scholarly journals Correlations of some Neoproterozoic carbonate-dominated successions in South America based on high-resolution chemostratigraphy

2016 ◽  
Vol 46 (3) ◽  
pp. 439-488 ◽  
Author(s):  
Alcides Nobrega Sial ◽  
Claudio Gaucher ◽  
Aroldo Misi ◽  
Paulo Cesar Boggiani ◽  
Carlos José Souza de Alvarenga ◽  
...  
Keyword(s):  
High Resolution ◽  
South America ◽  
Carbonate Platform ◽  
Point Of View ◽  
Passive Margins ◽  
C Isotopes ◽  
Marine Carbonate ◽  
Rodinia Supercontinent ◽  
High Level ◽  
Orogenic Belts

ABSTRACT: This report reviews and incorporates new elemental and isotope chemostratigraphic data for correlation of Neoproterozoic carbonate-dominated successions in South America (Argentina, Bolivia, Brazil, Paraguay and Uruguay). These thick mixed carbonate/siliciclastic successions were largely deposited in epicontinental basins or accumulated on passive margins on the edges of cratons (e.g. São Francisco, Amazonia, Rio Apa Block, Pampia and Río de la Plata paleocontinents) during extensional events related to the rifting of the Rodinia Supercontinent. From the stratigraphic point of view, these successions occur as three mega-sequences: glaciogenic, marine carbonate platform (above glaciomarine diamictites or rift successions), and dominantly continental to transitional siliciclastics. In the orogenic belts surrounding cratons, carbonate-dominated successions with important volcanoclastic/siliciclastic contribution have been, in most cases, strongly deformed. The precise ages of these successions remain a matter of debate, but recently new paleontological and geochronological data have considerably constrained depositional intervals. Here, we report high-resolution C, O, Sr, and S isotope trends measured in well-preserved sample sets and mainly use Sr and C isotopes in concert with lithostratigraphic/biostratigraphic observations to provide detailed correlations of these successions. The establishing of a high-level and definite chemostratigraphic correlation between Neoproterozoic basins in South America is the main goal of this work.

scholarly journals Sedimentology and chemostratigraphy of a Valanginian carbonate succession from the Baja Guajira Basin, northern Colombia

2016 ◽  
Vol 46 (suppl 1) ◽  
pp. 163-180 ◽  
Author(s):  
Juan Carlos Silva-Tamayo ◽  
Catalina Ramirez ◽  
Mario Lara ◽  
Alcides Nobrega Sial ◽  
David Trujillo ◽  
...  
Keyword(s):  
South America ◽  
Carbonate Platform ◽  
Sedimentary Basins ◽  
Tectonic Block ◽  
Positive Anomaly ◽  
Oceanic Anoxic Event ◽  
Marine Carbonate ◽  
Anoxic Event ◽  
Northern South America ◽  
Carbonate Factory

ABSTRACT: The Kesima Member of the Palanz Formation constitutes the first record of Cretaceous marine sedimentation along the Baja Guajira Basin, northern Colombia. Sedimentologic and petrographic analyses suggest a deposition along a coral reef dominated rimmed carbonate platform. 87Sr/86Sr values between 0.707350 and 0.707400 suggest a Valanginian (136 - 132 Ma) depositional age for the Kesima Member. A positive anomaly on the δ13C values of ~2.2‰ suggests that this rimmed carbonate platform registered the Valanginian Weissert oceanic anoxic event. Although the Weissert oceanic anoxic event resulted on a major drowning of the Circum Tethyan carbonate platforms, it seems to have not affected those from the Circum Caribbean, where several shallow marine carbonate platform successions crop out. The Kesima Member displays a change from an organically produced carbonate factory into an inorganically produced, ooids dominated, carbonate factory during the peak of the Weissert event δ13C anomaly. This change in the carbonate factory, which may represent a major perturbation of the marine carbonate budget along tropical settings during the Weissert event, coincides with a major decrease in global sea level. Finally, the age of the Kesima Member is considerably older than that of other Cretaceous carbonate successions cropping out in other northern South America sedimentary basins (i.e. Perija-Merida, Cesar-Rancheria). Differences in the timing of the Cretaceous marine incursion along northern South America, together with the differences in the Triassic-Jurassic stratigraphy of several sedimentary basins in northern South America, suggest that the Baja Guajira and Maracaibo basins remained as an isolated tectonic block separated from northern South America after the breakup of Pangea.

High-resolution electron microscopy of Cu2O surfaces

1986 ◽  
Vol 44 ◽  
pp. 396-397
Author(s):  
V. Castano ◽  
W. Krakow
Keyword(s):  
High Resolution ◽  
Natural Extension ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Initial Oxidation ◽  
System A ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Atomic Surface ◽  
Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

Theoretical And Practical Design Considerations for Ultra-High Resolution Electron Lenses

1980 ◽  
Vol 38 ◽  
pp. 266-269
Author(s):  
Y. Harada ◽  
K. Tsuno ◽  
Y. Arai
Keyword(s):  
Optical Properties ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Point Of View ◽  
Pole Piece ◽  
Axial Field ◽  
Design Considerations ◽  
Resolution Electron ◽  
Practical Design ◽  
Peak Flux

Magnetic objective lenses, from the point of view of pole piece geometry, can he roughly classified into two types, viz., symmetrical and asymmetrical. In the case of the former, the optical properties have been calculated by several authors1-3) and the results would appear to suggest that, in order to reduce the spherical and chromatic aberration coefficients, Cs and Cc, it is necessary to decrease the half-width value of the axial field distribution and to increase the peak flux density. The expressions for either minimum Cs or minimum Cc were presented in the form of ‘universal’ curves by Mulvey and Wallington4).

