Application of single crystal superalloys for Earth-to-orbit propulsion systems

Single crystal superalloys were first identified as potentially useful engineering materials for aircraft gas turbine engines in the mid-1960's. Although they were not introduced into service as turbine blades in commercial aircraft engines until the early 1980's, they have subsequently accumulated tens of millions of flight hours in revenue producing service. The space shuttle main engine (SSME) and potential advanced earth-to-orbit propulsion systems impose severe conditions on turbopump turbine blades which for some potential failure modes are more severe than in aircraft gas turbines. Research activities which are directed at evaluating the potential for single crystal superalloys for application as turbopump turbine blades in the SSME and advanced rocket engines are discussed. The mechanical properties of these alloys are summarized and the effects of hydrogen are noted. The use of high gradient directional solidification and hot isostatic pressing to improve fatigue properties is also addressed

Comment on "Modifying the variational principle in the action integral functional derivation of time-dependent density functional theory" by Jochen Schirmer [arXiv:1010.4223]

In a paper recently published in Phys. Rev. A [arXiv:1010.4223], Schirmer has criticized an earlier work of mine [arXiv:0803.2727], as well as the foundations of time-dependent density functional theory. In Ref.[2], I showed that the so-called "causality paradox" - i.e., the failure of the exchange-correlation potential derived from the Runge-Gross time-dependent variational principle to satisfy causality requirements - can be solved by a careful reformulation of that variational principle. Fortunately, the criticism presented in Ref.[1] is based on elementary misunderstandings of the nature of functionals, gauge transformations, and the time-dependent variational principle. In this Comment I wish to point out and clear these misunderstandings.Comment: 4 pages. Accepted for publication in Phys. Rev.

Random-phase-approximation-based correlation energy functionals: Benchmark results for atoms

The random phase approximation (RPA) for the correlation energy functional of density functional theory has recently attracted renewed interest. Formulated in terms of the Kohn-Sham (KS) orbitals and eigenvalues, it promises to resolve some of the fundamental limitations of the local density and generalized gradient approximations, as for instance their inability to account for dispersion forces. First results for atoms, however, indicate that the RPA overestimates correlation effects as much as the orbital-dependent functional obtained by a second order perturbation expansion on the basis of the KS Hamiltonian. In this contribution, three simple extensions of the RPA are examined, (a) its augmentation by an LDA for short-range correlation, (b) its combination with the second order exchange term, and (c) its combination with a partial resummation of the perturbation series including the second order exchange. It is found that the ground state and correlation energies as well as the ionization potentials resulting from the extensions (a) and (c) for closed sub-shell atoms are clearly superior to those obtained with the unmodified RPA. Quite some effort is made to ensure highly converged RPA data, so that the results may serve as benchmark data. The numerical techniques developed in this context, in particular for the inherent frequency integration, should also be useful for applications of RPA-type functionals to more complex systems.Comment: 11 pages, 7 figure

Unsettled territory

In a surreal manner, my work tests the burgeoning notion of art as life and life as art. Artistic effort to be more real than reality has a long tradition, but it is beginning with Marcel Duchamp that the particular turn of mind which fascinates me becomes evident in art. The overwhelming doubt in regard to the finality of a proposition is the motivation for my representation of experience. In my work there is a focus on seemingly commonplace events, objects, and forms whose significance has been enhanced in an ambiguous statement. In a new context specific objects and materials function in relationships foreign to their identity. A certain credibility in this new identity makes them psychologically provocative. My use of objects reflects the influence of Jasper Johns, Robert Rauchenberg, and Rene Magrite. They used objects in an overtly confrontational manner. In my work there is a reserved atmosphere where the confrontation is denied. The impermanent, unprecious nature of the materials is a part of the fast changing, disposable attitude in my modem society. The imposing presence of the work contradicts impermanence, and this creates a paradox by presenting miscellaneous objects in a precious manner. Feelings of static confinement are tempered by unresolved spontaneity. These opposing qualities are subtle and achieve a form of coexistence. In content the use of human manipulation echos man's mimicry of natural order. Levels of order reflect my personal beliefs about their psychological functioning. I propose an ordered atmosphere of reserved human normalcy where tensions and contradictions arise, build, and expire

Feminist Narrative and Lemonade

Colene LindThis essay uses feminist and narrative criticism to analyze the multiple messages produced in the popular culture visual album Lemonade. The relevance of these messages and their distinct interpretations to current sociopolitical problems in American society are addressed and the sociohistorical context, specifically in terms of race relations in the United States, is established. Intersectionality is explored as an aid to established critical theories such as those employed in this analysis. Key features of the cultural artifact such as the central narrative, Black feminism, and empowerment are analyzed in depth. Metaphors are established as a way of allowing for multiple interpretations of different aspects of the artifact such as lyrics and visuals. Finally, implications for the current and future state of American society are discussed

Canyon

Art history paper.1985 Spring.Includes bibliographic references (page 15)

Evaluation of Oral Function Before and After Frenectomy in Breastfed Infants Diagnosed with Tethered Oral Tissue

Assessment and treatment of tethered oral tissue, or tongue tie, vary within and across providers, resulting in inconsistent surgical and therapeutic outcomes. Assessment and treatment have historically focused on the anatomical (structural) underpinnings of tongue tie, as opposed to the physiological (functional) aspects that can affect daily activities. This is particularly noteworthy in the infant population in regards to breastfeeding. Clinical findings, however, suggest that connections exist between tongue tie and a variety of other oral functions that go beyond breastfeeding. The goal of this research was to examine a relatively small group of breastfed infants with tethered oral tissue holistically prior to and at one week and three weeks following surgical intervention for tethered oral tissue using a particular laser (i.e., frenectomy). Data were obtained through direct observation of structural and behavioral changes, as well as a parent questionnaire. Questionnaire results indicated problems across a wide spectrum of oral dysfunction symptoms known to be associated with tethered oral tissue and of perceived changes post-operatively. The role of supplemental aftercare therapy following frenectomy and its perceived value were discussed. In addition, the role of supplemental therapy as a form of non-surgical intervention was examined using a small sample size. This research suggested that differences exist in oral function of the infant and for maternal breastfeeding complications before and after frenectomy, but that these differences are not dependent on the appearance (or perceived visual severity) of the restrictive tissue. Evaluation of the whole child and the breastfeeding dyad together is critical to determine the relationship between anatomic structure and function. Surgical intervention for the treatment of tethered oral tissue, as well as therapeutic care from a skilled provider, should be considered for breastfeeding dyads who exhibit signs and symptoms of oral dysfunction