scholarly journals Non-linear Relationships Between Density and Demographic Traits of Aedes

2021 ◽  
Author(s):  
Logan A. Sauers ◽  
Kelsey E. Hawes ◽  
Steven A. Juliano
Keyword(s):  
Population Growth ◽  
Empirical Relationship ◽  
Initial Density ◽  
Rate Of Change ◽  
Adult Size ◽  
Linear Relationships ◽  
Non Linear ◽  
Per Capita ◽  
Relationship Of ◽  
The Relationship

Abstract Understanding the relationship of population dynamics to density is central to many ecological investigations. Despite the importance of density-dependence in determining population growth, the empirical relationship between density and per capita growth remains understudied in most systems and is often assumed to be linear. In experimental studies of interspecific competition, investigators often evaluate the predicted outcomes by assuming such linear relationships, fitting linear functions, and estimating parameters of competition models. In this paper, we tested experimentally the shape of the relationship between estimated population rate of change and initial density using laboratory-reared populations of three mosquito species. We estimated per capita growth rate for these experimental populations over a thirty-fold range of larval densities at a standard resource abundance. We then compared fits of linear models and several different nonlinear models for the relationship of estimated rate of change and density. We find that that the relationship between density and per capita growth is strongly non-linear in all three mosquitoes. Components of population growth (survivorship, development time, adult size) are also nonlinearly related to initial density. The causes and consequences of this nonlinearity are likely to be important issues for population and community ecology.

Analysis of Maximum Expiratory Flow Volume Curves Using Canonical Correlation Analysis

1985 ◽  
Vol 24 (02) ◽  
pp. 91-100 ◽  
Author(s):  
W. van Pelt ◽  
Ph. H. Quanjer ◽  
M. E. Wise ◽  
E. van der Burg ◽  
R. van der Lende
Keyword(s):  
Correlation Analysis ◽  
Canonical Correlation Analysis ◽  
Canonical Correlation ◽  
Flow Volume ◽  
Non Linear ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Relationship Of ◽  
The Relationship ◽  
Age And Sex

SummaryAs part of a population study on chronic lung disease in the Netherlands, an investigation is made of the relationship of both age and sex with indices describing the maximum expiratory flow-volume (MEFV) curve. To determine the relationship, non-linear canonical correlation was used as realized in the computer program CANALS, a combination of ordinary canonical correlation analysis (CCA) and non-linear transformations of the variables. This method enhances the generality of the relationship to be found and has the advantage of showing the relative importance of categories or ranges within a variable with respect to that relationship. The above is exemplified by describing the relationship of age and sex with variables concerning respiratory symptoms and smoking habits. The analysis of age and sex with MEFV curve indices shows that non-linear canonical correlation analysis is an efficient tool in analysing size and shape of the MEFV curve and can be used to derive parameters concerning the whole curve.

Chloride Accumulation as a Homeostatic System: Negative Feedback Signals for Concentration and Turgor Maintenance Differ in a Glycophyte and a Halophyte

1980 ◽  
Vol 7 (3) ◽  
pp. 237 ◽  
Author(s):  
WJ Cram
Keyword(s):  
Negative Feedback ◽  
Turgor Maintenance ◽  
Non Linear ◽  
Steady Level ◽  
Homeostatic System ◽  
Chloride Accumulation ◽  
Relationship Of ◽  
The Relationship ◽  
Uptake Of Nutrients

Carrot tissue is taken as a representative glycophilic tissue. It accumulates K+, Cl- and total osmotica to a steady level after 10-15 days. This level of Cl- is nearly constant and is independent of external KCl concentration and of turgor. Cl- influx is also independent of turgor. It therefore appears that the Cl- accumulating system in carrot (and possibly in other glycophytes) can, under artificial conditions, act as a homeostat for intracellular C- concentration, and is not the basis of turgor maintenance. It is suggested that turgor might be maintained by controlled accumulation of K+ carboxylates in glycophytes. Beet tissue is taken as a representative halophilic tissue. It accumulates K+, Cl-, and total osmotica to a steady level after about 4 days. At this stage turgor is constant, due to differences in the levels of KCl accumulated. Cl- influx is stimulated by reducing turgor after a lag of 3-5 h. The relationship of Cl- influx to turgor is non-linear. It therefore appears that in beet (and possibly in other halophytes) turgor maintenance is based on the turgor-sensitive accumulation of Cl- salts. Cl- influx in beet is also affected by changes in intracellular Cl- concentration, as in carrot. It is suggested that this feedback relationship may primarily be part of a system for the controlled uptake of nutrients rather than of Cl- in both tissues.

scholarly journals Population Growth - The Social Development and Poverty Dimension

1999 ◽  
Vol 4 (1) ◽  
pp. 41-52
Author(s):  
M.S. Jillani
Keyword(s):  
Reproductive Health ◽  
Population Growth ◽  
Social Development ◽  
Human Health ◽  
Reproductive System ◽  
Social Wellbeing ◽  
The Social ◽  
The World ◽  
Relationship Of ◽  
The Relationship

The debate over the relationship of population and development is now more than 200 years old, starting with the treatise on population by Malthus, in 1798. The increase in population, ever since, has remained a matter of concern for economists and development planners. The most recent high point of the issue was witnessed at Cairo in September, 1994. The conference which was attended by more than 10,000 persons from all over the world ended with an agreement on the issues involved in the growth of population and the economy. The outcome was a Plan of Action for the next twenty years, which would concentrate on Reproductive Health in order to obtain, “a state of complete physical, mental and social wellbeing, and not merely the absence of disease or infirmity in all matters relating to the reproductive system and its functions and process”. This can be a turn-around in global efforts for human health and welfare, if properly implemented.

