1,127 research outputs found

    The Tropospheric Lifetimes of Halocarbons and Their Reactions with OH Radicals: an Assessment Based on the Concentration of CO-14

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    Chemical reaction with hydroxyl radicals formed in the troposphere from ozone photolysis in the presence of methane, carbon monoxide and nitrogen oxides provides an important removal mechanism for halocarbons containing C-H and C = C double bonds. The isotropic distribution in atmospheric carbon monoxide was used to quantify the tropospheric hydroxyl radical distribution. Here, this methodology is reevaluated in the light of recent chemical kinetic data evaluations and new understandings gained in the life cycles of methane and carbon monoxide. None of these changes has forced a significant revision in the CO-14 approach. However, it is somewhat more clearly apparent how important basic chemical kinetic data are to the accurate establishment of the tropospheric hydroxyl radical distribution

    Observation of molecules produced from a Bose-Einstein condensate

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    Molecules are created from a Bose-Einstein condensate of atomic 87Rb using a Feshbach resonance. A Stern-Gerlach field is applied, in order to spatially separate the molecules from the remaining atoms. For detection, the molecules are converted back into atoms, again using the Feshbach resonance. The measured position of the molecules yields their magnetic moment. This quantity strongly depends on the magnetic field, thus revealing an avoided crossing of two bound states at a field value slightly below the Feshbach resonance. This avoided crossing is exploited to trap the molecules in one dimension.Comment: 4 pages, 4 figures, minor revison

    Predictors of family communication of one’s organ donation intention in Switzerland

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    OBJECTIVES: Family members continue to play a prominent role in decisions to donate organs at the time of death. Prior knowledge of the deceased's intention to donate was identified as an important influential factor in the donation decision-making process. This study examined what factors lead to family communication of a person's wish regarding organ donation. METHODS: A population-based survey was used to identify the prevalence of people who had informed family members of their intention to donate. Associated factors were evaluated using bivariate and multivariate analyses. RESULTS: Multivariate analysis revealed that communication to a family member of the intention to donate organs was more likely if the respondent had a signed donor card (OR = 10.23, CI = 5.25-19.93), had a family discussion on organ donation or transplantation (OR = 7.12, CI = 4.91-10.34), had a partner and knew his or her attitude to organ donation (OR = 5.76, CI = 4.20-7.90), had previously personally had a good look at the issue of organ donation (OR = 2.59, CI = 1.79-3.75), was rather younger (OR = 0.98, CI = 0.97-0.99), was of Swiss nationality (OR = 2.21, CI = 1.25-3.91), felt that he or she was sufficiently informed (OR = 2.10, CI = 1.50-2.94), had the information necessary to come to an appropriate decision on organ donation and-although this relation may be weaker-were (rather) willing to become an organ donor after death (OR = 1.41, CI = 1.01-1.97). CONCLUSIONS: Our findings highlight the need for public education and community campaigns to promote the need to share with others, the intention to donate and to increase people's knowledge on this issue

    In-situ comparison of the NOy instruments flown in MOZAIC and SPURT

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    Two aircraft instruments for the measurement of total odd nitrogen (NOy) were compared side by side aboard a Learjet A35 in April 2003 during a campaign of the AFO2000 project SPURT (Spurengastransport in der Tropopausenregion). The instruments albeit employing the same measurement principle (gold converter and chemiluminescence) had different inlet configurations. The ECO-Physics instrument operated by ETH-ZĂŒrich in SPURT had the gold converter mounted outside the aircraft, whereas the instrument operated by FZ-JĂŒlich in the European project MOZAIC III (Measurements of ozone, water vapour, carbon monoxide and nitrogen oxides aboard Airbus A340 in-service aircraft) employed a Rosemount probe with 80 cm of FEP-tubing connecting the inlet to the gold converter. The NOy concentrations during the flight ranged between 0.3 and 3 ppb. The two data sets were compared in a blind fashion and each team followed its normal operating procedures. On average, the measurements agreed within 7%, i.e. within the combined uncertainty of the two instruments. This puts an upper limit on potential losses of HNO3 in the Rosemount inlet of the MOZAIC instrument. Larger transient deviations were observed during periods after calibrations and when the aircraft entered the stratosphere. The time lag of the MOZAIC instrument observed in these instances is in accordance with the time constant of the MOZAIC inlet line determined in the laboratory for HNO3

    Ensemble-induced strong light-matter coupling of a single quantum emitter

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    We discuss a technique to strongly couple a single target quantum emitter to a cavity mode, which is enabled by virtual excitations of a nearby mesoscopic ensemble of emitters. A collective coupling of the latter to both the cavity and the target emitter induces strong photon non-linearities in addition to polariton formation, in contrast to common schemes for ensemble strong coupling. We demonstrate that strong coupling at the level of a single emitter can be engineered via coherent and dissipative dipolar interactions with the ensemble, and provide realistic parameters for a possible implementation with SiV−^{-} defects in diamond. Our scheme can find applications, amongst others, in quantum information processing or in the field of cavity-assisted quantum chemistry.Comment: 13 pages, 6 figures; substantially revised manuscript; see arXiv:1912.12703 for mathematical derivation

    A Total Cost of Ownership Model for Cloud Computing Infrastructure

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    A holistic cost assessment of cloud computing ar-chitectures is currently hampered by the lack of assessment methods and the absence of a standardized and comprehensive total cost model. This creates uncertainty about cost developments of concrete scenarios and architectural changes. This article proposes a total cost of ownership model for cloud computing, covering the cost of adoption, procurement, migration, operation, usage, and exit. We evaluated our model in multiple application scenarios and against other models. Our model has shown to be substantially more comprehensive and applicable than other available models for cloud computing. Thus, our model can be useful both in practice and in research. We will demonstrate that our model can increase cost transparency and improve decision support

    Thermal Excitation of Broadband and Long-range Surface Waves on SiO 2 Submicron Films

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    We detect thermally excited surfaces waves on a submicron SiO 2 layer, including Zenneck and guided modes in addition to Surface Phonon Polaritons. The measurements show the existence of these hybrid thermal-electromagnetic waves from near-(2.7 Ό\mum) to far-(11.2 Ό\mum) infrared. Their propagation distances reach values on the order of the millimeter, several orders of magnitude larger than on semi-infinite systems. These two features, spectral broadness and long range propagation, make these waves good candidates for near-field applications both in optics and thermics due to their dual nature.Comment: Applied Physics Letters, American Institute of Physics, 201

    Feshbach Spectroscopy of a Shape Resonance

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    We present a new spectroscopy technique for studying cold-collision properties. The technique is based on the association and dissociation of ultracold molecules using a magnetically tunable Feshbach resonance. The energy and lifetime of a shape resonance are determined from a measurement of the dissociation rate. Additional spectroscopic information is obtained from the observation of a spatial interference pattern between an outgoing s wave and d wave. The experimental data agree well with the results from a new model, in which the dissociation process is connected to a scattering gedanken experiment, which is analyzed using a coupled-channels calculation.Comment: Introduction rewritte
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