scholarly journals Eddy Heat Conduction and Nonlinear Stability of a Darcy Lapwood System Analysed by the Finite Spectral Method

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jónas Elíasson
Keyword(s):  
Fourier Transform ◽  
Heat Conduction ◽  
Nonlinear Stability ◽  
Growth Rates ◽  
Fluid Velocity ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Wave Number ◽  
Nonlinear Growth ◽  
Finite Spectral Method

A finite Fourier transform is used to perform both linear and nonlinear stability analyses of a Darcy-Lapwood system of convective rolls. The method shows how many modes are unstable, the wave number instability band within each mode, the maximum growth rate (most critical) wave numbers on each mode, and the nonlinear growth rates for each amplitude as a function of the porous Rayleigh number. Single amplitude controls the nonlinear growth rates and thereby the physical flow rate and fluid velocity, on each mode. They are called the flak amplitudes. A discrete Fourier transform is used for numerical simulations and here frequency combinations appear that the traditional cut-off infinite transforms do not have. The discrete show a stationary solution in the weak instability phase, but when carried past 2 unstable modes they show fluctuating motion where all amplitudes except the flak may be zero on the average. This leads to a flak amplitude scaling process of the heat conduction, producing an eddy heat conduction coefficient where a Nu-RaLrelationship is found. It fits better to experiments than previously found solutions but is lower than experiments.

Reassessment of Maximum Growth Rates for C3 and C4 Crops

1978 ◽  
Vol 14 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Monteith
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growing Season ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Crop Growth ◽  
Close Inspection ◽  
Similar Difference ◽  
Photosynthetic Efficiencies

SUMMARYFigures for maximum crop growth rates, reviewed by Gifford (1974), suggest that the productivity of C3 and C4 species is almost indistinguishable. However, close inspection of these figures at source and correspondence with several authors revealed a number of errors. When all unreliable figures were discarded, the maximum growth rate for C3 stands fell in the range 34–39 g m−2 d−1 compared with 50–54 g m−2 d−1 for C4 stands. Maximum growth rates averaged over the whole growing season showed a similar difference: 13 g m−2 d−1 for C3 and 22 g m−2 d−1 for C4. These figures correspond to photosynthetic efficiencies of approximately 1·4 and 2·0%.

scholarly journals Interactions Between the Kleptoplastidic Dinoflagellate Shimiella gracilenta and Several Common Heterotrophic Protists

2021 ◽  
Vol 8 ◽  
Author(s):  
Sang Ah Park ◽  
Hae Jin Jeong ◽  
Jin Hee Ok ◽  
Hee Chang Kang ◽  
Ji Hyun You ◽  
...  
Keyword(s):  
Growth Rates ◽  
Ingestion Rate ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Prey Concentration ◽  
Ingestion Rates ◽  
Oxyrrhis Marina ◽  
Planktonic Food ◽  
Moderate Growth ◽  
Algal Prey

The newly described dinoflagellate, Shimiella gracilenta, is known to survive for approximately 1 month on the plastids of ingested prey cells during starvation, indicating kleptoplastidy. To understand the population dynamics of this dinoflagellate in marine planktonic food webs, its growth and mortality rate due to predation should be assessed. Thus, we investigated the feeding occurrence of eight common heterotrophic protists on S. gracilenta. We also determined the growth and ingestion rates of Oxyrrhis marina and the naked ciliate, Rimostrombidium sp. on S. gracilenta as a function of the prey concentration. The common heterotrophic dinoflagellates (HTDs) Gyrodinium dominans, O. marina, and Pfiesteria piscicida and a naked ciliate Rimostrombidium sp. were able to feed on S. gracilenta; whereas the HTDs Aduncodinium glandula, Gyrodinium jinhaense, Oblea rotunda, and Polykrikos kofoidii were not. Shimiella gracilenta supported positive growth of O. marina and Rimostrombidium sp. but did not support that of G. dominans and P. piscicida. With increasing prey concentrations, the growth and ingestion rates of O. marina and Rimostrombidium sp. on S. gracilenta increased and became saturated. The maximum growth rates of O. marina and Rimostrombidium sp. on S. gracilenta were 0.645 and 0.903 day−1, respectively. Furthermore, the maximum ingestion rates of O. marina and Rimostrombidium sp. on S. gracilenta were 0.11 ng C predator day−1 (1.6 cells predator−1 day−1) and 35 ng C predator day−1 (500 cells predator−1 day−1), respectively. The maximum ingestion rate of O. marina on S. gracilenta was lower than that on any other algal prey reported to date, although its maximum growth rate was moderate. In conclusion, S. gracilenta had only a few common heterotrophic protist predators but could support moderate growth rates of the predators. Thus, S. gracilenta may not be a common prey species for diverse heterotrophic protists but may be a suitable prey for a few heterotrophic protists.

