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"Thomas, Daniel"
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A mega-phylogeny of the Annonaceae: taxonomic placement of five enigmatic genera and support for a new tribe, Phoenicantheae
The Annonaceae, the largest family in the early-divergent order Magnoliales, comprises 107 genera and c. 2,400 species. Previous molecular phylogenetic studies targeting different taxa have generated large quantities of partially overlapping DNA sequence data for many species, although a large-scale phylogeny based on the maximum number of representatives has never been reconstructed. We use a supermatrix of eight chloroplast markers (
rbcL
,
matK
,
ndhF
,
psbA-trnH
,
trnL-F
,
atpB-rbcL
,
trnS-G
and
ycf1
) to reconstruct the most comprehensive tree to date, including 705 species (29%) from 105 genera (98%). This provides novel insights into the relationships of five enigmatic genera (
Bocagea
,
Boutiquea
,
Cardiopetalum
,
Duckeanthus
and
Phoenicanthus
). Fifteen main clades are retrieved in subfamilies Annonoideae and Malmeoideae collectively, 14 of which correspond with currently recognised tribes.
Phoenicanthus
cannot be accommodated in any existing tribe, however: it is retrieved as sister to a clade comprising the tribes Dendrokingstonieae, Monocarpieae and Miliuseae, and we therefore validate a new tribe, Phoenicantheae. Our results provide strong support for many previously recognised groups, but also indicate non-monophyly of several genera (
Desmopsis
,
Friesodielsia
,
Klarobelia
,
Oxandra
,
Piptostigma
and
Stenanona
). The relationships of these non-monophyletic genera—and two other genera (
Froesiodendron
and
Melodorum
) not yet sampled—are discussed, with recommendations for future research.
Journal Article
Wind dispersal of battery-free wireless devices
Plants cover a large fraction of the Earth’s land mass despite most species having limited to no mobility. To transport their propagules, many plants have evolved mechanisms to disperse their seeds using the wind
1
–
4
. A dandelion seed, for example, has a bristly filament structure that decreases its terminal velocity and helps orient the seed as it wafts to the ground
5
. Inspired by this, we demonstrate wind dispersal of battery-free wireless sensing devices. Our millimetre-scale devices weigh 30 milligrams and are designed on a flexible substrate using programmable, off-the-shelf parts to enable scalability and flexibility for various sensing and computing applications. The system is powered using lightweight solar cells and an energy harvesting circuit that is robust to low and variable light conditions, and has a backscatter communication link that enables data transmission. To achieve the wide-area dispersal and upright landing that is necessary for solar power harvesting, we developed dandelion-inspired, thin-film porous structures that achieve a terminal velocity of 0.87 ± 0.02 metres per second and aerodynamic stability with a probability of upright landing of over 95%. Our results in outdoor environments demonstrate that these devices can travel 50–100 metres in gentle to moderate breeze. Finally, in natural systems, variance in individual seed morphology causes some seeds to fall closer and others to travel farther. We adopt a similar approach and show how we can modulate the porosity and diameter of the structures to achieve dispersal variation across devices.
A dandelion-inspired wireless solar-powered sensing device weighing 30 milligrams that transmits data through radio backscatter achieves dispersal over a wide area by travelling on the breeze, and successfully lands upright.
Journal Article
Zombie army : the Canadian Army and conscription in the Second World War
Zombie Army tells the story of Canada's Second World War military conscripts - reluctant soldiers pejoratively referred to as \"zombies\" for their perceived similarity to the mindless movie monsters of teh 1930s. In the first full-length book on the subject in almost forty years, Byers combines underused and newly discovered records to argue that although conscripts were only liable for home defence, they soon became a steady source of recruits from which the army found volunteers to serve overseas. He also challenges the traditional nationalist-dominated impression that Quebec participated only grudgingly in the war.
