1,721,364 research outputs found
Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species
No full textTirunagaru, Krishnachaitanya, Sagadai, Manickavasagam, Kumar, Abhinav (2016): Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species. Journal of Natural History 50: 2369-2387, DOI: 10.1080/00222933.2016.1193650, URL: http://dx.doi.org/10.1080/00222933.2016.119365
Figure 4. H. varicolorus F in Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species
No full textFigure 4. H. varicolorus F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.Published as part of Tirunagaru, Krishnachaitanya, Sagadai, Manickavasagam & Kumar, Abhinav, 2016, Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species, pp. 2369-2387 in Journal of Natural History 50 on page 2381, DOI: 10.1080/00222933.2016.1193650, http://zenodo.org/record/399305
Figure 6. H. noyesi F in Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species
No full textFigure 6. H. noyesi F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.Published as part of Tirunagaru, Krishnachaitanya, Sagadai, Manickavasagam & Kumar, Abhinav, 2016, Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species, pp. 2369-2387 in Journal of Natural History 50 on page 2385, DOI: 10.1080/00222933.2016.1193650, http://zenodo.org/record/399305
Elliptic Fibrations on a Generic Jacobian Kummer Surface
Full text linkWe describe all the elliptic fibrations with section on the Kummer surface X of the Jacobian of a very general curve C of genus 2 over an algebraically closed field of characteristic 0, modulo the automorphism group of X and the symmetric group on the Weierstrass points of C. In particular, we compute elliptic parameters and Weierstrass equations for the 25 different fibrations and analyze the reducible fibers and Mordell-Weil lattices. This answers completely a question posed by Kuwata and Shioda in 2008.National Science Foundation (U.S.) (Grant DMS-0757765)National Science Foundation (U.S.) (Grant DMS-0952486)Solomon Buchsbaum AT&T Research Fun
Multiplicative excellent families of elliptic surfaces of type E[subscript 7] or E[subscript 8]
No full textWe describe explicit multiplicative excellent families of rational elliptic surfaces with Galois group isomorphic to the Weyl group of the root lattices E[subscript 7] or E[subscript 8]. The Weierstrass coefficients of each family are related by an invertible polynomial transformation to the generators of the multiplicative invariant ring of the associated Weyl group, given by the fundamental characters of the corresponding Lie group. As an application, we give examples of elliptic surfaces with multiplicative reduction and all sections defined over Q for most of the entries of fiber configurations and Mordell–Weil lattices described by Oguiso and Shioda, as well as examples of explicit polynomials with Galois group W(E[subscript 7]) or W(E[subscript 8]).National Science Foundation (U.S.) (Career Grant DMS-0952486)Solomon Buchsbaum AT&T Research Fun
Algorithmic design of self-assembling structures
No full textWe study inverse statistical mechanics: how can one design a potential function so as to produce a specified ground state? In this article, we show that unexpectedly simple potential functions suffice for certain symmetrical configurations, and we apply techniques from coding and information theory to provide mathematical proof that the ground state has been achieved. These potential functions are required to be decreasing and convex, which rules out the use of potential wells. Furthermore, we give an algorithm for constructing a potential function with a desired ground state
Examples of abelian surfaces with everywhere good reduction
Full text linkWe describe several explicit examples of simple abelian surfaces over real quadratic fields with real multiplication and everywhere good reduction. These examples provide evidence for the Eichler–Shimura conjecture for Hilbert modular forms over a real quadratic field. Several of the examples also support a conjecture of Brumer and Kramer on abelian varieties associated to Siegel modular forms with paramodular level structures.National Science Foundation (U.S.) (Grant DMS-0952486)Solomon Buchsbaum AT&T Research Fun
Ground states and formal duality relations in the Gaussian core model
Full text linkWe study dimensional trends in ground states for soft-matter systems. Specifically, using a high-dimensional version of Parrinello-Rahman dynamics, we investigate the behavior of the Gaussian core model in up to eight dimensions. The results include unexpected geometric structures, with surprising anisotropy as well as formal duality relations. These duality relations suggest that the Gaussian core model possesses unexplored symmetries, and they have implications for a broad range of soft-core potentials.Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc
Using Elimination Theory to Construct Rigid Matrices
Full text linkOriginal manuscript September 23, 2012The rigidity of a matrix A for target rank r is the minimum number of entries of A that must be changed to ensure that the rank of the altered matrix is at most r. Since its introduction by Valiant (1977), rigidity and similar rank-robustness functions of matrices have found numerous applications in circuit complexity, communication complexity, and learning complexity. Almost all n × n matrices over an infinite field have a rigidity of (n − r)[superscript 2]. It is a long-standing open question to construct infinite families of explicit matrices even with superlinear rigidity when r = Ω(n).
In this paper, we construct an infinite family of complex matrices with the largest possible, i.e., (n − r)[superscript 2], rigidity. The entries of an n × n matrix in this family are distinct primitive roots of unity of orders roughly exp(n[superscript 2] log n). To the best of our knowledge, this is the first family of concrete (but not entirely explicit) matrices having maximal rigidity and a succinct algebraic description.
Our construction is based on elimination theory of polynomial ideals. In particular, we use results on the existence of polynomials in elimination ideals with effective degree upper bounds (effective Nullstellensatz). Using elementary algebraic geometry, we prove that the dimension of the affine variety of matrices of rigidity at most k is exactly n[superscript 2] – (n – r)[superscript 2] + k. Finally, we use elimination theory to examine whether the rigidity function is semicontinuous.National Science Foundation (U.S.) (CAREER Grant DMS-0952486
Recommended from our members
Rigidity of spherical codes
No full textA packing of spherical caps on the surface of a sphere (that is, a spherical code) is
called rigid or jammed if it is isolated within the space of packings. In other words,
aside from applying a global isometry, the packing cannot be deformed. In this
paper, we systematically study the rigidity of spherical codes, particularly
kissing configurations. One surprise is that the kissing configuration of the
Coxeter–Todd lattice is not jammed, despite being locally jammed (each
individual cap is held in place if its neighbors are fixed); in this respect, the
Coxeter–Todd lattice is analogous to the face-centered cubic lattice in three
dimensions. By contrast, we find that many other packings have jammed
kissing configurations, including the Barnes–Wall lattice and all of the best
kissing configurations known in four through twelve dimensions. Jamming
seems to become much less common for large kissing configurations in higher
dimensions, and in particular it fails for the best kissing configurations known in
25 through 31 dimensions. Motivated by this phenomenon, we find new kissing configurations in
these dimensions, which improve on the records set in 1982 by the laminated
lattices
- …
