Abstract: In some aspects, the described systems and methods provide for validating performance of a model trained on a plurality of annotated pathology images. A pathology image is accessed. Frames are generated using the pathology image. Each frame in the set includes a distinct portion of the pathology image. Reference annotations are received from one or more users. The reference annotations describe at least one of a plurality of tissue or cellular characteristic categories for one or more frames in the set. Each frame in the set is processed using the trained model to generate model predictions. The model predictions describe at least one of the tissue or cellular characteristic categories for the processed frame. Performance of the trained model is validated based on determining a degree of association between the reference annotations and the model predictions for each frame and/or across all frames in the set of frames.

Abstract: Apparatus is provided to retrieve tennis balls by attachment to a tennis racket. The apparatus consists of a bracket having a pair of arms positioned between side walls which are affixed to an arcuate base. The arms are pivotable and can be opened to extend upwardly, from the base where they form an opening slightly smaller than the diameter of a tennis ball. The bracket is attached to the top of the tennis racket and will receive tennis balls that are on the ground without the user having to stoop or bend in order to pick the balls up. Once the desired balls have been gathered the arms can be folded back into the bracket where they remain out of the way during play.