University of Duisburg-Essen

About: University of Duisburg-Essen is a education organization based out in Essen, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Population & Transplantation. The organization has 16072 authors who have published 39972 publications receiving 1109199 citations.

Quality control and conduct of genome-wide association meta-analyses

Abstract: Rigorous organization and quality control (QC) are necessary to facilitate successful genome-wide association meta-analyses (GWAMAs) of statistics aggregated across multiple genome-wide association studies. This protocol provides guidelines for (i) organizational aspects of GWAMAs, and for (ii) QC at the study file level, the meta-level across studies and the meta-analysis output level. Real-world examples highlight issues experienced and solutions developed by the GIANT Consortium that has conducted meta-analyses including data from 125 studies comprising more than 330,000 individuals. We provide a general protocol for conducting GWAMAs and carrying out QC to minimize errors and to guarantee maximum use of the data. We also include details for the use of a powerful and flexible software package called EasyQC. Precise timings will be greatly influenced by consortium size. For consortia of comparable size to the GIANT Consortium, this protocol takes a minimum of about 10 months to complete.

Efficacy of different types of aerobic exercise in fibromyalgia syndrome: a systematic review and meta-analysis of randomised controlled trials.

Abstract: The efficacy and the optimal type and volume of aerobic exercise (AE) in fibromyalgia syndrome (FMS) are not established. We therefore assessed the efficacy of different types and volumes of AE in FMS. The Cochrane Library, EMBASE, MEDLINE, PsychInfo and SPORTDISCUS (through April 2009) and the reference sections of original studies and systematic reviews on AE in FMS were systematically reviewed. Randomised controlled trials (RCTs) of AE compared with controls (treatment as usual, attention placebo, active therapy) and head-to-head comparisons of different types of AE were included. Two authors independently extracted articles using predefined data fields, including study quality indicators. Twenty-eight RCTs comparing AE with controls and seven RCTs comparing different types of AE with a total of 2,494 patients were reviewed. Effects were summarised using standardised mean differences (95% confidence intervals) by random effect models. AE reduced pain (-0.31 (-0.46, -0.17); P < 0.001), fatigue (-0.22 (-0.38, -0.05); P = 0.009), depressed mood (-0.32 (-0.53, -0.12); P = 0.002) and limitations of health-related quality of life (HRQOL) (-0.40 (-0.60, -0.20); P < 0.001), and improved physical fitness (0.65 (0.38, 0.95); P < 0.001), post treatment. Pain was significantly reduced post treatment by land-based and water-based AE, exercises with slight to moderate intensity and frequency of two or three times per week. Positive effects on depressed mood, HRQOL and physical fitness could be maintained at follow-up. Continuing exercise was associated with positive outcomes at follow-up. Risks of bias analyses did not change the robustness of the results. Few studies reported a detailed exercise protocol, thus limiting subgroup analyses of different types of exercise. An aerobic exercise programme for FMS patients should consist of land-based or water-based exercises with slight to moderate intensity two or three times per week for at least 4 weeks. The patient should be motivated to continue exercise after participating in an exercise programme.

Overall Survival in Patients With Advanced Melanoma Who Received Nivolumab Versus Investigator's Choice Chemotherapy in CheckMate 037: A Randomized, Controlled, Open-Label Phase III Trial.

Abstract: Purpose Until recently, limited options existed for patients with advanced melanoma who experienced disease progression while receiving treatment with ipilimumab. Here, we report the coprimary overall survival (OS) end point of CheckMate 037, which has previously shown that nivolumab resulted in more patients achieving an objective response compared with chemotherapy regimens in ipilimumab-refractory patients with advanced melanoma. Patients and Methods Patients were stratified by programmed death-ligand 1 expression, BRAF status, and best prior cytotoxic T-lymphocyte antigen-4 therapy response, then randomly assigned 2:1 to nivolumab 3 mg/kg intravenously every 2 weeks or investigator's choice chemotherapy (ICC; dacarbazine 1,000 mg/m2 every 3 weeks or carboplatin area under the curve 6 plus paclitaxel 175 mg/m2 every 3 weeks). Patients were treated until they experienced progression or unacceptable toxicity, with follow-up of approximately 2 years. Results Two hundred seventy-two patients were randomly assigned to nivolumab (99% treated) and 133 to ICC (77% treated). More nivolumab-treated patients had brain metastases (20% v 14%) and increased lactate dehydrogenase levels (52% v 38%) at baseline; 41% of patients treated with ICC versus 11% of patients treated with nivolumab received anti-programmed death 1 agents after randomly assigned therapy. Median OS was 16 months for nivolumab versus 14 months for ICC (hazard ratio, 0.95; 95.54% CI, 0.73 to 1.24); median progression-free survival was 3.1 months versus 3.7 months, respectively (hazard ratio, 1.0; 95.1% CI, 0.78 to 1.436). Overall response rate (27% v 10%) and median duration of response (32 months v 13 months) were notably higher for nivolumab versus ICC. Fewer grade 3 and 4 treatment-related adverse events were observed in patients on nivolumab (14% v 34%). Conclusion Nivolumab demonstrated higher, more durable responses but no difference in survival compared with ICC. OS should be interpreted with caution as it was likely impacted by an increased dropout rate before treatment, which led to crossover therapy in the ICC group, and by an increased proportion of patients in the nivolumab group with poor prognostic factors.

Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions

Abstract: Multiple optical harmonic generation—the multiplication of photon energy as a result of nonlinear interaction between light and matter—is a key technology in modern electronics and optoelectronics, because it allows the conversion of optical or electronic signals into signals with much higher frequency, and the generation of frequency combs. Owing to the unique electronic band structure of graphene, which features massless Dirac fermions1–3, it has been repeatedly predicted that optical harmonic generation in graphene should be particularly efficient at the technologically important terahertz frequencies4–6. However, these predictions have yet to be confirmed experimentally under technologically relevant operation conditions. Here we report the generation of terahertz harmonics up to the seventh order in single-layer graphene at room temperature and under ambient conditions, driven by terahertz fields of only tens of kilovolts per centimetre, and with field conversion efficiencies in excess of 10−3, 10−4 and 10−5 for the third, fifth and seventh terahertz harmonics, respectively. These conversion efficiencies are remarkably high, given that the electromagnetic interaction occurs in a single atomic layer. The key to such extremely efficient generation of terahertz high harmonics in graphene is the collective thermal response of its background Dirac electrons to the driving terahertz fields. The terahertz harmonics, generated via hot Dirac fermion dynamics, were observed directly in the time domain as electromagnetic field oscillations at these newly synthesized higher frequencies. The effective nonlinear optical coefficients of graphene for the third, fifth and seventh harmonics exceed the respective nonlinear coefficients of typical solids by 7–18 orders of magnitude7–9. Our results provide a direct pathway to highly efficient terahertz frequency synthesis using the present generation of graphene electronics, which operate at much lower fundamental frequencies of only a few hundreds of gigahertz. Efficient terahertz harmonic generation—challenging but important for ultrahigh-speed optoelectronic technologies—is demonstrated in graphene through a nonlinear process that could potentially be generalized to other materials.

Testing the limits of quantum mechanical superpositions

Abstract: Quantum physics has intrigued scientists and philosophers alike, because it challenges our notions of reality and locality — concepts that we have grown to rely on in our macroscopic world. It is an intriguing open question whether the linearity of quantum mechanics extends into the macroscopic domain. Scientific progress over the past decades inspires hope that this debate may be settled by table-top experiments. Testing the limits of the quantum mechanical description of nature has become a subject of intense experimental interest. Recent advances in investigating macroscopic quantum superpositions are pushing these limits.