Capturing, using, and managing quality assurance knowledge for shuttle post-MECO flight design

Ascent initialization values used by the Shuttle's onboard computer for nominal and abort mission scenarios are verified by a six degrees of freedom computer simulation. The procedure that the Ascent Post Main Engine Cutoff (Post-MECO) group uses to perform quality assurance (QA) of the simulation is time consuming. Also, the QA data, checklists and associated rationale, though known by the group members, is not sufficiently documented, hindering transfer of knowledge and problem resolution. A new QA procedure which retains the current high level of integrity while reducing the time required to perform QA is needed to support the increasing Shuttle flight rate. Documenting the knowledge is also needed to increase its availability for training and problem resolution. To meet these needs, a knowledge capture process, embedded into the group activities, was initiated to verify the existing QA checks, define new ones, and document all rationale. The resulting checks were automated in a conventional software program to achieve the desired standardization, integrity, and time reduction. A prototype electronic knowledge base was developed with Macintosh's HyperCard to serve as a knowledge capture tool and data storage

Planar laser-induced fluorescence imaging of Si and SiO during pulsed laser ablation of Si

Planar laser induced fluorescence has been used to acquire time sequence images of ground-state, neutral Si and SiO during laser ablation of an Si target in vacuum and in the presence of a background gas at a fluence of 3-4 J/cm^2. The SiO images, taken in air, strongly suggest that the observed SiO is created through reaction of silicon with oxygen at the contact front as the plume expands

Sites of Biosynthesis of Outer and Inner Membrane Proteins of Neurospora crassa Mitochondria

Outer and inner membranes of Neurospora crassa mitochondria were separated by the combined swelling, shrinking, sonication procedure. Membranes were characterized by electron microscopy and by marker enzyme activities. A red carotenoid pigment was found to be concentrated in the outer membrane. The inner mitochondrial membrane was resolved into about 20 protein bands on polyacrylamide gel electrophoresis, whereas the outer membrane shows essentially one single protein band. Only negligible incorporation of radioactive amino acids occurs into outer membrane when isolated mitochondria are synthesizing polypeptide chains. In agreement with this observation labeling of outer membrane protein is almost entirely blocked, when whole Neurospora cells are incubated with radioactive amino acids in the presence of cycloheximide, an inhibitor of cytoplasmic protein synthesis. Finally, the essential electrophoretic protein band from outer membrane does not become labeled when mitochondria are incubated with radioactive amino acids either in vitro or in vivo in the presence of cycloheximide. It is concluded that the vast majority, if not all, of the outer membrane protein is synthesized by the cytoplasmic system and that polypeptide chains formed by the mitochondrial ribosomes are integrated into the inner mitochondrial membrane

The orbit structure of Dynkin curves

Let G be a simple algebraic group over an algebraically closed field k; assume that Char k is zero or good for G. Let \cB be the variety of Borel subgroups of G and let e in Lie G be nilpotent. There is a natural action of the centralizer C_G(e) of e in G on the Springer fibre \cB_e = {B' in \cB | e in Lie B'} associated to e. In this paper we consider the case, where e lies in the subregular nilpotent orbit; in this case \cB_e is a Dynkin curve. We give a complete description of the C_G(e)-orbits in \cB_e. In particular, we classify the irreducible components of \cB_e on which C_G(e) acts with finitely many orbits. In an application we obtain a classification of all subregular orbital varieties admitting a finite number of B-orbits for B a fixed Borel subgroup of G.Comment: 12 pages, to appear in Math

Theory for the Ultrafast Structural Response of optically excited small clusters: Time-dependence of the Ionization Potential

Combining an electronic theory with molecular dynamics simulations we present results for the ultrafast structural changes in small clusters. We determine the time scale for the change from the linear to a triangular structure after the photodetachment process Ag$_3^- \rightarrow {\rm Ag}_3$. We show that the time-dependent change of the ionization potential reflects in detail the internal degrees of freedom, in particular coherent and incoherent motion, and that it is sensitive to the initial temperature. We compare with experiment and point out the general significance of our results.Comment: 10 pages, Revtex, 3 postscript figure

Distracted Driver Behaviors and Distracting Conditions Among Adolescent Drivers: Findings From a Naturalistic Driving Study

AbstractPurposeThe proliferation of new communication technologies and capabilities has prompted concern about driving safety. This concern is particularly acute for inexperienced adolescent drivers. In addition to being early adopters of technology, many adolescents have not achieved the degree of automaticity in driving that characterizes experienced adults. Consequently, distractions may be more problematic in this group. Yet little is known about the nature or prevalence of distracted driving behaviors or distracting conditions among adolescent drivers.MethodVehicles of 52 high-school age drivers (N = 38 beginners and N = 14 more experienced) were equipped for 6 months with unobtrusive event-triggered data recorders that obtain 20-second clips of video, audio, and vehicle kinematic information when triggered. A low recording trigger threshold was set to obtain a sample of essentially random driving segments along with those indicating rough driving behaviors.ResultsElectronic device use (6.7%) was the most common single type of distracted behavior, followed by adjusting vehicle controls (6.2%) and grooming (3.8%). Most distracted driver behaviors were less frequent when passengers were present. However, loud conversation and horseplay were quite common in the presence of multiple peer passengers. These conditions were associated with looking away from the road, the occurrence of serious events, and, to a lesser extent, rough driving (high g-force events).ConclusionsCommon assumptions about adolescent driver distraction are only partially borne out by in-vehicle measurement. The association of passengers with distraction appears more complex than previously realized. The relationship between distractions and serious events differed from the association with rough driving