5,650 research outputs found
Hybrid algorithm with perturbations for total asymptotically non-expansive mappings in CAT(0) space
In this paper, we establish strong and Δ-convergence theorems of the modified hybrid-CR three steps iteration with perturbations for total asymptotically non-expansive mapping in CAT(0) spaces. Our results improve and extend the corresponding results from the current literature. We also provide three examples to illustrate the convergence behaviour of the proposed algorithm and numerically compare the convergence of the proposed iteration scheme with the existing schemes
Development of type 2 diabetes mellitus thirty-one years after Billroth II in a patient asking for diabetes surgery
Introduction: Diabetes surgery in obese and slim patients seems to be a superior alternative to the current medical treatment. Gastric bypass is an alternative treat- ment for diabetes. Nevertheless, there are still doubts whether diabetes can recur if you gain weight or if the effects are maintained over time. Other questions refer to the type of surgery to make the bypass limb length or reservoir size for the resolution of the Diabetes Mellitus. Presentation of case: Male patient 69-year-old came to us in order to perform tailored One Anastomosis Gastric Bypass (BAGUA) to treat his type 2 diabetes mellitus and metabolic syndrome. He has a history of peptic ulcer treated with subtotal gastrectomy and Billroth II recons- truction 49 years ago. He currently is not obese and deve- loped diabetes 31 years after surgery. Discussion: Globally there are no reports of patients with normal BMI that after performing gastric bypass developed diabetes mellitus. There are cases where obese diabetic patients after gastric bypass improve or remits the T2DM, but it relapses due to insufficient weight loss or gain it. The patient with gastric bypass Billroth II type, should not developed diabetes. He is normal weight and not had weight gain that could be linked to the develop- ment of diabetes. Conclusions: The results generated by bariatric surgery are encouraging, but still do not clarify the precise way how surgery produces rapid improvement of systemic metabolism as in diabetes, but in our patient, the effect was quite different because the gastric bypass had no protective effect against diabetes
Polar coherent states in bilayer graphene under a constant uniform magnetic field
Symmetries associated with the Hamiltonian describing bilayer graphene
subjected to a constant magnetic field perpendicular to the plane of the
bilayer are calculated using polar coordinates. These symmetries are then
applied to explain some fundamental properties, such as the spectrum and the
integer pseudo-spin character of the eigenfunctions. The probability and
current densities of the bilayer Hamiltonian have also been calculated in polar
coordinates and shown to be gauge invariant and scalar under generalized
rotations. We also define appropriate coherent states of this system as
eigenfunctions, with complex eigenvalues, of a suitable chose annihilation
operator. In this framework, symmetries are also useful to show the meaning of
the complex eigenvalue in terms of expected values. The local current density
of these coherent states is shown to exhibit a kind of radial component
interference effect, something that has gone unnoticed until now. Some of these
results that have just been exposed are graphically illustrated throughout the
manuscript
Evaluación del dispositivo Pavement Quality Indicator (PQI) en la determinación de la densidad in situ de mezclas fabricadas con emulsión bituminosa
The Pavement Quality Indicator (PQI) is a non-nuclear gauge used for the on-site density measurement of asphalt pavements without the need to extract core samples. Previous studies of hot asphalt mixes found that PQI density readings were very similar to laboratory density measurements of pavement cores. This paper describes the first stage of a research project whose objective is to analyze PQI density measurements of mixes manufactured with an asphalt emulsion binder. The PQI density variability for such mixes was verified and compared with the results obtained with other on-site methods for measuring pavement density.El equipo Pavement Quality Indicator es un dispositivo para la determinación de densidad in situ en pavimentos asfálticos sin extracción de testigos. Las experiencias con este equipo en mezclas bituminosas en caliente, recogidas en diferentes fuentes bibliográficas, muestran que las densidades medidas in situ con el PQI son muy similares a las obtenidas mediante la extracción de testigos. En este artículo se expone la primera etapa de un proyecto de investigación que tiene por objeto analizar los resultados de mediciones efectuadas con PQI en mezclas bituminosas donde se utiliza emulsión asfáltica como ligante. Se comprueba la variabilidad de la densidad obtenida con el equipo para este tipo de mezclas, y se comparan los resultados con otros métodos de medida de densidad in situ
Supersymmetry and superalgebra for the two-body system with a Dirac oscillator interaction
Some years ago, one of the authors~(MM) revived a concept to which he gave
the name of single-particle Dirac oscillator, while another~(CQ) showed that it
corresponds to a realization of supersymmetric quantum mechanics. The Dirac
oscillator in its one- and many-body versions has had a great number of
applications. Recently, it included the analytic expression for the eigenstates
and eigenvalues of a two-particle system with a new type of Dirac oscillator
interaction of frequency~. By considering the latter together with its
partner corresponding to the replacement of~ by~, we are able
to get a supersymmetric formulation of the problem and find the superalgebra
that explains its degeneracy.Comment: 21 pages, LaTeX, 1 figure (can be obtained from the authors), to
appear in J. Phys.