An improvement to the ANN-enhanced flow rating method

2021 ◽  
Author(s):  
Bernhard Schmid
Keyword(s):  
Neural Network ◽  
Electrical Conductivity ◽  
Water Resources ◽  
Flow Rate ◽  
Major Ions ◽  
Rate Of Change ◽  
Data Set ◽  
Input Variables ◽  
Relationship Of ◽  
The Relationship

<p>The work reported here builds upon a previous pilot study by the author on ANN-enhanced flow rating (Schmid, 2020), which explored the use of electrical conductivity (EC) in addition to stage to obtain ‘better’, i.e. more accurate and robust, estimates of streamflow. The inclusion of EC has an advantage, when the relationship of EC versus flow rate is not chemostatic in character. In the majority of cases, EC is, indeed, not chemostatic, but tends to decrease with increasing discharge (so-called dilution behaviour), as reported by e.g. Moatar et al. (2017), Weijs et al. (2013) and Tunqui Neira et al.(2020). This is also in line with this author’s experience.</p><p>The research presented here takes the neural network based approach one major step further and incorporates the temporal rate of change in stage and the direction of change in EC among the input variables (which, thus, comprise stage, EC, change in stage and direction of change in EC). Consequently, there are now 4 input variables in total employed as predictors of flow rate. Information on the temporal changes in both flow rate and EC helps the Artificial Neural Network (ANN) characterize hysteretic behaviour, with EC assuming different values for falling and rising flow rate, respectively, as described, for instance, by Singley et al. (2017).</p><p>The ANN employed is of the Multilayer Perceptron (MLP) type, with stage, EC, change in stage and direction of change in EC of the Mödling data set (Schmid, 2020) as input variables. Summarising the stream characteristics, the Mödling brook can be described as a small Austrian stream with a catchment of fairly mixed composition (forests, agricultural and urbanized areas). The relationship of EC versus flow reflects dilution behaviour. Neural network configuration 4-5-1 (the 4 input variables mentioned above, 5 hidden nodes and discharge as the single output) with learning rate 0.05 and momentum 0.15 was found to perform best, with testing average RMSE (root mean square error) of the scaled output after 100,000 epochs amounting to 0.0138 as compared to 0.0216 for the (best performing) 2-5-1 MLP with stage and EC as inputs only.    </p><p> </p><p>References</p><p>Moatar, F., Abbott, B.W., Minaudo, C., Curie, F. and Pinay, G.: Elemental properties, hydrology, and biology interact to shape concentration-discharge curves for carbon, nutrients, sediment and major ions. Water Resources Res., 53, 1270-1287, 2017.</p><p>Schmid, B.H.: Enhanced flow rating using neural networks with water stage and electrical conductivity as predictors. EGU2020-1804, EGU General Assembly 2020.</p><p>Singley, J.G., Wlostowski, A.N., Bergstrom, A.J., Sokol, E.R., Torrens, C.L., Jaros, C., Wilson, C.,E., Hendrickson, P.J. and Gooseff, M.N.: Characterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales. Water Resources Res. 53, 4124-4141, 2017.</p><p>Tunqui Neira, J.M., Andréassian, V., Tallec, G. and Mouchel, J.-M.: A two-sided affine power scaling relationship to represent the concentration-discharge relationship. Hydrol. Earth Syst. Sci. 24, 1823-1830, 2020.</p><p>Weijs, S.V., Mutzner, R. and Parlange, M.B.: Could electrical conductivity replace water level in rating curves for alpine streams? Water Resources Research 49, 343-351, 2013.</p>

scholarly journals Interhemispheric comparison of average substorm onset locations: evidence for deviation from conjugacy

2007 ◽  
Vol 25 (4) ◽  
pp. 989-999 ◽  
Author(s):  
H. Wang ◽  
H. Lühr ◽  
S. Y. Ma ◽  
H. U. Frey
Keyword(s):  
Magnetic Field ◽  
Significant Influence ◽  
Solar Zenith Angle ◽  
Statistical Study ◽  
Substorm Onset ◽  
Seasonal Effects ◽  
Linear Relationships ◽  
Substorm Onsets ◽  
Relationship Of ◽  
The Relationship

