baryon numbers $B=1,2$ and 4 are considered and angularly localized wavefunctions for them are found. By combining a few low angular momentum states, one can construct a quantum state whose spatial density is close to that of the classical Skyrmion, and has the same symmetries. For the B=1 case we find the best localized wavefunction among linear combinations of $j=1/2$ and $j=3/2$ angular momentum states. For B=2, we find that the $j=1$ ground state has toroidal symmetry and a somewhat reduced localization compared to the classical solution. For B=4, where the classical Skyrmion has cubic symmetry, we construct cubically symmetric quantum states by combining the $j=0$ ground state with the lowest rotationally excited $j=4$ state. We use the rational map approximation to compare the classical and quantum baryon densities in the B=2 and B=4 cases.Comment: 22 page

Stationary field-aligned MHD flows at astropauses and in astrotails. Principles of a counterflow configuration between a stellar wind and its interstellar medium wind

A stellar wind passing through the reverse shock is deflected into the astrospheric tail and leaves the stellar system either as a sub-Alfvenic or as a super-Alfvenic tail flow. An example is our own heliosphere and its heliotail. We present an analytical method of calculating stationary, incompressible, and field-aligned plasma flows in the astrotail of a star. We present a recipe for constructing an astrosphere with the help of only a few parameters, like the inner Alfven Mach number and the outer Alfven Mach number, the magnetic field strength within and outside the stellar wind cavity, and the distribution of singular points of the magnetic field within these flows. Within the framework of a one-fluid approximation, it is possible to obtain solutions of the MHD equations for stationary flows from corresponding static MHD equilibria, by using noncanonical mappings of the canonical variables. The canonical variables are the Euler potentials of the magnetic field of magnetohydrostatic equilibria. Thus we start from static equilibria determined by the distribution of magnetic neutral points, and assume that the Alfven Mach number for the corresponding stationary equilibria is finite. The topological structure determines the geometrical structure of the interstellar gas - stellar wind interface. Additional boundary conditions like the outer magnetic field and the jump of the magnetic field across the astropause allow determination of the noncanonical transformations. This delivers the strength of the magnetic field at every point in the astrotail region beyond the reverse shock. The mathematical technique for describing such a scenario is applied to astrospheres in general, but is also relevant for the heliosphere. It shows the restrictions of the outer and the inner magnetic field strength in comparison with the corresponding Alfven Mach numbers in the case of subalfvenic flows.Comment: 19 pages, 17 figures, accepted for publication in A&

Auf den Spuren von Charlotte und Karl Bühler – Die Erschliessung der Exilbibliothek

Der Artikel stellt die Ergebnisse einer Vorstudie zur endgültigen Erschließung der Exilbibliothek von Charlotte und Karl Bühler vor. Bei einer Nachlassbibliothek wie der Exilbibliothek von Charlotte und Karl Bühler machen vor allem die Benutzungs- und Lesespuren den einmaligen Wert des Bestands aus. Demgemäß ging es in erster Linie darum, diese Exemplarspezifika zu sichern, zu erfassen und zugänglich zu machen. Da es derzeit allerdings (noch) keine einheitliche Vorgehensweise innerhalb des Österreichischen Bibliothekenverbunds bezüglich der elektronischen Verzeichnung von exemplarspezifischen Benutzungsspuren gibt, bestand die Kernaufgabe des Projekts darin, eine auf die Bedürfnisse der Bühlerschen Exilbibliothek zugeschnittene Lösung zu entwickeln

Enhancing single-cell bioconversion efficiency by harnessing nanosecond pulsed electric field processing

Nanosecond pulsed electric field (nsPEF) processing is gaining momentum as a physical means for single-cell bioconversion efficiency enhancement. The technology allows biomass yields per substrate (YX/S) to be leveraged and poses a viable option for stimulating intracellular compound production. NsPEF processing thus resonates with myriad domains spanning the pharmaceutical and medical sectors, as well as food and feed production. The exact working mechanisms underlying nsPEF-based enhancement of bioconversion efficiency, however, remain elusive, and a better understanding would be pivotal for leveraging process control to broaden the application of nsPEF and scale-up industrial implementation. To bridge this gap, the study provides the electrotechnological and metabolic fundamentals of nsPEF processing in the bio-based domain to enable a critical evaluation of pathways underlying the enhancement of single-cell bioconversion efficiency. Evidence suggests that treating cells during the rapid proliferating and thus the early to mid-exponential state of cellular growth is critical to promoting bioconversion efficiency. A combined effect of transient intracellular and sublethal stress induction and effects caused on the plasma membrane level result in an enhancement of cellular bioconversion efficiency. Congruency exists regarding the involvement of transient cytosolic Ca2+ hubs in nsPEF treatment responses, as well as that of reactive oxygen species formation culminating in the onset of cellular response pathways. A distinct assignment of single effects and their contributions to enhancing bioconversion efficiency, however, remains challenging. Current applications of nsPEF processing comprise microalgae, bacteria, and yeast biorefineries, but these endeavors are in their infancies with limitations associated with a lack of understanding of the underlying treatment mechanisms, an incomplete reporting, insufficient characterization, and control of processing parameters. The study aids in fostering the upsurge of nsPEF applications in the bio-based domain by providing a basis to gain a better understanding of cellular mechanisms underlying an nsPEF-based enhancement of cellular bioconversion efficiency and suggests best practice guidelines for nsPEF documentation for improved knowledge transfer. Better understanding and reporting of processes parameters and consequently improved process control could foster industrial-scale nsPEF realization and ultimately aid in perpetuating nsPEF applicability within the bio-based domain

Auf den Spuren von Charlotte und Karl Bühler – Die Erschliessung der Exilbibliothek

This paper presents the results of a pre-study on completing the cataloguing of the exile library of Charlotte and Karl Bühler. The value of a bequest library like the one in question lies in the unique traces of use and perusal. Consequently, the project focused on securing and indexing the specific features of the items as well as making them accessible. As there is no accorded procedure for cataloguing item-related characteristics in the Austrian Library Network (OBV) the core issue of the project was the development of a solution that fitted the specific requirements of the Bühler's bequest library

An application of the tensor virial theorem to hole + vortex + bulge systems

The tensor virial theorem for subsystems is formulated for three-component systems and further effort is devoted to a special case where the inner subsystems and the central region of the outer one are homogeneous, the last surrounded by an isothermal homeoid. The virial equations are explicitly written under additional restrictions. An application is made to hole + vortex + bulge systems, in the limit of flattened inner subsystems. Using the Faber-Jackson relation, the standard $M_{\rm H}$-$\sigma_0$ form is deduced from qualitative considerations. The projected bulge velocity dispersion to projected vortex velocity ratio, $\eta$, as a function of the fractional radius, y_{\rm BV}, and the fractional masses, $m_{\rm BH}$, and $m_{\rm VH}$, is plotted for several cases. It is shown that a fixed value of $\eta$ below the maximum corresponds to two different configurations: a compact bulge on the left and an extended bulge on the right. In addition, for fixed $m_{\rm BH}$ or $m_{\rm BV}$, and $y_{\rm BV}$, more massive bulges are related to larger $\eta$ and vice versa. The model is applied to NGC 4374 and NGC 4486, and the bulge mass is inferred and compared with results from different methods. In presence of a massive vortex $(m_{\rm VH}=5)$, the hole mass has to be reduced by a factor 2-3 with respect to the case of a massless vortex, to get the fit.Comment: 29 pages, 2 tables, and 5 figure