Structural optimization of 3D masonry buildings

In the design of buildings, structural analysis is traditionally performed after the aesthetic design has been determined and has little influence on the overall form. In contrast, this paper presents an approach to guide the form towards a shape that is more structurally sound. Our work is centered on the study of how variations of the geometry might improve structural stability. We define a new measure of structural soundness for masonry buildings as well as cables, and derive its closed-form derivative with respect to the displacement of all the vertices describing the geometry. We start with a gradient descent tool which displaces each vertex along the gradient. We then introduce displacement operators, imposing constraints such as the preservation of orientation or thickness; or setting additional objectives such as volume minimization.Shell Oil CompanyNatural Sciences and Engineering Research Council of Canada (PGS Program)Samsung Scholarship Foundatio

Dopamine D_2-receptor activation elicits akinesia, rigidity, catalepsy, and tremor in mice expressing hypersensitive 4 nicotinic receptors via a cholinergic-dependent mechanism

Recent studies suggest that high-affinity neuronal nicotinic acetylcholine receptors (nAChRs) containing α4 and β2 subunits (α4β2*) functionally interact with G-protein-coupled dopamine (DA) D_2 receptors in basal ganglia. We hypothesized that if a functional interaction between these receptors exists, then mice expressing an M2 point mutation (Leu9'Ala) rendering 4 nAChRs hypersensitive to ACh may exhibit altered sensitivity to a D_2-receptor agonist. When challenged with the D_(2)R agonist, quinpirole (0.5–10 mg/kg), Leu9'Ala mice, but not wild-type (WT) littermates, developed severe, reversible motor impairment characterized by rigidity, catalepsy, akinesia, and tremor. While striatal DA tissue content, baseline release, and quinpirole-induced DA depletion did not differ between Leu9'Ala and WT mice, quinpirole dramatically increased activity of cholinergic striatal interneurons only in mutant animals, as measured by increased c-Fos expression in choline acetyltransferase (ChAT)-positive interneurons. Highlighting the importance of the cholinergic system in this mouse model, inhibiting the effects of ACh by blocking muscarinic receptors, or by selectively activating hypersensitive nAChRs with nicotine, rescued motor symptoms. This novel mouse model mimics the imbalance between striatal DA/ACh function associated with severe motor impairment in disorders such as Parkinson’s disease, and the data suggest that a D_(2)R–α4*-nAChR functional interaction regulates cholinergic interneuron activity.—Zhao-Shea, R., Cohen, B. N., Just, H., McClure-Begley, T., Whiteaker, P., Grady, S. R., Salminen, O., Gardner, P. D., Lester, H. A., Tapper, A. R. Dopamine D2-receptor activation elicits akinesia, rigidity, catalepsy, and tremor in mice expressing hypersensitive α4 nicotinic receptors via a cholinergic-dependent mechanism

Solar Neutron Events of October-November 2003

During the period when the Sun was intensely active on October-November 2003, two remarkable solar neutron events were observed by the ground-based neutron monitors. On October 28, 2003, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 sigma) by the neutron monitor at Tsumeb, Namibia. On November 4, 2003, in association with an X28 class flare, relativistic solar neutrons were observed by the neutron monitors at Haleakala in Hawaii and Mexico City, and by the solar neutron telescope at Mauna Kea in Hawaii simultaneously. Clear excesses were observed at the same time by these detectors, with the significance calculated as 7.5 sigma for Haleakala, and 5.2 sigma for Mexico City. The detector onboard the INTEGRAL satellite observed a high flux of hard X-rays and gamma-rays at the same time in these events. By using the time profiles of the gamma-ray lines, we can explain the time profile of the neutron monitor. It appears that neutrons were produced at the same time as the gamma-ray emission.Comment: 35 pages, 21 figures, accepted for publication in Ap

Cryogenic Design of a PrFeB Based Undulator

A PrFeB based cryogenic undulator has been built at Helmholtz Zentrum Berlin HZB in collaboration with the Ludwig Maximilian University München LMU . LMU will operate the undulator at a laser plasma accelerator at the Max Planck Institut für Quantenoptik in Garching. The 20 period device has a period length of 9mm and a fixed gap of 2.5mm. The operation of a small gap device at a high emittance electron beam requires stable magnetic material. A high coercivity is achieved with PrFeB material cooled down to 20 30K. In this paper we present the mechanic, magnetic and cryogenic design and compare predictions with measured dat

Towards the improvement of methane production in CO2 photoreduction using Bi2WO6/TiO2 heterostructures

