Generalized Dissociating Gas Flow

A generalized approach to the one-dimensional flow of a dissociated gas is presented. The flow is characterized by the flow parameters F, G, H, and I, and the degree of dissociation, which are defined. The equation of state and the equations for the dynamic and thermodynamic properties of the gas are presented for the dissociating gas. Equations are presented which give the aerothermodynamic flow properties as a function of the degree of dissociation, the frozen flow Mach number MF, and the initial values of G, H, and I for any arbitrary given flight condition. These equations are solved for the limiting subsonic and hypersonic solutions for the flow variables as the frozen flow Mach number MF tends towards zero and infinity, respectively. Several aspects of the physical significance of these results are discussed from the point of view of atmospheric planetary entry of an aerospace vehicle. The generalized nondimensional flow function F is defined in terms of the flow parameters G, H, and I , and is also given as a function of MF, H, and a, in general. This functional relationship is displayed in graphical form which is useful for determining various aspects of the resulting flow, and providing further insight into the flow process under consideration. Specifically, several flow regimes are delineated

A System of Computer Programs to Calculate Aerodynamic Characteristics for Missiles, Reentry Vehicles, and Spacecraft at Angles of Attack

At the Fifth Space Congress, a method was [ presented for predicting the inviscid gas properties surrounding blunt nosed aerospace j vehicles in supersonic or hypersonic flight, at zero angle of attack {Reference l)o Two computer programs used in combination were utilized.) :At that time it was indicated (References 1 and 2) that this capability was to be extended, using j a new unique system of eleven different computer j programs, in order to provide for the calculation; of gaseous properties and aerodynamic characteristics for vehicles flying at angles of attack. At angles of attack, the problem of predicting the gas properties and aerodynamic characteristics is an order of magnitude more difficult due to the fact that the flow field is threedimensional. That is, the flow properties vary in all three directions: as a function of body axial station, location around the body (at a given station), and distance away from the body. ;The newer set of programs also provides the capability of handling vehicles with sharp as well as blunt noses, and includes the capability of predicting the viscous flow boundary layer properties on the vehicle surface. Most of the programs were originally developed under U.S. Air Force and Army Contracts by General Applied Science Laboratories. The programs were converted to operate on the Control Data Model CDC 6^-00 digital computer used at Martin Marietta I Corporation\u27s Orlando Division. Over the past year, many modifications have been made to the system of computer programs to increase the efficiency of utilization (by simplifying the j inputs required, etc.), reduce the computer run I time (cost of operation), and to increase its : capability (calculate aerodynamic characteristics etc.)

Effects of surgical targeting in laser interstitial thermal therapy for mesial temporal lobe epilepsy: A multicenter study of 234 patients

OBJECTIVE: Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) has reported seizure freedom rates between 36% and 78% with at least 1 year of follow-up. Unfortunately, the lack of robust methods capable of incorporating the inherent variability of patient anatomy, the variability of the ablated volumes, and clinical outcomes have limited three-dimensional quantitative analysis of surgical targeting and its impact on seizure outcomes. We therefore aimed to leverage a novel image-based methodology for normalizing surgical therapies across a large multicenter cohort to quantify the effects of surgical targeting on seizure outcomes in LITT for mTLE. METHODS: This multicenter, retrospective cohort study included 234 patients from 11 centers who underwent LITT for mTLE. To investigate therapy location, all ablation cavities were manually traced on postoperative magnetic resonance imaging (MRI), which were subsequently nonlinearly normalized to a common atlas space. The association of clinical variables and ablation location to seizure outcome was calculated using multivariate regression and Bayesian models, respectively. RESULTS: Ablations including more anterior, medial, and inferior temporal lobe structures, which involved greater amygdalar volume, were more likely to be associated with Engel class I outcomes. At both 1 and 2 years after LITT, 58.0% achieved Engel I outcomes. A history of bilateral tonic-clonic seizures decreased chances of Engel I outcome. Radiographic hippocampal sclerosis was not associated with seizure outcome. SIGNIFICANCE: LITT is a viable treatment for mTLE in patients who have been properly evaluated at a comprehensive epilepsy center. Consideration of surgical factors is imperative to the complete assessment of LITT. Based on our model, ablations must prioritize the amygdala and also include the hippocampal head, parahippocampal gyrus, and rhinal cortices to maximize chances of seizure freedom. Extending the ablation posteriorly has diminishing returns. Further work is necessary to refine this analysis and define the minimal zone of ablation necessary for seizure control

Charting the road forward in psychiatric neurosurgery: proceedings of the 2016 American Society for Stereotactic and Functional Neurosurgery workshop on neuromodulation for psychiatric disorders

OBJECTIVE: Refractory psychiatric disease is a major cause of morbidity and mortality worldwide, and there is a great need for new treatments. In the last decade, investigators piloted novel deep brain stimulation (DBS)-based therapies for depression and obsessive-compulsive disorder (OCD). Results from recent pivotal trials of these therapies, however, did not demonstrate the degree of efficacy expected from previous smaller trials. To discuss next steps, neurosurgeons, neurologists, psychiatrists and representatives from industry convened a workshop sponsored by the American Society for Stereotactic and Functional Neurosurgery in Chicago, Illinois, in June of 2016. DESIGN: Here we summarise the proceedings of the workshop. Participants discussed a number of issues of importance to the community. First, we discussed how to interpret results from the recent pivotal trials of DBS for OCD and depression. We then reviewed what can be learnt from lesions and closed-loop neurostimulation. Subsequently, representatives from the National Institutes of Health, the Food and Drug Administration and industry discussed their views on neuromodulation for psychiatric disorders. In particular, these third parties discussed their criteria for moving forward with new trials. Finally, we discussed the best way of confirming safety and efficacy of these therapies, including registries and clinical trial design. We close by discussing next steps in the journey to new neuromodulatory therapies for these devastating illnesses. CONCLUSION: Interest and motivation remain strong for deep brain stimulation for psychiatric disease. Progress will require coordinated efforts by all stakeholders

Multiorganizational consensus to define guiding principles for perioperative pain management in patients with chronic pain, preoperative opioid tolerance, or substance use disorder

Significant knowledge gaps exist in the perioperative pain management of patients with a history of chronic pain, substance use disorder, and/or opioid tolerance as highlighted in the US Health and Human Services Pain Management Best Practices Inter-Agency Task Force 2019 report. The report emphasized the challenges of caring for these populations and the need for multidisciplinary care and a comprehensive approach. Such care requires stakeholder alignment across multiple specialties and care settings. With the intention of codifying this alignment into a reliable and efficient processes, a consortium of 15 professional healthcare societies was convened in a year-long modified Delphi consensus process and summit. This process produced seven guiding principles for the perioperative care of patients with chronic pain, substance use disorder, and/or preoperative opioid tolerance. These principles provide a framework and direction for future improvement in the optimization and care of \u27complex\u27 patients as they undergo surgical procedures