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Objective Low-dose computed tomography (LDCT) lung cancer screening is endorsed by US guidelines and has recently been shown effective in a large European randomized controlled trial. Nevertheless, actual realization of a lung cancer screening program is challenging and depends on country-specific factors. This pilot study aimed to evaluate implementation, execution, and performance of LDCT lung cancer screening in Switzerland. Methods Since October 2018, asymptomatic participants aged 55–74 years with more than 30 pack-years smoking history were enrolled at a tertiary hospital in Switzerland. Participants with history of lung cancer, major (palliative) health problems or those that had a thorax CT scan 18 months prior to enrollment were excluded. First, we evaluated lung cancer risk according to NLST guidelines. Second, we estimated lung cancer risk using the PLCOm2012 model risk calculator with threshold of 5%. Lung nodules were assessed according to Lung-RADS (Version 1.1. 2019). Participants were recruited through flyers, a newspaper article and pulmonary specialists. Screening consisted of one LDCT-scan, follow-up was recommended for suspicious nodules only. LDCT assessment was performed by two radiologists, one of them a board certified chest radiologist. Enrollment and follow-up are currently ongoing. Results To date, 75 participants (25 (33%) females) with a median age of 62 years (interquartile range [IQR] 56–67 years) were included. Median number of pack years smoked was 49 (IQR 41–58 pack years). Median PLCOm2012 6-year lung cancer probability was 2.7% (IQR 2.6–2.9%), 19 (26%) participants had stopped smoking before enrollment. 6 participants required follow up imaging of suspect nodules, resulting in a recall rate of 8%. At baseline, lung cancer was found in 2 (2.7%, one squamous cell (stage IIIA) and one adenocarcinoma (stage IV)) participants. Conclusion In this Swiss LDCT lung cancer screening pilot study using modified inclusion criteria, 2.7% were diagnosed with lung cancer to date.

In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS) to a preconcentration unit, called TRace gas EXtractor (TREX). This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, μmole/mole) methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on replicate measurements of compressed air during a two-week intercomparison campaign, the repeatability of the TREX-QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass-spectrometry (IRMS) based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. Thus, the intercomparison also reveals the need for reference air samples with accurately determined isotopic composition of CH4 to further improve the interlaboratory compatibility.

We review the significant progress made in the development of nitride laser diodes by molecular beam epitaxy (MBE). We report on our recent result of room temperature continuous-wave operation of InGaN quantum well laser diodes grown by MBE. Ridge waveguide lasers fabricated on freestanding GaN substrates have a continuous-wave threshold current of 125 mA, corresponding to a threshold current density of 5.7 kA cm–2. The lasers have a threshold voltage of 8.6 V and a lifetime of several minutes. We outline the further technical challenges associated with demonstrating lifetimes of several thousand hours and present an assessment of the potential of MBE as a growth method for commercial quality nitride optoelectronic devices. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The latest results from MBE-grown InGaN multiple quantum well laser diodes and light emitting diodes are presented. The laser diodes were grown on free-standing n-type GaN substrates and fabricated into index guided structures with a ridge width of 3.6 and 1000 μm cavity length. Laser operation occurred at room temperature under pulsed current injection up to a 10% duty cycle. A typical best threshold current density of 7 kA cm−2 and as operating voltage of 10 V was achieved. Light emitting diodes were grown on silicon-doped GaN template substrates and fabricated into 1 mm2 header mounted, non-encapsulated chips. At 20 mA dc current operation, an output power of 3 mW was measured. A peak power of 10 mW was achieved at 90 mA before thermal rollover occurred. The lasers and light emitting diodes emitted in the wavelength range 390–410 nm.

