2,496 research outputs found
Control over stress induces plasticity of individual prefrontal cortical neurons: A conductance-based neural simulation
Behavioral control over stressful stimuli induces resilience to future conditions when control is lacking. The medial prefrontal cortex(mPFC) is a critically important brain region required for plasticity of stress resilience. We found that control over stress induces plasticity of the intrinsic voltage-gated conductances of pyramidal neurons in the PFC. To gain insight into the underlying biophysical mechanisms of this plasticity we used the conductance- based neural simulation software tool, NEURON, to model the increase in membrane excitability associated with resilience to stress. A ball and stick multicompartment conductance-based model was used to realistically fit passive and active data traces from prototypical pyramidal neurons in neurons in rats with control over tail shock stress and those lacking control. The results indicate that the plasticity of membrane excitability associated with control over stress can be attributed to an increase in Na+ and Ca2+ T-type conductances and an increase in the leak conductance. Using simulated dendritic synaptic inputs we observed an increase in excitatory postsynaptic summation and amplification resulting in elevated action potential output. This realistic simulation suggests that control over stress enhances the output of the PFC and offers specific testable hypotheses to guide future electrophysiological mechanistic studies in animal models of resilience and vulnerability to stress
Mejoramiento de la refractariedad de arcillas por lavado o intercambio iónico
Se estudió el mejoramiento de la refractariedad da arcillas que, a pesar de tener un elevado contenido de alúmina, presentaban un bajo cono pirométrico equivalente. El tratamiento se realizó por lavado con agua y por intercambio iónico.
Como se esperaba, después de los tratamientos mencionados, se logró mejorar el C.P.E. de las arcillas tratadas, tanto por lavado como por intercambio iónico con soluciones acuosas de ácido clorhídrico y acetato de amonio.
Se indican en el texto las condiciones experimentales y se proporcionan los resultados obtenidos.The improvement of the refractoriness of clays having a high content of aluminium oxide and a very low P.C.E. was studied after treating them by water and by ionic exchange.
As it was expected the P.C.E. of the clays under treatment was improved not only by ionic exchange with aqueous solutions of hydrochloric acid and ammonium acetate, but also washing them with water* The experimental conditions and the results obtained were presented in this paper
Using Taxes to Manage a Multigear Fishery: An Application to a Spanish Fishery
When fishing gears alter the composition of fish populations or modify the recruitment rate, it is advisable to include the degree of their fishing selectivity in the analysis. Fishing selectivity can cause two different management problems: interspecies selectivity or by‐catch of fish stocks for which no quota has been set by the regulator. The case study is the Spanish fishery of hake (Merlucius merlucius), where the fleet operates using two main gears; most of the vessels are trawlers but a few boats use longlines and other fixed gears. Fishery management by means of effort taxes and how the degree of intraspecies selectivity may affect the resource and tax levels are analyzed. The results show that the tax level will depend on the social value of the marine stock, the marginal productivity of each fleet\u27s effort, and the effect that the fishing activity of each one has on the growth of the hake biomass
Management of a fishery using taxes: The European hake fishery
The management by means of taxes of a fishery in which the fishing technology of the fleets has different effects on resource is analysed in this paper. This effect can be included in the natural growth of the marine resource function itself. The results show that the tax equilibrium level depends on shadow price, marginal productivity of the effort and effect of each gear on natural growth. The fleet that has a greater impact on resource will pay a higher rate of tax. And this rate will fall as the fleet in question improves its degree of fishing selectivity. Likewise we present some economic policy recommendations for this fishery.taxes, intra-species selectivity, European hake.
Strain behavior of lanthanum modified BiFeO3 thin films prepoared via soft chemical method
Pure and lanthanum modified BFO LaxBi1−xFeO3, x=0.0, 0.08, 0.15, 0.30 thin films were
fabricated on Pt 111 /Ti/SiO2 / Si substrates by the soft chemical method. The effect of La
substitution on the structural and electrical properties was studied. Scanning electron microscopy,
x-ray diffraction, and Raman spectroscopy have been employed to characterize the thin films while
the piezoelectric measurements were carried out using a setup based on an atomic force microscope.
