30,080 research outputs found
Duration of magnetic field(s) acting on meteorite parent body(s)
An overview is presented on the efforts being made to estimate the time that the magnetic field(s) existed and acted on meteorite parent bodies. The basic premise is that if a sample exhibits a low K-Ar age, it is the requisite amount of Ar-40. This assumption is applied to a preliminary analysis of the Farmington chondrite
Sex Ratio and Sexual Dimorphism in \u3ci\u3eFormica Exsectoides\u3c/i\u3e, the Allegheny Mound Ant (Hymenoptera: Formicidae)
We excavated 66 mounds from 6 populations of Formica exsectoides in Michigan jack pine, collecting sexual caste pupae for sex ratio estimates and measurement of dimorphism. Reproductive caste brood was present in only 37 ofthe 66 mounds, and presence of reproductive caste brood was associated with larger mound surface area. Females were heavier than males, but did not differ from males in energy density. Sexes did not differ in timing or rate of development. Sex ratio estimates based on individual mounds ranged from 1.0 (all male) to 0.08 (female·biased). Four of the six study populations were strongly male·biased, while sex ratio estimates for the remaining populations did not differ from equal investment. While this interpopulation variation may be caused by genetic factors, the equal investment populations were 10· cated in or near patches of clear·cut forest, suggesting that environmental impacts should be investigated
Magnetism in meteorites
An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered
Prediction of unsteady aerodynamic loadings caused by leading edge and trailing edge control surface motions in subsonic compressible flow: Computer program description
A digital computer program has been developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge or trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges have been extracted analytically as a preliminary step to solving the integral equation by collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accommodated
Dual pairing of symmetry groups and dynamical groups in physics
This article reviews many manifestations and applications of dual
representations of pairs of groups, primarily in atomic and nuclear physics.
Examples are given to show how such paired representations are powerful aids in
understanding the dynamics associated with shell-model coupling schemes and in
identifying the physical situations for which a given scheme is most
appropriate. In particular, they suggest model Hamiltonians that are diagonal
in the various coupling schemes. The dual pairing of group representations has
been applied profitably in mathematics to the study of invariant theory. We
show that parallel applications to the theory of symmetry and dynamical groups
in physics are equally valuable. In particular, the pairing of the
representations of a discrete group with those of a continuous Lie group or
those of a compact Lie with those of a non-compact Lie group makes it possible
to infer many properties of difficult groups from those of simpler groups. This
review starts with the representations of the symmetric and unitary groups,
which are used extensively in the many-particle quantum mechanics of bosonic
and fermionic systems. It gives a summary of the many solutions and
computational techniques for solving problems that arise in applications of
symmetry methods in physics and which result from the famous Schur-Weyl duality
theorem for the pairing of these representations. It continues to examine many
chains of symmetry groups and dual chains of dynamical groups associated with
the several coupling schemes in atomic and nuclear shell models and the
valuable insights and applications that result from this examination.Comment: 51 pages, 5 figures and 5 table
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What can co-speech gestures in aphasia tell us about the relationship between language and gesture?: A single case study of a participant with Conduction Aphasia
Cross-linguistic evidence suggests that language typology influences how people gesture when using ‘manner-of-motion’ verbs (Kita 2000; Kita & Özyürek 2003) and that this is due to ‘online’ lexical and syntactic choices made at the time of speaking (Kita, Özyürek, Allen, Brown, Furman & Ishizuka, 2007). This paper attempts to relate these findings to the co-speech iconic gesture used by an English speaker with conduction aphasia (LT) and five controls describing a Sylvester and Tweety1 cartoon. LT produced co-speech gesture which showed distinct patterns which we relate to different aspects of her language impairment, and the lexical and syntactic choices she made during her narrative
Scalable photonic quantum computation through cavity-assisted interaction
We propose a scheme for scalable photonic quantum computation based on cavity
assisted interaction between single-photon pulses. The prototypical quantum
controlled phase-flip gate between the single-photon pulses is achieved by
successively reflecting them from an optical cavity with a single-trapped atom.
Our proposed protocol is shown to be robust to practical nose and experimental
imperfections in current cavity-QED setups.Comment: 5 pages, 2 figure
Constraints of magnetic field which magnetized the Farmington meteorite parant body
Analysis indicates the following: (1) the parent body of the Farmington meteorite experienced sufficient heating (probably from shock accompanying a major collision occurring 520 million years ago) to erase the record of any magnetization acquired prior to that event; therefore, (2)the observed magnetization in the Farmington meteorite must have been acquired after the collision; and (3)shockproduced magnetization is unlikely, because of the finite cooling time indicated by the burial depth of approximately several meters. The possibility of shock or irradiation-produced magnetizations is proposed as an experimental study, even though neither appears likely to have produced the magnetic field which produced the magnetization in the parent body of the Farmington meteorite
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