1,589 research outputs found
Experiments on the injection and containment of electron clouds in a toroidal apparatus
Injection and containment of electron clouds in azimuthally symmetric, toroidal apparatu
An ion resonance instability in grossly non-neutral plasmas
Ion resonance instability in grossly non-neutral plasma
Magnetospheric eclipses in the double pulsar system J0737-3039
We argue that eclipses of radio emission from the millisecond pulsar A in the
double pulsar system J0737-3039 are due to synchrotron absorption by plasma in
the closed field line region of the magnetosphere of its normal pulsar
companion B. A's radio beam only illuminates B's magnetosphere for about 10
minutes surrounding the time of eclipse. During this time it heats particles at
r\gtrsim 10^9 cm to relativistic energies and enables extra plasma to be
trapped by magnetic mirroring. An enhancement of the plasma density by a factor
\sim 10^2 is required to match the duration and optical depth of the observed
eclipses. The extra plasma might be supplied by a source near B through B\gamma
pair creation by energetic photons produced in B's outer gap. Excitation of
pairs' gyrational motions by cyclotron absorption of A's radio beam can result
in their becoming trapped between conjugate mirror points in B's magnetosphere.
Because the trapping efficiency decreases with increasing optical depth, the
plasma density enhancement saturates even under steady state illumination. The
result is an eclipse with finite, frequency dependent, optical depth. After
illumination by A's radio beam ceases, the trapped particles cool and are lost.
The entire cycle repeats every orbital period. We speculate that the
asymmetries between eclipse ingress and egress result in part from the
magnetosphere's evolution toward a steady state when illuminated by A's radio
beam. We predict that A's linear polarization will vary with both eclipse phase
and B's rotational phase.Comment: 8 pages, 1 figure, submitted to ApJ, references corrected,
detectability of reprocessed emission revised, major conclusions unchange
Profit contribution information’s impact on internal integration
An exploratory quantitative study on the relationship between profit contribution information and firm-wide internal integration is presented. Specifically, the authors examine how profit contribution information availability impacts firm-wide internal integration and, subsequently, logistics performance. This study provides greater insight into the area; only a few studies have empirically examined the impact of profit contribution information within a firm. The primary implication is that firms should utilize specific types of information, i.e. profit contribution information, for making more informed operational and strategic decisions. The paper also underscores the managerial value of using profit contribution information in decision making and planning
Developing reverse logistics programs: A resource based view
Previous research proposes a six-process model for reverse logistics (RL) program design and execution. This manuscript advances RL related knowledge by incorporating the previous model into a broader theoretical framework, namely, the Resource Based View (RBV) of the firm. The current research employs exploratory techniques to investigate the applicability of RBV and its main tenants within the RL context. Based on in-depth interviews with 16 executives from seven different companies, the relationships among resources. RL capabilities, and RL competencies are explored
Mathematical models of bipolar disorder
We use limit cycle oscillators to model bipolar II disorder, which is characterized by alternating hypomanic and depressive episodes and afflicts about 1% of the United States adult population. We consider two non-linear oscillator models of a single bipolar patient. In both frameworks, we begin with an untreated individual and examine the mathematical effects and resulting biological consequences of treatment. We also briefly consider the dynamics of interacting bipolar II individuals using weakly-coupled, weakly-damped harmonic oscillators. We discuss how the proposed models can be used as a framework for refined models that incorporate additional biological data. We conclude with a discussion of possible generalizations of our work, as there are several biologically-motivated extensions that can be readily incorporated into the series of models presented here
User interface development and metadata considerations for the Atmospheric Radiation Measurement (ARM) archive
This paper will discuss user interface development and the structure and use of metadata for the Atmospheric Radiation Measurement (ARM) Archive. The ARM Archive, located at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, is the data repository for the U.S. Department of Energy's (DOE's) ARM Project. After a short description of the ARM Project and the ARM Archive's role, we will consider the philosophy and goals, constraints, and prototype implementation of the user interface for the archive. We will also describe the metadata that are stored at the archive and support the user interface
X-ray Phase-Resolved Spectroscopy of PSRs B0531+21, B1509-58, and B0540-69 with RXTE
The Rossi X-ray Timing Explorer ({\sl RXTE}) has made hundreds of
observations on three famous young pulsars (PSRs) B0531+21 (Crab), B1509-58,
and B0540-69. Using the archive {\sl RXTE} data, we have studied the
phase-resolved spectral properties of these pulsars in details. The variation
of the X-ray spectrum with phase of PSR B0531+21 is confirmed here much more
precisely and more details are revealed than the previous studies: the spectrum
softens from the beginning of the first pulse, turns to harden right at the
pulse peak and becomes the hardest at the bottom of the bridge, softens
gradually until the second peak, and then softens rapidly. Different from the
previous studies, we found that the spectrum of PSR B1509-58 is significantly
harder in the center of the pulse, which is also in contrast to that of PSR
B0531+21. The variation of the X-ray spectrum of PSR B0540-69 seems similar to
that of PSR B1509-58, but with a lower significance. Using the about 10 years
of data span, we also studied the real time evolution of the spectra of these
pulsars, and no significant evolution has been detected. We have discussed
about the constraints of these results on theoretical models of pulsar X-ray
emission.Comment: 42 pages, 24 figure
Electron-Positron Jets from a Critically Magnetized Black Hole
The curved spacetime surrounding a rotating black hole dramatically alters
the structure of nearby electromagnetic fields. The Wald field which is an
asymptotically uniform magnetic field aligned with the angular momentum of the
hole provides a convenient starting point to analyze the effects of radiative
corrections on electrodynamics in curved spacetime. Since the curvature of the
spacetime is small on the scale of the electron's Compton wavelength, the tools
of quantum field theory in flat spacetime are reliable and show that a rotating
black hole immersed in a magnetic field approaching the quantum critical value
of ~G cm is unstable. Specifically, a maximally rotating
three-solar-mass black hole immersed in a magnetic field of ~G would be a copious producer of electron-positron pairs with a
luminosity of erg s.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
Unstable states in QED of strong magnetic fields
We question the use of stable asymptotic scattering states in QED of strong
magnetic fields. To correctly describe excited Landau states and photons above
the pair creation threshold the asymptotic fields are chosen as generalized
Licht fields. In this way the off-shell behavior of unstable particles is
automatically taken into account, and the resonant divergences that occur in
scattering cross sections in the presence of a strong external magnetic field
are avoided. While in a limiting case the conventional electron propagator with
Breit-Wigner form is obtained, in this formalism it is also possible to
calculate -matrix elements with external unstable particles.Comment: Revtex, 7 pages. To appear in Phys. Rev. D53(2
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