Territorial Distribution of Alcohol and Drug Addictions Mortality Concerning Regional Disparities in the Slovak Republic from Year 1996 to Year 2015

2020 ◽  
Keyword(s):  
Mortality Rate ◽  
Slovak Republic ◽  
Regional Disparities ◽  
Point Of View ◽  
Extreme Position ◽  
Data Set ◽  
Female Sex ◽  
Male Sex ◽  
The Individual ◽  
High Level

BACKGROUND: This paper deals with territorial distribution of the alcohol and drug addictions mortality at a level of the districts of the Slovak Republic. AIM: The aim of the paper is to explore the relations within the administrative territorial division of the Slovak Republic, that is, between the individual districts and hence, to reveal possibly hidden relation in alcohol and drug mortality. METHODS: The analysis is divided and executed into the two fragments – one belongs to the female sex, the other one belongs to the male sex. The standardised mortality rate is computed according to a sequence of the mathematical relations. The Euclidean distance is employed to compute the similarity within each pair of a whole data set. The cluster analysis examines is performed. The clusters are created by means of the mutual distances of the districts. The data is collected from the database of the Statistical Office of the Slovak Republic for all the districts of the Slovak Republic. The covered time span begins in the year 1996 and ends in the year 2015. RESULTS: The most substantial point is that the Slovak Republic possesses the regional disparities in a field of mortality expressed by the standardised mortality rate computed particularly for the diagnoses assigned to the alcohol and drug addictions at a considerably high level. However, the female sex and the male sex have the different outcome. The Bratislava III District keeps absolutely the most extreme position. It forms an own cluster for the both sexes too. The Topoľčany District bears a similar extreme position from a point of view of the male sex. All the Bratislava districts keep their mutual notable dissimilarity. Contrariwise, evaluation of a development of the regional disparities among the districts looks like notably heterogeneously. CONCLUSIONS: There are considerable regional discrepancies throughout the districts of the Slovak Republic. Hence, it is necessary to create a common platform how to proceed with the solution of this issue.

Ground state molecular parameters of phosphine, PH3, from the simultaneous analysis of the high-resolution infrared, microwave and submillimeterwave spectra

1985 ◽  
Vol 50 (11) ◽  
pp. 2480-2492 ◽  
Author(s):  
Soňa Přádná ◽  
Dušan Papoušek ◽  
Jyrki Kauppinen ◽  
Sergei P. Belov ◽  
Andrei F. Krupnov ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Ground State ◽  
Unitary Transformation ◽  
Point Of View ◽  
Acoustic Detection ◽  
Molecular Parameters ◽  
Microwave Spectrometer ◽  
Fourier Transform Spectra ◽  
First Time

Fourier transform spectra of the ν2 band of PH3 have been remeasured with 0.0045 cm-1 resolution. Ground state combination differences from these data have been fitted simultaneously with the microwave and submillimeterwave data to determine the ground state spectroscopical parameters of PH3 including the parameters of the Δk = ± 3n interactions. The correlation between the latter parameters has been discussed from the point of view of the existence of two equivalent effective rotational operators which are related by a unitary transformation. The ΔJ = 0, +1, ΔK = 0 (A1 ↔ A2, E ↔ E) rotational transitions in the ν2 and ν4 states have been measured for the first time by using a microwave spectrometer and a radiofrequency spectrometer with acoustic detection.

scholarly journals Radiological Parameters Review for Choanal Atresia

2021 ◽  
Vol 13 (2) ◽  
pp. 302-311
Author(s):  
Daniela Messineo ◽  
Maryia Chernikava ◽  
Valeria Pasquali ◽  
Serena Bertin ◽  
Mario Ciotti ◽  
...  
Keyword(s):  
Retrospective Study ◽  
High Resolution ◽  
Surgical Approach ◽  
Choanal Atresia ◽  
Point Of View ◽  
Control Group ◽  
Study Group ◽  
Control Groups ◽  
Imaging Parameters ◽  
Multiplanar Imaging

(1) Background: The study aims to identify which imaging parameters are necessary for a new correct surgical approach in the study of choanal atresia, and which anatomical findings are essential for correct planning of endoscopic treatment in choanal atresia. (2) Methods: In this retrospective study, 19 patients with choanal atresia had high-resolution multiplanar imaging (14 cases aged ≤1 year and 5 cases aged 1 to 3 years) and 35 patients in the control group similarly distributed by age. Fourteen variables, the most relevant from a surgical point of view, were selected and measured. A comparison was made between the averages of the study group and the different control groups, either directly observed or selected from the literature, using Pearson’s correlation. (3) Results: In 14 out of 26 cases, the differences were statistically significant. There was a correlation between the structures assessed, such as choanal height, rostrum height, and age. (4) Conclusions: Thanks to volumetric reformatting, this work identified and provided the clinician with useful information that helped choose the correct surgical approach. Furthermore, it focused on which imaging parameters are necessary to improve the planning of the surgical correction of choanal atresia.

