Bivariate normal song territories in ovenbirds

1978 ◽  
Vol 56 (10) ◽  
pp. 2088-2092 ◽  
Author(s):  
Reto Zach ◽  
J. Bruce Falls
Keyword(s):  
Spatial Distribution ◽  
Environmental Heterogeneity ◽  
Equal Frequency ◽  
Bivariate Normal ◽  
Fixed Boundaries

Song perches of each of nine male ovenbirds were bivariate normal in spatial distribution. Thus, song territories had no fixed boundaries. Song territories were elliptical rather than circular in shape, presumably due to environmental heterogeneity. Eighty-five percent equal frequency ellipses, which contain about 85% of the song perches of a given bird, corresponded approximately in area to the more conventional 95% song territory. Similarly, 90% equal frequency ellipses had about the same area as total song territories. However, all area estimates yielded closely correlated results. Distances between song centers and nest locations were highly variable. The distribution of nests was similar to that of song perches.

scholarly journals Dwarf-shrubs dynamics in Mediterranean high mountain ecosystems

2021 ◽  
Author(s):  
Andrea De Toma ◽  
Marta Carboni ◽  
Manuele Bazzichetto ◽  
Marco Malavasi ◽  
Maurizio Cutini
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Environmental Factors ◽  
Environmental Heterogeneity ◽  
Temporal Trends ◽  
Shrub Encroachment ◽  
High Mountain ◽  
Fine Scale ◽  
Dwarf Shrubs ◽  
The Past

AbstractQuestionVegetation in the alpine and treeline ecotone faces changes in both climate and land use. Shrub encroachment is considered an effect of these changes, but it’s still unclear how this effect is mediated by environmental heterogeneity. Our goal is to determine which environmental factors shape the fine-scale spatial distribution and temporal trends of alpine dwarf shrub.LocationThree sites in the Central Apennine, Italy.MethodsWe used a comprehensive set of environmental factors across a broad temporal span to model, at a fine-scale, both (1) the current spatial distribution and (2) the change in shrub cover over the past 60 years.ResultsOur results show that dwarf shrubs have generally increased in our study sites over the past 60 years, yet their distribution is strongly shaped by the joint influence of the fine-scale topography, productivity, land use and micro-climate. In particular, shrubs have been locally favored in areas with harsher alpine environmental constraints and stronger resource limitation. Instead, contrary to expectations, at this fine scale, warmer temperatures and the decline in grazing have not favored shrub encroachment.ConclusionDwarf shrubs appear as a stress-tolerant, pioneer vegetation that is currently distributed mainly over areas that are otherwise sparsely vegetated. It appears that shrubs exhibit poor competitive ability to invade grasslands and, though they have increased overall, they remain restricted to the least productive areas. Fine-scale environmental heterogeneity may strongly influence future responses of dwarf shrubs in changing alpine ecosystems.

scholarly journals The ecology of heterogeneity: soil bacterial communities and C dynamics

2021 ◽  
Author(s):  
Xavier Raynaud ◽  
Hannes Schmidt ◽  
Naoise Nunan
Keyword(s):  
Spatial Distribution ◽  
Microbial Ecology ◽  
Environmental Heterogeneity ◽  
Fundamental Property ◽  
Molecular Heterogeneity ◽  
Spatially Explicit Model ◽  
Fully Integrated ◽  
Soil Bacterial Communities ◽  
Decomposition Of Organic Matter ◽  
Bacterial Decomposition

<p>Heterogeneity is a fundamental property of soil that is often overlooked in microbial ecology. Although it is generally accepted that the heterogeneity of soil underpins the emergence and maintenance of microbial diversity, the profound and far-reaching consequences that heterogeneity can have on many aspects of microbial ecology and activity have yet to be fully apprehended and have not been fully integrated into our understanding of microbial functioning.</p><p>Heterogeneity in soils has multiple facets, from the molecular heterogeneity of the diversity of substrate available, the activity heterogeneity due to the activity of microbial species and the spatial heterogeneity of the soil structure and the distribution of organisms.</p><p>In this contribution we present a simple, spatially explicit model that can be used to understand how the interactions between the heterogeneity of decomposers (in terms of species and spatial distribution) and environmental heterogeneity (in terms of the diversity of substrates and their spatial distribution) affect the bacterial decomposition of organic matter. We found that environmental heterogeneity is a key element in determining the variability of the decomposition process.</p>

