RESUMEN
A compact near-eye visor (NEV) system that can guide light from a display to the eye could transform augmented reality (AR) technology. Unfortunately, existing implementations of such an NEV either suffer from small field of view or chromatic aberrations. See-through quality and bulkiness further make the overall performance of the visors unsuitable for a seamless user experience. Metasurfaces are an emerging class of nanophotonic elements that can dramatically reduce the size of optical elements while enhancing functionality. In this paper, we present a design of composite metasurfaces for an ultracompact NEV. We simulate the performance of a proof-of-principle visor corrected for chromatic aberrations while providing a large display field of view (>77∘ both horizontally and vertically) and good see-through quality [>70% transmission and less than a wavelength root mean-square (RMS) wavefront error over the whole visible wavelength range] as needed for an immersive AR experience.
RESUMEN
A free-radical approach has enabled the development of a synthetically versatile alkyl-(hetero)arylation of olefins. Alkyl and (hetero)aryl groups were added concurrently to a full suite of mono- to tetrasubstituted simple alkenes (i.e., without requiring directing or electronically activating groups) for the first time. Key advances also included the introduction of synthetically diversifiable alkyl groups featuring different degrees of substitution, good diastereocontrol in both cyclic and acyclic settings, the addition of biologically valuable heteroarenes featuring Lewis basic nitrogen atoms as well as simple benzenes, and the generation of either tertiary or quaternary benzylic centers. The synthetic potential of this transformation was demonstrated by leveraging it as the key step in a concise synthesis of oliceridine, a new painkiller that received FDA approval in 2020.
RESUMEN
OBJECTIVES: This study compared the clinical performance of the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC) for detecting any traumatic intracranial lesion on computed tomography (CT) in patients with a Glasgow Coma Scale (GCS) score of 15. Also assessed were ability to detect patients with "clinically important" brain injury and patients requiring neurosurgical intervention. Additionally, the performance of the CCHR was assessed in a larger cohort of those presenting with GCS of 13 to 15. METHODS: This prospective cohort study was conducted in a U.S. Level I trauma center and enrolled a consecutive sample of mildly head-injured adults who presented to the emergency department (ED) with witnessed loss of consciousness, disorientation or amnesia, and GCS 13 to 15. The rules were compared in the group of patients with GCS 15. The primary outcome was prediction of "any traumatic intracranial injury" on CT. Secondary outcomes included "clinically important brain injury" on CT and need for neurosurgical intervention. RESULTS: Among the 431 enrolled patients, 314 patients (73%) had a GCS of 15, and 22 of the 314 (7%) had evidence of a traumatic intracranial lesion on CT. There were 11 of 314 (3.5%) who had "clinically important" brain injury, and 3 of 314 (1.0%) required neurosurgical intervention. The NOC and CCHR both had 100% sensitivity (95% confidence interval [CI] = 82% to 100%), but the CCHR was more specific for detecting any traumatic intracranial lesion on CT, with a specificity of 36.3% (95% CI = 31% to 42%) versus 10.2% (95% CI = 7% to 14%) for NOC. For "clinically important" brain lesions, the CCHR and the NOC had similar sensitivity (both 100%; 95% CI = 68% to 100%), but the specificity was 35% (95% CI = 30% to 41%) for CCHR and 9.9% (95% CI = 7% to 14%) for NOC. When the rules were compared for predicting need for neurosurgical intervention, the sensitivity was equivalent at 100% (95% CI = 31% to 100%) but the CCHR had a higher specificity at 80.7% (95% CI = 76% to 85%) versus 9.6% (95% CI = 7% to 14%) for NOC. Among all 431 patients with a GCS score 13 to 15, the CCHR had sensitivities of 100% (95% CI = 84% to 100%) for 27 patients with clinically important brain injury and 100% (95% CI = 46% to 100%) for five patients requiring neurosurgical intervention. CONCLUSIONS: In a U.S. sample of mildly head-injured patients, the CCHR and the NOC had equivalently high sensitivities for detecting any traumatic intracranial lesion on CT, clinically important brain injury, and neurosurgical intervention, but the CCHR was more specific. A larger cohort will be needed to validate these findings.