Abstract. Based on 2760 well-defined substorm onsets in the Northern Hemisphere and 1432 in the Southern Hemisphere observed by the FUV Imager on board the IMAGE spacecraft, a detailed statistical study is performed including both auroral regions. This study focuses on the hemispheric comparisons. Southward pointing interplanetary magnetic field (IMF) is favorable for substorm to occur, but still 30% of the events are preceded by northward IMF. The magnetic latitude (MLat) of substorm onset depends mainly on the merging electric field (Em) with a relationship of |dMLat|= −5.2 Em0.5, where dMLat is the deviation from onset MLat. In addition, seasonal effects on onset MLat are also detected, with about 2 degrees higher latitudes during solstices than equinoxes. Both IMF By and solar illumination have a significant influence on the magnetic local time (MLT) of onsets. An average relation, dMLT=0.25 By between IMF By and the deviation from onset MLT, was found. The By dependence varies slightly with the onset latitude. At lower latitudes (higher activity) it is reduced. After removal of the relationship with IMF By a linear relationships remains between the solar zenith angle and onset MLT with dMLT=1 min/deg. Therefore, both solar illumination and IMF By can contribute to hemispheric longitudinal displacements of substorm onset locations from conjugacy. No indications for systematic latitudinal displacements between the hemispheres have been found.

Survival, Fecundity, and Population Growth of Melanoplus bilituratus (Wlk.) (Orthoptera: Acrididae) in Relation to Date of Hatching

1960 ◽  
Vol 92 (1) ◽  
pp. 1-10 ◽  
Author(s):  
R. Pickford
Keyword(s):  
General Population ◽  
Population Growth ◽  
Western Canada ◽  
Adverse Weather ◽  
Relationship Of ◽  
The Relationship

In Western Canada, Melanoplus bilituratus (Wlk.) may hatch from early May to mid-July, depending on seasonal conditions. Little information is available on the relationship of time of hatching to population growth except that grasshoppers emerging too early in the spring may be destroyed by adverse weather that often occurs at this time (Shotwell, 1941). Also, it has beenassumed that grasshoppers hatching late in the summer mature too late to contribute much to general population growth.

Water Conservancy and Hydropower Engineering Construction System Brittleness Evaluation Based on Choquest Integral

2012 ◽  
Vol 459 ◽  
pp. 638-643
Author(s):  
Lei Zhang ◽  
Zi Yang Li
Keyword(s):  
Evaluation Model ◽  
Cumulative Effect ◽  
Engineering Construction ◽  
Non Linear ◽  
Cumulative Function ◽  
Water Conservancy ◽  
Hydropower Engineering ◽  
Relationship Of ◽  
The Relationship ◽  
Construction System

Water conservancy and hydropower engineering construction system is a typical multi-level complex system and its swarm identity is apparent to brittleness cumulative effect. The brittle sources are interlinked and associated, thus there are topological forms of different brittle sources, which make the relationship of brittleness evaluation cumulative function to be non-linear. In traditional evaluation methods, indicators are usually assumed to be independent, which does not satisfy the non-linear characteristics of water conservancy and hydropower engineering construction system brittleness. Thus, in this paper, weak monotonic of fuzzy measure is used to replace the addition function, brittleness evaluation model of water conservancy and hydropower engineering construction system based on Choquest integral is built.

Impact of Plant Spacing and Population on Yield for Single-Row Nonirrigated Peanuts (Arachis hypogaea L.)

2000 ◽  
Vol 27 (2) ◽  
pp. 52-56 ◽  
Author(s):  
D. A. Sternitzke ◽  
M. C. Lamb ◽  
J. I. Davidson ◽  
R. T. Barron ◽  
C. T. Bennet
Keyword(s):  
Field Experiments ◽  
Rate Of Change ◽  
Plant Spacing ◽  
Lower Yield ◽  
Arachis Hypogaea L ◽  
Average Plant ◽  
Relationship Of ◽  
The Relationship ◽  
Water Nutrients ◽  
Lower Population

Abstract Poor peanut emergence often results in lower yield and loss of revenue. Farmers attempting to recapture lost income sometimes lose even more by replanting because replant costs may exceed the benefits of added yield. The purpose of this study was to develop an empirical equation to predict peanut yield based on total emergence 21 d after planting and an estimate of yield for a full stand of peanuts. Field experiments were conducted in Terrell Co., Georgia during 1997 and 1998 for nonirrigated peanut (cv. Georgia Green) grown in an Americus sand (thermic Rhodic Paleudults). To mimic poor emergence and concomitant random plant spacing, rows within plots were thinned at random locations to attain populations of 4.4, 3.3, 2.6, 2.1, and 1.6 plants/m-row. Control plots were not thinned and total emergence was approximately 12.7 plants/m-row. As total emergence and population decreased, yield also decreased whereas pod mass per plant increased. This increase was likely attributed to a reduction in competition from adjacent peanut plants for water, nutrients, and light. Higher population treatments had smaller pod mass/plant and greater overall yield than lower population treatments with higher pod mass/plant. Random plant-to-plant spacing associated with poor emergence was used to predict pod mass/plant as a function of average plant spacing. Results from this research established models defining the relationship of the rate of change of pod mass per plant with average plant spacing and provided a new method of predicting yield in the event of poor emergence.

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