Economies of Scale and Cost Efficiencies: A Panel-Data Stochastic-Frontier Analysis of Real Estate Investment Trusts

This paper extends the existing research on real estate investment trust (REIT) operating efficiencies. We estimate a stochastic-frontier panel-data model specifying a translog cost function, covering 1995 to 2003. The results disagree with previous research in that we find little evidence of scale economies and some evidence of scale diseconomies. Moreover, we also generally find smaller inefficiencies than those shown by other REIT studies. Contrary to previous research, the results also show that self-management of a REIT associates with more inefficiency when we measure output with assets. When we use revenue to measure output, selfmanagement associates with less inefficiency. Also contrary with previous research, higher leverage associates with more efficiency. The results further suggest that inefficiency increases over time in three of our four specifications.

Cost Improvements, Returns to Scale, and Cost Inefficiencies for Real Estate Investment Trusts

This paper extends the existing research on real estate investment trust (REIT) operating efficiencies. We estimate stochastic-frontier, panel-data models specifying a translog cost function. The specified model updates the cost frontier with new information as it becomes available over time. The model can identify frontier cost improvements, returns to scale, and cost inefficiencies over time. The results disagree with most previous research in that we find no evidence of scale economies and some evidence of scale diseconomies. Moreover, we also generally find smaller inefficiencies than those shown by other REIT studies. Contrary to previous research, higher leverage associates with more efficiency.

Concentración y centralización del capital agrario en la región pampeana : El caso de los grandes pooles de siembra

El objetivo de este trabajo es juzgar las potencialidades del proceso de concentración del capital agrario a partir del caso de los llamados "grandes pooles de siembra". Para tal fin, se realiza un análisis de los proyectos de inversión y de producción de los pooles de siembra constituidos como Fondos Comunes Cerrados de Inversión y como Fideicomisos Financieros. Asimismo, se realiza un estudio en profundidad del caso del principal administrador de grandes pooles de siembra, la empresa Cazenave y Asociados. Se concluye que la producción agraria pampeana continúa siendo un espacio hostil para la acumulación de los capitales más concentrados de la economía.

Concentración y centralización del capital agrario en la región pampeana : El caso de los grandes pooles de siembra

El objetivo de este trabajo es juzgar las potencialidades del proceso de concentración del capital agrario a partir del caso de los llamados "grandes pooles de siembra". Para tal fin, se realiza un análisis de los proyectos de inversión y de producción de los pooles de siembra constituidos como Fondos Comunes Cerrados de Inversión y como Fideicomisos Financieros. Asimismo, se realiza un estudio en profundidad del caso del principal administrador de grandes pooles de siembra, la empresa Cazenave y Asociados. Se concluye que la producción agraria pampeana continúa siendo un espacio hostil para la acumulación de los capitales más concentrados de la economía.

Concentración y centralización del capital agrario en la región pampeana : El caso de los grandes pooles de siembra

El objetivo de este trabajo es juzgar las potencialidades del proceso de concentración del capital agrario a partir del caso de los llamados "grandes pooles de siembra". Para tal fin, se realiza un análisis de los proyectos de inversión y de producción de los pooles de siembra constituidos como Fondos Comunes Cerrados de Inversión y como Fideicomisos Financieros. Asimismo, se realiza un estudio en profundidad del caso del principal administrador de grandes pooles de siembra, la empresa Cazenave y Asociados. Se concluye que la producción agraria pampeana continúa siendo un espacio hostil para la acumulación de los capitales más concentrados de la economía.

Concentración y centralización del capital agrario en la región pampeana : El caso de los grandes pooles de siembra

El objetivo de este trabajo es juzgar las potencialidades del proceso de concentración del capital agrario a partir del caso de los llamados "grandes pooles de siembra". Para tal fin, se realiza un análisis de los proyectos de inversión y de producción de los pooles de siembra constituidos como Fondos Comunes Cerrados de Inversión y como Fideicomisos Financieros. Asimismo, se realiza un estudio en profundidad del caso del principal administrador de grandes pooles de siembra, la empresa Cazenave y Asociados. Se concluye que la producción agraria pampeana continúa siendo un espacio hostil para la acumulación de los capitales más concentrados de la economía.

Rhetorical purpose and the use of definitions as a coherence device in scientific communication

Se analiza la función de las definiciones en los textos científicos como elemento esencial para crear coherencia y dotar de comprensibilidad al texto. Se presentan varios ejemplos en textos de divulgación y en artículos dirigidos a pares.