Kinetics And Morphology Of Homoepitaxial Cvd Growth On Diamond (100) And (111)

1995 ◽  
Vol 416 ◽  
Author(s):  
R. E. Rawles ◽  
W. G. Morris ◽  
M. P. D’Evelyn
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Chemical Vapor ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Arrhenius Behavior ◽  
Oriented Growth ◽  
Relative Growth Rates ◽  
Cvd Growth ◽  
Hot Filament

ABSTRACTGrowth rates for homoepitaxy of diamond (100) and (111) by hot-filament chemical vapor deposition were measured via in situ Fizeau interferometry and the surface morphologies were subsequently characterized by atomic force microscopy (AFM). (100)-oriented growth from 0.5% CH4 in H2 exhibited pure Arrhenius behavior, with an activation energy of 17±1 kcal/mol, up to a substrate temperature of 1100°C. Addition of oxygen to the feed gas resulted in an increased growth rate below 900°C, a maximum growth rate between 900 and 1000°C, and etching (of diamond) above 1050 - 1100°C. However, the presence of oxygen apparently had less effect on the surface morphology than did the (100)-to-(111) growth rate parameter α, determined directly from the relative growth rates of (100) and (111) substrates mounted side by side. During homoepitaxial growth from 0.5% CH4 in H2 at 875°C of ca. 1-micron-thick films,α = was 2.2 without oxygen and 1.3 for growth with 0.14% O2. The (100) film grown with α = 2.2 was quite smooth, while that with α = 1.3 was covered by numerous hillocks and penetration twins. AFM analysis revealed surprisingly little difference between the (111) films despite the considerable difference in α. Implications of these results for the growth mechanism are discussed.

Growth Rate Responses of Lotic Periphytic Diatoms to Experimental Phosphorus Enrichment: The Influence of Temperature and Light

1988 ◽  
Vol 45 (2) ◽  
pp. 261-270 ◽  
Author(s):  
Max L. Bothwell
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Phosphorus Enrichment ◽  
Enrichment Experiments ◽  
Community Growth ◽  
Specific Growth Rates ◽  
The Relationship ◽  
River Water Temperature

Phosphate enrichment experiments were conducted year-round at the experimental troughs research apparatus (EXTRA) on the South Thompson River in British Columbia to determine the relationship between external concentration of orthophosphate and the growth rates of lotic periphytic diatom communities. Growth rate saturation always occurred at a phosphate concentration of approximately 0.3–0.6 μg P∙L−1. The maximum growth rate (μmax-P) with phosphorus enrichment varied seasonally with temperature. The relative specific growth rates (μ:μmax-P) as a function of external phosphate were constant. Seasonal changes in solar insolation (PAR) had no effect on the autotrophic community growth rates in unamended river water. Temperature exerted the most dominant influence on phosphorus-replete growth rates.

scholarly journals Stability of an electrified liquid jet approaching to critical point

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402093637
Author(s):  
Zixuan Fang ◽  
Ping Wang
Keyword(s):  
Surface Tension ◽  
Critical Point ◽  
Weber Number ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Wave Number ◽  
Electrical Field ◽  
Electric Stress ◽  
Electrical Field Intensity ◽  
The Stability

