QUANTUM CASCADE LASER: from 3 to 26 mum

Absorption spectroscopy of gases and liquids is amongst the most widely used methods to measure molecular concentrations. It is used in various fields, amongst them are industrial leak testing, medical analysis and surgery, process control and monitoring. Trace gas analysis of low-mass molecules is preferably performed in the mid-IR wavelength region, where the line strength for many molecules are high. With the QCL, invented in 1994, this spectral range has a laser source that delivers sufficient output power in continuous-wave operation. The semiconductor laser is robust and operates in a wide temperature range. This work is dedicated to explore the capabilities of QCLs and improve their performance in the wavelength region from 3 to 26 mum. Our active region simulations are based on a Density Matrix model. The choice of basis wavefunctions is verified and a method to find the optimal injection barrier is presented. The influence of different interface roughness models is discussed. Our model agrees well with the full quantum Non-Equilibrium Green’s Function model and with experiments. In this thesis we explore the short wavelength boundary of QCLs. Lasing emission around 3.3 mum requires highly strained active region material. We investigate in detail active region designs, growth optimization, the impact of intervalley scattering and interface roughness. We present a device emitting at 3.4 mum with dissipation values of only 250 mW and threshold currents as low as 16 mA in pulsed operation. A boxcar experiment with a 5.6 ms long pulse shows stable spectral behaviour of DFB devices, an important requirement for spectroscopic applications. We perform genetic optimizations of devices in the range from 4 to 26 mum and investigate active region design parameters. The optimizations are performed on ”seed” designs of published devices and designs from our own group. The current record design in wallplug efficiency for 9 mum is optimized. The design was extracted from literature and processed along with the optimized structure. Comparing the measurements, we improve the slope efficiency from 1.9 to 2.5 W/A, the wallplug efficiency from 9 to 12 % and the dynamical range from 1.5 to 2.1. For all optimizations, the seed and optimized structures are compared, resulting in some common strategies for optimization. The active region designs are explored experimentally as single stacks and broadband designs. Heterogeneous stacking is discussed and application examples for DFB, external cavity and comb operation are shown. An attempt for spectral coverage of a full octave is presented. We show laser emission spanning from 1090 to 1960 cm-1 at 80 K

An online programme to reduce depression in patients with multiple sclerosis: a randomised controlled trial

Summary Background With a lifetime risk for major depressive disorder of up to 50%, depression is a common comorbidity in multiple sclerosis but remains widely underdiagnosed and untreated. We investigated the potential of a fully automated, internet-based, cognitive behavioural therapy programme, Deprexis, to reduce depressive symptoms in patients with multiple sclerosis. Methods For this randomised controlled trial, we recruited patients from an outpatient clinic in Hamburg, Germany. Patients aged 18–65 years were eligible for inclusion if they had multiple sclerosis and self-reported depressive symptoms. By use of a computer-generated randomisation sequence, we allocated 90 patients (1:1; no blocking or stratification) to either the intervention group or a waitlist control group for 9 weeks. The primary endpoint was the Beck Depression Inventory (BDI), as assessed by an intention-to-treat analysis. This trial is registered with ClinicalTrials.gov, number NCT01663649. Findings 71 patients completed the trial: 35 patients in the intervention group and 36 patients in the control group. During the intervention, BDI scores decreased in the Deprexis group and increased in the control group, yielding a positive effect of Deprexis relative to the waitlist group (mean group difference –4·02 points [95% CI –7·26 to –0·79], p=0·015, effect size d=0·53). Worsening of depressive symptoms from below to above the clinical cutoff (BDI >13) occurred in three (7%) of 45 patients in the control group and no patients in the Deprexis group. We noted no adverse events with respect to new occurrence of suicidal ideation during the trial. Interpretation Psychological online-intervention programmes could be suitable for patients with multiple sclerosis who are unable to regularly attend therapeutic sessions because of mobility impairments. Funding European Union and the Deutsche Forschungsgemeinschaft

Intraoperative endoluminal pyloromyotomy for reduction of delayed gastric emptying after pylorus preserving partial pancreaticoduodenectomy (PORRIDGE trial): study protocol for a randomised controlled trial

BACKGROUND: Pylorus-preserving pancreaticoduodenectomy (ppPD) is a standard surgical procedure for the treatment of resectable neoplasms of the periampullary region. One of the most common postoperative complications after ppPD is delayed gastric emptying (DGE) which reduces quality of life, prevents a timely return to a solid oral diet and prolongs the length of hospital stay. In a retrospective analysis, intraoperative endoluminal pyloromyotomy was associated with a reduced rate of DGE. The aim of this study is to investigate the effect of intraoperative endoluminal pyloromyotomy on postoperative DGE after ppPD in a randomised and controlled setting. METHODS: This randomised trial features parallel group design with a 1:1 allocation ratio and a superiority hypothesis. Patients with a minimum age of 18 years and an indication for ppPD are eligible to participate in this study and will be randomised intraoperatively to receive either endoluminal pyloromyotomy or atraumatic stretching of the pylorus. The sample size calculation (n=64 per study arm) is based on retrospective data. The primary endpoint is the rate of DGE within 30 days. Secondary endpoints are quality of life, operation time, estimated blood loss, length of hospital stay, morbidity and mortality. DISCUSSION: DGE after ppPD is a common complication with an incomplete understood aetiology. Prevention of DGE could improve outcomes and enhance quality of life after one of the most common procedures in pancreatic surgery. This trial will expand the existing evidence on intraoperative pyloromyotomy, and the results will provide additional data on a simple surgical technique that could reduce the incidence of postoperative DGE. TRIAL REGISTRATION: German Clinical Trials RegisterDRKS00013503. Registered on 27 December 2017

