375 research outputs found

    Within-subject Intra- and Inter-method consistency of two experimental risk attitude elicitation

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    We compare the consistency of choices in two methods to used elicit risk preferences on an aggregate as well as on an individual level. We asked subjects to choose twice from a list of nine decision between two lotteries, as introduced by Holt and Laury (2002, 2005) alternating with nine decisions using the budget approach introduced by Andreoni and Harbaugh (2009). We find that while on an aggregate (subject pool) level the results are (roughly) consistent, on an individual (within-subject) level, behavior is far from consistent. Within each method as well as across methods we observe low correlations. This again questions the reliability of experimental risk elicitation measures and the ability to use results from such methods to control for the risk aversion of subjects when explaining effects in other experimental games.risk preferences, laboratory experiment, elicitation methods, subject heterogeneity

    Ligand-receptor binding kinetics in surface plasmon resonance cells: A Monte Carlo analysis

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    Surface plasmon resonance (SPR) chips are widely used to measure association and dissociation rates for the binding kinetics between two species of chemicals, e.g., cell receptors and ligands. It is commonly assumed that ligands are spatially well mixed in the SPR region, and hence a mean-field rate equation description is appropriate. This approximation however ignores the spatial fluctuations as well as temporal correlations induced by multiple local rebinding events, which become prominent for slow diffusion rates and high binding affinities. We report detailed Monte Carlo simulations of ligand binding kinetics in an SPR cell subject to laminar flow. We extract the binding and dissociation rates by means of the techniques frequently employed in experimental analysis that are motivated by the mean-field approximation. We find major discrepancies in a wide parameter regime between the thus extracted rates and the known input simulation values. These results underscore the crucial quantitative importance of spatio-temporal correlations in binary reaction kinetics in SPR cell geometries, and demonstrate the failure of a mean-field analysis of SPR cells in the regime of high Damk\"ohler number Da > 0.1, where the spatio-temporal correlations due to diffusive transport and ligand-receptor rebinding events dominate the dynamics of SPR systems.Comment: 21 pages, 9 figure

    Infinite hierarchy of nonlinear Schrödinger equations and their solutions

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    We study the infinite integrable nonlinear Schrödinger equation (NLSE) hierarchy beyond the Lakshmanan-Porsezian-Daniel equation which is a particular (fourth-order) case of the hierarchy. In particular, we present the generalized Lax pair and generalized soliton solutions, plane wave solutions, AB breathers, Kuznetsov-Ma breathers, periodic solutions and rogue wave solutions for this infinite order hierarchy. We find that 'even' order equations in the set affect phase and 'stretching factors' in the solutions, while 'odd' order equations affect the velocities. Hence 'odd' order equation solutions can be real functions, while 'even' order equation solutions are always complex

    High synovial expression of the inhibitory FcγRIIb in rheumatoid arthritis

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    Activating Fc gamma receptors (FcγRs) have been identified as having important roles in the inflammatory joint reaction in rheumatoid arthritis (RA) and murine models of arthritis. However, the role of the inhibitory FcγRIIb in the regulation of the synovial inflammation in RA is less known. Here we have investigated synovial tissue from RA patients using a novel monoclonal antibody (GB3) specific for the FcγRIIb isoform. FcγRIIb was abundantly expressed in synovia of RA patients, in sharp contrast to the absence or weak staining of FcγRIIb in synovial biopsies from healthy volunteers. In addition, the expression of FcγRI, FcγRII and FcγRIII was analyzed in synovia obtained from early and late stages of RA. Compared with healthy synovia, which expressed FcγRII, FcγRIII but not FcγRI, all activating FcγRs were expressed and significantly up-regulated in RA, regardless of disease duration. Macrophages were one of the major cell types in the RA synovium expressing FcγRIIb and the activating FcγRs. Anti-inflammatory treatment with glucocorticoids reduced FcγR expression in arthritic joints, particularly that of FcγRI. This study demonstrates for the first time that RA patients do not fail to up-regulate FcγRIIb upon synovial inflammation, but suggests that the balance between expression of the inhibitory FcγRIIb and activating FcγRs may be in favour of the latter throughout the disease course. Anti-inflammatory drugs that target activating FcγRs may represent valuable therapeutics in this disease

