def get_evidence_for_item(search_results, item):
    """
    Get evidence fields with positive scores for a particular search result 
    item.
    """
    if search_results.get('evidence', None) is None:
        return []
    item_evidence = []
    for i, score in enumerate(item['scores']):
        if score > 0:
            evidence = search_results['evidence'][i]
            evidence['score'] = score
            item_evidence.append(evidence)
    return item_evidence