It was found that La-doped BFO thin films exhibited good ferroelectric properties, such as improved
leakage current density and retention-free characteristics. The unipolar strain is strongly reduced by
the amount of lanthanum added to the syste
Neuroglial involvement in abnormal glutamate transport in the cochlear nuclei of the Igf1—/— mouse
Insulin-like growth factor 1 (IGF-1) is a powerful regulator of synaptic activity and a
deficit in this protein has a profound impact on neurotransmission, mostly on excitatory
synapses in both the developing and mature auditory system. Adult Igf1—/— mice
are animal models for the study of human syndromic deafness; they show altered
cochlear projection patterns into abnormally developed auditory neurons along with
impaired glutamate uptake in the cochlear nuclei, phenomena that probably reflect
disruptions in neuronal circuits. To determine the cellular mechanisms that might
be involved in regulating excitatory synaptic plasticity in 4-month-old Igf1—/— mice,
modifications to neuroglia, astroglial glutamate transporters (GLTs) and metabotropic
glutamate receptors (mGluRs) were assessed in the cochlear nuclei. The Igf1—/— mice
show significant decreases in IBA1 (an ionized calcium-binding adapter) and glial
fibrillary acidic protein (GFAP) mRNA expression and protein accumulation, as well
as dampened mGluR expression in conjunction with enhanced glutamate transporter
1 (GLT1) expression. By contrast, no differences were observed in the expression
of glutamate aspartate transporter (GLAST) between these Igf1—/— mice and their
heterozygous or wildtype littermates. These observations suggest that congenital IGF-1
deficiency may lead to alterations in microglia and astrocytes, an upregulation of GLT1,
and the downregulation of groups I, II and III mGluRs. Understanding the molecular,
biochemical and morphological mechanisms underlying neuronal plasticity in a mouse
model of hearing deficits will give us insight into new therapeutic strategies that could
help to maintain or even improve residual hearing when human deafness is related to
IGF-1 deficiencyThis work was supported by the Spanish Ministerio de Economía
y Competitividad (MINECO; SAF2016-788898-C2-1R) to JJ and
VF-S; Seventh Framework Programme (FP7)-HEALTH-
2012-INNOVATON (#304925) to JJ; CIBERER/FEDER
ACCI-ER16P5AC7091 and ER17P5AC7612 to LR-R;
and Spanish MINECO/FEDER (SAF2014-53979-R), FP7-
PEOPLE-2013-IAPP TARGEAR, CIBERER/FEDER (ACCIER16P5AC7091
and ER17P5AC7612) to IV-N. LR-R holds a
contract supported by CIBERER (Institute of Health Carlos III)
co-financed with FEDER fund
Polymer waste materials as fillers in polymer mortars: experimental and finite elements simulation
Serious environmental problems are due to large amounts of polymer waste, which are mostly thrown into landfills. As we known, polymer composites has been used to produce a variety of products like acid tanks, manholes, drains, highway median barriers, and so forth. One option is to use waste polymers as aggregates in polymer composites. In this work, waste polymers (PET, polycarbonate and automotive tires), partially replaced silica sand in polyester based mortar. Waste particles (0.7–2.36 mm), in concentrations of 1, 2 and 3% by weight, were used. The polymer mortar specimens were subjected to compressive and flexural tests, and the elasticity modulus was calculated. In addition, mechanical values were calculated by Finite Element Method (FEM), and compared with experimental data. Surface morphology and degree of crystallinity of waste particles were analyzed by SEM and XRD techniques, respectively. The results show improvement on the mechanical strength (up to 20%) for polymer mortar with waste PET; but lower mechanical values when adding polycarbonate or tire particles, compared to control mortar. These mechanical results can be related to the crystallinity degree, because PET particles shown higher crystallinity than those for polycarbonate and tire particles. This work is an alternative to reduce environmental contamination through to use waste polymers as fillers in polymer mortars. Keywords: Polymer waste, Polymer mortar, Polyethylene terephthalate, Polycarbonate, Tire rubber, Mechanical propertie
Reflections on an educational program on moral and civic virtues and values in secondary schools. A case study in Mexico.
