Understanding How Reverse Engineers Make Sense of Programs from Assembly Language Representations

This dissertation develops a theory of the conceptual and procedural aspects involved with how reverse engineers make sense of executable programs. Software reverse engineering is a complex set of tasks which require a person to understand the structure and functionality of a program from its assembly language representation, typically without having access to the program\u27s source code. This dissertation describes the reverse engineering process as a type of sensemaking, in which a person combines reasoning and information foraging behaviors to develop a mental model of the program. The structure of knowledge elements used in making sense of executable programs are elicited from a case study, interviews with subject matter experts, and observational studies with software reverse engineers. The results from this research can be used to improve reverse engineering tools, to develop training requirements for reverse engineers, and to develop robust computational models of human comprehension in complex tasks where sensemaking is required

Developing a Framwork for Evaluating Organizational Information Assurance Metrics Programs

The push to secure organizational information has brought about the need to develop better metrics for understanding the state of the organization’s security capability. This thesis utilizes case studies of information security metrics programs within Department of Defense organizations, the United States Air Force (USAF), and the National Aeronautics and Space Administration’s (NASA’s) Jet Propulsion Lab to discover how these organizations make decisions about how the measurement program is designed, how information is collected and disseminated, and how the collected information supports decision making. This research finds that both the DOD and USAF have highly complex information security programs that are primarily focused on determining the return for security investments, meeting budget constraints, and achieving mission objectives while NASA’s Jet Propulsion Lab seeks to improve security processes related to compliance. While the analytical techniques were similar in all of the cases, the DOD and USAF use communication processes still based mostly on manual data calls and communications. In contrast, NASA’s JPL information security metrics program employs a more automated approach for information collection and dissemination

Knee function and neuromuscular adaptations following ACL rupture and reconstruction

