EFFECTS OF COMPACTION DUE TO MACHINERY TRAFFIC ON SOIL PORE CONFIGURATION

Soil compaction has been recognized as a severe problem in mechanized agriculture and has an influence on many soil properties and processes. Yet, there are few studies on the long-term effects of soil compaction, and the development of soil compaction has been shown through a limited number of soil parameters. The objectives of this study were to evaluate the persistence of soil compaction effects (three traffic treatments: T0, without traffic; T3, three tractor passes; and T5, five tractor passes) on pore system configuration, through static and dynamic determinations; and to determine changes in soil pore orientation due to soil compaction through measurement of hydraulic conductivity of saturated soil in samples taken vertically and horizontally. Traffic led to persistent changes in all the dynamic indicators studied (saturated hydraulic conductivity, K0; effective macro- and mesoporosity, εma and εme), with significantly lower values of K0, εma, and εme in the T5 treatment. The static indicators of bulk density (BD), derived total porosity (TP), and total macroporosity (θma) did not vary significantly among the treatments. This means that machine traffic did not produce persistent changes on these variables after two years. However, the orientation of the soil pore system was modified by traffic. Even in T0, there were greater changes in K0 measured in the samples taken vertically than horizontally, which was more related to the presence of vertical biopores, and to isotropy of K0 in the treatments with machine traffic. Overall, the results showed that dynamic indicators are more sensitive to the effects of compaction and that, in the future, static indicators should not be used as compaction indicators without being complemented by dynamic indicators.

Iowa Animal Industry News, 2011, Vol. 12, no. 1

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News.

Agglomeration and labour productivity in Spanish industry: a long-term analysis

This paper analyzes the relationship between spatial density of economic activity and interregional differences in the productivity of industrial labour in Spain during the period 1860-1999. In the spirit of Ciccone and Hall (1996) and Ciccone (2002), we analyze the evolution of this relationship over the long term in Spain. Using data on the period 1860-1999 we show the existence of an agglomeration effect linking the density of economic activity with labour productivity in the industry. This effect was present since the beginning of the industrialization process in the middle of the 19th century but has been decreasing over time. The estimated elasticity of labour productivity with respect to employment density was close to 8% in the subperiod 1860-1900, reduces to a value of around 7% in the subperiod 1914-1930, to 4% in the subperiod 1965-1979 and becomes insignificant in the final subperiod 1985-1999. At the end of the period analyzed there is no evidence of the existence of net agglomeration effects in the industry. This result could be explained by an important increase in the congestion effects in large industrial metropolitan areas that would have compensated the centripetal or agglomeration forces at work. Furthermore, this result is also consistent with the evidence of a dispersion of industrial activity in Spain during the last decades.

The geographical concentration of industry across Spanish Regions, 1856-1995

New economic geography models show that there may be a strong relationship between economic integration and the geographical concentration of industries. Nevertheless, this relationship is neither unique nor stable, and may follow a ?-shaped pattern in the long term. The aim of the present paper is to analyze the evolution of the geographical concentration of manufacturing across Spanish regions during the period 1856-1995. We construct several geographical concentration indices for different points in time over these 140 years. The analysis is carried out at two levels of aggregation, in regions corresponding to the NUTS-II and NUTS-III classifications. We confirm that the process of economic integration stimulated the geographical concentration of industrial activity. Nevertheless, the localization coefficients only started to fall after the beginning of the integration of the Spanish Economy into the international markets in the mid-70s, and this new path was not interrupted by Spain¿s entry in the European Union some years later

Insights into the molecular machinery of piecemeal microautophagy of the nucleus in "Saccharomyces cerevisiae"

Résumé : La microautophagie du noyau est un processus découvert chez la levure S. cerevisiae qui vise la dégradation de portions nucléaires dans la lumière vacuolaire. Ce processus appelé PMN (de l'anglais Piecemeal Microautophagy of the Nucleus) est induit dans des conditions de stress cellulaire comme la privation de nutriments, mais également par l'utilisation d'une drogue : la rapamycine. La PMN est due à l'interaction directe d'une protéine de la membrane externe de l'enveloppe nucléaire Nvj1p, et d'une protéine de la membrane vacuolaire Vac8p. L'interaction de ces deux protéines forme la jonction noyau-vacuole. Cette jonction guide la formation d'une invagination, qui englobe et étire vers la lumière vacuolaire une partie du noyau sous la forme d'un sac. Il s'en suit la libération d'une vésicule dégradée par les hydrolases. Les mécanismes moléculaires intervenant à différentes étapes de ce processus sont inconnus. Le but de ma thèse est de mettre en évidence de nouveaux acteurs qui interviennent dans la PMN. Dans la première partie de cette étude, nous présentons une procédure de sélection à la recherche de candidats jouant un rôle dans la PMN. Cette sélection a été effectuée dans la collection de mutants commercialisée chez Euroscarf. La procédure reposait sur l'observation que le nucléole (représenté par Nop1p) est le substrat préférentiel de la PMN dans des expériences de microscopie faites après induction de la PMN avec la rapamycine. Nous avons ainsi transformé la collection de mutants avec un plasmide portant le marqueur du nucléole Noplp. Par la suite, nous avons cherché par microscopie les mutants incapables de transférer Nop1p du noyau à la vacuole. Nous avons trouvé 318 gènes présentant un défaut de transfert de Nop1p par PMN. Ces gènes ont été classés par grandes familles fonctionnelles et aussi par leur degré de défaut de PMN. Egalement dans cette partie de l'étude, nous avons décrit des mutants impliqués dans le processus, à des étapes différentes. Dans la seconde partie de l'étude, nous avons regardé l'implication et le rôle de la V-ATPase, (une pompe à protons de la membrane vacuolaire}, sélectionnée parmi les candidats, dans le processus de PMN. Les inhibiteurs de ce complexe, comme la concanamycineA, bloquent l'activité PMN et semblent affecter le processus à deux étapes différentes. D'un autre côté, les jonctions «noyau-vacuole »forment une barrière de diffusion au niveau de la membrane vacuolaire, de laquelle Vphlp, une protéine de la V-ATPase, est exclue.

