District economic overview and State economic conditions

Economic indicators ; Federal Reserve District, 5th

District/State economic conditions: District economic overview; State economic conditions

Economic indicators ; Federal Reserve District, 5th

A Theory of Factor Allocation and Plant Size

In this paper we develop a theory of how factors interact at the plant level. The theory has implications for: (1) the micro foundations for capital skill complementarity (2) the relationship between factor allocation and plant size and (3) the effects of trade and growth on the skill premium. The theory is consistent with certain facts about factor allocation and factor price changes in the 19th and 20th centuries.

A theory of factor allocation and plant size

In this paper we develop a theory of how factors interact at the plant level. The theory has implications for (1) the micro foundations for capital-skill complementarity, (2) the relationship between factor allocation and plant size, and (3) the effects of trade and growth on the skill premium. The theory is consistent with certain facts about factor allocation and factor price changes in the 19th and 20th centuries.Human capital ; Labor supply

Tim Hugh Interview

Bio: Tim Hugh loves what he does. For the past 12 years he has been the Executive Director for Asian American Showcase hosted by the Foundation for Asian American Independent Media (FAAIM). As a director Tim has kept the founding goals alive and at the center of everything the showcase is about. He finds happiness in helping others achieve their life time goals and in enriching and educating audiences. Tim treats the Foundation much like Herb Tam treated the Asian American artist collective Godzookie in the late 1990’s; with respect and altruism in the groups actions. Tim has steered the foundation in the right direction for the past dozen years and plans on continuing working for FAAIM as long as he finds happiness in helping others. - Bio written by Matt Holmes Visit the FAAIM website for additional information: http://www.faaim.org

Powder packing optimisation for clinker reduction in concrete

Globally, concrete is the most used construction material. Its embodied energy is relatively low, yet due to the vast quantities that are produced annually, it has substantial greenhouse gas (GHG) emissions associated with it. Of the concrete constituents, the manufacture of clinker - the basis of all conventional cements - contributes the most significant emissions. Therefore, to reduce the emissions associated with concrete manufacture, there has been extensive research into how clinker content can be reduced without compromising desired concrete properties. Existing methods for clinker reduction have, however, only allowed clinker replacement to a limited extent. This research investigated the more efficient use of clinker to minimise clinker content required to achieve desired mechanical and durability properties of concrete. The optimisation of powder (materials < 125 µm) packing, using filler materials with varying fineness, was identified to potentially increase clinker efficiency. The optimisation undertaken was the maximisation of powder packing density but without adversely affecting workability. The investigation entailed the application of analytical particle packing density models as well as experimental investigation. Two particle packing models, the Compaction Interaction Packing Model (CIPM) and the Modified Andreasen and Andersen Curve (MAAC) were applied. Various methods for determining the packing density of powder combinations were investigated which informed the use of the mixing energy test to provide experimental packing density data for the modelling procedures. The CIPM was used to optimise the powder phases of concrete as it incorporated the effect of surface forces on powder packing and the MAAC was used to complete the optimisation of fine and coarse aggregate materials. It was necessary to calibrate the CIPM through the selection of various model constants, based on the minimisation of the average error associated with predicted packing density. Despite the incorporation of surface force effects, the CIPM did not predict the trend in packing density observed for various experimental powder combinations with consistent accuracy. Combinations of cement with limestone of high and low fineness (relative to cement) were most accurately predicted but combinations with limestones of similar fineness to cement were less accurate. It was therefore apparent that the model inadequately accounted for the effects of varying particle size and the corresponding influence of surface forces on these particles. However, for practicality, model constants which minimised overall error were used to determine powder combinations enabling maximum packing density for use in optimised concrete mix design. Concrete mixes were designed in 2 phases. Initially water content was fixed, and limestone content was successively increased to 40 vol. % (Phase 1). Despite the formation of mixtures according to maximum packing density, the results showed that optimisation of packing density with a fixed water content was insufficient to reduce clinker content without adversely affecting compressive strength. However, workability was maintained without excessive superplasticiser (SP) dosage and oxygen permeability, water sorptivity and accelerated drying shrinkage were either improved or not adversely affected. This was attributed to the ability of fine fillers to prevent interconnectivity of the pore structure and the decreased volume of gel hydration products leading to reduced drying shrinkage. Compressive strength was tested for a binary (cement/limestone) and ternary (cement /limestone/fly ash (FA)) binder blend for Phase 2 in conjunction with a substantially reduced water content. Workability was adversely affected and both mixes required high SP doses, however, the FA blend required a relatively lower dose. Compressive strength was again decreased relative to the reference mix but when comparing Phase 1 and 2 mixes with predicted strength for equivalent w/c ratios, compressive strength was relatively unchanged, inferring little benefit of packing optimisation. However, binder efficiency indices (‘bi’) (between 5.3 and 6.9 kg/m3 /MPa) were reduced relative to data from previous investigations with similar strength class (between 10 to 20 kg/m3 /MPa), inferring increased binder performance. Powder packing optimisation thereby has the potential to enable clinker reduction, particularly for lower strength grade concrete, without adversely affecting compressive strength. Furthermore, the relatively unaffected durability indicators portray the beneficial effects of powder packing optimisation on increasing the impenetrability of concrete microstructure and it potential use in applications where durability is of importance. These findings also pointed to further possible reductions in the binder efficiency index below 5 kg/m3 /MPa if water content is further reduced (to maintain low water: cement ratio) and reactive SCMs are incorporated. However, further investigation and understanding of the fundamentals of powder packing is necessary to achieve a fully predictive process of low-clinker concrete mix design that can be universally applicable

