Deep K_s-near-infrared Surface Photometry of 80 Dwarf Irregular Galaxies in the Local Volume

We present deep near-infrared (K_s) images and surface photometry for 80 dwarf irregular galaxies (dIs) within ~5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies

The developmental dynamics of terrorist organizations

We identify robust statistical patterns in the frequency and severity of violent attacks by terrorist organizations as they grow and age. Using group-level static and dynamic analyses of terrorist events worldwide from 1968-2008 and a simulation model of organizational dynamics, we show that the production of violent events tends to accelerate with increasing size and experience. This coupling of frequency, experience and size arises from a fundamental positive feedback loop in which attacks lead to growth which leads to increased production of new attacks. In contrast, event severity is independent of both size and experience. Thus larger, more experienced organizations are more deadly because they attack more frequently, not because their attacks are more deadly, and large events are equally likely to come from large and small organizations. These results hold across political ideologies and time, suggesting that the frequency and severity of terrorism may be constrained by fundamental processes.Comment: 28 pages, 8 figures, 4 tables, supplementary materia

Relational Contracts and Organizational Capabilities

A large literature identifies unique organizational capabilities as a potent source of competitive advantage, yet our knowledge of why capabilities fail to diffuse more rapidly—particularly in situations in which competitors apparently have strong incentives to adopt them and a well-developed understanding of how they work—remains incomplete. In this paper we suggest that competitively significant capabilities often rest on managerial practices that in turn rely on relational contracts (i.e., informal agreements sustained by the shadow of the future). We argue that one of the reasons these practices may be difficult to copy is that effective relational contracts must solve the twin problems of credibility and clarity and that although credibility might, in principle, be instantly acquired, clarity may take time to develop and may interact with credibility in complex ways so that relational contracts may often be difficult to build

Unraveling the Historical Economies of Scale and Learning Effects for Desalination Technologies

As a technology develops and matures, both economies of scale and the lessons learned through experience drive down the cost over time. This article analyzes and separates the effects of economies of scale and learning through experience on historical cost reductions for three mature desalination technologies: multi‐effect distillation (MED), multi‐stage flash (MSF) distillation, and reverse osmosis (RO). The analysis suggests that learning has been the dominant driver for cost reductions, with learning rates of 23%, 30%, and 12% for MED, MSF, and RO, respectively, when the effects of scale are removed. The highest influence of economies of scale is found for MED, with an exponential scale coefficient of 0.71 and the largest difference between a traditional or scale‐free estimation of the learning rate. MSF and RO showed smaller differences between the traditional and de‐scaled learning rates (only 3%), pointing at learning as the main factor driving their historical cost reductions. However, a trend break observed over the last 10 years mirrors an exhaustion of the potential for technical improvements, as well as an increasing complexity and nonlinearity of the factors influencing the systems' cost. The findings provide useful data and insights for integrated and economic modeling frameworks, while providing guidance to prevent overestimations of the learning effect due to the confounding influence of economies of scale effects associated to historical unit upscaling processes

Code Reuse in Open Source Software

Code reuse is a form of knowledge reuse in software development that is fundamental to innovation in many fields. However, to date there has been no systematic investigation of code reuse in open source software projects. This study uses quantitative and qualitative data gathered from a sample of six open source software projects to explore two sets of research questions derived from the literature on software reuse in firms and open source software development. We find that code reuse is extensive across the sample and that open source software developers, much like developers in firms, apply tools that lower their search costs for knowledge and code, assess the quality of software components, and have incentives to reuse code. Open source software developers reuse code because they want to integrate functionality quickly, because they want to write preferred code, because they operate under limited resources in terms of time and skills, and because they can mitigate development costs through code reuse

Human Resources and the Resource Based View of the Firm

The resource-based view (RBV) of the firm has influenced the field of strategic human resource management (SHRM) in a number of ways. This paper explores the impact of the RBV on the theoretical and empirical development of SHRM. It explores how the fields of strategy and SHRM are beginning to converge around a number of issues, and proposes a number of implications of this convergence

Determinación de la capacidad de regulación hídrica de un Typic Hapludands mediante las curvas de retención de humedad y la modelación de sus propiedades hidrofísicas.

