On maxitive integration

A functional is said to be maxitive if it commutes with the (pointwise) supremum operation. Such functionals find application in particular in decision theory and related fields. In the present paper, maxitive functionals are characterized as integrals with respect to maxitive measures (also known as possibility measures or idempotent measures). These maxitive integrals are then compared with the usual additive and nonadditive integrals on the basis of some important properties, such as convexity, subadditivity, and the law of iterated expectations

Transverse fracture properties of green wood and the anatomy of six temperate tree species

© Institute of Chartered Foresters, 2016. All rights reserved. The aim of this study was to investigate the effect of wood anatomy and density on the mechanics of fracture when wood is split in the radial-longitudinal (RL) and tangential-longitudinal (TL) fracture systems. The specific fracture energies (Gf, J m-2) of the trunk wood of six tree species were studied in the green state using double-edge notched tensile tests. The fracture surfaces were examined in both systems using Environmental Scanning Electron Microscopy (ESEM). Wood density and ray characteristics were also measured. The results showed that Gf in RL was greater than TL for five of the six species. In particular, the greatest degree of anisotropy was observed in Quercus robur L., and the lowest in Larix decidua Mill. ESEM micrographs of fractured specimens suggested reasons for the anisotropy and differences across tree species. In the RL system, fractures broke across rays, the walls of which unwound like tracheids in longitudinal-tangential (LT) and longitudinal-radial (LR) failure, producing a rough fracture surface which would absorb energy, whereas in the TL system, fractures often ran alongside rays

On the implementation of LIR: the case of simple linear regression with interval data

This paper considers the problem of simple linear regression with interval-censored data. That is, n pairs of intervals are observed instead of the n pairs of precise values for the two variables (dependent and independent). Each of these intervals is closed but possibly unbounded, and contains the corresponding (unobserved) value of the dependent or independent variable. The goal of the regression is to describe the relationship between (the precise values of) these two variables by means of a linear function. Likelihood-based Imprecise Regression (LIR) is a recently introduced, very general approach to regression for imprecisely observed quantities. The result of a LIR analysis is in general set-valued: it consists of all regression functions that cannot be excluded on the basis of likelihood inference. These regression functions are said to be undominated. Since the interval data can be unbounded, a robust regression method is necessary. Hence, we consider the robust LIR method based on the minimization of the residuals' quantiles. For this method, we prove that the set of all the intercept-slope pairs corresponding to the undominated regression functions is the union of finitely many polygons. We give an exact algorithm for determining this set (i.e., for determining the set-valued result of the robust LIR analysis), and show that it has worst-case time complexity O(n^3 log n). We have implemented this exact algorithm as part of the R package linLIR

Impact of the global crisis on the achievement of the MDGs in Latin America

Progress towards the MDGs is expected to slow as a consequence of the global economic downturn. This study applies an economy-wide framework to analyze the impact of the crisis on MDG achievement in six Latin American countries. It finds significant setbacks towards the goals and, in the case of the region’s low-income countries, the cost of achieving these would rise between 1.6 and 3.4 per cent of GDP per year between 2010 and 2015 as compared with a no-crisis scenario. The additional public spending would contribute to economic growth though not sufficiently for full recovery to pre-crisis growth.computable general equilibrium models, distribution, welfare and poverty, foreign aid, macroeconomic analyses of economic development

Liberalizing Trade, and its Impact on Poverty and Inequality in Nicaragua

The Doha Round of multilateral trade negotiations stalled in 2008 owing in no small degree to a lack of agreement on the terms of substantially reducing trade-distorting support for agricultural products and to what extent this would be beneficial to developing countries. Nicaragua presents an interesting case in point, being one of the poorest economies in Latin America with still a relatively large agricultural sector and high degrees of rural poverty. In 2005, the country signed a free trade agreement with the United States. A previous study showed that most welfare gains of this agreement for Nicaragua would potentially come from the increased market access for textiles and clothing exported to the United States. Under the agreement, the country stands to benefit much less from reducing tariffs on agricultural imports or agro-industrial export quotas. Since the United States is Nicaragua’s main trading partner, this raises the question whether further trade liberalization with all trading partners, including full elimination of all taxes and tariffs on agricultural production and trade, would be any more beneficial. Using a CGE model and a microsimulation methodology, this study shows that small welfare gains in terms of increased output and poverty reduction may be expected for Nicaragua under various scenarios of trade opening. At best, however, there would be a static gain in aggregate output of 1.5 percent as compared with the baseline scenario. This outcome would materialize only in a scenario of worldwide liberalization of trade in agricultural and non-agricultural products as this would yield relatively strong positive terms-of-trade effects for Nicaragua. Employment and real wage growth would contribute to poverty reduction, but only very modestly in a country with still widespread poverty. Most of these small gains would accrue to the rural poor. The analysis further shows that these gains tend to be smaller when using trade elasticity estimates based on country-specific data as compared with the much higher elasticities typically assumed by global trade models, including the Global Linkage model.Distorted incentives, agricultural and trade policy reforms, national agricultural development, Agricultural and Food Policy, International Relations/Trade, F13, F14, Q17, Q18,

A Non-Parametric Microsimulation Approach to Assess Changes in Inequality and Poverty

This paper presents a non-parametric microsimulation methodology for assessing the determinants of changes in income inequality and poverty. One great advantage of this method over alternatives is that it is not very demanding in terms of modelling labour supply and household behaviour while still providing a plausible link between changes in overall labour market conditions and the full household income distribution. The paper also shows how the method can be adapted to assess the poverty and inequality effects of changes in non-labour incomes (such as through a government transfer programme) and how it can be combined with economy-wide models.Non-parametric simulation methods; Computable General Equilibrium Models; Income Distribution; Employment, Unemployment, and Wages; Measurement and Analysis of Poverty; Effects of Welfare Programs; Supply and Demand for Labour; Segmented Labour Markets

Accidents in (0,2) Landau-Ginzburg theories

We study the role of accidental symmetries in two-dimensional (0,2) superconformal field theories obtained by RG flow from (0,2) Landau-Ginzburg theories. These accidental symmetries are ubiquitous, and, unlike in the case of (2,2) theories, their identification is key to correctly identifying the IR fixed point and its properties. We develop a number of tools that help to identify such accidental symmetries in the context of (0,2) Landau-Ginzburg models and provide a conjecture for a toric structure of the SCFT moduli space in a large class of models. We also give a self-contained discussion of aspects of (0,2) conformal perturbation theory.Comment: 37 pages; expanded conformal perturbation theory discussion in v2; fixed an accident in section 3.5 in v