The searching behaviour of two species of phytoseiid mites, Phytoseiulus persimilis Athias-Henriot and Amblyseius degenerans (Berlese), in relation to the density and distribution of prey in an homogeneous area (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (4) ◽  
pp. 648-658 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Prey Capture ◽  
Phytoseiulus Persimilis ◽  
Absolute Magnitude ◽  
Phytoseiid Mites ◽  
Searching Behaviour ◽  
Different Types ◽  
Consistent Change ◽  
Homogeneous Area ◽  
The Absolute

Both Phytoseiulus persimilis and Amblyseius degenerans exhibited area-restricted searching after prey capture(s) regardless of the density and distribution of prey experienced. A reduction in searching speed and an increase in the absolute magnitude of turns following prey capture(s) contributed to area-restricted searching under all prey conditions with P. persimilis, whereas with A. degenerans, area-restricted searching was due to factors other than a consistent change in these searching parameters under all prey conditions. Phytoseiulus persimilis modified its overall searching behaviour to a greater extent at low than high prey densities and under clumped than uniform prey distributions, whereas A. degenerans showed similar postcapture behaviour under all prey conditions tested. The possible consequences of the behaviour of both predators on their searching success under different types of prey conditions are discussed.

scholarly journals Feature Image Watermarking Based on Bicubic Interpolation of Wavelet Coefficients Using CRT

2017 ◽  
Vol 11 (2) ◽  
pp. 93 ◽  
Author(s):  
Prajanto Wahyu Adi ◽  
Yani Parti Astuti ◽  
Egia Rosi Subhiyakto
Keyword(s):  
High Frequency ◽  
Image Watermarking ◽  
Absolute Magnitude ◽  
Wavelet Coefficients ◽  
Absolute Value ◽  
Average Value ◽  
Homogeneous Area ◽  
The Absolute ◽  
Bicubic Interpolation

The main objective of watermarking method is to improve the robustness and imperceptibility. This paper introduces an improved CRT watermarking method using absolute value of interpolated wavelet coefficients aiming to improve the imperceptibility and robustness. The standard CRT method embeds the watermark bits on the blocks of pixels evenly. Hence, it can significantly reduce the quality of watermarked images when the watermark lies on the homogeneous area. Otherwise, the proposed method is embedding the watermark bits on the heterogeneous area by sorting the absolute magnitude of wavelet coefficients descending. The waveletcoefficients are selected from high frequency wavelet sub band HH. This scheme is able to determine the appropriate embedding location in certain range of value. The watermark bits are then embedding on the selectedpixel value using CRT scheme. The result shows that the average imperceptibility value the CRT is 0.9980 while the proposed method has average value of 0.9993. On robustness against compression, the proposed method achieves better result compared to the CRT with the average NC values of 0.7916 higher than the CRT value of 0.7530. These prove that the proposed method has better performance in term of imperceptibility and robustness against compression than the CRT method.

Experimental studies on acarine predator–prey interactions: the numerical response of immature and adult predators (Acarina: Phytoseiidae)

1981 ◽  
Vol 59 (7) ◽  
pp. 1407-1418 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Prey Density ◽  
Survival Rates ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Phytoseiid Mites ◽  
Searching Behaviour ◽  
Predator Prey ◽  
Adult Females ◽  
History Of ◽  
Adult Lives

The numerical responses of two species of phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans, were studied in the laboratory. Developmental times and survival rates were examined in the immature instars and oviposition rates in adult females. Prey requirements for development, survival, and oviposition were lower with P. persimilis than A. degenerans due to the nature of their respective feeding and searching behaviour. The fecundity of P. persimilis increased linearly with increasing numbers of prey killed, whereas that of A. degenerans increased curvilinearly. Experiments on the effects of the feeding history of adult females on their fecundity showed that their response depended not only on their most recent nutritional history but also on prey conditions experienced early in their adult lives. The ability of the females to respond to an increase in prey density may be enhanced or reduced depending on the prey conditions experienced. The manner in which the requirements for prey, and the feeding and searching behaviour of the predators, influenced their responses is discussed.

