Oxygen isotope composition of the primitive Achondrites

Primitive achondrites provide a record of the earliest stages of asteroidal melting. A detailed study of their oxygen isotope variation shows that these meteorites retain significant levels of primary oxygen isotope heterogeneity

Book Review: Spies, Lies, and Algorithms: The History and Future of American Intelligence

The security environment is entering a new threat landscape; one that must be fought in both the physical and virtual world. The seemingly instantaneous progress of digitization and the cyberspace domain threatens to destabilize traditional warfare strategies and intelligence norms. Amy Zegart, an American academic and leading national security expert, outlines the history and future of American intelligence with a specific emphasis on emerging cyber threats in the digital age. In Spies, Lies, and Algorithms, Zegart explains the roles of technological breakthroughs in a world of big data by chronicling the history of intelligence education and organizational reform, the evolution of American intelligence, what intelligence is and is not, the challenges of intelligence and counterintelligence analysis and covert operations, legislative responsibilities, the upsurge of non-state actors, and the advancement of cyber threats

What does the CM chondrite mineralogic alteration index really mean?

Accepted versio

Volatile depletion: Constraints from differentiated meteorites

Accepted versio

Bias correction factors for near-Earth asteroids

Knowledge of the population size and physical characteristics (albedo, size, and rotation rate) of near-Earth asteroids (NEA's) is biased by observational selection effects which are functions of the population's intrinsic properties and the size of the telescope, detector sensitivity, and search strategy used. The NEA population is modeled in terms of orbital and physical elements: a, e, i, omega, Omega, M, albedo, and diameter, and an asteroid search program is simulated using actual telescope pointings of right ascension, declination, date, and time. The position of each object in the model population is calculated at the date and time of each telescope pointing. The program tests to see if that object is within the field of view (FOV = 8.75 degrees) of the telescope and above the limiting magnitude (V = +1.65) of the film. The effect of the starting population on the outcome of the simulation's discoveries is compared to the actual discoveries in order to define a most probable starting population

The effect of composition and zoning on infra-red spectra of the Martian silicate minerals

http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2199.pd

Correlated modal mineralogy, aqueous alteration and oxygen isotope composition of CM Chondrites

In this study we move beyond defining alteration sequences in CM chondrites towards understanding the relationship between modal mineralogy, the extent of aqueous alteration and O-isotope compositions

A geochemical study of the winonaites: Evidence for limited partial melting and constraints on the precursor composition

The winonaites are primitive achondrites which are associated with the IAB iron meteorites. Textural evidence implies heating to at least the Fe, Ni–FeS cotectic, but previous geochemical studies are ambiguous about the extent of silicate melting in these samples. Oxygen isotope evidence indicates that the precursor material may be related to the carbonaceous chondrites. Here we analysed a suite of winonaites for modal mineralogy and bulk major- and trace-element chemistry in order to assess the extent of thermal processing as well as constrain the precursor composition of the winonaite-IAB parent asteroid. Modal mineralogy and geochemical data are presented for eight winonaites. Textural analysis reveals that, for our sub-set of samples, all except the most primitive winonaite (Northwest Africa 1463) reached the Fe, Ni–FeS cotectic. However, only one (Tierra Blanca) shows geochemical evidence for silicate melting processes. Tierra Blanca is interpreted as a residue of small-degree silicate melting. Our sample of Winona shows geochemical evidence for extensive terrestrial weathering. All other winonaites studied here (Fortuna, Queen Alexander Range 94535, Hammadah al Hamra 193, Pontlyfni and NWA 1463) have chondritic major-element ratios and flat CI-normalised bulk rare-earth element patterns, suggesting that most of the winonaites did not reach the silicate melting temperature. The majority of winonaites were therefore heated to a narrow temperature range of between ∼1220 (the Fe, Ni–FeS cotectic temperature) and ∼1370 K (the basaltic partial melting temperature). Silicate inclusions in the IAB irons demonstrate partial melting did occur in some parts of the parent body (Ruzicka and Hutson, 2010), thereby implying heterogeneous heat distribution within this asteroid. Together, this indicates that melting was the result of internal heating by short-lived radionuclides. The brecciated nature of the winonaites suggests that the parent body was later disrupted by a catastrophic impact, which allowed the preservation of the largely unmelted winonaites. Despite major-element similarities to both ordinary and enstatite chondrites, trace-element analysis suggests the winonaite parent body had a carbonaceous chondrite-like precursor composition. The parent body of the winonaites was volatile-depleted relative to CI, but enriched compared to the other carbonaceous classes. The closest match are the CM chondrites; however, the specific precursor is not sampled in current meteorite collections

Das „gläserne Schlachtfeld“ als soziotechnologisches Leitbild der modernen US-amerikanischen Kriegführung

The Information Revolution has leveraged the attention which the academic discourse is paying to the impacts of information and communication technologies, although aspects of how to conceptualize these impacts theoretically are insufficient. Focusing on the role of IT during the rearmament of the US-military since the end of the Cold War a neogramscian perspective on the genesis and diffusion of IT as “political project” is outlined. IT gives a new model of warfare and contributes to the significant consent which the rearmament of the US-military has gained among US-citizens