A study on the inclusion of forest canopy morphology data in numerical simulations for the purpose of wind resource assessment

A series of numerical simulations of the flow over a forest stand have been conducted using two different turbulence closure models along with various levels of canopy morphology data. Simulations have been validated against Stereoscopic Particle Image Velocimetry measurements from a wind tunnel study using one hundred architectural model trees, the porosities of which have been assessed using a photographic technique. It has been found that an accurate assessment of the porosity of the canopy, and specifically the variability with height, improves simulation quality regardless of the turbulence closure model used or the level of canopy geometry included. The observed flow field and recovery of the wake is in line with characteristic canopy flows published in the literature and it was found that the shear stress transport turbulence model was best able to capture this detail numerically.

A General Purpose Configurable Controller for Indoors and Outdoors GPS-Denied Navigation for Multirotor Unmanned Aerial Vehicles

This research on odometry based GPS-denied navigation on multirotor Unmanned Aerial Vehicles is focused among the interactions between the odometry sensors and the navigation controller. More precisely, we present a controller architecture that allows to specify a speed specified flight envelope where the quality of the odometry measurements is guaranteed. The controller utilizes a simple point mass kinematic model, described by a set of configurable parameters, to generate a complying speed plan. For experimental testing, we have used down-facing camera optical-flow as odometry measurement. This work is a continuation of prior research to outdoors environments using an AR Drone 2.0 vehicle, as it provides reliable optical flow on a wide range of flying conditions and floor textures. Our experiments show that the architecture is realiable for outdoors flight on altitudes lower than 9 m. A prior version of our code was utilized to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012. The code will be released as an open-source ROS stack hosted on GitHub.

A General Purpose Configurable Navigation Controller for Micro Aerial Multirotor Vehicles

In this paper, we consider the problem of autonomous navigation of multirotor platforms in GPS-denied environments. The focus of this work is on safe navigation based on unperfect odometry measurements, such as on-board optical flow measurements. The multirotor platform is modeled as a flying object with specific kinematic constraints that must be taken into account in order to obtain successful results. A navigation controller is proposed featuring a set of configurable parameters that allow, for instance, to have a configuration setup for fast trajectory following, and another to soften the control laws and make the vehicle navigation more precise and slow whenever necessary. The proposed controller has been successfully implemented in two different multirotor platforms with similar sensoring capabilities showing the openness and tolerance of the approach. This research is focused around the Computer Vision Group's objective of applying multirotor vehicles to civilian service applications. The presented work was implemented to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012, gaining two awards: the Special Award on "Best Automatic Performance - IMAV 2012" and the second overall prize in the participating category "Indoor Flight Dynamics - Rotary Wing MAV". Most of the code related to the present work is available as two open-source projects hosted in GitHub.

Sematech: Purpose and Performance

In previous research, we have found a steep learning curve in the production of semiconductors. We estimated that most production knowledge remains internal to the firm, but that a significant fraction “spills over” to other firms. The existence of such spillovers may justify government actions to stimulate research on semiconductor manufacturing technology. The fact that not all production knowledge spills over, meanwhile, creates opportunities for firms to form joint ventures and slide down their learning curves more efficiently. With these considerations in mind, in 1987 14 leading U.S. semiconductor producers, with the assistance of the U.S. government in the form of $100 million in annual subsidies, formed a research and development (R&D) consortium called Sematech. In previous research, we estimated that Sematech has induced its member firms to lower their R&D spending. This may reflect more sharing and less duplication of research, i.e., more research being done with each R&D dollar. If this is the case, then Sematech members may wish to replace any funding withdrawn by the U.S. government. This in turn would imply that the U.S. government’s contributions to Sematech do not induce more semiconductor research than would otherwise occur.

A Schistosoma mansoni fatty acid-binding protein, Sm14, is the potential basis of a dual-purpose anti-helminth vaccine.

Molecular cloning of components of protective antigenic preparations has suggested that related parasite fatty acid-binding proteins could form the basis of the protective immune crossreactivity between the parasitic trematode worms Fasciola hepatica and Schistosoma mansoni. Molecular models of the two parasite proteins showed that both molecules adopt the same basic three-dimensional structure, consisting of a barrel-shaped molecule formed by 10 antiparallel beta-pleated strands joined by short loops, and revealed the likely presence of crossreactive, discontinuous epitopes principally derived from amino acids in the C-terminal portions of the molecules. A recombinant form of the S. mansoni antigen, rSm14, protected outbred Swiss mice by up to 67% against challenge with S. mansoni cercariae in the absence of adjuvant and without provoking any observable autoimmune response. The same antigen also provided complete protection against challenge with F. hepatica metacercariae in the same animal model. The results suggest that it may be possible to produce a single vaccine that would be effective against at least two parasites, F. hepatica and S. mansoni, of veterinary and human importance, respectively.