Arising of Informal Women's Learn-to-code Communities

2021 ◽  
Vol 21 (2) ◽  
pp. 1-24
Author(s):  
Louise Ann Lyon ◽  
Chelsea Clayton
Keyword(s):  
Learning Community ◽  
Virtual Communities ◽  
Point Of View ◽  
Customer Relationship ◽  
Activity System ◽  
Learning Group ◽  
Management Platform ◽  
High Level ◽  
Verbal Encouragement ◽  
Activity Systems Analysis

Female-focused, grassroots communities purporting to help women learn to code are popping up in a variety of settings, indicating the motivation on the part of the participants to evade male-dominated settings while learning. However, little is known about how these groups function as an activity system. With current technology enabling the forming of virtual communities and the meteoric rise in use of the Salesforce CRM (customer relationship management) platform, a group of women have formed a coaching and learning community designed to help women move from Salesforce administrators to software developers through learning to code. We used activity systems analysis (ASA) to investigate this real-world instance of the larger phenomenon using an ethnographic approach. We used ASA to organize and make sense of the data by first creating a table listing the points on the activity system triangle (subject, rules, object, etc.) and filling in the points of the triangle based on the design of the coaching and learning group as described by participants; this gave us a high-level view of the activity system. To understand the subjects’ point of view of the system, we then created a new column in the table to fill in themes that emerged from our qualitative data analysis organized by dimension of the activity system. This process enabled us to capture the activity and the voices of participants as well as tensions that had emerged in the system. Findings show a range of outcomes, from participants crediting the group as a kickstart to the journey to successfully landing a job as a developer to members stalling in their progress after involvement. Results also show that purposeful tensions of welcoming novice questions and offering unsolicited verbal encouragement built into the activity system create a welcoming, safe environment for women learning to code.

Characterization of Tilt Boundaries by Ultra High Resolution Electron Microscopy

1984 ◽  
Vol 41 ◽  
Author(s):  
W. Krakow ◽  
J. T. Wetzel ◽  
D. A. Smith ◽  
G. Trafas
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Structural Information ◽  
Theoretical Work ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Experimental Point ◽  
Structure Information ◽  
Resolution Electron ◽  
Tilt Boundaries

AbstractA high resolution electron microscope study of grain boundary structures in Au thin films has been undertaken from both a theoretical and experimental point of view. The criteria necessary to interpret images of tilt boundaries at the atomic level, which include electron optical and specimen effects, have been considered for both 200kV and the newer 400kV medium voltage microscopes. So far, the theoretical work has concentrated on two different [001] tilt bounda-ries where a resolution of 2.03Å is required to visualize bulk lattice structures on either side of the interface. Both a high angle boundary, (210) σ=5, and a low angle boundary, (910) σ=41, have been considered. Computational results using multislice dynamical diffraction and image simulations of relaxed bounda-ries viewed edge-on and with small amounts of beam and/or specimen inclina-tion have been obtained. It will be shown that some structural information concerning grain boundary dislocations can be observed at 200kV. However, many difficulties occur in the exact identification of the interface structure viewed experimentally for both [001] and [011] boundaries since the resolution required is near the performance limit of a 200kV microscope. The simulated results at 400kV indicate a considerable improvement will be realized in obtain-ing atomic structure information at the interface.

scholarly journals Designing Science and Technology Park of Tabriz with Organic Architecture Approach, Inspired by Ants' Nest Algorithm

2016 ◽  
Vol 11 (1) ◽  
pp. 134
Author(s):  
Zahra Ghannadian ◽  
Shahriyar Shaghagh
Keyword(s):  
Science And Technology ◽  
Point Of View ◽  
Advanced Technology ◽  
Modern Culture ◽  
Science And Technology Parks ◽  
Technology Park ◽  
Technology Parks ◽  
Science And Technology Park ◽  
Organic Architecture ◽  
High Level

Establishment of every urban element in its appropriate position requires advanced technology and science from geographical and climatic point of view. This is accompanied and synchronous with modern culture born by supreme and high level of training and education in the society. In this regard, one of the main objectives of the architectures' union is to establish science and Technology Park with the aim of facilitating and accelerating science and technology transmission from university to the society and country.Tabriz city is considered as one of the most important academic and industrial cities in the country. Establishing science and technology parks can be effective in scientific, economic and social development of the country and province. Employing organic methods in architecture to use natural energies is an effective and useful method and its structure produces less pollution. Using philosophical and introductory issues and views of technology and establishing technology parks, present article proceeds on issues of organic architecture with new approach which is inspired by ants' nest algorithm and presents a new experience of architecture in the form of Science and Technology Park.

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