Evaluation of star gyro torquing final report

Electrostatic gyroscope torquin

Impact of forest drought response on land-atmosphere interactions

The Amazon forests are one of the largest ecosystem carbon pools on Earth. Although more frequent and prolonged droughts have been predicted under future climate change there, the vulnerability of Amazon forests to drought has yet remained largely uncertain, as most land surface models failed to capture the vegetation responses to drought. In this study, the ability of the state-of-the-art land surface model JSBACH to simulate the drought responses of Leaf Area Index (LAI) and litter production in the Amazon forests is evaluated and several weaknesses are found. Based on the evaluation, an improved version of JSBACH is presented, which is modified based on intensive field measurement from the artificial drought experiments. In the modified JSBACH, a dependency of leaf growth on carbon allocation to leaves is added, and leaf shedding rate is separated into two parts representing aging and water stress. The modified JSBACH is shown to capture the drought responses at different sites in the Amazon. We then couple the modified JSBACH with the atmospheric model ECHAM to simulate the impacts of drought under RCP8.5 scenario. As the vegetation drought response was poorly simulated, we separate the complex drought effects of the Amazon forests to give more insights, which has not been done before. The drought effects are separated into (1) the direct effect resulting from declining soil moisture and stomatal responses, and (2) the LAI effect due to leaf shedding from drier soil. It is shown that the LAI effect accounts for 35% of reduced natural carbon uptake and 12% of surface warming by the end of the 21st century. A comparison with results simulated by the standard JSBACH shows that the model uncertainty associated with LAI and litter production is large for biogeochemical effects, and smaller for biogeophysical effects. In addition, the drought-induced tree mortality is implemented to the model to estimate the impacts. Compared with model version without a drought mortality, the carbon storage is reduced for more than 60%. The results highlight the importance for land surface mod- els to incorporate drought deciduousness and drought mortality for tropical rainforests, in order to have better future climate projections.Die Amazonas-Regenwälder sind einer der größten Ökosystemkohlen- stoffspeicher auf der Erde. Obwohl aufgrund des zukünftigen Klima- wandels häufigere und längere Dürreperioden für die Region vorher- gesagt wurden, ist die Vulnerabilität der Amazonaswälder für Dürren bisher weitgehend ungewiss, da die meisten Landoberflächenmodelle die Reaktion der Vegetation auf Dürren nicht erfassen konnten. In dieser Studie wird die Fähigkeit des hochmodernen Landoberflächen- modells JSBACH bewertet, die Reaktionen des Blattoberflächenindex (LAI) und der Streuproduktion in den Amazonaswäldern auf Dürre zu simulieren, und mehrere Schwachstellen werden festgestellt. Basie- rend auf der Evaluation wird eine verbesserte Version von JSBACH vorgestellt. Diese wurde auf der Grundlage von intensiven Feldmes- sungen künstlicher Dürreexperimente modifiziert. Im modifizierten JSBACH ist eine Abhängigkeit des Blattwachstums von der Kohlen- stoffzuteilung auf die Blätter integriert und die Blattabwurfrate wird in zwei Teile aufgeteilt, die Alterung und Wasserstress repräsentieren. Es wird gezeigt, dass das modifizierte JSBACH die Reaktion auf Dürre an verschiedenen Standorten im Amazonasgebiet erfasst. Das modifizierte JSBACH wird darüber hinaus mit dem atmosphä- rischen Modell ECHAM gekoppelt, um die Auswirkungen von Dürre unter dem RCP8.5-Szenario zu simulieren. Da die Reaktion der Vegeta- tion auf Dürre schlecht simuliert wurde, separieren wir die komplexen Dürreauswirkungen der Amazonaswälder, um bessere Einblicke zu erhalten, was bisher noch nicht gemacht wurde. Die Dürreeffekte werden unterteilt in (1) den direkten Effekt, der sich aus der abneh- menden Bodenfeuchtigkeit und den stomatären Reaktionen ergibt, und (2) den LAI-Effekt aufgrund des Blattabwurfs durch trockenere Böden. Es wird gezeigt, dass der LAI-Effekt zum Ende des 21. Jahrhun- derts für 35% der verringerten natürlichen Kohlenstoffaufnahme und 12% der Oberflächenerwärmung verantwortlich ist. Ein Vergleich mit Ergebnissen, die mit der JSBACH-Standardversion simuliert wurden, zeigt, dass die Modellunsicherheit im Zusammenhang mit dem LAI und der Streuproduktion für biogeochemische Effekte groß und für biogeophysikalische Effekte kleiner ist. Darüber hinaus wird die dürreinduzierte Baumsterblichkeit in das Modell implementiert, um die Auswirkungen abzuschätzen. Verglichen mit der Modellversion ohne Trockenheitsmortalität ist die Kohlenstoffspeicherung um mehr als 60% reduziert. Die Ergebnisse zeigen, wie wichtig es für Landoberflächenmodelle ist, Blattabwurf und Mortalität durch Dürre bei tropischen Regenwäldern einzubeziehen, um bessere Zukunftsklimaprojektionen zu erhalten

