THE LINK BETWEEN FARMGATE AND WORLD PRICES IN THE WAKE OF TRADE LIBERALIZATION: THE CASE OF COLOMBIA

The study measures the extent to which farmgate price levels have effectively increased their degree of integration with world price movements following trade liberalization in Columbia. Results show that the extent of integration varies greatly depending upon the crop, and that market-specific policies have isolated some farmers from international influences.Demand and Price Analysis, International Relations/Trade, Marketing,

Modest : water heater smart control and management

Recent advances in microcontroller technology have given rise to the Internet of Things (IoT), which has created new opportunities in energy automation and optimization. Smart devices and appliances are able to collect operational data, and combine it with data analytics to facilitate optimized control of household electronics. For example, data collected from a smart thermostat can be combined with third-party data sources such as; 15­min interval electricity usage data collected from a smart meter, weather data from numerous sources, utility billing rate data, and data from other smart appliances in the home to optimize the energy usage of residential heating and cooling system. The goals for this project are: 1) Design a control system that enables collection of temperature, flow rate and power data, 2) implement the control system in an electric water heater for residential use, 3) create a connection between a cloud server and the water heater control system for data collection, and 4) develop an advanced control algorithm for water heater thermal management. The main contribution is meant to be a cloud-based infrastructure for IoT aggregation and control, a kind of artificial intelligence for IoT and energy automation.Electrical and Computer Engineerin

Nonadiabatic Study of Dynamic Electronic Effects during Brittle Fracture of Silicon

It has long been observed that brittle fracture of materials can lead to emission of high energy electrons and UV photons, but an atomistic description of the origin of such processes has lacked. We report here on simulations using a first-principles-based electron force field methodology with effective core potentials to describe the nonadiabatic quantum dynamics during brittle fracture in silicon crystal. Our simulations replicate the correct response of the crack tip velocity to the threshold critical energy release rate, a feat that is inaccessible to quantum mechanics methods or conventional force-field-based molecular dynamics. We also describe the crack induced voltages, current bursts, and charge carrier production observed experimentally during fracture but not previously captured in simulations. We find that strain-induced surface rearrangements and local heating cause ionization of electrons at the fracture surfaces

Microclimatic behavior of a screen house proposed for horticultural production in low-altitude tropical climate conditions

In developing countries, horticultural production in low-altitude tropical climate conditions is often limited by biotic and abiotic factors. In these countries, the implementation of highly technical greenhouses is not feasible due to economic, social and cultural issues related to farmers. Therefore, one of the alternatives that has taken a great boom is the use of screen house structures (SH), although information on the microclimatic behavior of these is still limited. The objective of this research was to use an experimentally validated 3D CFD numerical simulation model to study the thermal behavior and airflow patterns in an SH located in the Colombian Caribbean region during the daytime hours (6:00 to18:00 h). The results obtained showed that the air flow patterns inside the SH showed speed reductions of up to 68% with respect to the speed of the external wind. It was also found that the thermal behavior inside the SH was quite homogeneous, the average temperature values in the structures ranged between 23.9 and 39 °C and the difference with external environment temperature did not exceed 1.8 °C. It was concluded that the implementation of this type of structure could be an useful technological tool for the optimization of horticultural production in low-altitude tropical climate regions.In developing countries, horticultural production in low-altitude tropical climate conditions is often limited by biotic and abiotic factors. In these countries, the implementation of highly technical greenhouses is not feasible due to economic, social and cultural issues related to farmers. Therefore, one of the alternatives that has taken a great boom is the use of screen house structures (SH), although information on the microclimatic behavior of these is still limited. The objective of this research was to use an experimentally validated 3D CFD numerical simulation model to study the thermal behavior and airflow patterns in an SH located in the Colombian Caribbean region during the daytime hours (6:00 to18:00 h). The results obtained showed that the air flow patterns inside the SH showed speed reductions of up to 68% with respect to the speed of the external wind. It was also found that the thermal behavior inside the SH was quite homogeneous, the average temperature values in the structures ranged between 23.9 and 39 °C and the difference with external environment temperature did not exceed 1.8 °C. It was concluded that the implementation of this type of structure could be an useful technological tool for the optimization of horticultural production in low-altitude tropical climate regions

Effect of surface oxidation on the electronic transport properties of phosphorene gas sensors: a computational study

