109 research outputs found
How hungry is hemp for fertilizers?
Non-Peer ReviewedA field experiment was conducted at Melfort, SK in 2000 and 2001 to determine the effects of nitrogen and phosphorus fertilizer rates on hemp (Cannabis sativa L.) productivity. Increased nitrogen fertilizer rates significantly increased seed yield and biomass production of hemp. The application of seed-placed phosphorus fertilizer, on the other hand, significantly reduced emergence, seed yield and biomass production in a dry year
Plant population and weed control in hemp production
Non-Peer ReviewedA field experiment was conducted at Melfort, SK in 2000 and 2001 to determine the effects of seeding rate and row spacing on oilseed hemp (Cannabis sativa L.) production. High seeding rates significantly reduced weed infestation, and increased seed yield and biomass production of hemp. Narrow row spacing reduced weed infestation only in 2000 (wet), and did not have any significant effect on seed yield or biomass production in either year
Footrot and interdigital dermatitis in sheep: Farmer satisfaction with current management, their ideal management and sources used to adopt new strategies
The aims of this research were to identify management practices that sheep farmers currently use to treat and prevent footrot in sheep and whether they consider that these are successful management tools and to find out how sheep farmers would ideally like to manage footrot in their flock. Over 90% of lameness in sheep in the UK is caused by Dichelobacter nodosus, which presents clinically as interdigital dermatitis (ID) alone or with separation of hoof horn (FR). A questionnaire was sent to 265 farmers to investigate their current management and their satisfaction with current management of the spectrum of clinical presentations of footrot. Farmers were also asked their ideal management of footrot and their interest in, and sources of information for, change. Approximately 160 farmers responded. Farmers satisfied with current management reported a prevalence of lameness â€5%. These farmers caught and treated lame sheep within 3 days of first seeing them lame, and treated sheep with FR and ID with parenteral antibacterials. Farmers dissatisfied with their management reported a prevalence of lameness >5%. These farmers practised routine foot trimming, footbathing and vaccination against footrot. Whilst 89% of farmers said they were satisfied with their management of FR over 34% were interested in changing management. Farmers identified veterinarians as the most influential source for new information. Farmers reported that ideally they would control FR by culling/isolating lame sheep, sourcing replacements from non-lame parents, trimming feet less, using antibacterial treatments less and using vaccination more. Footbathing was a commonly used management that was linked with dissatisfaction and that also was listed highly as an ideal management. Consequently, some of the ideal managements are in agreement with our understanding of disease control (culling and isolation, sourcing healthy replacements) but others are in contrast with our current knowledge of management and farmers self-reporting of satisfaction of management of footrot (less use of antibacterial treatment, more footbathing and vaccination). One explanation for this is the theory of cognitive dissonance where belief follows behaviour, i.e. farmers report that they believe an ideal which is what they are currently doing, even if the management is sub-optimal
X-Ray Polarization of Solar Flares Measured with Rhessi
The degree of linear polarization in solar flares has not yet been precisely
determined despite multiple attempts to measure it with different missions. The
high energy range in particular has very rarely been explored, due to its
greater instrumental difficulties. We approached the subject using the Reuven
Ramaty High Energy Spectroscopic Imager (RHESSI) satellite to study 6 X-class
and 1 M-class flares in the energy range between 100 keV and 350 keV. Using
RHESSI as a polarimeter requires the application of strict cuts to the event
list in order to extract those photons that are Compton scattered between two
detectors. Our measurements show polarization values between 2% and 54%, with
errors ranging from 10% to 26% in 1 sigma level. In view of the large
uncertainties in both the magnitude and direction of the polarization vector,
the results can only reject source models with extreme properties.Comment: 26 pages, 11 figures, accepted for publication by Solar Physic
Model reference adaptive control of a nonsmooth dynamical system
In this paper a modiïŹed model reference adaptive control (MRAC) technique is presented which can be
used to control systems with nonsmooth characteristics. Using unmodiïŹed MRAC on (noisy) nonsmooth
systems leads to destabilization of the controller. A localized analysis is presented which shows that the
mechanism behind this behavior is the presence of a time invariant zero eigenvalue in the system. The
modiïŹed algorithm is designed to eliminate this zero eigenvalue, making all the system eigenvalues stable.
Both the modiïŹed and unmodiïŹed strategies are applied to an experimental system with a nonsmooth
deadzone characteristic. As expected the unmodiïŹed algorithm cannot control the system, whereas the
modiïŹed algorithm gives stable robust control, which has signiïŹcantly improved performance over linear
ïŹxed gain control
Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO
Liquid xenon time projection chambers are promising detectors to search for
neutrinoless double beta decay (0), due to their response
uniformity, monolithic sensitive volume, scalability to large target masses,
and suitability for extremely low background operations. The nEXO collaboration
has designed a tonne-scale time projection chamber that aims to search for
0 of \ce{^{136}Xe} with projected half-life sensitivity of
~yr. To reach this sensitivity, the design goal for nEXO is
1\% energy resolution at the decay -value (~keV).
