Update rules and interevent time distributions: Slow ordering vs. no ordering in the Voter Model

We introduce a general methodology of update rules accounting for arbitrary interevent time distributions in simulations of interacting agents. In particular we consider update rules that depend on the state of the agent, so that the update becomes part of the dynamical model. As an illustration we consider the voter model in fully-connected, random and scale free networks with an update probability inversely proportional to the persistence, that is, the time since the last event. We find that in the thermodynamic limit, at variance with standard updates, the system orders slowly. The approach to the absorbing state is characterized by a power law decay of the density of interfaces, observing that the mean time to reach the absorbing state might be not well defined.Comment: 5pages, 4 figure

Agricultural productivity in the United States: catching-up and the business cycle

This paper examines the relation between the business cycle and convergence in levels of total factor productivity (TFP) across states. First, we find evidence of convergence in TFP levels across the different phases of the business cycle, but the speed of convergence was much greater during periods of contraction in economic activity than during periods of expansion. Second, we find that technology embodied in capital was an important source of productivity growth in agriculture. As with the rate of catch-up, the embodiment effect was much stronger during low economic activity phases of the business cycle.Agriculture, Convergence, Total factor productivity

Capital as a Factor of Production in OECD Agriculture: Measurement and Data

This paper provides a farm sector comparison of levels of capital input for fourteen OECD countries for the period 1973-2002. The starting point for construction of a measure of capital input is the measurement of capital stock. Estimates of depreciable capital are derived by representing capital stock at each point of time as a weighted sum of past investments. The weights correspond to the relative efficiencies of capital goods of different ages, so that the weighted components of capital stock have the same efficiency. Estimates of the stock of land are derived from balance sheet data. We convert estimates of capital stock into estimates of capital service flows by means of capital rental prices. Comparisons of levels of capital input among countries require data on relative prices of capital input. We obtain relative price levels for capital input via relative investment goods prices, taking into account the flow of capital input per unit of capital stock in each country.Financial Economics,

Agricultural productivity in the United States: catching-up and the business cycle

This paper examines the relation between the business cycle and convergence in levels of total factor productivity (TFP) across states. First, we find evidence of convergence in TFP levels across the different phases of the business cycle, but the speed of convergence was much greater during periods of contraction in economic activity than during periods of expansion. Second, we find that technology embodied in capital was an important source of productivity growth in agriculture. As with the rate of catch-up, the embodiment effect was much stronger during low economic activity phases of the business cycle

Target and non-target screening strategies for organic contaminants, residues and illicit substances in food , environmental and human biological samples by UHPLC-QTOF-MS

In this paper, we illustrate the potential of ultra-high performance liquid chromatography (UHPLC) coupled with hybrid quadrupole time-of-flight mass spectrometry (QTOF MS) for large scale screening of organic contaminants in different types of samples. Thanks to the full-spectrum acquisition at satisfactory sensitivity, it is feasible to apply both (post)-target and non-target approaches for the rapid qualitative screening of organic pollutants in food, biological and environmental samples. Different strategies have been applied and compared in this work. The first approach consists of target screening based on automatically extracting the exact analyte masses with a narrow mass window (`10 mDa). The selection of analytes can be made after MS acquisition as non-specific analyte information is required when injecting the samples. The second, non-targeted approach, consists of a first component detection step followed by the search of the detected components in home-made spectral libraries. In this work, two types of libraries have been evaluated: a theoretical database, including the molecular formula of a large number of pollutants ($1000), and an empirical mass spectra library which includes a lower number of compounds for which reference standards were available. In all cases the confidence of the identification process was excellent, thanks to the value of information given in QTOF MSE acquisition mode (i.e. simultaneous acquisition of low and high energy TOF MS spectra in a unique run). Both, target and non-target approaches, are complementary and both have advantages and drawbacks. Their application to different types of samples has allowed the detection of diverse organic compounds, for example the mycotoxin fumonisin B1 in food samples, cocaine and several metabolites in human urine, as well as several pesticides, antibiotics and drugs of abuse in urban wastewate

Real Capital Input in OECD Agriculture: A Multinational Comparison

This paper provides a farm sector comparison of relative levels of capital input for seventeen OECD countries for the period 1973-2011. The starting point for construction of a measure of capital input is the measurement of capital stock. Estimates of depreciable capital are derived by representing capital stock at each point of time as a weighted sum of past investments. The weights correspond to the relative efficiencies of capital goods of different ages, so that the weighted components of capital stock have the same efficiency. The capital stocks of land are measured as implicit quantities derived from balance sheet data. We convert estimates of capital stock into estimates of capital service flows by means of capital rental prices. Implicit rental prices for each asset are based on the correspondence between the purchase price of the asset and the discounted value of future service flows derived from that asset. Finally, comparisons of levels of capital input among countries require data on relative prices of capital input. We obtain relative price levels for capital input via relative investment goods prices, taking into account the flow of capital input per unit of capital stock in each country

Productivity and international competitiveness of agriculture in the European Union and the United States

This study looks at international competitiveness of agriculture in the European Union and the United States. The most intuitive concept is that of price competitiveness.We calculate relative prices for 11 member states of the European Union and the United States for the period 1973–2002. We assume that markets are perfectly competitive and in long-run equilibrium, so that the observed price always equals average total cost, as measured by the cost dual to the production function. This assumption is used in our calculation of relative competitiveness and productivity gaps between the European Union and the United States and in our decomposition of relative price movements between changes in relative input prices and changes in relative productivity levelsPublicad

Design of Science Orbits About Planetary Satellites: Application to Europa

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76381/1/AIAA-19464-587.pd

Biological Degradation and Biostability of Nanocomposites Based on Polysulfone with Different Concentrations of Reduced Graphene Oxide

Increasing incorporation of rGO in the polysulfone polymer generates materials with improved chemical and mechanical stability and less prone to biodegradation at the end of the nanocomposite life cycle. The results of attenuated total reflection infrared (ATR?IR) and mechanical strength, after exposure to wastewater influent, show that the increasing concentrations of rGO into the polymer matrix reduce changes in the nanocomposite properties. The increasing incorporation of rGO also increases growth inhibition of the wastewater microbial population on the surface of nanocomposites. Highest biofilm inhibition and material stability are observed with nanocomposites containing 3 wt% rGO. These results suggest that reduction in the material biodegradation is linked to the inhibition of biofilm growth on the nanocomposite surface due to the antimicrobial properties of rGO. This study demonstrates, for the first time, that the amount of rGO incorporated in the nanocomposite impact the biodegradability and end of life of polysulfone nanocomposites

Novel effects of strains in graphene and other two dimensional materials

The analysis of the electronic properties of strained or lattice deformed graphene combines ideas from classical condensed matter physics, soft matter, and geometrical aspects of quantum field theory (QFT) in curved spaces. Recent theoretical and experimental work shows the influence of strains in many properties of graphene not considered before, such as electronic transport, spin-orbit coupling, the formation of Moir\'e patterns, optics, ... There is also significant evidence of anharmonic effects, which can modify the structural properties of graphene. These phenomena are not restricted to graphene, and they are being intensively studied in other two dimensional materials, such as the metallic dichalcogenides. We review here recent developments related to the role of strains in the structural and electronic properties of graphene and other two dimensional compounds.Comment: 75 pages, 15 figures, review articl