scholarly journals Substrate growth dynamics and biomineralization of an Ediacaran encrusting poriferan

2018 ◽  
Vol 285 (1870) ◽  
pp. 20171938 ◽  
Author(s):  
Rachel Wood ◽  
Amelia Penny
Keyword(s):  
Internal Structure ◽  
Growth Form ◽  
Growth Dynamics ◽  
Skeletal Growth ◽  
Partial Mortality ◽  
Total Group ◽  
Large Size ◽  
Rapid Formation ◽  
Substrate Competition ◽  
Growth Banding

The ability to encrust in order to secure and maintain growth on a substrate is a key competitive innovation in benthic metazoans. Here we describe the substrate growth dynamics, mode of biomineralization and possible affinity of Namapoikia rietoogensis , a large (up to 1 m), robustly skeletal, and modular Ediacaran metazoan which encrusted the walls of synsedimentary fissures within microbial–metazoan reefs. Namapoikia formed laminar or domal morphologies with an internal structure of open tubules and transverse elements, and had a very plastic, non-deterministic growth form which could encrust both fully lithified surfaces as well as living microbial substrates, the latter via modified skeletal holdfasts. Namapoikia shows complex growth interactions and substrate competition with contemporary living microbialites and thrombolites, including the production of plate-like dissepiments in response to microbial overgrowth which served to elevate soft tissue above the microbial surface. Namapoikia could also recover from partial mortality due to microbial fouling. We infer initial skeletal growth to have propagated via the rapid formation of an organic scaffold via a basal pinacoderm prior to calcification. This is likely an ancient mode of biomineralization with similarities to the living calcified demosponge Vaceletia. Namapoikia also shows inferred skeletal growth banding which, combined with its large size, implies notable individual longevity. In sum, Namapoikia was a large, relatively long-lived Ediacaran clonal skeletal metazoan that propagated via an organic scaffold prior to calcification, enabling rapid, effective and dynamic substrate occupation and competition in cryptic reef settings. The open tubular internal structure, highly flexible, non-deterministic skeletal organization, and inferred style of biomineralization of Namapoikia places probable affinity within total-group poriferans.

scholarly journals Internal Structure of Large Size Vacuum-Cast Ingots

1961 ◽  
Vol 1 (3) ◽  
pp. 31-39
Author(s):  
Shinsaku Onodera ◽  
Yoshitaka Nakagawa ◽  
Noboru Hiraoka
Keyword(s):  
Internal Structure ◽  
Large Size

scholarly journals Towards the analysis of coral skeletal density-banding using deep learning

2022 ◽  
Vol 4 (2) ◽  
Author(s):  
Ainsley Rutterford ◽  
Leonardo Bertini ◽  
Erica J. Hendy ◽  
Kenneth G. Johnson ◽  
Rebecca Summerfield ◽  
...  
Keyword(s):  
Neural Network ◽  
Traditional Method ◽  
Linear Extension ◽  
Skeletal Growth ◽  
Micro Computed Tomography ◽  
Skeletal Density ◽  
X Ray ◽  
3D Space ◽  
Density Banding ◽  
Growth Banding

AbstractX-ray micro–computed tomography (µCT) is increasingly used to record the skeletal growth banding of corals. However, the wealth of data generated is time consuming to analyse for growth rates and colony age. Here we test an artificial intelligence (AI) approach to assist the expert identification of annual density boundaries in small colonies of massive Porites spanning decades. A convolutional neural network (CNN) was trained with µCT images combined with manually labelled ground truths to learn banding-related features. The CNN successfully predicted the position of density boundaries in independent images not used in training. Linear extension rates derived from CNN-based outputs and the traditional method were consistent. In the future, well-resolved 2D density boundaries from AI can be used to reconstruct density surfaces and enable studies focused on variations in rugosity and growth gradients across colony 3D space. We recommend the development of a community platform to share annotated images for AI.

scholarly journals On the temperature of some fishes of the genus thunnus

1837 ◽  
Vol 3 ◽  
pp. 327-328 ◽  
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Blood Vessels ◽  
Internal Structure ◽  
Surrounding Medium ◽  
Large Size ◽  
Considerable Portion ◽  
Adequate Idea ◽  
The Common ◽  
Respiratory Apparatus

