Entscheidungstheoretische Grundlagen der Stochastischen Optimierung

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Fragmentary Solar System History

The objective of this research is an improved understanding of the early solar system environment and of the processes involved in the nebula and in the evolution of solid bodies. We present results of our studies on the isotopic signatures in selected primitive solar system objects and on the evaluation of the cosmic ray records and of inferred collisional events. Furthermore, we report data of trapped martian atmospheric gases in meteorites and the inferred early evolution of Mars' atmosphere

Martian mantle signatures in Yamato nakhlites

We report nitrogen and heavy noble gas isotopic abundances in the Yamato nakhlites Y000593 and Y000749 and infer isotopic signatures for the magma source region in Mars. The nitrogen signature 15N=13±1 appears in broad plateau releases of both nakhlites and also has previously been observed in Nakhla and in Chassigny. This signature differs from the primitive indigenous nitrogen signature (15N=30) and, strikingly, from nitrogen in the modern Martian atmosphere. It demonstrates that exchanges between the solid planet and its modern atmosphere have been very limited. The xenon isotopic records support this conclusion. In nakhlite Y000749 radiogenic 129Xe is observed in one temperature fraction, while a five times larger component is observed in several steps of Y000593. The lack of an association with fission Xe or with indigenous Xe from the mantle source region suggests a crustal source. A crustal storage of the extinct 129I was previously invoked to account for radiogenic 129Xe in the Martian atmosphere. Fission Xe components due to extinct 244Pu were identified in both nakhlites. These records show that the magma source region had assimilated and retained fission gas since the early differentiation of Mars. The measured concentrations of 40Ar exceed the amounts produced from the decay of 40K in 1.3Ga and document that the magma inherited some radiogenic 40Ar, together with fission gas. CRE ages based on spallation 15Nc and 38Ar are consistent with a reported 81Kr-83Kr age and CRE ages for other nakhlites, confirming identical ejection ages for all nakhlites

The glaciation of Serra de Queixa-Invernadoiro and Serra do Gerês-Xurés, NW Iberia. A critical review and a cosmogenic nuclide (10Be and 21 Ne) chronology.

[Abstract]The Serras of Queixa-Invernadoiro and Gerês-Xurés in the NW of the Iberian Peninsula are two small mountain massifs located at low altitude that were glaciated in the Pleistocene. The prevailing granitic lithology was a problem for mapping glacial forms (in many cases interpreted as banal granite forms) and for the identification of the tills (misunderstood as remains of regolith). A combination of geomorphological techniques (genetic mapping of granite forms and deposits), the micromorphological study of till thin sections and the morphoscopy of quartz grains at the SEM enabled to establish a model of the geomorphological evolution complemented with the chronology by cosmogenic nuclides (21Ne and 10Be) of both glacial systems. The obtained results represent the glacial evolution of the area from circa 250 ka B.P

Single grain (U-Th)/He ages from phosphates in Acapulco meteorite and implications for thermal history

The cooling history of the Acapulco meteorite for >400°C is well established using various chronometers suggesting extremely fast cooling (>1000°C/Ma). In contrast, the thermal history for low temperatures (<400°C) is poorly understood because of large uncertainties in the chronometers applicable to this temperature range. To better constrain the cooling history for the low-temperature range, we applied (U–Th)/He dating techniques to individual phosphate grains. One whitlockite and 11 apatite grains yielded (U–Th)/He ages ranging from 1272±22 (1σ, analytical error only) Ma to 4584±51 Ma, with tight clustering at ∼4.55 Ga. The weighted mean of the five oldest ages (4538±32 Ma, 1σ uncertainty including systematic error) is suggested to be the minimum age representing primary cooling of the Acapulco body passing through ∼120°C. Although it is impossible to precisely quantify the effects of energetic α particle ejection from the outermost ∼20 μm of the phosphates, petrographic evidence suggests that most dated samples are fragments likely derived from the interior of larger grains, thus greatly reducing this source of error. Indeed the five oldest samples cannot have suffered substantial ejection since the uncorrected ages are identical with the crystallization age of the Acapulco meteorite. The new (U–Th)/He data suggest rapid cooling of Acapulco down to ∼120°C. This evidence suggests that the younger ^(40)Ar/^(39)Ar age (4507±9 (1σ) Ma) obtained from Acapulco plagioclase, which should reflect cooling through ∼300°C, is spuriously young due to systematic errors (i.e., decay constants and/or standard data) in the ^(40)Ar/^(39)Ar method, as suggested by comparison between high-precision ^(40)Ar/^(39)Ar and U/Pb ages for terrestrial volcanic rocks. The scattered He age distribution <4.0 Ga implies very heterogeneous thermal disturbances after the primary cooling of the body

