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Sökning: WFRF:(Lange C) > Chalmers tekniska högskola

  • Resultat 1-10 av 11
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1.
  • 2019
  • Tidskriftsartikel (refereegranskat)
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2.
  • de Graauw, Th., et al. (författare)
  • The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
  • 2010
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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3.
  • Roelfsema, P. R., et al. (författare)
  • In-orbit performance of Herschel-HIFI
  • 2012
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: In this paper the calibration and in-orbit performance of the Heterodyne Instrument for the Far-Infrared (HIFI) is described.Methods: The calibration of HIFI is based on a combination of ground and in-flight tests. Dedicated ground tests to determine those instrument parameters that can only be measured accurately using controlled laboratory stimuli were carried out in the instrument level test (ILT) campaign. Special in-flight tests during the commissioning phase (CoP) and performance verification (PV) allowed the determination of the remaining instrument parameters. The various instrument observing modes, as specified in astronomical observation templates (AOTs), were validated in parallel during PV by observing selected celestial sources.Results: The initial calibration and in-orbit performance of HIFI has been established. A first estimate of the calibration budget is given. The overall in-flight instrument performance agrees with the original specification. Issues remain at only a few frequencies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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4.
  • Bergez, J-E, et al. (författare)
  • Integrating agri-environmental indicators, ecosystem services assessment, life cycle assessment and yield gap analysis to assess the environmental sustainability of agriculture.
  • 2022
  • Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 141
  • Tidskriftsartikel (refereegranskat)abstract
    • Agriculture’s primary function is the production of food, feed, fibre and fuel for the fast-growing world population. However, it also affects human health and ecosystem integrity. Policymakers make policies in order to avoid harmful impacts. How to assess such policies is a challenge. In this paper, we propose a conceptual framework to help evaluate the impacts of agricultural policies on the environment. Our framework represents the global system as four subsystems and their interactions. These four components are the cells of a 2 by 2 matrix [Agriculture, Rest of the word]; [Socio-eco system, Ecological system]. We then developed a set of indicators for environmental issues and positioned these issues in the framework. To assess these issues, we used four well-known existing approaches: Life Cycle Assessment, Ecosystem Services Analysis, Yield Gap Analysis and Agro-Environmental Indicators. Using these four approaches together provided a more holistic view of the impacts of a given policy on the system. We then applied our framework on existing cover crop policies using an extensive literature survey and analysing the different environmental issues mobilised by the four assessment approaches. This demonstration case shows that our framework may be of help for a full systemic assessment. Despite their differences (aims, scales, standardization, data requirements, etc.), it is possible and profitable to use the four approaches together. This is a significant step forward, though more work is needed to produce a genuinely operational tool.
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5.
  • Afanaciev, K.G., et al. (författare)
  • Investigation of the radiation hardness of GaAs sensors in an electron beam
  • 2012
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 7:11
  • Tidskriftsartikel (refereegranskat)abstract
    • A compact and finely grained sandwich calorimeter is designed to instrument the very forward region of a detector at a future e+e- collider. The calorimeter will be exposed to low energy e+e - pairs originating from beamstrahlung, resulting in absorbed doses of about one MGy per year. GaAs pad sensors interleaved with tungsten absorber plates are considered as an option for this calorimeter. Several Cr-doped GaAs sensor prototypes were produced and irradiated with 8.5-10 MeV electrons up to a dose of 1.5 MGy. The sensor performance was measured as a function of the absorbed dose.
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6.
  • de Lange, G., et al. (författare)
  • Reversing Quantum Trajectories with Analog Feedback
  • 2014
  • Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:8, s. 5-
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model of quantum trajectories with a measurement efficiency (eta) over tilde approximate to 0.5, consistent with the result obtained by postselection. We overcome the bandwidth limitations of the amplification chain by numerically optimizing the signal processing in the feedback loop and provide a theoretical model explaining the optimization result.
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7.
  • Koundouri, P., et al. (författare)
  • Methodology for Integrated Socio-economic Assessment of Multi-use Offshore Platforms.
  • 2017
  • Ingår i: In: Koundouri P. (eds) The Ocean of Tomorrow. Environment & Policy, vol 56. Springer, Cham. - 9783319557700 ; , s. 11-26
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • This chapter presents the methodology employed for the Integrated Socio-Economic Assessment (MISEA) of different designs of Multi-Use Offshore Platforms (MUOPs). The methodology allows for the identification, the valuationand the assessment of the potential impacts and their magnitude. The analysis considers a number of feasible designs of MUOP investments, and the likely responsesof those impacted by the investment project. The approach provides decision-makers with a valuable tool to assess whether a MUOP project increases the overall social welfare and hence should be undertaken. This is performed under alternative specifications regarding platform design, the discount rate and the stream of net benefits, if a Cost-Benefit Analysis (CBA) is to be followed or a sensitivity analysis of selected criteria in a Multi-Criteria Decision Analysis (MCDA) framework. Themethodology can support the implementation of policies aiming at achieving a goodenvironmental status of the EU’s marine waters and the protection of the resource base upon which marine-related economic and social activities depend.
