LIVIVO - Search results -

Search results

Result 1 - 10 of total 24

Search options

Article: Deposition of >3.7 Ga clay-rich strata of the Mawrth Vallis Group, Mars, in lacustrine, alluvial, and aeolian environments.

Lowe, Donald R / Bishop, Janice L / Loizeau, Damien / Wray, James J / Beyer, Ross A

2019 Volume 132, Issue 1-2, Page(s) 17–30

Abstract: The presence of abundant phyllosilicate minerals in Noachian (>3.7 Ga) rocks on Mars has been taken as evidence that liquid water was stable at or near the surface early in martian history. This study investigates some of these clay-rich strata exposed ... ...

Abstract	The presence of abundant phyllosilicate minerals in Noachian (>3.7 Ga) rocks on Mars has been taken as evidence that liquid water was stable at or near the surface early in martian history. This study investigates some of these clay-rich strata exposed in crater rim and inverted terrain settings in the Mawrth Vallis region of Mars. In Muara crater the 200-m-thick, clay-rich Mawrth Vallis Group (MVG) is subdivided into five informal units numbered 1 (base) to 5 (top). Unit 1 consists of interbedded sedimentary and volcanic or volcaniclastic units showing weak Fe/Mg-smectite alteration deposited in a range of subaerial depositional settings. Above a major unconformity eroded on Unit 1, the dark-toned sediments of Unit 2 and lower Unit 3 are inferred to represent mainly wind-blown sand. These are widely interlayered with and draped by thin layers of light-toned sediment representing fine suspended-load aeolian silt and clay. These sediments show extensive Fe/Mg-smectite alteration, probably reflecting subaerial weathering. Upper Unit 3 and units 4 and 5 are composed of well-layered, fine-grained sediment dominated by Al-phyllosilicates, kaolinite, and hydrated silica. Deposition occurred in a large lake or arm of a martian sea. In the inverted terrain 100 km to the NE, Unit 4 shows very young slope failures suggesting that the clay-rich sediments today retain a significant component of water ice. The MVG provides evidence for the presence of large, persistent standing bodies of water on early Mars as well as a complex association of flanking shoreline, alluvial, and aeolian systems. Some of the clays, especially the Fe/Mg smectites in upper units 1 and 2 appear to have formed through subaerial weathering whereas the aluminosilicates, kaolinite, and hydrated silica of units 3, 4, and 5 formed mainly through alteration of fine sediment in subaqueous environments.
Language	English
Publishing date	2019-05-02
Publishing country	United States
Document type	Journal Article
ZDB-ID	1351-1
ISSN	0016-7606
ISSN	0016-7606
DOI	10.1130/b35185.1
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Bonn / Germany

Z 4' 46/148: Show issues

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾
- See ZB MED holdings
- Order with fees

Article: Multiple mineral horizons in layered outcrops at Mawrth Vallis, Mars, signify changing geochemical environments on early Mars.

Bishop, Janice L / Gross, Christoph / Danielsen, Jacob / Parente, Mario / Murchie, Scott L / Horgan, Briony / Wray, James J / Viviano, Christina / Seelos, Frank P

Icarus

2020 Volume 341

Abstract: Refined calibrations of CRISM images are enabling identification of smaller deposits of unique aqueous materials on Mars that reveal changing environmental conditions at the region surrounding Mawrth Vallis. Through characterization of these clay-sulfate ...

Abstract	Refined calibrations of CRISM images are enabling identification of smaller deposits of unique aqueous materials on Mars that reveal changing environmental conditions at the region surrounding Mawrth Vallis. Through characterization of these clay-sulfate assemblages and their association with the layered, phyllosilicate units of this region, more details of the aqueous geochemical history can be gleaned. A stratigraphy including five distinct mineral horizons is mapped using compositional data from CRISM over CTX and HRSC imagery across 100s of km and from CRISM over HiRISE imagery across 100s of meters. Transitions in mineralogic units were characterized using visible/near-infrared (VNIR) spectral properties and surface morphology. We identified and characterized complex "doublet" type spectral signatures with two bands between 2.2 and 2.3 μm at one stratigraphic horizon. Based on comparisons with terrestrial sites, the spectral "doublet" unit described here may reflect the remnants of a salty, evaporative period that existed on Mars during the transition from formation of Fe-rich phyllosilicates to Al-rich phyllosilicates. Layered outcrops observed at Mawrth Vallis are thicker than in other altered regions of Mars, but may represent processes that were more widespread in wet regions of the planet during its early history. The aqueous geochemical environments supporting the outcrops observed here include: (i) the formation of Fe
Language	English
Publishing date	2020-01-17
Publishing country	United States
Document type	Journal Article
ISSN	0019-1035
ISSN	0019-1035
DOI	10.1016/j.icarus.2020.113634
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article: Software agents in molecular computational biology.

