scholarly journals An explicit formula for a dispersal kernel in a patchy landscape

2019 ◽  
Author(s):  
Ali Beykzadeh ◽  
James Watmough
Keyword(s):  
Population Density ◽  
Continuous Space ◽  
Heterogeneous Landscape ◽  
Classical Work ◽  
Special Cases ◽  
Dispersal Stage ◽  
Patchy Landscape ◽  
Patch Boundary ◽  
Two Stages ◽  
Reproduction Stage

AbstractIntegrodifference equations (IDEs) are often used for discrete-time continuous-space models in mathematical biology. The model includes two stages: the reproduction stage, and the dispersal stage. The output of the model is the population density of a species for the next generation across the landscape, given the current population density. Most previous models for dispersal in a heterogeneous landscape approximate the landscape by a set of homogeneous patches, and allow for different demographic and dispersal rates within each patch. Some work has been done designing and analyzing models which also include a patch preference at the boundaries, which is commonly referred to as the degree of bias. Individuals dispersing across a patchy landscape can detect the changes in habitat at a neighborhood of a patch boundary, and as a result, they might change the direction of their movement if they are approaching a bad patch.In our work, we derive a generalization of the classic Laplace kernel, which includes different dispersal rates in each patch as well as different degrees of bias at the patch boundaries. The simple Laplace kernel and the truncated Laplace kernel most often used in classical work appear as special cases of this general kernel. The form of this general kernel is the sum of two different terms: the classic truncated Laplace kernel within each patch, and a correction accounting for the bias at patch boundaries.

scholarly journals Effects of Water Table, Population Density and Transplanting Time on Vegetative Growth of Black Sticky Rice at Floating Seedbed Method

2020 ◽  
Vol 9 (2) ◽  
pp. 167-174
Author(s):  
Rofiqoh Purnama Ria ◽  
Benyamin Lakitan ◽  
Zaidan P. Negara
Keyword(s):  
Population Density ◽  
Factorial Design ◽  
Water Table ◽  
Vegetative Growth ◽  
Root Length ◽  
Leaf Length ◽  
Seedling Density ◽  
Second Stage ◽  
Two Stages ◽  
Plot Design

Ria RP, Lakitan B, Negara ZP. 2020. Effects of water table, seedling density and transplanting time on vegetative growth of black sticky rice at floating seedbed. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands  9(2): 167-174.Study on black sticky rice cultivation in South Sumatera is seldom carry out. The objective of this study was to evaluate the effect of water table and population density on the growth of rice during seedling preparation at floating seedbed; furthermore, this study aimed to evaluate the effect of transplanting time on vegetative growth of black sticky rice. The research was started in May 2018 in Palembang. Black sticky variety used in this research was Toraja variety. The raft used is made from 1,5 l plastic bottles which are arranged to reach  2x1 meters in size. This study was conducted by two stages. The first stage was for water table and population density treatments laid on split plot design. The second stage was for transplanting time utilizing completely randomized factorial design. Statistically, results showed water table and population density significantly influensced root length of black sticky rice and transplanting time 14 DAS haad an effect on the leaf length , leaf width and leaf area.

Inference on binary images from binary data

1996 ◽  
Vol 28 (3) ◽  
pp. 627-640 ◽  
Author(s):  
C. A. Glasbey
Keyword(s):  
Binary Data ◽  
Binary Image ◽  
Lattice Points ◽  
Rounding Error ◽  
Electron Micrograph ◽  
Continuous Space ◽  
Binary Images ◽  
Two Stages

The problem addressed is to reverse the degradation which occurs when images are digitised: they are blurred, subjected to noise and rounding error, and sampled only at a lattice of points. Inference is considered for the fundamental case of binary scenes, binary data and isotropic blur. The inferential process is separable into two stages: first from the lattice points to a binary image in continuous space and then the reversal of thresholding and blur. Methods are motivated by, and illustrated using, an electron micrograph of an immunogold-labelled section of tulip virus.

scholarly journals Modified Optimal Class of Newton-Like Fourth-Order Methods for Multiple Roots

