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. RESULTS: A retrospective analysis of 531 cases showed an average response rate of 75.7% within 1 hour and as membership grew. The response rate stabilized averaging between 72.5 and 78% across all times of the day. An average of 11.8 microsurgeons was involved per case discussion, and 5.7 treatment options were provided per case. CONCLUSION: IMC is shown to be an effective resource to allow microsurgeons to access timely advice from other microsurgeons without time and distance limitation, and to have interactive group discussions on complicated cases.

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. Microsurgeons around the world were invited to provide their treatment recommendations. In total, 383 microsurgeons replied, and their responses were stratified and analyzed by geographical areas, specialties, microsurgery fellowship training, and clinical experiences. RESULTS: Among 383 microsurgeons, 170 (44.3%) chose replantation as their preferred management option, 137 (35.8%) chose revision amputation, 62 (16.2%) chose local flap coverage, 8 (2.1%) chose composite graft, and 6 (1.6%) favored other choices as their reconstruction method for the case study. Microsurgeons from the Asia-Pacific, Middle East/South Asia, and Central/South America regions tend to perform replantation (70.7, 68.8, and 67.4%, respectively) whereas surgeons from North America and Europe showed a lower preference toward replantation (20.5 and 26.8%, respectively p < 0.001). Having completed a microsurgery fellowship increased the attempt rate of replantation by 15.3% (p = 0.004). Clinical experience and the surgeons' specialties did not show statistical significance in clinical decision making. CONCLUSION: From the present study, the geographic preferences and microsurgery fellowship experience influence the method of reconstruction for distal phalanx amputation. Multiple factors are taken into consideration in selecting the most suitable reconstructive method for each case scenario. In addition to the technical challenges of the proposed surgery, the cost of the procedure and the type of facility needed are important variables in the decision making process.

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. Here we test the hypothesis that sex differences in impulsivity in youth stem from sex differences in the controllability of structural brain networks as they rewire over development. Combining methods from network neuroscience and network control theory, we characterize the network control properties of structural brain networks estimated from diffusion imaging data acquired in males and females in a sample of 879 youth aged 8-22 years. We summarize the control properties of these networks by estimating average and modal controllability, two statistics that probe the ease with which brain areas can drive the network towards easy versus difficult-to-reach states. We find that females have higher modal controllability in frontal, parietal, and subcortical regions while males have higher average controllability in frontal and subcortical regions. Furthermore, controllability profiles in males are negatively related to the false positive rate on a continuous performance task, a common measure of impulsivity. Finally, we find associations between average controllability and individual differences in activation during an n-back working memory task. Taken together, our findings support the notion that sex differences in the controllability of structural brain networks can partially explain sex differences in executive function. Controllability of structural brain networks also predicts features of task-relevant activation, suggesting the potential for controllability to represent context-specific constraints on network state more generally.

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. METHODS: There are three parts of this study: (1) comparing two similar brachial plexus injuries (BPIs) courses without (2009) and with (2017) social media support, and the participants' feedback; (2) sharing our experiences in the management of the 2018 International Course on SuperMicrosurgery (ICSM) conference; and (3) evaluating the studies from the social media platform International Microsurgery Club (IMC), for the consensus pertaining to social media and conference system. RESULTS: With the help of social media, international attendance increased during the 2017 BPI conference compared with the 2009 BPI course (25 nationalities in 2009 vs. 35 in 2017). At least 23% obtained their meeting information through social media. Live surgery was the overall main attraction (79%). The 2018 ICSM meeting revealed that video posts increased attendance; videos that were the most effective in attracting (viewership) were either short or pertained to surgical procedures. Facebook, Messenger, and WeChat smartphone applications were effective for immediate communication and troubleshooting among the participants. From the IMC polls, 78% believe that the social media and the conference complemented each other. 97% attended the conference to update their skills and knowledge. CONCLUSION: Social media is a quick and economic tool in promoting medical conferences and instant messenger systems offer immediate communication amongst associates. Despite the popularity of social media, the conference still has its irreplaceable role. The combination of the conference and the social media enhances the training and education of microsurgeons.

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. Using this to model KaiC, which regulates the circadian rhythm in cyanobacteria, we compare the coherence of oscillations to that in other KaiC models. Our topological model localizes currents on the system edge, with an efficient regime of simultaneously increased precision and decreased cost. Further, we introduce a new predictor of coherence from the analysis of spectral gaps, and show that our model saturates a global thermodynamic bound. Our work presents a new mechanism and parsimonious description for robust emergent oscillations in complex biological networks.

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. Using group cohomology, one can additionally show that there are only four distinct phases for such one-dimensional superconductors even with strong interactions. Comparing their projective representations, we find that all these four symmetry-protected topological phases can be realized with free fermions. Further, we show that one-dimensional fermionic superconducting phases with Z(n) discrete S(z) spin rotation and time-reversal symmetries are classified by Z4 when n is even and Z2 when n is odd; again, all these strongly interacting topological phases can be realized by noninteracting fermions. Our approach can be applied to systems with other symmetries to see which one-dimensional topological phases can be realized with free fermions.

