Magnetische Metall/Polymer Nanokomposite für Hochfrequenzanwendungen

In der heutigen Gesellschaft spielt der mobile Kommunikations- und Datenverkehr eine immer größere Rolle. Mit diesem massiv wachsenden Markt geht ein dementsprechender Entwicklungsbedarf im Bereich der dazugehörigen, technologischen Komponenten einher. So ist es ein Entwicklungsziel, die induktiven Komponenten, wie sie z.B. in MMICs (Monolithic Microwave Integrated Circuit) integriert sind, immer weiter zu verkleinern, während gleichzeitig ebenfalls ihre Hochfrequenzeigenschaften verbessert werden sollen. Integrierte Mikroinduktoren bestehen beim heutigen Stand der Technik in den meisten Fällen aus planaren Spiralen ohne einen magnetischen Kern, welche eine relativ große Oberfläche auf einem Chip belegen. Die Verwendung von Mikroinduktoren mit einem weichmagnetischen Kernmaterial führt durch die Erhöhung der Induktivität und des Gütefaktors zu einer erwünschten Verkleinerung bei gleichzeitiger Verringerung von Streufeldern. Neben den Geometrien der Mikroinduktoren selbst ist die Entwicklung geeigneter weichmagnetischer Dünnfilme von entscheidender Bedeutung. Der in dieser Arbeit verfolgte Ansatz zur Herstellung solcher weichmagnetischer Schichten besteht in der Verwendung von Metall/Polymer Nanokompositen. Diese wurden über eine Abscheidung von weichmagnetischen Legierungen zusammen mit Fluorpolymeren mittels Vakuum-Gasphasenabscheideverfahren realisiert. Die Abscheidung der beiden Komponenten erfolgte sowohl gleichzeitig als auch abwechselnd, wodurch verschiedene Nanostrukturen des Komposits realisiert wurden. Die Filme wurden hinsichtlich der Struktur und Zusammensetzung der Komposite und auch hinsichtlich ihrer magnetischen Eigenschaften charakterisiert. Nanostrukturierte FeNiCo/PTFE-Multilagenfilme, bei denen während der Abscheidung eine Anisotropie über ein statisches Magnetfeld induziert wurde, weisen eine Resonanzfrequenz von fr = 4,8 GHz und eine Hochfrequenzpermeabilität µ’ ≈ 60 bei 100 MHz auf. Es treten keine signifikanten Verluste bei Frequenzen < 1,5 GHz auf, und es ergibt sich ein sehr guter Gütefaktor Q = 20 bei 2 GHz für diese Kompositfilme. Diese Eigenschaften sind eine exzellente Grundlage für den Einsatz der Filme als Kernmaterial in Mikroinduktoren. Die Integrierbarkeit der Metall/Polymer Nanokompositfilme in standard-CMOS Prozessverfahren wurde anhand eines toroidförmigen Mikroinduktors erfolgreich umgesetzt. Weiterhin wurde ein faszinierender, neuer und selbstorganisierter Wachstumsprozess untersucht. Beim Co-Verdampfen einer FeNiCo Legierung mit Teflon AF entsteht bei geeigneten Prozessparametern ein Nanokomposit, bestehend aus magnetischen Nanosäulen mit einem Durchmesser von wenigen Nanometern und hohem Aspektverhältnis, eingebettet in einer isolierenden Polymermatrix. Dieser Wachstumsprozess und die magnetischen Eigenschaften solcher Nanosäulen-Kompositfilme wurde im Verlauf dieser Arbeit genauer untersucht

CO Emission in Low Luminosity, HI Rich Galaxies

We present 12CO 1-0 observations of eleven low luminosity M_B > -18), HI--rich dwarf galaxies. Only the three most metal-rich galaxies, with 12+log(O/H) ~ 8.2, are detected. Very deep CO spectra of six extremely metal-poor systems (12+log(O/H) < 7.5) yield only low upper limits on the CO surface brightness, I_CO < 0.1 K km/s. Three of these six have never before been observed in a CO line, while the others now have much more stringent upper limits. For the very low metallicity galaxy Leo A, we do not confirm a previously reported detection in CO, and the limits are consistent with another recent nondetection. We combine these new observations with data from the literature to form a sample of dwarf galaxies which all have CO observations and measured oxygen abundances. No known galaxies with 12+log(O/H) < 7.9 (Z < 0.1 solar) have been detected in CO. Most of the star-forming galaxies with higher (12+log(O/H) > 8.1) metallicities are detected at similar or higher I_CO surface brightnesses. The data are consistent with a strong dependence of the I_CO/M_H_2 = X_CO conversion factor on ambient metallicity. The strikingly low upper limits on some metal-poor galaxies lead us to predict that the conversion factor is non-linear, increasing sharply below approximately 1/10 of the solar metallicity (12+log(O/H) < 7.9).Comment: 25 pages, 4 figures, 3 tables. Accepted for publication in AJ Tables replaced -- now formated for landscape orientatio