    Glutaconate CoA-transferase from Acidaminococcus fermentans: the crystal structure reveals homology with other CoA-transferases

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    AbstractBackground: Coenzyme A-transferases are a family of enzymes with a diverse substrate specificity and subunit composition. Members of this group of enzymes are found in anaerobic fermenting bacteria, aerobic bacteria and in the mitochondria of humans and other mammals, but so far none have been crystallized. A defect in the human gene encoding succinyl-CoA: 3-oxoacid CoA-transferase causes a metabolic disease which leads to severe ketoacidosis, thus reflecting the importance of this family of enzymes. All CoA-transferases share a common mechanism in which the CoA moiety is transferred from a donor (e.g. acetyl CoA) to an acceptor, (R)-2-hydroxyglutarate, whereby acetate is formed. The transfer has been described by a ping-pong mechanism in which CoA is bound to the active-site residue of the enzyme as a covalent thiol ester intermediate. We describe here the crystal structure of glutaconate CoA-transferase (GCT) from the strictly anaerobic bacterium Acidaminococcus fermentans. This enzyme activates (R)-2-hydroxyglutarate to (R)-2-hydroxyglutaryl-CoA in the pathway of glutamate fermentation. We initiated this project to gain further insight into the function of this enzyme and the structural basis for the characteristics of CoA-transferases.Results: The crystal structure of GCT was solved by multiple isomorphous replacement to 2.55 Å resolution. The enzyme is a heterooctamer and its overall arrangement of subunits can be regarded as an (AB)4tetramer obeying 222 symmetry. Both subunits A and B belong to the open α/β-protein class and can be described as a four-layered α/α/β/α type with a novel composition and connectivity of the secondary structure elements. The core of subunit A consists of seven α/β repeats resulting in an all parallel central β sheet, against which helices pack from both sides. In contrast, the centre of subunit B is formed by a ninefold mixed β sheet. Inboth subunits the helical C terminus is folded back onto the N-terminal domain to form the third layer of helices.Conclusions: The active site of GCT is located at the interface of subunits A and B and is formed by loops of both subunits. The funnel-shaped opening to the active site has a depth and diameter of about 20 Å with the catalytic residue, Glu54 of subunit B, at the bottom. The active-site glutamate residue is stabilized by hydrogen bonds. Despite very low amino acid sequence similarity, subunits A and B reveal a similar overall fold. Large parts of their structures can be spatially superimposed, suggesting that both subunits have evolved from a common ancestor

    Estimates of Toxoplasmosis Incidence Based on Healthcare Claims Data, Germany, 2011–2016

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    Toxoplasmosis is a zoonotic infection contracted through Toxoplasma gondii–contaminated food, soil, or water. Seroprevalence in Germany is high, but estimates of disease incidence are scarce. We investigated incidences for various toxoplasmosis manifestations using anonymized healthcare claims data from Germany for 2011–2016. Patients with a toxoplasmosis diagnosis during the annual observational period were considered incident. The estimated incidence was adjusted to the general population age/sex distribution. We estimated an annual average of 8,047 toxoplasmosis patients in Germany. The average incidence of non–pregnancy-associated toxoplasmosis patients was 9.6/100,000 population. The incidence was highest in 2011, at 10.6 (95% CI 9.4–12.6)/100,000 population, and lowest in 2016, at 8.0 (95% CI 7.0–9.4)/100,000 population. The average incidence of toxoplasmosis during pregnancy was 40.3/100,000 pregnancies. We demonstrate a substantial toxoplasmosis disease burden in Germany. Public health and food safety authorities should implement toxoplasmosis-specific prevention programs.Peer Reviewe

