Adiabatic Electron-Phonon Interaction and High-Temperature Thermodynamics of A15 Compounds

Inelastic neutron scattering was used to measure the phonon densities of states of the A15 compounds V_3Si, V_3Ge, and V_3Co at temperatures from 10 to 1273 K. It was found that phonons in V_3Si and V_3Ge, which are superconducting at low temperatures, exhibit an anomalous stiffening with increasing temperature, whereas phonons in V_3Co have a normal softening behavior. First-principles calculations show that this anomalous increase in phonon frequencies at high temperatures originates with an adiabatic electron-phonon coupling mechanism. The anomaly is caused by the thermally induced broadening of sharp peaks in the electronic density of states of V_3Si and V_3Ge, which tends to decrease the electronic density at the Fermi level. These results show that the adiabatic electron-phonon coupling can influence the phonon thermodynamics at temperatures exceeding 1000 K

The use of free voluntary reading and reading comprehension strategies for the development of reading comprehension skills in english

Tesis (Profesor de Inglés para la Enseñanza Básica y Media y al grado académico de Licenciado en Educación)This study addresses the area of Reading Comprehension, a skill that needs attention in the Chilean Educational System. We explored the use of Reading Comprehension Strategies and Free Voluntary Reading with the purpose of examining the possible effects of Reading Comprehension Strategies and Free Voluntary Reading in a Mixed Methods Single Case Study about student’s reading skills and perceptions about reading by providing her with opportunities to freely select texts of her interest to be read in the school and also at home. The participant of this research study was trained on Reading Comprehension Strategies and was also given the opportunity to read texts of her own interest. As data collection instruments, pre-test, post-test and delayed post-tests were used, which gave us quantitative data, and to support this data we conducted an interview which gave us qualitative data about the perceptions of the participant. After the intervention we could see that the majority of students in the school were not motivated to read, and this fact was reflected in the low number of students who joined the study, since they had to do it voluntarily. The results obtained after analyzing the instruments helped us to confirm that the participant was able to develop and improve her reading skills with the help of the training on reading strategies and also by having the chance to freely read texts of her own interest.Este estudio aborda el área de comprensión de lectura, una habilidad que requiere atención en el sistema educativo chileno. Hemos explorado el uso de estrategias de comprensión lectora y de lectura voluntaria libre (Free Voluntary Reading) con el propósito de examinar los posibles efectos de estrategias de comprensión lectora y lectura voluntaria libre en las habilidades de lectura de los estudiantes y sus percepciones acerca de la lectura, proporcionándoles oportunidades de seleccionar libremente los textos de su interés para ser leídos en la escuela y también en el hogar. En un estudio de método mixto de caso único, la participante de esta investigación fue entrenada en estrategias de comprensión lectora y también se le dio la oportunidad de leer textos de su propio interés. Para la recolección de datos los instrumentos utilizados fueron pre-test, un post-test y post-test retrasado que nos dieron los datos cuantitativos, y para apoyar a estos datos se realizó una entrevista que nos dio datos cualitativos sobre las percepciones de los participantes. Después de la intervención pudimos ver que la mayoría de los estudiantes en el colegio no parecían motivados a leer, y este hecho se refleja en el bajo número de estudiantes que se unió al taller de lectura. Los resultados obtenidos después de la revisión de los instrumentos nos ayudaron a confirmar que la participante fue capaz de desarrollar sus habilidades de lectura con la ayuda del entrenamiento en estrategias de comprensión de lectura y a través de la lectura voluntaria

Validation of smart nanoparticles as controlled drug delivery systems: loading and pH-dependent release of pilocarpine

Micelles are good devices for use as controlled drug delivery systems because they exhibit the ability to protect the encapsulated substance from the routes of degradation until they reach the site of action. The present work assesses loading kinetics of a hydrophobic drug, pilocarpine, in polymeric micellar nanoparticles (NPs) and its pH-dependent release in hydrophilic environments. The trigger pH stimulus, pH 5.5, was the value encountered in damaged tissues in solid tumors. The new nanoparticles were prepared from an amphiphilic block copolymer, [(HEMA19%-DMA31%)-(FMA5%-DEA45%)]. For the present research, three systems were validated, two of them with cross-linked cores and the other without chemical stabilization. A comparison of their loading kinetics and release profiles is discussed, with the support of additional data obtained by scanning electron microscopy and dynamic light scattering. The drug was loaded into the NPs within the first minutes; the load was dependent on the degree of cross-linking. All of the systems experienced a boost in drug release at acidic pH, ranging from 50 to 80% within the first 48 h. NPs with the highest degree (20%) of core cross-linking delivered the highest percentage of drug at fixed times. The studied systems exhibited fine-tuned sustained release features, which may provide a continuous delivery of the drug at specific acidic locations, thereby diminishing side effects and increasing therapeutic rates. Hence, the studied NPs proved to behave as smart controlled drug delivery systems capable of responding to changes in pH.Peer ReviewedPostprint (published version

The bank of didactic resources as key axis in the processes of teaching - learning.

