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Patrones temporales en la interacción entre hormigas y Cylindropuntia imbricata: la relevancia de los nectarios extraflorales
Get PDF"La presente investigación tiene como objetivo evaluar el efecto del periodo (diurno
y nocturno) y de tres etapas del período de lluvias (inicio, mitad y final) en la
estructura de la interacción hormigas - Cylindropuntia imbricata, así como analizar
morfológica y anatómicamente el desarrollo de los nectarios extraflorales (NEF) en
las tres etapas del período de lluvias. El sitio de estudio se encuentra en la localidad
San Juanico El Chico, municipio de San Luis Potosí, S.L.P., donde se seleccionaron
diez plantas de 1.5 m y se monitorearon la abundancia de hormigas en los tres
segmentos superiores de la misma, durante toda la temporada. Se encontró una
dominancia por parte de la especie de hormiga Liometopum apiculatum como
visitante de los nectarios extraflorales de C. imbricata, tanto en el día como en la
noche, aumentando su actividad en el periodo nocturno. La abundancia total de
hormigas mostró la misma tendencia, pero esta diferencia disminuyó en la etapa
final del periodo de lluvias, asociándose negativamente a las bajas temperaturas y
a la alta humedad relativa. Los NEF comenzaron a contraerse en sus ápices a partir
de la mitad del periodo de lluvias, hasta formar pequeñas estructuras lignificadas;
hacia el final del periodo de lluvias se observaron espinas modificadas en su
totalidad. Los patrones temporales de los ecosistemas son tan importantes en las
interacciones planta-hormiga que marcan los ritmos de acción en la actividad
forrajera de las hormigas, así como en el desarrollo anatómico y morfológico de los
nectarios extraflorales de C. imbricata.""The aim of this research is to evaluate the effect of time (day and night) and three
stages of the rainy season (beginning, middle and end) in the structure of the
interaction ants - Cylindropuntia imbricata, as well as to analyze morphological and
anatomical development of extra-floral nectaries at different stages of the rainy
season. The study site is located in the town San Juanico El Chico, municipality of
San Luis Potosi, S.L.P. where ten plants of 1.5 m were selected and the abundance
of ants in the three upper segments of the same was monitored throughout the
season. The ant Liometopum apiculatum was the most abundant visitor of the extrafloral
nectaries from C. imbricata, both at day and night, increasing their activity in
the night time. The total abundance of ants showed the same behaviour, but
decreased at the end of the rainy season, being associated negatively to low
temperatures and high relative humidity. The extra-floral nectaries (EFN) began to
shrink in their apexes from the half of the rainfall period until form small lignified
structures; towards the end of this period the spines were entirely modified.
Temporal patterns of ecosystems are so important in the ant-plant interactions that
mark the rhythms of action in the foraging activity, as well as the anatomical and
morphological development of the C. imbricata´s EFN.
Two P2X1 receptor transcripts able to form functional channels are present in most human monocytes
Get PDF"To characterize the presence and general properties of P2X1 receptors in single human monocytes we used RT-PCR, flow cytometry, and the patch-clamp and the two-electrode voltage-clamp techniques. Most human monocytes expressed the canonical P2X1 (90%) and its splicing variant P2X1del (88%) mRNAs. P2X1 receptor immunoreactivity was also observed in 70% of these cells. Currents mediated by P2X1 (EC50=1.9±0.8 µm) and P2X1del (EC50 >1000 µm) channels, expressed in Xenopus leavis oocytes, have different ATP sensitivity and kinetics. Both currents mediated by P2X1 and P2X1del channels kept increasing during the continuous presence of high ATP concentrations. Currents mediated by the native P2X1 receptors in human monocytes showed an EC50=6.3±0.2 µm. Currents have kinetics that resemble those observed for P2X1 and P2X1del receptors in oocytes. Our study is the first to demonstrate the expression of P2X1 transcript and its splicing variant P2X1del in most human monocytes. We also, for the first time, described functional homomeric P2X1del channels and demonstrated that currents mediated by P2X1 or P2X1del receptors, during heterologous expression, increased in amplitude when activated with high ATP concentrations in a similar fashion to those channels that increase their conductance under similar conditions, such as P2X7, P2X2, and P2X4 channels.