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. The probability is robust to local deformations of the particle trajectory, reminiscent of topologically protected modes in various classical and quantum systems. We demonstrate that entropy production is quantized in these strongly fluctuating systems, and it is controlled by a topological invariant. We demonstrate that the theorem holds even when the probability distributions are non-Gaussian functions of the generated heat.

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. RESULTS: Thirty-seven patients treated with radiotherapy for nasopharyngeal carcinoma (NPC) were reviewed. The incidence of aspiration detected on FEES, VFSS, and OPERS was 78.4%, 66.7%, and 44.4%, respectively. Using VFSS as a gold standard, the sensitivity and specificity of OPERS for aspiration was 73.7% and 100%. The positive and negative predictive values for aspiration were 100% and 66.7%, respectively, with an overall accuracy of 82.8%. A history of aspiration pneumonia was one factor associated with a higher chance of subsequent aspiration pneumonia within 12 months (odds ratio: 15.5, 95% CI 1.67-145.8, p < .05) and 24 months (odds ratio: 23.8, 95% CI 3.69-152.89, p < .01) of the swallowing assessment. Aspiration detected by OPERS was a significant risk factor for future aspiration pneumonia at 12 and 24 months respectively. Significantly, better survival was associated with an absence of aspiration on OPERS only, but not on FEES or VFSS. CONCLUSION: OPERS predicts the safety of swallowing, the incidence of subsequent aspiration pneumonia, and the survival prognosis in post-irradiated NPC dysphagia patients. LEVEL OF EVIDENCE: 3.

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.

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. Specifically, we probe the control properties of each brain region and investigate their relationship with dynamics across various spatial scales using the Laplacian eigenspectrum. In addition, through analysis of regional modal controllability and partitioning of modes, we determine whether the associated dynamics are fast or slow, as well as whether they are alternating or monotone. We find that brain regions that facilitate the control of energetically easy transitions are associated with activity on short length scales and slow timescales. Conversely, brain regions that facilitate control of difficult transitions are associated with activity on long length scales and fast timescales. Built on linear dynamical models, our results offer parsimonious explanations for the activity propagation and network control profiles supported by regions of differing neuroanatomical structure.

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. Furthermore, we find that quick learners display more compact embedding of their neural responses, and hence have higher ratios of their stimuli dimension to their embedding dimension, which is consistent with greater efficiency of cognitive coding. Lastly, we investigate the neurophysiological drivers at smaller scales and study the complementary distinguishability of whole-brain responses. Our results demonstrate a spatial organization of neural responses characteristic of learning and offer geometric measures applicable to identifying efficient coding in higher-order cognitive processes.

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. METHODS: There were four different rat groups in which 0, 25, 75, or 100 percent of the donor lower trunk remained intact. One-fourth of the cross-sectional area of the ulnar nerve was then transferred to the musculocutaneous nerve immediately. The authors assessed outcomes using a grooming test, muscle mass, retrograde labeling of sensory/motor neurons that regenerated axons, and immunohistochemical stain of regenerated axons. RESULTS: Five months after nerve transfer, rats that underwent partial injury of the lower trunk fared significantly worse than the rats in whom the donor lower trunk remained 100 percent intact, but significantly better than the rats with 0 percent intact lower trunk. Rats with 25 or 75 percent of the lower trunk intact recovered equivalent function, at both the donor and recipient sites. CONCLUSIONS: Although relatively weak compared with the 100 percent intact donor lower trunk group, the partially injured donor nerve was still functional; even though the nerve sustained a partial injury, the residual axons reinnervated the target muscles. The power of the muscles following either 25 percent or 75 percent injuries was equal after the recovery. Resorting to this approach may be useful in cases in which no alternatives are available.

Tips for Making a Successful Online Microsurgery Educational Platform: The Experience of International Microsurgery Club.

The presence of online learning resources has grown tremendously in recent years. They provide powerful and yet easily accessible means of learning and sharing knowledge. Online learning resources now encompass all aspects of medicine, and microsurgery is no exception. International Microsurgery Club is a closed, invitation-only group based on the Facebook social media platform. It was initiated on May 6, 2016, with the primary objectives of providing a convenient forum for discussing challenging cases, sharing valuable resources, and providing opportunities for research collaboration. The membership of International Microsurgery Club has grown to over 8700 at 2 years' existence, and continues to expand. International Microsurgery Club has become one of the largest online platforms for global microsurgeons. Here, the authors share their experience on how to establish a successful online platform for medical education.

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. Notably, stable controllers in subcortical areas are negatively related to cognitive performance. Investigating structural mechanisms supporting these changes, we simulate network evolution with a set of growth rules. We find that all brain networks are structured in a manner highly optimized for network control, with distinct control mechanisms predicted in child vs. older youth. We demonstrate that our results cannot be explained by changes in network modularity. This work reveals a possible mechanism of human brain development that preferentially optimizes dynamic network control over static network architecture.