Force modulation: A behavioural marker of mind-wandering.

It is known that the Metronome Response Task (MRT)-one of the most used mind-wandering sampling paradigms, struggles to differentiate between spontaneous mind-wandering (wherein one's attention is uncontrollably shifted away from the task at hand) and deliberate mind-wandering (wherein one's attention is purposefully shifted away). Thus, we endeavoured to design and test a new mind-wandering measure, called the In Sync Task (IST), that can achieve such differentiation more readily. Unlike the MRT, which involves having participants click in sync (using a mouse) with rhythmically presented, auditory monotones, the IST requires participants to (1) click in sync with tone triplets that increase incrementally in loudness and (2) modulate their clicking force to the presented tone's loudness. Here, we measured (1) participants' variabilities in their rhythmic response times (as is the MRT) and (2) their consistency in appropriately modulating their clicking force. Across two separate samples of university students (n = 119 and n = 121) collected between June 2022 to February 2023, we showed performance differences between the mind-wandering subtypes. Specifically, participants were better able to modulate their clicking force during epochs of spontaneous, compared with deliberate, mind-wandering, whereas the MRT was unable to differentiate between these conditions. In sum, we show that there appear to be greater costs to performance when one deliberately mind-wanders, as opposed to spontaneously mind-wandering.

Densification effect on field emission characteristics of CNT film emitters for electron emission devices.

Field electron emission characteristics of the carbon nanotube (CNT) film emitters were investigated according to densification conditions such as nitric acid, acetic acid, and salicylic acid. The emission performance of the CNT film emitters was strongly affected by the densification conditions. Salicylic acid exhibits the best field electron emission properties of the CNT film emitters, followed by nitric acid and acetic acid. The efficient densification of the CNT film emitter by salicylic acid is caused by the role of polarity and p orbitals, nitric acid by hydrogen ions, and acetic acid by weak polarity. After the densification with salicylic acid, the turn-on field of the CNT film emitter decreases from 1.94 Vµm-1to 1.86 Vµm-1, the threshold field decreases from 3.41 Vµm-1to 2.95 Vµm-1, the emission current significantly increases from 20.92 mA to 43.98 mA, and the degradation rate from the long-term emission stability decreases from 49.9% to 21%. The improved emission characteristics are attributed to the increased emission sites at the CNT film and the increased electrical conductivity of the CNT film. The densification is a useful way to enhance the field electron emission properties of CNT film emitters.

High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter.

A cold cathode X-ray tube was fabricated using a carbon nanotube (CNT) field electron emitter made by a free-standing CNT film which is composed of a highly packed CNT network. A lot of CNT bundles with a sharp tip are vertically aligned at the edge of the thin CNT film with a length of 10 mm and a thickness of 7 µm. The cold cathode X-ray tube using the CNT field emitter presents an extremely high tube current density of 152 A/cm2 (corresponding to tube current of 106.4 mA), the electron beam transmittance of 95.2% and a small focal spot size (FSS) of 0.5 mm. In addition, the cold cathode X-ray tube also shows stable lifetime during 100 000 shots. High emission current density of the cold cathode X-ray tube is mainly attributed to a lot of electron emission sites at an edge of the CNT film. The small FSS is caused by an ensemble of the CNT field electron emitter made by a free-standing thin CNT film and the optimized curve-shape elliptical focusing lens. Based on obtained results, the cold cathode X-ray tube can be widely used for various X-ray applications such as medical diagnosis systems and security check systems in the future.

Saccadic eye movement metrics reflect surprise and mental model updating.

Two experiments investigated what eye movements can reveal about how we process surprising information and how we update mental models in dynamic and unstructured environments. Participants made saccades to visual targets presented one at a time, radially, around an invisible perimeter. Target locations were normally distributed and shifted at an unannounced point during the task. Trials following the shift were considered surprising and unexpected. These unexpected and surprising events prompted the need to update. Slower saccadic latencies were observed for surprising/unexpected events, perhaps indicative of the need to reorient attention to the unexpected target location. Longer dwell times were observed for events that signaled a change in the distribution. These data show that eye movement metrics provide a reliable indicator of mental model updating when contingencies change even in the absence of explicit change signals.