scholarly journals The Effect of Aqueous Alteration and Metamorphism in the Survival of Presolar Silicate Grains in Chondrites

2009 ◽  
Vol 26 (3) ◽  
pp. 289-296 ◽  
Author(s):  
Josep M. Trigo-Rodriguez ◽  
Jürgen Blum
Keyword(s):  
Relative Abundance ◽  
Shock Metamorphism ◽  
Clear Pattern ◽  
Aqueous Alteration ◽  
Sample Return ◽  
Presolar Grains ◽  
Thermal Metamorphism ◽  
General Overview ◽  
Marco Polo ◽  
Different Types

AbstractRelatively small amounts (typically between 2 and 200 ppm) of presolar grains have been preserved in the matrices of chondritic meteorites. The measured abundances of the different types of grains are highly variable from one chondrite to another, but are higher in unequilibrated chondrites that have experienced little or no aqueous alteration and/or metamorphic heating than in processed meteorites. A general overview of the abundances measured in presolar grains (particularly the recently identified presolar silicates) contained in primitive chondrites is presented. Here we will focus on the most primitive chondrite groups, as typically the highest measured abundances of presolar grains occur in primitive chondrites that have experienced little thermal metamorphism. Looking at the most aqueously altered chondrite groups, we find a clear pattern of decreasing abundance of presolar silicate grains with increasing levels of aqueous alteration. We conclude that measured abundances of presolar grains in altered chondrites are strongly biased by their peculiar histories. Scales quantifying the intensity of aqueous alteration and shock metamorphism in chondrites could correlate with the content of presolar silicates. To do this it would be required to infer the degree of destruction or homogenization of presolar grains in the matrices of primitive meteorites. To get an unbiased picture of the relative abundance of presolar grains in the different regions of the protoplanetary disk where first meteorites consolidated, future dedicated studies of primitive meteorites, IDPs, and collected materials from sample-return missions (like e.g. the planned Marco Polo) are urgently required.

Meteorite Mineralogy

2020 ◽  
Author(s):  
Alan E. Rubin ◽  
Chi Ma
Keyword(s):  
Outer Space ◽  
Matrix Material ◽  
Parent Body ◽  
Primary Phase ◽  
Shock Metamorphism ◽  
Aqueous Alteration ◽  
Fine Grained ◽  
Thermal Metamorphism ◽  
Geochemical Properties ◽  
Gaseous Envelopes

Meteorites are rocks from outer space that reach the Earth; more than 60,000 have been collected. They are derived mainly from asteroids; a few hundred each are from the Moon and Mars; some micrometeorites derive from comets. By mid 2020, about 470 minerals had been identified in meteorites. In addition to having characteristic petrologic and geochemical properties, each meteorite group has a distinctive set of pre-terrestrial minerals that reflect the myriad processes that the meteorites and their components experienced. These processes include condensation in gaseous envelopes around evolved stars, crystallization in chondrule melts, crystallization in metallic cores, parent-body aqueous alteration, and shock metamorphism. Chondrites are the most abundant meteorites; the major components within them include chondrules, refractory inclusions, opaque assemblages, and fine-grained silicate-rich matrix material. The least-metamorphosed chondrites preserve minerals inherited from the solar nebula such as olivine, enstatite, metallic Fe-Ni, and refractory phases. Other minerals in chondrites formed on their parent asteroids during thermal metamorphism (such as chromite, plagioclase and phosphate), aqueous alteration (such as magnetite and phyllosilicates) and shock metamorphism (such as ringwoodite and majorite). Differentiated meteorites contain minerals formed by crystallization from magmas; these phases include olivine, orthopyroxene, Ca-plagioclase, Ca-pyroxene, metallic Fe-Ni and sulfide. Meteorites also contain minerals formed during passage through the Earth’s atmosphere and via terrestrial weathering after reaching the surface. Whereas some minerals form only by a single process (e.g., by high-pressure shock metamorphism or terrestrial weathering of a primary phase), other meteoritic minerals can form by several different processes, including condensation, crystallization from melts, thermal metamorphism, and aqueous alteration.

scholarly journals Treating Children With Speech Sound Disorders: Development of a Tangible Artefact Prototype