We report progress in the development of InGaN multiple quantum well laser diodes grown by MBE. Lasers were grown by gas-source MBE using ammonia as the source of nitrogen. Devices were grown on both GaN template substrates with dry-etched laser facets, and on low dislocation density free-standing GaN substrates where cleaved laser facets are possible. We have achieved a minimum threshold current density of ∼11 kA cm -2 on templates and ∼7 kA cm -2 on free-standing GaN. On GaN substrates we have achieved room temperature operation with a pulsed duty cycle of 10%. Further optimisation of the device is required to reduce thermal effects and achieve CW operation.

A wet effluent denuder - aerosol collector (WEDD/AC) system coupled to ion chromatography for the measurement of atmospheric HONO, HNO3 and particulate nitrite, nitrate and sulfate is described. Several experiments were performed to outline its performance. The main features are low detection limits and a fast response to concentration changes which enables measurements with high time resolution. In contrast to highly soluble gases, the collection efficiency of less soluble gases is shown to depend on the Henry’s law constant rather than on the uptake kinetics. To improve the collection efficiency for HONO under simultaneous presence of acidifying gases, NaHCO3 was added to the effluent solution. The system was tested in a field campaign in the suburban area of Zurich, Switzerland. Elevated concentrations of nitrous acid up to 3.2 ppb were detected during the measurement campaign. The diurnal variation of the HONO to NO2 ratio clearly points to a fast and persistent process producing HONO in the atmosphere. The correlation with NOx and black carbon suggests a heterogeneous formation of HONO, and is consistent with a reaction on soot aerosol particle surfaces postulated from previous laboratory results.

History and admission findings A 54-year-old farmer with moderate mitral valve regurgitation was admitted to hospital because of suspected infective endocarditis. Examinations Echocardiography revealed a large mitral valve vegetation as the source of multifocal septic emboli to the central nervous system, spleen, mesenteric and femoro-popliteal arteries, eyes, and kidneys. Eventually an embolus removed from the femoro-popliteal artery and vegetations on the replaced mitral valve grew C. albicans. Therapy Despite treatment with amphotericin B and valve replacement the patient died of septicemia due to E. coli. Conclusion Endocarditis due to C. albicans is commonly associated with severe complications. Diagnosis of this rare disease is often delayed because of negative blood cultures. Large cardiac vegetations and embolization of major arterial vessels should raise the suspicion of fungal endocarditis.

Long-term time series of the atmospheric composition are essential for environmental research and thus require compatible, multi-decadal monitoring activities. However, the current data quality objectives of the World Meteorological Organization (WMO) for carbon monoxide (CO) in the atmosphere are very challenging to meet with the measurement techniques that have been used until recently. During the past few years, new spectroscopic techniques came on the market with promising properties for trace gas analytics. The current study compares three instruments that are recently commercially available (since 2011) with the up to now best available technique (vacuum UV fluorescence) and provides a link to previous comparison studies. The instruments were investigated for their performance regarding repeatability, reproducibility, drift, temperature dependence, water vapour interference and linearity. Finally, all instruments were examined during a short measurement campaign to assess their applicability for long-term field measurements. It could be shown that the new techniques provide a considerably better performance compared to previous techniques, although some issues such as temperature influence and cross sensitivities need further attention.

We report material gain measurements of bulk 1.55 μm InGaAsP/InP performed at constant temperature and carried out over a large range of carrier densities and a large spectral region. In addition, a polynomial model for the material gain is proposed that not only fits the experimental data well over the whole measured range but also shows stable convergence in simulation tools when carrier densities exceed the usual range. To get reliable parameters for the model we eliminated temperature effects arising from different current biases and performed material-gain measurements over the largest possible carrier density range. The material-gain model realized is used in semiconductor optical amplifier simulation tools.

