Communities and regularities in the behavior of investment fund managers

We analyze a large microlevel dataset on the full daily portfolio holdings and exposures of 22 complex investment funds to shed light on the behavior of professional investment fund managers. We introduce a set of quantitative attributes that capture essential distinctive features of manager allocation strategies and behaviors. These characteristics include turnover, attitude toward hedging, portfolio concentration, and reaction to external events, such as changes in market conditions and flows of funds. We find the existence and stability of three main investment attitude profiles: conservative, reactive, and proactive. The conservative profile shows low turnover and resilience against external shocks; the reactive one is more prone to respond to market condition changes; and members of the proactive profile frequently adjust their portfolio allocations, but their behavior is less affected by market conditions. We find that exogenous shocks temporarily alter this configuration, but communities return to their original state once these external shocks have been absorbed and their effects vanish

Parâmetros para o manejo de irrigação da pupunheira no Vale do São Francisco.

O consumo de água e o coeficiente de cultura da pupuneira foram estimados do plantio até a quinta colheita de palmito, durante dois anos e três meses, em Juazeiro-BA. Os valores desses parâmetros aumentaram consideravelmente até o décimo terceiro mês após o plantio (primeira colheita), devido ao crescimento contínuo das plantas. Com os cortes realizados aproximadamente a cada três ou quatro meses, os valores apresentaram variações devido à redução do número de plantas por área

Assessment of Engineering Mechanics Instructional Multimedia in a Variety of Instructional Settings

Students from Ten Schools, Representing Seven Countries, Used Interactive Multimedia as a Part of their Engineering Statics Classes. the Software Consisted of Four Modules, Which Focused On: Mohr\u27s Circle; Centroid and Moment of Inertia; Stress Transformation; and Structural Analysis. the Students Completed On-Line Surveys About their Experience with the Software. Analysis of the Results Indicated that Students Rated their Knowledge of the Subject Matter Covered in the Software as Increasing Significantly as a Consequence of using the Software. However, This Increase Was Substantially More Pronounced for Students in U.S. Schools. Students Rated the Software as Significantly More Effective Than their Class Textbooks, And, Again, This Effect Was Substantially Stronger for Students in the U.S. the Analyses Also Indicated that the Software Differed Little in its Impact on Males Versus Females. Ratings on a Number of Additional Outcomes Were Consistently Positive with Respect to Student Opinions of the Software

Interactive Learning Tools: Animating Statics

Computer-Based Modules for Engineering Instruction Must Be Concise, Flexible, Educational and Engaging in Order to Effectively Supplement Traditional Classroom Teaching Tools. a Computer Example that Takes More Time Than a Chalkboard Presentation is Not Likely to Be Useful in Today\u27s Engineering Classroom. Flexible Navigation is Necessary So that the Instructor Can Quickly and Easily Respond to Student Questions. Useful Modules Must Also Improve Problem-Solving Skills or Clarify Troublesome Concepts in Order to Be Considered Worthy of Inclusion in the Limited Class Time Available. Finally, and Perhaps Most Importantly, Effective Computer-Based Modules Must Meet the Challenge of Holding the Student\u27s Attention. This Paper Focuses on the Development and Improvement of Computer-Based Interactive Modules for Statics Instruction. the Modules Were Created using an Animation Package (Flash®) So that Concepts Such as Sectioning of Trusses and the Generation of Shear and Moment Diagrams Can Be Presented in an Intuitive and Interactive Manner. the Modules Are Able to Represent Dynamic and Abstract Aspects of These Concepts in a Way that is Not Possible with Traditional Instructional Tools. the Paper Also Discusses the Use of Feedback from Instructors and Students to Improve the Interactivity and Scope of the Modules

Incorporating Web-Based Homework Problems in Engineering Dynamics

We are involved in a project funded by the Department of Education (FIPSE) which focuses on developing interactive software to improve the teaching and learning of engineering statics, dynamics, and mechanics of materials. This paper presents an overview of this project, discusses its objectives, and focuses on one particular aspect of the project.the use of web-based homework problems as assessment tools to evaluate student learning. The overall project includes creating, for all three engineering mechanics courses, the following web-based learning tools: (a) Animated theory modules, using Macromedia.s Flash development software, which display basic theory and example problems in an engaging, clear, and concise way; (b) Conceptual quizzes to evaluate student understanding of the theory; (c) Web-based homework problems to assess students. quantitative skills; (d) Other media elements, including streaming video mini-lectures over key topics, and video of real mechanisms and examples. The paper will give examples of web-based homework used in dynamics, discuss aspects of creating and using these, and give some results of student feedback from using these problems

Distribuicao de raizes de pupunha (Bactris gasipae Kunth.) irrigada em Latossolo Vermelho Amarelo.

