Diffuse Knapweed (Centaurea diffusa) Seed Germination

Weed Science ◽  
2010 ◽  
Vol 58 (4) ◽  
pp. 369-373 ◽  
Author(s):  
Charlie D. Clements ◽  
Daniel Harmon ◽  
James A. Young
Keyword(s):  
Great Basin ◽  
Response Surfaces ◽  
Temperature Profiles ◽  
Safe Sites ◽  
Centaurea Diffusa ◽  
Temperature Regimes ◽  
Wide Range ◽  
Quadratic Response ◽  
Environmental Requirements ◽  
Diffuse Knapweed

The objective of this study was to define further the environmental requirements for safe sites for germination of diffuse knapweed achenes (seeds). Germination temperature profiles were developed for diffuse knapweed seeds collected from sites in the Great Basin and Colorado. Each profile consisted of seeds germinated at 55 constant or alternating temperatures from 0 through 40 C. The resulting germination was used to develop quadratic response surfaces with regression analysis. Some germination occurred from 71 to 96% of the temperature regimes, depending on the accession being tested. Maximum observed germination ranged from 85 to 98%. Optimum germination, defined as the maximum observed minus one half the confidence interval at the 0.01 level of probability, occurred at a wide range of temperatures from cold periods of 0 through 20 C, alternating with warm periods of 10 through 35 C. The temperature regimes that most frequently supported optimum germination were 5/25 C (5 C for 16 h and 25 C for 8 h in each 24-h period) and 10/25 C. Germination of diffuse knapweed seeds was generally higher at alternating than constant temperatures.

Quadratic Response Surface Analysis of Seed-Germination Trials

Weed Science ◽  
1982 ◽  
Vol 30 (4) ◽  
pp. 411-416 ◽  
Author(s):  
Raymond A. Evans ◽  
Debra A. Easi ◽  
Don N. Book ◽  
James A. Young
Keyword(s):  
Seed Germination ◽  
Response Surface ◽  
Surface Analysis ◽  
Response Surfaces ◽  
Response Surface Analysis ◽  
Temperature Regimes ◽  
Quadratic Response Surface ◽  
Regression Techniques ◽  
Quadratic Response ◽  
Multiple Comparison Procedures

Quadratic response surface analysis was applied to data of seed germination in relation to temperature. Analysis of these data is the comparing of several levels of quantitative factors. In such situations, multiple-comparison procedures, such as Duncan's multiple range test, are inappropriate. The data were the germination percentages of four species at 55 constant or alternating day and night temperature regimes. A quadratic response surface was developed for each species using multiple-regression techniques. Estimated germination values and their confidence limits were derived from the quadratic response surface of each species for each cold-period temperature through a series of warm-period temperatures. Many parameters were synthesized from the response surfaces to evaluate germination of the four species in relation to temperature. These comparisons form a statistically valid basis from which to select the most adapted plant species and predict the best time for planting or applying weed-control treatments.

scholarly journals The simulation model for a flood management by flood control facilities

2018 ◽  
Vol 245 ◽  
pp. 15002 ◽  
Author(s):  
Roman Davydov ◽  
Valery Antonov ◽  
Dmitry Molodtsov ◽  
Alexey Cheremisin ◽  
Vadim Korablev
Keyword(s):  
Mathematical Models ◽  
Flood Control ◽  
Flood Management ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Operating Characteristics ◽  
Hydro Power ◽  
Operation Modes ◽  
Wide Range ◽  
Environmental Requirements

The rapid spread of storm floods over large areas requires flood management throughout the river basin by the creation an innovative system of flood control facilities of various functional purposes distributed in the area. The central part of the system is the hydro system with hydro power plant. In addition, the flood control facilities on the side tributaries with self-regulating reservoir are included in the system. To assess the effect of controlling extreme water discharges by flood control facilities, it is necessary to develop special mathematical models reflecting the specifics of their operation. Unified mathematical models of the operation modes of a hydro complex with hydroelectric power station and flood control facility are created. They are implemented in a computer program that provides the ability to determine the main parameters and operating characteristics of hydro systems when performing multivariate calculations in a wide range of initial data. This makes possible specifying the parameters and operation modes of each hydro system with the current economic and environmental requirements, to assess the energy-economic and environmental consequences in the operation of the system of flood control facilities distributed in the area. The article analyses the results of the extreme water discharge’s regulation by the hydro system on the main river and flood control facilities on the side tributaries, considering environmental requirements.

