Entry, Exit and Investment-Specific Technical Change, Second Version

Using European data, this paper finds that (1) industry entry and exit rates are positively related to industry rates of investment-specific technical change (ISTC); (2) the sensitivity of industry entry and exit rates to cross-country differences in entry costs depends on industry rates of ISTC. The paper constructs a general equilibrium model in which the rate of ISTC varies across industries and new investment-specific technologies can be introduced by entrants or by incumbents. In the calibrated model, equilibrium behavior is consistent with stylized facts (1) and (2), provided the cost of technology adoption is increasing in the rate of ISTC.Entry, exit, turnover, investment-specific technical change, entry costs, vintage capital, embodied technical change, lumpy investment

Does Employment Protection Inhibit Technical Diffusion?

I ask whether differences in labor market performance between the US and Europe can be attributed to an interaction between employment protection legislation (EPL) and an acceleration in the rate of capital-embodied technical change associated with the advent of information technologies. I find that EPL is associated with a slowing in the diffusion of new technologies. I also find that an acceleration in the rate of embodied technical change has a negligible effect on employment in an undistorted economy. In addition, in the presence of EPL, employment decreases in the long run after such a shockembodiment, vintage capital, dismissal costs, employment protection, information technology

Mapping Prices into Productivity in Multisector Growth Models

Two issues related to mapping a multi-sector model into a reduced-form value-added model are often neglected: the composition of intermediate goods, and the distinction between value added productivity and gross output productivity. We demonstrate their quantitative significance for the case of the well known model of Greenwood, Hercowitz and Krusell (1997), who find that about 60% of economic growth can be attributed to investment-specific technical change (ISTC). When we recalibrate their model to allow for even a small equipment share of intermediates, we find that ISTC accounts for almost the entirety of postwar US growth.Intermediate goods, investment-specific technical change, growth accounting, gross output, multisector growth models

An R&D-Based Model of Multi-Sector Growth

We develop a multi-sector general equilibrium model in which productivity growth is driven by the production of sector-specific knowledge. In the model, we find that long run differences in total factor productivity growth across sectors are independent of the parameters of the knowledge production function except for one, which we term the fertility of knowledge. Differences in R&D intensity are also independent of most other parameters. The fertility of knowledge in the capital sector is central to the growth properties of the model economy.Endogenous technical change, multisector growth, fertility of knowledge, total factor productivity, R&D intensity, investment-specific technical change

Accounting for Research and Productivity Growth Across Industries

What factors underlie industry differences in research intensity and productivity growth? We develop a multi-sector endogenous growth model allowing for industry specific parameters in the production functions for output and knowledge, and in consumer preferences. We find that industry differences in both productivity growth and R&D intensity mainly reflect differences in "technological opportunities", interpreted as parameters of knowledge production. These include the capital intensity of R&D, knowledge spillovers, and diminishing returns to R&D. Among these parameters, we find that the degree of diminishing returns to R&D is the dominant factor when the model is calibrated to account for crossindustry differences in the US.Multisector growth, total factor productivity, R&D intensity, technological opportunity

Stretch-induced quenching in flame-vortex interactions

The flame-vortex interaction problem is a natural configuration in which several issues relevant to turbulent combustion can be addressed: effect of strain-rate and curvature, effect of the Lewis number, effect of heat losses, effect of complex chemistry, and flame-generated turbulence. In such an approach, the interaction of an isolated vortex with a laminar premixed flame is viewed as a unit process of a turbulent premixed flame in which the reaction zone keeps a laminar like structure locally; this is precisely the case of the wrinkled flame or flamelet regime in turbulent combustion. The present work complements previous studies and involves the study of the interaction of a vortex pair and a laminar premixed flame in a planar two-dimensional geometry, together with numerical simulations. This geometry is quite unique since most studies have considered axisymmetric vortex rings. Such a geometry offers several advantages over previous studies

Recanalization of the Chronically Occluded Internal Carotid Artery: Review of the Literature.

