6,697 research outputs found
The supermembrane revisited
The M2-brane is studied from the perspective of superembeddings. We review
the derivation of the M2-brane dynamics and the supergravity constraints from
the standard superembedding constraint and we discuss explicitly the induced
d=3, N=8 superconformal geometry on the worldvolume. We show that the gauged
supermembrane, for a target space with a U(1) isometry, is the standard
D2-brane in a type IIA supergravity background. In particular, the D2-brane
action, complete with the Dirac-Born-Infeld term, arises from the gauged
Wess-Zumino worldvolume 4-form via the brane action principle. The discussion
is extended to the massive D2-brane considered as a gauged supermembrane in a
massive D=11 superspace background. Type IIA supergeometry is derived using
Kaluza-Klein techniques in superspace.Comment: Latex, 46 pages, clarifying remarks and references adde
New old stones at Antiochia in Rough Cilicia: A novel city name and a proposed visit by Hadrian and Sabina
This article considers the evidence of newly discovered inscriptions from Antiochia ad Cragum in western Rough Cilicia and proposes two distinct observations: one, the city had an additional civic name different from that which is most commonly known; and two, the emperor Hadrian and Sabina may have visited the city and region during their journey from Egypt to Athens in 131 CE.
The excavations at the Roman-era city of Antiochia ad Cragum on the Turkish south coast have been ongoing since 2005, and since the beginning inscriptions have been discovered that shed helpful light on the history of the city. However, 2018 was an exceptional year for epigraphical discoveries in which several inscribed stones were found that challenge long-held notions about the city and add significantly to the historical record. Two of the inscriptions found that year offer the first instances on stone of a novel toponymic epithet for the city rather than the commonly held toponymic ad Cragum. The editiones principes of both, dealing solely with physical autopsy and textual reconstruction, have appeared separately.1 The current paper addresses the historical context of these inscriptions – civic nomenclature and possible imperial patronage in particular. The first section considers the formation of the city under Antiochus IV of Commagene and how these new inscriptions and known civic coinage reveal a different name than that by which the city is commonly known. In the second section, epigraphical evidence from one of the inscriptions is used to build a circumstantial case for a proposed visit to the city by Hadrian and Sabina in 131 CE as part of their westward journey from Egypt to Athens
Two-Dimensional Helioseismic Power, Phase, and Coherence Spectra of {\it Solar Dynamics Observatory} Photospheric and Chromospheric Observables
While the {\it Helioseismic and Magnetic Imager} (HMI) onboard the {\it Solar
Dynamics Observatory} (SDO) provides Doppler velocity [], continuum
intensity [], and line-depth [] observations, each of which is
sensitive to the five-minute acoustic spectrum, the {\it Atmospheric Imaging
Array} (AIA) also observes at wavelengths -- specifically the 1600 and 1700
Angstrom bands -- that are partly formed in the upper photosphere and have good
sensitivity to acoustic modes. In this article we consider the characteristics
of the spatio--temporal Fourier spectra in AIA and HMI observables for a
15-degree region around NOAA Active Region 11072. We map the
spatio--temporal-power distribution for the different observables and the HMI
Line Core [], or Continuum minus Line Depth, and the phase and coherence
functions for selected observable pairs, as a function of position and
frequency. Five-minute oscillation power in all observables is suppressed in
the sunspot and also in plage areas. Above the acoustic cut-off frequency, the
behaviour is more complicated: power in HMI is still suppressed in the
presence of surface magnetic fields, while power in HMI and the AIA bands
is suppressed in areas of surface field but enhanced in an extended area around
the active region, and power in HMI is enhanced in a narrow zone around
strong-field concentrations and suppressed in a wider surrounding area. The
relative phase of the observables, and their cross-coherence functions, are
also altered around the active region. These effects may help us to understand
the interaction of waves and magnetic fields in the different layers of the
photosphere, and will need to be taken into account in multi-wavelength local
helioseismic analysis of active regions.Comment: 18 pages, 15 figures, to be published in Solar Physic
Responsive and Responsible: Levels of Faculty Encouragement of Civic Engagement
This study explores how often faculty members encourage students to engage with campus, local, state, national, and global issues. Using data from the 2013 administration of the Faculty Survey of Student Engagement (FSSE), the results show that faculty members are more likely to encourage students to engage in state, national, or global issues than campus or local issues. Differences in faculty encouragement of civic engagement are also presented across gender, racial/ethnic identification, rank and employment status, and institutional affiliation, among other characteristics. Implications for practice are provided
The N=4 string is the same as the N=2 string
We redo the quantization of the N=4 string, taking into account the
reducibility of the constraints. The result is equivalent to the N=2 string,
with critical dimension D=4 and signature (++--). The N=4 formulation has
several advantages: the sigma-model field equations are implied classically,
rather than by quantum/beta-function calculations; self-duality/chirality is
one of the super-Virasoro constraints; SO(2,2) covariance is manifest. This
reveals that the theory includes fermions, and is apparently spacetime
supersymmetric.Comment: 7 pg (uuencoded dvi file; otherwise same as original
Relating Superembeddings and Non-linear Realisations
We discuss the relation between the superembedding method for deriving
worldvolume actions for D-branes and the method of Partially Broken Global
Supersymmetry based upon linear and non-linear realisations of SUSY. We give
the explicit relation for the cases of space filling branes in 3 and 4
dimensions and show that the standard F-constraint of the superembedding method
is the source of the required covariant non-linear constraints for the PBGS
method.Comment: 19 pages. Improved spelling, references adde
Sub-femtosecond absolute timing precision with a 10 GHz hybrid photonic-microwave oscillator
We present an optical-electronic approach to generating microwave signals
with high spectral purity. By circumventing shot noise and operating near
fundamental thermal limits, we demonstrate 10 GHz signals with an absolute
timing jitter for a single hybrid oscillator of 420 attoseconds (1Hz - 5 GHz)
Conformal and Superconformal Mechanics
We investigate the conformal and superconformal properties of a
non-relativistic spinning particle propagating in a curved background coupled
to a magnetic field and with a scalar potential. We derive the conditions on
the couplings for a large class of such systems which are necessary in order
their actions admit conformal and superconformal symmetry. We find that some of
these conditions can be encoded in the conformal and holomorphic geometry of
the background. Several new examples of conformal and superconformal models are
also given.Comment: 46 pages, Phyzzx.te
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