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Search Results: 1 - 10 of 208478 matches for " L. Greuter "
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Probing single charge fluctuations in a semiconductor with laser spectroscopy on a quantum dot
J. Houel,A. Kuhlmann,L. Greuter,F. Xue,M. Poggio,B. D. Gerardot,P. A. Dalgarno,A. Badolato,P. M. Petroff,A. Ludwig,D. Reuter,A. D. Wieckand,R. J. Warburton
Physics , 2011, DOI: 10.1103/PhysRevLett.108.107401
Abstract: We probe local charge fluctuations in a semiconductor via laser spectroscopy on a nearby self-assembled quantum dot. We demonstrate that the quantum dot is sensitive to changes in the local environment at the single charge level. By controlling the charge state of localized defects, we are able to infer the distance of the defects from the quantum dot with +-5 nm resolution. The results identify and quantify the main source of charge noise in the commonly-used optical field-effect devices. Based on this understanding we achieve routinely close-totransform-limited quantum dot optical linewidths.
A new Australian species of Luffa (Cucurbitaceae) and typification of two Australian Cucumis names, all based on specimens collected by Ferdinand Mueller in 1856
Ian R. H. Telford,Hanno Schaefer,Werner Greuter,Susanne Renner
PhytoKeys , 2011, DOI: 10.3897/phytokeys.5.1395
Abstract: As a result of his botanical explorations in northern Australia, Ferdinand von Mueller named several Cucurbitaceae that molecular data now show to be distinct, requiring their resurrection from unjustified synonymy. We here describe Luffa saccata F. Muell. ex I.Telford, validating a manuscript name listed under L. graveolens Roxb. since 1859, and we lectotypify Cucumis picrocarpus F. Muell. and C. jucundus F. Muell. The lectotype of the name C. picrocarpus is a sprig that is mounted on the same sheet as the lectotype of C. jucundus, a synonym of C. melo. We also illustrate the new species Luffa saccata. Cucumis picrocarpus is the sister species of the cultivated C. melo and was illustrated in a recent publication.
Biological nomenclature terms for facilitating communication in the naming of organisms
John David,George Garrity,W. Greuter,David Hawksworth
ZooKeys , 2012, DOI: 10.3897/zookeys.192.3347
Abstract: A set of terms recommended for use in facilitating communication in biological nomenclature is presented as a table showing broadly equivalent terms used in the traditional Codes of nomenclature. These terms are intended to help those engaged in naming across organism groups, and are the result of the work of the International Committee on Bionomenclature, whose aim is to promote harmonisation and communication amongst those naming life on Earth.
Towards high cooperativity strong coupling of a quantum dot in a tunable microcavity
Lukas Greuter,Sebastian Starosielec,Andreas V. Kuhlmann,Richard J. Warburton
Physics , 2015, DOI: 10.1103/PhysRevB.92.045302
Abstract: We investigate the strong coupling regime of a self-assembled quantum dot in a tunable microcavity with dark-field laser spectroscopy. The high quality of the spectra allows the lineshapes to be analyzed revealing subtle quantum interferences. Agreement with a model calculation is achieved only by including exciton dephasing which reduces the cooperativity from a bare value of 9.0 to the time-averaged value 5.5. In the pursuit of high cooperativity, besides a high-Q and low mode-volume cavity, we demonstrate that equal efforts need to be taken towards lifetime-limited emitter linewidths.
Quality of guidelines on the management of diabetes in pregnancy: a systematic review
Marjolein JE Greuter, Nathalie MA van Emmerik, Maurice GAJ Wouters, Maurits W van Tulder
BMC Pregnancy and Childbirth , 2012, DOI: 10.1186/1471-2393-12-58
Abstract: Guidelines were selected by searching PubMed, the Guideline Clearing House and Google. All guidelines developed since 2000 on diabetes during pregnancy in English or Dutch were considered. Recommendations of the guidelines were compared. Furthermore, the quality was assessed by two authors independently, using the AGREE instrument.Eight guidelines were included. According to the AGREE instrument, the quality of most guidelines was low. The domains editorial independence, stakeholder involvement and rigour of development had the lowest scores. Recommendations were mainly comparable on glycemic control, preconceptional counseling and prenatal care and labour. Differences between recommendations were found for screening on GDM and induction of labour.The quality of most guidelines concerning the management of diabetes during pregnancy needs to be improved. A more systematic approach in the development of these guidelines, more attention for updating procedures and piloting of the guidelines and involvement of target users and patients is recommended.Diabetes during pregnancy can lead to serious risks for both mother and fetus [1]. The management of diabetes differs between women with gestational diabetes mellitus (GDM) and pregnant women with pre-existing diabetes mellitus type 1 (DM1) or type 2 (DM2).GDM develops often towards the end of the second trimester [1]. Maternal risk factors for GDM are: a BMI above 30 kg/m2, history of unexplained intrauterine fetal death, previous GDM or a macrosomic baby, family history of DM, polycystic ovarian syndrome and ethnicity. Especially women of South Asian, Black Caribbean and Middle Eastern origin have an increased risk of GDM [2-4]. After delivery, GDM usually resolves. However, both mother and child have an increased risk of developing DM2 later in life.In the Netherlands, the prevalence of GDM is estimated between 1-15%, depending on the study population [5]. The highest prevalence is found in non-Dutch women. Because of mi
The 10 Tesla muSR instrument: detector solutions
A. Stoykov,R. Scheuermann,K. Sedlak,J. Rodriguez,U. Greuter,A. Amato
Physics , 2012, DOI: 10.1016/j.phpro.2012.04.028
Abstract: Solutions to the detector system of the High-Field muSR instrument at the Paul Scherrer Institut (PSI) in Switzerland are presented. The strict technical requirements are fulfilled through the application of Geiger-mode Avalanche Photodiodes.
