U-curve: A branch-and-bound optimization algorithm for U-shaped cost functions on Boolean lattices applied to the feature selection problem

This paper presents the formulation of a combinatorial optimization problem with the following characteristics: (i) the search space is the power set of a finite set structured as a Boolean lattice; (ii) the cost function forms a U-shaped curve when applied to any lattice chain. This formulation applies for feature selection in the context of pattern recognition. The known approaches for this problem are branch-and-bound algorithms and heuristics that explore partially the search space. Branch-and-bound algorithms are equivalent to the full search, while heuristics are not. This paper presents a branch-and-bound algorithm that differs from the others known by exploring the lattice structure and the U-shaped chain curves of the search space. The main contribution of this paper is the architecture of this algorithm that is based on the representation and exploration of the search space by new lattice properties proven here. Several experiments, with well known public data, indicate the superiority of the proposed method to the sequential floating forward selection (SFFS), which is a popular heuristic that gives good results in very short computational time. In all experiments, the proposed method got better or equal results in similar or even smaller computational time. (C) 2009 Elsevier Ltd. All rights reserved.

The value of a saved tree : The lifecycle of CO2-emissions associated with the combination of printing paper and electricity production of wood in the U.S. and Sweden

The pulp- and paper production is a very energy intensive industry sector. Both Sweden and the U.S. are major pulpandpaper producers. This report examines the energy and the CO2-emission connected with the pulp- and paperindustry for the two countries from a lifecycle perspective.New technologies make it possible to increase the electricity production in the integrated pulp- andpaper mill through black liquor gasification and a combined cycle (BLGCC). That way, the mill canproduce excess electricity, which can be sold and replace electricity produced in power plants. In thisprocess the by-products that are formed at the pulp-making process is used as fuel to produce electricity.In pulp- and paper mills today the technology for generating energy from the by-product in aTomlinson boiler is not as efficient as it could be compared to the BLGCC technology. Scenarios havebeen designed to investigate the results from using the BLGCC technique using a life cycle analysis.Two scenarios are being represented by a 1994 mill in the U.S. and a 1994 mill in Sweden.The scenariosare based on the average energy intensity of pulp- and paper mills as operating in 1994 in the U.S.and Sweden respectively. The two other scenarios are constituted by a »reference mill« in the U.S. andSweden using state-of-the-art technology. We investigate the impact of varying recycling rates and totalenergy use and CO2-emissions from the production of printing and writing paper. To economize withthe wood and that way save trees, we can use the trees that are replaced by recycling in a biomassgasification combined cycle (BIGCC) to produce electricity in a power station. This produces extra electricitywith a lower CO2 intensity than electricity generated by, for example, coal-fired power plants.The lifecycle analysis in this thesis also includes the use of waste treatment in the paper lifecycle. Both Sweden and theU.S. are countries that recycle paper. Still there is a lot of paper waste, this paper is a part of the countries municipalsolid waste (MSW). A lot of the MSW is landfilled, but parts of it are incinerated to extract electricity. The thesis hasdesigned special scenarios for the use of MSW in the lifecycle analysis.This report is studying and comparing two different countries and two different efficiencies on theBLGCC in four different scenarios. This gives a wide survey and points to essential parameters to specificallyreflect on, when making assumptions in a lifecycle analysis. The report shows that there arethree key parameters that have to be carefully considered when making a lifecycle analysis of wood inan energy and CO2-emission perspective in the pulp- and paper mill in the U.S. and in Sweden. First,there is the energy efficiency in the pulp- and paper mill, then the efficiency of the BLGCC and last theCO2 intensity of the electricity displaced by BIGCC or BLGCC generatedelectricity. It also show that with the current technology that we havetoday, it is possible to produce CO2 free paper with a waste paper amountup to 30%. The thesis discusses the system boundaries and the assumptions.Further and more detailed research, including amongst others thesystem boundaries and forestry, is recommended for more specificanswers.

