Solid-state neuromorphic systems based on transistors or memristors have yet to achieve the interconnectivity, performance, and energy efficiency of the brain due to excessive noise, undesirable material properties, and nonbiological switching mechanisms. Here we demonstrate that an alamethicin-doped, synthetic biomembrane exhibits memristive behavior, emulates key synaptic functions including paired-pulse facilitation and depression, and enables learning and computing. Unlike state-of-the-art devices, our two-terminal, biomolecular memristor features similar structure (biomembrane), switching mechanism (ion channels), and ionic transport modality as biological synapses while operating at considerably lower power. The reversible and volatile voltage-driven insertion of alamethicin peptides into an insulating lipid bilayer creates conductive pathways that exhibit pinched current-voltage hysteresis at potentials above their insertion threshold. Moreover, the synapse-like dynamic properties of the biomolecular memristor allow for simplified learning circuit implementations. Low-power memristive devices based on stimuli-responsive biomolecules represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware.

Two-terminal memory elements, or memelements, capable of co-locating signal processing and memory via history-dependent reconfigurability at the nanoscale are vital for next-generation computing materials striving to match the brain’s efficiency and flexible cognitive capabilities. While memory resistors, or memristors, have been widely reported, other types of memelements remain underexplored or undiscovered. Here we report the first example of a volatile, voltage-controlled memcapacitor in which capacitive memory arises from reversible and hysteretic geometrical changes in a lipid bilayer that mimics the composition and structure of biomembranes. We demonstrate that the nonlinear dynamics and memory are governed by two implicitly-coupled, voltage-dependent state variables—membrane radius and thickness. Further, our system is capable of tuneable signal processing and learning via synapse-like, short-term capacitive plasticity. These findings will accelerate the development of low-energy, biomolecular neuromorphic memelements, which, in turn, could also serve as models to study capacitive memory and signal processing in neuronal membranes.

An artificial electrical synapse that mimics the structure, transport properties, and plasticity of biological electrical synapses exhibits voltage-controlled memristance by exploiting reconfigurable membrane geometry.

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Background The principles of global surgery should be taught as a part of the core curriculum in medical schools. The need for medical students to be familiar with the topic is increasing in acceptance. There is, however, a paucity of data on how medical students are exposed to global surgery. This study aims to evaluate exposure of medical students to global surgery, awareness of the key messages of the Lancet Commission on Global Surgery, global surgery career aspirations and barriers to said aspirations. Methods ISOMERS was a multi-centre, online, cross-sectional survey of final year medical students globally. The questionnaire utilised a combination of Likert-scale, multiple-choice, and free text questions. Results In this study, 1593 final year medical students from 144 medical schools in 20 countries participated. The majority (n = 869/1496, 58.1%) believed global surgery to be relevant, despite 17.7% (n = 271/1535) having any exposure to global surgery. Most participants (n = 1187/1476, 80.4%) wanted additional resources on global surgery. Difficulty in providing appropriate care for patients living abroad (n = 854/1242, 68.8%) was the most common perceived barrier to a career in global surgery. Conclusions Participants believed global surgery was a relevant topic for medical students and wanted additional resources that they could access on global surgery. It is critical for medical students to become aware that global surgery is a field that aims to address inequity in surgical care not just internationally, but nationally and locally as well.

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