3,210 research outputs found
Numerical simulations of the internal shock model in magnetized relativistic jets of blazars
The internal shocks scenario in relativistic jets is used to explain the
variability of the blazar emission. Recent studies have shown that the magnetic
field significantly alters the shell collision dynamics, producing a variety of
spectral energy distributions and light-curves patterns. However, the role
played by magnetization in such emission processes is still not entirely
understood. In this work we numerically solve the magnetohydodynamic evolution
of the magnetized shells collision, and determine the influence of the
magnetization on the observed radiation. Our procedure consists in
systematically varying the shell Lorentz factor, relative velocity, and viewing
angle. The calculations needed to produce the whole broadband spectral energy
distributions and light-curves are computationally expensive, and are achieved
using a high-performance parallel code.Comment: 7 pages, 5 figures, proceeding of the "Swift: 10 Years of Discovery"
conference (December 2014, Rome, Italy
Frobenius pairs in abelian categories: correspondences with cotorsion pairs, exact model categories, and Auslander-Buchweitz contexts
In this work, we revisit Auslander-Buchweitz Approximation Theory and find
some relations with cotorsion pairs and model category structures. From the
notions of relatives generators and cogenerators in Approximation Theory, we
introduce the concept of left Frobenius pairs in an
abelian category . We show how to construct from
a projective exact model structure on
, as a result of Hovey-Gillespie Correspondence applied to
two compatible and complete cotorsion pairs in . These
pairs can be regarded as examples of what we call cotorsion pairs relative to a
thick subcategory of . We establish some correspondences between
Frobenius pairs, relative cotorsion pairs, exact model structures and
Auslander-Buchweitz contexts. Finally, some applications of these results are
given in the context of Gorenstein homological algebra by generalizing some
existing model structures on the categories of modules over Gorenstein and
Ding-Chen rings, and by encoding the stable module category of a ring as a
certain homotopy category. We also present some connections with perfect
cotorsion pairs, covering classes, and cotilting modules.Comment: 54 pages, 10 figures. The statement and proof of 2.6.21 was
corrected. Typos corrected. Section 4 was improved, and new results in
Section 5 were adde
The effect of progesterone in liquid semen extender on fertility and spermatozoa transport in the pig
http://www.worldcat.org/oclc/863595
Numerical study of broadband spectra caused by internal shocks in magnetized relativistic jets of blazars
The internal-shocks scenario in relativistic jets has been used to explain
the variability of blazars' outflow emission. Recent simulations have shown
that the magnetic field alters the dynamics of these shocks producing a whole
zoo of spectral energy density patterns. However, the role played by
magnetization in such high-energy emission is still not entirely understood.
With the aid of \emph{Fermi}'s second LAT AGN catalog, a comparison with
observations in the -ray band was performed, in order to identify the
effects of the magnetic field.Comment: Proceedings of the meeting The Innermost Regions of Relativistic Jets
and Their Magnetic Fields, June 10-14, 2013, Granada (Spain), 4 pages, 3
figure
Homological and homotopical aspects of Gorenstein flat modules and complexes relative to duality pairs
We study homological and homotopical aspects of Gorenstein flat modules over
a ring with respect to a duality pair . These modules are
defined as cycles of exact chain complexes with components in
which remain exact after tensoring by objects in . In the case where
is product closed and bicomplete (meaning in addition that
is closed under extensions, (co)products, ,
is also a duality pair, and is the right half
of a hereditary complete cotorsion pair) we prove that these relative
Gorenstein flat modules are closed under extensions, and that the corresponding
Gorenstein flat dimension is well behaved in the sense that it recovers many of
the properties and characterizations of its (absolute) Gorenstein flat
counterpart (for instance, it can be described in terms of torsion functors).
The latter in turn is a consequence of a Pontryagin duality relation that we
show between these relative Gorenstein flat modules and certain Gorenstein
injective modules relative to . We also find several hereditary
and cofibrantly generated abelian model structures from these Gorenstein flat
modules and complexes relative to . At the level of chain
complexes, we find three recollements between the homotopy categories of these
model structures, along with several derived adjunctions connecting these
recollements.Comment: Some homotopical aspects concerning model structures were added. Some
corrections were made and new examples were include
Magnitude of formative flows in stream potholes
Although it is generally recognized that geomorphic work is tied to bedrock channel reshaping, the importance of low vs. high flow stages that cause the most geomorphic impact remains unclear. The objective of the research is to study the concept of âformative flowâ in bedrock channels and determine, through morphological studies, if those flows have any impact on sculpted features such as potholes and how this relationship relates to various inputs such as flow stages (magnitude and frequency), shear stress, and sediment size. Here, we studied the distribution of the main pothole typologies and tried to understand why potholes are found along bedrock river channels. Specifically, we examined stream potholes from three locations along the Spanish Central System: Alberche, Tietar, and Manzanares rivers. We conducted the research by taking precise geometric measurements, classifying potholes, analyzing flow magnitude and frequency, and using a two-dimensional (2D) hydrodynamic model to assess key variables in Manzanares river. This research demonstrated that bankfull depths completely cover all pothole typologies in all the analyzed sites but are not sufficient to achieve its formative flow depth (FFD). Using a detailed 2D hydrodynamic model in Manzanares river, we discovered that dimensions of cylindrical potholes are closely related to bankfull discharge and that this depth is connected to FFD. Other potholes, such as erosive-compound and erosive-lateral, are historical remnants, and their shapes are not related to any particular FFD and are likely associated with rare events and catastrophic breaks. A collection of laterals that exhibit FFD near bankfull flows appear to represent a part of the recent evolution of a knickpoint. To summarize, it can be inferred from the findings that the utility of morphological analysis in conjunction with the 2D hydrodynamic model is to examine the fraction of erosional/active features to determine the degree of senescence and/or change in natural conditions in a river reach.Depto. de GeodinĂĄmica, EstratigrafĂa y PaleontologĂaFac. de Ciencias GeolĂłgicasTRUERegional Government of Madrid (Spain)pu
Balanced systems for
From the notion of (co)generator in relative homological algebra, we present
the concept of finite balanced system as a tool to induce balanced pairs for the functor with domain determined by the finiteness of
homological dimensions relative to and .
This approach to balance will cover several well known ambients where right
derived functors of are obtained relative to certain classes of
objects in an abelian category, such as Gorenstein projective and injective
modules and chain complexes, Gorenstein modules relative to Auslander and Bass
classes, among others
- âŠ