21,529 research outputs found
Science with the World Space Observatory - Ultraviolet
The World Space Observatory-Ultraviolet (WSO-UV) will provide access to the
UV range during the next decade. The instrumentation on board will allow to
carry out high resolution imaging, high sensitivity imaging, high resolution
(R~55000) spectroscopy and low resolution (R~2500) long slit spectroscopy. In
this contribution, we briefly outline some of the key science issues that
WSO-UV will address during its lifetime. Among them, of special interest are:
the study of galaxy formation and the intergalactic medium; the astronomical
engines; the Milky Way formation and evol ution, and the formation of the Solar
System and the atmospheres of extrasolar p lanets.Comment: Just one text file (aigomezdecastro.tex). To be published in the
proceeding of the conference: "New Quest in Stellar Astrophysics II: UV
properties of evolved stellar populations" held in Puerto Vallarta - Mexico,
in april 200
Noncommutative associative superproduct for general supersymplectic forms
We define a noncommutative and nonanticommutative associative product for
general supersymplectic forms, allowing the explicit treatment of
non(anti)commutative field theories from general nonconstant string backgrounds
like a graviphoton field. We propose a generalization of deformation
quantization a la Fedosov to superspace, which considers noncommutativity in
the tangent bundle instead of base space, by defining the Weyl super product of
elements of Weyl super algebra bundles. Super Poincare symmetry is not broken
and chirality seems not to be compromised in our formulation. We show that, for
a particular case, the projection of the Weyl super product to the base space
gives rise the Moyal product for non(anti)commutative theories.Comment: 22 pages, revtex4. References added. Comments added. Includes
additional theorem proof
Ambipolar Filamentation of Turbulent Magnetic Fields : A numerical simulation
We present the results of a 2-D, two fluid (ions and neutrals) simulation of
the ambipolar filamentation process, in which a magnetized, weakly ionized
plasma is stirred by turbulence in the ambipolar frequency range. The higher
turbulent velocity of the neutrals in the most ionized regions gives rise to a
non-linear force driving them out of these regions, so that the initial
ionization inhomogeneities are strongly amplified. This effect, the ambipolar
filamentation, causes the ions and the magnetic flux to condense and separate
from the neutrals, resulting in a filamentary structure.Comment: 8 pages, 6 figures, accepted for publication in A&
Super Five Brane Hamiltonian and the Chiral Degrees of Freedom
We construct the Hamiltonian of the super five brane in terms of its physical
degrees of freedom. It does not depend on the inverse of the induced metric.
Consequently, some singular configurations are physically admissible, implying
an interpretation of the theory as a multiparticle one. The symmetries of the
theory are analyzed from the canonical point of view in terms of the first and
second class constraints. In particular it is shown how the chiral sector may
be canonically reduced to its physical degrees of freedom.Comment: 16 pages, typos correcte
A novel programmable lysozyme-based lysis system in Pseudomonas putida for biopolymer production
Indexación: Scopus; Web of Science.Cell lysis is crucial for the microbial production of industrial fatty acids, proteins, biofuels, and biopolymers. In this work, we developed a novel programmable lysis system based on the heterologous expression of lysozyme. The inducible lytic system was tested in two Gram-negative bacterial strains, namely Escherichia coli and Pseudomonas putida KT2440. Before induction, the lytic system did not significantly arrest essential physiological parameters in the recombinant E. coli (ECPi) and P. putida (JBOi) strain such as specific growth rate and biomass yield under standard growth conditions. A different scenario was observed in the recombinant JBOi strain when subjected to PHA-producing conditions, where biomass production was reduced by 25% but the mcl-PHA content was maintained at about 30% of the cell dry weight. Importantly, the genetic construct worked well under PHA-producing conditions (nitrogen-limiting phase), where more than 95% of the cell population presented membrane disruption 16 h post induction, with 75% of the total synthesized biopolymer recovered at the end of the fermentation period. In conclusion, this new lysis system circumvents traditional, costly mechanical and enzymatic cell-disrupting procedures.https://www.nature.com/articles/s41598-017-04741-2.pd
Aspectos biológicos de Ungla ivancruzi (Neuroptera: chrysopidae) alimentada com Schizaphis graminum (Rondani) (Hemiptera: aphididae).
On the Interacting Chiral Gauge Field Theory in D=6 and the Off-Shell Equivalence of Dual Born-Infeld-Like Actions
A canonical action describing the interaction of chiral gauge fields in D=6
Minkowski space-time is constructed. In a particular partial gauge fixing it
reduces to the action found by Perry and Schwarz. The additional gauge
symmetries are used to show the off-shell equivalence of the dimensional
reduction to D=5 Minkowski space-time of the chiral gauge field canonical
action and the Born-Infeld canonical action describing an interacting D=5
Abelian vector field. Its extension to improve the on-shell equivalence
arguments of dual D-brane actions to off-shell ones is discussed.Comment: 18 page
Formation of X-ray emitting stationary shocks in magnetized protostellar jets
X-ray observations of protostellar jets show evidence of strong shocks
heating the plasma up to temperatures of a few million degrees. In some cases,
the shocked features appear to be stationary. They are interpreted as shock
diamonds. We aim at investigating the physics that guides the formation of
X-ray emitting stationary shocks in protostellar jets, the role of the magnetic
field in determining the location, stability, and detectability in X-rays of
these shocks, and the physical properties of the shocked plasma. We performed a
set of 2.5-dimensional magnetohydrodynamic numerical simulations modelling
supersonic jets ramming into a magnetized medium and explored different
configurations of the magnetic field. The model takes into account the most
relevant physical effects, namely thermal conduction and radiative losses. We
compared the model results with observations, via the emission measure and the
X-ray luminosity synthesized from the simulations. Our model explains the
formation of X-ray emitting stationary shocks in a natural way. The magnetic
field collimates the plasma at the base of the jet and forms there a magnetic
nozzle. After an initial transient, the nozzle leads to the formation of a
shock diamond at its exit which is stationary over the time covered by the
simulations (~ 40 - 60 yr; comparable with time scales of the observations).
The shock generates a point-like X-ray source located close to the base of the
jet with luminosity comparable with that inferred from X-ray observations of
protostellar jets. For the range of parameters explored, the evolution of the
post-shock plasma is dominated by the radiative cooling, whereas the thermal
conduction slightly affects the structure of the shock.Comment: Accepted for publication in Astronomy and Astrophysic
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