Análisis inmunológico de epítopos relevantes del virus sincicial respiratorio producidos en plantas
Get PDF"Las enfermedades infecciosas respiratorias, representan un área importante en el
desarrollo de vacunas, debido a los altos costos de hospitalización que generan. El
virus sincicial respiratorio (VSR) es el principal patógeno de estas enfermedades en
niños y uno de los principales en ancianos. Aunque el VSR se ha estudiado por más
de 40 años, no hay una vacuna eficaz contra él. La tendencia actual para el
desarrollo de vacunas acelulares es su producción por métodos recombinantes. Una
alternativa para la producción de proteínas recombinantes de valor farmacéutico es
su expresión en plantas y los polipéptidos antigénicos son un sistema atractivo para
la producción de vacunas. El presente trabajo se centra en la expresión de
polipéptidos antigénicos con epítopos relevantes del VSR en plantas como un primer
paso para el desarrollo de una vacuna comestible. Las proteínas F y G de la
envoltura del VSR podrían ser blancos para el desarrollo de vacunas. Se
construyeron vectores con secuencias para epítopos relevantes codificados por los
genes F y G del VSR y con ellos se la transformaron plantas de lechuga y
cloroplastos de tabaco. Los genes sintéticos, optimizados para su expresión en
plantas, codifican tres epítopos de la proteína F y un epítopo de la proteína G de
VSR unidos por espaciadores. Se transformó lechuga con Agrobacterium
tumefaciens y cloroplastos de tabaco por biobalística. El transgén se detectó por
PCR y Southern blot; la proteína heteróloga por SDS-PAGE y la antigenicidad de
ésta mediante ELISA y Western blot. Finalmente se realizaron análisis
inmunogénicos en ratones Balb/c; grupos de cinco ratones fueron inmunizados con
lechuga transgénica, lechuga silvestre y una suspensión de proteínas purificadas de
VSR (Serotec). El grupo de lechuga transgénica mostró niveles más altos de
seroanticuerpos IgG que el grupo de lechuga silvestre. Este trabajo es un primer
paso hacia la generación de una vacuna comestible en sistemas vegetales contra
VSR que contiene epítopos de las proteínas F y G.""Infectious respiratory diseases are an important area for the vaccine development
due to the high cost of hospitalization that they generate. Respiratory syncytial virus
(RSV) is the most important respiratory pathogen leading to hospitalizations in young
children but is also important in elderly people. Although RSV has been investigated
for more than 40 years, an effective vaccine is not yet available. The current trend for
the development of acellular vaccines is produced by recombinant methods.
Recently, plants are being exploited to express recombinant proteins of
pharmaceutical value; plant-based vaccines present an attractive system for the
production of antigenic peptides. The current work focused on the expression of
antigenic peptides derived from RSV in plants as a first step for the development of
an edible vaccine. F and G proteins of the envelope of VSR could be targets for the
development of vaccines. We designed vectors for transformation of lettuce plant and
tobacco plastids, harboring sequences for relevant epitopes encoded by the F and G
genes of RSV. The synthetic genes, optimized in the codon-usage bias for their
expression in plants encode three epitopes from the F protein and one epitope from
the G protein fused by linkers. The lettuce transformation was achieved by cocultivation
with Agrobacterium tumefaciens and tobacco plastids by biobalistics. The
presence of the transgene was demonstrated by PCR and Southern blot analysis,
and production of the heterologous protein by SDS-PAGE, in addition the antigenicity
of the latter was demonstrated by ELISA and Western blot. Finally we performed
immunogenic analysis in Balb/c mice; three groups of five female mice were
immunized with transgenic lettuce, wild type lettuce and a suspension of purified
proteins from RSV (AbD Serotec). The transgenic lettuce group showed higher IgG
antibodies levels than the wild type lettuce group. This work is a first step towards the
generation of an edible vaccine in plant systems against RSV harboring epitopes from
F and G proteins.
