A topological mechanism for robust and efficient global oscillations in biological networks.

Long and stable timescales are often observed in complex biochemical networks, such as in emergent oscillations. How these robust dynamics persist remains unclear, given the many stochastic reactions and shorter time scales demonstrated by underlying components. We propose a topological model that produces long oscillations around the network boundary, reducing the system dynamics to a lower-dimensional current in a robust manner.

A topological fluctuation theorem.

Fluctuation theorems specify the non-zero probability to observe negative entropy production, contrary to a naive expectation from the second law of thermodynamics. For closed particle trajectories in a fluid, Stokes theorem can be used to give a geometric characterization of the entropy production. Building on this picture, we formulate a topological fluctuation theorem that depends only by the winding number around each vortex core and is insensitive to other aspects of the force.

Oro-pharyngo-esophageal radionuclide scintigraphy predicts aspiration pneumonia risk and associated survival in post-irradiated nasopharyngeal carcinoma patients.

Objective: To demonstrate that oro-pharyngo-esophageal radionuclide scintigraphy (OPERS) not only detects tracheobronchial aspiration after swallowing, but also quantifies the amount of aspiration and subsequent clearance.

Methods: Data collected between 2014 and 2019 were reviewed for aspiration pneumonia at 12 and 24-months after OPERS. The predictive value for aspiration pneumonia on flexible endoscopic evaluation of swallowing (FEES), videofluoroscopic swallowing study (VFSS), and OPERS, and the overall survival of patients with or without aspiration were determined.

Control of brain network dynamics across diverse scales of space and time.

The human brain is composed of distinct regions that are each associated with particular functions and distinct propensities for the control of neural dynamics. However, the relation between these functions and control profiles is poorly understood, as is the variation in this relation across diverse scales of space and time. Here we probe the relation between control and dynamics in brain networks constructed from diffusion tensor imaging data in a large community sample of young adults.

International Microsurgery Club: An Effective Online Collaboration System.

Background:  This study aimed to determine if International Microsurgery Club (IMC) is an effective online resource for microsurgeons worldwide, in providing an avenue for timely group discussions and advice regarding complicated cases, and an avenue for collaboration and information sharing.

Methods:  All posts on the IMC Facebook group from member 1 to 8,000 were analyzed according to inclusion criteria and categorized into three categories-case discussion, question, and information sharing. Posts were retrospectively analyzed for number of responses, time of responses, number of "likes," number of treatment options, time of day, and demographics of authors and responders.

The Preferred Management of a Single-Digit Distal Phalanx Amputation.

Background:  Replantation of a single digit at the distal phalanx level is not routinely performed since it is technically challenging with questionable cost-effectiveness. The purpose of this study was to analyze international microsurgeons' clinical decisions when faced with this common scenario.

Methods:  A survey of a right-middle finger distal phalanx transverse complete amputation case was conducted via online and paper questionnaires.

Can a Partially Injured Donor Nerve Restore Elbow Flexion in an Acute Brachial Plexus Injury in Rats?

Background: Loss of elbow flexion commonly occurs following acute brachial plexus injury. The double fascicular transfer is often used in acute C5-C6 and C5-C7 root injuries, but is rarely applied in cases involving concomitant C8 or T1 root injury. The authors designed a rat model using varying severities of lower trunk injury to determine whether partial injury to the lower trunk affects nerve transfers for elbow flexion.

Effective learning is accompanied by high-dimensional and efficient representations of neural activity.

A fundamental cognitive process is to map value and identity onto the objects we learn about. However, what space best embeds this mapping is not completely understood. Here we develop tools to quantify the space and organization of such a mapping in neural responses as reflected in functional MRI, to show that quick learners have a higher dimensional representation than slow learners, and hence more easily distinguishable whole-brain responses to objects of different value.

Impact of Social Media on Current Medical Conferences.

Background:  Medical conferences are forums for research, continuing medical education, and networking. Social media is increasingly used for communication and networking due to its low cost and ability to overcome large distances. This study investigates the impact that social media brings to the current conference system.

Sex differences in network controllability as a predictor of executive function in youth.

Executive function is a quintessential human capacity that emerges late in development and displays different developmental trends in males and females. Sex differences in executive function in youth have been linked to vulnerability to psychopathology as well as to behaviors that impinge on health, wellbeing, and longevity. Yet, the neurobiological basis of these differences is not well understood, in part due to the spatiotemporal complexity inherent in patterns of brain network maturation supporting executive function.

Developmental increases in white matter network controllability support a growing diversity of brain dynamics.

As the human brain develops, it increasingly supports coordinated control of neural activity. The mechanism by which white matter evolves to support this coordination is not well understood. Here we use a network representation of diffusion imaging data from 882 youth ages 8-22 to show that white matter connectivity becomes increasingly optimized for a diverse range of predicted dynamics in development.

Interacting one-dimensional fermionic symmetry-protected topological phases.

In free fermion systems with given symmetry and dimension, the possible topological phases are labeled by elements of only three types of Abelian groups, 0, Z2, or Z. For example, noninteracting one-dimensional fermionic superconducting phases with S(z) spin rotation and time-reversal symmetries are classified by Z. We show that with weak interactions, this classification reduces to Z4.

High-temperature fractional quantum Hall states.

We show that a suitable combination of geometric frustration, ferromagnetism, and spin-orbit interactions can give rise to nearly flatbands with a large band gap and nonzero Chern number. Partial filling of the flatband can give rise to fractional quantum Hall states at high temperatures (maybe even room temperature). While the identification of material candidates with suitable parameters remains open, our work indicates intriguing directions for exploration and synthesis.