Keele, John W / Wray, James E

Briefings in bioinformatics

2006 Volume 6, Issue 4, Page(s) 370–379

Abstract: Progress made in applying agent systems to molecular computational biology is reviewed and strategies by which to exploit agent technology to greater advantage are investigated. Communities of software agents could play an important role in helping ... ...

Abstract	Progress made in applying agent systems to molecular computational biology is reviewed and strategies by which to exploit agent technology to greater advantage are investigated. Communities of software agents could play an important role in helping genome scientists design reagents for future research. The advent of genome sequencing in cattle and swine increases the complexity of data analysis required to conduct research in livestock genomics. Databases are always expanding and semantic differences among data are common. Agent platforms have been developed to deal with generic issues such as agent communication, life cycle management and advertisement of services (white and yellow pages). This frees computational biologists from the drudgery of having to re-invent the wheel on these common chores, giving them more time to focus on biology and bioinformatics. Agent platforms that comply with the Foundation for Intelligent Physical Agents (FIPA) standards are able to interoperate. In other words, agents developed on different platforms can communicate and cooperate with one another if domain-specific higher-level communication protocol details are agreed upon between different agent developers. Many software agent platforms are peer-to-peer, which means that even if some of the agents and data repositories are temporarily unavailable, a subset of the goals of the system can still be met. Past use of software agents in bioinformatics indicates that an agent approach should prove fruitful. Examination of current problems in bioinformatics indicates that existing agent platforms should be adaptable to novel situations.
MeSH term(s)	Algorithms ; Animals ; Artificial Intelligence ; Chromosome Mapping/methods ; Computational Biology/methods ; Genomics/methods ; Molecular Biology/methods ; Sequence Analysis/methods ; Software ; User-Computer Interface
Language	English
Publishing date	2006-01-05
Publishing country	England
Document type	Journal Article
ZDB-ID	2068142-2
ISSN	1467-5463
ISSN	1467-5463
DOI	10.1093/bib/6.4.370
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 6262: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: A record of igneous evolution in Elysium, a major martian volcanic province.

Susko, David / Karunatillake, Suniti / Kodikara, Gayantha / Skok, J R / Wray, James / Heldmann, Jennifer / Cousin, Agnes / Judice, Taylor

Scientific reports

2017 Volume 7, Page(s) 43177

Abstract: A major knowledge gap exists on how eruptive compositions of a single martian volcanic province change over time. Here we seek to fill that gap by assessing the compositional evolution of Elysium, a major martian volcanic province. A unique geochemical ... ...

Abstract	A major knowledge gap exists on how eruptive compositions of a single martian volcanic province change over time. Here we seek to fill that gap by assessing the compositional evolution of Elysium, a major martian volcanic province. A unique geochemical signature overlaps with the southeastern flows of this volcano, which provides the context for this study of variability of martian magmatism. The southeastern lava fields of Elysium Planitia show distinct chemistry in the shallow subsurface (down to several decimeters) relative to the rest of the martian mid-to-low latitudes (average crust) and flows in northwest Elysium. By impact crater counting chronology we estimated the age of the southeastern province to be 0.85 ± 0.08 Ga younger than the northwestern fields. This study of the geochemical and temporal differences between the NW and SE Elysium lava fields is the first to demonstrate compositional variation within a single volcanic province on Mars. We interpret the geochemical and temporal differences between the SE and NW lava fields to be consistent with primary magmatic processes, such as mantle heterogeneity or change in depth of melt formation within the martian mantle due to crustal loading.
Language	English
Publishing date	2017--24
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/srep43177
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Article ; Online: Exposed subsurface ice sheets in the Martian mid-latitudes.

Dundas, Colin M / Bramson, Ali M / Ojha, Lujendra / Wray, James J / Mellon, Michael T / Byrne, Shane / McEwen, Alfred S / Putzig, Nathaniel E / Viola, Donna / Sutton, Sarah / Clark, Erin / Holt, John W

Science (New York, N.Y.)

2018 Volume 359, Issue 6372, Page(s) 199–201

Abstract: Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion in these regions creates scarps that expose the internal structure of the mantle. We investigated eight of these locations and found that they expose deposits ... ...

