Upset and Unfocused: ADHD symptoms and cognitive abilities as moderators for working memory performance under varying levels of emotional load

Background: ADHD symptoms are prevalent among college students and frequently cause executive function (EF) impairments. While EF impairments are well studied in this population, the interaction between emotional arousal/mood, working memory (WM), ADHD symptoms and cognitive abilities (CA) still remains unclear. Methods: 50 undergraduate participants’ ADHD symptoms and EF were assessed through cognitive assessments and behavioral questionnaires before they completed WM tasks under varying levels of laboratory-induced emotional load. Results: Participants with high ADHD symptoms and/or low CA struggled with the experimental WM task. Under emotional load, those with hyperactive-impulsive ADHD symptoms struggled with self-regulatory aspects of EF: producing more intrusions and recognition errors. The CA groups’ deficits were tied closer to recall ability – with and without added load. Conclusion: These findings further support that there are many reasons for WM challenges and that there is no single assessment that can identify the underlying cause of these struggles.Individual Studies Program, University of Marylan

Nanomechanical testing of silica nanospheres for levitated optomechanics experiments

Optically-levitated dielectric particles can serve as ultra-sensitive detectors of feeble forces and torques, as tools for use in quantum information science, and as a testbed for quantum coherence in macroscopic systems. Knowledge of the structural and optical properties of the particles is important for calibrating the sensitivity of such experiments. Here we report the results of nanomechanical testing of silica nanospheres and investigate an annealing approach which can produce closer to bulk-like behavior in the samples in terms of their elastic moduli. These results, combined with our experimental investigations of optical trap lifetimes in high vacuum at high trapping-laser intensity for both annealed and as-grown nanospheres, were used to provide a theoretical analysis of the effects of porosity and non-sphericity in the samples, identifying possible mechanisms of trapping instabilities for nanospheres with non-bulk-silica-like properties.Comment: 10 pages, 7 figure

An apparatus for in-vacuum loading of nanoparticles into an optical trap

We describe the design, construction, and operation of an apparatus utilizing a piezoelectric transducer for in-vacuum loading of nanoparticles into an optical trap for use in levitated optomechanics experiments. In contrast to commonly used nebulizer-based trap-loading methods which generate aerosolized liquid droplets containing nanoparticles, the method produces dry aerosols of both spherical and high-aspect ratio particles ranging in size by approximately two orders of mangitude. The device has been shown to generate accelerations of order $10^7$ $g$, which is sufficient to overcome stiction forces between glass nanoparticles and a glass substrate for particles as small as $170$ nm diameter. Particles with sizes ranging from $170$ nm to $\sim 10$ $\mu$m have been successfully loaded into optical traps at pressures ranging from $1$ bar to $0.6$ mbar. We report the velocity distribution of the particles launched from the substrate and our results indicate promise for direct loading into ultra-high-vacuum with sufficient laser feedback cooling. This loading technique could be useful for the development of compact fieldable sensors based on optically levitated nanoparticles as well as matter-wave interference experiments with ultra-cold nano-objects which rely on multiple repeated free-fall measurements and thus require rapid trap re-loading in high vacuum conditions.Comment: 9 pages, 10 figure