Exploring the Photophysical Properties of Molecular Systems Using Excited State Accelerated ab Initio Molecular Dynamics.

In the present work, we employ excited state accelerated ab initio molecular dynamics (A-AIMD) to efficiently study the excited state energy landscape and photophysical topology of a variety of molecular systems. In particular, we focus on two important challenges for the modeling of excited electronic states: (i) the identification and characterization of conical intersections and crossing seams, in order to predict different and often competing radiationless decay mechanisms, and (ii) the description of the solvent effect on the absorption and emission spectra of chemical species in solution. In particular, using as examples the Schiff bases formaldimine and salicylidenaniline, we show that A-AIMD can be readily employed to explore the conformational space around crossing seams in molecular systems with very different photochemistry. Using acetone in water as an example, we demonstrate that the enhanced configurational space sampling may be used to accurately and efficiently describe both the prominent features and line-shapes of absorption and emission spectra

ALGORITHM TO EXTRACT MODEL PARAMETERS OF PARTIALLY SHADED PHOTOVOLTAIC MODULES

Uneven irradiation, due to partial shading, can produce hot spots in photovoltaic modules. A classical solution to avoid hot spot consists in using bypass diodes in antiparallel to series-connected cell groups. This solution brings a new problem: the presence of multiple local maximum power points. We present a simple algorithm for fast extraction of the model parameters of partially shaded photovoltaic panels with bypass diodes. An example of the application of the proposed algorithm is illustrated using the data from a real monocrystalline silicon technology photovoltaic module measured under uniform illumination and partial shading conditions. The possibility of using the algorithm as a practical approximate solution is also discussed. The simulations, using only four parameters, represent reasonably well the measured data

On the Role of Dewetting Transitions in Host-Guest Binding Free Energy Calculations.

We use thermodynamic integration (TI) and explicit solvent molecular dynamics (MD) simulation to estimate the absolute free energy of host-guest binding. In the unbound state, water molecules visit all of the internally accessible volume of the host, which is fully hydrated on all sides. Upon binding of an apolar guest, the toroidal host cavity is fully dehydrated; thus, during the intermediate λ stages along the integration, the hydration of the host fluctuates between hydrated and dehydrated states. Estimating free energies by TI can be especially challenging when there is a considerable difference in hydration between the two states of interest. We investigate these aspects using the popular TIP3P and TIP4P water models. TI free energy estimates through MD largely depend on water-related interactions, and water dynamics significantly affect the convergence of binding free energy calculations. Our results indicate that wetting/dewetting transitions play a major role in slowing the convergence of free energy estimation. We employ two alternative approaches-one analytical and the other empirically based on actual MD sampling-to correct for the standard state free energy. This correction is sizable (up to 4 kcal/mol), and the two approaches provide corrections that differ by about 1 kcal/mol. For the system considered here, the TIP4P water model combined with an analytical correction for the standard state free energy provides higher overall accuracy. This observation might be transferable to other systems in which water-related contributions dominate the binding process

The direct boundary element method: 2D site effects assessment on laterally varying layered media (methodology)

The Direct Boundary Element Method (DBEM) is presented to solve the elastodynamic field equations in 2D, and a complete comprehensive implementation is given. The DBEM is a useful approach to obtain reliable numerical estimates of site effects on seismic ground motion due to irregular geological configurations, both of layering and topography. The method is based on the discretization of the classical Somigliana's elastodynamic representation equation which stems from the reciprocity theorem. This equation is given in terms of the Green's function which is the full-space harmonic steady-state fundamental solution. The formulation permits the treatment of viscoelastic media, therefore site models with intrinsic attenuation can be examined. By means of this approach, the calculation of 2D scattering of seismic waves, due to the incidence of P and SV waves on irregular topographical profiles is performed. Sites such as, canyons, mountains and valleys in irregular multilayered media are computed to test the technique. The obtained transfer functions show excellent agreement with already published results

Dripping Faucet Dynamics Clarified by an Improved Mass-Spring Model

An improved mass-spring model for a dripping faucet is presented. The model is constructed based on the numerical results which we recently obtained from fluid dynamical calculations. Both the fluid dynamical calculations and the present mass-spring model exhibit a variety of complex behavior including transition to chaos in good agreement with experiments. Further, the mass-spring model reveals fundamental dynamics inherent in the dripping faucet system.Comment: 17 pages, 17 figure

El proceso de formulación de un Plan de Desarrollo Institucional (PDI): reflexiones a partir de la experiencia de la expedición académica en el Liceo Celedón

