549 research outputs found
Spring wheat rotations in north-central Saskatchewan
Non-Peer ReviewedEffects of rotation length, crop sequence, and fertilization on yields and economic performance of 10 spring wheat-based rotations are examined over a 27-year period (1960-86) on an Orthic Black Chernozem at Melfort, Saskatchewan. The silty clay loam soil had an initial organic N content of about 0.55 % (0-15 cm depth). During 1960-71, fertilized plots received N and P based on general recommendations for the region; thereafter, fertilizer was applied based on soil tests. Yields of wheat grown on fertilized fallow were similar for F-W, F-W-W and a 6-yr fallow-wheat-legume hay (F-W-W-H-H-W) rotation (avg 2519 kg ha-1 in 1960-71 and 3036 kg ha-1 in the wetter 1972-86 period). Fertilized stubble wheat yields in a F-W-W rotation
averaged 88 % of comparable fallow wheat yields, while continuous wheat averaged only 66 % due to greater weed and disease problems. Inclusion of grass-legume hay or legume green manure crops in the rotations provided no yield benefit for subsequent wheat crops in this fertile soil. Results of the economic analysis showed that at wheat prices greater than $147 t-1, fertilized F-W-W, F-C-W and F-W-W-H-H-W generally provided the best overall economic return. At lower wheat prices unfertilized F-W-W and F-W-W-H-H-W, and fertilized F-W often provided the highest net income. It was profitable to substitute canola for wheat grown on conventional fallow or on partial fallow after grass-legume hay when the ratio of canola to wheat price was greater than about 2.0. Similarly, it was profitable to include grass-legume hay in wheat rotations when the hay price was greater than about one-half that of wheat. Continuous wheat and legume green manure rotation were not economically competitive with the best rotations at any of the
price options examined. Fertilizer application was profitable in the F-W-W and continuous wheat rotations when the ratio of fertilizer N cost to wheat price was less than about 5.0; it was profitable in F-W-W-H-H-W when this ratio was less than 3.5. The cost of producing wheat, income variability, and the frequency of economic losses increased with cropping intensity
Cellular eIF2B subunit localisation: implications for the integrated stress response and its control by small molecule drugs
eIF2 is a G protein critical for translation. It is tightly regulated in the integrated stress response (ISR) via phosphorylation of eIF2α and the subsequent control of eIF2B, a multisubunit guanine nucleotide exchange factor (GEF). Through studying the localisation of eIF2B subunits we identified cytoplasmic eIF2B bodies in mammalian cells. We highlight a relationship between body size and the eIF2B subunits localising to them; larger bodies contain all subunits and smaller bodies contain predominantly catalytic subunits. eIF2 localises to eIF2B bodies and shuttles within these bodies in a manner which correlates with eIF2B activity. Upon stress eIF2α-P localises predominately to larger bodies and results in a decreased shuttling of eIF2. Interestingly drugs which inhibit the ISR can rescue eIF2 shuttling in a manner correlating to levels of eIF2α-P. In contrast, smaller bodies show increased eIF2 shuttling in response to stress, which is accompanied by the localisation of eIF2Bδ to these bodies, suggesting the formation of a novel trimeric complex of eIF2B. This response is mimicked by ISR inhibiting drugs, providing insight into their potential mechanism of action. This study provides evidence that the composition and function of mammalian eIF2B bodies is regulated by the ISR and drugs which control it
The long-term agronomic and economic effects of crop rotations in western Canada
Non-Peer ReviewedAgriculture Canada Research Stations in western Canada have conducted more than 68 long-term crop rotation experiments since the early 1900's; twenty of these are still ongoing. A committee of scientists, representing all Research Stations on the Prairies has just completed an in-depth review and summary of the major findings from these studies. Based on their findings, they also developed recommendations that can be used by managers in decision making and rationalization of resource use for current and future
studies of this kind. The resulting two publications which will be released in early 1990 include: i) a bulletin entitled 'Benefits of Crop Rotation for Sustainable Agriculture in Dryland Farming', 'Which presents producer recommendations on how to run an efficient, economical, and environmentally responsible cropping operation, and ii) a detailed technical book entitled 'Crop Rotation Studies on the Canadian Prairies', which is directed at the scientific community but is also useful for extension personnel and producers. This paper highlights some of the main aspects reported in these publications and attempts to give a coherent and broader interpretation of the underlying principles and processes of crop production. The discussion focuses on the effects of rotation length, crop sequence, substitutes for summerfallow, and N and P fertilizer, on crop production, grain and forage quality, soil moisture conservation and moisture use efficiency, N and P uptake by the plants, nutrient losses, soil quality, profitability, nonrenewable energy efficiency, and crop pests
Water conservation under reduced tillage systems
Water is important for dryland crop production. Seldom is rainfall
sufficient or adequately distributed during a growing season so that dryland
crops can produce to their fullest potential. It is necessary to have
stored water available in the soil to supplement inadequate growing season
rainfall for economical crop production. Stored water is especially
important in the Inland Pacific Northwest of north central Oregon,
southeastern Washington, and northern Idaho, where 65% of annual
precipitation occurs during the six-month (Sept. 1 to Feb. 28) winter period
and 30% during the four-month (March 1 to June 30) growing season. Stored
water is also important in the Eastern Idaho Plateau where the low annual
precipitation is nearly evenly distributed over the months of the year.
