9,789 research outputs found
Creating agent platforms to host agent-mediated services that share resources
After a period where the Internet was exclusively filled with content,
the present
efforts are moving towards services, which handle the raw information to
create
value from it. Therefore labors to create a wide collection of
agent-based services
are being perfomed in several projects, such as Agentcities does.
In this work we present an architecture for agent platforms named
a-Buildings. The
aim of the proposed architecture is to ease the creation, installation,
search and
management of agent-mediated services and the share of resources among
services.
To do so the a-Buildings architecture creates a new level of abstraction
on top of
the standard FIPA agent platform specification.
Basically, an a-Building is a service-oriented platform which offers a
set of
low level services to the agents it hosts. We define low level services
as those
required services that are neccesary to create more complex high level
composed
services.Postprint (published version
Exponential Convergence Towards Stationary States for the 1D Porous Medium Equation with Fractional Pressure
We analyse the asymptotic behaviour of solutions to the one dimensional
fractional version of the porous medium equation introduced by Caffarelli and
V\'azquez, where the pressure is obtained as a Riesz potential associated to
the density. We take advantage of the displacement convexity of the Riesz
potential in one dimension to show a functional inequality involving the
entropy, entropy dissipation, and the Euclidean transport distance. An argument
by approximation shows that this functional inequality is enough to deduce the
exponential convergence of solutions in self-similar variables to the unique
steady states
Investigation of the Nicole model
We study soliton solutions of the Nicole model - a non-linear
four-dimensional field theory consisting of the CP^1 Lagrangian density to the
non-integer power 3/2 - using an ansatz within toroidal coordinates, which is
indicated by the conformal symmetry of the static equations of motion. We
calculate the soliton energies numerically and find that they grow linearly
with the topological charge (Hopf index). Further we prove this behaviour to
hold exactly for the ansatz. On the other hand, for the full three-dimensional
system without symmetry reduction we prove a sub-linear upper bound,
analogously to the case of the Faddeev-Niemi model. It follows that symmetric
solitons cannot be true minimizers of the energy for sufficiently large Hopf
index, again in analogy to the Faddeev-Niemi model.Comment: Latex, 35 pages, 1 figur
Evaluation of Bacterial Resistance to Antibiotics in Stool Samples Obtained from Guinea Pigs (Cavia porcellus) in Family and Family-commercial Farms
The inappropriate use of antimicrobial agents in guinea pigs to control enteric pathogens affects the nutritional sustainability of the rural population. Therefore, it is important to identify the pathogen, its resistance, and the appropriate antimicrobial agent for its control. The present investigation was carried out in family and family-commercial guinea pig farms, in eight rural parishes of the Gualaceo canton, Azuay province, Ecuador, from which 384 samples were obtained by rectal swabbing of guinea pigs from production units with enteric problems (diarrhea), the same ones that were transferred to the laboratory of the Faculty of Agricultural Sciences of the University of Cuenca, in order to identify the bacterial agents present in fecal samples of guinea pigs. There the isolation of culture media and identification of pathogens were carried out, they were subsequently exposed to an antibiogram, in order to qualitatively assess their bacterial resistance. The data were tabulated and analyzed in SPSS, finding the presence of Escherichia coli (49.4%), Salmonella typhimurium (24.6%), Shigella flexneri (14.3%), and Klebsiella pneumoniae (11.7%). The Chi-square test determined that of the five antimicrobials used, only tetracycline had a relationship between bacterial presence and resistance. It was also found that Escherichia coli presented a higher percentage of resistance, for enrofloxacin 22.5%, neomycin 14.2%, sulfamethoxazole - trimethoprim 33.3%, tetracyclines 29.2%. Data were analyzed at a confidence level of 95% with a 5% error, concluding that the identified pathogens have low resistance to the antimicrobials used, but are still susceptible.
Keywords: bacterial resistance, antibiogram, enteric infection, antibiotics.
