333 research outputs found
The Ever Changing Circumstellar Nebula Around UW Centauri
We present new images of the reflection nebula surrounding the R Coronae
Borealis Star, UW Cen. This nebula, first detected in 1990, has changed its
appearance significantly. At the estimated distance of UW Cen, this nebula is
approximately 0.6 ly in radius so the nebula cannot have physically altered in
only 8 years. Instead, the morphology of the nebula appears to change as
different parts are illuminated by light from the central star modulated by
shifting thick dust clouds near its surface. These dust clouds form and
dissipate at irregular intervals causing the well-known declines in the R
Coronae Borealis (RCB) stars. In this way, the central star acts like a
lighthouse shining through holes in the dust clouds and lighting up different
portions of the nebula. The existence of this nebula provides clues to the
evolutionary history of RCB stars possibly linking them to the Planetary
Nebulae and the final helium shell flash stars.Comment: To be published in ApJ Letters. 5 pages, 3 figures (2 in color
Method for reliable realization of a varphi Josephson junction
We propose a method to realize a Josephson junction by combining
alternating 0 and parts (sub junctions) with an intrinsically
non-sinusoidal current-phase relation (CPR). Conditions for the realization of
the ground state are analyzed. It is shown that taking into account the
non-sinusoidal CPR for a "clean junction with a ferromagnetic (F) barrier, one
can significantly enlarge the domain (regime of suitable F-layer thicknesses)
of the ground state and make the practical realization of
Josephson junctions feasible. Such junctions may also have two different stable
solutions, such as 0 and , 0 and , or and
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Meeting report: a hard look at the state of enamel research.
The Encouraging Novel Amelogenesis Models and Ex vivo cell Lines (ENAMEL) Development workshop was held on 23 June 2017 at the Bethesda headquarters of the National Institute of Dental and Craniofacial Research (NIDCR). Discussion topics included model organisms, stem cells/cell lines, and tissues/3D cell culture/organoids. Scientists from a number of disciplines, representing institutions from across the United States, gathered to discuss advances in our understanding of enamel, as well as future directions for the field
Non-language factors and language evolution
This paper is devoted to the description of the functioning and development of the language system seen in correlation with the influence of non-language factor
The effect of normal and insulating layers on 0-π transitions in Josephson junctions with a ferromagnetic barrier
Using the Usadel approach, we provide a formalism that allows us to calculate the critical current density of 21 different types of Josephson junctions (JJs) with a ferromagnetic (F) barrier and additional insulating (I) or/and normal (N) layers inserted between the F layer and superconducting (S) electrodes. In particular, we obtain that in SFS JJs, even a thin additional N layer between the S layer and F layer may noticeably change the thickness dF of the F layer at which the 0-π transitions occur. For certain values of dF, a 0-π transition can even be achieved by changing only the N layer thickness. We use our model to fit experimental data of SIFS and SINFS tunnel junctions
The effect of normal and insulating layers on 0-πtransitions in Josephson junctions with a ferromagnetic barrier
Using the Usadel approach, we provide a formalism that allows us to calculate the critical current density of 21 different types of Josephson junctions (JJs) with a ferromagnetic (F) barrier and additional insulating (I) or/and normal (N) layers inserted between the F layer and superconducting (S) electrodes. In particular, we obtain that in SFS JJs, even a thin additional N layer between the S layer and F layer may noticeably change the thickness of the F layer at which the 0-π transitions occur. For certain values of a 0-π transition can even be achieved by changing only the N layer thickness. We use our model to fit experimental data of SIFS and SINFS tunnel junctions
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