31,240 research outputs found
Role of relativity and nucleon compositeness in few-body systems
Recent progress is reviewed in four areas where new experimental data have
been obtained: proton-proton bremsstrahlung, threshold pion production in
proton-proton collisions, elastic electron-deuteron scattering and deuteron
photodisintegration at several GeV photon energy. Relativistic effects are
expected to be significant in these processes. High energy photodisintegration
suggests that partonic behavior could be relevant in subamplitudes at large
momentum transfer.Comment: Invited talk at XVII European Conference on Few-Body Problems in
Physics, Sept. 11-16, 2000, Evora, Portugal. (12 pages, 2 postscript figures
Deferred compensation and gift exchange: an experimental investigation into multi-period labor markets
This paper examines the relationship between firmsâ wage offers and workersâ
supply of effort using a three-period experiment. In equilibrium, firms will offer deferred
compensation: first period productivity is positive and wages are zero, while third period
productivity is zero and wages are positive. The experiment produces strong evidence
that deferred compensation increases worker effort; in about 70 percent of cases subjects
supplied the optimal effort given the wage offer, and there was a strong effort response to
future-period wages. We also find some evidence of gift exchange; worker players
increased the effort levels in response to above equilibrium wage offers by a human, but
not in response to similar offers by a computer. Finally, we find that firm players who are
initially hesitant to defer compensation learn over time that it is beneficial to do so
A covariant gauge-invariant three-dimensional description of relativistic bound-states
A formalism is presented which allows covariant three-dimensional bound-state
equations to be derived systematically from four-dimensional ones without the
use of delta-functions. The amplitude for the interaction of a bound state
described by these equations with an electromagnetic probe is constructed. This
amplitude is shown to be gauge invariant if the formalism is truncated at the
same coupling-constant order in both the interaction kernel of the integral
equation and the electromagnetic current operator.Comment: 17 pages, RevTeX, uses BoxedEPS.te
Low-energy interaction of composite spin-half systems with scalar and vector fields
We consider a composite spin-half particle moving in spatially-varying scalar
and vector fields. The vector field is assumed to couple to a conserved charge,
but no assumption is made about either the structure of the composite or its
coupling to the scalar field. A general form for the piece of the spin-orbit
interaction of the composite with the scalar and vector fields which is
first-order in momentum transfer and second-order in the fields is
derived.Comment: 10 pages, RevTe
MOSAIC: An integrated ultrasonic 2-D array system
An investigation into the development of an ultrasound imaging system capable of customization for multiple applications via the tessellation of in-system programmable scalable modules, or tiles, is presented here. Each tile contains an individual ultrasonic array, operating at +/-3.3V, which can be assembled into a larger âmosaicâ of multiple tiles to create arrays of any size or shape. The ability to form an imaging system from generic building blocks which are physically identical for manufacturing purposes yet functionally unique via programming to suit the application has many potential benefits in the field of ultrasonics. The system is primarily targeted at underwater sonar and non-destructive testing, as defined by the current excitation frequency, but the concept is equally applicable to applications in biomedical ultrasound
Publications of the exobiology program for 1984: A special bibliography
A bibliography of NASA exobiology programs is given. Planetary environments; chemical evolution; organic geochemistry; extraterrestrial intelligence; and the effect of planetary solar and astrophysical phenomena on the evolution of complex life in the universe are among the topics listed
Modified eutectic alloys for high temperature service Six month progress report
Eutectic alloys of cobalt and nickel modified by tungsten for use at high temperature
Modified eutectic alloys for high temperature service Semiannual progress report
Structural modification of high temperature superalloy
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