A Review of Evolutionary Trends in Carbonate Hardground Communities

1990 ◽  
Vol 5 ◽  
pp. 137-152 ◽  
Author(s):  
Mark A. Wilson ◽  
Timothy J. Palmer
Keyword(s):  
Early Cambrian ◽  
Spatial Relationships ◽  
Evolutionary Trends ◽  
Physical Resource ◽  
Physical Conditions ◽  
Marine Carbonate ◽  
Competitive Hierarchies ◽  
General Physical ◽  
Sessile Organisms

Ancient and modern marine carbonate hardgrounds offer unusual opportunities to study the evolution of communities from the Early Cambrian into the Holocene. Throughout this time the general physical conditions of a hardground community have been similar. The substrate is hard so sessile organisms must either attach to its surface, nestle in cavities, or bore into it for occupation. These organisms are thus preserved in situ. Since space is often the limiting physical resource, organisms must have ways of obtaining and defending it, and these competitive hierarchies are often preserved in the spatial relationships of the species. Scouring and/or burial in sediment usually marks the end of the brief habitation.

scholarly journals Towards an Understanding of Crystallization by Attachment

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 463
Author(s):  
Haihua Pan ◽  
Ruikang Tang
Keyword(s):  
Capillary Condensation ◽  
Force Measurements ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Driving Mechanisms ◽  
Atomic Force ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Hydration Layers

Crystallization via particle attachment was used in a unified model for both classical and non-classical crystallization pathways, which have been widely observed in biomimetic mineralization and geological fields. However, much remains unknown about the detailed processes and driving mechanisms for the attachment. Here, we take calcite crystal as a model mineral to investigate the detailed attachment process using in situ Atomic Force Microscopy (AFM) force measurements and molecular dynamics simulations. The results show that hydration layers hinder the attachment; however, in supersaturated solutions, ionic bridges are formed between crystal gaps as a result of capillary condensation, which might enhance the aggregation of calcite crystals. These findings provide a more detailed understanding of the crystal attachment, which is of vital importance for a better understanding of mineral formation under biological and geological environments with a wide range of chemical and physical conditions.

Chronology of Sites at Killarney, Canada

1966 ◽  
Vol 31 (4) ◽  
pp. 540-551 ◽  
Author(s):  
E. F. Greenman
Keyword(s):  
Great Lakes ◽  
Lake Huron ◽  
Physical Conditions ◽  
Raised Beaches

AbstractNear Killarney, Canada, three raised beaches of former Great Lakes stages have cultural material in circumstances indicating contemporaneity with the construction of the beaches 7000 B.C. and A.D. 1. The physical conditions demonstrating this contemporaneity are set forth in detail, with illustrations of artifacts in situ in gravels. The several components of two sites are distinguished, and a workshop with most of the artifacts in unfinished condition is described and illustrated. The geology, which involves Postglacial uplift of the Lake Huron basin along with rising and lowering levels, is fully outlined.

Early Cambrian priapulid worms buried with their lined burrows

2006 ◽  
Vol 143 (5) ◽  
pp. 743-748 ◽  
Author(s):  
XI-GUANG ZHANG ◽  
XIAN-GUANG HOU ◽  
JAN BERGSTRÖM
Keyword(s):  
Lower Cambrian ◽  
Southern China ◽  
Early Cambrian ◽  
Exceptional Preservation ◽  
Sediment Layers

Five specimens of the priapulid Maotianshania cylindrica preserved inside their lined burrows were described from the Lower Cambrian Chengjiang deposits near Kunming, southern China. The exceptional preservation suggests that this worm made a dwelling tube by lining within the uppermost sediment layers. This seems to be unique among priapulids in comparison with the Cambrian Selkirkia and Paraselkirkia, as well as some modern priapulid larvae and loriciferans. Taphonomic evidence indicates that the burrow-and-worm specimens are not buried in situ but were moved by storm, tsunami, or turbidity generated currents that are thought to have brought sedimentary material intermittently.

scholarly journals An Evaluation of the Main Physical Features and Circulation Patterns in the Black Sea Basin

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Alina GIRLEANU ◽  
Eugen RUSU
Keyword(s):  
Black Sea ◽  
Warming Trend ◽  
Mitigation Measures ◽  
The Black Sea ◽  
Climate Change Projections ◽  
Black Sea Region ◽  
Circulation Patterns ◽  
General Physical ◽  
Physical Features

Having as target the semi-enclosed basin of the Black Sea, the main purpose of the present paper is to provide an overview of its general physical features and circulation patterns. In order to achieve this goal, more than five decades of data analysis – from  1960 to 2015 – were taken into consideration and the results were checked against known data, both from satellite data over the last two decades and in-situ measurements from earlier decades. The circulation of the Black Sea basin has been studied for almost 400 years, since the Italian Count Luigi Marsigli first described the ‘two layer’ circulation through the Bosphorus Strait in the year 1681. Since climate change projections for the Black Sea region foresee significant impact on the environment in the coming decades, a set of adaptation and mitigation measures is required, therefore more research is needed. Nowadays, the warming trend adds a sense of immediate urgency because according to the National Oceanic and Atmospheric Administration’s National Centre for Environmental Information, July 2020 was the second-hottest month ever recorded for the planet. Its averaged land and ocean surface temperature tied with July 2016 as the second-highest for the month in the 141-year NOAA’s global temperature dataset record, which dates back to 1880. It was 0.92°C above the 20th-century average of 15.8°C, with only 0.01°C less than the record extreme value measured in July of 2019.

scholarly journals Slum Upgrading: Can the 1.5 °C Carbon Reduction Work with SDGs in these Settlements?