The potential for phosphorene-based devices has been compromised by the material's fast degradation under ambient conditions. Its tendency to fully oxidize under O₂-rich and humid environments, leads to the loss of its appealing semiconducting properties. However, partially-oxidized phosphorene (po-phosphorene), has been demonstrated to remain stable over significantly longer periods of time, thereby enabling its use in sensing applications. Here, we present a computational study of po-phosphorene-based gas sensors, using the Density-Functional-based Tight Binding (DFTB) method. We show that DFTB accurately predicts the bandgap for the pristine material and po-phosphorene, the electronic transport properties of po-phosphorene at different surface oxygen concentrations, and the appropriate trends in Density-of-States (DOS) contributions caused by adsorbed gas molecules, to demonstrate its potential application in the development of gas sensors. Results are compared against the more traditional and expensive Density Functional Theory (DFT) method using generalized gradient approximation (GGA) exchange–correlation functionals, which significantly underestimates the material's bandgap

Política tributaria, informalidad, y rigideces en los salarios reales.

Los países en desarrollo presentan un sector informal relevante asociado con bajos niveles de productividad. Los efectos de las políticas tributarias sobre los niveles de informalidad dependen de las rigideces del mercado laboral. En el presente artículo se propone un modelo de búsqueda y emparejamiento en un mercado laboral segmentado para entender la interacción entre las políticas tributarias y la aplicación de la ley sobre el sector formal. Los resultados analíticos muestran que, disminuir los impuestos a la nómina genera aumentos en la demanda de empleo formal, mientras que un aumento en el gasto de auditar a las empresas disminuye la oferta de empleo informal. El modelo sugiere un impacto significativo en la reducción de la informalidad al combinar las políticas tributarias. Además, la magnitud del efecto de las políticas depende de las rigideces en los salarios reales. De esta forma, cuando la economía presenta altas rigideces en los salarios reales, las políticas tributarias tienen un mayor efecto sobre la reducción de la informalidad.Developing countries have a vast informal sector generally associated with low productivity levels. The response of informal employment to tax policies might depend on labor market rigidities. This paper proposes a theoretical framework consisting of a search and matching model with segmentation in the labor market to understand how tax policies and enforcement interact to determine the size of the formal sector. The analytical results show that decreasing payroll taxes increases formal employment demand, and enforcement expenditure decreases informal employment offers. The model suggests that a tax policy combination leads to a significant impact on informality reduction. Moreover, the magnitude of the effect of tax policies depends on real wage rigidities, i.e., when the economy faces high real wage rigidities, the tax policies have a higher effect on informality reduction.Política tributaria, informalidad, y rigideces en los salarios reales Enfoque La mayoría de los países en desarrollo presentan altas tasas de informalidad junto con rigideces en el mercado laboral. Para el caso de Colombia, se observa que la informalidad laboral es persistente a lo largo del tiempo. En nuestro artículo, investigamos el efecto de las políticas tributarias sobre el comportamiento de la informalidad, el desempleo y el gasto público, utilizando un modelo de equilibrio general que considera las dinámicas en el proceso de contratación y la rigidez del mercado laboral. Contribución La persistencia y relevancia del sector informal en las economías en desarrollo, se debe en parte, a la rigidez del mercado laboral y a los efectos de las políticas tributarias sobre las decisiones de las empresas y de los trabajadores. Para entender este comportamiento, nuestra investigación tiene en cuenta las decisiones de los trabajadores en un contexto en el que persisten las rigideces en los salarios reales a lo largo del tiempo, junto con las dinámicas de búsqueda y emparejamiento que se dan en el proceso de contratación dentro del sector formal. De esta forma, observamos los efectos de las políticas tributarias, definidas como las variaciones en los impuestos a la nómina y en el gasto de auditar a las empresas, sobre las decisiones optimas de los trabajadores y de las firmas, logrando incorporar los cambios de las políticas sobre las decisiones individuales de los agentes y entender el efecto a nivel agregado en la economía. Resultados Encontramos que la combinación de políticas tributarias como reducir los impuestos a la nómina e incrementar el gasto de auditar a las empresas, contribuye significativamente a reducir la informalidad laboral, aumentando la formalidad, mientras se disminuye el desempleo. Además, mostramos que es posible aplicar las políticas mencionadas previamente, mientras se cumple con un objetivo en el balance fiscal por parte del gobierno. De igual forma, los resultados sugieren que las rigideces en los salarios reales son relevantes para entender la magnitud del efecto de las políticas tributarias sobre la reducción de la informalidad. En este sentido, si la economía presenta mayores rigideces en los salarios reales, las políticas tributarias tienen un mayor efecto en la reducción del empleo informal. Finalmente, los resultados también señalan la posibilidad de reducir el sector informal al hacer el mercado laboral más flexible. Frase destacada: “La combinación de políticas tributarias como reducir los impuestos a la nómina e incrementar el gasto de auditar a las empresas, contribuye significativamente a reducir la informalidad laboral, aumentando la formalidad, mientras se disminuye el desempleo”