10.2196/13861 ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. e13861
Author(s):  
Joaquim Santos ◽  
Mário Vairinhos ◽  
Luis M T Jesus
Keyword(s):  
Serious Games ◽  
Qualitative Data ◽  
Speech Sound ◽  
Tangible Interaction ◽  
Tangible User Interface ◽  
Clear Pattern ◽  
Speech Sound Disorders ◽  
Ethnographic Approach ◽  
Different Types ◽  
Traditional Game

Background A prototype of a tangible user interface (TUI) for a fishing game, which is intended to be used by children with speech sound disorders (SSD), speech and language therapists (SLTs), and kindergarten teachers and assistants (KTAs) and parents alike, has been developed and tested. Objective The aim of this study was to answer the following question: How can TUIs be used as a tool to help in interventions for children with SSD? Methods To obtain feedback and to ensure that the prototype was being developed according to the needs of the identified target users, an exploratory test was prepared and carried out. During this test using an ethnographic approach, an observation grid, a semistructured questionnaire, and interviews were used to gather data. A total of 4 different types of stakeholders (sample size of 10) tested the prototype: 2 SLTs, 2 KTAs, and 6 children. Results The analysis of quantitative and qualitative data revealed that the prototype addresses the existing needs of SLTs and KTAs, and it revealed that 5 out of 6 (83%) children enjoyed the activity. Results also revealed a high replay value, with all children saying they would play more. Conclusions Serious games and tangible interaction for learning and problem solving serve both teachers and children, as children enjoy playing, and, through a playful approach, learning is facilitated. A clear pattern was observed: Children enjoyed playing, and numerous valid indicators showed the transposition of the traditional game into the TUI artefact was successful. The game is varied and rich enough to be attractive and fun. There is a clear need and interest in similar objects from SLTs and educators. However, the process should be even more iterative, with a multidisciplinary team, and all end users should be able to participate as co-designers.

scholarly journals Utilizing drone technology in the civil engineering

2019 ◽  
Vol 14 (1) ◽  
pp. 27-37
Author(s):  
Matúš Tkáč ◽  
Peter Mésároš
Keyword(s):  
Real Time ◽  
Unmanned Aerial Vehicle ◽  
Civil Engineering ◽  
Aerial Images ◽  
General Overview ◽  
Aerial Photogrammetry ◽  
Different Types ◽  
Aerial Vehicle

Abstract An unmanned aerial vehicle (UAVs), also known as drone technology, is used for different types of application in the civil engineering. Drones as a tools that increase communication between construction participants, improves site safety, uses topographic measurements of large areas, with using principles of aerial photogrammetry is possible to create buildings aerial surveying, bridges, roads, highways, saves project time and costs, etc. The use of UAVs in the civil engineering can brings many benefits; creating real-time aerial images from the building objects, overviews reveal assets and challenges, as well as the broad lay of the land, operators can share the imaging with personnel on site, in headquarters and with sub-contractors, planners can meet virtually to discuss project timing, equipment needs and challenges presented by the terrain. The aim of this contribution is to create a general overview of the use of UAVs in the civil engineering. The contribution also contains types of UAVs used for construction purposes, their advantages and also disadvantages.

Blood cell morphology of the Moorish gecko, Tarentola mauritanica

2007 ◽  
Vol 28 (4) ◽  
pp. 503-508 ◽  
Author(s):  
Fabio Pupin ◽  
Roberto Sacchi ◽  
Stefano Scali ◽  
Alessandra Binda ◽  
Marco Zuffi ◽  
...  
Keyword(s):  
Blood Cell ◽  
Relative Abundance ◽  
Cell Morphology ◽  
Fourth Type ◽  
Different Types ◽  
Blood Cell Morphology

Abstract The morphology of erythrocytes, trombocytes, monocytes, basophils and lymphocytes on Moorish geckos (Tarentola mauritanica) is quite similar to that of other reptiles, even though some peculiarities were detected for heterophils and eosinophils. Moreover, we found a fourth type of granulocyte whose morphology highly differs from both heterophils and eosinophils. Sexually-based differences in the relative abundance of different types of leukocytes was detected: lymphocytes were the most frequent in females, while heterophils and eosinophils prevailed in males. Interestingly, in most individuals we found intra-erythrocytic vacuoles whose structure is similar to that previously described as Chelonoplasma in tortoises and Serpentoplasma in snakes.

