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This paper introduces a differential vibrating beam MEMS accelerometer demonstrating excellent long-term stability for applications in gravimetry and seismology. The MEMS gravimeter module demonstrates an output Allan deviation of 9 μGal for a 1000 s integration time, a noise floor of 100 μGal/√Hz, and measurement over the full ±1 g dynamic range (1 g = 9.81 ms −2 ). The sensitivity of the device is demonstrated through the tracking of Earth tides and recording of ground motion corresponding to a number of teleseismic events over several months. These results demonstrate that vibrating beam MEMS accelerometers can be employed for measurements requiring high levels of stability and resolution with wider implications for precision measurement employing other resonant-output MEMS devices such as gyroscopes and magnetometers.

In this paper, we present a new method to study global atmospheric processes and their changes during the last decade. A cosmogenic radionuclide measured at ground-level, beryllium-7, is utilized as a proxy to study atmospheric dynamics. Beryllium-7 has two advantages: First, this radionuclide, primarily created in the lower stratosphere, attaches to aerosols that are transported downwards to the troposphere and travel around the globe with the general atmospheric circulation. By monitoring these particles, we can provide a global, simple, and sustainable way to track processes such as multi-annual variation of the troposphere, tropopause heightening, position and speed of atmospheric interface zones, as well as the poleward movement and stalling patterns of jet streams. Second, beryllium-7 is a product of cosmic rays which are themselves directly linked to solar activity and the earth magnetic field. This study shows whether beryllium-7 observed concentration changes are correlated with such natural processes or independent of them. Our work confirms that major changes in the atmospheric circulation are currently ongoing, even though timeseries are too short to make climatological assessments. We provide solid evidence of significant and progressive changes of the global atmospheric circulation as well as modifications of tropopause heights over the past decade. As the last decade happened to be the warmest on record, this analysis also indicates that the observed changes are, at least to some extent, attributable to global warming.

Background and aims Uptake of 90 Sr and 137 Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by site-specific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the 137 Cs and 90 Sr transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. Methods We carried out a field study on the 90 Sr and 137 Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Conclusions Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the 90 Sr results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales ( Phleum rhaeticum ) concentrating much less 90 Sr than Eudicots do.

Power metal-oxide-semiconductor field-effect transistors (MOSFETs) experience conditions of high field during normal operation. During switching conditions, unexpected transient events may occur which force devices into avalanche or short circuit conditions. Moreover, silicon carbide devices typically experience higher fields in the gate oxide and drift regions than comparable Si devices due to channel and drift property differences. A summary of SiC MOSFET reliability and ruggedness test results are reported here. Reliability tests under high field conditions: positive-bias and negative-bias temperature instability (PBTI, NBTI) to examine threshold stability; time-dependent dielectric breakdown (TDDB) for gate oxide lifetime extrapolation; high-temperature reverse bias (HTRB); and HTRB testing under high neutron flux to determine terrestrial neutron single-event burnout (SEB) rates. High-power ruggedness evaluation is presented for SiC MOSFETs under forced avalanche conditions (unclamped inductive switching (UIS)) and under short-circuit operation to bound device safe operating areas. Overall results demonstrate the intrinsic reliability of SiC MOSFETs.

Uptake of ^sup 90^Sr and ^sup 137^Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by site-specific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the ^sup 137^Cs and ^sup 90^Sr transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. We carried out a field study on the ^sup 90^Sr and ^sup 137^Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the ^sup 90^Sr results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales (Phleum rhaeticum) concentrating much less ^sup 90^Sr than Eudicots do.[PUBLICATION ABSTRACT]

Background and aims Uptake of 90Sr and 137Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by site-specific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the 137Cs and 90Sr transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. Methods We carried out a field study on the 90Sr and 137Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Conclusions Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the 90Sr results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales (Phleum rhaeticum) concentrating much less 90Sr than Eudicots do.

Background and aims Uptake of [sup.90.Sr] and [sup.137]Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by sitespecific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the [sup.137]Cs and [sup.90.Sr] transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. Methods We carried out a field study on the [sup.90.Sr] and [sup.137]Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Conclusions Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the [sup.90.Sr] results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales (Phleum rhaeticum) concentrating much less [sup.90.Sr] than Eudicots do. Keywords [sup.90.Sr] * [sup.137]Cs * Plant * Phylogenetic effect * Uptake * Soil

Background and aims: Uptake of super(90)Sr and super(137)Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by site-specific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the super(137)Cs and super(90)Sr transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. Methods: We carried out a field study on the super(90)Sr and super(137)Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results: Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Conclusions: Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the super(90)Sr results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales (Phleum rhaeticum) concentrating much less super(90)Sr than Eudicots do.

The Faraoni Level is a short-lived oxygen-deficient event that took place during the latest Hauterivian. In order to improve our understanding of the palaeoenvironmental conditions that occurred during this event, we have analysed the contents of several redox-sensitive trace elements (U, V, Mo, As, Co, Cd, Cu, Zn, Ni, Pb, Cr) from bulk limestone samples of late Hauterivian–early Barremian age from three reference sections. U, V, Mo and As show consistent and significant enrichments during the Faraoni event whereas the other redox-sensitive trace elements analysed here are not systematically enriched. In order to explain this discrepant behaviour, we propose that the Faraoni Level was deposited during a period of anoxic conditions near the sediment–water interface. The distinctive peaks in U, V, Mo and As contents are traceable throughout the three studied sections and represent a good correlation tool which helps to identify the Faraoni Level and its equivalents in the western Tethyan realm and outside of the Tethys. For example, a peak in U contents in upper Hauterivian sediments of the northwestern Pacific realm (ODP leg 185, site 1149) may well be an expression of the Faraoni event in this particular basin.

A method for the fabrication of highly defined metallic tunnel junctions based on the Step-Edge Cut-Off (SECO) process is described. Fabrication involved electron beam lithography and lift-off of metallic thin films. Junctions with sub-3 nm gaps and scaling down to 50 nm line-width have been achieved. A measurement system for the measurement of single electron devices capable of using both DC and AC excitation signals and low excitation power was constructed. Devices measured at 77 K showed a spread in impedance at low bias ranging from less than 10 MΩ to more than 100 GΩ. The behavior of thin metallic films across a step forming a single tunnel junction was investigated. In the case of Palladium, it was found that grain growth during deposition can give rise to multiple junctions across a single step. This is illustrated using one particular example of a junction, where isolated grains form a spontaneous Coulomb blockaded island with a charging energy of ~ 20 meV at 77 K. A simplified measurement technique was developed for rapid screening of devices, which aided the development process. Post-processing of fabricated devices was investigated to address the spread in impedance. One method involved the deposition of Diamond like-Carbon (DLC) in a conventional scanning electron microscope on fabricated structured and was found to yield devices with a spread in impedance from 220 kΩ to 2.8 GΩ. Another route involved an additional etching step to form a \"free-floating\" metallic island connected to metallic electrodes at the edges. Electrodes insulated using a self-assembled monolayer (SAM) of hexanethiol and non-insulated electrodes were used. Devices with tunnel impedances as low as 4 MΩ were measured at room temperature and in air. The SECO structures were modelled in two and three dimensions, using an industrial finite-element modelling package, Taurus-Medici. Capacitances were extracted and found to range from 12 aF to 80 aF, corresponding to a T0 of 77 K and 12 K respectively. As a final demonstration of a complete process flow, a deep silicon reactive ion etch was successfully employed to define and release silicon cantilevers, on which double tunnel junction structures had been lithographically defined.