A distribuicao da massa seca radicular da pupunha irrigada por sulcos em um latossolo vermelho amarelo de Petrolina-PE, foi analisada para se determinar a profundidade efetiva das raizes

Mud Loss Estimation using Machine Learning Approach

Lost circulation costs are a significant expense in drilling oil and gas wells. Drilling anywhere in the Rumaila field, one the world\u27s largest oilfields, requires penetrating the Dammam formation, which is notorious for lost circulation issues and thus a great source of information on lost circulation events. This paper presents a new, more precise model to predict lost circulation volumes, equivalent circulation density (ECD), and rate of penetration (ROP) in the Dammam formation. A larger data set, more systematic statistical approach, and a machine-learning algorithm have produced statistical models that give a better prediction of the lost circulation volumes, ECD, and ROP than the previous models for events. This paper presents the new model, validates the key elements impacting lost circulation in the Dammam formation, and compares the predicted outcomes to those from the older model. The work previously presented by Al-Hameedi et al. (http://www.onepetro.org, 2017a; http://www.AADE.org, 2017b) provided a platform for predicting the severity of lost circulation incidents in the Dammam formation. Using the new models, the predictions closely track actual field incidents of lost circulation. When new lost circulation events were compared with predictions from the old and new models, the new model presented a much tighter prediction of events. Three equations for optimizing operations were developed from these models focusing on the elements that have the highest degree of impact. The total flow area of the nozzles was determined to be a significant factor in the ROP model indicating that nozzle size should be chosen carefully to achieve optimal ROP. Good modeling of projected lost circulation events can assist in evaluating the effectiveness of new treatments for lost circulation. The Dammam formation is a significant source of lost circulation in a major oilfield and warrants evaluation of the effectiveness of lost circulation treatments. These techniques can be applied to other fields and formations to better understand the economic impact of lost circulation and evaluate the effectiveness of various lost circulation mitigation efforts

The Holst Spin Foam Model via Cubulations

Spin foam models are an attempt for a covariant, or path integral formulation of canonical loop quantum gravity. The construction of such models usually rely on the Plebanski formulation of general relativity as a constrained BF theory and is based on the discretization of the action on a simplicial triangulation, which may be viewed as an ultraviolet regulator. The triangulation dependence can be removed by means of group field theory techniques, which allows one to sum over all triangulations. The main tasks for these models are the correct quantum implementation of the Plebanski constraints, the existence of a semiclassical sector implementing additional "Regge-like" constraints arising from simplicial triangulations, and the definition of the physical inner product of loop quantum gravity via group field theory. Here we propose a new approach to tackle these issues stemming directly from the Holst action for general relativity, which is also a proper starting point for canonical loop quantum gravity. The discretization is performed by means of a "cubulation" of the manifold rather than a triangulation. We give a direct interpretation of the resulting spin foam model as a generating functional for the n-point functions on the physical Hilbert space at finite regulator. This paper focuses on ideas and tasks to be performed before the model can be taken seriously. However, our analysis reveals some interesting features of this model: first, the structure of its amplitudes differs from the standard spin foam models. Second, the tetrad n-point functions admit a "Wick-like" structure. Third, the restriction to simple representations does not automatically occur -- unless one makes use of the time gauge, just as in the classical theory.Comment: 25 pages, 1 figure; v3: published version. arXiv admin note: substantial text overlap with arXiv:0911.213

A new look at loop quantum gravity

I describe a possible perspective on the current state of loop quantum gravity, at the light of the developments of the last years. I point out that a theory is now available, having a well-defined background-independent kinematics and a dynamics allowing transition amplitudes to be computed explicitly in different regimes. I underline the fact that the dynamics can be given in terms of a simple vertex function, largely determined by locality, diffeomorphism invariance and local Lorentz invariance. I emphasize the importance of approximations. I list open problems.Comment: 15 pages, 5 figure