2002 soil and weed survey conducted on Saskatchewan organic cropland

Non-Peer ReviewedA soil survey and a weed survey were conducted on 5% of the organic farms in Saskatchewan, in the four major agricultural eco-regions in the 2002. Soil tests were taken in April and May prior to planting. Phosphorus levels were deficient in all regions. Nitrogen and sulphur varied between fields but were lowest over all in the boreal transition eco-region. Potassium was high in all regions. The weed surveys were conducted in July on the same fields as the soil survey. The most abundant species was green foxtail (Setaria virids (L.) Beauv.), wild oats was the fourth most abundant and the seventh most abundant species was Canada thistle (Cirsium arvense (L.) Scop.). Annual broad-leaved weeds were the most common weed group in the survey. Buckwheat (Polygonum convolvulus L.), lamb’s quarters (Chenopodium album L.), stinkweed (Thlaspi arvense L.), and wild mustard (Sinapis arvensis L.) were four of the six most abundant weeds in the organic survey. These results are opposite to the trend seen in conventional production where annual broad-leaves have become less abundant according to the surveys conducted from 1976 to 1995 (Thomas, 1996)

A calibration method for broad-bandwidth cavity enhanced absorption spectroscopy performed with supercontinuum radiation

An efficient calibration method has been developed for broad-bandwidth cavity enhanced absorption spectroscopy. The calibration is performed using phase shift cavity ring-down spectroscopy, which is conveniently implemented through use of an acousto-optic tunable filter (AOTF). The AOTF permits a narrowband portion of the SC spectrum to be scanned over the full high-reflectivity bandwidth of the cavity mirrors. After calibration the AOTF is switched off and broad-bandwidth CEAS can be performed with the same light source without any loss of alignment to the set-up. We demonstrate the merits of the method by probing transitions of oxygen molecules O-2 and collisional pairs of oxygen molecules (O-2)(2) in the visible spectral range

Doppler cooling of Ca+ ions in a Penning trap

Published versio

Nucleation of a sodium droplet on C60

We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1<=n<=30, we find that Na_nC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n=>8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.Comment: 17 pages, 10 figure

Psychology and aggression

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68264/2/10.1177_002200275900300301.pd