Iowa Animal Industry News, 2012, Vol. 14, no. 1

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa.Previously titled Animal Industry News.

Iowa Animal Industry News, January 7, 2011, Vol. 11, no. 1

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News.

Iowa Animal Industry News, January 20, 2011, Vol. 11, no. 2

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News.

Iowa Animal Industry News, March 4, 2011, Vol. 11, no. 4

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News.

Iowa Animal Industry News, February 4, 2011, Vol. 11, no. 3

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News. Previously titled Animal Industry News.

The geographical concentration of industry across Spanish Regions, 1856-1995

New economic geography models show that there may be a strong relationship between economic integration and the geographical concentration of industries. Nevertheless, this relationship is neither unique nor stable, and may follow a ?-shaped pattern in the long term. The aim of the present paper is to analyze the evolution of the geographical concentration of manufacturing across Spanish regions during the period 1856-1995. We construct several geographical concentration indices for different points in time over these 140 years. The analysis is carried out at two levels of aggregation, in regions corresponding to the NUTS-II and NUTS-III classifications. We confirm that the process of economic integration stimulated the geographical concentration of industrial activity. Nevertheless, the localization coefficients only started to fall after the beginning of the integration of the Spanish Economy into the international markets in the mid-70s, and this new path was not interrupted by Spain¿s entry in the European Union some years later

Agglomeration and labour productivity in Spanish industry: a long-term analysis

This paper analyzes the relationship between spatial density of economic activity and interregional differences in the productivity of industrial labour in Spain during the period 1860-1999. In the spirit of Ciccone and Hall (1996) and Ciccone (2002), we analyze the evolution of this relationship over the long term in Spain. Using data on the period 1860-1999 we show the existence of an agglomeration effect linking the density of economic activity with labour productivity in the industry. This effect was present since the beginning of the industrialization process in the middle of the 19th century but has been decreasing over time. The estimated elasticity of labour productivity with respect to employment density was close to 8% in the subperiod 1860-1900, reduces to a value of around 7% in the subperiod 1914-1930, to 4% in the subperiod 1965-1979 and becomes insignificant in the final subperiod 1985-1999. At the end of the period analyzed there is no evidence of the existence of net agglomeration effects in the industry. This result could be explained by an important increase in the congestion effects in large industrial metropolitan areas that would have compensated the centripetal or agglomeration forces at work. Furthermore, this result is also consistent with the evidence of a dispersion of industrial activity in Spain during the last decades.

On the industry experience premium and labor mobility

[cat] Hi ha evidència que l'experiència es remunera diferentment segons la indústria. Proposem un model teòric que explica aquestes diferències. Suposem que la mobilitat de treballadors aporta coneixement extern a l'empresa i això augmenta la seva productivitat. Els resultats mostren que l'experiència és millor remunerada en les indústries amb costos de mobilitat baixos, amb molt aprenentatge (learning-by-doing) i alt nivell tecnològic. A més, trobem una relació en forma de U entre la remuneració de l'experiència i el nivell d'absorció de coneixement extern, la substitutibilitat entre diferents tipus de treballadors i la varietat de coneixement dins la indústria. Els resultats són consistents amb l'evidència que les indústries intensives en I and D remuneren millor l'experiència.

Iowa Animal Industry News, 2013, Vol. 14, no. 1

Newsletter produced by Department of Agriculture and Land Stewardship about the animal industry in Iowa. Previously titled Animal Industry News.

Use of nanoparticles in Swiss industry: a targeted survey

A large number of applications using manufactured nanoparticles of less than 100 nm are currently being introduced into industrial processes. There is an urgent need to evaluate the risks of these novel particles to ensure their safe production, handling, use, and disposal. However, today we lack even rudimentary knowledge about type and quantity of industrially used manufactured nanoparticles and the level of exposure in Swiss industry. The goal of this study was to evaluate the use of nanoparticles, the currently implemented safety measures, and the number of potentially exposed workers in all types of industry. To evaluate this, a targeted telephone survey was conducted among health and safety representatives from 197 Swiss companies. The survey showed that nanoparticles are already used in many industrial sectors; not only in companies in the new field of nanotechnology, but also in more traditional sectors, such as paints. Forty-three companies declared to use or produce nanoparticles, and 11 imported and traded with prepackaged goods that contain nanoparticles. The following nanoparticles were found to be used in considerable quantities (> 1000 kg/year per company): Ag, Al-Ox, Fe-Ox, SiO2, TiO2, and ZnO. The median reported quantity of handled nanoparticles was 100 kg/year. The production of cosmetics, food, paints, powders, and the treatment of surfaces used the largest quantities of these nanoparticles. Generally, the safety measures were found to be higher in powder-based than in liquid-based applications. However, the respondents had many open questions about best practices, which points to the need for rapid development of guidelines and protection strategies