467 research outputs found
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Phase Equilibria Modeling of Low-Grade Metamorphic Martian Rocks
We report on modeling low-grade (up to 300 °C) metamorphic reactions with Martian starting materials
Linking the Quark Meson Model with QCD at High Temperature
We model the transition of a system of quarks and gluons at high energies to
a system of quarks and mesons at low energies in a consistent renormalization
group approach. Flow equations interpolate between the physics of the
high-temperature degrees of freedom and the low-temperature dynamics at a scale
of 1 GeV. We also discuss the dependence of the equation of state on baryon
density and compare our results with recent lattice gauge simulations.Comment: 11 pages, 4 figures additional discussion of the second order phase
transitio
3D Surface Measurement for Medical ApplicationâTechnical Comparison of Two Established Industrial Surface Scanning Systems
In 3D mapping of flexible surfaces (e.g. human faces) measurement errors due to movement or positioning occur. Aggravated by equipment- or researcher-caused mistakes considerable deviations can result. Therefore first the appliances' precision handling and reliability in clinical environment must be established. Aim of this study was to investigate accuracy and precision of two contact-free 3D measurement systems (white light vs. laser). Standard specimens of known diameter for sphere deviation, touch deviation and plane deviation were tested. Both systems are appropriate for medical application acquiring solid data (<mm). The more complex white-light system shows better accuracy at 0.2s measuring time. The laser system is superior concerning robustness, while accuracy is poorer and input time (1.5-2.5s) longer. Due to the clinical demand the white-light system is superior in a laboratory environment, while the laser system is easier to handle under non-laboratory condition
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The Apollo Virtual Microscope Collection: Lunar Mineralogy and Petrology of Apollo 11, 12, 14, 15 and 16 Rocks
We report on the new Virtual Microscopes on Apollo 16 lunar samples in our Apollo Virtual Microscope collection
Phase Equilibria Modeling of Low-grade Metamorphic Martian Rocks
Hydrous phases have been identified to be a significant component of martian mineralogy. Particularly prehnite, zeolites, and serpentine are evidence for lowâgrade metamorphic reactions at elevated temperatures in mafic and ultramafic protoliths. Their presence suggests that at least part of the martian crust is sufficiently hydrated for lowâgrade metamorphic reactions to occur. A detailed analysis of changes in mineralogy with variations in fluid content and composition along possible martian geotherms can contribute to determine the conditions required for subsurface hydrous alteration, fluid availability and rock properties in the martian crust. In this study, we use phase equilibria models to explore lowâgrade metamorphic reactions covering a pressureâtemperature range of 0â0.5 GPa and 150â450 °C for several martian protolith compositions and varying fluid content. Our models replicate the detected lowâgrade metamorphic/hydrothermal mineral phases like prehnite, chlorite, analcime, unspecified zeolites, and serpentine. Our results also suggest that actinolite should be a part of lowerâgrade metamorphic assemblages, but actinolite may not be detected in reflectance spectra for several reasons. By gradually increasing the water content in the modeled whole rock composition, we can estimate the amount of water required to precipitate lowâgrade metamorphic phases. Mineralogical constraints do not necessarily require an elevated geothermal gradient for the formation of prehnite. However, restricted crater excavation depths even for large impact craters are not likely sampling prehnite along colder gradients, either suggesting a geotherm of ~ 20 °C/km in the Noachian or an additional heat source such as hydrothermal or magmatic activity
A review of volatiles in the Martian interior