Treatment of Arrhythmias by Radiofrequency Ablation

2013 ◽  
Author(s):  
M. Erol Ulucakli ◽  
Evan P. Sheehan
Keyword(s):  
Radiofrequency Ablation ◽  
Cardiac Tissue ◽  
Clinical Applications ◽  
Bioheat Transfer ◽  
Temperature Profiles ◽  
Cellular Injury ◽  
Rf Ablation ◽  
Transcatheter Therapy ◽  
Wide Range ◽  
Primary Modality

Radiofrequency ablation may be described as a thermal strategy to destroy tissue by increasing its temperature and causing irreversible cellular injury. Radiofrequency ablation is a relatively new modality which has found use in a wide range of medical applications and gained acceptance. RF ablation has been used to destroy tumors in the liver, prostate, breasts, lungs, kidneys, bones, and eyes. One of the early clinical applications was its use in treating supraventricular arrhythmias by selectively destroying cardiac tissue. Radiofrequency ablation has become established as the primary modality of transcatheter therapy for the treatment of symptomatic arrhythmias. Radiofrequency catheter ablation of cardiac arrhythmias was investigated using a finite-element based solution of the bioheat transfer equation. Spatial and temporal temperature profiles in the cardiac tissue were visualized.

Trajectory and Characteristics of Buoyancy and Momentum Dominated Horizontal Jet Flames From Circular and Elliptic Burners

2005 ◽  
Vol 128 (4) ◽  
pp. 300-310 ◽  
Author(s):  
Tracy Smith ◽  
Chendhil Periasamy ◽  
Benjamin Baird ◽  
S. R. Gollahalli
Keyword(s):  
Nitric Oxide ◽  
Reynolds Number ◽  
Flame Temperature ◽  
Major Axis ◽  
Equivalent Diameter ◽  
Flame Stability ◽  
Temperature Profiles ◽  
Burner Exit ◽  
Wide Range ◽  
Nitric Oxide Emissions

Relative effects of buoyancy and momentum on the characteristics of horizontally oriented circular (Circ) and elliptic (E) burner flames in a quiescent environment over a wide range of jet exit velocities are presented. The major axis of the elliptic burner was oriented horizontally and vertically (referred to as Emaj and Emin flames, respectively). Propane was used as fuel and a small amount of hydrogen was piloted to attach flames to the burner. Global flame characteristics such as flame dimensions, centerline trajectory, emission indices (EI) and radiative fraction, and in-flame transverse concentration and temperature profiles were measured. At a jet exit Reynolds number (Rej) of 2000, based on the area-equivalent diameter of the burner, the flame characteristics were affected by the burner geometry and its orientation. Also, the vertical dimension of the burner exit dictated buoyancy effects. At Rej=12,500, the influence of burner geometry or its orientation was negligible. Elliptic burner flames exhibited lower liftoff and blowout velocities than circular burner flames. Furthermore, the flame stability and nitric oxide emissions were not much affected by the orientation of elliptic burner. Although the elliptic burners produced higher EINO at lower jet exit velocities, the variation in EINO among three burners (Circ, Emaj, and Emin) was insignificant at higher velocities. Some effects of buoyancy on EICO were observed at lower jet exit velocities and the EICO was the lowest for the burners with largest buoyancy flux. Elliptic burner flames produced greater peak flame temperature than the corresponding circular burner flames under most conditions.

scholarly journals Development of Drift-Reducing Spouts For Vineyard Pneumatic Sprayers: Measurement of Droplet Size Spectra Generated and Their Classification

2020 ◽  
Vol 10 (21) ◽  
pp. 7826
Author(s):  
Marco Grella ◽  
Antonio Miranda-Fuentes ◽  
Paolo Marucco ◽  
Paolo Balsari ◽  
Fabrizio Gioelli
Keyword(s):  
Droplet Size ◽  
Marked Reduction ◽  
Reduction Potential ◽  
Liquid Flow Rate ◽  
Spray Drift ◽  
Spray Application ◽  
Size Spectra ◽  
Wide Range ◽  
Environmental Requirements ◽  
Low Drift

Pneumatic spraying is especially sensitive to spray drift due to the production of small droplets that can be easily blown away from the treated field by the wind. Two prototypes of environmentally friendly pneumatic spouts were developed. The present work aims to check the effect of the spout modifications on the spray quality, to test the convenience of setting the liquid hose out of the spout in cannon-type and hand-type pneumatic nozzles and its effect on the droplet size, homogeneity and driftability in laboratory conditions. Laboratory trials simulating a real sprayer were conducted to test the influence of the hose insertion position (HP), including conventional (CP), alternative (AP), outer (OP) and extreme (XP), as well as the liquid flow rate (LFR) and the airflow speed (AS) on the droplet size (D50, D10 and D90), homogeneity and driftability (V100). Concurrently, the droplet size spectra obtained by the combination of aforementioned parameters (HP × LFR × AS) in both nozzles were also classified according to the ASABE S572.1. Results showed a marked reduction of AS outside the air spout, which led to droplet size increase. This hypothesis was confirmed by the droplet size spectra measured (D50, D10, D90 and V100). A clear influence of HP was found on every dependent variable, including those related with the droplet size. In both nozzles, the longer the distance to CP, the coarser the sprayed drops. Moreover, LFR and AS significantly increased and reduced droplet size, respectively. A higher heterogeneity in the generated drops was obtained in XP. This position yielded V100 values similar to those of the hydraulic low-drift nozzles, showing an effective drift reduction potential. The classification underlines that the variation of HP, alongside AS and LFR, allowed varying the spray quality from very fine to coarse/very coarse, providing farmers with a wide range of options to match the drift-reducing environmental requirements and the treatment specifications for every spray application.