Introduction: We reviewed the literature on interventions for patients with medically refractory chronically occluded internal carotid artery (COICA) to assess the risks and/or benefits after recanalization via an endovascular technique (ET) or hybrid surgery (HS, i.e., ET plus carotid endarterectomy). Methods: A systematic search of the electronic databases was performed. Patients with COICA were classified into 4 different categories according to Hasan et al classification. Results: Eighteen studies satisfied the inclusion criteria. Only 6 studies involved an HS procedure. We identified 389 patients with COICA who underwent ET or HS; 91% were males. The overall perioperative complication rate was 10.1% (95% confidence interval [CI]: 7.4%-13.1%). For types A and B, the successful recanalization rate was 95.4% (95% CI: 86.5%-100%), with a 13.7% (95% CI: 2.3%-27.4%) complication rate. For type C, the success rate for ET was 45.7% (95% CI: 17.8%-70.7%), with a complication rate of 46.0% (95% CI: 20.0%-71.4%) for ET and for the HS technique 87.6% (95% CI: 80.9%-94.4%), with a complication rate of 14.0% (95% CI: 7.0%-21.8%). For type D, the success rate of recanalization was 29.8% (95% CI: 7.8%-52.8%), with a 29.8% (95% CI: 6.1%-56.3%) complication rate. Successful recanalization resulted in a symmetrical perfusion between both cerebral hemispheres, resolution of penumbra, normalization of the mean transit time, and improvement in Montreal Cognitive Assessment (MoCA) score (ΔMoCA = 9.80 points; P = 0.004). Conclusions: Type A and B occlusions benefit from ET, especially in the presence of a large penumbra. Type C occlusions can benefit from HS. Unfortunately, we did not identify an intervention to help patients with type D occlusions. A phase 2b randomized controlled trial is needed to confirm these findings

Development of organic fertilizers from food market waste and urban gardening by composting in Ecuador

Currently, the management of urban waste streams in developing countries is not optimized yet, and in many cases these wastes are disposed untreated in open dumps. This fact causes serious environmental and health problems due to the presence of contaminants and pathogens. Frequently, the use of specific low-cost strategies reduces the total amount of wastes. These strategies are mainly associated to the identification, separate collection and composting of specific organic waste streams, such as vegetable and fruit refuses from food markets and urban gardening activities. Concretely, in the Chimborazo Region (Ecuador), more than 80% of municipal solid waste is dumped into environment due to the lack of an efficient waste management strategy. Therefore, the aim of this study was to develop a demonstration project at field scale in this region to evaluate the feasibility of implanting the composting technology not only for the management of the organic waste fluxes from food market and gardening activities to be scaled-up in other developing regions, but also to obtain an end-product with a commercial value as organic fertilizer. Three co-composting mixtures were prepared using market wastes mixed with pruning of trees and ornamental palms as bulking agents. Two piles were created using different proportions of market waste and prunings of trees and ornamental palms: pile 1 (50:33:17) with a C/N ratio 25; pile 2: (60:30:10) with C/N ratio 24 and pile 3 (75:0:25) with C/N ratio 33), prepared with market waste and prunings of ornamental palm. Throughout the process, the temperature of the mixtures was monitored and organic matter evolution was determined using thermogravimetric and chemical techniques. Additionally, physico-chemical, chemical and agronomic parameters were determined to evaluate compost quality. The results obtained indicated that all the piles showed a suitable development of the composting process, with a significant organic matter decomposition, reached in a shorter period of time in pile 3. At the end of the process, all the composts showed absence of phytotoxicity and suitable agronomic properties for their use as organic fertilizers. This reflects the viability of the proposed alternative to be scaled-up in developing areas, not only to manage and recycle urban waste fluxes, but also to obtain organic fertilizers, including added value in economic terms related to nutrient contents.Peer ReviewedPostprint (published version

Entry, Exit and Investment-Specific Technical Change

Across industries, this paper finds that the rate of investment-specific technical change (ISTC) is positively related to rates of entry and exit. This finding is consistent with industry dynamics along the balanced growth path of a general equilibrium, multi-industry model of the plant lifecycle, in which technology adoption is costly and the rate of ISTC varies across industries. Results are robust to allowing for structural change induced by technological progress. The model also generates lumpy investment as a result of technology adoption by incumbents.Entry, exit, turnover, investment-specific technical change, entry costs, vintage capital, embodied technical change, selection, obsolescence, structural change, lumpy investment.