The Sunyaev-Zel'dovich effect in WMAP data

Using WMAP 5 year data, we look for the average Sunyaev-Zel'dovich effect (SZE) signal from clusters of galaxies by stacking the regions around hundreds of known X-ray clusters. We detect the average SZE at a very high significance level. The average cluster signal is spatially resolved in the W band. This mean signal is compared with the expected signal from the same clusters calculated on the basis of archival ROSAT data. From the comparison we conclude that the observed SZE seems to be less than the expected signal derived from X-ray measurements when a standard beta-model is assumed for the gas distribution. This conclusion is model dependent. Our predictions depend mostly on the assumptions made about the core radius of clusters and the slope of the gas density profile. Models with steeper profiles are able to simultaneously fit both X-ray and WMAP data better than a beta-model. However, the agreement is not perfect and we find that it is still difficult to make the X-ray and SZE results agree. A model assuming point source contamination in SZE clusters renders a better fit to the one-dimensional SZE profiles thus suggesting that contamination from point sources could be contributing to a diminution of the SZE signal. Selecting a model that better fits both X-ray and WMAP data away from the very central region, we estimate the level of contamination and find that on average, the point source contamination is on the level of 16 mJy (at 41 GHz), 26 mJy (at 61 GHz) and 18 mJy (at 94 GHz). These estimated fluxes are marginally consistent with the estimated contamination derived from radio and infrared surveys thus suggesting that the combination of a steeper gas profile and the contribution from point sources allows us to consistently explain the X-ray emission and SZE in galaxy clusters as measured by ROSAT and WMAP.Comment: 17 pages and 17 figures. Submited to MNRA

Climate change will disproportionally affect the most genetically diverse lineages of a widespread African tree species

Global climate change is proceeding at an alarming rate with major ecological and genetic consequences for biodiversity, particularly in drylands. The response of species to climate change may difer between intraspecifc genetic groups, with major implications for conservation. We used molecular data from 10 nuclear and two chloroplast genomes to identify phylogeographic groups within 746 individuals from 29 populations of Senegalia senegal, a savannah tree species in subSaharan Africa. Three phylogroups are identifed corresponding to Sudano-Sahelian, Zambezian and Southern African biogeographic regions in West, East and Southern Africa. Genetic diversity was highest in Southern and Zambesian and lowest in the Sudano-Sahelian phylogroups. Using species distribution modeling, we infer highly divergent future distributions of the phylogroups under three climate change scenarios. Climate change will lead to severe reductions of distribution area of the genetically diverse Zambezian (−41–− 54%) and Southern (− 63–− 82%) phylogroups, but to an increase for the genetically depauperate Sudano-Sahelian (+ 7– + 26%) phylogroups. This study improves our understanding of the impact of climate change on the future distribution of this species. This knowledge is particularly useful for biodiversity management as the conservation of genetic resources needs to be considered in complementary strategies of in-situ conservation and assisted migration.The German Academic Exchange Service, the German Science Foundation, the German Federal Ministry of Education and Research and Leipzig University.https://www.nature.com/srepPlant Production and Soil Scienc

Interdisciplinary European guidelines on surgery of severe obesity

W 2005 roku, dzięki wspólnemu wysiłkowi głównych europejskich towarzystw naukowych aktywnych na polu leczenia otyłości został powołany zespół ekspertów nazwany Bariatryczno-Naukową Grupą Badawczą (BSCG). Towarzystwami, które stworzyły ten zespół i oddelegowały swoich przedstawicieli do prac w opracowaniu wytycznych były: Międzynarodowe Towarzystwo Chirurgicznego Leczenia Otyłości (IFSO), Oddział Europejski Międzynarodowego Towarzystwa Chirurgicznego Leczenia Otyłości (IFSO-EC), Europejskie Towarzystwo Badań nad Otyłością (EASO), Europejska Grupa ds. Otyłości u Dzieci (ECOG) (razem z Międzynarodową Grupą Zwalczania Otyłości). Bariatryczno-Naukowa Grupa Badawcza składała się z władz reprezentujących powyższe towarzystwa (czterech czynnych przewodniczących, dwóch byłych, jeden honorowy, dwóch dyrektorów wykonawczych), a także najwybitniejszych ekspertów w tej dziedzinie. Skład BSCG pozwolił na całościowe objęcie zagadnienia leczenia otyłości olbrzymiej z uwzględnieniem różnorodności geograficznej i etnicznej Europy. Członkowie BSCG odbyli wiele spotkań poświęconych stworzeniu wytycznych, które odzwierciedlałyby współczesną wiedzę i doświadczenie w zakresie leczenia otyłości olbrzymiej.In 2005, for the first time in European history, an extraordinary expert panel named BSCG (Bariatric Scientific Collaborative Group), was appointed through joint effort of the major European scientific societies which are active in the field of obesity management. Societies that constituted this panel were: IFSO - International Federation for the Surgery of Obesity, IFSO-EC - International Federation for the Surgery of Obesity - European Chapter, EASO - European Association for Study of Obesity, ECOG - European Childhood Obesity Group, together with the IOTF (International Obesity Task Force) which was represented during the completion process by its representative. The BSCG was composed not only of the top officers representing the respective scientific societies (four acting presidents, two past presidents, one honorary president, two executive directors), but was balanced with the presence of many other key opinion leaders in the field of obesity. The BSCG composition allowed the coverage of key disciplines in comprehensive obesity management, as well as reflecting European geographical and ethnic diversity. This joint BSCG expert panel convened several meetings which were entirely focused on guidelines creation, during the past 2 years. There was a specific effort to develop clinical guidelines, which will reflect current knowledge, expertise and evidence based data on morbid obesity treatment