Experimental studies on acarine predator–prey interactions: the response of predators to prey distribution in an homogeneous area (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (4) ◽  
pp. 639-647 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Functional Response ◽  
Prey Density ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Phytoseiid Mites ◽  
Predator Prey ◽  
Prey Distribution ◽  
Uniform Distributions ◽  
Homogeneous Area ◽  
Prey Depletion

A laboratory study was conducted to determine the effects of prey distribution in an homogeneous area on the searching success and functional response of two species of phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans. The results indicated that the spatial distribution of the prey affected the searching success and functional response of P. persimilis but not of A. degenerans. More prey were killed by the former predator when prey were clustered, followed by random and uniform distributions. In contrast to A. degenerans, the degree of prey aggregation at a given prey density also affected the number of prey killed by P. persimilis. With both predators, prey depletion affected the comparative success of the predators at certain prey distributions. It is concluded that P. persimilis is adapted to search for prey which aggregate, whereas A. degenerans is not. The results are discussed in terms of their potential importance in predation and biological control studies.

The feeding and searching behaviour of two species of phytoseiid mites, Phytoseiulus persimilis Athias-Henriot and Amblyseius degenerans (Berlese), at different prey densities (Acarina: Phytoseiidae)

1981 ◽  
Vol 59 (7) ◽  
pp. 1419-1430 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Prey Density ◽  
Phytoseiulus Persimilis ◽  
Phytoseiid Mites ◽  
Predatory Behaviour ◽  
Searching Behaviour ◽  
Lower Capacity

Detailed observations were made on various components of the predatory behaviour of each instar of two species of predacious phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans, in the laboratory. These observations revealed that many aspects of the feeding and searching behaviour of these predators are dependent on the prey density to which they are exposed. Differences between the two species are described and it is concluded that P. persimilis has a greater ability to modify its behaviour in relation to prey conditions than A. degenerans. The results explain why P. persimilis has a lower capacity for prey and lower prey requirements for survival, development, and reproduction than A. degenerans, and also the nature of the functional and numerical responses to prey density of the two species.

scholarly journals The Absolute Magnitude of the Early-Type MK Standards From Hipparcos Parallaxes

1998 ◽  
Vol 11 (1) ◽  
pp. 566-566
Author(s):  
C. Jaschek ◽  
A.E. Gómez
Keyword(s):  
Main Sequence ◽  
Rotational Velocity ◽  
Wide Band ◽  
Absolute Magnitude ◽  
Interstellar Extinction ◽  
Early Type ◽  
Class V ◽  
Luminosity Class ◽  
The Absolute ◽  
Absolute Magnitudes

We have analysed the standards of the MK system in the B0-F5 spectral region with the help of Hipparcos parallaxes, using only stars for which the error on the absolute magnitude is ≤ 0.3 mag. The sample stars (about one hundred) were scrutinized for companions and for interstellar extinction. We find that the main sequence is a wide band and that, although in general giants and dwarfs have different absolute magnitudes, the separation between luminosity class V and III is not clear. We conclude that there is no strict relation between luminosity class and absolute magnitude. The relation is only a statistical one and has a large intrinsic dispersion. We have analysed similarly the system of standards defined by Garrison and Gray (1994) separating low and high rotational velocity standards. We find similar effects as in the original MK system.

scholarly journals The Luminosity Determination

1995 ◽  
Vol 10 ◽  
pp. 399-402
Author(s):  
A.E. Gómez ◽  
C. Turon
Keyword(s):  
Main Sequence ◽  
Small Volume ◽  
Absolute Magnitude ◽  
Fitting Procedure ◽  
Trigonometric Parallaxes ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Kinematical Data ◽  
Magnitude Determination