Abstract	Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion in these regions creates scarps that expose the internal structure of the mantle. We investigated eight of these locations and found that they expose deposits of water ice that can be >100 meters thick, extending downward from depths as shallow as 1 to 2 meters below the surface. The scarps are actively retreating because of sublimation of the exposed water ice. The ice deposits likely originated as snowfall during Mars' high-obliquity periods and have now compacted into massive, fractured, and layered ice. We expect the vertical structure of Martian ice-rich deposits to preserve a record of ice deposition and past climate.
MeSH term(s)	Extraterrestrial Environment ; Ice Cover ; Mars
Language	English
Publishing date	2018-01-11
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.aao1619
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 27: Show issues			Location: Je nach Verfügbarkeit (siehe Angabe bei Bestand) bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular Jg. 1995 - 2021: Lesesall (1.OG) ab Jg. 2022: Lesesaal (EG)
Zs.MG 77: Show issues

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Xeropreservation of functionalized lipid biomarkers in hyperarid soils in the Atacama Desert.

Wilhelm, Mary Beth / Davila, Alfonso F / Eigenbrode, Jennifer L / Parenteau, Mary N / Jahnke, Linda L / Liu, Xiao-Lei / Summons, Roger E / Wray, James J / Stamos, Brian N / O'Reilly, Shane S / Williams, Amy

Organic geochemistry

2017 Volume 103, Page(s) 97–104

Abstract: Our understanding of long-term organic matter preservation comes mostly from studies in aquatic systems. In contrast, taphonomic processes in extremely dry environments are relatively understudied and are poorly understood. We investigated the ... ...

Abstract	Our understanding of long-term organic matter preservation comes mostly from studies in aquatic systems. In contrast, taphonomic processes in extremely dry environments are relatively understudied and are poorly understood. We investigated the accumulation and preservation of lipid biomarkers in hyperarid soils in the Yungay region of the Atacama Desert. Lipids from seven soil horizons in a 2.5 m vertical profile were extracted and analyzed using GC-MS and LC-MS. Diagnostic functionalized lipids and geolipids were detected and increased in abundance and diversity with depth. Deeper clay units contain fossil organic matter (radiocarbon dead) that has been protected from rainwater since the onset of hyperaridity. We show that these clay units contain lipids in an excellent state of structural preservation with functional groups and unsaturated bonds in carbon chains. This indicates that minimal degradation of lipids has occurred in these soils since the time of their deposition between >40,000 and 2 million years ago. The exceptional structural preservation of biomarkers is likely due to the long-term hyperaridity that has minimized microbial and enzymatic activity, a taphonomic process we term xeropreservation (i.e. preservation by drying). The degree of biomarker preservation allowed us to reconstruct major changes in ecology in the Yungay region that reflect a shift in hydrological regime from wet to dry since the early Quaternary. Our results suggest that hyperarid environments, which comprise 7.5% of the continental landmass, could represent a rich and relatively unexplored source of paleobiological information on Earth.
Language	English
Publishing date	2017-01
Publishing country	England
Document type	Journal Article
ISSN	0146-6380
ISSN	0146-6380
DOI	10.1016/j.orggeochem.2016.10.015
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Constraints on the Metabolic Activity of Microorganisms in Atacama Surface Soils Inferred from Refractory Biomarkers: Implications for Martian Habitability and Biomarker Detection.

Wilhelm, Mary Beth / Davila, Alfonso F / Parenteau, Mary N / Jahnke, Linda L / Abate, Mastewal / Cooper, George / Kelly, Erin Taylor / Parro García, Victor / Villadangos, Miriam G / Blanco, Yolanda / Glass, Brian / Wray, James J / Eigenbrode, Jennifer L / Summons, Roger E / Warren-Rhodes, Kimberly

Astrobiology

2018 Volume 18, Issue 7, Page(s) 955–966

Abstract: Dryness is one of the main environmental challenges to microbial survival. Understanding the threshold of microbial tolerance to extreme dryness is relevant to better constrain the environmental limits of life on Earth and critically evaluate long-term ... ...

