Carbon content in Amazonian Oxisols after forest conversion to pasture

Soil plays an important role in the C cycle, and substitution of tropical forest by cultivated land affects C dynamic and stock. This study was developed in an area of expansion of human settlement in the Eastern Amazon, in Itupiranga, State of Pará, to evaluate the effects of native forest conversion to Brachiaria brizantha pasture on C contents of a dystrophic Oxisol. Soil samples were collected in areas of native forest (NF), of 8 to 10 year old secondary forest (SF), 1 to 2 year old SF (P1-2), 5 to 7 year old SF (P5-7), and of 10 to 12 year old SF (P10-12), and from under pastures, in the layers 0-2, 2-5 and 5-10 cm, to evaluate C levels and stocks and carry out separation of OM based on particle size. After deforestation, soil density increased to a depth of 5 cm, with greater increase in older pastures. Variation in C levels was greatest in the top soil layer; C contents increased with increasing pasture age. In the layers 2-5 and 5-10 cm, C content proved to be stable for the types of plant cover evaluated. Highest C concentrations were found in the silt fraction; however, C contents were highest in the clay fraction, independent of the plant cover. An increase in C associated with the sand fraction in the form of little decomposed organic residues was observed in pastures, confirming greater sensitivity of this fraction to change in soil use.

The European sugar regime new legislation and wto rules

[cat] El 20 de febrer de 2006 es va aprovar el Reglament núm. 318/2006 del Consell que reforma l'Organització Comuna de Mercats del sucre. L'article analitza els canvis introduïts en el nou règim europeu del sucre i valora la seva adequació a les normes i demandes internacionals de liberalització del comerç agrícola. Es conclou que la reforma ha estat el mínim necessari per fer front als reptes internacionals: la recent resolució de l'Òrgan de Solució de Diferències de l'Organització Mundial del Comerç i les demandes de liberalització plantejades en el marc de la Ronda de Doha.

Deciding the sale of a life policy in the viatical market: Implications on individual welfare

[cat] En aquest article, es presenta un model econòmic que permet determinar la venda o no d'una pòlissa de vida (total o en part) per part d'un assegurat malalt terminal en el mercat dels viatical settlements. Aquest mercat va aparèixer a finals de la dècada dels 80 a conseqüència de l'epidèmia de la SIDA. Actualment, representa una part del mercat dels life settlements. Les pòlisses que es comercialitzen en el mercat dels viaticals són aquelles on l'assegurat és malalt terminal amb una esperança de vida de dos anys o menys. El model és discret i considera només dos períodes (anys), ja que aquesta és la vida residual màxima que contempla el mercat. L'agent posseix una riquesa inicial que ha de repartir entre consum i herència. S'introdueix en primer lloc la funció d'utilitat esperada del decisor i, utilitzant programació dinàmica, es dedueix l'estratègia que reporta una utilitat més gran (no vendre/vendre (en part) la pòlissa en el moment zero/vendre (en part) la pòlissa en el moment ú). L'òptim depèn del preu de la pòlissa venuda i de paràmetres personals de l'individu. Es troba una expressió analítica per l'estratègia òptima i es realitza un anàlisi de sensibilitat.

Trade policy and regional inequalities

This paper aims to analyse the effects of trade policies in the pattern of regional inequalities within a country. Inspired firstly, by the debate concerning the role of protectionist policies in the settlement of a pattern of striking regional inequalities in the Spanish industrialisation process and secondly, by current evidence of an increase in these inequalities following the entry of Spain in the EU (1986), we set a model that shows that trade liberalisation increases regional inequalities.

The Spirit Lake Massacre,1918.

This is the story of the Spirit Lake Massacre of 1857, written by Thomas Teakle. The massacre came as the culminating episode of incidents intimately connected with the settlement of northern and western Iowa.

Geosynthetic Reinforced Soil for Low-Volume Bridge Abutments, January 2012

This report presents a review of literature on geosynthetic reinforced soil (GRS) bridge abutments, and test results and analysis from two field demonstration projects (Bridge 1 and Bridge 2) conducted in Buchanan County, Iowa, to evaluate the feasibility and cost effectiveness of the use of GRS bridge abutments on low-volume roads (LVRs). The two projects included GRS abutment substructures and railroad flat car (RRFC) bridge superstructures. The construction costs varied from $43k to $49k, which was about 50 to 60% lower than the expected costs for building a conventional bridge. Settlement monitoring at both bridges indicated maximum settlements ≤1 in. and differential settlements ≤ 0.2 in transversely at each abutment, during the monitoring phase. Laboratory testing on GRS fill material, field testing, and in ground instrumentation, abutment settlement monitoring, and bridge live load (LL) testing were conducted on Bridge 2. Laboratory test results indicated that shear strength parameters and permanent deformation behavior of granular fill material improved when reinforced with geosynthetic, due to lateral restraint effect at the soilgeosynthetic interface. Bridge LL testing under static loads indicated maximum deflections close to 0.9 in and non-uniform deflections transversely across the bridge due to poor load transfer between RRFCs. The ratio of horizontal to vertical stresses in the GRS fill was low (< 0.25), indicating low lateral stress on the soil surrounding GRS fill material. Bearing capacity analysis at Bridge 2 indicated lower than recommended factor of safety (FS) values due to low ultimate reinforcement strength of the geosynthetic material used in this study and a relatively weak underlying foundation layer. Global stability analysis of the GRS abutment structure revealed a lower FS than recommended against sliding failure along the interface of the GRS fill material and the underlying weak foundation layer. Design and construction recommendations to help improve the stability and performance of the GRS abutment structures on future projects, and recommendations for future research are provided in this report.

Integral Bridge Abutment-to-Approach Slab Connection Final Report, June 2008

The Iowa Department of Transportation has long recognized that approach slab pavements of integral abutment bridges are prone to settlement and cracking, which manifests as the “bump at the end of the bridge”. A commonly recommended solution is to integrally attach the approach slab to the bridge abutment. Two different approach slabs, one being precast concrete and the other being cast-inplace concrete, were integrally connected to side-by-side bridges and investigated. The primary objective of this investigation was to evaluate the approach slab performance and the impacts the approach slabs have on the bridge. To satisfy the research needs, the project scope involved a literature review, survey of Midwest Department of Transportation current practices, implementing a health monitoring system on the bridge and approach slab, interpreting the data obtained during the evaluation, and conducting periodic visual inspections. Based on the information obtained from the testing the following general conclusions were made: The integral connection between the approach slabs and the bridges appear to function well with no observed distress at this location and no relative longitudinal movement measured between the two components; Tying the approach slab to the bridge appears to impact the bridge; The two different approach slabs, the longer precast slab and the shorter cast-in-place slab, appear to impact the bridge differently; The measured strains in the approach slabs indicate a force exists at the expansion joint and should be taken into consideration when designing both the approach slab and the bridge; The observed responses generally followed an annual cyclic and/or short term cyclic pattern over time.