165 research outputs found

    Terahertz Antenna Impedance Matched to a Graphene Photodetector

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    Developing low-power, high-sensitivity photodetectors for the terahertz (THz) band that operate at room temperature is an important challenge in optoelectronics. In this study, we introduce a photo-thermal-electric (PTE) effect detector based on quasi-free standing bilayer graphene (BLG) on a silicon carbide (SiC) substrate, designed for the THz frequency range. Our detector's performance hinges on a quasi-optical coupling scheme, which integrates an aspherical silicon lens, to optimize impedance matching between the THz antenna and the graphene p-n junction. At room temperature, we achieved a noise equivalent power (NEP) of less than 300 pW/HzpW/\sqrt{Hz}. Through an impedance matching analysis, we coupled a planar antenna with a graphene p-n junction, inserted in parallel to the nano-gap of the antenna, via two coupling capacitors. By adjusting the capacitors and the antenna arm length, we tailored the antenna's maximum infrared power absorption to specific frequencies. The sensitivity, spectral properties, and scalability of our material make it an ideal candidate for future development of far-infrared detectors operating at room temperature.Comment: 21 pages, 4 figure

    Understanding acute ankle ligamentous sprain injury in sports

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    This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing – a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60–90 ms). The failure supination or inversion torque is about 41–45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not be used as it results in joint stiffness, muscle atrophy and loss of proprioception. Traditional Chinese medicine such as herbs, massage and acupuncture were well applied in China in managing sports injuries, and was reported to be effective in relieving pain, reducing swelling and edema, and restoring normal ankle function. Finally, the best practice of sports medicine would be to prevent the injury. Different previous approaches, including designing prophylactice devices, introducing functional interventions, as well as change of games rules were highlighted. This paper allows the readers to catch up with the previous researches on ankle sprain injury, and facilitate the future research idea on sport-related ankle sprain injury

    Enabling equitable and affordable access to novel therapeutics for pandemic preparedness and response via creative intellectual property agreements

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    The COVID-19 pandemic demonstrated that the current purely market-driven approaches to drug discovery and development alone are insufficient to drive equitable access to new therapies either in preparation for, or in response to, pandemics. A new global framework driven by equity is under negotiation at the World Health Organization to support pandemic preparedness and response. Some believe that the global intellectual property (IP) system itself is part of the problem and propose a purely Open Science approach. In this article, we discuss how existing IP frameworks and contractual agreements may be used to create rights and obligations to generate a more effective global response in future, drawing on experience gained in the COVID Moonshot program, a purely Open Science collaboration, and the ASAP AViDD drug discovery consortium, which uses a hybrid, phased model of Open Science, patent filing and contractual agreements. We conclude that ‘straight to generic’ drug discovery is appropriate in some domains, and that targeted patent protection, coupled with open licensing, can offer a route to generating affordable and equitable access for therapy areas where market forces have failed. The Extended Data contains a copy of our model IP policy, which can be used as a template by other discovery efforts seeking to ensure their drug candidates can be developed for globally equitable and affordable access

    What Tests Are Useful to Investigate a Possible Infection of Total Ankle Arthroplasty (TAA)? What Are Their Thresholds?

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    Recommendation: Overall, the approach to a potentially infected total ankle arthroplasty (TAA) does not change compared to other periprosthetic joint infections (PJIs). There are no novel or unique diagnostic procedures for TAA infection, specifically. Joint aspiration or intraoperative tissue/synovial biopsies with microbiological cultures are the most important diagnostic tests for suspected TAA infections. In the absence of specific data related to TAA, the threshold for these tests should be derived from the hip and knee PJI literature. Level of Evidence: Strong Delegate Vote: Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus) </jats:sec

    What Is the Optimal Protocol for Performing Debridement, Antibiotics and Implant Retention (DAIR) in an Infected Total Ankle Arthroplasty (TAA) (Type and Volume of Irrigation Solution, and so on)?

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    Recommendation: Debridement, antibiotics, and implant retention (DAIR) in acute total ankle arthroplasty (TAA) infections may be an acceptable treatment option. If performed, DAIR should be done meticulously, ensuring that all necrotic or infected tissues are removed and modular parts of the prosthesis, if any, exchanged. The infected joint should also be irrigated with antiseptic solutions. Level of Evidence: Consensus. Delegate Vote: Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus) </jats:sec
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