The TLS Handshake Protocol: A Modular Analysis

We study the security of the widely deployed Secure Session Layer/Transport Layer Security (TLS) key agreement protocol. Our analysis identifies, justifies, and exploits the modularity present in the design of the protocol: the application keys offered to higher-level applications are obtained from a master key, which in turn is derived through interaction from a pre-master key. We define models (following well-established paradigms) that clarify the security level enjoyed by each of these types of keys. We capture the realistic setting where only one of the two parties involved in the execution of the protocol (namely the server) has a certified public key, and where the same master key is used to generate multiple application keys.     

Transmission of hepatitis C virus to infants of human immunodeficiency virus-negative intravenous drug-using mothers: rate of infection and assessment of risk factors for transmission

The acute effects of a newly synthesized thromboxane dual blocker (KDI-792), a combined thromboxane synthase inhibitor and receptor antagonist, on lower limb circulation were examined using two-dimensional color and pulse Doppler ultrasonography and laser Doppler flowmetry. A randomized single-masked, placebo-controlled trial was performed on 36 type 2 diabetic patients with minimally impaired baseline flow. The anatomical cross-sectional area (CSA), maximum flow velocity (MFV) and flow volume index (FVI) in the right dorsal pedis artery (DPA) and right femoral artery (FA) were determined by Doppler ultrasonography before and 45 and 90 minutes after the administration of either 100 or 200 mg of KDI-792 to the dose groups or placebo to the control group. Periflux blood flow (PBF) in the right foot was determined simultaneously by laser Doppler flowmetry. Both CSA and MFV in the dose groups were significantly increased in both the FA and DPA. FVI was markedly increased from 21.4 +/- 3.7 to 68.3 +/- 26.8 in the DPA (M +/- SD, P < 0.01) and from 365.4 +/- 35.3 to 771.7 +/- 75.7 in the FA (P < 0.01) in the 200 mg dose group. In the 100 mg dose group, FVI was markedly increased from 20.0 +/- 8.7 to 68.3 +/- 26.8 (P < 0.01) in the DPA and from 372.5 +/- 130.0 to 677.5 +/- 187.8 (P < 0.01) in the FA. PBF was also increased in both dose groups (from 4.15 +/- 1.4 to 7.0 +/- 4.0 ml/min/100 g tissue in the 200 mg dose group, P < 0.01), whereas there were no significant changes in either measurement in the control group. There were no significant changes in pulse rate or blood pressure after administration in either the dosage group or the placebo group. These and previous findings indicate that a single administration of KDI-792 markedly increases lower limb blood flow and might have a more potent vasodilating effect than that of prostaglandin I2 derivatives.     

Classroom peer acceptance, friendship, and victimization: distinct relational systems that contribute uniquely to children's school adjustment?

The proposition that relationships make differential (i.e., unique, redundant, contingent) contributions to adjustment was examined by investigating the linkages between children's participation in different types of peer relationships (i.e., friendship, peer acceptance, peer victimization) and their adjustment to school. Relationship measures were gathered for 5- to 6-year-old children (105 males, 95 females) twice during kindergarten (i.e., fall and spring) and were correlated with adjustment indicators at each time of assessment and used to predict changes in school adjustment over time. Examination of the relative associations between the relationship measures and children's adjustment revealed evidence of both unshared (i.e., unique) and shared (i.e., redundant) linkages, depending on the form of adjustment examined. These findings suggest that adjustment may be influenced by the diverse experiences (i.e., provisions) that children encounter in different forms of relationship, and that certain types of relationships may have greater or lesser adaptive significance depending on the adjustment outcome examined.     

Continued development of the Nimbus/University of Pittsburgh (UOP) axial flow left ventricular assist system

Nimbus and the University of Pittsburgh (UOP) have continued the development of a totally implanted axial flow blood pump under the National Institutes of Health (NIH) Innovative Ventricular Assist System (IVAS) program. This 62 cc device has an overall length of 84 mm and an outer diameter of 34.5 mm. The inner diameter of the blood pump is 12 mm. It is being designed to be a totally implanted permanent device. A key achievement during the past year was the completion of the Model 2 pump design. Ten of these pumps have been fabricated and are being used to conduct in vitro and in vivo experiments to evaluate the performance of different materials and hydraulic components. Efforts for optimizing the closed loop speed control have continued using mathematical modeling, computer simulations, and in vitro and in vivo testing. New hydraulic blade designs have been tested using computational fluid dynamics (CFD) and flow visualization. A second generation motor was designed with improved efficiency. To support the new motor, a new motor controller fabricated as a surface mount PC board has been completed. The program is now operating under a formal QA system.