A plague of weasels and ticks: animal introduction, ecological disaster, and the balance of nature in Jamaica, 1870-1900

Towards the end of the nineteenth century, British colonists in Jamaica became increasingly exasperated by the damage caused to their sugar plantations by rats. In 1872, a British planter attempted to solve this problem by introducing the small Indian mongoose (Urva auropunctata). The animals, however, turned on Jamaica’s insectivorous birds and reptiles, leading to an explosion in the tick population. This paper situates the mongoose catastrophe as a closing chapter in the history of the nineteenth-century acclimatization movement. While foreign observers saw the introduction of the mongoose as a cautionary tale, caricaturing British Jamaica as overrun by a plague of weasels and ticks, British colonists, administrators and naturalists – identifying a gradual decline of both populations – argued that the ‘balance of nature’ would eventually reassert itself. As this paper argues, through this dubious claim they were attempting to retrospectively rationalize or justify the introductions and their disastrous aftermath. This strategy enabled them to gloss over the lasting ecological damage caused by the mongoose, and allowed its adherents to continue their uncritical support of both the Jamaican plantation economy and animal introductions in the British Empire.publishedVersio

Effect of Forage Stand Termination Method and Fertilization History on Greenhouse Gas Emissions, Nutrient Supply Rates, and Soil Carbon Dynamics

While the majority of land used for growing forages in Saskatchewan is not fertilized on an annual basis, nitrogen (N) fertilization is often used to revitalize declining stands or for grass seed production. Once a stand is ready to be terminated, typically either a combination of tillage and herbicide or herbicide alone is used to kill the vegetation. Termination method is anticipated to have a significant effect on the rates and amounts of greenhouse gas (GHG) production, as well as affect carbon (C) and nutrient cycling in the soil. The objective of this thesis work was to examine the influence of grass forage stand termination method on GHG production, nutrient cycling, and dynamics of various soil C pools. Additionally, the influence of two previous years of N fertilizer addition versus no N fertilizer addition was examined. In a laboratory incubation of intact soil cores collected from two forage grass seed production fields in northeastern Saskatchewan (Arborfield brome grass in August 2013 and Carrot River timothy sites 1 and 2 in May 2014), termination by a combination of tillage and glyphosate caused a reduction of up to 16% in carbon dioxide (CO2) emissions compared to glyphosate alone. The tillage/glyphosate termination also tended to decrease nitrous oxide (N2O) emissions when compared to glyphosate alone. Prior N fertilization for two years resulted in increased emissions of both CO¬2 and N2O, as well as slightly lower phosphate (PO43-) supply rates in the surface soil. Nitrogen supply rates were generally increased by N past fertilization, especially the ammonium (NH4+) supply rate, which was as much as 18% higher than in unfertilized plots. The field experiment conducted on the two Carrot River sites (CR1 and CR2) from August, 2013 to October, 2014 examined changes in soil organic C (SOC) pools. Prior N fertilization increased the amount of light fraction, water extractable, and microbial biomass C (LFOC, WEOC, and MBC, respectively) compared to the unfertilized plots. Termination with tillage significantly increased the LFOC concentrations in the following year but this difference disappeared by the end of the 2014 season. Tillage also tended to reduce the concentrations of WEOC and MBC over the course of the study. There were no significant differences between treatments in any of the C pools at the end of the study. Therefore, the conclusion of this thesis work is that the current practice of grass forage stand termination through a combination of tillage and glyphosate is a beneficial management practice in the soils studied through reduced greenhouse gas emissions