Use of Silicon Photomultipliers in ZnS:6LiF scintillation neutron detectors: signal extraction in presence of high dark count rates
A. Stoykov,J. -B. Mosset,U. Greuter,M. Hildebrandt,N. Schlumpf
Physics , 2014, DOI: 10.1088/1748-0221/9/06/P06015
Abstract: We report on the possibility of using Silicon Photomultipliers (SiPMs) to detect the scintillation light from neutron conversion in ZnS:6LiF scintillators. The light is collected by wavelength-shifting fibers embedded into the scintillator. The difficulty of extracting neutron signals in the presence of high dark count rates of the SiPMs is addressed by applying a dedicated processing algorithm to analyze the temporal distribution of the SiPM pulses. With a single-channel prototype detection unit we demonstrate a very good neutron signal extraction at SiPM dark count rates of about 1 MHz.
Evaluation of two thermal neutron detection units consisting of ZnS/${}^6$LiF scintillating layers with embedded WLS fibers read out with a SiPM
J. -B. Mosset,A. Stoykov,U. Greuter,M. Hildebrandt,N. Schlumpf,H. Van Swygenhoven
Physics , 2014, DOI: 10.1016/j.nima.2014.07.060
Abstract: Two single channel detection units for thermal neutron detection are investigated in a neutron beam. They consist of two ZnS/${}^6$LiF scintillating layers sandwiching an array of WLS fibers. The pattern of this units can be repeated laterally and vertically in order to build up a one dimensional position sensitive multi-channel detector with the needed sensitive surface and with the required neutron absorption probability. The originality of this work arises from the fact that the WLS fibers are read out with SiPMs instead of the traditionally used PMTs or MaPMTs. The signal processing system is based on a photon counting approach. For SiPMs with a dark count rate as high as 0.7 MHz, a trigger efficiency of 80% is achieved together with a system background rate lower than ${10}^{-3}$ Hz and a dead time of 30 $\mu$s. No change of performance is observed for neutron count rates of up to 3.6 kHz.
Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs
J. -B. Mosset,A. Stoykov,U. Greuter,M. Hildebrandt,N. Schlumpf
Physics , 2015,
Abstract: We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC^4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC^4 filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach.
A SiPM-based ZnS:$^6$LiF scintillation neutron detector
A. Stoykov,J. -B. Mosset,U. Greuter,M. Hildebrandt,N. Schlumpf
Physics , 2014, DOI: 10.1016/j.nima.2015.01.076
Abstract: In the work presented here we built and evaluated a single-channel neutron detection unit consisting of a ZnS:$^6$LiF scintillator with embedded WLS fibers readout by a SiPM. The unit has a sensitive volume of 2.4 x 2.8 x 50 mm$^3$; 12 WLS fibers of diameter 0.25 mm are uniformly distributed over this volume and are coupled to a 1 x 1 mm$^2$ active area SiPM. We report the following performance parameters: neutron detection efficiency $\sim 65\,$% at $1.2\,\AA$, background count rate $< 10^{-3}$ Hz, gamma-sensitivity with $^{60}$Co source $< 10^{-6}$, dead time $\sim 20\,\mu$s, multi-count ratio $< 1\,$%. All these parameters were achieved up to the SiPM dark count rate of $\sim 2\,$MHz. We consider such detection unit as an elementary building block for realization of one-dimensional multichannel detectors for applications in the neutron scattering experimental technique. The dimensions of the unit and the number of embedded fibers can be varied to meet the specific application requirements. The upper limit of $\sim 2\,$MHz on the SiPM dark count rate allows to use SiPMs with larger active areas if required.
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