University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Evolution of an Ensemble of Nanoparticles in a Colloidal Solution: Theoretical Study

Abstract: The evolution of a nanosized particle in colloidal solution has been studied theoretically. The model developed is based on the size dependence of the activation energies of the growth and dissolution processes and takes into account the mass transport dynamics. Using this model, Monte Carlo simulations of the evolution of an ensemble of growing nanoparticles during Ostwald ripening have been performed, and conditions leading to either “focusing” or “defocusing” of the particle size distribution were found. The stationary particle size distribution inherent to the Ostwald ripening process in ensembles of nanoparticles less than 5 nm in radius is narrower and more symmetric than that predicted by the Lifshitz−Slyozov−Wagner theory valid for ensembles of larger (>20 nm in radius) colloidal particles. The growth of nanoparticles in the diffusion-controlled regime results in better final size distributions as compared with those grown in the reaction-controlled regime. The dependence of the particle size dist...

Threshold resummation for squark-antisquark and gluino-pair production at the LHC.

Abstract: We study the effect of soft gluon emission in the hadroproduction of squark-antisquark and gluino-gluino pairs at the next-to-leading logarithmic (NLL) accuracy within the framework of the minimal supersymmetric model. The one-loop soft anomalous dimension matrices controlling the color evolution of the underlying hard-scattering processes are calculated. We present the resummed total cross sections and show numerical results for proton-proton collisions at 14 TeV. For the gluino-pair production, the theoretical uncertainty due to scale variation is reduced to the few-percent level.

Four-Week Prevalence of Mental Disorders in Patients With Cancer Across Major Tumor Entities

Abstract: Purpose To provide the 4-week prevalence estimates of mental disorders in cancer populations. Patients and Methods We enrolled adult patients with cancer from in- and outpatient care facilities, using a proportional stratified random sample based on the nationwide cancer incidence in Germany. Patients who scored 9 or above on the Patient Health Questionnaire (PHQ-9) were administered to the standardized computer-assisted Composite International Diagnostic Interview for mental disorders adapted for cancer patients (CIDI-O). A random sample of those with a PHQ-9 score that was less than 9 were selected for a CIDI-O. Results A total of 5,889 patients were identified, which led to 4,020 participants (a 68.3% response rate); of those, 2,141 patients were interviewed. The 4-week total prevalence for any mental disorder was 31.8% (95% CI, 29.8% to 33.8%); this included any anxiety disorder (11.5%; 95% CI, 10.2% to 12.9%), any adjustment disorder (11.1%; 95% CI, 9.7% to 12.4%), any mood disorder (6.5%; 95% CI, 5....

Continuous-time quantum Monte Carlo method for fermions

Abstract: We present a numerically exact continuous-time quantum Monte Carlo algorithm for fermions with a general interaction nonlocal in space-time The new determinantal grand-canonical scheme is based on a stochastic series expansion for the partition function in the interaction representation The method is particularly applicable for multiband, time-dependent correlations since it does not invoke the Hubbard-Stratonovich transformation The test calculations for exactly solvable models, as well results for the Green function and for the time-dependent susceptibility of the multiband supersymmetric model with a spin-flip interaction are discussed

Negative emissions—Part 1: Research landscape and synthesis

Abstract: With the Paris Agreement's ambition of limiting climate change to well below 2 °C, negative emission technologies (NETs) have moved into the limelight of discussions in climate science and policy. Despite several assessments, the current knowledge on NETs is still diffuse and incomplete, but also growing fast. Here, we synthesize a comprehensive body of NETs literature, using scientometric tools and performing an in-depth assessment of the quantitative and qualitative evidence therein. We clarify the role of NETs in climate change mitigation scenarios, their ethical implications, as well as the challenges involved in bringing the various NETs to the market and scaling them up in time. There are six major findings arising from our assessment: first, keeping warming below 1.5 °C requires the large-scale deployment of NETs, but this dependency can still be kept to a minimum for the 2 °C warming limit. Second, accounting for economic and biophysical limits, we identify relevant potentials for all NETs except ocean fertilization. Third, any single NET is unlikely to sustainably achieve the large NETs deployment observed in many 1.5 °C and 2 °C mitigation scenarios. Yet, portfolios of multiple NETs, each deployed at modest scales, could be invaluable for reaching the climate goals. Fourth, a substantial gap exists between the upscaling and rapid diffusion of NETs implied in scenarios and progress in actual innovation and deployment. If NETs are required at the scales currently discussed, the resulting urgency of implementation is currently neither reflected in science nor policy. Fifth, NETs face severe barriers to implementation and are only weakly incentivized so far. Finally, we identify distinct ethical discourses relevant for NETs, but highlight the need to root them firmly in the available evidence in order to render such discussions relevant in practice.