International audience

Semiconductor nitrides have many applications for optoelectronic devices; particularly, blue-violet laser diodes (LDs) are required for blu-ray optical disc systems. Molecular beam epitaxy (MBE) with its fine control of growth parameters and capability for in-situ growth monitoring is a well-established technique for depositing III-V heterostructures. Indeed, many commercial infrared LDs are grown very successfully by MBE. However, MBE-growth of nitrides is much more difficult, because providing enough nitrogen atoms at the growth surface, sustaining the high growth temperatures as well as finding the right growth parameters have proved to be very challenging. We recently reported the first InGaN LDs by MBE, showing that those problems can be solved in practice as well as demonstrating the capability of MBE to produce high-quality optoelectronic devices. As the efficiency of nitrides depends strongly on the growth process, structural differences of MBE over metal-organic vapor phase epitaxy (MOVPE)-material may also lead to device advantages. Our first InGaN LDs were grown on sapphire templates, with a pulsed room-temperature threshold current-density of 30 kA/cm

InGaN multiple quantum well laser diodes have been fabricated by MBE. Lasers grown on GaN template substrates and on free-standing GaN substrates exhibit a minimum threshold current density of 7 kAcm/sup -2 /at room temperature.

We report on recent results obtained for InGaN multiple quantum well laser diodes grown by ammonia based Molecular Beam Epitaxy. The laser diodes were grown on freestanding GaN substrates and operated at room temperature under pulsed current injection conditions. For devices with improved p-type doping a threshold current density of 6.7kA.cm−2 was measured for a current pulse duration of 200ns and an operating temperature of 3.9°C. A duty cycle up to 50% with a pulsed injection current duration of 500μs was also achieved at 3.9°C.

Results of continuous nitrogen oxide (NO), nitrogen dioxide (NO2), peroxyacetyl nitrate (PAN) and total reactive nitrogen (NOy) measurements along with seasonal field campaigns of nitric acid (HNO3) and particulate nitrate (NO3-) measurements are presented for a two-year period at the high-alpine research station Jungfraujoch (JFJ), 3580 m asl. The NOy mixing ratio and partitioning is shown to strongly depend on meteorological conditions. Knowledge of these meteorological transport processes allows discrimination between undisturbed (i.e. clean) and disturbed (i.e. influenced by regional pollution sources) free tropospheric (FT) conditions at the JFJ. Median NOy concentrations during undisturbed FT periods ranged from 350 pptv (winter, December to February) to 581 pptv (spring, March to April). PAN was found to be the dominant NOy species during spring and summer, whereas NO2 was most abundant during autumn and winter. Particulate nitrate was found to contribute significantly to total NOy during thermally induced vertical transport. Föhn events, synoptical lifting (e.g. fronts) and thermally induced vertical transport resulted in mixing ratios up to 10 times higher at the JFJ compared to undisturbed FT conditions. Furthermore this meteorological variability of the NOy concentration and partitioning often dominated the seasonal variability. As a consequence the use of filters at the JFJ (and other mountainous sites) is crucial for the interpretation of data from such measurement sites. This study presents a further development of meteorological filters for the high-alpine site Jungfraujoch, which could be adapted to other mountainous measurement sites.

The first continuous-wave InGaN multiple quantum well laser diodes grown by molecular beam epitaxy are reported. Ridge waveguide lasers are fabricated on free-standing GaN substrates and operated at room temperature under continuous-wave current injection. For 2.2/spl times/1000 /spl mu/m lasers with highly reflective facet coatings a continuous-wave threshold current of 125 mA is obtained, corresponding to a threshold current density of 5.7 kA cm/sup -2/. The lasers have a threshold voltage of 8.6 V and lase at a wavelength of /spl sim/405 nm for >3 min at 20/spl deg/C.

The highest power InGaN light emitting diodes produced by molecular beam epitaxy are reported. When operated in continuous-wave mode at room temperature, the optical output power of the devices was 3.75 mW at a forward injection current of 20 mA, and the maximum output power was 14.3 mW. The electroluminescence had a peak at 405 nm and a full width half maximum of 15 nm. The electrical characteristics showed a voltage of 4.8 V and a resistance of 31 Ω at a forward injection current of 20 mA.