The determinants of internationalstudent mobility : An empirical study on U.S. Data

The increase in foreign students in countries such as the US, the UK and Francesuggests that the international ‘education industry’ is growing in importance. Thepurpose of this paper is to investigate the empirical determinants of internationalstudent mobility. A secondary purpose is to give tentative policy suggestions to hostcountry, source country and also to provide some recommendations to students whowant to study abroad. Using pooled cross-sectional time series data for the US overthe time period 1993-2006, we estimate an econometric model of enrolment rates offoreign students in the US. Our results suggest that tuition fees, US federal support ofeducation, and the size of the ‘young’ generation of source countries have asignificant influence on international student mobility. We also consider other factorsthat may be relevant in this context.

LEARNING STUDY: ROZVOJ ŠKOLY SKRZE KOLEGIÁLNÍ UČENÍ UČITELŮ : Learning study: school development through collegial learning of teachers

The aim of this article is to describe how the Learning Study method (LS) was implemented in a Swedish upper secondary school, as well as how the principals and the teachers involved perceived this to affect teaching at, and the development of, the school. It is an empirical study that was conducted as an action research project over a period of three years. The project to implement the LS method was based on the assumption that proper training is the result of collegial activity that occurs when teachers learn from each other. The teachers in this study were, in general, positive about using the LS method. It created opportunities to meet and talk about teaching skills, developed better professional relationships between colleagues, and offered a systematic method for planning, implementing and monitoring teaching. However, working together requires that time be set aside to allow for implementation of the LS method. This is crucial, as the LS method is a rather expensive way to make school development work. This places heavy demands on principals to create the necessary conditions for the implementation of the LS method.

Candidate Quality and Voter Response in U.S. House Elections

We propose and test the implications of a two-dimensional concept of candidate quality in U.S. House elections. Strategic quality is composed of the skills and resources necessary to wage an effective campaign; personal quality is composed of the characteristics most ordinary citizens value in their leaders and representatives, such as personal integrity and dedication to public service. We employ district informants in studies of the 1998 and 2002 congressional elections to measure these qualities in candidates, and we merge mass survey data with the district informant indicators to assess constituents’ awareness and evaluation of House candidates, and voting choice. We find that awareness tends to be responsive to candidates’ strategic quality, and that incumbent evaluation is remarkably responsive to variation in personal quality, even taking into account the quality of challenger emergence. These and other findings appear to support a more positive view of citizen capacity than is common in the congressional elections literature, especially in light of the electoral security of House incumbents.

Stock Markets and Household Wealth: Can a Stock Market Crash Cause a Recession in The U.S. Economy?

Stock market wealth effects on the level of consumption in the United States economy have been constantly debated; there is evidence for arguments for and against its prominence and its symmetry. This paper seeks to investigate the strength of its negative effect by creating models to analyze unexpected shocks to the Standard and Poor's 500 index. First, a transmission mechanism between the stock market and GDP is established through the use of second-order vector autoregressive models. Following which, theory from the life cycle model and adaptations of previous researchers' models are used to create a structural model. This paper finds that stock market wealth effects are small, but important to consider, especially if markets are overpriced; this claim is corroborated by evidence from simulation of 'alternative scenarios' and the historical experiences of 1987 and 2001.

Incumbency Reconsidered: Prospects, Strategic Entry, and Incumbent Quality in U.S. House Elections

Efforts to estimate the magnitude of the incumbency effect in U.S. House elections and assess its political meaning have been complicated by two omitted-variables problems. First, in the absence of an adequate measure of incumbent prospects, estimates of the magnitude of the incumbency effect fail to control for selection effects associated with the decision incumbents make about whether to run for reelection. Strategic incumbents enter races they think they can win and withdraw when they expect to lose. The consequence is an upward bias in estimates of incumbents’ electoral advantages. Second, the normative implications of high reelection rates cannot be assessed without measuring incumbent quality, since a possible explanation for their electoral success is that incumbents are of high quality and doing a good job. We propose a strategy for measuring incumbent prospects and quality, demonstrate the strategic nature of incumbent and challenger entry, re-estimate the incumbency effect, and show that incumbent quality has an impact on electoral outcomes. Our conclusion is that incumbents’ advantages in House elections have been over estimated while the positive basis of incumbent safety is typically under appreciated.