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8.
  • Kvaerner, A. S., et al. (författare)
  • The CRCbiome study: a large prospective cohort study examining the role of lifestyle and the gut microbiome in colorectal cancer screening participants
  • 2021
  • Ingår i: Bmc Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 21:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Colorectal cancer (CRC) screening reduces CRC incidence and mortality. However, current screening methods are either hampered by invasiveness or suboptimal performance, limiting their effectiveness as primary screening methods. To aid in the development of a non-invasive screening test with improved sensitivity and specificity, we have initiated a prospective biomarker study (CRCbiome), nested within a large randomized CRC screening trial in Norway. We aim to develop a microbiome-based classification algorithm to identify advanced colorectal lesions in screening participants testing positive for an immunochemical fecal occult blood test (FIT). We will also examine interactions with host factors, diet, lifestyle and prescription drugs. The prospective nature of the study also enables the analysis of changes in the gut microbiome following the removal of precancerous lesions. Methods: The CRCbiome study recruits participants enrolled in the Bowel Cancer Screening in Norway (BCSN) study, a randomized trial initiated in 2012 comparing once-only sigmoidoscopy to repeated biennial FIT, where women and men aged 50-74 years at study entry are invited to participate. Since 2017, participants randomized to FIT screening with a positive test result have been invited to join the CRCbiome study. Self-reported diet, lifestyle and demographic data are collected prior to colonoscopy after the positive FIT-test (baseline). Screening data, including colonoscopy findings are obtained from the BCSN database. Fecal samples for gut microbiome analyses are collected both before and 2 and 12 months after colonoscopy. Samples are analyzed using metagenome sequencing, with taxonomy profiles, and gene and pathway content as primary measures. CRCbiome data will also be linked to national registries to obtain information on prescription histories and cancer relevant outcomes occurring during the 10 year follow-up period. Discussion: The CRCbiome study will increase our understanding of how the gut microbiome, in combination with lifestyle and environmental factors, influences the early stages of colorectal carcinogenesis. This knowledge will be crucial to develop microbiome-based screening tools for CRC. By evaluating biomarker performance in a screening setting, using samples from the target population, the generalizability of the findings to future screening cohorts is likely to be high.
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9.
  • Lawrenz, F., et al. (författare)
  • Morphology, mechanical stability, and protective properties of ultrathin gallium oxide coatings
  • 2015
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 31:21, s. 5836-5842
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultrathin gallium oxide layers with a thickness of 2.8 ± 0.2 nm were transferred from the surface of liquid gallium onto solid substrates, including conjugated polymer poly(3-hexylthiophene) (P3HT). The gallium oxide exhibits high mechanical stability, withstanding normal pressures of up to 1 GPa in contact mode scanning force microscopy imaging. Moreover, it lowers the rate of photodegradation of P3HT by 4 orders of magnitude, as compared to uncovered P3HT. This allows us to estimate the upper limits for oxygen and water vapor transmission rates of 0.08 cm3 m-2 day-1 and 0.06 mg m-2 day-1, respectively. Hence, similar to other highly functional coatings such as graphene, ultrathin gallium oxide layers can be regarded as promising candidates for protective layers in flexible organic (opto-)electronics and photovoltaics because they offer permeation barrier functionalities in conjunction with high optical transparency.
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10.
  • Sterner, Thomas, 1952, et al. (författare)
  • Policy design for the Anthropocene
  • 2019
  • Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 2, s. 14-21
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2019, Springer Nature Limited. Today, more than ever, ‘Spaceship Earth’ is an apt metaphor as we chart the boundaries for a safe planet1. Social scientists both analyse why society courts disaster by approaching or even overstepping these boundaries and try to design suitable policies to avoid these perils. Because the threats of transgressing planetary boundaries are global, long-run, uncertain and interconnected, they must be analysed together to avoid conflicts and take advantage of synergies. To obtain policies that are effective at both international and local levels requires careful analysis of the underlying mechanisms across scientific disciplines and approaches, and must take politics into account. In this Perspective, we examine the complexities of designing policies that can keep Earth within the biophysical limits favourable to human life.
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