Reaching this resolution requires the efficient collection of both the
ionization and scintillation produced in the detector. The nEXO design employs
Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm
scintillation light of liquid xenon. This paper reports on the characterization
of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3
SiPMs specifically designed for nEXO, as well as new measurements on new test
samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters
(MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct
crosstalk, correlated avalanches and photon detection efficiency were measured
as a function of the applied over voltage and wavelength at liquid xenon
temperature (163~K). The results from this study are used to provide updated
estimates of the achievable energy resolution at the decay -value for the
nEXO design
Effects of temperature at constant air dew point on leaf carboxylation efficiency and CO 2 compensation point of different leaf types
The effect of temperature on photosynthesis at constant water-vapor pressure in the air was investigated using two sclerophyll species, Arbutus unedo and Quercus suber , and one mesophytic species, Spinacia oleracea . Photosynthesis and transpiration were measured over a range of temperatures, 20â39° C. The external concentration of CO 2 was varied from 340 ÎŒbar to near CO 2 compensation. The initial slope (carboxylation efficiency, CE) of the photosynthetic response to intercellular CO 2 concentration, the CO 2 compensation point (Î), and the extrapolated rate of CO 2 released into CO 2 -free air ( R i ) were calculated. At an external CO 2 concentration of 320â340 ÎŒbar CO 2 , photosynthesis decreased with temperature in all species. The effect of temperature on Î was similar in all species. While CE in S. oleracea changed little with temperature, CE decreased by 50% in Q. suber as temperature increased from 25 to 34° C. Arbutus unedo also exhibited a decrease in CE at higher temperatures but not as marked as Q. suber . The absolut value of R i increased with temperature in S. oleracea , while changing little or decreasing in the sclerophylls. Variations in Î and R i of the sclerophyll species are not consistent with greater increase of respiration with temperature in the light in these species compared with S. oleracea .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47470/1/425_2004_Article_BF00397389.pd
A Germline Variant at 8q24 Contributes to Familial Clustering of Prostate Cancer in Men of African Ancestry
Although men of African ancestry have a high risk of prostate cancer (PCa), no genes or mutations have been identified that contribute to familial clustering of PCa in this population. We investigated whether the African ancestryâspecific PCa risk variant at 8q24, rs72725854, is enriched in men with a PCa family history in 9052 cases, 143 cases from high-risk families, and 8595 controls of African ancestry. We found the risk allele to be significantly associated with earlier age at diagnosis, more aggressive disease, and enriched in men with a PCa family history (32% of high-risk familial cases carried the variant vs 23% of cases without a family history and 12% of controls). For cases with two or more first-degree relatives with PCa who had at least one family member diagnosed at age <60 yr, the odds ratios for TA heterozygotes and TT homozygotes were 3.92 (95% confidence interval [CI] = 2.13â7.22) and 33.41 (95% CI = 10.86â102.84), respectively. Among men with a PCa family history, the absolute risk by age 60 yr reached 21% (95% CI = 17â25%) for TA heterozygotes and 38% (95% CI = 13â65%) for TT homozygotes. We estimate that in men of African ancestry, rs72725854 accounts for 32% of the total familial risk explained by all known PCa risk variants. Patient summary: We found that rs72725854, an African ancestryâspecific risk variant, is more common in men with a family history of prostate cancer and in those diagnosed with prostate cancer at younger ages. Men of African ancestry may benefit from the knowledge of their carrier status for this genetic risk variant to guide decisions about prostate cancer screening. © 2020 The AuthorsThe African ancestryâspecific prostate cancer risk variant at 8q24, rs72725854, is enriched in men diagnosed at younger ages and men with a prostate cancer family history. Carriers of this risk allele would benefit from regular and earlier prostate cancer screening
A História da Alimentação: balizas historiogråficas
Os M. pretenderam traçar um quadro da HistĂłria da Alimentação, nĂŁo como um novo ramo epistemolĂłgico da disciplina, mas como um campo em desenvolvimento de prĂĄticas e atividades especializadas, incluindo pesquisa, formação, publicaçÔes, associaçÔes, encontros acadĂȘmicos, etc. Um breve relato das condiçÔes em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biolĂłgica, a econĂŽmica, a social, a cultural e a filosĂłfica!, assim como da identificação das contribuiçÔes mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histĂłrica, foi ela organizada segundo critĂ©rios morfolĂłgicos. A seguir, alguns tĂłpicos importantes mereceram tratamento Ă parte: a fome, o alimento e o domĂnio religioso, as descobertas europĂ©ias e a difusĂŁo mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rĂĄpido balanço crĂtico da historiografia brasileira sobre o tema
Barriers and bottlenecks : a case study of the implementation of extension policy for enabling sustainable natural resource management in Queensland, Australia
Internationally, extension has been a support instrument used by governments and commercial interests for improving agricultural production for hundreds, if not thousands of years. The application of extension theory and practice for natural resource management (NRM) is a more recent undertaking. However, over the last 20+ years, agencies sponsoring extension services appear to have lost confidence in extensionâs ability to achieve desired outcomes. In Australia, Greg Leachâs PhD research has sought to understand the barriers and bottlenecks which have prevented the implementation of extension policy by the Queensland State Government. His research enquired into the institutionalisation of extension in Queensland, as well as approaches and mechanisms for negotiating extension policy at the national scale from 2000 to 2010. Learnings from the authorâs involvement in operationalising a network of extension leaders from across Australia, underpin broader recommendations on institutionalising extension policy, and advice for extension policy to aid achievement of NRM outcomes
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