Modelling the Adoption of Crop Rotation Practices in Organic Mixed Farms

Taylor et al. (2001) noted that well designed rotations are fundamental to organic farming systems. Rotations help organic systems achieve a balance between crops which deplete fertility, in particular nitrogen, and soil organic matter, and crops which restore fertility. The paper discusses the choice of crop rotation in the context of organic mixed farm systems that include cereals and livestock. The analysis is performed by combining economics and biology with the intention of capturing a broader approach to measuring the resilience of farming systems. Thus, it considers that the farmer’s choice of a specific rotation is based on the expected economic return derived from the rotation, and also the biological benefits provided by the selected rotation. The analysis is based on organic crop rotation trials ran from 1991 to 2006 at a site in the north-east of Scotland (Tulloch, Aberdeen) (Taylor et al., 2006).Crop Production/Industries, Farm Management,

A Comparison of Two Formulas of Topical Menthol on Vascular Responses and Perceived Intensity Prior to and following a Bout of Maximum Voluntary Muscular Contractions (MVMCs)

The purpose of this study was to compare the vascular responses in the brachial artery and perceived intensity of two different formulas of topical menthol gels prior to and following a bout of maximum voluntary muscular contractions (MVMCs). 18 adults completed the same protocol on different days using blinded topical menthol gels (Old Formula and New Formula). Heart rate, brachial artery blood flow (ml/min), vessel diameter and reported intensity of sensation were measured at baseline (T1), at 5 min after application of the gel to the upper arm (T2), and immediately following five MVMCs hand grips (T3). The New Formula exhibited a significant decline in blood flow (−22.6%) between T1 and T2 which was not different than the nonsignificant declines under the Old Formula 1 (−21.8%). Both formulas resulted in a significant increase in perceived intensity of sensation between T1 and T2. Blood flow increased significantly with the New Formula (488%) between T2 and T3 and nonsignificantly with the Old Formula (355%)

Results of the tagging of salt water fishes in Florida

The purpose of this paper is to report the results to date (October 1, 1961) of the 1960-61 fish-tagging program conducted in Zone I (Northern Hernando County Line to Everglades City)along the southwest coast of Florida and Zone II (Everglades City to the northern Indian River County Line.) (66pp.

Internal Friction of Amorphous Silicon in a Magnetic Field

The internal friction of e-beam amorphous silicon was measured in a magnetic field between 0 and 6 T, from 1.5-20 K, and was found to be independent of the field to better than 8%. It is concluded that the low energy excitations observed in this experiment are predominantly atomic in nature.Comment: 4 pages, 4 figures, REVTe

Spin Wave Diffraction and Perfect Imaging of a Grating

We study the diffraction of Damon-Eshbach-type spin waves incident on a one-dimensional grating realized by micro slits in a thin permalloy film. By means of time-resolved scanning Kerr microscopy we observe unique diffraction patterns behind the grating which exhibit replications of the spin-wave field at the slits. We show that these spin-wave images, with details finer than the wavelength of the incident Damon-Eshbach spin wavelength, arise from the strongly anisotropic spin wave dispersion.Comment: 5 pages, 3 figure

Prof-in-a-Box: using internet-videoconferencing to assist students in the gross anatomy laboratory

BACKGROUND: The optimal learning environment for gross anatomy is the dissection laboratory. The Prof-in-a-Box (PiB) system has been developed where an anatomist using distance-learning technologies 'helps' students in a dissection laboratory at a different site. METHODS: The PiB system consists of: (1) an anatomist in his/her office with a computer and video camera; (2) a computer and 2 video cameras in the lab; (3) iChat AV software; (4) a secure server to host the PiB-student 'consultation'. The PiB system allows the students and faculty to interact via audio and video providing an environment where questions can be asked and answered and anatomical structures can be identified 'at a distance' in real-time. The PiB system was set up at a prosected cadaver and made available for student use during 'office hours'. RESULTS: 25–30% of the students used the PiB system. Anatomical structures were identified, questions answered and demonstrations given 'at a distance' using the system. Students completed an optional questionnaire about the PiB system at the end of the semester. Results of the questionnaire indicate that the students were enthusiastic about the PiB system and wanted its use to be expanded in the future. CONCLUSION: Many of the functions of a faculty member in the gross anatomy dissection laboratory can be performed 'at a distance' using the PiB system. This suggests that a geographically dispersed faculty could assist in providing instruction in the dissection labs at multiple medical schools without needing to be physically present

Flatfishes (Pleuronectiformes)

Document has 135 pages

Longitudinal characterization of antimicrobial resistance genes in feces shed from cattle fed different subtherapeutic antibiotics

<p>Abstract</p> <p>Background</p> <p>Environmental transmission of antimicrobial-resistant bacteria and resistance gene determinants originating from livestock is affected by their persistence in agricultural-related matrices. This study investigated the effects of administering subtherapeutic concentrations of antimicrobials to beef cattle on the abundance and persistence of resistance genes within the microbial community of fecal deposits. Cattle (three pens per treatment, 10 steers per pen) were administered chlortetracycline, chlortetracycline plus sulfamethazine, tylosin, or no antimicrobials (control). Model fecal deposits (<it>n </it>= 3) were prepared by mixing fresh feces from each pen into a single composite sample. Real-time PCR was used to measure concentrations of <it>tet</it>, <it>sul </it>and <it>erm </it>resistance genes in DNA extracted from composites over 175 days of environmental exposure in the field. The microbial communities were analyzed by quantification and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified <it>16S-rRNA.</it></p> <p>Results</p> <p>The concentrations of <it>16S-rRNA </it>in feces were similar across treatments and increased by day 56, declining thereafter. DGGE profiles of <it>16S-rRNA </it>differed amongst treatments and with time, illustrating temporal shifts in microbial communities. All measured resistance gene determinants were quantifiable in feces after 175 days. Antimicrobial treatment differentially affected the abundance of certain resistance genes but generally not their persistence. In the first 56 days, concentrations of <it>tet</it>(B), <it>tet</it>(C), <it>sul1, sul2</it>, <it>erm</it>(A) tended to increase, and decline thereafter, whereas <it>tet</it>(M) and <it>tet</it>(W) gradually declined over 175 days. At day 7, the concentration of <it>erm</it>(X) was greatest in feces from cattle fed tylosin, compared to all other treatments.</p> <p>Conclusion</p> <p>The abundance of genes coding for antimicrobial resistance in bovine feces can be affected by inclusion of antibiotics in the feed. Resistance genes can persist in feces from cattle beyond 175 days with concentrations of some genes increasing with time. Management practices that accelerate DNA degradation such as frequent land application or composting of manure may reduce the extent to which bovine feces serves as a reservoir of antimicrobial resistance.</p