Enhancing the optical excitation efficiency of a single self-assembled quantum dot with a plasmonic nanoantenna

We demonstrate how the controlled positioning of a plasmonic nanoparticle modifies the photoluminescence of a single epitaxial GaAs quantum dot. The antenna particle leads to an increase of the luminescence intensity by about a factor of eight. Spectrally and temporally resolved photoluminescence measurements prove an increase of the quantum dot's excitation rate. The combination of stable epitaxial quantum emitters and plasmonic nanostructures promises to be highly beneficial for nanoscience and quantum optics.Comment: 5 pages, 4 figure

Solving the Ghost-Gluon System of Yang-Mills Theory on GPUs

We solve the ghost-gluon system of Yang-Mills theory using Graphics Processing Units (GPUs). Working in Landau gauge, we use the Dyson-Schwinger formalism for the mathematical description as this approach is well-suited to directly benefit from the computing power of the GPUs. With the help of a Chebyshev expansion for the dressing functions and a subsequent appliance of a Newton-Raphson method, the non-linear system of coupled integral equations is linearized. The resulting Newton matrix is generated in parallel using OpenMPI and CUDA(TM). Our results show, that it is possible to cut down the run time by two orders of magnitude as compared to a sequential version of the code. This makes the proposed techniques well-suited for Dyson-Schwinger calculations on more complicated systems where the Yang-Mills sector of QCD serves as a starting point. In addition, the computation of Schwinger functions using GPU devices is studied.Comment: 19 pages, 7 figures, additional figure added, dependence on block-size is investigated in more detail, version accepted by CP

Effects of impurities and vortices on the low-energy spin excitations in high-Tc materials

We review a theoretical scenario for the origin of the spin-glass phase of underdoped cuprate materials. In particular it is shown how disorder in a correlated d-wave superconductor generates a magnetic phase by inducing local droplets of antiferromagnetic order which eventually merge and form a quasi-long range ordered state. When correlations are sufficiently strong, disorder is unimportant for the generation of static magnetism but plays an additional role of pinning disordered stripe configurations. We calculate the spin excitations in a disordered spin-density wave phase, and show how disorder and/or applied magnetic fields lead to a slowing down of the dynamical spin fluctuations in agreement with neutron scattering and muon spin rotation (muSR) experiments.Comment: 4 pages, 3 figures, submitted for SNS2010 conference proceeding

Mental health literacy: a cross-cultural approach to knowledge and beliefs about depression, schizophrenia and generalized anxiety disorder

Many families worldwide have at least one member with a behavioral or mental disorder, and yet the majority of the public fails to correctly recognize symptoms of mental illness. Previous research has found that Mental Health Literacy (MHL)—the knowledge and positive beliefs about mental disorders—tends to be higher in European and North American cultures, compared to Asian and African cultures. Nonetheless quantitative research examining the variables that explain this cultural difference remains limited. The purpose of our study was fourfold: (a) to validate measures of MHL cross-culturally, (b) to examine the MHL model quantitatively, (c) to investigate cultural differences in the MHL model, and (d) to examine collectivism as a predictor of MHL. We validated measures of MHL in European American and Indian samples. The results lend strong quantitative support to the MHL model. Recognition of symptoms of mental illness was a central variable: greater recognition predicted greater endorsement of social causes of mental illness and endorsement of professional help-seeking as well as lesser endorsement of lay help-seeking. The MHL model also showed an overwhelming cultural difference; namely, lay help-seeking beliefs played a central role in the Indian sample, and a negligible role in the European American sample. Further, collectivism was positively associated with causal beliefs of mental illness in the European American sample, and with lay help-seeking beliefs in the Indian sample. These findings demonstrate the importance of understanding cultural differences in beliefs about mental illness, particularly in relation to help-seeking beliefs

The brain's response to pleasant touch: an EEG investigation of tactile caressing

Somatosensation as a proximal sense can have a strong impact on our attitude toward physical objects and other human beings. However, relatively little is known about how hedonic valence of touch is processed at the cortical level. Here we investigated the electrophysiological correlates of affective tactile sensation during caressing of the right forearm with pleasant and unpleasant textile fabrics. We show dissociation between more physically driven differential brain responses to the different fabrics in early somatosensory cortex - the well-known mu-suppression (10-20 Hz) - and a beta-band response (25-30 Hz) in presumably higher-order somatosensory areas in the right hemisphere that correlated well with the subjective valence of tactile caressing. Importantly, when using single trial classification techniques, beta-power significantly distinguished between pleasant and unpleasant stimulation on a single trial basis with high accuracy. Our results therefore suggest a dissociation of the sensory and affective aspects of touch in the somatosensory system and may provide features that may be used for single trial decoding of affective mental states from simple electroencephalographic measurements

Search for Diboson resonances in 8 tev and 13 tev proton-proton collisions at the large hadron collider with the atlas detector

This thesis documents two searches for Diboson Resonances which were performed using data collected in 2012, 2015 and 2016 by the ATLAS detector at the Large Hadron Collider. Three benchmark models are tested: a model predicting the existence of a new heavy scalar singlet, a simplified model predicting a heavy vector-boson triplet (V ′), and a bulk Randall-Sundrum model with a heavy spin-2 graviton (G∗). Neither of these searches found evidence of any resonance, and exclusion limits are set on σ(pp → V ′) and σ(pp → G∗). For the 2012 ATLAS data, searches are performed for the G∗ and the W′. The sample corresponds to an integrated luminosity of 20.3 fb−1 proton-proton collisions with a center of mass energy √s = 8 TeV. This search looks for the decay channels G∗ → WW → lνjj and W′ → WZ → lνjj. No evidence for resonant diboson production is observed, and resonance masses below 760 GeV and 1490 GeV are excluded at 95% confidence level for the spin-2 Randall–Sundrum bulk graviton G∗ and the spin-1 extended gauge model W′ boson respectively. For the 2015 and 2016 ATLAS data, searches are performed for the G∗ and the V ′ and a heavy scalar. The sample corresponds to an integrated luminosity of 36.1 fb−1 proton-proton collisions with a center of mass energy √s = 13 TeV. This search looks for the decay channels G∗ → V V , scalar → V V and V ′ → V V/V H/dilepton. The V V and V H dibosons then decay into qqqq, ννqq, lνqq, llqq, lνlν, llνν, lνll, llll, qqbb, ννbb, lνbb, or llbb which are all combined (14 channels). No evidence for resonant diboson production is observed, and resonance masses below 2300 GeV are excluded at 95% confidence level for the spin-2 Randall–Sundrum bulk graviton G∗. Resonance masses below 5500 GeV and 4500 GeV are excluded at 95% confidence level for the heavy vector triplet in a weakly coupled scenario and a strongly coupled scenario respectively. No limits are extracted for the heavy scalar

Towards Operational Research Infrastructures with FAIR Data and Services

Environmental research infrastructures aim to provide scientists with facilities, resources and services to enable scientists to effectively perform advanced research. When addressing societal challenges such as climate change and pollution, scientists usually need data, models and methods from different domains to tackle the complexity of the complete environmental system. Research infrastructures are thus required to enable all data, including services, products, and virtual research environments is FAIR for research communities: Findable, Accessible, Interoperable and Reusable. In this last chapter, we conclude and identify future challenges in research infrastructure operation, user support, interoperability, and future evolution

Highly efficient nonrigid motion-corrected 3D whole-heart coronary vessel wall imaging

PURPOSE: To develop a respiratory motion correction framework to accelerate free-breathing three-dimensional (3D) whole-heart coronary lumen and coronary vessel wall MRI.METHODS: We developed a 3D flow-independent approach for vessel wall imaging based on the subtraction of data with and without T2-preparation prepulses acquired interleaved with image navigators. The proposed method corrects both datasets to the same respiratory position using beat-to-beat translation and bin-to-bin nonrigid corrections, producing coregistered, motion-corrected coronary lumen and coronary vessel wall images. The proposed method was studied in 10 healthy subjects and was compared with beat-to-beat translational correction (TC) and no motion correction for the left and right coronary arteries. Additionally, the coronary lumen images were compared with a 6-mm diaphragmatic navigator gated and tracked scan.RESULTS: No significant differences (P &gt; 0.01) were found between the proposed method and the gated and tracked scan for coronary lumen, despite an average improvement in scan efficiency to 96% from 59%. Significant differences (P &lt; 0.01) were found in right coronary artery vessel wall thickness, right coronary artery vessel wall sharpness, and vessel wall visual score between the proposed method and TC.CONCLUSION: The feasibility of a highly efficient motion correction framework for simultaneous whole-heart coronary lumen and vessel wall has been demonstrated. Magn Reson Med, 2016. © 2016 Wiley Periodicals, Inc.</p

OpenSimRoot: widening the scope and application of root architectural models

Research Conducted and Rationale: OpenSimRoot is an open sourced, functional- structural plant model and mathematical description of root growth and function. We describe OpenSimRoot and its functionality to broaden the benefits of root modeling to the plant science community. Description: OpenSimRoot is an extended version of SimRoot, established to simulate root system architecture, nutrient acquisition, and plant growth. OpenSimRoot has a plugin, modular infrastructure, coupling single plant and crop stands to soil nutrient, and water transport models. It estimates the value of root traits for water and nutrient acquisition in environments and plant species. Key results and unique features: The flexible OpenSimRoot design allows upscaling from root anatomy to plant community to estimate 1) resource costs of developmental and anatomical traits, 2) trait synergisms, 3) (inter species) root competition. OpenSimRoot can model 3D images from MRI and X-ray CT of roots in soil. New modules include: 1) soil water dependent water uptake and xylem flow, 2) tiller formation, 3) evapotranspiration, 4) simultaneous simulation of mobile solutes, 5) mesh refinement, and 6) root growth plasticity. Conclusion: OpenSimRoot integrates plant phenotypic data with environmental metadata to support experimental designs and gain mechanistic understanding at system scales