This article is part of the final results and the discursive developments achieved in the framework of the project Expedition Celedon in 2011 in its academic component of formulation of the ten-year Development Plan. (PDI). This project is based on research processes that have generated relevant scientific knowledge in academia and relevant social; from the systematization of the process and the results of the exercise of community involvement that led to the structuring of the PDI. Underlying the nature of lecturers and researchers on the basis of the conception of the nature of the educational institution; assumed a perspective emerging as social fabric, as communications network and senses, such as merger of formal and social components such as complex systemic unity, as avocado uncertainty... as an organization built scenario and that is socially constructed.Este artículo hace parte de los resultados finales y las elaboraciones discursivas logradas en el marco del Proyecto Expedición Celedón en el año 2011, en su componente académico de Formulación del Plan Decenal de Desarrollo (PDI). El Proyecto está sustentado en procesos de investigación que han generado  conocimiento científico, relevante en lo académico y pertinente en lo social, a partir de la sistematización del proceso y los resultados del ejercicio de participación comunitaria que condujeron a la estructuración del PDI. Se sustenta la naturaleza del PDI sobre la base de la concepción de la naturaleza misma de la institución educativa, asumida desde una perspectiva emergente como tejido social, como red de comunicaciones y sentidos, como fusión de componentes formales y sociales, como unidad sistémica compleja, como escenario avocado a la incertidumbre… como organización construida y que se construye socialmente. Se plantea el PDI como expresión de un ejercicio comprensivo y reflexivo sobre la realidad, formal y social de la institución educativa. En esta experiencia se sustenta que más allá del propio PDI, lo importante es la interpelación de la  cultura institucional para fortalecer la organización educativa bajo los rasgos de una institución autogenética, que al tiempo que se preserva y se revoluciona, mantiene su identidad. Se trata de un proceso de planeación que reconcilia el manejo de los discursos pedagógicos y administrativos en función del desarrollo de una organizacional que ante todo es educativa y en consecuencia pedagógica, dado el carácter reflexivo y transformativo que define el proceso de planeación

Development plan; educational institution; social construction of reality; resignification.

This article is part of the final results and the discursive developments achieved in the framework of the project Expedition Celedon in 2011 in its academic component of formulation of the ten-year Development Plan. (PDI). This project is based on research processes that have generated relevant scientific knowledge in academia and relevant social; from the systematization of the process and the results of the exercise of community involvement that led to the structuring of the PDI. Underlying the nature of lecturers and researchers on the basis of the conception of the nature of the educational institution; assumed a perspective emerging as social fabric, as communications network and senses, such as merger of formal and social components such as complex systemic unity, as avocado uncertainty... as an organization built scenario and that is socially constructed. </p

El proceso de formulación de un Plan de Desarrollo Institucional (PDI): reflexiones a partir de la experiencia de la expedición académica en el Liceo Celedón

This article is part of the final results and the discursive developments achieved in the framework of the project&nbsp;Expedition Celedon in 2011 in its academic component of formulation of the ten-year Development Plan. (PDI).&nbsp;This project is based on research processes that have generated relevant scientific knowledge in academia&nbsp;and relevant social; from the systematization of the process and the results of the exercise of community&nbsp;involvement that led to the structuring of the PDI. Underlying the nature of lecturers and researchers on the basis&nbsp;of the conception of the nature of the educational institution; assumed a perspective emerging as social fabric,&nbsp;as communications network and senses, such as merger of formal and social components such as complex&nbsp;systemic unity, as avocado uncertainty... as an organization built scenario and that is socially constructed.Este artículo hace parte de los resultados finales y las elaboraciones discursivas logradas en el marco&nbsp;del Proyecto Expedición Celedón en el año 2011, en su componente académico de Formulación del Plan&nbsp;Decenal de Desarrollo (PDI). El Proyecto está sustentado en procesos de investigación que han generado &nbsp;conocimiento científico, relevante en lo académico y pertinente en lo social, a partir de la sistematización del&nbsp;proceso y los resultados del ejercicio de participación comunitaria que condujeron a la estructuración del&nbsp;PDI. Se sustenta la naturaleza del PDI sobre la base de la concepción de la naturaleza misma de la institución&nbsp;educativa, asumida desde una perspectiva emergente como tejido social, como red de comunicaciones y&nbsp;sentidos, como fusión de componentes formales y sociales, como unidad sistémica compleja, como escenario&nbsp;avocado a la incertidumbre… como organización construida y que se construye socialmente. Se plantea el&nbsp;PDI como expresión de un ejercicio comprensivo y reflexivo sobre la realidad, formal y social de la institución&nbsp;educativa. En esta experiencia se sustenta que más allá del propio PDI, lo importante es la interpelación de la &nbsp;cultura institucional para fortalecer la organización educativa bajo los rasgos de una institución autogenética, que al tiempo que se preserva y se revoluciona, mantiene su identidad. Se trata de un proceso de planeación que reconcilia el manejo de los discursos pedagógicos y administrativos en función del desarrollo de una organizacional que ante todo es educativa y en consecuencia pedagógica, dado el carácter reflexivo y transformativo que define el proceso de planeación