New data on the chronology of Pleistocene glaciation in the NW of the Iberian Peninsula

[Abstract] The age of glacial features subaerial exposition: polished surfaces and morainic blocks using cosmogenic isotopes in granite substrate areas of the NW Iberian Peninsula have permitted to distinguish several glacier phases in which until the moment was considered a single one attributed to the Würm. The resulting data are roughly consistent with the previous geomorphologic model for the area and improves the chronological accuracy and the understanding of the Pleistocene glacial dynamics in the NW Spain. The proposed sequence of events also fits very well with previous palaeoclimate reconstructions for the same period at world scale

Nitrogen isotopic signatures in agglutinates from breccia 79035

Agglutinates in the size range 125-175 microns from regolith breccia 79035 are substantially depleted in N compared with bulk 79035. Isotopically, agglutinate N closely resembles that found previously in ilmenite separates. The minimum (delta)N-15 value found during stepwise pyrolysis of agglutinates is significantly heavier than that observed for bulk 79035. The major host phase for trapped N in 79035, and the host phase of the lightest isotopic component(s), remain unidentified

Regolith history of the aubritic meteorite parent body revealed by neutron capture effects on Sm and Gd isotopes

Enstatite achondrites (aubrites) when compared to other stone meteorites have unusually long cosmic-ray exposure (CRE) ages. We report here the 150Sm/149Sm and 158Gd/157Gd ratios in six different structural phases, i.e., light and dark (shocked) grains and in matrix materials of Pesyanoe, in three different fragments from Pena Blanca Spring, and in one from Norton County, Shallowater, and Khor Temiki, to investigate the regolith history on the aubrite parent body. The results from phases components of Pesyanoe confirm earlier reported evidence for regolith irradiation of several aubrites. The inferred neutron fluences for six Pesyanoe separates vary between (2.13 and 2.82) × 1016 n cm-2. The fluences also significantly exceed those expected from cosmic-ray irradiation during transit to Earth and approach those observed in the lunar regolith. These observations confirm that the brecciated Pesyanoe meteorite, which contains solar wind (SW) gases only in dark phases, was processed in a regolith and that structural phases were differentially irradiated before compaction. On the other hand, in some aubrites (Mt. Egerton, Shallowater, Pena Blanca Spring, Norton County) neutron capture effects may entirely be due to space irradiation

Implementing measurement-based care (iMBC) for depression in community mental health: a dynamic cluster randomized trial study protocol

BACKGROUND: Measurement-based care is an evidence-based practice for depression that efficiently identifies treatment non-responders and those who might otherwise deteriorate [1]. However, measurement-based care is underutilized in community mental health with data suggesting fewer than 20 % of behavioral health providers using this practice to inform treatment. It remains unclear whether standardized or tailored approaches to implementation are needed to optimize measurement-based care fidelity and penetration. Moreover, there is some suggestion that prospectively tailored interventions that are designed to fit the dynamic context may optimize public health impact, though no randomized trials have yet tested this notion [2]. This study will address the following three aims: (1) To compare the effect of standardized versus tailored MBC implementation on clinician-level and client-level outcomes; (2) To identify contextual mediators of MBC fidelity; and (3) To explore the impact of MBC fidelity on client outcomes. METHODS/DESIGN: This study is a dynamic cluster randomized trial of standardized versus tailored measurement-based care implementation in Centerstone, the largest provider of community-based mental health services in the USA. This prospective, mixed methods implementation-effectiveness hybrid design allows for evaluation of the two conditions on both clinician-level (e.g., MBC fidelity) and client-level (depression symptom change) outcomes. Central to this investigation is the focus on identifying contextual factors (e.g., attitudes, resources, process, etc.) that mediate MBC fidelity and optimize client outcomes. DISCUSSION: This study will contribute generalizable and practical strategies for implementing systematic symptom monitoring to inform and enhance behavioral healthcare. TRIAL REGISTRATION: Clinicaltrials.gov NCT02266134