LS-AODV: A ROUTING PROTOCOL BASED ON LIGHTWEIGHT CRYPTOGRAPHIC TECHNIQUES FOR A FANET OF NANO DRONES

With the battlespace rapidly shifting to the cyber domain, it is vital to have secure, robust routing protocols for unmanned systems. Furthermore, the development of nano drones is gaining traction, providing new covert capabilities for operators at sea or on land. Deploying a flying ad hoc network (FANET) of nano drones on the battlefield comes with specific performance and security issues. This thesis provides a novel approach to address the performance and security concerns faced by FANET routing protocols, and, in our case, is specifically tailored to improve the Ad Hoc On-Demand Distance Vector (AODV) routing protocol. The proposed routing protocol, Lightweight Secure Ad Hoc On-Demand Distance Vector (LS-AODV), uses a lightweight stream cipher, Trivium, to encrypt routing control packets, providing confidentiality. The scheme also uses Chaskey-12-based message authentication codes (MACs) to guarantee the authenticity and integrity of control packets. We use a network simulator, NS-3, to compare LS-AODV against two benchmark routing protocols, AODV and the Optimized Link State Routing (OLSR) protocol, in order to gauge network performance and security benefits. The simulation results indicate that when the FANET is not under attack from black-hole nodes, LS-AODV generally outperforms OLSR but performs slightly worse than AODV. On the other hand, LS-AODV emerges as the protocol of choice when a FANET is subject to a black-hole attack.ONROutstanding ThesisLieutenant, United States NavyApproved for public release. Distribution is unlimited

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

Background Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery. Methods This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy. Results Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51–19.97) than planned admissions (OR: 2.32, 95% CI: 1.43–3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8–51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI. Conclusions After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies

Safety of Nonsteroidal Anti-inflammatory Drugs in Major Gastrointestinal Surgery: A Prospective, Multicenter Cohort Study

Background Significant safety concerns remain surrounding the use of nonsteroidal anti-inflammatory drugs (NSAIDs) following gastrointestinal surgery, leading to wide variation in their use. This study aimed to determine the safety profile of NSAIDs after major gastrointestinal surgery. Methods Consecutive patients undergoing elective or emergency abdominal surgery with a minimum one-night stay during a 3-month study period were eligible for inclusion. The administration of any NSAID within 3 days following surgery was the main independent variable. The primary outcome measure was the 30-day postoperative major complication rate, as defined by the Clavien–Dindo classification (Clavien–Dindo III–V). Propensity matching with multivariable logistic regression was used to produce odds ratios (OR) and 95 % confidence intervals. Results From 9264 patients, 23.9 % (n = 2212) received postoperative NSAIDs. The overall major complication rate was 11.5 % (n = 1067). Following propensity matching and adjustment, use of NSAIDs were not significantly associated with any increase in major complications (OR 0.90, 0.60–1.34, p = 0.560). Conclusions Early use of postoperative NSAIDs was not associated with an increase in major complications following gastrointestinal surgery