Absence of evidence is not evidence of absence: Multiple steady states in ammonia synthesis
Get PDF"Using a chemical reaction network (CRN) Theory approach, three well-accepted mechanisms of ammonia synthesis over iron catalyst taking place within an isothermal Continuous Flow Stirred Tank Reactor (CFSTR) are analyzed. Together with its deficiency analysis, the CRN Theory provides a suitable framework to assert whether a particular reaction network has the capacity to support multiple steady states using the reaction mechanism structure alone. Through deficiency analysis, we argued that the presence of two surface catalytic sites during absorption-desorption of nitrogen (microscale) is causative of bistability (macroscale) in two of the three ammonia synthesis mechanisms here considered.
Métodos potenciales y electromagnéticos aplicados a la modelación bidimensional del volcán tipo maar “La Joyuela”, San Luis Potosí, México
Get PDF"Se presentan los resultados del estudio geofísico realizado en el volcán tipo maar
“La Joyuela” (LJ), que permitió caracterizar su morfología demostrando la
existencia de la diatrema asociada a la formación del cráter ubicado la profundidad
promedio de la anomalía a 153 m.
En el estudio se emplearon varias técnicas de prospección geofísica con métodos
potenciales (magnetometría y gravimetría) e inducidos (sondeos eléctricomagnéticos
de corriente directa y corriente alterna). Los datos que se obtuvieron
con estos métodos nos permitieron realizar interpretaciones con base a
propiedades físicas de las rocas como la susceptibilidad magnética, resistividad y
densidad.
En el trabajo de campo se cubrieron 45 Km lineales de magnetometría terrestre
en 15 líneas y 7 Km lineales en dos secciones gravimétricas. Además se
efectuaron dos sondeos eléctricos con abertura de electrodos de corriente (AB/2)
hasta 600 m y 7 sondeos audio-magnetotelúricos con fuente natural, con abertura
de dipolos de 50 m y 7 más con fuente controlada.
En el procesamiento de la información se utilizaron diferentes algoritmos
matemáticos como: filtro de Reducción al Polo, Continuaciones de Campo
Ascendentes, Derivadas, Señales Analíticas, entre otros. Que nos permitieron
resaltar las señales y obscurecer el ruido. En la inversión de los datos (modelado)
se utilizaron los algoritmos de Occam, Talwani y Gradientes Conjugados no
Lineales.
Los principales resultados de este estudio fueron: modelación de la geología del
subsuelo del maar LJ, la posible existencia de la diatrema y los remanentes del
dique basanítico por debajo del cráter.""In this work I present the results of a geophysical study of a maar type volcano
named La Joyuela, in San Luis Potosí, Mexico. I have characterized the
subsurface morphology and thus this has allowed me for the identification of a
possible diatreme structure underground, associated to the eruption at an average
depth of 153 m.
In order to cover the objectives of this study, various geophysical prospection
techniques have been used, in the like of potential methods (magnetic and gravity)
and induced methods (electro-magnetic surveys of direct and alternating current).
With the data produced using these geophysical methods I have been able to
make interpretations of the physical properties of the rocks in the area, such as
magnetic susceptibility, resistivity and density.
Field campaigns to collect magnetic data covered 45 linear kilometers in a total of
15 profiles. This was reinforced with two gravity surveys data covered 8 Km, two
vertical electrical soundings and 7 audio - magnetotelluric surveys.
In order to process the information we used different mathematical algorithms such
as the pole reduction filter, the ascending field continuations, derivatives, analytical
signals, amongst others. This allowed us to highlight the signal and reduce data
noise. For data inversion (modeling) we used the Occam and Talwani algorithms
and Nonlinear gradients conjugates.
The results obtained with this study helped me to model the subsurface geology
within La Joyuela maar volcano. The main new discovery is the possibility for the
existence of a diatreme structure and remnants of a basanite dyke below the
crater.
