3,121 research outputs found

    Low-power micro-scale CMOS-compatible silicon sensor on a suspended membrane.

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    In this paper we describe a new, simple and cheap silicon device operating at high temperature at a very low power of a few mW. The essential part of the device is a nano-size conductive link 10-100 nm in size (the so-called antifuse) formed in between two poly-silicon electrodes separated by a thin SiO2 layer. The device can be utilized in chemical sensors or chemical micro-reactors requiring high temperature and very low power consumption e.g. in portable, battery operated systems. As a direct application, we mention a gas sensor (i.e. Pellistor) for hydrocarbons (butane, methane, propane, etc.) based on temperature changes due to the catalytic combustion of hydrocarbons. The power consumed by our device is at about 2% of the power consumed by conventional Pellistors

    Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

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    We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

    Analyzing runtime and size complexity of integer programs

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    We present a modular approach to automatic complexity analysis of integer programs. Based on a novel alternation between finding symbolic time bounds for program parts and using these to infer bounds on the absolute values of program variables, we can restrict each analysis step to a small part of the program while maintaining a high level of precision. The bounds computed by our method are polynomial or exponential expressions that depend on the absolute values of input parameters. We show how to extend our approach to arbitrary cost measures, allowing to use our technique to find upper bounds for other expended resources, such as network requests or memory consumption. Our contributions are implemented in the open source tool KoAT, and extensive experiments show the performance and power of our implementation in comparison with other tools

    Finding Atmospheric Composition (AC) Metadata

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    The Atmospheric Composition Portal (ACP) is an aggregator and curator of information related to remotely sensed atmospheric composition data and analysis. It uses existing tools and technologies and, where needed, enhances those capabilities to provide interoperable access, tools, and contextual guidance for scientists and value-adding organizations using remotely sensed atmospheric composition data. The initial focus is on Essential Climate Variables identified by the Global Climate Observing System CH4, CO, CO2, NO2, O3, SO2 and aerosols. This poster addresses our efforts in building the ACP Data Table, an interface to help discover and understand remotely sensed data that are related to atmospheric composition science and applications. We harvested GCMD, CWIC, GEOSS metadata catalogs using machine to machine technologies - OpenSearch, Web Services. We also manually investigated the plethora of CEOS data providers portals and other catalogs where that data might be aggregated. This poster is our experience of the excellence, variety, and challenges we encountered.Conclusions:1.The significant benefits that the major catalogs provide are their machine to machine tools like OpenSearch and Web Services rather than any GUI usability improvements due to the large amount of data in their catalog.2.There is a trend at the large catalogs towards simulating small data provider portals through advanced services. 3.Populating metadata catalogs using ISO19115 is too complex for users to do in a consistent way, difficult to parse visually or with XML libraries, and too complex for Java XML binders like CASTOR.4.The ability to search for Ids first and then for data (GCMD and ECHO) is better for machine to machine operations rather than the timeouts experienced when returning the entire metadata entry at once. 5.Metadata harvest and export activities between the major catalogs has led to a significant amount of duplication. (This is currently being addressed) 6.Most (if not all) Earth science atmospheric composition data providers store a reference to their data at GCMD

    Wildfire may increase habitat quality for spring Chinook salmon in the Wenatchee River subbasin, WA, USA

