Viking Orbiter 1975 thrust vector control system accuracy

The thrust vector control (TVC) system of the Viking Orbiter 1975 is discussed. The purpose of the TVC system is to point the engine thrust at the vehicle center of mass and to maintain attitude stability during propulsive maneuvers. This is accomplished by mounting the engine in a two-axis gimbal system. The TVC system then controls the pointing of the engine by closed loop control of two linear actuators which extend or retract and rotate the engine in its gimbal system. The effect of the TVC on the velocity vector pointing error incurred during a propulsive maneuver is analyzed. Models for predicting the magnitude of the error for various propulsive maneuvers are developed

Effects of OEF/OIF-Related Physical and Emotional Co-Morbidities on Associative Learning: Concurrent Delay and Trace Eyeblink Classical Conditioning

This study examined the performance of veterans and active duty personnel who served in Operation Enduring Freedom and/or Operation Iraqi Freedom (OEF/OIF) on a basic associative learning task. Eighty-eight individuals participated in this study. All received a comprehensive clinical evaluation to determine the presence and severity of posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI). The eyeblink conditioning task was composed of randomly intermixed delay and trace conditioned stimulus (CS) and unconditioned stimulus (US) pairs (acquisition) followed by a series of CS only trials (extinction). Results revealed that those with a clinical diagnosis of PTSD or a diagnosis of PTSD with comorbid mTBI acquired delay and trace conditioned responses (CRs) to levels and at rates similar to a deployed control group, thus suggesting intact basic associative learning. Differential extinction impairment was observed in the two clinical groups. Acquisition of CRs for both delay and trace conditioning, as well as extinction of trace CRs, was associated with alcoholic behavior across all participants. These findings help characterize the learning and memory function of individuals with PTSD and mTBI from OEF/OIF and raise the alarming possibility that the use of alcohol in this group may lead to more significant cognitive dysfunction

Mediators of Interpersonal Psychotherapy for Depressed Adolescents On Outcomes in Latinos: The Role of Peer and Family Interpersonal Functioning

Peer and family interpersonal functioning were examined as mediators of the impact of Interpersonal Psychotherapy for Depressed Adolescents (IPT-A; Mufson, Dorta, Moreau, & Weissman, 2004) on depression and suicidal ideation among Latino youth. Only youth self-identifying as Latino (n = 50) were included in the analyses. The majority were female (86%) with a mean age of 14.58 (SD = 1.91). The current sample was drawn from the intent to treat sample of a clinical trial examining the effectiveness of IPT-A as compared with treatment as usual (TAU; Mufson, Dorta, Wickramaratne et al., 2004). Youth were randomly assigned to receive IPT-A or TAU delivered by school-based mental health clinicians. Assessments, completed at baseline and at Weeks 4, 8, and 12 (or at early termination), included self-report measures of depression and interpersonal functioning as well as clinician-Administered measures of depression. Multilevel modeling indicated that IPT-A led to greater improvement in interpersonal functioning with family and peers. Improved family and peer interpersonal functioning emerged as significant partial mediators of the relationship between IPT-A and depression. Only improved family interpersonal functioning emerged as a significant partial mediator of the relationship between IPT-A and suicidal ideation. However, this indirect effect was small, suggesting that most of the benefit of IPT-A for suicidal ideation appears to proceed through a pathway other than family interpersonal functioning. These results suggest that the impact of IPT-A on depressive symptoms is partially mediated by family and peer interpersonal functioning and contributes to our understanding of the mechanisms of IPT-A

Hypersomnia subtypes, sleep and relapse in bipolar disorder.

BACKGROUND: Though poorly defined, hypersomnia is associated with negative health outcomes and new-onset and recurrence of psychiatric illness. Lack of definition impedes generalizability across studies. The present research clarifies hypersomnia diagnoses in bipolar disorder by exploring possible subgroups and their relationship to prospective sleep data and relapse into mood episodes. METHOD: A community sample of 159 adults (aged 18-70 years) with bipolar spectrum diagnoses, euthymic at study entry, was included. Self-report inventories and clinician-administered interviews determined features of hypersomnia. Participants completed sleep diaries and wore wrist actigraphs at home to obtain prospective sleep data. Approximately 7 months later, psychiatric status was reassessed. Factor analysis and latent profile analysis explored empirical groupings within hypersomnia diagnoses. RESULTS: Factor analyses confirmed two separate subtypes of hypersomnia (long sleep and excessive sleepiness) that were uncorrelated. Latent profile analyses suggested a four-class solution, with long sleep and excessive sleepiness again representing two separate classes. Prospective sleep data suggested that the sleep of long sleepers is characterized by a long time in bed, not long sleep duration. Longitudinal assessment suggested that excessive sleepiness at baseline predicted mania/hypomania relapse. CONCLUSIONS: This study is the largest of hypersomnia to include objective sleep measurement, and refines our understanding of classification, characterization and associated morbidity. Hypersomnia appears to be comprised of two separate subgroups: long sleep and excessive sleepiness. Long sleep is characterized primarily by long bedrest duration. Excessive sleepiness is not associated with longer sleep or bedrest, but predicts relapse to mania/hypomania. Understanding these entities has important research and treatment implications

PASI: A novel pathway method to identify delicate group effects

Pathway analysis is a common approach in diverse biomedical studies, yet the currently-available pathway tools do not typically support the increasingly popular personalized analyses. Another weakness of the currently-available pathway methods is their inability to handle challenging data with only modest group-based effects compared to natural individual variation. In an effort to address these issues, this study presents a novel pathway method PASI (Pathway Analysis for Sample-level Information) and demonstrates its performance on complex diseases with different levels of group-based differences in gene expression. PASI is freely available as an R package