Probing gravity and the neutrinos with cosmology

This thesis is related to the growth of structure in the late-time Universe. It addresses both the measurement of this structure and the use of such information in constraining fundamental underlying physics. This includes the gravitational framework and the sum of the three neutrinos’mass. The thesis starts by using weak gravitational lensing data (CFHTLS) to constrain a modification of gravity that is invoked to provide the observed accelerated expansion in the Universe. This is shown to disfavour the model in question. It is, however, incapable of placing any bounds on the growth parameter that represents extensions to gravity. The future of weak lensing in probing general relativity is illustrated with forecasts on the growth signature and power spectrum parameter using the proposed Euclid probe. A measurement is made on the clustering of Luminous Red Galaxies (LRGs) in the Universe. This represents a new photometric galaxy clustering angular power spectrum: MegaZ LRG Data Release 7 (DR7). The cosmological constraints are demonstrated to be competitive with spectroscopic surveys and complementary to the WMAP5 data. Specifically, bounds of f_b \equiv \Omega _b / \Omega _m = 0.173 \pm 0.046 and \Omega_m = 0.260 \pm 0.035 are placed. Potential systematics in the data are discussed and examined. The work concludes by placing one of the most stringent constraints available of the sum of the three neutrino masses. By combining cosmic microwave background information, distance measures from supernovae and baryon acoustic oscillations with growth from the MegaZ LRG galaxy clustering data, produced earlier, the limit is found to be \sum m_v < 0.281 eV at the 95% confidence level

Tillage and herbicide indices illustrate relationships among cropping systems

Non-Peer ReviewedFarming systems based on reduced inputs and increased diversity of crop types are of interest to producers as alternatives to conventional systems. Indices can be derived to estimate the impact of various farming practices on the system and its environment. The paper presents methods for calculating simple, weighted and modeled herbicide and tillage indices. The simple indices are based solely on farm input use records. The simple indices illustrated in the paper are number of herbicide applications and number of tillage operations. The weighted indices incorporate some knowledge about the operations using external data sources. The examples illustrated are herbicide active ingredient and cumulative disturbance. The third level of complexity is to model the impact of the operations on the environment using several external sources. The paper calculates environmental exposure to herbicides and residue removed. All indices are calculated for nine cropping systems included in the Scott Alternative Cropping System Study. Each index ranked the cropping systems differently. Number of herbicide applications underestimated the relative amount of active ingredient applied in the high input systems as compared to the reduced input (minimum tillage) systems. The types of herbicide necessary to control weeds in high input systems tended to result in higher environmental exposure to herbicides. The number of tillage passes also underestimated the relative amount of disturbance in the high input systems as compared to the organic systems. The amount of residue removed in the organic and high input systems was similar

Alternative cropping systems alter residual weed community composition

Non-Peer ReviewedWeed community composition was assessed in 1994 through 2000 in the Alternative Cropping System Project at Scott, SK. Weeds were counted during July after in-crop management practices had been used. The weed community was composed of 67 species. The nine arable cropping systems in the project were compared in terms of weed frequency, density, and diversity. Changes in weed community composition over time are displayed as a principal response curve (PRC). This method compares the weed community in the cropping systems to a reference system. PRCs are based on redundancy analysis, a constrained form of principal components analysis. Weed densities are constrained to be linear combinations of the interaction of system and year. Seven years and initial spatial variation (4 replicates and 36 sub-plots) are removed as covariables. The PRC analysis identified problematic weed species associated with the cropping systems after six years. Green foxtail, lamb’s-quarters and stinkweed were abundant in the three organic input systems. Wild oats, shepherd’s-purse and narrow-leaved hawk’s-beard were abundant in the reduced input systems. The three organic systems appear to have reached equilibrium after a three-year transition period. The problematic weed species in the reduced systems still appear to be increasing after six years

The increase of Binding Energy and Enhanced Binding in Non-Relativistic QED

We consider a Pauli-Fierz Hamiltonian for a particle coupled to a photon field. We discuss the effects of the increase of the binding energy and enhanced binding through coupling to a photon field, and prove that both effects are the results of the existence of the ground state of the self-energy operator with total momentum $P = 0$.Comment: 14 pages, Latex. Final version, accepted for publication in J. Math. Phy

Crop productivity with alternative input use and cropping diversity strategies

Non-Peer Reviewe

Chondroid tenosynovial giant cell tumour : a rarity in the temporomandibular joint

Tenosynovial giant cell tumours of the temporomandibular joint (TMJ) are extremely rare, particularly the subset of chondroid tumours. They can be broadly divided into localised and diffuse types, of which we know of only 116 reported cases in the TMJ. Rarer still are the subset of chondroid tenosynovial giant cell tumours, of which we know of only 30 cases that have affected the TMJ. We present a case that involved the TMJ, and include a discussion of its management

The Scott alternative cropping systems study: background and treatment structure

Non-Peer ReviewedOver the past 20 years grain crop production on the Canadian prairies has experienced the adoption of minimum tillage practises and extended cropping rotations that incorporate an ever increasing diversity of crops. This change has been driven in part by long term rotation studies revealing soil erosion and degradation with mechanical tillage and numerous short term studies that document the benefits of diverse cropping systems. Change has been accelerated in recent years as producers faced with the challenge of depressed grain prices adopt technological change, respond to consumer demands, and reduce inputs in an attempt to remain profitable. These changes in farm management practices while having short term economic objectives also have long term implications for the environment, production sustainability, and food safety. While long term studies in the past have generally compared components of production systems such as rotations or soil amendments, a long term multidisciplinary cropping system study initiated at Scott in 1994 is based on a comparison of different cropping systems. To evaluate the sustainability of arable crop production on the Canadian Prairies the study incorporates three levels of inputs (Organic, Reduced, High) and three levels of cropping diversity (low, diverse annual grains, diverse annual forage) in a six year rotation cycle. This paper is the first in a series of papers discussing results from the first 6 year cycle. This document provides an introduction to the issue of sustainable agricultural crop production with a focus on the objectives, experimental design of the study, and management practices within each of the systems

Chemical, mineralogical and petrological characterization of Gyaza iron ore deposit, Katsina State, Nigeria

No Abstract