La formación del concepto de función en alumnos de educación media superior

En este artículo se describe la realización de un taller cuyo diseño responde al marco de una investigación en proceso, que explora los saberes que sobre el concepto de función tienen los alumnos de educación media superior (EMS) y pretende analizar los efectos que presenta la puesta en escena de situaciones didácticas sobre la formación del concepto de función. En la primera etapa de la investigación se están explorando dichos saberes en 30 alumnos de EMS y 10 de los primeros semestres de la licenciatura en matemáticas en Acapulco, Guerrero, México. También se han diseñado situaciones didácticas para abordar este concepto, a fin de que se instrumenten en la escuela. Con estos avances se estructuró el taller para interesados en este campo y realizado en Relme 17 con la participación de siete profesores

Spontaneous Vesicles Modulated by Polymers

Vesicles are widely used in technological applications including cosmetic products, in microencapsulation for drug delivery, as anticancer agents and in the technology of adhesives, paints and inks. The vesicle size and the surface charge are very important properties from a technological point of view. Thus, the challenge in formulation is to find inexpensive stable vesicles with well-defined sizes and to modulate the surface charge of these aggregates. In this work we analyze the effect of different polymers on the structural properties of vesicles of the biodegradable surfactant sodium bis(2-ethyl-hexyl) sulfosuccinate, Aerosol OT. Using fluorescence, conductivity, electrophoretic mobility and dynamic light scattering measurements we study the effect of the polymer nature, molecular weight and polymer concentration on the stability and the vesicle size properties. Results demonstrate that it is possible to modulate both the size and the electric surface charge of spontaneous vesicles of Aerosol OT by the addition of very small percentages of poly(allylamine) and poly(maleic anhydride-alt-1-octadecen)

Kinematics of the H2O masers at the centre of the PN K3-35

We have studied the kinematics traced by the water masers located at the centre of the planetary nebula (PN) K3-35, using data from previous Very Large Array (VLA) observations. An analysis of the spatial distribution and line-of-sight velocities of the maser spots allows us to identify typical patterns of a rotating and expanding ring in the position-velocity diagrams, according to our kinematical model. We find that the distribution of the masers is compatible with tracing a circular ring with a ~0.021 arcsec (~100 AU) radius, observed with an inclination angle with respect to the line of sight of 55 degrees. We derive expansion and rotation velocities of 1.4 and 3.1 km/s, respectively. The orientation of the ring projected on the plane of the sky, at PA 158 degrees, is almost orthogonal to the direction of the innermost region of the jet observed in K3-35, suggesting the presence of a disc or torus that may be related to the collimation of the outflow.Comment: 7 pages, 4 figures, 2 tables. Accepted by MNRA

Discrete Source Survey of 6 GHz OH emission from PNe & pPNe and first 6 GHz images of K 3-35

The aim of this study is to investigate the physical properties of molecular envelopes of planetary nebulae in their earliest stages of evolution. Using the 100m telescope at Effelsberg, we have undertaken a high sensitivity discrete source survey for the first excited state of OH maser emission (J=5/2, 2PI3/2 at 6GHz) in the direction of planetary and proto-planetary nebulae exhibiting 18cm OH emission (main and/or satellite lines), and we further validate our detections using the Nan\c{c}ay radio telescope at 1.6-1.7GHz and MERLIN interferometer at 1.6-1.7 and 6GHz. Two sources have been detected at 6035MHz (5cm), both of them are young (or very young) planetary nebulae. The first one is a confirmation of the detection of a weak 6035MHz line in Vy 2-2. The second one is a new detection, in K 3-35, which was already known to be an exceptional late type star because it exhibits 1720MHz OH emission. The detection of 6035MHz OH maser emission is confirmed by subsequent observations made with the MERLIN interferometer. These lines are very rarely found in evolved stars. The 1612MHz masers surround but are offset from the 1720 and 6035MHz masers which in turn lie close to a compact 22GHz continuum source embedded in the optical nebula.Comment: 9 pages, 7 figures, published in A&

Management Alternatives of Aquifer Storage, Distribution, and Simulation in Conjunctive Use

[EN] Aquifers are ubiquitous, and their water is easy to obtain with low extraction costs. On many occasions, these characteristics lead to overexploitation due to important water level declines, reduction of river base flows, enhanced seawater intrusion, and wetland affection. The forecasted increase in water demands and global warming will impact the future availability of water resources. Conjunctive use of surface and subsurface waters can help in mitigating these impacts. There are two main conjunctive use strategies: artificial recharge (AR) and alternate conjunctive use (ACU). AR stores waters that are not to be used directly in aquifers. ACU utilizes groundwater in dry periods, while surface waters are preferred in wet ones; this allows the increase of water supply with lower dam storage, economic gains, and environmental advantages. Efficient conjunctive use can prevent soil salinization and waterlogging problems in semiarid countries due to excessive recharge from irrigation return flows or other origins. Groundwater is a neglected and generally misused resource to maintain environmental conditions. When considering the solution to a water resources problem, groundwater should always be part of the design as an alternative or a complementary resource. Aquifers have large inertia, and changes in their volumes are only noticeable after years of observations. Unfortunately, groundwater observation networks are much poorer than surface ones, something that should be changed if groundwater is to come to the rescue in these times of climate change. Human and material resources should be made available to monitor, control, analyze, and forecast groundwater.This research was funded by AGREEMAR Project (PCI2022-133001 funded by Spain's MCIN/AEI/10.13039/501100011033, by European Union's NextGenerationEU/PRTR), the SIGLOAN project (RTI2018-101397-B-I00) from the Spanish Ministry of Science, Innovation and Universities (Programa Estatal de I + D + i Orientada a los Retos de la Sociedad) and by project eGROUNDWATER funded by the PRIMA programme supported by the European's Union Horizon 2020 research and innovation programme under grant number 1921.Sahuquillo, A.; Cassiraga, EF.; Gómez-Hernández, JJ.; Andreu Álvarez, J.; Pulido-Velazquez, M.; Pulido Velázquez, D.; Álvarez-Villa, ÓD.... (2022). Management Alternatives of Aquifer Storage, Distribution, and Simulation in Conjunctive Use. Water. 14(15):1-15. https://doi.org/10.3390/w14152332115141