2018 ◽  
Vol 3 (2) ◽  
pp. 52-63 ◽  
Author(s):  
Zafu Assefa Teferi ◽  
Peter Newman
Keyword(s):  
Urban Planning ◽  
Addis Ababa ◽  
The Sustainable Development ◽  
Carbon Reduction ◽  
Physical Conditions ◽  
Slum Upgrading ◽  
Inclusive Approach ◽  
Zero Carbon ◽  
Development Goals

The need to improve slum housing is a major urban planning agenda, especially in Africa and Asia. This article addresses whether it seems feasible to do this whilst helping achieve the 1.5 °C agenda, which requires zero carbon power along with enabling the Sustainable Development Goals. Survey data from Jakarta and Addis Ababa on the metabolism and liveability of slums are used to illustrate these issues. The article shows that this is possible due to advances in community-based distributed infrastructure that enable community structures to be retained whilst improving physical conditions. The urban planning implications are investigated to enable these ‘leapfrog’ technologies and a more inclusive approach to slums that enables in situ redevelopment instead of slum clearance, and which could be assisted through climate financing.

Corrections for matrix effects on fluorescence measurement of a multi-platform optical sensor

2016 ◽  
Vol 11 (3) ◽  
pp. 644-660 ◽  
Author(s):  
Chee-Loon Ng ◽  
Yan-Jie Ng ◽  
Qing-Qing Chen ◽  
Harold F. Hemond
Keyword(s):  
Matrix Effect ◽  
Optical Sensor ◽  
Matrix Effects ◽  
Fluorescence Measurement ◽  
Optical Instrument ◽  
Laboratory Sample ◽  
Physical Conditions ◽  
Fluorescence Measurements ◽  
Improve Accuracy

The LEDIF (LED-induced fluorescence) is an in situ optical instrument that utilizes fluorescence, absorbance, and scattering to identify and quantify substances in water bodies. In this study, matrix effects on fluorescence signals caused by inner filtering, temperature, intramolecular deactivation, turbidity, and pH were investigated, and compensation equations developed to correct measured values and improve accuracy. Multiple simultaneous matrix effect corrections were demonstrated with a laboratory sample subjected to known interferences and physical conditions. In general, compensation was found to be important to improve the accuracy of fluorescence measurements.

scholarly journals Radiation forces between dust grains in a plasma

2008 ◽  
Vol 74 (2) ◽  
pp. 145-150
Author(s):  
J. T. MENDONÇA ◽  
L. STENFLO
Keyword(s):  
Incident Radiation ◽  
Repulsive Force ◽  
Repulsive Interaction ◽  
Dust Grains ◽  
Physical Conditions ◽  
Dust Charge ◽  
Radiation Forces ◽  
Definition Of ◽  
General Physical ◽  
Dust Grain

AbstractIn this work we show that a repulsive force between nearby dust grains in a plasma can exist, due to scattering of the incident radiation. Two types of forces are discussed, one of them being formally identical to electrostatic repulsion. This leads to the definition of an effective dust charge of the dust grain, which only depends on the scattering process. Our discussion shows that such a repulsive interaction occurs in quite general physical conditions.

scholarly journals Calliostoma and Akoya of the Californian Marine Province (Gastropoda: Calliostomatidae)

The Festivus ◽  
2019 ◽  
Vol 51 (1) ◽  
pp. 11-28
Author(s):  
Paul Tuskes ◽  
Ann McGowan-Tuskes
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Shell Morphology ◽  
Species Analysis ◽  
Shallow Water Species ◽  
Unique Species ◽  
Sessile Organisms ◽  
A New Species ◽  
Water Species

Fifteen species of Calliostomatidae are known to occur in the Californian marine province. Biological observations in situ on shallow water species indicates they are primarily carnivores, feeding on sessile organisms such as sponge, bryozoan, hydrozoa, diatoms and various Cnidaria. Adult variation, distribution, depth, and habitat are discussed and a summary of distribution records are provided for unique species. Analysis of shell morphology indicates Akoya titanium is a synonymy of A. platinum. A review of museum material also suggests that C. splendens appears to be correctly placed as a synonym of C. supragranosm. A new species of Calliostoma from the most southern portion of the Californian marine province is described and illustrated.

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