This article reports the linear stability analysis of a thermodynamic-transcritical jet sprayed to a radial electrical field. An asymptotic approach was used to obtain the stability solution of a supercritical jet subjected to electrical field. In order to obtain the solutions for the electrified supercritical jet, the surface tension was decreased and consequently led the increase in Weber number in the linear governing equation of subcritical charged jet. To investigate the role of surface tension and electric stress playing in the destabilizing process when approaching the critical point, the energy budget is performed by tracing the energy sources. It was found that, when the Weber number is increased to a sufficiently large value, the solution will become an asymptotic value, which can be considered as a solution under the supercritical conditions. The electric stress can increase both the maximum growth rate and the dominant wave number of electrified supercritical jet, that is, higher electrical field intensity would enhance the instability of the electrified supercritical jet and decrease the wavelength of the disturbances.

scholarly journals Jeans Instability of Dissipative Self-Gravitating Bose–Einstein Condensates with Repulsive or Attractive Self-Interaction: Application to Dark Matter

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 226
Author(s):  
Pierre-Henri Chavanis
Keyword(s):  
Dark Matter ◽  
Scattering Length ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Einstein Condensate ◽  
Wave Number ◽  
Arbitrary Form ◽  
Bose Einstein Condensate ◽  
Jeans Instability ◽  
Bose Einstein

We study the Jeans instability of an infinite homogeneous dissipative self-gravitating Bose–Einstein condensate described by generalized Gross–Pitaevskii–Poisson equations [Chavanis, P.H. Eur. Phys. J. Plus2017, 132, 248]. This problem has applications in relation to the formation of dark matter halos in cosmology. We consider the case of a static and an expanding universe. We take into account an arbitrary form of repulsive or attractive self-interaction between the bosons (an attractive self-interaction being particularly relevant for the axion). We consider both gravitational and hydrodynamical (tachyonic) instabilities and determine the maximum growth rate of the instability and the corresponding wave number. We study how they depend on the scattering length of the bosons (or more generally on the squared speed of sound) and on the friction coefficient. Previously obtained results (notably in the dissipationless case) are recovered in particular limits of our study.

scholarly journals Asymmetric Modes of the Kelvin-Helmholtz Instability in Protostellar Jets

1997 ◽  
Vol 182 ◽  
pp. 323-333
Author(s):  
James M. Stone
Keyword(s):  
Growth Rate ◽  
Unstable Mode ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Nonlinear Regime ◽  
Helmholtz Instability ◽  
Nonlinear Growth ◽  
Protostellar Jets ◽  
Sinusoidal Oscillations ◽  
Ambient Gas

The results of a detailed analysis of the linear properties, nonlinear growth, and saturation of asymmetric modes of the Kelvin-Helmholtz instability in cooling protostellar jet beams are summarized. In the linear regime, cooling can significantly alter the growth rate and wavelength of the most unstable mode in comparison to an adiabatic jet. In the nonlinear regime, sinusoidal oscillations at the maximum growth rate lead to distortions that will be observed as ‘wiggles’ or ‘kinks’ in the jet. Strong cooling behind shocks formed in the nonlinear regime can produce emission knots and filaments. In some cases, the modes grow until the jet is disrupted. Distortions in the surface of the jet drive shock spurs into the ambient gas, resulting in longitudinal acceleration. Rapid acceleration and entrainment of ambient gas is also observed if the jet is disrupted.

Sizes and Growth-Rates of Thalli of the Lichen Rhizocarpon Geographicum on the Moraines of the Glacier De Valsorey, Valais, Switzerland

1983 ◽  
Vol 15 (3) ◽  
pp. 249-261 ◽  
Author(s):  
M. C. F. Proctor
Keyword(s):  
Growth Rates ◽  
Radial Growth ◽  
Growth Curves ◽  
Field Measurements ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Rhizocarpon Geographicum ◽  
Constant Rate ◽  
Maximum Parameters ◽  
Lichen Growth

AbstractMeasurements of thalli of Rhizocarpon geographicum on the recent moraines of the Glacier de Valsorey and their surroundings are considered in relation to thallus growth rates and colonization following glacial recession. Photographs taken in 1975 and 1979 show that up to c. 3.5 cm diam the relation of maximum growth-rate to thallus size is approximated by a growth curve of the kind derived by Aplin and Hill, rising asymptotically towards a constant rate of radial growth (here c. 0.5 mm year−1). Growth-rates of many individual thalli fall well below the maximum. Parameters of the fitted growth curves are used to construct curves of thallus radius against time. Taken in conjunction with the field measurements these suggest two main phases of colonization, one from about 1880 to 1910, and one from about 1930 onwards. Some general considerations relating to lichenometry and lichen growth curves are discussed.

