Normal and almost normal surfaces are essential tools for algorithmic 3-manifold topology, but to use them requires exponentially slow enumeration algorithms in a high-dimensional vector space. The quadrilateral coordinates of Tollefson alleviate this problem considerably for normal surfaces, by reducing the dimension of this vector space from 7n to 3n (where n is the complexity of the underlyi...

Nuclear pore complexes (NPCs) prepared from Xenopus laevis oocyte nuclear envelopes were studied in "intact" form (i.e., unexposed to detergent) and after detergent treatment by a combination of conventional transmission electron microscopy (CTEM) and quantitative scanning transmission electron microscopy (STEM). In correlation-averaged CTEM pictures of negatively stained intact NPCs and of dis...

We report on the first implementation of a single-photon avalanche diode (SPAD) in 90nm complementary metal oxide semiconductor (CMOS) technology. The detector features an octagonal multiplication region and a guard ring to prevent premature edge breakdown using a standard mask set exclusively. The proposed structure emerged from a systematic study aimed at miniaturization, while optimizing ove...

in this note we introduce the notion of weak mccoy rings as a generalization of mccoy rings, and investigate their properties. also we show that, if is a semi-commutative ring, then is weak mccoy if and only if is weak mccoy.

We study central extensions of division rings with orderings of higher level. We show that orderings extend to certain immediate and inert extensions. Further, it is proved that any n–ordered division ring can be extended to a n–ordered division ring with almost real closed center. In the last section an old theorem due to Neumann is generalized: every n–ordered division ring can be extended to...

Abstract Planetary rings are often speculated as being a relatively common attribute of giant planets, partly based on their prevalence within the solar system. However, formation and sustainability remain topic open discussion, most massive planet our planetary system harbors very modest ring Here, we present results an N -body simulation that explores dynamical constraints presence substantia...