Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable view of the chest is compared to previous exam from ___ . Linear opacity again seen at the left lung base suggestive of atelectasis . Lateral costophrenic angles , however , are now sharp . Cardiomediastinal silhouette is within normal limits . Degenerative changes are noted at the glenohumeral joint on the left . Old posterior right 8th rib fracture is again seen .
    OUTPUT:
    
No acute cardiopulmonary process .