Los recursos didácticos son vías muy motivadoras que nos van a permitir desarrollar una adecuada intervención educativa. La utilización de diferentes medios didácticos previamente planificados ayudará a la práctica educativa y proporcionará al docente un mayor con trol en caso de posibles desajustes y una triunfante práctica educativa. Las adaptaciones curriculares han supuesto enormes avances para que el profesorado adapte al máximo los medios disponibles a las características concretas del alumnado que pre senta cualquier necesidad educativa. No obstante, para lograr progresos en el alumnado con cualquier alteración, se usa gran variedad de materiales de características muy diversas y variopintas que permitirán al docente un mayor margen de actuación ante cualquier ca suís tica que se le presente en el aula.Didactic resources are very motivational and allow us to develop a suitable educatio nal intervention. The use of different didactic media which have been previously planned will help educational practice and will give the teacher greater control in the event of po ssible imbalances and lead to successful educational practice. Cu rricular adjustments have meant enormous advances so that teachers can exploit available means to the maximum Nonetheless, to achieve progress with students with any al te ration, a wide variety of materials is used which will allow the teacher greater scope for ac tion when problems arise in the classroom.peerReviewe

Electron-phonon interactions and high-temperature thermodynamics of vanadium and its alloys

Inelastic neutron scattering was used to measure the phonon densities of states (DOSs) for pure V and solid solutions of V with 6 to 7at% of Co, Nb, and Pt, at temperatures from 10 K to 1323 K. Ancillary measurements of heat capacity and thermal expansion are reported on V and V-7at%Co and used to help identify the different sources of entropy. Pure V exhibits an anomalous anharmonic stiffening of phonons with increasing temperature. This anharmonicity is suppressed by Co and Pt, but not by isoelectronic Nb solutes. The changes in phonon frequency with alloying and with temperature both correlate to the decrease in electron density of states (DOS) at the Fermi level as calculated using density functional theory. The effects of both temperature and alloying can be understood in terms of an adiabatic electron-phonon interaction (EPI), which broadens sharp features in the electron DOS. These results show that the adiabatic EPI can influence the phonon thermodynamics at temperatures exceeding 1000 K, and that thermal trends of phonons may help assess the strength of the EPI

Observation of giant photocurrent gain in highly doped (In,Ga)N/GaN MQW-based photodiodes

The authors report on the observation of a giant photocurrent gain (>106) in highly doped (In,Ga)N/GaN multiple-quantum-well-based photodiodes, which decreases with temperature. This large photocurrent gain appears at low forward bias and strongly depends on the current transport mechanism. Results of capacitance-voltage measurements show that the photocurrent gain is related to the screening of the built-in electric field by charge accumulation. The role of the (Al,Ga)N electron blocking layer in current transport has been studied by comparing samples nominally identical except for the existence of this layer

The role of the brain in financial decisions : a viewpoint on neuroeconomics

In this article, we explain the important role neuroscience plays in economic and financial environments. Hence, we present neuroeconomics as a way to describe how decision-making processes affect brain activity, focusing especially on the importance of economic and financial decisions. We answer some questions regarding the role of emotions in finance, the psychological factors present in financial markets, and how neuropsychological stimuli affect our economic decisions. We conclude by citing the main research in the area of neuroscience in financial decision-making processes, and highlight further research projects in these areas

Propuesta de mejoramiento de la red de voz y datos de la Institución Educativa los Fundadores en el Municipio de Riosucio Caldas

En este proyecto se muestra el diseño de la red de sistemas de comunicaciones de la Institución Educativa Los Fundadores, el cual cumple respectivamente con las normas vigentes que rigen las redes de voz y datos como lo son la EIA/TIA En el diseño de la red de comunicaciones se muestra la distribución de los puntos de red, teléfono y televisión, que cumplen con las necesidades de la Institución Educativa Los Fundadores. Además de esto pueden ver con claridad la distribución de las salas de sistemas con sus respectivos racks. También se muestra una cotización del proyecto, el cual estará encargado de mejorar la red de Voz y Datos en base a sus ordenadores y de los sistemas de comunicaciones en la Institución

Organic Matter in Space - an Overview

Organic compounds are ubiquitous in space: they are found in diffuse clouds, in the envelopes of evolved stars, in dense star-forming regions, in protoplanetary disks, in comets, on the surfaces of minor planets, and in meteorites and interplanetary dust particles. This brief overview summarizes the observational evidence for the types of organics found in these regions, with emphasis on recent developments. The Stardust sample-return mission provides the first opportunity to study primitive cometary material with sophisticated equipment on Earth. Similarities and differences between the types of compounds in different regions are discussed in the context of the processes that can modify them. The importance of laboratory astrophysics is emphasized.Comment: Introductory overview lecture presented at IAU Symposium 251, "Organic matter in space", held at Hong Kong, February 2008; to appear in IAU Symposium 251 proceedings, Cambridge University Press, ed. S. Kwok et a