Shoot and leaf growth in Fraxinuspennsylvanica and its relation to crown location and pruning

1994 ◽  
Vol 24 (10) ◽  
pp. 1997-2005 ◽  
Author(s):  
W.R. Remphrey ◽  
C.G. Davidson
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Leaf Growth ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Logistic Growth ◽  
Parameter Estimates ◽  
Regression Equations ◽  
Green Ash ◽  
Growth Duration

Elongation of shoots in various crown locations, and of individual internodes and leaves of the leading shoot, were recorded at 2-day intervals throughout the 1991 growing season in four clones of Fraxinuspennsylvanica var. subintegerrima (Vahl) Fern. (green ash). Other trees were disbudded and pruned to a single leader. Using a logistic growth function, nonlinear regression equations were generated and parameter estimates were used to determine maximum growth rates. Terminal leading shoots had a longer growth duration and a greater maximum growth rate than lateral shoots. The pruning treatment resulted in larger shoots, which grew 2–3 weeks longer and had a higher maximum growth rate. Leaf emergence occurred at regular intervals but the rate of emergence varied among clones. Leaf maximum growth rates were not significantly different among clones. Leaf size declined acropetally whereas internode length increased and then decreased. The longest leaves and internodes had the highest maximum growth rates. The size and maximum growth rates of putative preformed leaves were larger than putative neoformed leaves. As a shoot expanded, growth of one internode tended to cease during the linear phase of growth of its associated leaf and that of the succeeding internode.

Quantitative relationships for specific growth rates and macromolecular compositions of Mycobacterium tuberculosis, Streptomyces coelicolor A3(2) and Escherichia coli B/r: an integrative theoretical approach

Microbiology ◽  
2004 ◽  
Vol 150 (5) ◽  
pp. 1413-1426 ◽  
Author(s):  
Robert A. Cox
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Growth Rates ◽  
Specific Growth ◽  
Streptomyces Coelicolor ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
E Coli ◽  
Specific Growth Rates

Further understanding of the physiological states of Mycobacterium tuberculosis and other mycobacteria was sought through comparisons with the genomic properties and macromolecular compositions of Streptomyces coelicolor A3(2), grown at 30 °C, and Escherichia coli B/r, grown at 37 °C. A frame of reference was established based on quantitative relationships observed between specific growth rates (μ) of cells and their macromolecular compositions. The concept of a schematic cell based on transcription/translation coupling, average genes and average proteins was developed to provide an instantaneous view of macromolecular synthesis carried out by cells growing at their maximum rate. It was inferred that the ultra-fast growth of E. coli results from its ability to increase the average number of rRNA (rrn) operons per cell through polyploidy, thereby increasing its capacity for ribosome synthesis. The maximum growth rate of E. coli was deduced to be limited by the rate of uptake and consumption of nutrients providing energy. Three characteristic properties of S. coelicolor A3(2) growing optimally (μ=0·30 h−1) were identified. First, the rate of DNA replication was found to approach the rate reported for E. coli (μ=1·73 h−1); secondly, all rrn operons were calculated to be fully engaged in precursor-rRNA synthesis; thirdly, compared with E. coli, protein synthesis was found to depend on higher concentrations of ribosomes and lower concentrations of aminoacyl-tRNA and EF-Tu. An equation was derived for E. coli B/r relating μ to the number of rrn operons per genome. Values of μ=0·69 h−1 and μ=1·00 h−1 were obtained respectively for cells with one or two rrn operons per genome. Using the author's equation relating the number of rrn operons per genome to maximum growth rate, it is expected that M. tuberculosis with one rrn operon should be capable of growing much faster than it actually does. Therefore, it is suggested that the high number of insertion sequences in this species attenuates growth rate to still lower values.

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