Occurrence and relative abundance of mosquitoes in stormwater retention facilities in North Carolina, USA

2006 ◽  
Vol 54 (6-7) ◽  
pp. 315-321 ◽  
Author(s):  
W.F. Hunt ◽  
C.S. Apperson ◽  
S.G. Kennedy ◽  
B.A. Harrison ◽  
W.G. Lord
Keyword(s):  
North Carolina ◽  
Relative Abundance ◽  
Seasonal Changes ◽  
Stormwater Management ◽  
Biological Diversity ◽  
Mosquito Species ◽  
Structural Complexity ◽  
Different Types ◽  
Retention Structures ◽  
Stormwater Retention

Throughout the 2004 mosquito season, 52 stormwater retention facilities were sampled to characterize the seasonal occurrence and relative abundance of mosquito species in relation to the structural complexity and biological diversity of the facilities. The three different types of facilities included standard wet ponds (n=20), innovative ponds (n=14), and wetland ponds (n=18). All retention structures were sampled at the beginning, middle and end of the mosquito season so that seasonal changes in mosquito production could be characterized. Overall samplings, mosquitoes were collected from 34% of the retention structures. Fourteen species representing 7 genera were collected, but only 5 species (Culex erraticus, Cx. territans, Anophelesquadrimaculatus, An. punctipennis and Uranotaenia sapphirina) were commonly collected in all three types of stormwater management facilities. In general, the seasonal prevalence and relative abundance of mosquito species did not vary among three types of retention structures. A significant association (P<0.01) between the presence of mosquito larvae or pupae and the absence of mosquitofish was found for innovative and wetland stormwater retention facilities but not for standard retention facilities (P>0.05).

THE INTERACTION OF HIGHER PLANTS AND SOIL MICRO-ORGANISMS: I. MICROBIAL POPULATION OF RHIZOSPHERE OF SEEDLINGS OF CERTAIN CULTIVATED PLANTS

1940 ◽  
Vol 18c (7) ◽  
pp. 307-317 ◽  
Author(s):  
M. I. Timonin
Keyword(s):  
New Species ◽  
Relative Abundance ◽  
Microbial Population ◽  
Higher Plants ◽  
Cultivated Plants ◽  
Plating Method ◽  
Different Types ◽  
Micro Organisms ◽  
A New Species

The microbial population in the rhizosphere of wheat, oats, alfalfa, and peas was studied and the relative abundance of different types of micro-organisms recorded. By means of the plating method it was found that bacteria and actinomycetes were 7 to 71 times greater in the rhizosphere than in the soil distant from the roots, whereas fungi were but 0.75 to 3.1 times more numerous.Different varieties of plants affected the activity of the various groups of soil micro-organisms differently. Thus fungi were more numerous in the rhizosphere of oats, and bacteria in the rhizosphere of alfalfa. Seventeen genera of fungi were represented in isolates from the rhizosphere of seedlings and the soil distant from the roots. However, no marked difference was observed in the types isolated from the rhizosphere of different varieties of seedlings. A fungus isolated from the rhizosphere of alfalfa proved to be a new species and the genus Spicularia Persoon was amended to include it.

Video pollution on the Web

First Monday ◽  
2010 ◽  
Author(s):  
Fabricio Benevenuto ◽  
Tiago Rodrigues ◽  
Virgílio A.F. Almeida ◽  
Jussara Almeida ◽  
Marcos Gonçalves ◽  
...  
Keyword(s):  
User Satisfaction ◽  
Search Engines ◽  
Negative Impact ◽  
Multimedia Content ◽  
User Perspective ◽  
Daily Lives ◽  
Video Sharing ◽  
General Overview ◽  
Different Types ◽  
The Web

Videos have become a predominant part of users’ daily lives on the Web, especially with the emergence of video sharing services, such as YouTube. Part of the huge success of multimedia content in the Web is due to the change on the user perspective from content consumer to content creator. However, by allowing users to publicize their independently generated content, video sharing networks become susceptible to different types of pollution. As example, users can pollute the system spreading video messages containing undesirable content. Users can also associate metadata with videos in attempt to fool video search engines (i.e., popular tags, but unrelated to the content). Moreover, users can upload identical videos, generating duplicates of the same content on the system. Such pollution compromises not only the user satisfaction, but it also consumes system resources and can impact negatively aspects related to infrastructure. In this work we provide a general overview of pollution in video sharing systems. We define the different kinds of existent pollution, their negative impact to users and system and possible strategies to minimize the problem.

