scholarly journals Intraspecific competition controls spatial distribution and social organisation of the coral-dwelling goby Gobiodon histrio

2004 ◽  
Vol 278 ◽  
pp. 253-259 ◽  
Author(s):  
JPA Hobbs ◽  
PL Munday
Keyword(s):  
Spatial Distribution ◽  
Intraspecific Competition ◽  
Social Organisation

Spatial distribution and seed mass variation of Strophostyles helvola along Lake Erie

1996 ◽  
Vol 74 (8) ◽  
pp. 1313-1321 ◽  
Author(s):  
Mary Yanful ◽  
M. A. Maun
Keyword(s):  
Spatial Distribution ◽  
Intraspecific Competition ◽  
Lake Erie ◽  
Seed Mass ◽  
Field Studies ◽  
Sandy Beaches ◽  
Recurrent Event ◽  
Limiting Factor ◽  
Probability Of Survival ◽  
The Waves

Field studies were conducted to determine the survival, seed-mass variability, and reproductive strategies of wild bean, Strophostyles helvola (L.) Ell., plants on the foredunes at Port Burwell Provincial Park along Lake Erie. In spring, a large number of seedlings were found on the drift-line (area of beach where detritis deposits are cast on shore by the waves) and a small number both on the lakeward (mid-beach) and landward (high-beach) ends of the drift-line. Plants growing on the mid-beach were larger and produced a significantly greater number of heavier seeds than those on the drift-line. However, during late fall and winter months, a large proportion of these seeds were moved by wind and wave action to the drift-line. Intraspecific competition was not a limiting factor on the mid-beach; however, on the drift-line, the number of seeds per plant decreased significantly with an increase in density of plants from about 1 to 140/m2, suggesting that intraspecific competition may be an important limiting factor in seed production per plant. The mean mass per seed significantly declined over the growing season of S. helvola. There was a significant increase in mean seed mass with increasing pod size. Seeds in the centre of a pod were significantly heavier than those at the proximal and distal ends of a pod. Strophostyles helvola is able to flourish in the constantly shifting shoreline beach habitats along Lake Erie owing to two main factors. First, it is able to fully utilize the highly variable beach microhabitats and maintain high total reproductive output per square metre. Second, since burial in sand is a major recurrent event on sandy beaches, the high variability in seed mass will be of adaptive significance because seedlings from large seeds will not only be able to emerge from greater depths of burial in sand but also will have greater probability of survival under burial conditions. Keywords: seed mass, plant location, Strophostyles helvola, seed position, spatial distribution.

POPULATION MORTALITY AND CYCLICITY AS AFFECTED BY INTRASPECIFIC COMPETITION,

1977 ◽  
Vol 109 (6) ◽  
pp. 879-890 ◽  
Author(s):  
R. E. Stinner ◽  
J. W. Jones ◽  
C. Tuttle ◽  
R. E. Caron
Keyword(s):  
Probability Theory ◽  
Spatial Distribution ◽  
Intraspecific Competition ◽  
Heliothis Zea ◽  
Survival Rates ◽  
Basic Probability ◽  
Simulation Results ◽  
Population Mortality

AbstractA model for intraspecific competition that incorporates the effects of inter- and intra-stage survival rates, spatial distribution, and variation in growth is developed using basic probability theory. Simulation results for cannibalism in Heliothis zea (Boddie) are presented and intraspecific competition is shown to have effects on population cyclicity and on mortality.

scholarly journals Distribuição espacial de cupinzeiros epígeos de pastagem no município de Iporá-GO, Brasil

2011 ◽  
Vol 4 (2) ◽  
pp. 45-48 ◽  
Author(s):  
Hélida Ferreira da Cunha
Keyword(s):  
Spatial Distribution ◽  
Social Insects ◽  
Intraspecific Competition ◽  
Goodness Of Fit ◽  
Dispersion Pattern ◽  
Regular Pattern ◽  
Population Parameters ◽  
Termite Mounds ◽  
Chi Square ◽  
Made In