Abstract	Dryness is one of the main environmental challenges to microbial survival. Understanding the threshold of microbial tolerance to extreme dryness is relevant to better constrain the environmental limits of life on Earth and critically evaluate long-term habitability models of Mars. Biomolecular proxies for microbial adaptation and growth were measured in Mars-like hyperarid surface soils in the Atacama Desert that experience only a few millimeters of precipitation per decade, and in biologically active soils a few hundred kilometers away that experience two- to fivefold more precipitation. Diversity and abundance of lipids and other biomolecules decreased with increasing dryness. Cyclopropane fatty acids (CFAs), which are indicative of adaptive response to environmental stress and growth in bacteria, were only detected in the wetter surface soils. The ratio of trans to cis isomers of an unsaturated fatty acid, another bacterial stress indicator, decreased with increasingly dry conditions. Aspartic acid racemization ratios increased from 0.01 in the wetter soils to 0.1 in the driest soils, which is indicative of racemization rates comparable to de novo biosynthesis over long timescales (∼10,000 years). The content and integrity of stress proteins profiled by immunoassays were additional indicators that biomass in the driest soils is not recycled at significant levels. Together, our results point to minimal or no in situ microbial growth in the driest surface soils of the Atacama, and any metabolic activity is likely to be basal for cellular repair and maintenance only. Our data add to a growing body of evidence that the driest Atacama surface soils represent a threshold for long-term habitability (i.e., growth and reproduction). These results place constraints on the potential for extant life on the surface of Mars, which is 100-1000 times drier than the driest regions in the Atacama. Key Words: Atacama Desert-Dryness-Growth-Habitability-Biomarker-Mars. Astrobiology 18, 955-966.
MeSH term(s)	Bacteria/isolation & purification ; Bacteria/metabolism ; Biomarkers/analysis ; Biomarkers/metabolism ; Biomass ; Chile ; Desert Climate ; Exobiology/methods ; Extraterrestrial Environment ; Mars ; Soil Microbiology
Chemical Substances	Biomarkers
Language	English
Publishing date	2018-07-22
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2047736-3
ISSN	1557-8070 ; 1531-1074
ISSN (online)	1557-8070
ISSN	1531-1074
DOI	10.1089/ast.2017.1705
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Book: The color atlas of galaxies

Wray, James D

1988

Author's details	James D. Wray
Language	English
Size	XI, 189 S, überwiegend Ill, 31 cm
Publisher	Cambridge Univ. Press
Publishing place	Cambridge u.a.
Document type	Book
ISBN	0521322367 ; 9780521322362
Database	Former special subject collection: coastal and deep sea fishing

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Seasonal flows on warm Martian slopes.

McEwen, Alfred S / Ojha, Lujendra / Dundas, Colin M / Mattson, Sarah S / Byrne, Shane / Wray, James J / Cull, Selby C / Murchie, Scott L / Thomas, Nicolas / Gulick, Virginia C

Science (New York, N.Y.)

2011 Volume 333, Issue 6043, Page(s) 740–743

Abstract: Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from ...

Abstract	Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25° to 40°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48°S to 32°S latitudes favoring equator-facing slopes, which are times and places with peak surface temperatures from ~250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.
MeSH term(s)	Extraterrestrial Environment ; Mars ; Salts ; Seasons ; Spacecraft ; Temperature ; Water
Chemical Substances	Salts ; brine ; Water (059QF0KO0R)
Language	English
Publishing date	2011-08-05
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.1204816
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 27: Show issues			Location: Je nach Verfügbarkeit (siehe Angabe bei Bestand) bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular Jg. 1995 - 2021: Lesesall (1.OG) ab Jg. 2022: Lesesaal (EG)
Zs.MG 77: Show issues

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article: Seasonal Flows on Warm Martian Slopes

McEwen, Alfred S / Byrne, Shane / Cull, Selby C / Dundas, Colin M / Gulick, Virginia C / Mattson, Sarah S / Murchie, Scott L / Ojha, Lujendra / Thomas, Nicolas / Wray, James J

Science. 2011 Aug. 5, v. 333, no. 6043

2011

Abstract	Water probably flowed across ancient Mars, but whether it ever exists as a liquid on the surface today remains debatable. Recurring slope lineae (RSL) are narrow (0.5 to 5 meters), relatively dark markings on steep (25Â° to 40Â°) slopes; repeat images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment show them to appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in some rare locations. RSL appear and lengthen in the late southern spring and summer from 48Â°S to 32Â°S latitudes favoring equator-facing slopes, which are times and places with peak surface temperatures from approximately 250 to 300 kelvin. Liquid brines near the surface might explain this activity, but the exact mechanism and source of water are not understood.
Keywords	bedrock ; cold season ; image analysis ; latitude ; spring ; summer ; surface temperature
Language	English
Dates of publication	2011-0805
Size	p. 740-743.
Publishing place	American Association for the Advancement of Science
Document type	Article
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.1204816
Database	NAL-Catalogue (AGRICOLA)

In stock of ZB MED Bonn / Germany

Z 4' 46/137: Show issues
+ C 27: Show issues
Z50.00 SC01: Show issues
Z 8.9: Show issues

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾
- See ZB MED holdings
- Order with fees

To top

More links

Kategorien

In stock of ZB MED Bonn / Germany

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

Order via subito

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Bonn / Germany

Order via subito

Inter-library loan at ZB MED