Existing research on Content Delivery Networks (CDNs) predominantly focuses on optimizing the delivery of hot content—popular items that attract frequent and repeated access from large user bases. However, at Meta, we have identified that cold content, which is less popular and accessed infrequently, poses significant challenges for user experience, especially with large volumes of direct messaging media. Through extensive analysis of Meta's CDN data, we quantify the impact of cold content performance on user experience and reveal substantial differences across geographic regions. Motivated by these findings, we propose CacheFlare, a suite of production-deployed solutions designed to enhance Quality of Experience (QoE) by increasing CDN hit rates for cold content. Through experiments and production validation, we show that even cold content can benefit from improved caching strategies, yielding up to a 10% improvement across a range of network performance metrics.

Wings of insects are flexible structures. Although there has been much recent progress in the area of insect flight aerodynamics, very little is known about how wing flexibility influences aerodynamic forces during flapping flight. We investigated this question using a dynamically scaled mechanical model of insect wings. Using a suite of wings with varying flexural stiffness (EI) values, we generated aerodynamic polar plots to characterize the force coefficients of flexible wings. These polar plots showed that the aerodynamic performance of the wings varied with wing flexibility. In general, aerodynamic force production decreased with increasing flexibility. Both lift and drag coefficients of wings are greater when wings are more rigid. However, at very high angles of attack, flexible wings generated greater lift than a rigid wing. In addition, the ratio of lift-to-drag also decreased with increasing flexibility. These data show that flexible wings offer no aerodynamic advantage over a rigid wing under steady state circumstances. Because wing material in insects is usually flexible but reinforced by wing veins, we tested the hypothesis that wing veins enhance the aerodynamic performance of wings by increasing their effective stiffness. Our data suggests that even a very basic framework of appropriately placed wing veins can substantially increase the functional rigidity of the wings thereby enhancing its aerodynamic performance.