1,725 research outputs found
Where to find Christian philosophy?: Spatiality in John Chrysostom’s counter to Greek Paideia
This article examines the use of the concept philosophia in the writings and homilies of John Chrysostom. Although Chrysostom in his discussion of intellectual achievements draws on a long-standing tradition of Christian apologetics, he lends a new direction to the debate by highlighting the spatiality of philosophy. He not only counters Hellenic paideia with Christian wisdom, but locates these two types of philosophy in the city and the countryside, respectively. The article argues that the spatial dimension is vital to Chrysostom’s view of philosophy as he aims to extend the rural ideal of asceticism to the polis to create a healthy Christian community within the city
Magnetic field mapper
Magnetic field mapper locates imperfections in cadmium sulphide solar cells by detecting and displaying the variations of the normal component of the magnetic field resulting from current density variations. It can also inspect for nonuniformities in other electrically conductive materials
Performance limitations of subband adaptive filters
In this paper, we evaluate the performance limitations of subband adaptive filters in terms of achievable final error terms. The limiting factors are the aliasing level in the subbands, which poses a distortion and thus presents a lower bound for the minimum mean squared error in each subband, and the distortion function of the overall filter bank, which in a system identification setup restricts the accuracy of the equivalent fullband model. Using a generalized DFT modulated filter bank for the subband decomposition, both errors can be stated in terms of the underlying prototype filter. If a source model for coloured input signals is available, it is also possible to calculate the power spectral densities in both subbands and reconstructed fullband. The predicted limits of error quantities compare favourably with simulations presented
‘Other’ spaces in ancient civilization – Christian asceticism as heterotopia
This article discusses how classical studies can use the concept of heterotopia to analyze both physical and imagined spaces in ancient civilizations. Michel Foucault has adopted the notion of heterotopia to refer to spaces and places that exist in reality, but are strikingly different from the surrounding space and reflect, negate and invert it. First, Foucault’s criteria for such other spaces are presented, and the concept of heterotopia is critically discussed before applications in ancient studies are outlined. Finally it is shown, as an example, how Foucault’s approach can help to understand the ideology and practice of ascetic monasticism in the Greek East in Late Antiquity
Coreless and singular vortex lattices in rotating spinor Bose-Einstein condensates
We theoretically investigate vortex-lattice phases of rotating spinor
Bose-Einstein condensates (BEC) with the ferromagnetic spin-interaction by
numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow
rotation can sustain a rich variety of exotic vortices due to the
multi-component order parameters, such as the Mermin-Ho and Anderson-Toulouse
coreless vortices (the 2-dimensional skyrmion and meron) and the
non-axisymmetric vortices with the sifting vortex cores. Here, we present the
spin texture of various vortex-lattice states at higher rotation rates and in
the presence of the external magnetic field. In addition, the vortex phase
diagram is constructed in the plane by the total magnetization and the
external rotation frequency by comparing the free energies of possible
vortices. It is shown that the vortex phase diagram in a - plane may
be divided into two categories; (i) the coreless vortex lattice formed by the
several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the
cores with the pure polar (antiferromagnetic) state. In particular, it is found
that the type-(ii) state forms the composite lattices of coreless and
polar-core vortices. The difference between the type-(i) and type-(ii) results
from the existence of the singularity of the spin textures, which may be
experimentally confirmed by the spin imaging within polarized light recently
proposed by Carusotto and Mueller. We also discussed on the stability of
triangular and square lattice states for rapidly rotating condensates.Comment: to be published in Phys. Rev.
Spin textures in rotating two-component Bose-Einstein condensates
We investigate two kinds of coreless vortices with axisymmetric and
nonaxisymmetric configurations in rotating two-component Bose-Einstein
condensates. Starting from the Gross-Pitaevskii energy functional in a rotating
frame, we derive a nonlinear sigma model generalized to the two-component
condensates. In terms of a pseudospin representation, an axisymmetric vortex
and a nonaxisymmetric one correspond to spin textures referred to as a
"skyrmion" and a "meron-pair", respectively. A variational method is used to
investigate the dependence of the sizes of the stable spin textures on system
parameters, and the optimized variational function is found to reproduce well
the numerical solution. In the SU(2) symmetric case, the optimal skyrmion and
meron-pair are degenerate and transform to each other by a rotation of the
pseudospin. An external rf-field that couples coherently the hyperfine states
of two components breaks the degeneracy in favor of the meron-pair texture due
to an effective transverse pseudomagnetic field. The difference between the
intracomponent and intercomponent interactions yields a longitudinal
pseudomagnetic field and a ferromagnetic or an antiferromagnetic pseudospin
interaction, leading to a meron-pair texture with an anisotropic distribution
of vorticity.Comment: 14 pages, 15 figure
How the Carbon to Nitrogen Ration Affects Soil Microorganisms
This slide presentation for the Natural Sciences Poster Session at Parkland College presents information on the importance of the correct ratio between nitrogen and carbon for microorganism health
Dating of streamwater using tritium in a post nuclear bomb pulse world: continuous variation of mean transit time with streamflow
Tritium measurements of streamwater draining the Toenepi catchment, a small dairy farming area in Waikato, New Zealand, have shown that the mean transit time of the water varies with the flow rate of the stream. Mean transit times through the catchment are 2–5 years during high baseflow conditions in winter, increasing to 30–40 years as baseflow decreases in summer, and then dramatically older water during drought conditions with mean transit time of more than 100 years. Older water is gained in the lower reaches of the stream, compared to younger water in the headwater catchment. The groundwater store supplying baseflow was estimated from the mean transit time and average baseflow to be 15.4 × 10<sup>6</sup> m<sup>3</sup> of water, about 1 m water equivalent over the catchment and 2.3 times total annual streamflow. Nitrate is relatively high at higher flow rates in winter, but is low at times of low flow with old water. This reflects both lower nitrate loading in the catchment several decades ago as compared to current intensive dairy farming, and denitrification processes occurring in the older groundwater. Silica, leached from the aquifer material and accumulating in the water in proportion to contact time, is high at times of low streamflow with old water. There was a good correlation between silica concentration and streamwater age, which potentially allows silica concentrations to be used as a proxy for age when calibrated by tritium measurements. This study shows that tritium dating of stream water is possible with single tritium measurements now that bomb-test tritium has effectively disappeared from hydrological systems in New Zealand, without the need for time-series data
Superradiant light scattering and grating formation in cold atomic vapours
A semi-classical theory of coherent light scattering from an elongated sample
of cold atoms exposed to an off-resonant laser beam is presented. The model,
which is a direct extension of that of the collective atomic recoil laser
(CARL), describes the emission of two superradiant pulses along the sample's
major axis simultaneous with the formation of a bidimensional atomic grating
inside the sample. It provides a simple physical picture of the recent
observation of collective light scattering from a Bose-Einstein condensate [S.
Inouye et al., Science N.285, p. 571 (1999)]. In addition, the model provides
an analytical description of the temporal evolution of the scattered light
intensity which shows good quantitative agreement with the experimental results
of Inouye et al.Comment: submitted to Optics Communications, LaTex version, 2 postscript
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