The Pursuit of External Knowledge in Eco-Innovation. Analysis of the Agri-Food Sector in Spain
The research about the search for opportunities through open cooperation strategies points to an exchange of knowledge among a certain number of sources, aimed at sustaining competitive advantage. From this new vision emerges the paradigm of open innovation, which has prompted a change in the organization of resources, information filtering, and rapid absorptive capacity. Awareness of climate problems and external societal pressures can motivate companies to create new technologies and new forms of cooperation to avoid environmental problems. Based on a survey of Spanish agri-food firms, we find that the depth of external sources of innovation increases environmental improvement in a U-shaped relationship
Ambipolar diffusion in the Bifrost code
Ambipolar diffusion is a physical mechanism related to the drift between
charged and neutral particles in a partially ionized plasma that is key in many
different astrophysical systems. However, understanding its effects is
challenging due to basic uncertainties concerning relevant microphysical
aspects and the strong constraints it imposes on the numerical modeling. Our
aim is to introduce a numerical tool that allows us to address complex problems
involving ambipolar diffusion in which, additionally, departures from
ionization equilibrium are important or high resolution is needed. The primary
application of this tool is for solar atmosphere calculations, but the methods
and results presented here may also have a potential impact on other
astrophysical systems. We have developed a new module for the stellar
atmosphere Bifrost code that improves its computational capabilities of the
ambipolar diffusion term in the Generalized Ohm's Law. This module includes,
among other things, collision terms adequate to processes in the coolest
regions in the solar chromosphere. As a key feature of the module, we have
implemented the Super Time-Stepping (STS) technique, that allows an important
acceleration of the calculations. We have also introduced hyperdiffusion terms
to guarantee the stability of the code. We show that to have an accurate value
for the ambipolar diffusion coefficient in the solar atmosphere it is necessary
to include as atomic elements in the equation of state not only hydrogen and
helium but also the main electron donors like sodium, silicon and potassium. In
addition, we establish a range of criteria to set up an automatic selection of
the free parameters of the STS method that guarantees the best performance,
optimizing the stability and speed for the ambipolar diffusion calculations. We
validate the STS implementation by comparison with a self-similar analytical
solution.Comment: Accepted in A&A, 10 pages, 7 figure
On the removal of s-triazine herbicides from waters using commercial low-cost granular carbons
The adsorption capacities of three low-cost granular active carbons, used in a water treatment facility for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that the three carbon samples used could be suitable in practice for the treatment of moderate contents of the herbicides in contaminated waters. The apparent adsorption rate constants were calculated. Equilibrium studies showed that the data fit the Frumkin isotherm. The results show that in the adsorption process there are repulsive lateral interactions that depend mainly on the adsorbate molecules rather than the nature or distribution of the adsorption sites. Such lateral interactions seem to be established mainly between the isopropyl groups of adjacent molecules, being of the same order for the three molecules
Ac magnetic susceptibility of a molecular magnet submonolayer directly patterned onto a microSQUID sensor
We report the controlled integration, via Dip Pen Nanolithography, of
monolayer dots of ferritin-based CoO nanoparticles (12 Bohr magnetons) into the
most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling
between these nanomagnets and the microSQUID improves the achievable
sensitivity by a factor 100, enabling us to measure the linear susceptibility
of the molecular array down to very low temperatures (13 mK). This method opens
the possibility of applying ac susceptibility experiments to characterize
two-dimensional arrays of single molecule magnets within a wide range of
temperatures and frequencies.Comment: 4 pages 3 figure
Solar Flux Emergence Simulations
We simulate the rise through the upper convection zone and emergence through
the solar surface of initially uniform, untwisted, horizontal magnetic flux
with the same entropy as the non-magnetic plasma that is advected into a domain
48 Mm wide from from 20 Mm deep. The magnetic field is advected upward by the
diverging upflows and pulled down in the downdrafts, which produces a hierarchy
of loop like structures of increasingly smaller scale as the surface is
approached. There are significant differences between the behavior of fields of
10 kG and 20 or 40 kG strength at 20 Mm depth. The 10 kG fields have little
effect on the convective flows and show little magnetic buoyancy effects,
reaching the surface in the typical fluid rise time from 20 Mm depth of 32
hours. 20 and 40 kG fields significantly modify the convective flows, leading
to long thin cells of ascending fluid aligned with the magnetic field and their
magnetic buoyancy makes them rise to the surface faster than the fluid rise
time. The 20 kG field produces a large scale magnetic loop that as it emerges
through the surface leads to the formation of a bipolar pore-like structure.Comment: Solar Physics (in press), 12 pages, 13 figur
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