scholarly journals Treating Children With Speech Sound Disorders: Development of a Tangible Artefact Prototype (Preprint)

2019 ◽  
Author(s):  
Joaquim Santos ◽  
Mário Vairinhos ◽  
Luis M T Jesus
Keyword(s):  
Serious Games ◽  
Qualitative Data ◽  
Speech Sound ◽  
Tangible Interaction ◽  
Tangible User Interface ◽  
Clear Pattern ◽  
Speech Sound Disorders ◽  
Ethnographic Approach ◽  
Different Types ◽  
Traditional Game

BACKGROUND A prototype of a tangible user interface (TUI) for a fishing game, which is intended to be used by children with speech sound disorders (SSD), speech and language therapists (SLTs), and kindergarten teachers and assistants (KTAs) and parents alike, has been developed and tested. OBJECTIVE The aim of this study was to answer the following question: How can TUIs be used as a tool to help in interventions for children with SSD? METHODS To obtain feedback and to ensure that the prototype was being developed according to the needs of the identified target users, an exploratory test was prepared and carried out. During this test using an ethnographic approach, an observation grid, a semistructured questionnaire, and interviews were used to gather data. A total of 4 different types of stakeholders (sample size of 10) tested the prototype: 2 SLTs, 2 KTAs, and 6 children. RESULTS The analysis of quantitative and qualitative data revealed that the prototype addresses the existing needs of SLTs and KTAs, and it revealed that 5 out of 6 (83%) children enjoyed the activity. Results also revealed a high replay value, with all children saying they would play more. CONCLUSIONS Serious games and tangible interaction for learning and problem solving serve both teachers and children, as children enjoy playing, and, through a playful approach, learning is facilitated. A clear pattern was observed: Children enjoyed playing, and numerous valid indicators showed the transposition of the traditional game into the TUI artefact was successful. The game is varied and rich enough to be attractive and fun. There is a clear need and interest in similar objects from SLTs and educators. However, the process should be even more iterative, with a multidisciplinary team, and all end users should be able to participate as co-designers.

scholarly journals The Composition and Relative Abundance of Fish Species in a Mangrove Creek in the Niger Delta, Nigeria, Based on Different Types of Gear

2011 ◽  
Vol 54 (3) ◽  
pp. 136-141
Author(s):  
Blessing Julius Oribhabor ◽  
Mfon Timothy Udo ◽  
Lawrence Etima ◽  
Ahmed Sardauna Adisa-Bolantab
Keyword(s):  
Relative Abundance ◽  
Fish Species ◽  
Niger Delta ◽  
Visual Observation ◽  
Species Assemblage ◽  
Benthic Species ◽  
Mangrove Creek ◽  
Different Types ◽  
Sarotherodon Melanotheron ◽  
Permanent Residents

The composition and relative abundance of fish species assemblage of a mangrove creek in the Niger Delta, Nigeria based on different types of gear was assessed at four stations between November 2004 and June 2006. The overall community structure was made up of 25 species of 16 families. Visual observation showed that tilapia species comprising of Sarotherodon melanotheron and Tilapia guineensis were the most dominant species. Samples from baited entrance traps indicated that S. melanotheron dominated T. guineensis. Samples from baited hook and line, and cast net showed dominance of P. elongatus followed by P. quadrifilis. (The baited hook and line is commonly used by the fishers because it is effective in catching diversity of species, except that it is unable to catch bottom feeders such as mullets and tilapia species). Funnel entrance trap had the highest species selectivity, catching only tilapia species. Cast net was more selective in species catch than baited hook and line, but it was effective in catching both pelagic and benthic species. Among the fish species, members of the families: Sciaenidae, Polynemidae, Ariidae, Monodactylidae and Cichlidae were permanent residents; Carangidae, Luthjanidae and Serranidae were temporary residents; while Elopidae, Gobiidae, Dasyatidae, Cynoglossidae, Sphyraenidae and Trichiuridae were rare species. Keywords: composition

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