The Hertzprung-Russel (HR) diagram luminosity calibration relies basically on three kinds of data: trigonometric parallaxes, kinematical data (proper motions and radial velocities) and cluster distances obtained by the zero-age main sequence fitting procedure. The most fundamental method to calculate the absolute magnitude is the use of trigonometric parallaxes, but up to now, accurate data only exist for stars contained in a small volume around the sun. Individual absolute magnitudes are obtained using trigonometric parallaxes or photometric and spectroscopic calibrations. In these calibrations the accuracy on the absolute magnitude determination ranges from ±0.m2 in the main sequence to ±0m5 in the giant branch. On the other hand, trigonometric parallaxes, kinematical data or cluster distances have been used to make statistical calibrations of the absolute magnitude. The standard error on the mean absolute magnitude calibrations ranges from ±0m3 to ±0m6 on the mean sequence, from ±0m5 to ±0m7 on thegiant branch and is of about 1mfor supergiants.Future improvements in the absolute magnitude determination will depend on the improvement of the basic data from the ground and space. A brief overview of the new available data is presented. In particular, the analysis of the first 30 months data of the Hipparcos mission (H30) (from the 37 months data of the whole mission) allows to perform a statistical evaluation of the improvements expected in the luminosity determination.

scholarly journals ON THE PROBLEM OF THE SPECIFIC FREQUENCY OF GLOBULAR CLUSTERS

2021 ◽  
pp. 137-142
Author(s):  
Ikram Uralbaevich Tadjibaev
Keyword(s):  
Observational Data ◽  
Globular Clusters ◽  
Spiral Galaxies ◽  
Empirical Relationship ◽  
Flux Ratio ◽  
Quadratic Function ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Specific Frequency ◽  
The Absolute

In the article, on the basis of observational data the problems of the specific frequency of globular clusters are studied. Possible relationships between them and the absolute stellar magnitude of their host galaxy are considered, where the observational data published in the literature were presented. It should be noted that before us the relationship between the specific frequency and the absolute magnitude is shown as exponential functions. An empirical relationship between the specific frequency and the absolute value of the host galaxy were obtained and showed that the dependence of the specific frequency on the absolute magnitude is not linear, but has a quadratic function. It is also shown that the specific frequency determines the number of globular clusters in a given galaxy relative to our Galaxy. Also in the article, based on the results of studies of the specific frequency, some discussions are presented related to the origin and evolution of globular clusters. The results obtained show that the ratios of the specific frequency to the luminosity of the host galaxy are different. Variations in the specific frequency of elliptical galaxies are associated with variations in the mass-to-luminous flux ratio. This may be due to the fact that the number of globular clusters in spiral galaxies per unit of luminosity of the halo and not of the entire galaxy. Analysis of the observational data shows that the values of the specific frequency of spiral galaxies are 5–6 times less than that of giant elliptical ones. As a result of the results of studies of the specific frequency of the globular clusters, unsolved problems are listed and possible solutions are shown. It is noted that the problem posed will be solved even more accurately if it is considered by the types of galaxies

scholarly journals The Parallaxes of U Gem Variables

1979 ◽  
Vol 53 ◽  
pp. 494-494
Author(s):  
Karl W. Kamper
Keyword(s):  
Confidence Level ◽  
Absolute Magnitude ◽  
Weighted Mean ◽  
Quiescent Phase ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

An Allegheny parallax series of SS Cyg, consisting of 52 exposures obtained on 15 nights, was recently measured on the PDS microphotometer at the David Dunlap Observatory, and a value of (m.e.) derived for the absolute parallax. This is close to the mean of the two previous discordant measures for this star given in the table below. The weighted mean of the three determinations implies that the absolute magnitude, at quiescent phase, of the star is between 7.0 and 9.0 formally at a 90% confidence level. Recent parallax determinations made at Lick by Vasilevskls et al. (1975) for three other stars, listed below along with the Mt. Wilson value for U Gem, imply even fainter absolute magnitudes.

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