The water balance equation tells us that change in water content in the
soil - precipitation + inflow - runoff + upward flow - drainage -
evapotranspiration (ET). Any cultural practice that decreases runoff or ET
can result in increased water in the soil. To store adequate quantities
of water, deep soils (> 60 inches) with good infiltration and water holding
capacity are required. Summer fallow has long been the traditional practice
for storing water in soils for later use by crops. Fallow periods vary from
14 to 15 months where winter small grains are seeded to 21 months where
spring small grains are seeded. Water storage efficiency for fallow is low,
ranging from 10 to 35% in the Great Plains and the Southwest; to 30-37% in
eastern Idaho and northern Utah; to 40-45% of precipitation in the Inland
Pacific Northwest (Evans and Lemon, 1957). Good water conservation yields
increased crop production, stability of production, and increased water use
efficiency. Soil tillage and residue management play significant roles in
collection and storage of precipitation in the soil.
Our objectives are to discuss insights in water conservation gained under
the STEEP (Solutions to Economic and Environmental Problems) program
(Oldenstadt et al., 1982) during these last ten years and problems that
remain. New research information will be discussed under topics of crop
residues, conservation tillage systems, fallow and models
A comprehensive categorical and bibliometric analysis of published research articles on pediatric pain from 1975-2010
The field of pediatric pain research began in the mid-1970's and has undergone significant growth and development in recent years as evidenced by the variety of books, conferences, and journals on the topic as well as the number of disciplines engaged in work in this area. Using categorical and bibliometric meta-trend analysis, the current study offers a synthesis of research on pediatric pain published between
1975 and 2010 in peer-reviewed journals. Abstracts from 4256 articles, retrieved from Web of Science, were coded across four categories: article type, article topic, type and age of participants, and pain stimulus. The affiliation of the first author and number of citations were also gathered. The results suggest a significant increase in the number of publications over the time period investigated, with 96% of the included articles published since 1990 and most research being multi-authored publications in pain- focused journals. First authors were most often from the United States, and affiliated with a medical department. The majority of studies were original research articles; the most frequent topics were pain characterization (39.86%), pain intervention (37.49%), and pain assessment (25.00%). Clinical samples were most frequent, with participants most often characterized as children (6-12 years) or adolescents (13-18 years) experiencing chronic or acute pain. The findings provide a comprehensive overview of contributions in the field of pediatric pain research over 35 years and offers recommendations for future research in the area.
(C) 2015 International Association for the Study of Pai
Drug–drug Interaction between Pravastatin and Gemfibrozil (Antihyperlipidemic) with Gliclazide (Antidiabetic) in Rats
Diabetes mellitus is a condition of increased blood glucose level in the body. Antihyperlipidemic drugs like statins and fibrates are widely used for prophylactic treatment in dyslipideamia and atherosclerosis. Diabetic dislipidemia exists with increased triglycerides, low HDL and high LDL levels. Hence, with oral hypoglycemic drugs, the addition of a lipid-lowering drug is necessary for controlling dislipidemia. In such a situation, there may be chances of drug–drug interactions between antidiabetic and antihyperlipidemic drugs. The present study is planned to evaluate the safety of gliclazide (antidiabetic) in the presence of pravastatin and gemfibrozil (antihyperlpidemic) in rats. Studies in normal and alloxan-induced diabetic rats were conducted with oral doses of gliclazide and their combination with pravastatin and gemfibrozil, with an adequate washout period in between the treatments. Blood samples were collected in rats by retroorbital puncture at 0, 1, 2, 3, 4, 6, 8, 10 and 12 h. All the blood samples were analyzed for glucose by GOD –POD. Gliclazide (½ TD) produced hypoglycemic activity in normal and diabetic rats, with peak activity at 2 and 8 h. Pravastatin (TD) + gemfibrozil (TD) combination treatment increased the hypoglycemic effect of gliclazide in normal rats or diabetic rats when administered together. The interaction observed due to inhibition of both the enzymes (CYP 450 2C9 and CYP 450 3A4) responsible for the metabolism of gliclazide showed increased half-life, which was seen in the present study. Because concomitant administration of gliclazide with provastatin and gemfibrozil in diabetes is associated with atherosclerosis, it should be contraindicated or used with caution
Appraising empirical applications of Structuration Theory in management and organization studies
There is an increasing interest in the application of Structuration Theory in the fields of management and organization studies. Based upon a thorough literature review, we have come up with a data-set to assess how Structuration Theory has been used in empirical research. We use three key concepts of this theory (duality of structure, knowledgeability, and time-space) as sensitizing concepts for our analysis. We conclude that the greatest potential of Structuration Theory for management and organization studies is to view it as a process theory that offers a distinct building block for explaining intra and interorganizational change, as exemplified through concepts such as routine, script, genre, practice, and discourse
HiggsBounds: Confronting Arbitrary Higgs Sectors with Exclusion Bounds from LEP and the Tevatron
HiggsBounds is a computer code that tests theoretical predictions of models
with arbitrary Higgs sectors against the exclusion bounds obtained from the
Higgs searches at LEP and the Tevatron. The included experimental information
comprises exclusion bounds at 95% C.L. on topological cross sections. In order
to determine which search topology has the highest exclusion power, the program
also includes, for each topology, information from the experiments on the
expected exclusion bound, which would have been observed in case of a pure
background distribution. Using the predictions of the desired model provided by
the user as input, HiggsBounds determines the most sensitive channel and tests
whether the considered parameter point is excluded at the 95% C.L. HiggsBounds
is available as a Fortran 77 and Fortran 90 code. The code can be invoked as a
command line version, a subroutine version and an online version. Examples of
exclusion bounds obtained with HiggsBounds are discussed for the Standard
Model, for a model with a fourth generation of quarks and leptons and for the
Minimal Supersymmetric Standard Model with and without CP-violation. The
experimental information on the exclusion bounds currently implemented in
HiggsBounds will be updated as new results from the Higgs searches become
available.Comment: 64 pages, 15 tables, 8 figures; three typos which made it to the
published version corrected; the code (currently version 3.0.0beta including
LHC Higgs search results) is available via:
http://projects.hepforge.org/higgsbounds
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