Russelite bismuth tungstate (Bi2WO6) has been widely reported for the photocatalytic degradation and mineralization of a myriad of pollutants as well as organic compounds. These materials present perovskite-like structure with hierarchical morphologies, which confers excellent optoelectronic properties as potentials candidates for photocatalytic solar fuels production. Here, we propose the development of Bi2WO6/TiO2 heterojunctions for CO2 photoreduction, as a promising solution to produce fuels, alleviate global warming and tackle fossil fuel shortage. Our results show an improvement of the photocatalytic activity of the heterojunctions compared to the pristine semiconductors. Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) experiments reveals a preferential CO2 adsorption over TiO2. On the other hand, transient absorption spectroscopy measurements show that the charge transfer pathway in Bi2WO6/TiO2 hybrids leads to longer-lived photogenerated carriers in spatially separated redox active sites, which favor the reduction of CO2 into highly electron demanding fuels and chemicals, such as CH4 and C2H6Financial support has been received from the European Research Council (ERC), through HYMAP project (grant agreement No. 648319), under the European Union's Horizon 2020 research and innovation program, as well as from the Marie Sklodowska-Curie grant agreement No. 754382. L.C. acknowledges funding from the project ARMONIA (PID2020–119125RJ-I00) funded by MCIN/AEI/10.13039/ 501100011033. Financial support has also been received from AEIMINECO/FEDER (Nympha Project, PID2019–106315RB-I00), "Comunidad de Madrid" regional government, and the European Structural Funds (FotoArt-CM project, S2018/NMT-4367). Authors also acknowledge financial support from the grant PLEC2021–007906 funded by MCIN/AEI/10.13039/501100011033 and the "European Union NextGenerationEU/PRTR"

Corrigendum to “Effects of therapeutic hypothermia on the gut microbiota and metabolome of infants suffering hypoxic-ischemic encephalopathy at birth” [Int. J. Biochem. Cell Biol. 93 (December) (2017), 110-118]

peer-reviewedCorrigendum Refers to: Watkins, C., Murphy, K., Yen, S., Carafa, I., Dempsey, E., O’Shea, C., Vercoe, E., Ross, R., Stanton, C. and Ryan, C. (2017). Effects of therapeutic hypothermia on the gut microbiota and metabolome of infants suffering hypoxic-ischemic encephalopathy at birth. The International Journal of Biochemistry & Cell Biology, [online] 93, pp.110-118. Available at: https://doi.org/10.1016/j.biocel.2017.08.01

Superconductivity in Ropes of Single-Walled Carbon Nanotubes

We report measurements on ropes of Single Walled Carbon Nanotubes (SWNT) in low-resistance contact to non-superconducting (normal) metallic pads, at low voltage and at temperatures down to 70 mK. In one sample, we find a two order of magnitude resistance drop below 0.55 K, which is destroyed by a magnetic field of the order of 1T, or by a d.c. current greater than 2.5 microA. These features strongly suggest the existence of superconductivity in ropes of SWNT.Comment: Accepted for publication in Phys. Rev. Let

Deep neural networks allow expert-level brain meningioma segmentation and present potential for improvement of clinical practice

Accurate brain meningioma segmentation and volumetric assessment are critical for serial patient follow-up, surgical planning and monitoring response to treatment. Current gold standard of manual labeling is a time-consuming process, subject to inter-user variability. Fully-automated algorithms for meningioma segmentation have the potential to bring volumetric analysis into clinical and research workflows by increasing accuracy and efficiency, reducing inter-user variability and saving time. Previous research has focused solely on segmentation tasks without assessment of impact and usability of deep learning solutions in clinical practice. Herein, we demonstrate a three-dimensional convolutional neural network (3D-CNN) that performs expert-level, automated meningioma segmentation and volume estimation on MRI scans. A 3D-CNN was initially trained by segmenting entire brain volumes using a dataset of 10,099 healthy brain MRIs. Using transfer learning, the network was then specifically trained on meningioma segmentation using 806 expert-labeled MRIs. The final model achieved a median performance of 88.2% reaching the spectrum of current inter-expert variability (82.6-91.6%). We demonstrate in a simulated clinical scenario that a deep learning approach to meningioma segmentation is feasible, highly accurate and has the potential to improve current clinical practice

Energy Landscape and Global Optimization for a Frustrated Model Protein

The three-color (BLN) 69-residue model protein was designed to exhibit frustrated folding. We investigate the energy landscape of this protein using disconnectivity graphs and compare it to a Go model, which is designed to reduce the frustration by removing all non-native attractive interactions. Finding the global minimum on a frustrated energy landscape is a good test of global optimization techniques, and we present calculations evaluating the performance of basin-hopping and genetic algorithms for this system.Comparisons are made with the widely studied 46-residue BLN protein.We show that the energy landscape of the 69-residue BLN protein contains several deep funnels, each of which corresponds to a different β-barrel structure