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The purpose of this paper is to explore a resolution for the Faint Young Sun Paradox that has been mostly rejected by the community, namely the possibility of a somewhat more massive young Sun with a large mass loss rate sustained for two to three billion years. This would make the young Sun bright enough to keep both the terrestrial and Martian oceans from freezing, and thus resolve the paradox. It is found that a large and sustained mass loss is consistent with the well observed spin-down rate of Sun-like stars, and indeed may be required for it. It is concluded that a more massive young Sun must be considered a plausible hypothesis.
Fletcher & Martens have successfully modeled solar hard X-ray sources observed at the top and footpoints of flaring magnetic loops with a Fokker-Planck type particle transport code. I show here that there are invariances in the Fokker-Planck equations that make these results applicable to environments with vastly different physical parameters, such as hard X-ray flares in accretion disks in active galactic nuclei, and in RS CVn and ALGOL type binaries.
The Sun’s activity has been evolving in the ascending phase of Solar Cycle 23 since 1996. Similarly, the research on solar activity is also in the ascending phase of a new active period. Numerous new results have been obtained from a large amount of space and ground observations covering a wide spectral range. In particular, observations with YOHKOH, SOHO, and TRACE have revealed a multitude of phenomena and processes in the solar atmosphere which provide us a new picture of the Sun.
During the September 1996 campaign of multi-wavelength observations with the SOHO (SUMER, CDS, EIT, MDI, LASCO) and Yohkoh (SXT) spacecraft, the HAO Mauna Loa Solar Observatory Chromospheric Helium Imaging Photometer and the Nobeyama radioheliograph, a filament disparition brusque (DB) associated with a Coronal Mass Ejection (CME) was observed. The timeline of this complex event, which lasted for tens of hours, shows that the CME had started before the DB of a filament, while the main “bubble” of the CME was probably launched hours after the DB from the so-called “zipper” region. All these suggest that a general reorganization of large-scale fields was taking place on the Sun, and both the DB and the CME were symptoms of this.
Vestibular nerve section is a highly effective procedure for the control of vertigo in patients with Ménière's disease. However, hearing loss is a possible complication. If hearing loss occurs after vestibular nerve section, magnetic resonance imaging should make it possible to establish the presence or absence of an intact cochlear nerve.
Case report and review of the world literature concerning cochlear implantation after vestibular nerve section.
We present a patient who developed subtotal hearing loss after vestibular nerve section. Magnetic resonance imaging was used to verify the presence of an intact cochlear nerve, enabling successful cochlear implantation.
To our knowledge, this is the first reported case of cochlear implantation carried out after selective vestibular nerve section. Given recent advances in cochlear implantation, this case indicates that it is essential to make every effort to spare the cochlear nerve if vestibular nerve section is required. If hearing loss occurs after vestibular nerve section, magnetic resonance imaging should be undertaken to establish whether the cochlear nerve is intact.
The ternary transition metal nitrides of general formulation AMN2 (A = alkaline earth metal, M = transition metal) have been systematically studied. These compounds have been synthesised by high temperature solid state reaction from their component binary nitrides in sealed systems. The structures of these materials have been determined by powder X-ray diffraction (PXD) and two layered structure-types (α-NaFeO2-type and KCoO2-type) have been observed, thus far. Intriguingly, magnetic measurements performed on nitride samples indicate they may not be diamagnetic (d = 0, S = 0) as their nominal stoichiometry suggests.
The period doubling renormalization operator was introduced by Feigenbaum and by Coullet and Tresser in the 1970s to study the asymptotic small-scale geometry of the attractor of one-dimensional systems that are at the transition from simple to chaotic dynamics. This geometry turns out not to depend on the choice of the map under rather mild smoothness conditions. The existence of a unique renormalization fixed point that is also hyperbolic among generic smooth-enough maps plays a crucial role in the corresponding renormalization theory. The uniqueness and hyperbolicity of the renormalization fixed point were first shown in the holomorphic context, by means that generalize to other renormalization operators. It was then proved that, in the space of C2+α unimodal maps, for α>0, the period doubling renormalization fixed point is hyperbolic as well. In this paper we study what happens when one approaches from below the minimal smoothness thresholds for the uniqueness and for the hyperbolicity of the period doubling renormalization generic fixed point. Indeed, our main result states that in the space of C2 unimodal maps the analytic fixed point is not hyperbolic and that the same remains true when adding enough smoothness to get a priori bounds. In this smoother class, called C2+∣⋅∣, the failure of hyperbolicity is tamer than in C2. Things get much worse with just a bit less smoothness than C2, as then even the uniqueness is lost and other asymptotic behavior becomes possible. We show that the period doubling renormalization operator acting on the space of C1+Lip unimodal maps has infinite topological entropy.