Will the U.S. productivity resurgence continue?

U.S. productivity growth has accelerated in recent years, despite a series of negative economic shocks. An analysis of the sources of this growth over the 1995-2003 period suggests that the production and use of information technology account for a large share of the gains. The authors project that during the next decade, private sector productivity growth will continue at a rate of 2.6 percent per year, a significant increase from their 2002 projection of 2.2 percent growth.Productivity ; Information technology

Projecting productivity growth: lessons from the U.S. growth resurgence

Following the 1995-2000 period of more rapid output growth and lower inflation in the United States, economists have strenuously debated whether improvements in economic performance can be sustained. The recession that began in March 2001 intensified the debate, and the economic impacts of the events of September 11 have yet to be fully understood. Both factors add to the considerable uncertainties about future growth that currently face decision makers in both the public and private sectors. ; In this article, the authors analyze the sources of U.S. labor productivity growth in the post-1995 period and present projections for both output and labor productivity growth for the next decade. Despite the 2001 downward revisions to U.S. gross domestic product and software investment, the authors show that information technology (IT) played a substantial role in the U.S. productivity revival. The article then outlines a methodology for projecting trend output and productivity growth. The base-case projection puts the rate of trend productivity growth at 2.21 percent per year over the next decade with a range of 1.33 to 2.92 percent, reflecting fundamental uncertainties about the rate of technological progress in IT-production and investment patterns. The central projection is only slightly below the average growth rate of 2.36 percent during the 1995-2000 period.Productivity ; Technology ; Economic development

A microscopic model for solidification

We present a novel picture of a non isothermal solidification process starting from a molecular level, where the microscopic origin of the basic mechanisms and of the instabilities characterizing the approach to equilibrium is rendered more apparent than in existing approaches based on coarse grained free energy functionals \`a la Landau. The system is composed by a lattice of Potts spins, which change their state according to the stochastic dynamics proposed some time ago by Creutz. Such a method is extended to include the presence of latent heat and thermal conduction. Not only the model agrees with previous continuum treatments, but it allows to introduce in a consistent fashion the microscopic stochastic fluctuations. These play an important role in nucleating the growing solid phase in the melt. The approach is also very satisfactory from the quantitative point of view since the relevant growth regimes are fully characterized in terms of scaling exponents.Comment: 7 pages Latex +3 figures.p

U. S. labor supply and demand in the long run

In this paper we model U.S. labor supply and demand in considerable detail in order to capture the enormous heterogeneity of the labor force and its evolution over the next 25 years. We represent labor supplies for a large number of demographic groups as responses to prices of leisure and consumption goods and services. The price of leisure is an after-tax wage rate, while the final prices of goods and services reflect the supply prices of the industries that produce them. By including demographic characteristics among the determinants of household preferences, we incorporate the expected demographic transition into our long-run projections of the U.S. labor market.Labor supply ; Labor market

Ecological Footprint Model Using the Support Vector Machine Technique

The per capita ecological footprint (EF) is one of the most widely recognized measures of environmental sustainability. It aims to quantify the Earth's biological resources required to support human activity. In this paper, we summarize relevant previous literature, and present five factors that influence per capita EF. These factors are: National gross domestic product (GDP), urbanization (independent of economic development), distribution of income (measured by the Gini coefficient), export dependence (measured by the percentage of exports to total GDP), and service intensity (measured by the percentage of service to total GDP). A new ecological footprint model based on a support vector machine (SVM), which is a machine-learning method based on the structural risk minimization principle from statistical learning theory was conducted to calculate the per capita EF of 24 nations using data from 123 nations. The calculation accuracy was measured by average absolute error and average relative error. They were 0.004883 and 0.351078% respectively. Our results demonstrate that the EF model based on SVM has good calculation performance

Bounding sup-norms of cusp forms of large level

Let f be an $L^2$-normalized weight zero Hecke-Maass cusp form of square-free level N, character $\chi$ and Laplacian eigenvalue $\lambda\geq 1/4$. It is shown that $\| f \|_{\infty} \ll_{\lambda} N^{-1/37}$, from which the hybrid bound $\|f \|_{\infty} \ll \lambda^{1/4} (N\lambda)^{-\delta}$ (for some $\delta > 0$) is derived. The first bound holds also for $f = y^{k/2}F$ where F is a holomorphic cusp form of weight k with the implied constant now depending on k.Comment: version 3: substantially revised versio

The microscopic detection of animal proteins in feeds

In the framework of the European Union funded research project STRATFEED for detection and identification of animal proteins in feeds, the microscopic method was optimized at several key steps and better documented. A check list was developed for uniform reporting. Characters of bone fragments, hairs, muscles and gills are fully documented. A so-called muscle ratio has been developed for the identification of muscle fibers at the level of vertebrate classes (mammals, birds and fishes). Both the improved protocol and the entire range of characters which can be observed, are documented in a Decision Support System called ARIES (Animal Remains Identification and Evaluation System). A second internet-based system called STRATFEED-DSS exclusively assists in identification of animal particles in feeds. A new strategy with microscopy as screening technique and either DNA or protein identification as confirmation technique is proposed. The advantages of this combination are the extremely low level of false negatives, low detection limits and the heat-resistant nature of microscopic detection, together with the possibility of a very specific identification of particles by one of the other methods

On the possible induced charge on a graphitic nanocone at finite temperature

Electronic excitations in a graphitic monolayer (graphene) in the long-wavelength approximation are characterized by the linear dispersion law, representing a unique example of the really two-dimensional "ultrarelativistic" fermionic system which in the presence of topological defects possesses rather unusual properties. A disclination that rolls up a graphitic sheet into a nanocone is described by a pointlike pseudomagnetic vortex at the apex of the cone, and the flux of the vortex is related to the deficit angle of the conical surface. A general theory of planar relativistic fermionic systems in the singular vortex background is employed, and we derive the analytical expression for the charge which is induced at finite temperature on some graphitic nanocones.Comment: 8 pages, minor changes, journal version (based on a talk given on QFEXT07, Leipzig, 2007