Quenching rates and critical densities of c-C3H2

2019 ◽  
Vol 15 (S350) ◽  
pp. 148-151
Author(s):  
Malek Ben Khalifa ◽  
Emna Sahnoun ◽  
Silvia Spezzano ◽  
Laurent Wiesenfeld ◽  
Kamel Hammami ◽  
...  
Keyword(s):  
Potential Energy Surfaces ◽  
Full Potential ◽  
Thermodynamical Equilibrium ◽  
Medium Temperature ◽  
Permanent Electric Dipole Moment ◽  
Temperature Regimes ◽  
Wide Range ◽  
History Of ◽  
Energy Surfaces ◽  
Local Thermodynamical Equilibrium

AbstractCyclopropenylidene,, is a simple hydrocarbon, ubiquitous in astrophysical gases, and possessing a permanent electric dipole moment. Its readily observed multifrequency rotational transitions make it an excellent probe for the physics and history of interstellar matter. The collisional properties of with He are presented here. We computed the full Potential Energy Surfaces, and we perform quantum scattering in order to provide rates of quenching and excitation for low to medium temperature regimes. We discuss issues with the validity of the usual Local Thermodynamical Equilibrium assumption, and also the intricacies of the spectroscopy of an asymmetric top. We present the wide range of actual critical densities, as recently observed.

Contrasting Responses of Morphologically Similar Wheat Cultivars to Temperatures Appropriate to Warm Temperature Climates With Hot Summers: a Study in Controlled Environment

1977 ◽  
Vol 4 (6) ◽  
pp. 877 ◽  
Author(s):  
AK Bagga ◽  
HM Rawson
Keyword(s):  
Temperature Stability ◽  
Kernel Weight ◽  
Controlled Environment ◽  
Wheat Cultivars ◽  
Warm Temperature ◽  
Temperature Regimes ◽  
Wide Range ◽  
Phase Temperature ◽  
Warm Temperate ◽  
Plant Basis

This study attempted to determine if and why there are differences among three cultivars of wheat in their responses to temperature. The three semidwarf cultivars examined, Kalyansona, Condor and Janak, are currently used commercially. Temperature regimes chosen matched the range to which plants in warm temperate climates with hot summers would be exposed at different stages of development. Plants were grown in a phytotron in sunlit cabinets. Responses to temperature were different among the cultivars. Kalyansona was relatively un- responsive to temperatures during the floret phase, being little affected in the sizes of upper leaves, in floret production and grain set, in overall plant growth or in grain yield. The sole character to respond to temperature in this cultivar was kernel weight, which declined with increasing grain phase temperature. In contrast, Condor demonstrated marked plasticity during the floret phase in all plant characters measured. Its plasticity was such that, at the lower temperatures, it outyielded Kalyansona by a substantial margin while at the higher temperatures its yield was relatively poor. On a plant basis, Janak performed similarly to Condor. Rates of photosynthesis were relatively unaffected by temperature in any cultivar. This wide range of response among three superficially similar cultivars has promising implications for the tailoring of cultivars for different temperature zones. The importance of different plant characters to temperature stability is considered in the discussion.

A response surface approach to examining the use of separated milk and wheat by growing pigs

1969 ◽  
Vol 9 (37) ◽  
pp. 121 ◽  
Author(s):  
JM Holder ◽  
BR Wilson ◽  
RJ Williams
Keyword(s):  
Response Surface ◽  
Response Surfaces ◽  
Growing Pigs ◽  
Feed Conversion ◽  
Surface Approach ◽  
Production Factors ◽  
Wide Range ◽  
Minimum Expenditure ◽  
Dietary Treatments ◽  
Research Facilities

Response surfaces were examined relating inputs of separated milk and wheat to liveweight gain, efficiency of feed conversion, and carcase composition of pigs growing to pork or bacon weights. Twenty-eight different dietary treatments were examined in eight separate experiments. Diets ranged from all separated milk to all wheat, and in each experiment levels of feeding ranged from two to five per cent of body weight. A total of 128 individually fed pigs were used. As levels of feeding increased, daily gains increased, dissectible lean decreased, but there was no consistent effect on efficiency of feed conversion. The exception was where the quality and quantity of protein ingested limited growth rate, and under these circumstances feed efficiency tended to worsen. Desirable production factors were not necessarily associated with any one treatment. Although high daily gains meant that pigs were marketed earlier, carcases produced in this way were fat and not as valuable as those pigs grown more slowly. It was concluded that the response surface approach offers a method of examining a wide range of inputoutput relationships with a minimum expenditure of research facilities.

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