Vapor growth of GeTe single crystals in micro-gravity

The positive effects of micro-gravity on crystal growth and fundamental properties of the vapor transport reaction were established by analyzing the results of GeSe and GeTe vapor transport experiments performed on board Skylab. The analysis was based on a direct comparison of GeSe and GeTe crystals and of mass transport rate data obtained on earth and in space. For this purpose, a total of six transport experiments employing different concentrations of transport agent (GeI4) and two temperature gradients were performed during the Skylab 3 and 4 missions. Extensive ground-based studies demonstrated that the crystal morphology and the mass transport rates of the above systems are affected by the transport conditions, in particular by gravity-driven convection. The results demonstrate unambiguously a considerable improvement of the space crystals in terms of surface perfection, crystalline homogeneity and defect density. The observation of greater mass transport rates than expected in micro-gravity environment is of basic scientific and technological significance. This indicates that conventional transport models are incomplete and demonstrates that crystals of improved quality can be grown at reasonable rates by this technique in space. Results are of practical importance for the modification of crystal growth techniques on earth

Investigating the response of leaf area index to droughts in southern African vegetation using observations and model-simulations

In many regions of the world, frequent and continual dry spells are exacerbating drought conditions, which have severe impacts on vegetation biomes. Vegetation in southern Africa is among the most affected by drought. Here, we assessed the spatiotemporal characteristics of meteorological drought in southern Africa using the standardized precipitation evapotranspiration index (SPEI) over a 30-year period (1982–2011). The severity and the effects of droughts on vegetation productiveness were examined at different drought timescales (1- to 24-month timescales). In this study, we characterized vegetation using the leaf area index (LAI) after evaluating its relationship with the normalized difference vegetation index (NDVI). Correlating the LAI with the SPEI, we found that the LAI responds strongly (r=0.6) to drought over the central and southeastern parts of the region, with weaker impacts (r<0.4) over parts of Madagascar, Angola, and the western parts of South Africa. Furthermore, the latitudinal distribution of LAI responses to drought indicates a similar temporal pattern but different magnitudes across timescales. The results of the study also showed that the seasonal response across different southern African biomes varies in magnitude and occurs mostly at shorter to intermediate timescales. The semi-desert biome strongly correlates (r=0.95) to drought as characterized by the SPEI at a 6-month timescale in the MAM (March–May; summer) season, while the tropical forest biome shows the weakest response (r=0.35) at a 6-month timescale in the DJF (December–February; hot and rainy) season. In addition, we found that the spatial pattern of change of LAI and SPEI are mostly similar during extremely dry and wet years, with the highest anomaly observed in the dry year of 1991, and we found different temporal variability in global and regional responses across different biomes. We also examined how well an ensemble of state-of-the-art dynamic global vegetation models (DGVMs) simulate the LAI and its response to drought. The spatial and seasonal response of the LAI to drought is mostly overestimated in the DGVM multimodel ensemble compared to the response calculated for the observation-based data. The correlation coefficient values for the multimodel ensemble are as high as 0.76 (annual) over South Africa and 0.98 in the MAM season over the temperate grassland biome. Furthermore, the DGVM model ensemble shows positive biases (3 months or longer) in the simulation of spatial distribution of drought timescales and overestimates the seasonal distribution timescales. The results of this study highlight the areas to target for further development of DGVMs and can be used to improve the models' capability in simulating the drought–vegetation relationship

Zur Debatte: Deutsch als Wissenschaftssprache

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State-Level Immunization Information Systems: Potential for Childhood Immunization Data Linkages.