Periodontal Disease and Nuclear and Oxidative DNA Damage

Oral health is an important aspect of the overall health status of an individual. DNA damage has been associated with oral health and dental factors due to the increased of oxidative stress (OxS). DNA damage can produce a wide range of effects on human health. These effects could appear immediately, but others do not become evident much later. Chronic diseases have been study to understand their mechanisms, clinical implications, and the development of secondary disease such as cancer. Periodontitis is one of the most common oral diseases. It is an inflammatory chronic infectious disease, which is characterized by the loss of supporting tissues and tooth loss caused by periodontopathogens and long-term release of reactive oxygen species (ROS); thus, oxidative stress is increased during periodontitis. Oxidative stress can produce DNA damage, including the oxidation of nucleosides, which could cause DNA strand break. This oxidative damage leads the formation of micronuclei (MN) a marker of nuclear damage. Also, oxidative stress increased 8-hydroxy-2′-deoxyguanosine levels which are the most common stable product of oxidative DNA damage

HAp Nanofibers Grown with Crystalline Preferential Orientation and Its Influence in Mechanical Properties of Organic-Inorganic Composite Materials

There are several synthesis techniques to obtain hydroxyapatite (HAp). Some use surfactant agents, amino acids or halogen salts to control structural nucleation and crystal growth. In others, the use of hydrothermal process to carry out the reaction is effective for HAp synthesis. Microwave-assisted hydrothermal method (MAHM) has been successfully applied in the synthesis of HAp nanostructures, which present well-defined morphologies, high crystallinity and high purity. This is important because nano-HAp is attracting interest as a biomaterial for use in prosthetic applications due to its similarity in size, crystallinity and chemical composition with human hard tissue. In this chapter, developments in obtaining HAp nanofibers, with a crystal growth with preferential orientation, as well as morphology control achieved by using the MAHM is discussed. Also, the synthesized fibers were used to cast ceramics with controlled and interconnected porosity through the modified gelcasting process. Then, these HAp ceramics were impregnated with a water solution of gelatin in order to obtain an organic-inorganic composite material, similar to natural bone tissue. The maximum compressive strengths were determined and the composite materials showed mechanical properties that make them suitable to be used as bone tissue implants

On the interaction of microquasar jets with stellar winds

Strong interactions between jets and stellar winds at binary system spatial scales could occur in high-mass microquasars. We study here, mainly from a dynamical but also a radiative point of view, the collision between a dense stellar wind and a mildly relativistic hydrodynamical jet of supersonic nature.}{We have performed numerical 2-dimensional simulations of jets, with cylindrical and planar (slab) symmetry, crossing the stellar wind material. From the results of the simulations, we derive estimates of the particle acceleration efficiency, using first order Fermi acceleration theory, and give some insight on the possible radiative outcomes. We find that, during jet launching, the jet head generates a strong shock in the wind. During and after this process, strong recollimation shocks can occur due to the initial overpressure of the jet with its environment. The conditions in all these shocks are convenient to accelerate particles up to $\sim$ TeV energies, which can lead to leptonic (synchrotron and inverse Compton) and hadronic (proton-proton) radiation. In principle, the cylindrical jet simulations show that the jet is stable, and can escape from the system even for relatively low power. However, when accounting for the wind ram pressure, the jet can be bent and disrupted for power \la 10^{36} erg s$^{-1}$.Comment: Accepted for publication in Astronomy & Astrophysic

Revisiting 2D Numerical Models for the 19th century outbursts of η\eta Carinae

We present here new results of two-dimensional hydrodynamical simulations of the eruptive events of the 1840s (the great) and the 1890s (the minor) eruptions suffered by the massive star $\eta$ Car. The two bipolar nebulae commonly known as the Homunculus and the little Homunculus were formed from the interaction of these eruptive events with the underlying stellar wind. As in previous work (Gonzalez et al. 2004a, 2004b), we assume here an interacting, nonspherical multiple-phase wind scenario to explain the shape and the kinematics of both Homunculi, but adopt a more realistic parametrization of the phases of the wind. During the 1890s eruptive event, the outflow speed {\it decreased} for a short period of time. This fact suggests that the little Homunculus is formed when the eruption ends, from the impact of the post-outburst $\eta$ Car wind (that follows the 1890s event) with the eruptive flow (rather than by the collision of the eruptive flow with the pre-outburst wind, as claimed in previous models; Gonzalez et al. 2004a, 2004b). Our simulations reproduce quite well the shape and the observed expansion speed of the large Homunculus. The little Homunculus (which is embedded within the large Homunculus) becomes Rayleigh-Taylor unstable and develop filamentary structures that resembles the spatial features observed in the polar caps. In addition, we find that the interior cavity between the two Homunculi is partially filled by material that is expelled during the decades following the great eruption. This result may be connected with the observed double-shell structure in the polar lobes of the $\eta$ Car nebula. Finally, as in previous work, we find the formation of tenuous, equatorial, high-speed features that seem to be related to the observed equatorial skirt of $\eta$ Car.Comment: accepted for publication in MNRA