Cupins (Isoptera) são insetos sociais que vivem agrupados em cupinzeiros com elevada densidade, o que dificulta a estimativa de parâmetros populacionais, por isso, a abundância de cupins é feita pela contagem de ninhos. O objetivo foi estimar o padrão de distribuição espacial de cupinzeiros epígeos de Cornitermes sp. (Termitidae) de uma pastagem. O estudo foi feito em 1 hectare (ha) de pastagem de Brachiaria sp. em uma propriedade rural em Iporá-GO (16º44’ S e 51º11’ WO). A área foi subdividida em 25 parcelas de 400 m2 e o número de cupinzeiros por parcela foi contado. A distribuição espacial dos cupinzeiros foi estimada inicialmente pelo Índice de Dispersão (I) e pelo Índice de Agrupamento (k). Posteriormente, a frequência observada de cupinzeiros por parcela foi ajustada à distribuição de frequência apropriada ao padrão de dispersão e o grau de aderência foi testado pelo Qui-Quadrado (χ2). Um total de 196 cupinzeiros foi contado, que equivale a 0.02 ninhos por m2. Os índices de dispersão I=0,47 (χ2(24)= 11,40; P=0,99) e de agrupamento (k= -14,93) sugeriram um padrão uniforme. Mas, a distribuição espacial dos cupinzeiros na pastagem foi confirmada pela distribuição de aleatória de Poisson (χ2= 11,06 < χ2(8; α 0,05)= 15,51), conseqüência da ausência de competição intraespecífica. Conclui-se que a homogeneidade estrutural das pastagens é um tipo de ecossistema útil para o estudo de modelos ecológicos e que os cupins são grupos taxonômicos interessantes devido ao fato de que algumas espécies têm facilidade de colonizar ambientes em estágios iniciais de sucessão. Spatial Distribution of Epigean Termite Nests of the Pasture of the Iporá-GO, Brazil Abstract. Termites (Isoptera) are social insects that live in termite mounds grouped with a high density, making it difficult to estimate of the population parameters, therefore, the abundance of termites is calculate by counting the nests. The objective was to estimate the spatial distribution pattern of epigean termite nests of Cornitermes sp. (Termitidae) from a pasture. The study was made in 1 hectare (ha) of Brachiaria sp. pasture on a farm in Iporá-GO (16 º 44 'S and 51 º 11' WO). The area was subdivided into 25 plots of 400m2 and the termite nests per plot were counted. Initially, the spatial distribution of nests estimated by the Index of Dispersion (I) and by the Index of Clustering (k). Subsequently, the observed frequency of termite nests per plot was fit to the appropriate frequency distribution to dispersion pattern and goodness-of-fit was tested by Chi-Square (χ2). A total of 196 termite nests were counted, which equals to 0.02 nests per m2. The indexes of dispersion I=0.47 (χ2(24)= 11.40; P=0.99) and of clustering (k= -14.93) suggested a regular pattern. But the spatial distribution of the nests in the pasture was confirmed by random Poisson distribution (χ2= 11.06 < χ2(8; α 0.05)= 15.51), consequence of the absence of intraspecific competition. It is concluded that the structural homogeneity of pasture is a useful ecosystem for the study of ecological models and termites are interesting taxonomic group because some species are easy to colonize environments in early succession.

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.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

An analytical microscopic study of metals in fluidized catalytic cracking catalyst

1986 ◽  
Vol 44 ◽  
pp. 854-855
Author(s):  
Clifford S. Rainey
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Catalytic Cracking ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Acid Sites ◽  
Y Zeolite ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
High Regeneration

The spatial distribution of V and Ni deposited within fluidized catalytic cracking (FCC) catalyst is studied because these metals contribute to catalyst deactivation. Y zeolite in FCC microspheres are high SiO2 aluminosilicates with molecular-sized channels that contain a mixture of lanthanoids. They must withstand high regeneration temperatures and retain acid sites needed for cracking of hydrocarbons, a process essential for efficient gasoline production. Zeolite in combination with V to form vanadates, or less diffusion in the channels due to coke formation, may deactivate catalyst. Other factors such as metal "skins", microsphere sintering, and attrition may also be involved. SEM of FCC fracture surfaces, AEM of Y zeolite, and electron microscopy of this work are developed to better understand and minimize catalyst deactivation.

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