Objectives Sources of immunization data include state registries or immunization information systems (IIS), medical records, and surveys. Little is known about the quality of these data sources or the feasibility of using IIS data for research. We assessed the feasibility of collecting immunization information for a national children\u27s health study by accessing existing IIS data and comparing the completeness of these data against medical record abstractions (MRA) and parent report. Staff time needed to obtain IIS and MRA data was assessed. Methods We administered a questionnaire to state-level IIS representatives to ascertain availability and completeness of their data for research and gather information about data formats. We evaluated quality of data from IIS, medical records, and reports from parents of 119 National Children\u27s Study participants at three locations. Results IIS data were comparable to MRA data and both were more complete than parental report. Agreement between IIS and MRA data was greater than between parental report and MRA, suggesting IIS and MRA are better sources than parental report. Obtaining IIS data took less staff time than chart review, making IIS data linkage for research a preferred choice. Conclusions IIS survey results indicate data can be obtained by researchers using data linkages. IIS are an accessible and feasible child immunization information source and these registries reduce reliance on parental report or medical record abstraction. Researchers seeking to link IIS data with large multi-site studies should consider acquiring IIS data, but may need strategies to overcome barriers to data completeness and linkage

Characteristic patterns of inter- and intra-hemispheric metabolic connectivity in patients with stable and progressive mild cognitive impairment and Alzheimer's disease

The change in hypometabolism affects the regional links in the brain network. Here, to understand the underlying brain metabolic network deficits during the early stage and disease evolution of AD (Alzheimer disease), we applied correlation analysis to identify the metabolic connectivity patterns using 18F-FDG PET data for NC (normal control), sMCI (stable MCI), pMCI (progressive MCI) and AD, and explore the inter- and intra-hemispheric connectivity between anatomically-defined brain regions. Regions extracted from 90 anatomical structures were used to construct the matrix for measuring the inter- and intra-hemispheric connectivity. The brain connectivity patterns from the metabolic network show a decreasing trend of inter- and intra-hemispheric connections for NC, sMCI, pMCI and AD. Connection of temporal to the frontal or occipital regions is a characteristic pattern for conversion of NC to MCI, and the density of links in the parietal-occipital network is a differential pattern between sMCI and pMCI. The reduction pattern of inter and intra-hemispheric brain connectivity in the metabolic network depends on the disease stages, and is with a decreasing trend with respect to disease severity. Both frontal-occipital and parietal-occipital connectivity patterns in the metabolic network using 18F-FDG PET are the key feature for differentiating disease groups in AD

Multi-Region Hemispheric Specialization Differentiates Human from Nonhuman Primate Brain Function

The human behavioral repertoire greatly exceeds that of nonhuman primates. Anatomical specializations of the human brain include an enlarged neocortex and prefrontal cortex (Semendeferi et al. in Am J Phys Anthropol 114:224–241, 2001), but regional enlargements alone cannot account for these vast functional differences. Hemispheric specialization has long believed to be a major contributing factor to such distinctive human characteristics as motor dominance, attentional control and language. Yet structural cerebral asymmetries, documented in both humans and some nonhuman primate species, are relatively minor compared to behavioral lateralization. Identifying the mechanisms that underlie these functional differences remains a goal of considerable interest. Here, we investigate the intrinsic connectivity networks in four primate species (humans, chimpanzees, baboons, and capuchin monkeys) using resting-state fMRI to evaluate the intra- and inter- hemispheric coherences of spontaneous BOLD fluctuation. All three nonhuman primate species displayed lateralized functional networks that were strikingly similar to those observed in humans. However, only humans had multi-region lateralized networks, which provide fronto-parietal connectivity. Our results indicate that this pattern of within-hemisphere connectivity distinguishes humans from nonhuman primates