The author had occasion to observe, many years ago, that the Bonito ( Thynnus pelamys , Cuv.) had a temperature of 99° of Fahr. when the surrounding medium was 80°·5,and that it, therefore, constituted an exception to the generally received rule that fishes are universally cold-blooded. Having found that the gills of the common Thunny of the Mediterranean ( Thynnus vulgaris , Cuv.) were supplied with nerves of unusual magnitude, that the heart of this latter fish was very powerful, and that its muscles were of a dark red colour, he was led to conjecture that it might, like the Bonito, be also warm-blooded; and this opinion is corroborated by the testimony of several intelligent fisher-men. The author endeavours to extend this analogy to other species of the same family, which, according to the reports of the fishermen of whom he made inquiries, have a high temperature, and in whose internal structure he noticed similar peculiarities as in the Thunny; namely, very large branchial nerves, furnished with ganglia of considerable size. In this respect he considers that in these fishes the branchial system of organs makes an approximation to the respiratory apparatus of the Mammalia, and that it probably contributes to the elevation of temperature, resulting from the more energetic respiration which he supposes to be exercised by these organs. He, however, thinks it not improbable that these fish may possess means of generating heat peculiar to themselves, and of which at present we have no adequate idea. He conceives that the situation of the kidneys, of which a considerable portion is even higher than the stomach, and posterior to the gills, and which are of large size, and well supplied with nerves and blood-vessels, may possibly act a part in the production of an elevated temperature; but, on the whole, he is disposed to ascribe the greatest share of this effect to the superior magnitude of the branchial nerves.

Growth form and population genetic structure ofAzorella selagoon sub-Antarctic Marion Island

2008 ◽  
Vol 20 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Elizabeth Mortimer ◽  
Melodie A. McGeoch ◽  
Savel R. Daniels ◽  
Bettine Jansen van Vuuren
Keyword(s):  
Sequence Variation ◽  
Growth Form ◽  
Fragment Length Polymorphism ◽  
Sequence Data ◽  
Plant Cover ◽  
Keystone Species ◽  
Growth Dynamics ◽  
Marion Island ◽  
Genetic Studies ◽  
Cushion Plant

AbstractSeven community complexes have been described across sub-Antarctic Marion Island, amongst these fellfield that comprise low plant cover dominated byAzorella selagoHook. f.Azorellais considered a keystone species since it forms nutrient rich environments for microarthropod communities and epiphytic plants. Two distinct growth forms typifyAzorella, namely discrete cushions and continuous mats. Whether these continuous mats normally consist of a single large cushion individual, or whether several individual plants merge, interdigitating to form a continuous area, remains unclear. As such, it is important to obtain some measure ofAzorellagrowth dynamics before embarking on phylogeographic studies. Previous genetic studies indicated that several microarthropod species are significantly substructured across Marion Island, but it remains unclear whether similar subdivisions characterizeAzorella. We used chloroplast sequence data (trnH-psbA) and amplified fragment length polymorphism (AFLP) to investigate these questions. No sequence variation characterized thetrnH-psbA region inAzorellaacross Marion Island. In contrast, the AFLP results indicated that anA. selagomat comprises multiple individuals. We argue that mats can be formed through at least two processes namely fragmentation, where parts of the cushion plant die off creating open areas for the establishment of different individuals and/or high density of interdigitating individuals merging to form the mat. Fragment data further indicated significant substructure forAzorellaacross Marion Island (FST = 0.101,P = 0.01) and we attribute this to past vicariance.

scholarly journals The Predictability Limit of Ocean Mesoscale Eddy Tracks in the Kuroshio Extension Region

2021 ◽  
Vol 8 ◽  
Author(s):  
Yao Meng ◽  
Hailong Liu ◽  
Ruiqiang Ding ◽  
Pengfei Lin ◽  
Mengrong Ding ◽  
...  
Keyword(s):  
Kuroshio Extension ◽  
Mesoscale Eddy ◽  
Growth Dynamics ◽  
Northern Region ◽  
Eastern Region ◽  
Limit Values ◽  
Surface Ocean ◽  
Large Size ◽  
High Predictability ◽  
The Kuroshio

