Among all superconducting undulator geometries, a helical undulator provides a very compact geometry and further is more effective in producing synchrotron radiation, providing circularly polarized ...photons, which are widely usable for synchrotron radiation users. These characteristics make it a very attractive option for realizing more compact free-electron lasers, requiring a combination of short-period and high-field undulators to produce coherent light up to X-rays. To further increase the magnetic field at 4.2 K and achieve larger operating margins as compared with low-temperature superconductors, the application of a high-temperature superconductor (HTS) in the form of coated rare-Earth barium copper oxide tapes was investigated. This article presents the design and manufacturing work done on an HTS helical undulator prototype-the very first helical undulator design based on HTS tape winding to the best of the authors' knowledge. To provide proof of concept, a five-period short-model demonstrator was realized by a bifilar, no-insulation winding scheme from a single piece of HTS cable, wound with a period length of 13 mm and a magnetic gap of 5 mm. First powering tests at 77 K, performed in liquid nitrogen, revealed stable operations up to the calculated critical current of 140 A and even above. Higher currents of up to 160 A showed the expected coil protection, enabling the current to bypass the appearance of normal conducting zones and redistribute without degrading the superconductor.
Stomata are microscopic pores found on the surfaces of leaves that act to control CO
uptake and water loss. By integrating information derived from endogenous signals with cues from the surrounding ...environment, the guard cells, which surround the pore, 'set' the stomatal aperture to suit the prevailing conditions. Much research has concentrated on understanding the rapid intracellular changes that result in immediate changes to the stomatal aperture. In this study, we look instead at how stomata acclimate to longer timescale variations in their environment. We show that the closure-inducing signals abscisic acid (ABA), increased CO
, decreased relative air humidity and darkness each access a unique gene network made up of clusters (or modules) of common cellular processes. However, within these networks some gene clusters are shared amongst all four stimuli. All stimuli modulate the expression of members of the PYR/PYL/RCAR family of ABA receptors. However, they are modulated differentially in a stimulus-specific manner. Of the six members of the PYR/PYL/RCAR family expressed in guard cells, PYL2 is sufficient for guard cell ABA-induced responses, whereas in the responses to CO
, PYL4 and PYL5 are essential. Overall, our work shows the importance of ABA as a central regulator and integrator of long-term changes in stomatal behaviour, including sensitivity, elicited by external signals. Understanding this architecture may aid in breeding crops with improved water and nutrient efficiency.
The insulatormetal transition remains among the most studied phenomena in correlated electron physics. However, the spontaneous formation of spatial patterns amidst insulatormetal phase coexistence ...remains poorly explored on the mesoand nanoscales. Here we present real-space evolution of the insulatormetal transition in a V2O3 thin lm imaged at high spatial resolution by cryogenic near-eld infrared microscopy. We resolve spontaneously nanotextured coexistence of metal and correlated Mott insulator phases near the insulatormetal transition (160180 K) associated with percolation and an underlying structural phase transition. Augmented with macroscopic temperature-resolved X-ray diraction measurements of the same lm, a quantitative analysis of nano-infrared images acquired across the transition suggests decoupling of electronic and structural transformations. Persistent low-temperature metallicity is accompanied by unconventional critical behaviour, implicating the long-range Coulomb interaction as a driving force through the lms rst-order insulatormetal transition.
Mutualisms are of fundamental importance in all ecosystems but their very existence poses a series of challenging evolutionary questions. Recently, the application of molecular analyses combined with ...theoretical advances have transformed our understanding of many specific systems, thereby contributing to the possibility of a more general understanding of the factors that influence mutualisms.
Vanadium dioxide (VO
) is a material that undergoes an insulator-metal transition upon heating above 340 K. It remains debated as to whether this electronic transition is driven by a corresponding ...structural transition or by strong electron-electron correlations. Here, we use apertureless scattering near-field optical microscopy to compare nanoscale images of the transition in VO
thin films acquired at both mid-infrared and terahertz frequencies, using a home-built terahertz near-field microscope. We observe a much more gradual transition when THz frequencies are utilized as a probe, in contrast to the assumptions of a classical first-order phase transition. We discuss these results in light of dynamical mean-field theory calculations of the dimer Hubbard model recently applied to VO
, which account for a continuous temperature dependence of the optical response of the VO
in the insulating state.
Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner ...surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na+-rich animal and nutrition for the plant.
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•Carnivorous Dionaea muscipula captures and processes nutrient- and sodium-rich prey•Via mechano-sensor stimulation, an animal meal is recognized, captured, and processed•Mechano-electrical waves induce JA signaling pathways that trigger prey digestion•Number of stimulations controls the production of digesting enzymes and uptake modules
Children are able to count at the age of 15–18 months. In this work, Böhm et al. demonstrate that the carnivorous Venus flytrap plant is able to count as well. The leaf tips develop into snap traps, where the number of contacts of the prey with mechano-sensitive trap initiates capturing and processing of the animal victim.
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