Resumen
El uso inadecuado de agentes antimicrobianos en cobayos para controlar patógenos entéricos, afectan la sustentabilidad alimenticia de la población rural, por ello es importante identificar el patógeno, su resistencia y el agente antimicrobiano adecuado para su control. La presente investigación se realizó en explotaciones de cobayos de tipo familiar y familiar – comercial, en ocho parroquias rurales del cantón Gualaceo provincia del Azuay, Ecuador de donde se obtuvo 384 muestras mediante hisopado rectal de cobayos provenientes de unidades productoras con problemas entéricos (diarrea), las mismas que fueron trasladadas al laboratorio de la Facultad de Ciencias Agropecuarias de la Universidad de Cuenca, con el fin de identificar los agentes bacterianos presentes en muestras fecales de cobayos, ahà se realizó la infección de medios de cultivo e identificación de agentes patógenos, mismos que posteriormente fueron expuestos a un antibiograma, con la finalidad de evaluar cualitativamente su resistencia bacteriana. Los datos fueron tabulados y analizados en SPSS, encontrándose la presencia de Escherichia coli (49,4%), Salmonella typhimurium (24,6%), Shigella flexneri (14,3%) y Klebsiella pneumoniae (11,7%). En la prueba de chi 2, se determinó que de los cinco antimicrobianos usados, solamente la Tetraciclina tiene relación entre la presencia bacteriana y la resistencia; también se encontró que Escherichia coli presentó mayor porcentaje de resistencia, para Enrofloxacina 22,5%, Neomicina 14,2%, Sulfametoxazol – trimetoprim 33,3%, Tetraciclinas 29,2%, datos que fueron analizados a un nivel de confianza del 95% con un 5% de error, concluyendo que los patógenos identificados presentan baja resistencia a los antimicrobianos utilizados, pero aún son susceptibles.
Palabras Clave: resistencia bacteriana, antibiograma, infección entérica, antibióticos
Strongly-Coupled Quarks and Colorful Black Holes
We use the AdS/CFT correspondence to study the behavior of strongly-coupled
quarks in a black hole background. The supergravity background consists of a
six-dimensional Schwarzschild-black string AdS soliton, for which the bulk
horizon extends from the AdS boundary down to an infra-red floor. By going to
higher energy scales, the regime of validity of the classical supergravity
background can be extended closer to the singularity than might be expected
from the four-dimensional perspective. Small black holes potentially created by
the Large Hadron Collider could typically carry color charges inherited from
their parton progenitors. The dynamics of quarks near such a black hole depends
on the curved spacetime geometry as well as the strong interaction with the
color-charged black hole. We study the resulting behavior of quarks and compute
the rate at which a quark rotating around the black hole loses energy. We also
investigate how the interaction between a quark and an antiquark is altered by
the presence of the black hole, which results in a screening length.Comment: Proceedings of the DPF-2011 Conference, 8 pages, 5 figures, added
reference
Three-dimensional numerical simulation of 1GeV/Nucleon U92+ impact against atomic hydrogen
The impact of 1GeV/Nucleon U92+ projectiles against atomic hydrogen is
studied by direct numerical resolution of the time-dependent wave equation for
the atomic electron on a three-dimensional Cartesian lattice. We employ the
fully relativistic expressions to describe the electromagnetic fields created
by the incident ion. The wave equation for the atom interacting with the
projectile is carefully derived from the time-dependent Dirac equation in order
to retain all the relevant terms.Comment: 12 pages and 7 figures included in the tex
Examples of signature (2,2) manifolds with commuting curvature operators
We exhibit Walker manifolds of signature (2,2) with various commutativity
properties for the Ricci operator, the skew-symmetric curvature operator, and
the Jacobi operator. If the Walker metric is a Riemannian extension of an
underlying affine structure A, these properties are related to the Ricci tensor
of A
Finite elements numerical solution of a coupled profile–velocity–temperature shallow ice sheet approximation model
AbstractThis work deals with the numerical solution of a complex mathematical model arising in theoretical glaciology. The global moving boundary problem governs thermomechanical processes jointly with ice sheet hydrodynamics. One major novelty is the inclusion of the ice velocity field computation in the framework of the shallow ice model so that it can be coupled with profile and temperature equations. Moreover, the proposed basal velocity and shear stress laws allow the integration of basal sliding effects in the global model. Both features were not taking into account in a previous paper (Math. Model. Methods Appl. Sci. 12 (2) (2002) 229) and provide more realistic convective terms and more complete Signorini boundary conditions for the thermal problem. In the proposed numerical algorithm, one- and two-dimensional piecewise linear Lagrange finite elements in space and a semi-implicit upwinding scheme in time are combined with duality and Newton's methods for nonlinearities. A simulation example involving real data issued from Antarctic shows the temperature, profile and velocity qualitative behaviour as well as the free boundaries and basal effects
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