A MATHEMATICAL MODEL FOR SPATIALLY EXPANDING INFECTED AREA OF EPIDEMICS TRANSMITTED THROUGH HETEROGENEOUSLY DISTRIBUTED SUSCEPTIBLE UNITS

2005 ◽  
Vol 13 (02) ◽  
pp. 151-171 ◽  
Author(s):  
SHINKO KOSHIBA ◽  
HIROMI SENO
Keyword(s):  
Mathematical Model ◽  
Stochastic Process ◽  
Spatial Distribution ◽  
Fractal Dimension ◽  
Environmental Heterogeneity ◽  
Spatial Expansion ◽  
Fractal Nature ◽  
Modeling Analysis ◽  
Infected Area ◽  
The Moment

Little is known about the effect of environmental heterogeneity on the spatial expansion of epidemics. In this work, to focus on the question of how the extent of epidemic damage depends on the spatial distribution of susceptible units, we develop a mathematical model with a simple stochastic process, and analyze it. We assume that the unit of infection is immobile, as town, plant, etc. and classify the units into three classes: susceptible, infective and recovered. We consider the range expanded by infected units, the infected rangeR, assuming a certain generalized relation between R and the total number of infected units k, making use of an index, a sort of fractal dimension, to characterize the spatial distribution of infected units. From the results of our modeling analysis, we show that the expected velocity of spatial expansion of infected range is significantly affected by the fractal nature of spatial distribution of immobile susceptible units, and is temporally variable. When the infection finally terminates at a moment, the infected range at the moment is closely related to the nature of spatial distribution of immobile susceptible units, which is explicitly demonstrated in our analysis.

Effects of riffle length on the short-term movement of fishes among stream pools

2000 ◽  
Vol 57 (7) ◽  
pp. 1508-1514 ◽  
Author(s):  
D G Lonzarich ◽  
M R Lonzarich ◽  
M L Warren Jr.
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Spatial Variability ◽  
Fish Populations ◽  
Fish Movement ◽  
Equal Frequency ◽  
Short Term ◽  
Fish Conservation ◽  
Habitat Dynamics ◽  
Resource Conditions

Recent research has suggested that the within-habitat dynamics of fish populations and assemblages can be affected by the spatial distribution of habitats within streams. In this study, we determined the extent to which pool isolation (length of riffles connecting adjacent pools) influenced fish movement in two Arkansas streams. We marked individuals from 12 pools assigned to two treatment categories: pools separated by long riffles (>50 m) and those separated by short riffles (<10 m). Repeatedly snorkeling pools for 3 days in 1995 and 1997, we discovered substantial emigration (>20%) and significant effects of riffle length. Total emigration from short-riffle pools was three times higher (29%) than movement from long-riffle pools (10%). Further, marked fish in short-riffle pools moved upstream and downstream with equal frequency, whereas fish in long-riffle pools moved twice as often downstream. Collectively, these results indicate significant effects of habitat spacing on short-term movement patterns by fish. In streams, where fish are distributed within a mosaic of habitats of varying quality, such movements may allow individuals to assess spatial variability in resource conditions (e.g., food, predators). Because land-use activities can alter habitat spacing, these findings have important implications for fish conservation in degraded streams.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

SEM evaluation of the TEM cold-stage double-film specimen

1984 ◽  
Vol 42 ◽  
pp. 272-273
Author(s):  
Jayesh Bellare
Keyword(s):  
Spatial Distribution ◽  
Sample Preparation ◽  
Sample Thickness ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Liquid Sample ◽  
Thin Specimen ◽  
Sample Preparation Technique ◽  
Cold Stage ◽  
Film Specimen

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

Ultrastructural analysis of the spatial distribution of MRNA

1992 ◽  
Vol 50 (1) ◽  
pp. 552-553
Author(s):  
Gary Bassell ◽  
Robert H. Singer
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
In Situ Hybridization ◽  
High Resolution ◽  
Nucleic Acids ◽  
Colloidal Gold ◽  
Dna Probe ◽  
Nucleotide Analogs ◽  
Gold Particles

We have been investigating the spatial distribution of nucleic acids intracellularly using in situ hybridization. The use of non-isotopic nucleotide analogs incorporated into the DNA probe allows the detection of the probe at its site of hybridization within the cell. This approach therefore is compatible with the high resolution available by electron microscopy. Biotinated or digoxigenated probe can be detected by antibodies conjugated to colloidal gold. Because mRNA serves as a template for the probe fragments, the colloidal gold particles are detected as arrays which allow it to be unequivocally distinguished from background.

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