September 2007: U.S. Constitution Day

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Further investigation of the uncertain trend in U.S. GDP

The presence of deterministic or stochastic trend in U.S. GDP has been a continuing debate in the literature of macroeconomics. Ben-David and Papell (1995) found evindence in favor of trend stationarity using the secular sample of Maddison (1995). More recently, Murray and Nelson (2000) correctly criticized this nding arguing that the Maddison data are plagued with additive outliers (AO), which bias inference towards stationarity. Hence, they propose to set the secular sample aside and conduct inference using a more homogeneous but shorter time-span post-WWII sample. In this paper we re-visit the Maddison data by employing a test that is robust against AO s. Our results suggest the U.S. GDP can be modeled as a trend stationary process.

The asymmetric behavior of the U.S public debt

Our main goal in this paper was to measure how e¢ cient is risk sharing between countries. In order to do so, we have used a international risk sharIn this paper we re-analyze the question of the U.S. public debt sustainability by using a quantile autoregression model. This modeling allows for testing whether the behavior of U.S. public debt is asymmetric or not. Our results provide evidence of a band of sustainability. Outside this band, the U.S. public debt is unsustainable. We also nd scal policy to be adequate in the sense that occasional episodes in which the public debt moves out of the band do not pose a threat to long run sustainability.

The asymmetric behavior of the U.S. public debt

In this paper we re-analyze the question of the U.S. public debt sustainability by using a quantile autoregression model. This modeling allows for testing whether the behavior of U.S. public debt is asymmetric or not. Our results provide evidence of a band of sustainability. Outside this band, the U.S. public debt is unsustainable. We also find fiscal policy to be adequate in the sense that occasional episodes in which the public debt moves out of the band do not pose a threat to long run sustainability.

O contrato de gestão em busca de um modelo para empresas de obras especiais - EMPROE-U.E.E

The present dissertation target, is to analyze the application viability of the administration contract at the Public Administration in a general and concomitantly order, to simulate a contract of Administration for a Special-Works Enterprise - Economical State Unity - EMPROE - U.E.E , pointed out the importance of this, for the immediate Political-Social and economical situation that Angola hindes on the domain of Public-Works and Urbanism taking account the theoretical developed on the following chapters. At the first chapter, seeked to supply brief datas about what have been done at several sectors ofthe angolan economy. At the second chapter, particularizedly describes the historical evolution of the Manageral ambience from Angola. At the third chapter we did mention to the concepts and thecnical aspects of the Strategical Administration and the concepts, origins, and the Administration characteristics by Objectives. The fourth chapter handles about the origin of the Administration Contracts, according of his historic/concept at the evolution agreement procedures. At the fifth chapter doing some considerations about the Brazilian Experience of Administraion contracts, particularizing cases from C.V.R.D. , from Petrobrás and the implantation skill of the Administration contracts for the State Govemments of São Paulo. At the sixth chapter allude to the American Experince in Administration contracts had the flexibility and the Institute of "W AIVER" as reference. At the seventh chapter dials of the Angolan Experience at the Administration contracts, just as reference to the Beers Nacional Enterprises - CERV AL. The eighth presents a contract simulation of Administration between the EMPROE-U.E.E and the MINOPU, focalizing the Strategical function, mission and the luridical instruments, according to a specific model. The ninth and the last one chapter do some inherences to the analysis of the contracts viability of Administration and some suggestions for the Enterprise as a conclusion.

Fuel ethanol price drivers in the Atlantic basin : Brazil & the U.S. traders perspectives

Como a oportunidade de exportação de etanol combustível é muito recente, o agronegócio carece de literatura para formação de gestores e estrategistas. Este trabalho tem como objetivo descrever o mecanismo de formação de preços de etanol tanto no Brasil como nos Estados Unidos da America. Decupei as variáveis que impactam na formação de preços, custo de produção de etanol de cana-de-açúcar, custo da logística e desidratação no Caribe, custo do etanol de milho e fiz algumas análises de cenários de formação de preços das principais variáveis e consegui organizar este conhecimento em um gráfico que contém no eixo superior preço do etanol hidratado na usina no Brasil e no eixo inferior o preço do bushel de milho em Chicago cujas interceções nas retas da taxa do dólar e do preço do gás natural, fornecem no eixo Y o preço do produto no porto de Nova York, ficando uma visualização simples das possibilidades da janela de exportação. A metodologia permite assumir diferentes cenários de oferta, demanda e preços e estabelecer diferentes estratégias de comercialização.