(Eng) In the watershed Centella , located in the upper river basin of the Dagua - Valle del Cauca, in nine farms with association coffee - banana, coffee - guamo, cane panelera and pastures, the water regulation capacity of the soil was studied by means of humidity retention curves obtained in the laboratory and by modeling its hydrophysical properties in Hydrus 2D. Properties such as texture, bulk density, porosity, organic matter, hydraulic conductivity, infiltration and humidity were determined. Subsequently, moisture retention curves were simulated using the hydraulic models of Van Genuchten, Brooks and Corey, Van Genuchten modified and Kosugi, evaluating the average errors and the dispersion of the data. Agreed to the results it is possible to point out that the soil under study has a high capacity for moisture retention ( > 18%), consequence of the high content of clays ( > 41%) and organic matter ( > 5%), characteristics of the Andisols of the Valle del Cauca. Finally, the best fitting model was compared statistically with the data of the curves obtained in the laboratory, finding that Van Genuchten and Van Genuchten models modified, are the most appropriate for obtaining the retention curves from the hydrophysical properties since they presented a lower mean error (ME) with a value not higher than -0.11 cm 3 / cm 3 and a value of the square root of the mean square error (RMSE) less than 0.11 cm 3 / cm 3 .(Spa) En la microcuenca Centella, ubicada en la cuenca alta del río Dagua - Valle del Cauca, en nueve fincas con asociación café – pláta - no, café - guamo, caña panelera y pastos, se estudió la capacidad de regulación hídrica del suelo mediante curvas de retención de humedad obtenidas en laboratorio y por modelación de sus propiedades hidrofísicas, en Hydrus 2D. Se determin ó textura, densidad aparente, porosidad, materia orgánica, conductividad hidr áulica, infiltración y humedad del suelo . Posteriormente, se simularon las curvas de retención de humedad mediante los modelos hidráulicos de Van Genuchten, Brooks y Corey, Van Genuchten modificado y Kosugi, evaluando los errores medios y la dispersión de los datos. De acuerdo a los resultados es posible señalar que el suelo en estudio tiene una alta capacidad de retención de humedad ( > 18 % ), debido a los altos contenidos de arcilla ( > 41 %) y materia or - gánica ( > 5%) , característico de los Andisoles presentes en el Valle del Cauca. Finalmente, se comparó estadísticamente el modelo de mejor ajuste con los datos de las curvas obtenidas en laboratorio, encontrando que los modelos Van Genuchten y Van Genuchten modificado, son los más apropiados para la obtención de las curvas de retención a partir de propiedades hidrofísicas dado que pre - sentaron un menor error medio (ME) con un valor no superior a -0.11 cm 3 /cm 3 y un valor de la raíz cuadrada del error cuadrático medio (RMSE) menor de 0.11 cm 3 /cm 3

THE ROLE OF INTERDEPENDENCE IN THE MICRO-FOUNDATIONS OF ORGANIZATION DESIGN: TASK, GOAL, AND KNOWLEDGE INTERDEPENDENCE

Interdependence is a core concept in organization design, yet one that has remained consistently understudied. Current notions of interdependence remain rooted in seminal works, produced at a time when managers’ near-perfect understanding of the task at hand drove the organization design process. In this context, task interdependence was rightly assumed to be exogenously determined by characteristics of the work and the technology. We no longer live in that world, yet our view of interdependence has remained exceedingly task-centric and our treatment of interdependence overly deterministic. As organizations face increasingly unpredictable workstreams and workers co-design the organization alongside managers, our field requires a more comprehensive toolbox that incorporates aspects of agent-based interdependence. In this paper, we synthesize research in organization design, organizational behavior, and other related literatures to examine three types of interdependence that characterize organizations’ workflows: task, goal, and knowledge interdependence. We offer clear definitions for each construct, analyze how each arises endogenously in the design process, explore their interrelations, and pose questions to guide future research