In order to alleviate symptoms associated with progressive knee dysfunction and deterioration following anterior cruciate ligament (ACL) injury, patients undergo either conservative non-operative rehabilitative regimens or early reconstructive surgery using the patella tendon (PT) or combined semitendinosus and gracilis tendon (STGT) grafts. Following treatment, ACL deficient (ACLD) and ACL reconstructed (ACLR) patients demonstrate varying levels of knee function with compensatory neuromuscular adaptations thought to be responsible for enhancing the dynamic restraint capabilities in more functional patients. Derivation of the neuromuscular factors that estimate participation restrictions could assist clinicians in developing prognoses and outcome measures for ACLD and ACLR patients. Therefore, the main aim of the present thesis was to identify neuromuscular variables, derived during open and closed kinetic chain tasks, that relate to and predict post ACL injury/ACLR functional outcome. To achieve this, 10 male ACLD subjects together with 27 matched-males who had undergone ACLR (14 PT graft and 13 STGT graft) and 22 matched-control subjects were recruited. In Experiment 1, the Cincinnati Knee Rating System was used to assess knee symptoms and limitations associated with activities of daily living and sports. Three single-leg tests designed to replicate athletic activities were also implemented. Subjective and objective scores were combined to provide an overall knee function score for each subject. The ACLD group was significantly more symptomatic and limited in activities of daily living and sports and they also demonstrated impaired jump and hop performance. Whilst the PT and STGT subjects rated significantly higher than their ACLD counterparts, their average subjective and overall knee function scores were significantly lower compared to the control group. Importantly, graft selection did not significantly influence average subjective, objective or overall knee function scores. In Experiment 2, the effect of ACL injury and ACLR on open kinetic chain isokinetic strength of the quadriceps and hamstrings was assessed in 10o intervals through their operational domain. Antagonist activity of the semitendinosus (ST) and biceps femoris (BF) muscles was also determined during knee extension in 10o intervals between 80 and 10o flexion. Conservatively managed subjects demonstrated significant quadriceps and hamstring weakness with involved limb quadriceps strength deficits transferred to the contralateral limb. Harvesting the central one-third of the PT as an ACL substitute did not inhibit quadriceps strength compared those ACL-insufficient knees in which the extensor mechanism was not used in the reconstruction technique (STGT graft). In contrast, harvesting the flexor mechanism for ACLR caused significant hamstring strength deficits that were not apparent in patients having undergone ACLR using the PT graft. Relatively large amounts of hamstring antagonist activity were evident during knee extension, although ST and BF electromyographic discharge was not influenced by ACL status. Hamstring antagonist activity increased and decreased widely as a function of joint angle with the BF significantly more active than the ST in order to control internal tibial rotation. Kinesthetic joint capsule receptors were thought to be the major source dictating hamstring muscle activity in such a manner that it varied nearly inversely relative to its moment arm. In Experiment 3, lower limb kinematics, kinetics and neuromuscular responses were assessed in ACLD and ACLR subjects during a closed kinetic chain task known to stress the ACL, namely abrupt deceleration when landing from a single-leg hop for distance. For the ACLD group, no significant alterations were evident in joint kinematic parameters. Biceps femoris of the involved limb of the ACLD group was activated significantly later compared to the non-involved limb, supporting the notion that after ACL injury, sensory feedback may be used to build a new internal model depicting the expected conditions during functional activities. The involved limb of the ACLD and ACLR groups demonstrated a significant reduction in vertical ground reaction force during the support phase of landing compared to the non-involved limb. Whilst the magnitude of peak tibial acceleration was not significantly different between test limbs or subject groups, it took significantly longer for the involved limb of the ACLD and ACLR groups to attain constant tibial motion compared to the non-involved limb. Subjects having undergone ACLR using the PT graft demonstrated a stiff knee strategy during landing and, whilst the STGT group also demonstrated trends towards decreased knee flexion during landing, no significant kinematic adaptations at the hip, knee or ankle were identified. Decreased knee flexion was found to significantly attenuate the mechanical advantage of the involved limb hamstrings of the ACLD, PT and STGT groups. Cumulative changes in involved limb hip and knee kinematics of the ACLD and ACLR subjects meant that the ST and BF muscles were significantly elongated when decelerating to improve dynamic restraint. Importantly, ACLR led to a restoration of normal quadriceps and hamstring electromyographic (EMG) synchrony in the involved and contralateral limbs and there was no evidence to suggest that the ACLD subjects adopted a pattern of quadriceps-avoidance. In Experiment 4, the strength of the associations among knee functionality of ACLD and ACLR subjects (Experiment 1) and neuromuscular variables derived from open (Experiment 2) and closed (Experiment 3) kinetic chain movements was determined. Numerous significant moderate to strong correlations were identified with determinants of knee functionality related to the type of ACL treatment and graft selection. Compensatory neuromuscular strategies that enhance function in the ACLD knee included amplified hamstring co-activation, increased hamstring preparatory activity and a greater ability to control tibial motion during dynamic deceleration. Following ACL replacement, the degree of residual strength deficit in the muscle from which the tendon graft was harvested (i.e. quadriceps or hamstrings) become an important prognosticator of knee functionality as did attenuated hamstring co-activation during knee extension within the range utilsed during single-limb deceleration. More functional PT subjects demonstrated enhanced tibial control whilst superior knee functionality in STGT subjects was associated with increased preparatory activity of the quadriceps when landing on the involved limb. Furthermore, by synchronising peak hamstring muscle activity at the time when the ACL graft is most vulnerable to injury, more functional STGT subjects enhanced dynamic restraint by increasing joint compression and posterior tibial drawer. By identifying neuromuscular factors that predict function in ACLD and ACLR subjects, the results of these studies will lead to the development of more specific and effective treatment strategies

Regulator of G Protein Signaling-21 (RGS21) in Peripheral Taste Physiology.

