Nonlinear dynamic Interactions between flow-induced galloping and shell-like buckling

Acknowledgement The research of J.S. is supported by EPSRC Grant EP/J010820/1.Peer reviewedPublisher PD

Reaction mechanisms of pair transfer

The mechanisms of nuclear transfer reactions are described for the transfer of two nucleons from one nucleus to another. Two-nucleon overlap functions are defined in various coordinate systems, and their transformation coefficients given between coordinate systems. Post and prior couplings are defined for sequential transfer mechanisms, and it is demonstrated that the combination of `prior-post' couplings avoids non-orthogonality terms, but does not avoid couplings that do not have good zero-range approximations. The simultaneous and sequential mechanisms are demonstrated for the $^{124}$Sn(p,t)$^{122}$Sn reaction at 25 MeV using shell-model overlap functions. The interference between the various simultaneous and sequential amplitudes is shown.Comment: 14 pages, 3 figures, chapter 34 in "50 Years of Nuclear BCS", edited by R. A. Broglia and V. Zelevinsky: ISBN 978-981-4412-48-3 Uses WS macros (included). Corrected text and calculations as in the published versio

Gamma-Ray Pulsar Studies with GLAST

Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.Comment: 8 pages, 5 figures. To appear in the proceedings of "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007, McGill University, Montreal, Canad

The Empath’s Travel Log

Cynthia Marie Hoffman Studner said of the poem, This is an ambitious poem that delivers on empathy, just as promised. The poem establishes a metaphor of a “taught thread” that pulls together the traveler and an “orange-coated mutt” spotted in Italy, and this thread weaves throughout the poem as one of continual and deep connection with others. One wonders of the empath’s fate, especially when the poem begins with the story of wives cremated beside their dead husbands. What are the implications of this empathy in terms of its being something the speaker must bear? At times, it is guilt, as in the case of the baby rabbit that cannot be saved. Later, it is the insensitivity of a father who laughs and orders a rabbit cooked and delivered on a plate. It seems the speaker ultimately comes to find purpose and usefulness in empathy, saving animals after all (making the dream come true in which “the thread connecting/ me to you does not snap,/ and you live,/ and you live”). But it is the stark absence of animals and others in the final section that haunts me. The tension and strangeness in the ending lines is satisfying in a way that resists closure. I want more, but at the same time, I don’t want more. And that seems just right

Unread Letters to My Mother

The poem Unread Letters to My Mother is a meditation on dream and memory and how PTSD brought on by childhood trauma has effected those things within the speaker\u27s life. Each of the seven sections are addressed to the speaker\u27s mother, but the reader knows these are things which are left unsaid, in the darkness, as the clarity and insight they provide into the speaker\u27s life is perhaps too overwhelming for the figure of the mother to process

Space Detectors for Gamma Rays (100 MeV - 100 GeV): from EGRET to Fermi LAT

The design of spaceborne high-energy (E>100 MeV) gamma-ray detectors depends on two principal factors: (1) the basic physics of detecting and measuring the properties of the gamma rays; and (2) the constraints of operating such a detector in space for an extended period. Improvements in technology have enabled major advances in detector performance, as illustrated by two successful instruments, EGRET on the Compton Gamma Ray Observatory and LAT on the Fermi Gamma-ray Space Telescope.Comment: 11 pages, 7 figures, submitted to Comptes Rendus Physiqu

A Survey of Composite Grid Generation for General Three-dimensional Sections

The generation and use of composite grids for general three-dimensional physical boundary configurations is discussed, and the availability of several codes or procedures is noted. With the composite framework, the physical region is segmented into sub-regions, each bounded by six curved sides, and a grid is generated in each sub-region. These grids may be joined at the interfaces between the sub-regions with various degrees of continuity. This structure allows codes to be constructed to operate on rectangular blocks in computational space, so that existing solution procedures can be readily incorporated in the construction of codes for general configurations. Numerical grid generation is an integral part of the numerical solution of partial differential equations and is one of the pacing items in the development of codes for general configurations. The numerically generated grid frees the computational simulation from restriction to certain boundary shapes and allows general codes to be written in which the boundary shape is specified simply by input. The numerically generated grid allows all computation to be done on a fixed square grid in the computational space, which is always rectangular by construction