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    Pacific Northwest salmonids are adapted to natural disturbance regimes that create dynamic habitat patterns over space and through time. However, human land use, particularly long-term fire suppression, has altered the intensity and frequency of wildfire in forested upland and riparian areas. To examine the potential impacts of wildfire on aquatic systems, we developed stream-reach-scale models of freshwater habitat for three life stages (adult, egg/fry, and juvenile) of spring Chinook salmon (Oncorhynchus tshawytscha) in the Wenatchee River subbasin, Washington. We used variables representing pre- and post-fire habitat conditions and employed novel techniques to capture changes in in-stream fine sediment, wood, and water temperature. Watershed-scale comparisons of high-quality habitat for each life stage of spring Chinook salmon habitat suggested that there are smaller quantities of high-quality juvenile overwinter habitat as compared to habitat for other life stages. We found that wildfire has the potential to increase quality of adult and overwintering juvenile habitat through increased delivery of wood, while decreasing the quality of egg and fry habitat due to the introduction of fine sediments. Model results showed the largest effect of fire on habitat quality associated with the juvenile life stage, resulting in increases in high-quality habitat in all watersheds. Due to the limited availability of pre-fire high-quality juvenile habitat, and increased habitat quality for this life stage post-fire, occurrence of characteristic wildfires would likely create a positive effect on spring Chinook salmon habitat in the Wenatchee River subbasin. We also compared pre- and post-fire model results of freshwater habitat for each life stage, and for the geometric mean of habitat quality across all life stages, using current compared to the historic distribution of spring Chinook salmon. We found that spring Chinook salmon are currently distributed in stream channels in which in-stream habitat for most life stages has a consistently positive response to fire. This compares to the historic distribution of spring Chinook, in which in-stream habitat exhibited a variable response to fire, including decreases in habitat quality overall or for specific life stages. This suggests that as the distribution of spring Chinook has decreased, they now occupy those areas with the most positive potential response to fire. Our work shows the potentially positive link between wildfire and aquatic habitat that supports forest managers in setting broader goals for fire management, perhaps leading to less fire suppression in some situations

    Assessment of Groundnut Elite Lines under Drought Conditions and Selection of Tolerance Associated Traits

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    Investigation of groundnut genotypes response to drought stress could contribute to improving drought tolerance and productivity. The objective of this study was to investigate new improved groundnut varieties response to drought stress under controlled conditions to identify tolerant materials and drought tolerance related traits.Thus, three experiments were conducted during offseasons: two experiments in lysimetric system in 2017 and 2018 and one experiment in pots in 2017, to assess twelve varieties in a randomized complete block design with 2 water regimes and 4 replications.The water regimes were a full irrigation (WW) and an intermittent drought imposed at flowering times (WS). The investigated morphophysiological traits like transpiration, specific leaf area, root dry matter, root length density, and yield components decreased underWS. Significant year effect and genotypic variation were observed on most of investigated traits. Genotypes ICGV 92206 and ICGV 06319 showed low transpiration and revealed high pod yielding and early maturing genotypes under both water regimes, while genotypes ICGV 92035, ICGV 92195, ICGV 02038, ICGV 07211, and ICGV 07210 were drought-sensitive for pods production but produced high haulm under both water regimes. ICGV 92206, ICGV 02005, ICGV 02125, and ICGV 06319 showed higher yielding than 55-437 and Fleur 11. In this study, low total transpiration to control water loss, chlorophyll content, and root length density revealed drought tolerance associated traits for pod production, while TTW, TE, RDW, and RV revealed drought tolerance associated traits for fodder production

    The Space Optical Clocks Project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems

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    The use of ultra-precise optical clocks in space ("master clocks") will allow for a range of new applications in the fields of fundamental physics (tests of Einstein's theory of General Relativity, time and frequency metrology by means of the comparison of distant terrestrial clocks), geophysics (mapping of the gravitational potential of Earth), and astronomy (providing local oscillators for radio ranging and interferometry in space). Within the ELIPS-3 program of ESA, the "Space Optical Clocks" (SOC) project aims to install and to operate an optical lattice clock on the ISS towards the end of this decade, as a natural follow-on to the ACES mission, improving its performance by at least one order of magnitude. The payload is planned to include an optical lattice clock, as well as a frequency comb, a microwave link, and an optical link for comparisons of the ISS clock with ground clocks located in several countries and continents. Undertaking a necessary step towards optical clocks in space, the EU-FP7-SPACE-2010-1 project no. 263500 (SOC2) (2011-2015) aims at two "engineering confidence", accurate transportable lattice optical clock demonstrators having relative frequency instability below 1\times10^-15 at 1 s integration time and relative inaccuracy below 5\times10^-17. This goal performance is about 2 and 1 orders better in instability and inaccuracy, respectively, than today's best transportable clocks. The devices will be based on trapped neutral ytterbium and strontium atoms. One device will be a breadboard. The two systems will be validated in laboratory environments and their performance will be established by comparison with laboratory optical clocks and primary frequency standards. In this paper we present the project and the results achieved during the first year.Comment: Contribution to European Frequency and Time Forum 2012, Gothenburg, Swede
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