Stability of grassland soil C and N pools despite 25years of an extreme climatic and disturbance regime

Citation: Wilcox, K. R., Blair, J. M., & Knapp, A. K. (2016). Stability of grassland soil C and N pools despite 25years of an extreme climatic and disturbance regime. Journal of Geophysical Research-Biogeosciences, 121(7), 1934-1945. doi:10.1002/2016jg003370Global changes are altering many important drivers of ecosystem functioning, with precipitation amount and disturbance frequency being especially important. Carbon (C) and nitrogen (N) pools are key contemporary attributes of ecosystems that can also influence future C uptake via plant growth. Thus, understanding the impacts of altered precipitation amounts (through controls of primary production inputs) and disturbance regimes (through losses of C and N in biomass) is important to project how ecosystem services will respond to future global changes. A major difficulty inherent within this task is that drivers of ecosystem function and processes often interact, resulting in novel ecosystem responses. To examine how changes in precipitation affect grassland ecosystem responses under a frequent disturbance regime (annual fire), we assessed the biogeochemical and ecological consequences of more than two decades of irrigation in an annually burned mesic grassland in the central United States. In this experiment, precipitation amount was increased by 31% relative to ambient and 1 in 3years were statistically extreme relative to the long-term historical record. Despite evidence that irrigation decreased root:shoot ratios and increased rates of N cyclingeach expected to reduce soil C and N with annual burningwe detected no changes in these biogeochemical pools. This surprising biogeochemical resistance highlights the need to explore additional mechanisms within long-term experiments concerning the consequences of global change impacts on ecosystems

The configuration, sensitivity and rapid retreat of the Late Weichselian Icelandic ice sheet

The fragmentary glacial-geological record across the Icelandic continental shelf has hampered reconstruction of the volume, extent and chronology of the Late Weichselian ice sheet particularly in key offshore zones. Marine geophysical data collected over the last two decades reveal that the ice sheet likely attained a continental shelf-break position in all sectors during the Last Glacial Maximum, though its precise timing and configuration remains largely unknown. Within this context, we review the available empirical evidence and use a well-constrained three-dimensional thermomechanical model to investigate the drivers of an extensive Late Weichselian Icelandic ice-sheet, its sensitivity to environmental forcing, and phases of deglaciation. Our reconstruction attains the continental shelf break across all sectors with a total ice volume of 5.96&times;105km3&nbsp;with high precipitation rates being critical to forcing extensive ice sheet flow offshore. Due to its location astride an active mantle plume, a relatively fast and dynamic ice sheet with a low aspect ratio is maintained. Our results reveal that once initial ice-sheet retreat was triggered through climate warming at 21.8 ka BP, marine deglaciation was rapid and accomplished in all sectors within c. 5 ka at a mean rate of 71 Gt of mass loss per year. This rate of ice wastage is comparable to contemporary rates observed for the West Antarctic ice sheet. The ice sheet subsequently stabilised on shallow pinning points across the near shelf for two millennia, but abrupt atmospheric warming during the B&oslash;lling Interstadial forced a second, dramatic collapse of the ice sheet onshore with a net wastage of 221 Gt a&minus;1&nbsp;over 750 years, analogous to contemporary Greenland rates of mass loss. Geothermal conditions impart a significant control on the ice sheet's transient response, particularly during phases of rapid retreat. Insights from this study suggests that large sectors of contemporary ice sheets overlying geothermally active regions, such as Siple Coast, Antarctica, and NE Greenland, have the potential to experience rapid phases of mass loss and deglaciation once initial retreat is initiated

Test-retest and between-site reliability in a multicenter fMRI study

In the present report, estimates of test–retest and between-site reliability of fMRI assessments were produced in the context of a multicenter fMRI reliability study (FBIRN Phase 1, www.nbirn.net). Five subjects were scanned on 10 MRI scanners on two occasions. The fMRI task was a simple block design sensorimotor task. The impulse response functions to the stimulation block were derived using an FIR-deconvolution analysis with FMRISTAT. Six functionally-derived ROIs covering the visual, auditory and motor cortices, created from a prior analysis, were used. Two dependent variables were compared: percent signal change and contrast-to-noise-ratio. Reliability was assessed with intraclass correlation coefficients derived from a variance components analysis. Test–retest reliability was high, but initially, between-site reliability was low, indicating a strong contribution from site and site-by-subject variance. However, a number of factors that can markedly improve between-site reliability were uncovered, including increasing the size of the ROIs, adjusting for smoothness differences, and inclusion of additional runs. By employing multiple steps, between-site reliability for 3T scanners was increased by 123%. Dropping one site at a time and assessing reliability can be a useful method of assessing the sensitivity of the results to particular sites. These findings should provide guidance to others on the best practices for future multicenter studies

The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI