303 research outputs found

    Lasing at the band edges of plasmonic lattices

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    We report room temperature lasing in two-dimensional diffractive lattices of silver and gold plasmon particle arrays embedded in a dye-doped polymer that acts both as waveguide and gain medium. As compared to conventional dielectric distributed feedback lasers, a central question is how the underlying band structure from which lasing emerges is modified by both the much stronger scattering and the disadvantageous loss of metal. We use spectrally resolved back-focal plane imaging to measure the wavelength- and angle dependence of emission below and above threshold, thereby mapping the band structure. We find that for silver particles, the band structure is strongly modified compared to dielectric reference DFB lasers, since the strong scattering gives large stop gaps. In contrast, gold particles scatter weakly and absorb strongly, so that thresholds are higher, but the band structure is not strongly modified. The experimental findings are supported by finite element and fourier modal method calculations of the single particle scattering strength and lattice extinction.Comment: 10 pages, 8 figure

    Visual Field Reconstruction in Hemianopia Using fMRI Based Mapping Techniques

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    PURPOSE: A stroke that includes the primary visual cortex unilaterally leads to a loss of visual field (VF) representation in the hemifield contralateral to the damage. While behavioral procedures for measuring the VF, such as perimetry, may indicate that a patient cannot see in a particular area, detailed psychophysical testing often detects the ability to perform detection or discrimination of visual stimuli (“blindsight”). The aim of this study was to determine whether functional magnetic resonance imaging (fMRI) could be used to determine whether perimetrically blind regions of the VF were still represented in VF maps reconstructed on the basis of visually evoked neural activity. METHODS: Thirteen patients with hemianopia and nine control participants were scanned using 3T MRI while presented with visual stimulation. Two runs of a dynamic “wedge and ring” mapping stimulus, totaling approximately 10 min, were performed while participants fixated centrally. Two different analysis approaches were taken: the conventional population receptive field (pRF) analysis and micro-probing (MP). The latter is a variant of the former that makes fewer assumptions when modeling the visually evoked neural activity. Both methods were used to reconstruct the VF by projecting modeled activity back onto the VF. Following a normalization step, these “coverage maps” can be compared to the VF sensitivity plots obtained using perimetry. RESULTS: While both fMRI-based approaches revealed regions of neural activity within the perimetrically “blind” sections of the VF, the MP approach uncovered more voxels in the lesioned hemisphere in which a modest degree of visual sensitivity was retained. Furthermore, MP-based analysis indicated that both early (V1/V2) and extrastriate visual areas contributed equally to the retained sensitivity in both patients and controls. CONCLUSION: In hemianopic patients, fMRI-based approaches for reconstructing the VF can pick up activity in perimetrically blind regions of the VF. Such regions of the VF may be particularly amenable for rehabilitation to regain visual function. Compared to conventional pRF modeling, MP reveals more voxels with retained visual sensitivity, suggesting it is a more sensitive approach for VF reconstruction

    Разработка электроэнцефалографа на наносенсорах для исследования мозга человека в расширенном диапазоне частот

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    В выпускной квалификационной работе проведен анализ методов исследования мозга человека. Выбрана электроэнцефалография в качестве основного метода регистрации биоэлектрической активности с помощью наносенсоров. Разработан электроэнцефалограф для исследования мозга человека в расширенном диапазоне частот (0-10000 Гц), позволяющий получить дополнительную информацию о регистрируемых биопотенциалах и ритмах ЭЭГ. Проведено исследование для оценки психоэмоционального состояния человека и исследование для подтверждения возможности использования разработанного электроэнцефалографа в качестве электронейромиографа.IIn the final qualifying work, an analysis of methods of studying the human brain was carried out. Electroencephalography was chosen as the main method for recording bioelectrical activity with nanosensors. The developer is an electroencephalograph for studying the human brain in the extended frequency range (0-10000 Hz), which allows obtaining additional information on the detected bioelectric potentials and EEG rhythms. A study was conducted to assess the psychoemotional state of a person and study to confirm the possibility of using the developed electroencephalograph as an electroneuromiograph

    Rank concordance of polygenic indices

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    Polygenic indices (PGIs) are increasingly used to identify individuals at risk of developing disease and are advocated as screening tools for personalized medicine and education. Here we empirically assess rank concordance between PGIs created with different construction methods and discovery samples, focusing on cardiovascular disease and educational attainment. We find Spearman rank correlations between 0.17 and 0.93 for cardiovascular disease, and 0.40 and 0.83 for educational attainment, indicating highly unstable rankings across different PGIs for the same trait. Potential consequences for personalized medicine and gene–environment (G × E) interplay are illustrated using data from the UK Biobank. Simulations show how rank discordance mainly derives from a limited discovery sample size and reveal a tight link between the explained variance of a PGI and its ranking precision. We conclude that PGI-based ranking is highly dependent on PGI choice, such that current PGIs do not have the desired precision to be used routinely for personalized intervention.</p

    First identification of large electric monopole strength in well-deformed rare earth nuclei

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    Excited states in the well-deformed rare earth isotopes 154^{154}Sm and 166^{166}Er were populated via ``safe'' Coulomb excitation at the Munich MLL Tandem accelerator. Conversion electrons were registered in a cooled Si(Li) detector in conjunction with a magnetic transport and filter system, the Mini-Orange spectrometer. For the first excited 0+0^+ state in 154^{154}Sm at 1099 keV a large value of the monopole strength for the transition to the ground state of ρ2(E0;02+0g+)=96(42)103\rho^2(\text{E0}; 0^+_2 \to 0^+_\text{g}) = 96(42)\cdot 10^{-3} could be extracted. This confirms the interpretation of the lowest excited 0+0^+ state in 154^{154}Sm as the collective β\beta-vibrational excitation of the ground state. In 166^{166}Er the measured large electric monopole strength of ρ2(E0;04+01+)=127(60)103\rho^2(\text{E0}; 0^+_4 \to 0^+_1) = 127(60)\cdot 10^{-3} clearly identifies the 04+0_4^+ state at 1934 keV to be the β\beta-vibrational excitation of the ground state.Comment: submitted to Physics Letters

    Intraperitoneal bevacizumab for control of malignant ascites due to advanced-stage gastrointestinal cancers: A multicentre double-blind, placebo-controlled phase II study - AIO SUP-0108

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    PURPOSE: Malignant ascites is debilitating for patients with advanced cancer. As shown previously, tumour cell production of vascular endothelial growth factor might be a major cause of the formation of malignant ascites. Intraperitoneal bevacizumab could therefore be an option for symptom control in refractory ascites. PATIENTS AND METHODS: Patients with advanced gastrointestinal cancer and malignant ascites who had undergone paracentesis at least twice within the past 4 weeks were randomly assigned in a 2:1 ratio to intraperitoneal bevacizumab (400 mg absolute) or placebo after paracentesis. During the 8-week treatment period, a minimum interval of 14 d was kept between the applications of the study drug. Primary end-point was paracentesis-free survival (ParFS). RESULTS: Fifty-three patients (median age 63 years) were randomised. Forty-nine patients received at least one study drug application and qualified for the main analysis. The proportion of patients with at least one common toxicity criteria grade III-V event was similar with 20/33 (61%) on bevacizumab and 11/16 (69%) on placebo. Median ParFS was 14 d (95% confidence interval [CI]: 11-17) in the bevacizumab arm and 10.5 d (95% CI: 7-21) on placebo (hazard ratio 0.74, 95% CI: 0.40-1.37; P = 0.16). The longest paracentesis-free period was 19 d on bevacizumab (range 6-66 d) and 17.5 d in the placebo arm (range 4-42) (P = 0.85). Median overall survival was 64 d (95% CI: 45-103) on bevacizumab compared to 31.5 d (95% CI: 20-117) on placebo (P = 0.31). CONCLUSION: Intraperitoneal bevacizumab was well tolerated. Overall, treatment did not result in a significantly better symptom control of malignant ascites. However, patients defined by specific immune characteristics may benefit

    LAS BATALLAS FESTIVAS DE ESPANA

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    Serving individual customer needs at reasonable prices can be a profitable target market in high-wage countries. The dilemma between scale and scope-oriented production is one major research topic within the Cluster of Excellence "Integrative Production Technology for High-Wage Countries" at the RWTH Aachen University. One main objective of this project is to bridge the existing gap between individual manufacturing and mass production. Modularization is a widely accepted approach in tool-based manufacturing processes. In this paper, we propose a flexible design methodology for modular tools and dies. The methodology will assist the design engineer in setting up a series of modularized tools in a conceptually closed manner. The described methodology covers modularization in a broad sense, i.e. it includes hardware modularization as well as modularization of the construction process. The methodology consists of three phases: initiation, analysis and design phase
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