A hierarchical protocol for increasing the stealthiness of steganographic methods

We present a new protocol that works in conjunction with information hiding algorithms to systematically improve their stealthiness. Our protocol is designed to work with many digital object types including natural language text, software, images, audio, or streaming data. It utilizes a treestructured hierarchical view of the cover object and determines regions where changes to the object for embedding message data would be easily revealed by an attacker, and are thus to be avoided by the embedding process. The protocol requires the existence of a heuristic detectability metric which can be calculated over any region of the cover object and whose value correlates with the likelihood that a steganalysis algorithm would classify that region as one with embedded information. By judiciously spreadin

Effectiveness of Palatal Mucosa Graft in Surgical Treatment of Sub-Glottic Stenosis.

OBJECTIVES: Mucosal free grafts may be successfully applied in many surgical interventions. This study aims at investigating the feasibility of palatal mucosa graft in sub-glottic field in an animal model. METHODS: This randomized prospective controlled study was conducted with an animal model. Sub-glottic inflammation was created in 15 adult rabbits in each group and sub-glottic stenosis surgery was applied thereafter. The rabbits in group 1 (control group) underwent segmental resection, partial cricoidectomy, and trachea-thyroid cartilage anastomosis; the rabbits in group 2 underwent segmental resection, cricoplasty, and crico-tracheal anastomosis using free buccal mucosa graft; and the rabbits in group 3 underwent segmental resection, cricoplasty, and crico-tracheal anastomosis using free palatal mucosa graft. Re-stenosis was evaluated after 42 days. RESULTS: The percentages of stenosis were 27%±20%, 40%±20%, and 34%±23% for group 1, 2, and 3, respectively and the difference was not statistically significant (P=0.29). Intensive and tight fibrosis was observed in 2 rabbits (13%) in group 1, in 5 rabbits (33%) in group 2, and in 3 rabbits (20%) in group 3. There was not a statistically significant difference between groups (P=0.41). Excessive inflammation was observed in 3 rabbits (20%) in group 1, in 7 rabbits (47%) in group 2, and 3 rabbits (20%) in group 3. There was no a statistically significant difference between groups although inflammation rate was higher in the rabbits which underwent buccal mucosa graft (P=0.18). CONCLUSION: The surgical treatments applied with free mucosa graft reduced anastomosis tension through enabling anastomosis to the distal of cricoid instead of thyroid cartilage. Free palatal mucosa grafts may be used in sub-glottic field, one of the most challenging fields of trachea surgery, due to ease of application and rapid vascularization