22,300 research outputs found
Notes on Spinoptics in a Stationary Spacetime
In arXiv:1105.5629, equations of the modified geometrical optics for
circularly polarized photon trajectories in a stationary spacetime are derived
by using a (1+3)-decomposed form of Maxwell's equations. We derive the same
results by using a four-dimensional covariant description. In our procedure,
the null nature of the modified photon trajectory naturally appears and the
energy flux is apparently null. We find that, in contrast to the standard
geometrical optics, the inner product of the stationary Killing vector and the
tangent null vector to the modified photon trajectory is no longer a conserved
quantity along light paths. This quantity is furthermore different for left and
right handed photon. A similar analysis is performed for gravitational waves
and an additional factor of 2 appears in the modification due to the spin-2
nature of gravitational waves.Comment: 15 pages, to appear in PR
Long-Wavelength Excesses in Two Highly Obscured High-Mass X-Ray Binaries: IGR J16318ā4848 and GX 301ā2
We present evidence for excess long-wavelength emission from two high-mass X-ray binaries, IGR J16318-4848 and GX 301-2, that show enormous obscuration (N_H ā 10^(23)-10^(24) cm^(-2)) in their X-ray spectra. Using archival near- and mid-infrared data, we show that the spectral energy distributions of IGR J16318-4848 and GX 301-2 are substantially higher in the mid-infrared than their expected stellar emission. We successfully fit the excesses with ~1000 K blackbodies, which suggests that they are due to warm circumstellar dust that also gives rise to the X-ray absorption. However, we need further observations to constrain the detailed properties of the excesses. This discovery highlights the importance of mid-infrared observations for understanding highly obscured X-ray binaries
World Agriculture Organization (WAO): New Global Governance for Agricultural Trade
It is increasingly questionable whether the WTO regime is the most appropriate form of governance for addressing global problems related to agriculture. In particular, climate change, sustainability, hunger/poverty in developing countries, and expected imbalance in food demand-supply by 2050 are emerging as grave challenges to humanity and the WTO is still struggling to resolve issues (related to the multifunctional roles of agriculture) of the 20th century while completely lacking the capacity to tackle such new global issues of the 21st century. Given this outmoded institution, the primary objective of this article is to propose that a new system of governance is needed so as to exclusively and effectively deal with problems arising from the interactions among climate change, agricultural sustainability, food security, and trade.Global public goods, climate change, sustainable agriculture, food security, WTO, agricultural trade, International Relations/Trade,
MB 745 Leading Development Programs in Mission
Text books: a. Conflict Mediation Across Cultures, by David Augsburger (310 pp) b. African Friends and Money Matters, by David Maranz (224 pp) c. Orality and Literacy, by Walter Ong (201 pp) d. None of These Diseases: The Bibleās Health Secrets for the 21st Century, Millennium Three Edition, by S.I. McMillen and David E. Stern (285 pp) e. Students choose 200 pp of reading in their area of interest related to development in mission. A book can be picked from the bibliography or a suggestion submitted to the professor for approval.https://place.asburyseminary.edu/syllabi/3930/thumbnail.jp
Quantum Hall Ferromagnets: Induced Topological term and electromagnetic interactions
The quantum Hall ground state in materials like GaAs is well known
to be ferromagnetic in nature. The exchange part of the Coulomb interaction
provides the necessary attractive force to align the electron spins
spontaneously. The gapless Goldstone modes are the angular deviations of the
magnetisation vector from its fixed ground state orientation. Furthermore, the
system is known to support electrically charged spin skyrmion configurations.
It has been claimed in the literature that these skyrmions are fermionic owing
to an induced topological Hopf term in the effective action governing the
Goldstone modes. However, objections have been raised against the method by
which this term has been obtained from the microscopics of the system. In this
article, we use the technique of the derivative expansion to derive, in an
unambiguous manner, the effective action of the angular degrees of freedom,
including the Hopf term. Furthermore, we have coupled perturbative
electromagnetic fields to the microscopic fermionic system in order to study
their effect on the spin excitations. We have obtained an elegant expression
for the electromagnetic coupling of the angular variables describing these spin
excitations.Comment: 23 pages, Plain TeX, no figure
MB 780 Cross-Cultural Christian Discipling
A study of the role of ritual process in the shaping of believers. Rites and ceremonies, especially initiatory rites, from a variety of religious traditions provide both models of the role of ritual in the formation and nurture of persons and models for discipling Christian converts, especially those from traditional religious backgrounds. Students will construct their own structures for the discipling task based upon the insights and models provided by the course.https://place.asburyseminary.edu/syllabi/1330/thumbnail.jp
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