Surface modification of TiO2 with Ag nanoparticles and CuO nanoclusters for application in photocatalysis
Get PDF"Ag and CuO nanoparticles (NPs) synthesized on the surface of commercial TiO2 (P25) by radiolytic reduction were characterized by diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). In the case of modification with silver and copper, results from HAADF-STEM, EDS, XPS, and XAS show that Ag@CuO nanoparticles (large silver cores decorated with small clusters of CuO) were obtained on TiO2-P25. The photocatalytic properties of bare and modified TiO2-P25 were studied for phenol photodegradation and for acetic acid oxidation under UV and visible irradiation. The mechanisms involved in photo catalysis were studied by time-resolved microwave conductivity (TRMC) and action spectra (AS). The electronic properties of the surface-modified TiO2-P25 were studied by TRMC to follow the charge-carrier dynamics. The modification with Ag nanoparticles or CuO nanoclusters induces an increase in the photocatalytic activity under both IN and visible light. The photocatalytic activity of Ag@CuO/P25 is higher under-UV light but lower under visible light compared to the activity of CuO/P25 and Ag/P25. TRMC measurements show that surface modification of TiO2-P25 with Ag, CuO, and Ag@CuO nanoparticles plays a role in charge-carrier separation, increasing the activity under UV-light, and that Ag@CuO NPs are more efficient electron scavengers than Ag NPs and CuO nanoclusters. The localized surface plasmon resonance (LSPR) of Ag NPs and the narrow band gap of CuO induce an activity under visible light. The TRMC shows also responses under visible-light irradiation at different fixed wavelengths indicating that electrons are injected from Ag NPs in the conduction band (CB) of TiO2-P25. Moreover, under visible light, the photocatalytic activity of CuO/P25 is higher than that of plasmonic Ag/P25. CuO is able to activate TiO2-P25 in a wider range of wavelengths under visible-light irradiation, compared to the activation achieved by the presence of silver. The action spectra correlate with the-absorption spectra for irradiation wavelengths in the range of 350-470 nm proving that dem-xi-position of acetic acid is carried out by a photocatalytic mechanism.
Output-feedback proportional-integral-derivative-type control with multiple saturating structure for the global stabilization of robot manipulators with bounded inputs
Get PDF"An output-feedback proportional integral derivative-type control scheme for the global regulation of robot manipulators with constrained inputs is proposed. It guarantees the global stabilization objective-avoiding input saturation-releasing the feedback not only from the exact knowledge of the system structure and parameter values but also from velocity measurements. With respect to previous approaches of the kind, the proposed controller is expressed in a generalized form whence multiple saturating structures may be adopted, thus enlarging the degree of design flexibility. Furthermore, experimental tests on a two-degree-of-freedom direct-drive manipulator corroborate the efficiency of the proposed scheme.
Magnetocaloric Effect and Magnetocaloric Materials
No full textMagnetocaloric effect (MCE) is a heating or cooling of a magnetic material when the applied magnetic field changes. At the heart of the MCEs lays coupling between the magnetic moments and external magnetic field, and in some cases the MCE involves structural transitions concomitant with magnetic transitions. MCE can be used for cooling and may offer larger efficiencies than a conventional vapor-cycle refrigeration. The current goal is to find cheap and efficient magnetocaloric materials that can operate around room temperature. Structure and properties of known magnetocaloric materials are discussed and compared
Un modelo matemático y análisis dinámico de digestión anaerobia de la fracción orgánica soluble de residuos sólidos municipales orientado al diseño de control
No full text"A dynamical model for anaerobic digestion (AD) is proposed for the soluble organic fraction of solid waste. The model is proposed with the purpose of showing the feedback control of the process. The control scheme concerns the output regulation of the organic matter effluent by achieving desired operation conditions, which are featured by the operational stability. The operating conditions for the digester correspond to organic matter degradation and are named normal operation conditions, which are computed from nontrivial equilibrium. Both the acidogenic and the methanogenic stages are considered in dynamical model; including substrate and product inhibition. A PI feedback control is designed in order to illustrate the control problem is solvable.""Un modelo dinámico para digestión anaerobia es propuesto para la fracción orgánica soluble de residuos sólidos urbanos. El modelo es propuesto con el propósito de mostrar una ley de control del proceso. El esquema de control consiste en la regulación de la materia orgánica efluente como señal de salida mediante el mantenimiento de condiciones deseadas, las cuales incluyen la estabilidad operacional. Las condiciones de operación para el digestor corresponden a la degradación de la materia orgánica y son llamadas condiciones normales de operación, las cuales son calculadas de un equilibrio no trivial. El modelo dinámico considera las etapas acidogénica y metanogénica; substrato y la inhibición por producto. Un control PI retroalimentado es diseñado para ilustrar que el problema de control es resoluble.
