Although bamboo has been used structurally for millennia, there is currently increasing interest in the development of renewable and sustainable structural bamboo products (SBPs). These SBPs are ...analogous to wood products such as plywood, oriented strand board and glue-laminated wood. In this study, the properties of natural Moso bamboo (Phyllostachys pubescens) are investigated to further enable the processing and design of SBPs. The radial and longitudinal density gradients in bamboo give rise to variations in the mechanical properties. Here, we measure the flexural properties of Moso bamboo in the axial direction, along with the compressive strengths in the axial and transverse directions. Based on the microstructural variations (observed with scanning electron microscopy) and extrapolated solid cell wall properties of bamboo, we develop models, which describe the experimental results well. Compared to common North American construction woods loaded along the axial direction, Moso bamboo is approximately as stiff and substantially stronger, in both flexure and compression but denser. This work contributes to critical knowledge surrounding the microstructure and mechanical properties of bamboo, which are vital to the engineering and design of sustainable SBPs.
AIM: National and international policy frameworks, such as the European Union's Renewable Energy Directive, increasingly seek to conserve and reference ‘highly biodiverse grasslands’. However, to ...date there is no systematic global characterization and distribution map for grassland types. To address this gap, we first propose a systematic definition of grassland. We then integrate International Vegetation Classification (IVC) grassland types with the map of Terrestrial Ecoregions of the World (TEOW). LOCATION: Global. METHODS: We developed a broad definition of grassland as a distinct biotic and ecological unit, noting its similarity to savanna and distinguishing it from woodland and wetland. A grassland is defined as a non‐wetland type with at least 10% vegetation cover, dominated or co‐dominated by graminoid and forb growth forms, and where the trees form a single‐layer canopy with either less than 10% cover and 5 m height (temperate) or less than 40% cover and 8 m height (tropical). We used the IVC division level to classify grasslands into major regional types. We developed an ecologically meaningful spatial catalogue of IVC grassland types by listing IVC grassland formations and divisions where grassland currently occupies, or historically occupied, at least 10% of an ecoregion in the TEOW framework. RESULTS: We created a global biogeographical characterization of the Earth's grassland types, describing approximately 75% of IVC grassland divisions with ecoregions. We mapped 49 IVC grassland divisions. Sixteen additional IVC grassland divisions are absent from the map because of the fine‐scale distribution of these grassland types. MAIN CONCLUSIONS: The framework provided by our geographical mapping effort provides a systematic overview of grasslands and sets the stage for more detailed classification and mapping at finer scales. Each regional grassland type can be characterized in terms of its range of biodiversity, thereby assisting in future policy initiatives.
Delocalized photonic deep learning on the internet’s edge Sludds, Alexander; Bandyopadhyay, Saumil; Chen, Zaijun ...
Science (American Association for the Advancement of Science),
10/2022, Letnik:
378, Številka:
6617
Journal Article
Recenzirano
Odprti dostop
Advanced machine learning models are currently impossible to run on edge devices such as smart sensors and unmanned aerial vehicles owing to constraints on power, processing, and memory. We introduce ...an approach to machine learning inference based on delocalized analog processing across networks. In this approach, named Netcast, cloud-based “smart transceivers” stream weight data to edge devices, enabling ultraefficient photonic inference. We demonstrate image recognition at ultralow optical energy of 40 attojoules per multiply (<1 photon per multiply) at 98.8% (93%) classification accuracy. We reproduce this performance in a Boston-area field trial over 86 kilometers of deployed optical fiber, wavelength multiplexed over 3 terahertz of optical bandwidth. Netcast allows milliwatt-class edge devices with minimal memory and processing to compute at teraFLOPS rates reserved for high-power (>100 watts) cloud computers.
Learning on the edge
Smart devices such as cell phones and sensors are low-power electronics operating on the edge of the internet. Although they are increasingly more powerful, they cannot perform complex machine learning tasks locally. Instead, such devices offload these tasks to the cloud, where they are performed by factory-sized servers in data centers, creating issues related to large power consumption, latency, and data privacy. Sludds
et al
. introduce an edge-computing architecture called NetCast that makes use of the strengths of photonics and electronics. In this method, smart transceivers periodically broadcast the weights of commonly used deep neural networks. The architecture allows low-power edge devices with minimal memory and processing to compute at teraflop rates otherwise reserved for high-power cloud computers. —ISO
A new computing architecture allows low-power edge devices to perform at levels otherwise reserved for data centers.
Si-based Li-ion battery anodes have recently received great attention, as they offer specific capacity an order of magnitude beyond that of conventional graphite. The applications of this ...transformative technology require synthesis routes capable of producing safe and easy-to-handle anode particles with low volume changes and stable performance during battery operation. Herein, we report a large-scale hierarchical bottom-up assembly route for the formation of Si on the nanoscale--containing rigid and robust spheres with irregular channels for rapid access of Li ions into the particle bulk. Large Si volume changes on Li insertion and extraction are accommodated by the particle's internal porosity. Reversible capacities over five times higher than that of the state-of-the-art anodes (1,950 mA h g(-1)) and stable performance are attained. The synthesis process is simple, low-cost, safe and broadly applicable, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power.