In this study, the nonlinear local Lyapunov exponent and nonlinear error growth dynamics are employed to estimate the predictability limit of oceanic mesoscale eddy (OME) tracks quantitatively using three datasets. The results show that the mean predictability limit of OME tracks is about 53 days for cyclonic eddy (CE) and 52 days for anticyclonic eddy (AE) in the Kuroshio Extension (KE). The predictability limit varies spatially. The predictability limit of OME tracks is higher for the eastern region (about 62.5 days) than that for the western part (about 46 days). The CEs (AEs) predictability limit is relatively high in the southern (northern) region. Additionally, the lifetime, amplitude, and radius of OME are closely related to the predictability limit. The long-lived, large-amplitude, and large-sized OMEs tend to be more predictable. The eastern region often generates long-lived and large-size OMEs, thereby obtaining a higher predictability limit of OME tracks. Furthermore, the relationship between the predictability limit and the smoothness of the OME tracks was investigated using a metric to describe the track’s complexation. Usually, OMEs with high predictability limit values often show extender and smoother trajectories. The effects of the surface ocean circulations and the surface winds are also investigated. The strong and energetic currents lead to a short limitation in the west region.

Skeletal growth dynamics linked to trace-element composition in the scleractinian coral Pocillopora damicornis

2012 ◽  
Vol 99 ◽  
pp. 146-158 ◽  
Author(s):  
Chloe Brahmi ◽  
Christophe Kopp ◽  
Isabelle Domart-Coulon ◽  
Jarosław Stolarski ◽  
Anders Meibom
Keyword(s):  
Trace Element ◽  
Scleractinian Coral ◽  
Growth Dynamics ◽  
Trace Element Composition ◽  
Element Composition ◽  
Skeletal Growth ◽  
Pocillopora Damicornis

scholarly journals Parallel analysis and MBI-HSS: How many factors?

2013 ◽  
pp. 247-248
Author(s):  
Cesar Merino Soto ◽  
Marisol Angulo Ramos
Keyword(s):  
Factor Analysis ◽  
Internal Structure ◽  
Health Professionals ◽  
Human Services ◽  
Empirical Support ◽  
Maslach Burnout Inventory ◽  
Parallel Analysis ◽  
Alpha Coefficient ◽  
Total Group ◽  
Hierarchical Factor Analysis

It has been only recently possible to validate the Maslach Burnout Inventory-Human Services Survey (MBI-HSS)1 among health professionals of Cali2, an important step for using this instrument with local empirical support in regard to its reliability of scoring and internal structure. However, two aspects of this analysis can be considered as methodological weaknesses. First, the Cronbach alpha coefficient was calculated for the total group of items, and this is absolutely inappropriate because: a)the authors did not demonstrate empirical support for accomplishing this (e.g., a hierarchical factor analysis), b) the literature indicates that factors in the MBI-HSS are generally independent, a characteristic also reported by Córdoba et al. 2,

Coherency loss in γ' precipitates in nickel-base superalloy

1983 ◽  
Vol 41 ◽  
pp. 244-245
Author(s):  
R. A. Ricks ◽  
Angus J. Porter
Keyword(s):  
Lattice Mismatch ◽  
Lattice Parameter ◽  
Nickel Base Superalloy ◽  
Large Size ◽  
The Matrix ◽  
Nimonic 80A ◽  
Interfacial Dislocations ◽  
Nickel Base ◽  
Coherency Loss ◽  
Nimonic 115

During a recent investigation concerning the growth of γ' precipitates in nickel-base superalloys it was observed that the sign of the lattice mismatch between the coherent particles and the matrix (γ) was important in determining the ease with which matrix dislocations could be incorporated into the interface to relieve coherency strains. Thus alloys with a negative misfit (ie. the γ' lattice parameter was smaller than the matrix) could lose coherency easily and γ/γ' interfaces would exhibit regularly spaced networks of dislocations, as shown in figure 1 for the case of Nimonic 115 (misfit = -0.15%). In contrast, γ' particles in alloys with a positive misfit could grow to a large size and not show any such dislocation arrangements in the interface, thus indicating that coherency had not been lost. Figure 2 depicts a large γ' precipitate in Nimonic 80A (misfit = +0.32%) showing few interfacial dislocations.

X-ray microtomography

1988 ◽  
Vol 46 ◽  
pp. 998-999
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico
Keyword(s):  
Computed Tomography ◽  
Internal Structure ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Tissue Structure ◽  
Individual Element ◽  
X Ray ◽  
Non Invasive ◽  
Panoramic Imaging ◽  
Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

Sign in / Sign up

Export Citation Format

Share Document