Book
Mid-infrared III–V semiconductor lasers epitaxially grown on Si substrates
There is currently much activity toward the integration of mid-infrared semiconductor lasers on Si substrates for developing a variety of smart, compact, sensors based on Si-photonics integrated circuits. We review this rapidly-evolving research field, focusing on the epitaxial integration of antimonide lasers, the only technology covering the whole mid-to-far-infrared spectral range. We explain how a dedicated molecular-beam epitaxy strategy allows for achieving high-performance GaSb-based diode lasers, InAs/AlSb quantum cascade lasers, and InAs/GaInSb interband cascade lasers by direct growth on on-axis (001)Si substrates, whereas GaAs-on-Si or GaSb-on-Si layers grown by metal-organic vapor phase epitaxy in large capability epitaxy tools are suitable templates for antimonide laser overgrowth. We also show that etching the facets of antimonide lasers grown on Si is a viable approach in view of photonic integrated circuits. Remarkably, this review shows that while diode lasers are sensitive to residual crystal defects, the quantum cascade and interband cascade lasers grown on Si exhibit performances comparable to those of similar devices grown on their native substrates, due to their particular band structures and radiative recombination channels. Long device lifetimes have been extrapolated for interband cascade lasers. Finally, routes to be further explored are also presented.
Journal Article
Resisting AI : an anti-fascist approach to artificial intelligence
\"Artificial Intelligence (AI) is everywhere, yet it causes damage to society in ways that can't be fixed. Calling for the restructuring of AI, Dan McQuillan sets out an anti-fascist approach that replaces exclusions with caring and outlines new mechanisms that support collective freedom. Artificial Intelligence (AI) is everywhere, yet it causes damage to society in ways that can't be fixed. Instead of helping to address our current crises, AI causes divisions that limit people's life chances, and even suggests fascistic solutions to social problems. This book provides an analysis of AI's deep learning technology and its political effects and traces the ways that it resonates with contemporary political and social currents, from global austerity to the rise of the far right. Dan McQuillan calls for us to resist AI as we know it and restructure it by prioritising the common good over algorithmic optimisation. He sets out an anti-fascist approach to AI that replaces exclusions with caring, proposes people's councils as a way to restructure AI through mutual aid and outlines new mechanisms that would adapt to changing times by supporting collective freedom. Academically rigorous, yet accessible to a socially engaged readership, this unique book will be of interest to all who wish to challenge the social logic of AI by reasserting the importance of the common good\"--Back cover.
Book
Neural evidence supports a dual sensory-motor role for insect wings
Flying insects use feedback from various sensory modalities including vision and mechanosensation to navigate through their environment. The rapid speed of mechanosensory information acquisition and processing compensates for the slower processing times associated with vision, particularly under low light conditions. While halteres in dipteran species are well known to provide such information for flight control, less is understood about the mechanosensory roles of their evolutionary antecedent, wings. The features that wing mechanosensory neurons (campaniform sensilla) encode remains relatively unexplored. We hypothesized that the wing campaniform sensilla of the hawkmoth, Manduca sexta, rapidly and selectively extract mechanical stimulus features in a manner similar to halteres. We used electrophysiological and computational techniques to characterize the encoding properties of wing campaniform sensilla. To accomplish this, we developed a novel technique for localizing receptive fields using a focused IR laser that elicits changes in the neural activity of mechanoreceptors. We found that (i) most wing mechanosensors encoded mechanical stimulus features rapidly and precisely, (ii) they are selective for specific stimulus features, and (iii) there is diversity in the encoding properties of wing campaniform sensilla. We found that the encoding properties of wing campaniform sensilla are similar to those for haltere neurons. Therefore, it appears that the neural architecture that underlies the haltere sensory function is present in wings, which lends credence to the notion that wings themselves may serve a similar sensory function. Thus, wings may not only function as the primary actuator of the organism but also as sensors of the inertial dynamics of the animal.
Journal Article
Advanced 3D additive manufacturing techniques for revolutionizing the next-generation rocket engine nozzle fabrication
The aim of this study was to evaluate the redesign and additive manufacturing of a rocket engine nozzle using Inconel 625 material. The redesigned engine took into consideration material shrinkage during the metal transfer process. The additive manufacturing process was carried out using the appropriate toolpaths to form a solid structure. Micrographs of the additively manufactured structure showed layer resolution and fine detail, as well as the presence of metallic particles within the polymer matrix. The final rocket engine nozzle produced was found to have the necessary mechanical and metallurgical properties required for practical use in future space vehicle operations. This was demonstrated by tensile tests carried out at various temperatures and 3D white light interferometry scans of the surface properties. The results of the study suggest that additive manufacturing and Inconel 625 material can be used to produce high-performance rocket engine nozzles that meet the requirements of the aerospace industry. This study provides valuable insights into the potential applications of additive manufacturing in the aerospace industry and may lead to the development of new, high-performance rocket engine nozzles.
Journal Article