Origin of the Near-Ecliptic Circumsolar Dust Band

The zodiacal dust bands are bright infrared (IR) strips produced by thermal emission from circumsolar rings of particles. Two of the three principal dust bands, known as β and γ, were previously linked to the recent asteroid collisions that produced groups of fragments, so-called asteroid families, near the orbits of (832) Karin and (490) Veritas. The origin of the third, near-ecliptic α band has been unknown until now. Here we report the discovery of a recent breakup of a >20 km diameter asteroid near α's originally suspected source location in the Themis family. Numerical modeling and observations of the α-band thermal emission from the Spitzer Space Telescope indicate that the discovered breakup is the source of α-band particles. The recent formation of all principal dust bands implies a significant time variability of the circumstellar debris disks

SIMS without sums

AbstractSecondary Ion Mass Spectrometry (SIMS) is probably the most powerful analytical technique for the characterization of semiconductor materials. Its strength lies in its ability to perform high sensitivity chemical analysis directly on semiconductor materials with high spatial and depth resolution. As part of the continuing series on assessment techniques, III–Vs Review presents a mathematics-free overview of the process

Defining equations of 77-dimensional model CR hypersurfaces and models in CN\mathbb{C}^{N}

We investigate a class of CR invariants of uniformly $2$-nondegenerate CR hypersurfaces, termed modified symbols, and develop methods for deriving defining equations of CR hypersurfaces realizing different values of these invariants. For hypersurfaces in $\mathbb{C}^4$, we obtain the full classification of modified symbols realizable by weighted homogeneous (with respect to a natural weighting system) rigid CR hypersurfaces, and obtain defining equations for the recently classified $7$-dimensional homogeneous modified symbol models. Moreover, we characterize, up to CR equivalence, all weighted homogeneous rigid uniformly $2$-nondegenerate CR hypersurfaces in $\mathbb{C}^{N}$ whose holomorphic infinitesimal symmetries generate a transitive action on their Levi leaf spaces.Comment: 37 pages, comments welcomed, auxiliary Maple files include

Territorial Policy and Governance

This chapter explores evolving approaches to territorial policy and governance within the context of the European Union’s (EU) Cohesion Policy. The chapter traces evolving conceptions and models of regional policy in Europe, paying attention to the emergence of place-based and territorial approaches to promoting development and exploring the ways in which they have been manifested in reforms of the EU’s Cohesion Policy and the restructuring of sub-national policy and governance in England. The chapter addresses, in turn, the emergence of a ‘place-based’ approach to regional policy within the context of debates around whether to tailor public investments to specific places or to use similar investments across the national space; how such a place-based approach has been adopted in recent reforms to the EU Cohesion Policy; and the representation of place-based and territorial approaches to development in the context of state rescaling in England, with reference to the case of the Liverpool City Region

New examples of 22-nondegenerate real hypersurfaces in CN\mathbb{C}^N with arbitrary nilpotent symbols

We introduce a class of uniformly $2$-nondegenerate CR hypersurfaces in $\mathbb{C}^N$, for $N>3$, having a rank $1$ Levi kernel. The class includes uncountably many examples of non-equivalent structures having a given constant nilpotent CR symbol for every such symbol. Using methods that are able to handle all cases with $N>5$ simultaneously, we solve the equivalence problem for the considered structures whose symbol is represented by a single Jordan block, classify their algebras of infinitesimal symmetries, and classify the locally homogeneous structures among them. We show that the remaining considered structures, which have symbols represented by a direct sum of Jordan blocks, can be constructed from the single block structures through simple linking and extension processes

Candidates for asteroid dust trails

The contribution of different sources to the circumsolar dust cloud (known as the zodiacal cloud) can be deduced from diagnostic observations. We used the Spitzer Space Telescope to observe the diffuse thermal emission of the zodiacal cloud near the ecliptic. Several structures were identified in these observations, including previously known asteroid dust bands, which are thought to have been produced by recent asteroid collisions, and cometary trails. Interestingly, two of the detected dust trails, denoted t1 and t2 here, cannot be linked to any known comet. Trails t1 and t2 represent a much larger integrated brightness than all known cometary trails combined and may therefore be major contributors to the circumsolar dust cloud. We used our Spitzer observations to determine the orbits of these trails and were able to link them to two ("orphan" or type II) trails that were discovered by the Infrared Astronomical Satellite (IRAS) in 1983. The orbits of trails t1 and t2 that we determined by combining the Spitzer and IRAS data have semimajor axes, eccentricities, and inclinations like those of the main-belt asteroids. We therefore propose that trails t1 and t2 were produced by very recent (<~100 kyr old) collisional breakups of small, <~10 km diameter main-belt asteroids

Automated Harmonic Analysis On Common Practice Music

The following thesis reports on work performed to replicate and improve upon an algorithm for the Roman numeral harmonic analysis of homophonic choral music. Improvements made aimed to expand the reach of the algorithm, which was initially implemented specifically with Bach chorales in mind, to the broader period of common practice art music and the homophonic choral music within it. The thesis concludes by exploring potential Web-based applications for the algorithm's new implementation, with particular focus on the area of music theory education. *The associated code has been included as a supplement to this paper on the NC Docks archive