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Basic Models (basic + models)
Selected AbstractsTHE ECONOMICS OF HOMELAND SECURITY EXPENDITURES: FOUNDATIONAL EXPECTED COST-EFFECTIVENESS APPROACHESCONTEMPORARY ECONOMIC POLICY, Issue 1 2007SCOTT FARROW While most economists expect some marginal conditions to result from basic expected value models involving government expenditures and homeland security investments, such models are not readily found in the literature. The article presents six basic models that all incorporate uncertainty; they also capture various problems involving technological limits, behavioral interactions, false negatives and false positives, and decision making with uncertainty and irreversibility. Recent reviews of homeland security programs by the U.S. Government Accountability Office are used to illustrate the relevance of the models.(JEL H100) [source] Plasma Edge Physics with B2-EireneCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-2 2006R. Schneider Abstract The B2-Eirene code package was developed to give better insight into the physics in the scrape-off layer (SOL), which is defined as the region of open field-lines intersecting walls. The SOL is characterised by the competition of parallel and perpendicular transport defining by this a 2D system. The description of the plasma-wall interaction due to the existence of walls and atomic processes are necessary ingredients for an understanding of the scrape-off layer. This paper concentrates on understanding the basic physics by combining the results of the code with experiments and analytical models or estimates. This work will mainly focus on divertor tokamaks, but most of the arguments and principles can be easily adapted also to other concepts like island divertors in stellarators or limiter devices. The paper presents the basic equations for the plasma transport and the basic models for the neutral transport. This defines the basic ingredients for the SOLPS (Scrape-Off Layer Plasma Simulator) code package. A first level of understanding is approached for pure hydrogenic plasmas based both on simple models and simulations with B2-Eirene neglecting drifts and currents. The influence of neutral transport on the different operation regimes is here the main topic. This will finish with time-dependent phenomena for the pure plasma, so-called Edge Localised Modes (ELMs). Then, the influence of impurities on the SOL plasma is discussed. For the understanding of impurity physics in the SOL one needs a rather complex combination of different aspects. The impurity production process has to be understood, then the effects of impurities in terms of radiation losses have to be included and finally impurity transport is necessary. This will be introduced with rising complexity starting with simple estimates, analysing then the detailed parallel force balance and the flow pattern of impurities. Using this, impurity compression and radiation instabilities will be studied. This part ends, combining all the elements introduced before, with specific, detailed results from different machines. Then, the effect of drifts and currents is introduced and their consequences presented. Finally, some work on deriving scaling laws for the anomalous turbulent transport based on automatic edge transport code fitting procedures will be described. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] GENETICS AND RECENT HUMAN EVOLUTIONEVOLUTION, Issue 7 2007Alan R. Templeton Starting with "mitochondrial Eve" in 1987, genetics has played an increasingly important role in studies of the last two million years of human evolution. It initially appeared that genetic data resolved the basic models of recent human evolution in favor of the "out-of-Africa replacement" hypothesis in which anatomically modern humans evolved in Africa about 150,000 years ago, started to spread throughout the world about 100,000 years ago, and subsequently drove to complete genetic extinction (replacement) all other human populations in Eurasia. Unfortunately, many of the genetic studies on recent human evolution have suffered from scientific flaws, including misrepresenting the models of recent human evolution, focusing upon hypothesis compatibility rather than hypothesis testing, committing the ecological fallacy, and failing to consider a broader array of alternative hypotheses. Once these flaws are corrected, there is actually little genetic support for the out-of-Africa replacement hypothesis. Indeed, when genetic data are used in a hypothesis-testing framework, the out-of-Africa replacement hypothesis is strongly rejected. The model of recent human evolution that emerges from a statistical hypothesis-testing framework does not correspond to any of the traditional models of human evolution, but it is compatible with fossil and archaeological data. These studies also reveal that any one gene or DNA region captures only a small part of human evolutionary history, so multilocus studies are essential. As more and more loci became available, genetics will undoubtedly offer additional insights and resolutions of human evolution. [source] An integrated, finite element-based process model for the analysis of flow, heat transfer, and solidification in a continuous slab casterINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2003C. H. Moon Abstract An integrated, finite element-based process model is presented for the prediction of full three-dimensional flow, heat transfer, and solidification occurring in a continuous caster. Described in detail are the basic models for the analysis of turbulent flow and heat transfer in the liquid steel zone, in the zone of mixture of the liquid steel and solidified steel, and in the solidified zone. Then, the models are integrated to form a process model which can take into account the strong interdependence between the heat transfer behaviour and the flow behaviour. The capability of the process model to reveal the detailed aspects of turbulent flow, heat transfer, and solidification occurring in a continuous caster is demonstrated through a series of process simulations. Copyright © 2003 John Wiley & Sons, Ltd. [source] Basic scheduling problems with raw material constraintsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 6 2005Alexander Grigoriev Abstract One of the achievements of scheduling theory is its contribution to practical applications in industrial settings. In particular, taking finiteness of the available production capacity explicitly into account, has been a major improvement of standard practice. Availability of raw materials, however, which is another important constraint in practice, has been largely disregarded in scheduling theory. This paper considers basic models for scheduling problems in contemporary manufacturing settings where raw material availability is of critical importance. We explore single scheduling machine problems, mostly with unit or all equal processing times, and Lmax and Cmax objectives. We present polynomial time algorithms, complexity and approximation results, and computational experiments. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005. [source] The New Economic Sociology of Prices: An Analysis Inspired by the Austrian School of EconomicsAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2010Renaud Fillieule The new economic sociology includes some reference studies on the sociology of prices. They have not until now been studied by economists, and this article attempts to fill that gap by offering a detailed analysis, inspired by the Austrian School of Economics, of their object and approach. We first show that, from a theoretical point of view, the explanations advanced by these sociologists are based implicitly on basic models of economics, such as the "law of supply and demand" and the "law of costs," and that they cannot therefore replace economic explanations of prices. Secondly, from a methodological point of view, these studies are based on field surveys that provide concrete information on certain markets but they lose sight of an aspect that is fundamental to the Austrian School, the interdependence of prices in different markets. And when this interdependence is taken into account, namely, in the case of the relationship between cost and price, the causal link postulated by sociologists goes from cost to price when Austrian economists argue that it goes in the opposite direction. [source] The Office of CommunicationsPRESIDENTIAL STUDIES QUARTERLY, Issue 4 2001MARTHA JOYNT KUMAR The Office of Communications is front and center in the White House effort to publicize the president and his policies. The importance of presidential communications can be seen in the manner in which the topic drives the agenda of daily staff meetings, the size of the commitment to it of White House and administration resources and people, and the way the function has insinuated itself into the operations of almost every White House office. While most White House offices are defined by the functions that come with the unit, the communications director's position is defined by his or her relationships with officials working inside and outside of the White House, including the president, the chief of staff, the press secretary, and officials in departments and agencies. There are three basic models for communications directors as they manage their operations: advocate with the press, strategist and planner, and events coordinator. At its minimum, the job entails events management, but its larger role is defining the message and strategic plan of a presidency. [source] | ||||||||||