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 526 ◽  
Author(s):  
Munish Kansal ◽  
Ramandeep Behl ◽  
Mohammed Ali A. Mahnashi ◽  
Fouad Othman Mallawi
Keyword(s):  
Fourth Order ◽  
Numerical Experiments ◽  
Chemical Reactor ◽  
Multiple Roots ◽  
Continuous Stirred Tank Reactor ◽  
Fractional Conversion ◽  
Special Cases ◽  
Continuous Stirred Tank ◽  
Two Stages ◽  
Good Number

Here, we propose optimal fourth-order iterative methods for approximating multiple zeros of univariate functions. The proposed family is composed of two stages and requires 3 functional values at each iteration. We also suggest an extensive convergence analysis that demonstrated the establishment of fourth-order convergence of the developed methods. It is interesting to note that some existing schemes are found to be the special cases of our proposed scheme. Numerical experiments have been performed on a good number of problems arising from different disciplines such as the fractional conversion problem of a chemical reactor, continuous stirred tank reactor problem, and Planck’s radiation law problem. Computational results demonstrates that suggested methods are better and efficient than their existing counterparts.

Inference on binary images from binary data

1996 ◽  
Vol 28 (03) ◽  
pp. 627-640
Author(s):  
C. A. Glasbey
Keyword(s):  
Binary Data ◽  
Binary Image ◽  
Lattice Points ◽  
Rounding Error ◽  
Electron Micrograph ◽  
Continuous Space ◽  
Binary Images ◽  
Two Stages

The problem addressed is to reverse the degradation which occurs when images are digitised: they are blurred, subjected to noise and rounding error, and sampled only at a lattice of points. Inference is considered for the fundamental case of binary scenes, binary data and isotropic blur. The inferential process is separable into two stages: first from the lattice points to a binary image in continuous space and then the reversal of thresholding and blur. Methods are motivated by, and illustrated using, an electron micrograph of an immunogold-labelled section of tulip virus.

A basis for predictive modelling of the relationship of potato yields to population density of the potato cyst nematode, Globodera pallida

1998 ◽  
Vol 130 (1) ◽  
pp. 45-51 ◽  
Author(s):  
M. S. PHILLIPS ◽  
D. L. TRUDGILL ◽  
C. A. HACKETT ◽  
M. HANCOCK ◽  
J. M. HOLLIDAY ◽  
...  
Keyword(s):  
Population Density ◽  
Yield Loss ◽  
Predictive Modelling ◽  
Globodera Pallida ◽  
Nematode Population ◽  
Initial Population ◽  
Initial Population Density ◽  
Potato Yields ◽  
Two Stages ◽  
The Relationship

The relationship between initial population density of Globodera pallida and yield was examined for five genotypes of potato at four different experimental sites; two in Scotland and two in England. The experiments at each site were conducted in two stages. The experimental area was first manipulated using resistant and susceptible potato cultivars to give plots with different nematode population densities to act as the initial populations (Pi) for the second stage. The main experiment was conducted using a range of host genotypes that differed in their tolerance and susceptibility. The utility of an inverse linear model relating yield to initial population density was confirmed as were differences in cultivar tolerance. Site differences in yield loss were also observed. It was found that the model could be modified to include the partitioning of genotype and site effects. The implications of this in terms of developing further models to predict yield loss and nematode population dynamics are discussed.

Urban Residential Analysis: 2. Spatial Consumer Equilibrium

1976 ◽  
Vol 8 (5) ◽  
pp. 489-506 ◽  
Author(s):  
G J Papageorgiou ◽  
H Mullally
Keyword(s):  
Urban Form ◽  
Continuous Distribution ◽  
Land Value ◽  
Spatial Equilibrium ◽  
Land Use Patterns ◽  
Continuous Space ◽  
Urban Structures ◽  
Special Cases ◽  
Residential Land Use ◽  
Additional Assumptions

Part 1 of this two-part series was concerned with the description and analysis of elements that transcend diverse urban structures of the ‘service’ type. The conclusions were general and abstract. Beyond this unified realm a more detailed description of urban form requires additional assumptions. The nature of such assumptions defines urban form within the confines of positive or normative analysis. Here the additional assumptions define spatial equilibrium within an ‘open’ city. Special cases of such equilibria have been studied extensively. In contrast part 2 develops the general case of a multicentre multiincome city. The properties of spatial-equilibrium bid-rent functions, their synthesis to a composite land-value surface, as well as the properties of this composite, are analyzed in section 1. The next section examines residential land-use patterns generated in a ‘service’ city. Such patterns turn out to be dramatically different from those of other urban types. Section 3 discusses the complex land-value and density surfaces that unfold over the landscape. Finally, section 4 provides what is probably the only analytically solved example of a spatial-equilibrium model related to a hierarchy of centres and to a continuous distribution of incomes over a continuous space.