Influence of sugarcane burning on soil carbon and nitrogen release under drought and evapotranspiration conditions in a Mexican sugarcane supply zone
Get PDF"Sugarcane cultivation is an agricultural activity of worldwide importance. This crop has been cultivated in Mexico for centuries, impacting important productive areas like the study region called Huasteca Potosina which is located at the Central-East part of Mexico. The relationship between soil conditions, weather and production per hectare allows identifying the edaphological and climatic conditions (aptitude levels) for cultivating sugarcane in the study area. The objective of this research work is to analyze the relation between the cultivated hectares and production of sugarcane. Likewise, to explain its behavior and interpret the contribution of N and C released to the atmosphere for burning sugar cane in association with events and meteorological parameters involved in the flux of water between soil and atmosphere such as drought, evapotranspiration and rainfall. The methods and indicators for burning waste provided by the Intergovernmental Panel on Climate Change (IPCC), the value of potential evapotranspiration as Thornthwaite and drought severity index were applied in order to understand the correlations between the drought severity index and potential evapotranspiration, and between C and N release and potential rainfall availability. The results show the increment of harvested hectares and the loss of water from the soil by the increase of periods of drought events and evapotranspiration. The volatilized nutrients in soil varied from 1.32 x 105 to 2.17 x 105 t for C and from 1.32 x 103 t to 2.17 x 103 t for N during the burning of sugarcane, affecting production levels with values fluctuating between 38 t/ha to 77 t/ha for the term of 1990-2010.""El cultivo de caña de azúcar es una actividad agrícola de importancia mundial llevada a cabo en México durante siglos, impactando importantes áreas productivas como la región de estudio llamada Huasteca Potosina, localizada al este central de México. La relación entre las condiciones del suelo, clima y producción por hectárea permite identificar las condiciones edafológicas y climáticas (niveles de aptitud) para cultivar la caña de azúcar en el área de estudio. Bajo este contexto, el objetivo fue analizar la relación entre las hectáreas cultivadas y la producción de caña de azúcar y explicar su comportamiento al interpretar las contribuciones del N y C liberados a la atmósfera por la quema de caña asociados a eventos y parámetros meteorológicos involucrados en el flujo de agua entre el suelo y la atmósfera como sequía, evapotranspiración y lluvia. Los métodos e indicadores para la quema de residuos provistos por el Panel Intergubernamental del Cambio Climático (IPCC. por sus siglas en inglés), el valor de la evapotranspiración potencial por Thornthwaite y el índice de severidad de la sequía fueron aplicados para comprender las correlaciones entre el índice de severidad de la sequía y la evapotranspiración potencial, así como entre el C y el N liberados y la disponibilidad potencial de lluvia. Los resultados muestran el incremento en las hectáreas cosechadas y la pérdida de agua del suelo por el aumento de los periodos de sequía y la evapotranspiración. Los nutrientes del suelo volatilizados, varían de 1.32 x 105 ton a 2.17 x 105 ton para C y 1.32 x 103 ton a 2.17 x 103 ton para N durante la quema de caña de azúcar, lo que afecta sus niveles de producción con valores que fluctúan entre 38 t/ha y 77 t/ha durante el periodo 1990-2010.