64 research outputs found
Structure and Stability of Keplerian MHD Jets
MHD jet equilibria that depend on source properties are obtained using a
simplified model for stationary, axisymmetric and rotating magnetized outflows.
The present rotation laws are more complex than previously considered and
include a Keplerian disc. The ensuing jets have a dense, current-carrying
central core surrounded by an outer collar with a return current. The
intermediate part of the jet is almost current-free and is magnetically
dominated. Most of the momentum is located around the axis in the dense core
and this region is likely to dominate the dynamics of the jet. We address the
linear stability and the non-linear development of instabilities for our models
using both analytical and 2.5-D numerical simulation's. The instabilities seen
in the simulations develop with a wavelength and growth time that are well
matched by the stability analysis. The modes explored in this work may provide
a natural explanation for knots observed in astrophysical jets.Comment: 35 pages, accepted by the Ap
Proper motions and velocity asymmetries in the RW Aur jet
We present adaptive optics spectro-imaging observations of the RW Aur jet in
optical forbidden lines, at an angular resolution of 0.4 arcsec. Comparison
with HST data taken 2 years later shows that proper motions in the blueshifted
and redshifted lobes are in the same ratio as their radial velocities, a direct
proof that the velocity asymmetry in this jet is real and not an emissivity
effect. The inferred jet inclination to the line of sight is i = 46 +/- 3
degrees. The inner knot spacing appears best explained by time variability with
at least two modes: one irregular and asymmetric (possibly random) on
timescales of <3-10 yr, and another more regular with ~ 20 yr period. We also
report indirect evidence for correlated velocity and excitation gradients in
the redshifted lobe, possibly related to the blue/red velocity and brightness
asymmetry in this system.Comment: 4 pags, 3 figure
Comparative analysis of Klebsiella pneumoniae genomes identifies a phospholipase D family protein as a novel virulence factor
Todas as criaturas do mundo: a arte dos mapas como elemento de orientação geográfica
Vague in the outlines and abounding in figures of real or fabulous creatures, the iconography of medieval maps played a significant role in helping users to recognize lands that were virtually unknown to Christendom. In a world with no reliable latitudes and longitudes, the land contours, inhabitants and even certain elements of fauna and flora could become variables of utmost importance for geographic orientation. Notwithstanding the higher levels of precision achieved in their efforts to represent geographic space, the considerable advancements made in latitude determination, and their continuous pursuit of a practical method for the establishment of longitudes, the cartographers of the Age of Discoveries still went to the trouble of depicting notable elements - whether real or imaginary - to help travelers get their bearings around different regions of the globe. As the presence of Europeans continued to expand and an authentic scientific revolution took place in the 17th century, the lengthy notes and eye¿catching representations of nature and local inhabitants soon lost their utility as points of reference on 17th-century maps to become mere accessories of aesthetic and commercial value. The advent of the 18th century consolidated, once and for all, the transformation of such illustrations into essentially decorative elements with no other relevant role to play in mapmaking. In addition to decreasing in number, the figures became more stylized and moved to the borders of the maps as ornamental motifs. Although they often maintained some sort of relation with the geographic space depicted on the map, the motifs chosen could also constitute a
rather independent element. In fact, allegories, compositions with a variety of mythological figures, and historical representations were often used to underscore the power of certain political agents
Prototipe ‘Penyuluh Agama Buddha' Kajian Linguistik Kognitif: (Prototype of ‘Penyuluh Agama Buddha': A Cognitive Linguistics Study)
Prototype in linguistics field is a mean to determine the level of meaning gradations, where the people have their own concepts, models or views on something. This is a descriptive qualitative research supported by quantitative data. The results show that the most important component of prototype of ‘Penyuluh Agama' is moral according to the concept of sila (morality) as the basis of Buddha's teaching implementation. In addition, the prototype of ‘penyuluh agama Buddha' is based on including two variables, gender, and council.. The two variables have different perspectives and influences on the prototype of ‘penyuluh agama Buddha'. However, most consider the moral component as the most important component. Moreover, the component of the same council is also considered important
ÉTUDE DES EFFETS DES TRAITEMENTS TECHNOLOGIQUES DE L'AMIDON PAR ANALYSE DES CONTENUS DIGESTIFS CHEZ LE PORC
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