Methodology for back-contamination risk assessment for a Mars sample return mission

The risk of back-contamination from Mars Surface Sample Return (MSSR) missions is assessed. The methodology is designed to provide an assessment of the probability that a given mission design and strategy will result in accidental release of Martian organisms acquired as a result of MSSR. This is accomplished through the construction of risk models describing the mission risk elements and their impact on back-contamination probability. A conceptual framework is presented for using the risk model to evaluate mission design decisions that require a trade-off between science and planetary protection considerations

Autonomous power expert system

The goal of the Autonomous Power System (APS) program is to develop and apply intelligent problem solving and control technologies to the Space Station Freedom Electrical Power Systems (SSF/EPS). The objectives of the program are to establish artificial intelligence/expert system technology paths, to create knowledge based tools with advanced human-operator interfaces, and to integrate and interface knowledge-based and conventional control schemes. This program is being developed at the NASA-Lewis. The APS Brassboard represents a subset of a 20 KHz Space Station Power Management And Distribution (PMAD) testbed. A distributed control scheme is used to manage multiple levels of computers and switchgear. The brassboard is comprised of a set of intelligent switchgear used to effectively switch power from the sources to the loads. The Autonomous Power Expert System (APEX) portion of the APS program integrates a knowledge based fault diagnostic system, a power resource scheduler, and an interface to the APS Brassboard. The system includes knowledge bases for system diagnostics, fault detection and isolation, and recommended actions. The scheduler autonomously assigns start times to the attached loads based on temporal and power constraints. The scheduler is able to work in a near real time environment for both scheduling and dynamic replanning

Study of storm time fluxes of heavy ions

Ion composition data sets from Lockheed instruments on a variety of spacecraft were used in combination with each other and with data from other instruments to address a variety of problems regarding plasma sources, energization and transport within the magnetosphere. The availability of data from several differing orbits has given a highly flexible approach to attacking the continually evolving questions of magnetospheric physics. This approach is very successful and should be continued in the future

Reliability of the modified Rankin Scale: a systematic review

<p><b>Background and Purpose:</b> A perceived weakness of the modified Rankin Scale is potential for interobserver variability. We undertook a systematic review of modified Rankin Scale reliability studies.</p> <p><b>Methods:</b> Two researchers independently reviewed the literature. Crossdisciplinary electronic databases were interrogated using the following key words: Stroke*; Cerebrovasc*; Modified Rankin*; Rankin Scale*; Oxford Handicap*; Observer variation*. Data were extracted according to prespecified criteria with decisions on inclusion by consensus.</p> <p><b>Results:</b> From 3461 titles, 10 studies (587 patients) were included. Reliability of modified Rankin Scale varied from weighted κ=0.95 to κ=0.25. Overall reliability of mRS was κ=0.46; weighted κ=0.90 (traditional modified Rankin Scale) and κ=0.62; weighted κ=0.87 (structured interview).</p> <p><b>Conclusion:</b> There remains uncertainty regarding modified Rankin Scale reliability. Interobserver studies closest in design to large-scale clinical trials demonstrate potentially significant interobserver variability.</p&gt

Exploring the reliability of the modified Rankin Scale

<p><b>Background and Purpose:</b> The modified Rankin Scale (mRS) is the most prevalent outcome measure in stroke trials. Use of the mRS may be hampered by variability in grading. Previous estimates of the properties of the mRS have used diverse methodologies and may not apply to contemporary trial populations. We used a mock clinical trial design to explore inter- and intraobserver variability of the mRS.</p> <p><b>Methods:</b> Consenting patients with stroke attending for outpatient review had the mRS performed by 2 independent assessors with pairs of assessors selected from a team of 3 research nurses and 4 stroke physicians. Before formal assessment, interviewers estimated disability based only on initial patient observation. Each patient was then randomized to undergo the mRS using standard assessment or a prespecified structured interview. The second interviewer in the pair reassessed the patient using the same method blinded to the colleague’s score. For each patient assessed, one rater was randomly assigned to video record their interview. After 3 months, this interviewer reviewed and regraded their original video assessment.</p> <p><b>Results:</b> Across 100 paired assessments, interobserver agreement was moderate (k=0.57). Intraobserver variability was good (k=0.72) but less than would be expected from previous literature. Forty-nine assessments were performed using the structured interview approach with no significant difference between structured and standard mRS. Researchers were unable to reliably predict mRS from initial limited patient assessment (k=0.16).</p> <p><b>Conclusions:</b> Despite availability of training and structured interview, there remains substantial interobserver variability in mRS grades awarded even by experienced researchers. Additional methods to improve mRS reliability are required.</p&gt

Variability in modified rankin scoring across a large cohort of observers

<br>Background and Purpose— The modified Rankin scale (mRS) is the most commonly used outcome measure in stroke trials. However, substantial interobserver variability in mRS scoring has been reported. These studies likely underestimate the variability present in multicenter clinical trials, because exploratory work has only been undertaken in single centers by a few observers, all of similar training. We examined mRS variability across a large cohort of international observers using data from a video training resource.</br> <br>Methods— The mRS training package includes a series of “real-life” patient interviews for grading. Training data were collected centrally and analyzed for variability using kappa statistics. We examined variability against a standard of “correct” mRS grades; examined variability by country; and for UK assessors, examined variability by center and by professional background of the observer.</br> <br>Results— To date, 2942 assessments from 30 countries have been submitted. Overall reliability for mRS grading has been moderate to good with substantial heterogeneity across countries. Native English language has had little effect on reliability. Within the United Kingdom, there was no significant variation by profession.</br> <br>Conclusion— Our results confirm interobserver variability in mRS assessment. The heterogeneity across countries is intriguing because it appears not to be related solely to language. These data highlight the need for novel strategies to improve reliability.</br&gt

Astrophysical Effects of Scalar Dark Matter Miniclusters

We model the formation, evolution and astrophysical effects of dark compact Scalar Miniclusters (``ScaMs''). These objects arise when a scalar field, with an axion-like or Higgs-like potential, undergoes a second order phase transition below the QCD scale. Such a scalar field may couple too weakly to the standard model to be detectable directly through particle interactions, but may still be detectable by gravitational effects, such as lensing and baryon accretion by large, gravitationally bound miniclusters. The masses of these objects are shown to be constrained by the Ly$\alpha$ power spectrum to be less than $\sim 10^4 M_\odot$, but they may be as light as classical axion miniclusters, of the order of $10^{-12} M_\odot$. We simulate the formation and nonlinear gravitational collapse of these objects around matter-radiation equality using an N-body code, estimate their gravitational lensing properties, and assess the feasibility of studying them using current and future lensing experiments. Future MACHO-type variability surveys of many background sources can reveal either high-amplification, strong lensing events, or measure density profiles directly via weak-lensing variability, depending on ScaM parameters and survey depth. However, ScaMs, due to their low internal densities, are unlikely to be responsible for apparent MACHO events already detected in the Galactic halo. A simple estimate is made of parameters that would give rise to early structure formation; in principle, early stellar collapse could be triggered by ScaMs as early as recombination, and significantly affect cosmic reionization.Comment: 13 pages, 12 figures. Replaced to reflect published versio