Multiple observations from missions to Mars have revealed compelling evidence for a volatile-rich Martian crust. A leading theory contends that eruption of basaltic magmas was the ultimate mechanism of transfer of volatiles from the mantle toward the surface after an initial outgassing related to the crystallization of a magma ocean. However, the concentrations of volatile species in ascending magmas and in their mantle source regions are highly uncertain. This work and this special issue of Meteoritics & Planetary Science summarize the key findings of the workshop on Volatiles in the Martian Interior (Nov. 3â4, 2014), the primary open questions related to volatiles in Martian magmas and their source regions, and the suggestions of the community at the workshop to address these open questions
In situ measurement of atmospheric krypton and xenon on Mars with Mars Science Laboratory
Mars Science Laboratory's Sample Analysis at Mars (SAM) investigation has measured all of the stable isotopes of the heavy noble gases krypton and xenon in the martian atmosphere, in situ, from the Curiosity Rover at Gale Crater, Mars. Previous knowledge of martian atmospheric krypton and xenon isotope ratios has been based upon a combination of the Viking mission's krypton and xenon detections and measurements of noble gas isotope ratios in martian meteorites. However, the meteorite measurements reveal an impure mixture of atmospheric, mantle, and spallation contributions. The xenon and krypton isotopic measurements reported here include the complete set of stable isotopes, unmeasured by Viking. The new results generally agree with Mars meteorite measurements but also provide a unique opportunity to identify various non-atmospheric heavy noble gas components in the meteorites. Kr isotopic measurements define a solar-like atmospheric composition, but deviating from the solar wind pattern at 80Kr and 82Kr in a manner consistent with contributions originating from neutron capture in Br. The Xe measurements suggest an intriguing possibility that isotopes lighter than 132Xe have been enriched to varying degrees by spallation and neutron capture products degassed to the atmosphere from the regolith, and a model is constructed to explore this possibility. Such a spallation component, however, is not apparent in atmospheric Xe trapped in the glassy phases of martian meteorites
Lippen-Kiefer-Gaumen-Spalten: Individuelle Analyse der Lippenspalte durch 3-D-Lasertopometrie
Zusammenfassung: Hintergrund: Mit Gipsmodellen und Fotografien ist die dreidimensionale Analyse einer Lippen-Kiefer-Gaumen-Spalte meist nur unzureichend möglich. Ziel der vorliegenden Studie war es daher, die 3-D-Lasertopometrie auf ihre Anwendbarkeit zur dreidimensionalen Weichgewebserfassung bei Patienten mit Lippen-Kiefer-Gaumen-Spalten zu testen. Patienten und Methode: Bei 20âŻPatienten (3-35âŻJahre), die eine einseitige, nicht operierte Lippen-, Lippen-Kiefer- oder Lippen-Kiefer-Gaumen-Spalte aufwiesen, wurde mit einem 3-D-Laserscanner die GesichtsoberflĂ€che prĂ€- und postoperativ dreidimensional erfasst. Die dabei erzeugten digitalen DatensĂ€tze wurden in einer virtuellen Umgebung metrisch analysiert und anhand von Quotienten gröĂenunabhĂ€ngig wiedergegeben. Sie dienten der Auswahl der Operationstechnik und der Beurteilung des Operationsergebnisses. Ergebnisse: Mit dem 3-D-Laserscanner wurden 3-D-OberflĂ€chen guter QualitĂ€t erstellt, die sich im Millimeterbereich ausmessen lieĂen. Die dreidimensionale Spaltmorphologie konnte in den DatensĂ€tzen reproduzierbar mit Landmarks versehen und vermessen werden. Auch die postoperative Symmetrie lieĂ sich so kontrollieren und objektivieren. Als nachteilig erwiesen sich die relativ lange Messzeit und die Notwendigkeit zur Kombination mehrerer Ansichten. Schlussfolgerung: Das vorgestellte 3-D-Laserverfahren ermöglicht eine prĂ€zise dreidimensionale Weichteilanalyse der Lippen- und Nasenregion bei Spaltpatienten. Es eignet sich jedoch nur bedingt fĂŒr lebhafte SĂ€uglinge und unkooperative Patiente
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Mineral Surface and Fluid Chemistry in Nakhlite Analog Water-Rock Reactions
We report on experiments with Mars analog materials under diagenetic conditions and find characteristic chemical surface changes in correspondence with the fluid conditions
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