Electron Beam Damage of Biomolecules Assessed by Energy Loss Spectroscopy

1978 ◽  
Vol 36 (3) ◽  
pp. 61-69
Author(s):  
M. Isaacson ◽  
M.L. Collins ◽  
M. Listvan
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Structural Integrity ◽  
Analytical Electron Microscopy ◽  
High Dose ◽  
Dose Rates ◽  
Special Cases ◽  
Analytical Electron ◽  
Atom Migration ◽  
Beam Damage

Over the past five years it has become evident that radiation damage provides the fundamental limit to the study of blomolecular structure by electron microscopy. In some special cases structural determinations at very low doses can be achieved through superposition techniques to study periodic (Unwin & Henderson, 1975) and nonperiodic (Saxton & Frank, 1977) specimens. In addition, protection methods such as glucose embedding (Unwin & Henderson, 1975) and maintenance of specimen hydration at low temperatures (Taylor & Glaeser, 1976) have also shown promise. Despite these successes, the basic nature of radiation damage in the electron microscope is far from clear. In general we cannot predict exactly how different structures will behave during electron Irradiation at high dose rates. Moreover, with the rapid rise of analytical electron microscopy over the last few years, nvicroscopists are becoming concerned with questions of compositional as well as structural integrity. It is important to measure changes in elemental composition arising from atom migration in or loss from the specimen as a result of electron bombardment.

Altered Fine Structure of B Lymphocytes Correlated with Defective Terminal Differentiation

1973 ◽  
Vol 31 ◽  
pp. 386-387
Author(s):  
Dale E. Bockman ◽  
L. Y. Frank Wu ◽  
Alexander R. Lawton ◽  
Max D. Cooper
Keyword(s):  
Immune Deficiency ◽  
B Lymphocytes ◽  
Plasma Cells ◽  
Present Report ◽  
Specific Antigen ◽  
Terminal Differentiation ◽  
Second Stage ◽  
Two Stages ◽  
Deficiency Diseases ◽  
Cell Line Generation

B-lymphocytes normally synthesize small amounts of immunoglobulin, some of which is incorporated into the cell membrane where it serves as receptor of antigen. These cells, on contact with specific antigen, proliferate and differentiate to plasma cells which synthesize and secrete large quantities of immunoglobulin. The two stages of differentiation of this cell line (generation of B-lymphocytes and antigen-driven maturation to plasma cells) are clearly separable during ontogeny and in some immune deficiency diseases. The present report describes morphologic aberrations of B-lymphocytes in two diseases in which second stage differentiation is defective.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

Decoration technique and surface physics

1978 ◽  
Vol 36 (1) ◽  
pp. 436-437 ◽  
Author(s):  
H. Bethge
Keyword(s):  
Diffusion Path ◽  
Special Importance ◽  
Surface Physics ◽  
Step Structure ◽  
Initial Stage ◽  
Special Cases ◽  
Atomic Surface ◽  
The Mean ◽  
Bulk Structure ◽  
Decoration Technique

Besides the atomic surface structure, diverging in special cases with respect to the bulk structure, the real structure of a surface Is determined by the step structure. Using the decoration technique /1/ it is possible to image step structures having step heights down to a single lattice plane distance electron-microscopically. For a number of problems the knowledge of the monatomic step structures is important, because numerous problems of surface physics are directly connected with processes taking place at these steps, e.g. crystal growth or evaporation, sorption and nucleatlon as initial stage of overgrowth of thin films.To demonstrate the decoration technique by means of evaporation of heavy metals Fig. 1 from our former investigations shows the monatomic step structure of an evaporated NaCI crystal. of special Importance Is the detection of the movement of steps during the growth or evaporation of a crystal. From the velocity of a step fundamental quantities for the molecular processes can be determined, e.g. the mean free diffusion path of molecules.

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