Etiology, risk factors and sex differences in ischemic stroke in the Ludwigshafen stroke study, a population-based stroke registry

Background: Stroke etiology in ischemic stroke guides preventive measures and etiological stroke subgroups may show considerable differences between both sexes. In a population-based stroke registry we analyzed etiological subgroups of ischemic stroke and calculated sex-specific incidence and mortality rates. Methods: The Ludwigshafen Stroke Study is a prospective ongoing population-based stroke registry. Multiple overlapping methods of case ascertainment were used to identify all patients with incident stroke or transient ischemic attack. Modified TOAST ( Trial of Org 10172 in Acute Stroke Treatment) criteria were applied for subgroup analysis in ischemic stroke. Results: Out of 626 patients with first-ever ischemic stroke in 2006 and 2007, women (n = 327) were older (73.5 8 12.6 years) than men (n = 299; 69.7 8 11.5 years; p < 0.001). The age-adjusted incidence rate of ischemic stroke was significantly higher in men (1.37; 95% CI 1.20–1.56) than in women (1.12; 95% CI 0.97–1.29; p = 0.04). Cardioembolism (n = 219; 35.0%), smallartery occlusion (n = 164; 26.2%), large-artery atherosclerosis (n = 98; 15.7%) and ‘probable atherothrombotic stroke’ (n = 84; 13.4%) were common subgroups of ischemic stroke. Stroke due to large-artery atherosclerosis (p = 0.025), current smoking (p = 0.008), history of smoking (p 85 years) was detected. Conclusions: Cardioembolism is the main source for ischemic stroke in our population. Etiology of ischemic stroke differs between sexes, with large-artery atherosclerotic stroke and associated diseases (coronary artery disease and peripheral artery disease) being more common in men

Methodological concepts for integrated assessment of agricultural and environmental policies in SEAMLESS-IF

Agricultural and Food Policy, Environmental Economics and Policy, Farm Management, Land Economics/Use,

Multisite Evaluation and Validation of a Sensitive Diagnostic and Screening System for Spinal Muscular Atrophy that Reports SMN1 and SMN2 Copy Number, along with Disease Modifier and Gene Duplication Variants

Spinal muscular atrophy is a severe autosomal recessive disease caused by disruptions in the SMN1 gene. The nearly identical SMN2 gene copy number is associated with disease severity. SMN1 duplication markers, such as c.*3+80T>G and c.*211_*212del, can assess residual carrier risk. An SMN2 disease modifier (c.859G>C) can help inform prognostic outcomes. The emergence of multiple precision gene therapies for spinal muscular atrophy requires accurate and rapid detection of SMN1 and SMN2 copy numbers to enable early treatment and optimal patient outcomes. We developed and evaluated a singletube PCR/capillary electrophoresis assay system that quantifies SMN1/2 copy numbers and genotypes three additional clinically relevant variants. Analytical validation was performed with human cell lines and whole blood representing varying SMN1/2 copies on four capillary electrophoresis instrument models. In addition, four independent laboratories used the assay to test 468 residual clinical genomic DNA samples. The results were >98.3% concordant with consensus SMN1/2 exon 7 copy numbers, determined using multiplex ligation-dependent probe amplification and droplet digital PCR, and were 100% concordant with Sanger sequencing for the three variants. Furthermore, copy number values were 98.6% (SMN1) and 97.1% (SMN2) concordant to each laboratory's own reference results. (J Mol Diag

Approach for Predicting Production Scenarios Focused on Cross Impact Analysis

AbstractOne of the most consistent challenges in business is anticipating what the future holds and what impact it may have on current production systems. The scenario technique is a well-established method for developing and forecasting multiple future development paths for companies. However, this method is mostly employed to develop and to support strategic long-term decisions. The core idea of the approach introduced in this paper is to convey the future impact of today's decisions on production systems to employees involved in production planning processes. With the help of immersive visualization, performed in virtual reality (VR) systems, planning participants can perceive how the factory must adapt to fit future demands.In this paper, the focus is on the fourth phase of the scenario technique – so called scenario development – and, in particular, the cross impact analysis. With this methodology, the interrelations, or cross impacts of the different basic elements are determined. The cross impact analysis results serve as a basis for the development of a standardized tool that can be used to create probable production scenarios out of given production systems. This standardized tool will facilitate the usage of the scenario technique for factory planning projects, as it focuses the immense diversity of future uncertainties companies are faced with on the factory level

Exoplanet Diversity in the Era of Space-based Direct Imaging Missions

This whitepaper discusses the diversity of exoplanets that could be detected by future observations, so that comparative exoplanetology can be performed in the upcoming era of large space-based flagship missions. The primary focus will be on characterizing Earth-like worlds around Sun-like stars. However, we will also be able to characterize companion planets in the system simultaneously. This will not only provide a contextual picture with regards to our Solar system, but also presents a unique opportunity to observe size dependent planetary atmospheres at different orbital distances. We propose a preliminary scheme based on chemical behavior of gases and condensates in a planet's atmosphere that classifies them with respect to planetary radius and incident stellar flux.Comment: A white paper submitted to the National Academy of Sciences Exoplanet Science Strateg