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Metasurfaces have been used to realize optical functions such as focusing and beam steering. They use subwavelength nanostructures to control the local amplitude and phase of light. Here we show that such control could also enable a new function of artificial neural inference. We demonstrate that metasurfaces can directly recognize objects by focusing light from an object to different spatial locations that correspond to the class of the object.
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Abstract Incurable breast cancer bone metastasis causes widespread bone loss, resulting in fragility, pain, increased fracture risk, and ultimately increased patient mortality. Increased mechanical signals in the skeleton are anabolic and protect against bone loss, and they may also do so during osteolytic bone metastasis. Skeletal mechanical signals include interdependent tissue deformations and interstitial fluid flow, but how metastatic tumor cells respond to each of these individual signals remains underinvestigated, a barrier to translation to the clinic. To delineate their respective roles, we report computed estimates of the internal mechanical field of a bone mimetic scaffold undergoing combinations of high and low compression and perfusion using multiphysics simulations. Simulations were conducted in advance of multimodal loading bioreactor experiments with bone metastatic breast cancer cells to ensure that mechanical stimuli occurring internally were physiological and anabolic. Our results show that mechanical stimuli throughout the scaffold were within the anabolic range of bone cells in all loading configurations, were homogenously distributed throughout, and that combined high magnitude compression and perfusion synergized to produce the largest wall shear stresses within the scaffold. These simulations, when combined with experiments, will shed light on how increased mechanical loading in the skeleton may confer anti‐tumorigenic effects during metastasis.
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Perfusion applied to a 3D model of bone metastasis results in uniformly dispersed mechanical stimuli
Abstract Breast cancer most frequently metastasizes to the skeleton. Bone metastatic cancer is incurable and induces wide‐spread bone osteolysis, resulting in significant patient morbidity and mortality. Mechanical cues in the skeleton are an important microenvironmental parameter that modulate tumor formation, osteolysis, and tumor cell‐bone cell signaling, but which mechanical signals are the most beneficial and the corresponding molecular mechanisms are unknown. We focused on interstitial fluid flow based on its well‐known role in bone remodeling and in primary breast cancer. We created a full‐scale, microCT‐based computational model of a 3D model of bone metastasis undergoing applied perfusion to predict the internal mechanical environment during in vitro experimentation. Applied perfusion resulted in uniformly dispersed, heterogeneous fluid velocities, and wall shear stresses throughout the scaffold's interior. The distributions of fluid velocity and wall shear stress did not change within model sub‐domains of varying diameter and location. Additionally, the magnitude of these stimuli is within the range of anabolic mechanical signals in the skeleton, verifying that our 3D model reflects previous in vivo studies using anabolic mechanical loading in the context of bone metastasis. Our results indicate that local populations of cells throughout the scaffold would experience similar mechanical microenvironments.