Connectivity in metallic nanowire networks with resistive junctions is manipulated by applying an electric field to create materials with tunable electrical conductivity. In situ electron microscope and electrical measurements visualize the activation and evolution of connectivity within these networks. Modeling nanowire networks, having a distribution of junction breakdown voltages, reveals universal scaling behavior applicable to all network materials. We demonstrate how local connectivity within these networks can be programmed and discuss material and device applications.

The Sun is an active star that can launch large eruptions of magnetised plasma into the heliosphere, called coronal mass ejections (CMEs). These ejections can drive shocks that accelerate particles to high energies, often resulting in radio emission at low frequencies (<200 MHz). To date, the relationship between the expansion of CMEs, shocks and particle acceleration is not well understood, partly due to the lack of radio imaging at low frequencies during the onset of shock-producing CMEs. Here, we report multi-instrument radio, white-light and ultraviolet imaging of the second largest flare in Solar Cycle 24 (2008-present) and its associated fast CME (3038±288 km/s). We identify the location of a multitude of radio shock signatures, called herringbones, and find evidence for shock accelerated electron beams at multiple locations along the expanding CME. These observations support theories of non-uniform, rippled shock fronts driven by an expanding CME in the solar corona.Particles accelerated in collisionless shocks are of particular interest in space plasmas and are often associated with CMEs from the Sun. Shocks and related high-energy particles can propagate through the heliosphere, influencing planetary ionospheres and atmospheres, and also affecting technological systems at Earth (for a review see [1]). Such processes are not limited to our solar system; other stars are expected to produce even larger CMEs, stronger shocks and more powerful particle acceleration [2]. Particles accelerated by these powerful eruptions from other stars can even affect the habitability of exoplanets [3]. Since observations of stellar eruptions are very limited, studying particle acceleration at the Sun is of crucial importance for understanding these processes universally.Fast CMEs (with speeds up to ∼3,500 km/s [4,5]) are powerful drivers of plasma shocks that can accelerate particles up to relativistic speeds producing bursts of plasma emission at radio wavelengths [6]. The most obvious manifestations of shocks at radio wavelengths on the Sun are a class of radio bursts, Type II bursts, mostly observed at frequencies <150 MHz [7,8,9]. They usually show two emission lanes slowly drifting to lower frequencies in dynamic spectra, with a 2:1 frequency ratio representing emission at the fundamental and harmonic plasma frequency. Type II bursts have been imaged on multiple occasions showing sources closely associated with CMEs [8,10,11], while simulations and CME reconstructions closely associate Type IIs with CME shocks [12,13]. In some cases, 'bursty' signatures of individual electron beams accelerated by CME shocks can be identified in 2 dynamic spectra superimposed on Type II bursts [14]. These electron beam signatures, called 'herringbones', are identified as narrow bursts of radiation drifting towards higher and lower frequencies, categorised as distinct emission from the accompanying Type II burst [15,16], and sometimes even observed without a Type II [15,17]. Despite the wealth of publications on Type II bursts, there ha...

Solar flares often display pulsating and oscillatory signatures in the emission, known as quasi-periodic pulsations (QPP). QPP are typically identified during the impulsive phase of flares, yet in some cases, their presence is detected late into the decay phase. Here, we report extensive fine structure QPP that are detected throughout the large X8.2 flare from 2017 September 10. Following the analysis of the thermal pulsations observed in the GOES/XRS and the 131Å channel of SDO/AIA, we find a pulsation period of ∼65 s during the impulsive phase followed by lower amplitude QPP with a period of ∼150 s in the decay phase, up to three hours after the peak of the flare. We find that during the time of the impulsive QPP, the soft X-ray source observed with RHESSI rapidly rises at a velocity of approximately 17 kms −1 following the plasmoid/coronal mass ejection (CME) eruption. We interpret these QPP in terms of a manifestation of the reconnection dynamics in the eruptive event. During the long-duration decay phase lasting several hours, extended downward contractions of collapsing loops/plasmoids that reach the top of the flare arcade are observed in EUV. We note that the existence of persistent QPP into the decay phase of this flare are most likely related to these features. The QPP during this phase are discussed in terms of MHD wave modes triggered in the post-flaring loops.