Estudio exploratorio : el rol de las tecnologías cognitivas en los centros de excelencia en el contexto de la Cuarta Revolución Industrial

Al interior de las organizaciones se tienen diferentes áreas que se encargan de la creación de nuevos productos y servicios, de intercambiar las mejores prácticas existentes tanto en el interior como en el exterior de la organización y de incorporar nuevas tecnologías emergentes, con la finalidad de poder mantenerse vigentes y generar los resultados esperados en procura de garantizar la sostenibilidad. Pero en la actualidad existe un área que es capaz de reunir todas esas funciones en un solo lugar, esa área se conoce como los Centros de Excelencia. Estos centros serán el objeto de análisis de esta investigación bajo la modalidad de estudio exploratorio, debido a que hasta la fecha, en nuestro medio, se han realizado muy pocas investigaciones en las cuales se describan las principales definiciones, los diferentes tipos y las características esenciales con las que deben contar estos centros en el contexto actual de la Cuarta Revolución Industrial, donde se han potenciado una serie de tecnologías cognitivas que tienen la capacidad de hacer tareas que solo los humanos éramos capaces de hacer por tener incorporado un conocimiento previo. Este análisis se hizo en tres etapas: en las primeras dos se plasmaron de forma individual las principales definiciones, características y matices de los conceptos de Centros de Excelencia, Cuarta Revolución Industrial y las tecnologías cognitivas, finalizando con una tercera etapa donde se concluye con un análisis de las tecnologías cognitivas que deben incorporar estos centros, para poderse catalogar como Centros de Excelencia Cognitivos.Within the organizations, there are many different areas that are in charge of the development of new products and services. These areas are also constantly exchanging existing practices and knowledge not only within the organization but also outside of it. They are responsible of incorporating and integrating new technologies with the final purpose of keeping themselves up to date with the company and its goals while constantly generating results that guarantee sustainability. Nowadays exists an area capable of gathering all these functions in one place, the Centers of Excellence. These Centers will be the target of analysis within this research under the modality of exploratory study. This is due to the fact that up to this date, in our industry, very few investigations exist that describe the main functions, different types and essential capabilities that these centers need to have in the context of the Fourth Industrial Revolution in which a series of cognitive technologies have been enhanced. These technologies have the capacity of performing tasks that only humans used to be able to do so due to previously acquired knowledge. This analysis was performed in three stages: In the first two, the main definitions, characteristics and tones for the main concepts of the Centers of Excellence, Fourth Industrial Revolution and cognitive technologies are explained individually. The last stage concludes with a depth analysis of the cognitive technologies that need to be incorporated in The Centers to achieve the categorization of Cognitive Centers of Excellence

Polar Network Index as a magnetic proxy for the solar cycle studies

The Sun has a polar magnetic field which oscillates with the 11 year sunspot cycle. This polar magnetic field is an important component of the dynamo process which is operating in the solar convection zone and produces the sunspot cycle. We have systematic direct measurements of the Sun's polar magnetic field only from about mid 1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca K spectroheliograms taken in Kodaikanal Solar Observatory during 1904 - 2007 have now been digitized with the 4k x 4k CCD and have higher resolution (0.86 arcsec) than the other available historical datasets. From these Ca-K spectroheliograms, we have developed a completely new proxy (Polar Network Index, PNI) for the Sun's polar magnetic field. We calculate the PNI from the digitized images using an automated algorithm and calibrate our measured PNI against the polar field as measured by the Wilcox Solar Observatory for the period of 1976 - 1990. This calibration allows us to estimate polar fields for the earlier period up to 1904. The dynamo calculations done with this proxy as input data reproduce the Sun's magnetic behavior for the past century reasonably well.Comment: 19 pages, 5 figures Accepted for publication in APJ

Elucidation of the dynamics for hot-spot initiation at nonuniform interfaces of highly shocked materials

The fundamental processes in shock-induced instabilities of materials remain obscure, particularly for detonation of energetic materials. We simulated these processes at the atomic scale on a realistic model of a polymer-bonded explosive (3,695,375 atoms/cell) and observed that a hot spot forms at the nonuniform interface, arising from shear relaxation that results in shear along the interface that leads to a large temperature increase that persists long after the shock front has passed the interface. For energetic materials this temperature increase is coupled to chemical reactions that lead to detonation. We show that decreasing the density of the binder eliminates the hot spot