The research we present is part of the project Researching and Promoting Character Education in Latin American Secondary Schools funded by the Templeton World Charity Foundation.In this research work we present a case study, focusing on the values program implemented in a Mexican public school in the central area of the country. Our exploration of the capacity of the school when implementing the values program is based on the analysis of documents provided by the school which are related with the project, semi-structured interviews, in-depth interviews, images and the participatory observation carried out in the school over a period of three weeks. The wealth of informants (principals, teachers, pupils and parents) allowed us to gather a broader variety of information on the reality of the values program applied
Study of the cheese salting process by dielectric properties at microwave frequencies
[EN] The salting process involves complex phenomena that affect the overall quality of cheese due to its effect on water activity and induced biochemical changes. The permittivity of cheese was analysed throughout the cheese salting treatment in order to relate it to water and salt transport. The salting treatment was carried out using 25% (wily) sodium chloride brine at 4 degrees C. The samples were immersed in a vessel containing the osmotic solution with continuous stirring, for 0, 10, 20, 30, 40, 50, 60, 90, 120, 180, 240, 360, 480, 720, 900 and 1440 min. Samples were subsequently equilibrated in an isothermal chamber at 4 degrees C for 24 h. Mass, volume, surface water activity, moisture, ion content and permittivity were determined in fresh and salted samples. Permittivity was measured from 500 MHz to 20 GHz, using an openended coaxial probe connected to a Vector Network Analyser. The results showed that measurements at 20 GHz explain the water loss and water flux in the overall product. The state of the electrolytes in cheese can be followed using the ionic conductivity at 500 MHz. A coupled measurement of permittivity at 20 GHz and 500 MHz can predict the chemical species involved in the cheese salting process, and its structural changes. In conclusion, the measurement of permittivity in the microwave range can be used to monitor the salting cheese process. (C) 2018 Elsevier Ltd. All rights reserved.The authors acknowledge financial support from the Spanish Ministerio de Economia, Industria y Competitividad, Programa Estatal de I+D+i orientada a los Retos de la Sociedad AGL2016-80643-R. Author J. Velazquez-Varela thanks the Consejo Nacional de Ciencia y Tecnologia (CONACyT) of Mexico for its support. This paper was published under the frame of the European Social Fund, Human Resources Development Operational Programme 2007-2013, project no. POSDRU/159/1.5/S/132765.Velazquez-Varela, J.; Castro Giraldez, M.; Cuibus, L.; Tomás-Egea, JÁ.; Socaciu, C.; Fito Suñer, PJ. (2018). Study of the cheese salting process by dielectric properties at microwave frequencies. Journal of Food Engineering. 224:121-128. https://doi.org/10.1016/j.jfoodeng.2017.12.024S12112822
An exploratory Delphy study on Character Education in Latin-American countries: Argentina, Colombia and Mexico
En el proyecto Researching and Promoting Character Education in Latin American Secondary Schools, financiado por la Templeton World Charity Foundation, nos aproximamos a la percepción que de la Educación del Carácter se tiene en Argentina, Colombia y México. La Educación del Carácter integra las propuestas para promover la ciudadanía.
Para el inicio de esta investigación elaboramos un estudio piloto basándonos en la metodología Dephi, con el objetivo de discernir cuáles son los temas más candentes alrededor de la Educación del Carácter en estos países. Esta metodología -rigurosa y de fácil manejo- permite la obtención de un conocimiento en profundidad sobre la problemática de la Educación del Carácter.
Contamos con la participación de diferentes expertos del ámbito académico, escolar y administrativo. Durante el proceso realizamos tres interacciones con los expertos para alcanzar un mayor consenso en sus opiniones. Para ello aplicamos dos rondas de preguntas cerradas y abiertas con las que obtener una mayor riqueza y convergencia en los datos obtenidos.
Como resultado constatamos que la Educación del Carácter no es un término habitual en el ámbito educativo de estos países. Además, en este tipo de educación incide la influencia y relación entre los agentes y el currículum explícito-oculto en la escuela
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