    Analog Content-Addressable Memory from Complementary FeFETs

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    To address the increasing computational demands of artificial intelligence (AI) and big data, compute-in-memory (CIM) integrates memory and processing units into the same physical location, reducing the time and energy overhead of the system. Despite advancements in non-volatile memory (NVM) for matrix multiplication, other critical data-intensive operations, like parallel search, have been overlooked. Current parallel search architectures, namely content-addressable memory (CAM), often use binary, which restricts density and functionality. We present an analog CAM (ACAM) cell, built on two complementary ferroelectric field-effect transistors (FeFETs), that performs parallel search in the analog domain with over 40 distinct match windows. We then deploy it to calculate similarity between vectors, a building block in the following two machine learning problems. ACAM outperforms ternary CAM (TCAM) when applied to similarity search for few-shot learning on the Omniglot dataset, yielding projected simulation results with improved inference accuracy by 5%, 3x denser memory architecture, and more than 100x faster speed compared to central processing unit (CPU) and graphics processing unit (GPU) per similarity search on scaled CMOS nodes. We also demonstrate 1-step inference on a kernel regression model by combining non-linear kernel computation and matrix multiplication in ACAM, with simulation estimates indicating 1,000x faster inference than CPU and GPU

    THE POTENTIAL EFFECT OF MINI-TRAMPOLINE STIFFNESS ON TAKE-OFF BEHAVIOUR OF GYMNASTS – A METHODOLOGICAL STUDY

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    The purpose of this study was to compare two mini-trampolines with different spring constant in regard to their effect on take-off mechanics. It was expected that the softer (36 springs) trampoline would lead to a longer contact time and a higher take-off impulse. To assess reaction forces during jumps a flexible force insole was used simultaneously with the measurement of run-in velocity by timing gates. Results showed no significant differences in contact mechanics or contact time indicating that the difference between these two trampolines is only marginal. Therefore, this study provides mainly a novel measurement approach to assess the effect of equipment changes in trampolining. Future studies are warranted to assess the athlete-equipment interaction in greater detail

    The Subarcsecond Mid-Infrared View of Local Active Galactic Nuclei. IV. The L- and M-band Imaging Atlas

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    We present the largest currently existing subarcsecond 3-5 μ\mum atlas of 119 local (z<0.3z < 0.3) active galactic nuclei (AGN). This atlas includes AGN of 5 subtypes: 22 are Seyfert 1; 5 are intermediate Seyferts; 46 are Seyfert 2; 26 are LINERs; and 20 are composites/starbursts. Each AGN was observed with VLT ISAAC in the LL- and/or MM-bands between 2000 and 2013. We detect at 3σ\sigma confidence 92 sources in the LL-band and 83 sources in the MM-band. We separate the flux into unresolved nuclear flux and resolved flux through two-Gaussian fitting. We report the nuclear flux, extended flux, apparent size, and position angle of each source, giving 3σ3\sigma upper-limits for sources which are undetected. Using WISE W1- and W2-band photometry we derive relations predicting the nuclear LL and MM fluxes for Sy1 and Sy2 AGN based on their W1-W2 color and WISE fluxes. Lastly, we compare the measured mid-infrared colors to those predicted by dusty torus models SKIRTOR, CLUMPY, CAT3D, and CAT3D-WIND, finding best agreement with the latter. We find that models including polar winds best reproduce the 3-5μ\mum colors, indicating that winds are an important component of dusty torus models. We find that several AGN are bluer than models predict. We discuss several explanations for this and find that it is most plausibly stellar light contamination within the ISAAC LL-band nuclear fluxes.Comment: Main Text: 22 pages, 9 figures, 3 tables. Accepted by Ap

    Why Chromatic Imaging Matters

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    During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u-v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.Comment: Accepted for publication in Experimental Astronomy as part of the topical collection: Future of Optical-infrared Interferometry in Europ
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