Search results for " production function"

Prediction of Soil Formation as a Function of Age Using the Percolation Theory Approach

2018

Recent modeling and comparison with field results showed that soil formation by chemical weathering, either from bedrock or unconsolidated material, is limited largely by solute transport. Chemical weathering rates are proportional to solute velocities. Nonreactive solute transport described by non-Gaussian transport theory appears compatible with soil formation rates. This change in understanding opens new possibilities for predicting soil production and depth across orders of magnitude of time scales. Percolation theory for modeling the evolution of soil depth and production was applied to new and published data for alpine and Mediterranean soils. The first goal was to check whether the e…

Worldwide distribution of continental rock lithology: Implications for the atmospheric/soil CO2uptake by continental weathering and alkalinity river …

2003

[1] The silicate rock weathering followed by the formation of carbonate rocks in the ocean, transfers CO2 from the atmosphere to the lithosphere. This CO2 uptake plays a major role in the regulation of atmospheric CO2 concentrations at the geologic timescale and is mainly controlled by the chemical properties of rocks. This leads us to develop the first world lithological map with a grid resolution of 1° × 1°. This paper analyzes the spatial distribution of the six main rock types by latitude, continents, and ocean drainage basins and for 49 large river basins. Coupling our digital map with the GEM-CO2 model, we have also calculated the amount of atmospheric/soil CO2 consumed by rock weathe…

Labor productivity and firm-level TFP with technology-specific production functions

2020

Abstract We investigate the technological dimension of productivity, presenting an empirical methodology based on mixture models to disentangle the labor productivity differences associated with the firm's choice of technology (BTFP) and those related to the firm's ability to exploit the adopted technology (WTFP). The estimation endogenously determines the number of technologies (in the sector) and degree of technology sharing across firms (i.e., for each firm, the probability of using a given technology). By using comparable data for about 35,000 firms worldwide distributed across 22 (two-digit) sectors, we show BTFP to be at least as important as WTFP in explaining the labor productivity …

How does public spending affect technical efficiency? Some evidence from 15 European countries

2020

The relationship between government size and economic growth has been widely debated. Revisiting the subject from a distinct angle with respect to the mainstream approach, we provide an empirical analysis of the impact of government size on technical efficiency. The aim of this paper is to estimate the impact of public sector's size and of public expenditure components on 15 European countries’ technical efficiency from 1996 to 2014 by using a True Random Effect model. Using the total public expenditure as a proxy for the government size we estimate simultaneously national optimal production function and technical efficiency by controlling for income distribution and institutional quality. …

ESSAYS ON THE DRIVERS OF FIRM COMPETITIVENESS

2020

Determining Optimal Seasonal Irrigation Depth Based on Field Irrigation Uniformity and Economic Evaluations: Application for Onion Crop

2016

The crop water production function (WPF), representing the relationship between crop yield and seasonal irrigation water, is a useful tool for irrigation planning purposes. The objective of the paper is to propose a methodology to evaluate the optimal seasonal irrigation depth based on the crop production function, the field distribution uniformity, and economic considerations. An extended unpublished database experimentally obtained on the onion crop on the island of Kula, Hawaii, was initially used to assess the crop WPF. The combination between the crop WPF and the model representing the field distribution uniformity allowed determining the area subjected to underirrigation and overirrig…

A micro-founded approach to regional innovation in Italy

2022

Recent regional studies have taken a micro-founded perspective to uncover the influence of the external environment on the firm-level innovative performance. Despite the marked spatial disparities, there is a general lack of recent evidence on Italian regional innovation from a micro perspective. This paper fills this gap in the evidence base by estimating regional Knowledge Production Functions using Italian micro-data collected in the Community Innovation Survey. In particular, here we focus on the regional differences in the relationship between innovative inputs and outputs and on the ability of firms to absorb external knowledge. This analysis allows us to outline different regional in…

Chemical weathering of volcanic rocks at the island of Pantelleria, Italy: Information from soil profile and soil solution investigations

2007

Abstract Concentrations of major, minor and trace elements were determined in soil profiles and soil solutions from the island of Pantelleria, Sicily Channel, to evaluate the weathering extent of soils evolved on trachytic and pantelleritic rocks and the aqueous transport of elements by their soil solutions. The chemical index of alteration (CIA) indicates a low-to-moderate degree of weathering; consistently, the mineralogical and geochemical imprints of the parent rocks are generally preserved. The chemical weathering appears to be incongruent, owing to primary minerals and glass dissolving to a variable degree while secondary minerals have formed. Based on the calculated saturation state …

Over-estimation of efficiency of weathering in tropical “Red Soils”: its importance for geoecological problems

2000

Abstract Weathering and soil formation rates are regarded as the main criteria of a tolerable soil loss. The efficiency of weathering in the seasonal semiarid tropics has often been greatly over-estimated especially in the geomorphologic literature in which weathering is assumed to be as fast or even faster than surface erosion. Six selected “Red Soils” in two intramontane basins of hyperthermic SW Nepal near the border with India, with 1500–1750 mm annual rainfall (5 humid months), and a “Black Soil” near Baroda, Gujarat, India (3–4 humid months) were studied mineralogically. Two of the “Red Soils” have TL ages between 10 and 30 ka, the “Black Soil” has one of about 10 ka. The yellowish si…

Clay minerals, oxyhydroxide formation, element leaching and humus development in volcanic soils

2008

Aweathering sequence with soils developing on volcanic, trachy-basaltic parent materials with ages ranging from 100–115,000 years in the Etna region served as the basis to analyse and calculate the accumulation and stabilisation mechanisms of soil organic matter (SOM), the transformation of pedogenic Fe and Al, the formation and transformation of clay minerals, the weathering indices and, by means of mass-balance calculations, net losses of the main elements. Although the soils were influenced by ash depositions during their development and the soil on the oldest lava flow developed to a great extent under a different climate, leaching of elements and mineral formation and transformation co…