The gustatory system subjects ingested food to ‘quality control’ that prevents consumption of harmful compounds while also regulating nutrient intake. A better understanding of the physiological regulation of taste will enhance our ability to facilitate the appropriate consumption of nutrients and improve overall health. Bitter, sweet, and umami tastes are detected by a family of G protein-coupled receptors (GPCRs) that associate with heterotrimeric G proteins and initiate intracellular signaling cascades after activation by tastant binding. ‘Regulators of G protein Signaling’ (RGS proteins) act as Ga-directed GTPase-accelerating proteins (GAPs) and thereby accelerate inactivation of GPCR-mediated signaling. Rgs21 is selectively expressed in tastantresponsive tissue, suggesting it likely facilitates the inactivation of the taste transduction pathway. We have assessed taste responses in Rgs21 knockout mice: bitterant, sweetener, and umami responses (metabotropic, Type II cell responses) are blunted in the absence of RGS21, whereas aversion to sour (ionotropic, Type III cell response) is unchanged. Notably, appetitive responses to NaCl are blunted in Rgs21-deficient mice as well, suggesting transduction of NaCl taste involves a GPCR and/or G protein signaling in Type II taste receptor cells. We suspect that RGS21 loss leads to hyperactivity of GPCRs in taste receptor cells, eventually causing prolonged desensitization and/or downregulation. Further work is needed to test this hypothesis and thus elucidate the mechanism(s) by which RGS21 affects peripheral taste signaling, including appetitive salt taste (a taste modality traditionally considered the exclusive domain of ionotropic signal transduction)

Tibial acceleration variability during consecutive gait cycles is influenced by the menstrual cycle

Background: The relationship between the phases of the menstrual cycle and injury risk remains unclear. Neuromuscular function may be compromised during menstruation, which could result in reduced cyclicality of movement patterns. We hypothesize that mediolateral (varus/valgus) knee acceleration during running gait will possess increased variability during menstruation when compared to ≈ ovulation in women who do not take the monophasic oral contraceptive pill (MOCP). Methods: Thirty-six women (18 MOCP users: MOCP group and 18 non-pill users: NP group) performed six-minute treadmill running trials at 10 km h- 1 with an accelerometer fixed to the proximal tibia. Trials were performed at menstruation and ≈ ovulation (for the MOCP group at a similar stage of the cycle) in a randomized order. The cyclicality of gross mediolateral tibial acceleration during 15 consecutive strides was assessed using combined wavelet and autocorrelation analysis. Longitudinal and anteroposterior accelerations were also examined. Repeated measures analysis of variance (ANOVA) tests were performed to assess differences at each stage of the menstrual cycle (α = 0.05). Findings: Gross mediolateral acceleration in the NP group had significantly (P = 0.022) increased variability at the time of menstruation compared to ≈ ovulation, and was also significantly (P = 0.011) more variable than the MOCP group at the corresponding time point. No significant difference was observed for any measure in the MOCP group. Interpretation: Increased variability in the NP users at menstruation may be a result of compromised motor control strategies. This provides further evidence of variability in performance and motor control during menstruation, and may have implications for a female athlete's risk of injury. © 2010 Elsevier Ltd. All rights reserved

Accuracy of acetabular cup positioning using imageless navigation

Background: Correct placement of the acetabular cup is a crucial step in total hip replacement to achieve a satisfactory result and remains a challenge with free-hand techniques. Imageless navigation may provide a viable alternative to free-hand technique and improve placement significantly. The purpose of this project was to assess and validate intra-operative placement values for both inclination and anteversion as displayed by an imageless navigation system to post-operative measurement of cup position using high resolution CT scans

Towards an expert system for enantioseparations: induction of rules using machine learning

A commercially available machine induction tool was used in an attempt to automate the acquisition of the knowledge needed for an expert system for enantioseparations by High Performance Liquid Chromatography using Pirkle-type chiral stationary phases (CSPs). Various rule-sets were induced that recommended particular CSP chiral selectors based on the structural features of an enantiomer pair. The results suggest that the accuracy of the optimal rule-set is 63% + or - 3% which is more than ten times greater than the accuracy that would have resulted from a random choice

A review of expert systems for chromatography

Expert systems for chromatography are reviewed. A taxonomy is proposed that allows present (and future) expert systems in this area to be classified and facilitates an understanding of their inter-relationship. All the systems are described focusing on the reasons for their development, what their purpose was and how they were to be used. The engineering methods, knowledge representations, tools and architectures used for the systems are compared and contrasted in a discussion covering all the stages of the development life cycle of expert systems. The review reveals that too often developers of expert systems for chromatography do not justify their decisions on engineering matters and that the literature suggests that many ideas advocated by knowledge engineers are not being used