Stability of equilibria of a two-phase Stokes-osmosis problem

Within the framework of variational modelling we derive a two-phase moving boundary problem that describes the motion of a semipermeable membrane separating two viscous liquids in a fixed container. The model includes the effects of osmotic pressure and surface tension of the membrane. For this problem we prove that the manifold of steady states is locally exponentially attractive. © European Mathematical Society 2016

Connecting core-collapse supernova remnants and their central neutron stars

The topic of this thesis is the investigation of core-collapse supernova remnants and their central neutron stars, with an emphasis on the intrinsic connection between the two. This is achieved via spectroscopic and astrometric analysis of their X-ray emission, which is characteristic for the hot plasma and energetic nonthermal processes occurring in these objects. On one hand, this work investigates the velocity distribution of central compact objects (CCOs), a class of neutron stars characterized by purely thermal emission. Via careful astrometric calibration of data from the Chandra X-ray telescope, it is shown that none of the investigated CCOs exhibits a problematically high velocity in the celestial plane, which would exceed the expectation for the recoil experienced by the neutron star during the explosion. Furthermore, the presented proper motion measurements are used, in combination with the expansion of the associated supernova remnants (SNRs), to constrain their ages in a model-independent manner. This allows dating the SNR Puppis A to an age of 4600 +/- 700 years, and establishing strict upper limits on the ages of the SNRs G350.1-0.3 and RX J1713.7-3946, at 700 and 1700 years, respectively. This is complimented by spectroscopic analysis of the X-ray emission of the SNRs Puppis A and Vela with physically motivated models, using data from the recently launched SRG/eROSITA telescope. In Puppis A, this allows for the identification of regions which were only recently shock-heated, as well as a detailed search for ejecta produced during the explosion. This reveals that Puppis A contains an atypically high fraction of silicon for a core-collapse SNR, as well as a misalignment of intermediate-mass elements with the recoil direction implied by the motion of the neutron star. Similarly, in the much older Vela SNR, an unexpected composition of X-ray detected ejecta is revealed, with strongly supersolar abundance ratios of neon and magnesium compared to oxygen. Furthermore, the presented analysis for the first time allows for isolating the hard synchrotron emission of the central Vela pulsar wind nebula from the softer thermal emission from the SNR. This effort demonstrates a much larger extent of the synchrotron nebula than visible at other wavelengths, at a radius up to three degrees. A possible explanation for its phenomenology is the slow diffusion of high-energy electrons through a relatively weak ambient magnetic field, similarly to the gamma-ray halos observed around several older pulsars

Man's creation and salvation according to George V. Florovsky

The task of the thesis is to systematize the doctrine of the creation and the salvation of man as presented in the essays of one of the most important Orthodox theologians: George V. Florovsky (1893 - 1979).The doctrine of creation is the presupposition for Plorovsky's whole theology, for it lays down the basics . and foundations of all other doctrines. Creation implies (first of all) the categories of space and time for created beings in distinction with the divine mode of existence. These two different modes of existence imply, on the one hand, the reality of creaturely freedom and Its consequences (the Fall, sin, evil and freedom of choice), and on the other, the divine freedom to create, which for Plorovsky necessitates the distinction in God between the divine being and the divine energies. While the first part of the doctrine of creation is concerned with the distinguishing principle between God and man, i.e. 'nature', the second part deals with the personal aspect of this relationship, which is the doctrine of theosis. The doctrine of the salvation of man is constructed in the same way as the doctrine of creation, i.e. according to the distinction between nature and person. Thus, Christology is concerned with the healing of human nature, which Is ultimately the abolition of mortality. Ecclesiology is the doctrine concerning the salvation of the human person. Being the body of Christ, the church is the realm for this salvation, for it is the church which offers the divine means of salvation, the sacraments of baptism and the Eucharist. In conclusion, a critical assessment of Plorovsky's doctrine considers his fundamental distinction between nature and person from a Lutheran perspective

Historical Burdens on Physics

When learning physics, one follows a track very similar to the historical path of the evolution of this science: one takes detours, overcomes superfluous obstacles and repeats mistakes, one learns inappropriate concepts and uses outdated methods. In the book, more than 200 articles present and analyze such obsolete concepts methods. All articles have the same structure: 1. subject, 2. deficiencies, 3. origin, 4. disposal. The articles had originally appeared as columns in various magazines. Accordingly, we had tried to write them in an easily understandable way

Well-posedness for a moving boundary model of an evaporation front in a porous medium

We consider a two-phase elliptic–parabolic moving boundary problem modelling an evaporation front in a porous medium. Our main result is a proof of short-time existence and uniqueness of strong solutions to the corresponding nonlinear evolution problem in an Lp-setting. It relies critically on nonstandard optimal regularity results for a linear elliptic–parabolic system with dynamic boundary condition.</p

Differensskriftet

Slagmark præsenterer hermed Hegels Differens-skrift fra 1801 der blandt andet indeholder en række refleksioner over de grundlæggende spørgsmål vedrørende frembringelsen af en filosofi om det absolutte, om forholdet mellem filosofisk tænkning og systemambition og medrefleksionen af de historiske betingelser hvorunder tænkningen må udfolde sig; skriftet er forsynet med en instruktiv indledning af Sune Frølund, der også har oversat originalteksten

Phantastes Chapter 2: Heinrich von Ofterdingen

Novalis is Georg Philipp Friedrich Freiherr von Hardenberg (1772-1801). A German writer who helped define German Romanticism, he was a key influence on MacDonald. Heinrich von Ofterdingen (1802) is a fantastical romance that concerns a young poet in search of love, who has dream visions. A central symbol in the work is a blue flower, which has become an icon for German Romanticism