Abstract
In this paper, an objective analysis of spatial tornado risk in the United States is performed, using a somewhat different dataset than in some previous tornado climatologies. The focus is ...on significant tornadoes because their reporting frequency has remained fairly stable for several decades. Also, data before 1973 are excluded, since those tornadoes were rated after the fact and were often overrated. Tornado pathlength within the vicinity of a grid point is used to show tornado risk, as opposed to tornado days or the total number of reported tornadoes. The possibility that many tornadoes in the Great Plains were underrated due to the lack of damage indicators, causing a low bias in the number of significant tornadoes there, is mostly discounted through several analyses. The kernel density analysis of 1973–2011 significant tornadoes performed herein shows that the area of highest risk for tornadoes in the United States extends roughly from Oklahoma to Tennessee and northwestern Georgia, with the highest risk in the southeastern United States, from central Arkansas across most of Mississippi and northern Alabama.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A review of the potential diverse catalytic and binding roles of plant glutathione transferases in secondary metabolism and the techniques for identifying these functions.
Plant glutathione ...transferases (GSTs) are classified as enzymes of secondary metabolism, but while their roles in catalysing the conjugation and detoxification of herbicides are well known, their endogenous functions are largely obscure. Thus, while the presence of GST-derived
S-glutathionylated xenobiotics have been described in many plants, there is little direct evidence for the accumulation of similarly conjugated natural products, despite the presence of a complex and dichotomous metabolic pathway which processes these reaction products. The conservation in glutathione conjugating and processing pathways, the co-regulation of GSTs with inducible plant secondary metabolism and biochemical studies showing the potential of these enzymes to conjugate reactive natural products are all suggestive of important endogenous functions. As a framework for addressing these enigmatic functions we postulate that either: (a) the natural reaction products of GSTs are unstable and undergo reversible
S-glutathionylation; (b) the conjugation products of GSTs are very rapidly processed to derived metabolites; (c) GSTs do not catalyse conventional conjugation reactions but instead use glutathione as a cofactor rather than co-substrate; or (d) GSTs are non-catalytic and function as transporter proteins for secondary metabolites and their unstable intermediates. In this review, we describe how enzyme biochemistry and informatics are providing clues as to GST function allowing for the critical evaluation of each of these hypotheses. We also present evidence for the involvement of GSTs in the synthesis of sulfur-containing secondary metabolites such as volatiles and glucosinolates, and the conjugation, transport and storage of reactive oxylipins, phenolics and flavonoids.
We demonstrate Gaussian-shaped phase matching of a periodically-poled potassium titanyl phosphate (PPKTP) crystal by imposing a custom duty-cycle pattern on its grating structure while keeping the ...grating period fixed. The PPKTP's phase-matching characteristics are verified through optical difference-frequency generation measurements, showing good agreement with expected values based on our design parameters. Our theoretical analysis predicts that under extended phase-matching conditions the custom-poled PPKTP crystal is capable of generating heralded single photons with a spectral purity of 97%, and can reach as high as 99.5% with gentle spectral filtering, something that is highly desirable for photonic quantum information processing applications.
There has been much research on the associations between weather variables and suicide rates. However, the state of understanding has remained rather stagnant due to many contradictory findings. The ...purpose of this project is to examine a larger database of suicides that includes a longer and more recent period of record (1975–2010) across numerous locations in the USA. In all, we examine nine total counties (and the primary city associated with them) with a special effort made to compare locations with varying degrees of temperature seasonality: Cook (Chicago), Fulton (Atlanta), King (Seattle), Los Angeles (Los Angeles), Maricopa (Phoenix), Miami-Dade (Miami), Philadelphia (Philadelphia), Salt Lake (Salt Lake City), and St. Louis (St. Louis). We first examine the unique seasonal cycle in suicides evident in each locale and then use distributed lag nonlinear modeling (DLNM) to relate the suicide data to daily surface temperatures. Results suggest that a late spring/summer peak generally exists in suicide rates, and above average temperatures are associated with increased suicide risk in almost all study counties. Further, it appears that these associations can be found in both mid-latitude and sub-tropical climate types.
We report on the use of an interferometric weak value technique to amplify very small transverse deflections of an optical beam. By entangling the beam's transverse degrees of freedom with the ...which-path states of a Sagnac interferometer, it is possible to realize an optical amplifier for polarization independent deflections. The theory for the interferometric weak value amplification method is presented along with the experimental results, which are in good agreement. Of particular interest, we measured the angular deflection of a mirror down to 400+/-200 frad and the linear travel of a piezo actuator down to 14+/-7 fm.
What is the impact of garden-based learning on academic outcomes in schools? To address this question, findings across 152 articles (1990–2010) were analyzed resulting in 48 studies that met the ...inclusion criteria for this synthesis. A review template with operational coding framework was developed. The synthesis results showed a preponderance of positive impacts on direct academic outcomes with the highest positive impact for science followed by math and language arts. Indirect academic outcomes were also measured with social development surfacing most frequently and positively. These results were consistent across programs, student samples, and school types and within the disparate research methodologies used. However, a common issue was lack of research rigor as there were troubling issues with incomplete descriptions of methodological procedures in general and sampling techniques and validity in particular. Recommendations for more systematic and rigorous research are provided to parallel the growing garden-based education movement.
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