Thermal noise limit in the Virgo mirror suspension

Abstract The expected current limit to the Virgo sensitivity is presented. New materials to realize a low thermal noise suspension for the Virgo optics are investigated. A promising fused silica suspension for the Virgo mirrors is presented

How will climate change affect the feeding biology of Collembola?

Collembolans are one of the most diverse and abundant group of soil invertebrates. Recent studies have shown anthropogenic climate warming to alter Collembola diversity and density in warm-dry (more detrimental effects) and warm-wet (lesser detrimental effects) conditions. Besides the direct influence of abiotic stressors, shifts in food availability could help understand variable collembolan responses to climate warming. Collembolan diet is generally formed by two main groups of soil fungi: saprotrophic and mycorrhizal fungi, which occupy different spatial niches in the soil, and are simultaneously affected by climate warming and drought. These fungal responses to climate change alter food availability for Collembola, inducing shifts in their dietary composition. Collembolans preferentially consume saprotrophic fungi, regardless of their spatial niche. However, those inhabiting deeper soil layers occasionally feed on mycorrhizal fungi and rely more frequently on such diets when other food sources become scarce. We suggest that climate change-driven scarcity of saprotrophic fungal diets in soils would make collembolans depend more on mycorrhizal fungal diets. We then discuss how such dietary shifts are driven by distinct mechanisms in warm-dry and warm-wet soil conditions. We finally call for the use of emerging techniques (e.g., stable isotope analysis, molecular gut content) to quantify the diets of Collembola more accurately under different climate change scenarios, which will help us shed more insights on how warming and precipitation variability are going to alter Collembola-fungal trophic interactions in a changing world

Large-scale automated identification of mouse brain cells in confocal light sheet microscopy images

Motivation: Recently, confocal light sheet microscopy has enabled high-throughput acquisition of whole mouse brain 3D images at the micron scale resolution. This poses the unprecedented challenge of creating accurate digital maps of the whole set of cells in a brain. Results: We introduce a fast and scalable algorithm for fully automated cell identification. We obtained the whole digital map of Purkinje cells in mouse cerebellum consisting of a set of 3D cell center coordinates. The method is accurate and we estimated an F(1) measure of 0.96 using 56 representative volumes, totaling 1.09 GVoxel and containing 4138 manually annotated soma centers. Availability and implementation: Source code and its documentation are available at http://bcfind.dinfo.unifi.it/. The whole pipeline of methods is implemented in Python and makes use of Pylearn2 and modified parts of Scikit-learn. Brain images are available on request. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online

AC Electric Fields Drive Steady Flows in Flames

We show that time-oscillating electric fields applied to plasmas present in flames create steady flows of gas. Ions generated within the flame move in the field and migrate a distance δ before recombining; the net flow of ions away from the flame creates a time-averaged force that drives the steady flows observed experimentally. A quantitative model describes the response of the flame and reveals how δ decreases as the frequency of the applied field increases. Interestingly, above a critical frequency, ac fields can be used to manipulate flames at a distance without the need for proximal electrodes.Chemistry and Chemical BiologyEngineering and Applied Science

High-fidelity imaging in brain-wide structural studies using light-sheet microscopy

Light-sheet microscopy (LSM) has proven a useful tool in neuroscience to image whole brains with high frame rates at cellular resolution and, in combination with tissue clearing methods, is often employed to reconstruct the cyto-architecture over the intact mouse brain. Inherently to LSM, however, residual opaque objects, always present to some extent even in extremely well optically cleared samples, cause stripe artifacts, which, in the best case, severely affect image homogeneity and, in the worst case, completely obscure features of interest. Here, demonstrating two example applications in intact optically cleared mouse brains, we report how Bessel beams reduce streaking artifacts and produce high-fidelity structural data for the brain-wide morphology of neuronal and vascular networks. We found that a third of the imaged volume of the brain was affected by strong striated image intensity inhomogeneity and, furthermore, a significant amount of information content lost with Gaussian illumination was accessible when interrogated with Bessel beams. In conclusion, Bessel beams produce high-fidelity structural data of improved image homogeneity and might significantly relax demands placed on the automated tools to count, trace, or segment fluorescent features of interest

E-Defense 2015 ten-story building: beam–column joint assessment according to different code-based design

Recent devastating earthquakes worldwide pointed out the importance of seismic detailing and their influence on the observed damage and subsequent repairability of reinforced concrete buildings. Several studies and post-earthquake observations remarked the role of beam–column joints (BCJs) on the global building response and the effectiveness of transverse reinforcement in increasing the joint shear strength and the ultimate deformation. Although number of experimental and theoretical studies focused on the seismic response of BCJs, their mechanical behaviour is still a discussed topic. This resulted in number of design approaches available in worldwide code or standards that lead to different quantity of joint stirrups. This study focuses on the response of BCJs of a 10-story prototype building designed according to Japanese standards and tested in 2015 on the E-Defense shaking table. First the damage assessment at global (building) and local (joint) level is performed at increasing intensities and considering the building in the base slip and base fixed configurations. A refined numerical model is then developed and validated against global and local experimental results. Then, the joint stirrups are re-designed according to different international standards (ACI, EC8, NZS) and different numerical models are developed. The numerical results are then compared in terms of interstorey drift demand and joint shear strain. Finally, a comparison in terms of expected damage varying the design approach of joint stirrups is proposed

Nanofabrication by self-assembly

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