The Galilei group involves mass as a central charge. We show that the associated superselection rule is incompatible with the observed phenomenology of superfluid helium 4: this is recovered only under the assumption that mass is spontaneously broken. This remark is somewhat immaterial for the real world, where the correct space-time symmetries are encoded by the Poincaré group, which has no ce...

A popular question in recreational mathematics is the following: If we drop a spaghetti noodle and it breaks at two random places, what is the probability that we can form a triangle with the three resulting segments? See for example [2, chap.1, sec.6], [3, p.6], [4, p.31], or [7, p.30-36]. This is an elementary problem in geometric probability. Clearly the length of the noodle (or equivalently...

Introduction: Pallasites are widely considered to be poor in sulphide, as such little is known about troilite evolution and processing. Very few examples exist indicating the multiple stages of troilite evolution. Discussed here are two such samples of FeS structures one is a nickel enriched FeS grain in the main group pallasite Hambleton. The other is a series of micron FeS particles within ol...

In general, a physical system consists of a finite or infinite number of degrees of freedom which may or may not interact. The dynamics is prescribed by a set of evolution equations which follow from varying the action with respect to the different degrees of freedom. A symmetry then corresponds to a group of transformations on the space time coordinates and/or the degrees of freedom that leave...

We present and discuss the properties and the main results of a cosmological model with a spontaneously-broken chiral symmetry. The model contains and relates dynamically, two spin-zero fields. The scalar field can provide the dynamical basis for inflation in the early universe. The pseudoscalar, Goldstone field can provide an early, small residual vacuum energy density, the absolute value of w...

Given a matroid M represented by a linear subspace L ⊂ C (equivalently by an arrangement of n hyperplanes in L), we define a graded ring R(L) which degenerates to the Stanley-Reisner ring of the broken circuit complex for any choice of ordering of the ground set. In particular, R(L) is Cohen-Macaulay, and may be used to compute the h-vector of the broken circuit complex of M . We give a geometr...

Abstract RE 2 SiO 5 ( = Yb and Lu) are significant environmental barrier coating (EBC) materials, in which surface oxygen vacancy play crucial roles their structural stability functionality. In this work, the configuration thermodynamics of (1 0 0), (0 1 1) surfaces investigated by first‐principles calculations. The is preferred energetically, attributed to weak bond broken environment large ra...