Identification of Vehicle Health Assurance Related Trends

Trend analysis in aviation as related to vehicle health management (VHM) was performed by reviewing the most current statistical and prognostics data available from the National Transportation Safety Board (NTSB) accident, the Federal Aviation Administration (FAA) incident, and the NASA Aviation Safety Reporting System (ASRS) incident datasets. In addition, future directions in aviation technology related to VHM research areas were assessed through the Commercial Aviation Safety Team (CAST) Safety Enhancements Reserved for Future Implementations (SERFIs), the National Transportation Safety Board (NTSB) Most-Wanted List and recent open safety recommendations, the National Research Council (NRC) Decadal Survey of Civil Aeronautics, and the Future Aviation Safety Team (FAST) areas of change. Future research direction in the VHM research areas is evidently strong as seen from recent research solicitations from the Naval Air Systems Command (NAVAIR), and VHM-related technologies actively being developed by aviation industry leaders, including GE, Boeing, Airbus, and UTC Aerospace Systems. Given the highly complex VHM systems, modifications can be made in the future so that the Vehicle Systems Safety Technology Project (VSST) technical challenges address inadequate maintenance crew's trainings and skills, and the certification methods of such systems as recommended by the NTSB, NRC, and FAST areas of change

Rapid X-ray Variability of Seyfert 1 Galaxies

The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive black hole fed from an accretion disc. However, since EXOSAT there has been little opportunity to advance our understanding of the most rapid X-ray variability. Observations with XMM-Newton have changed this. We discuss some recent results obtained from XMM-Newton observations of Seyfert 1 galaxies. Particular attention will be given to the remarkable similarity found between the timing properties of Seyferts and black hole X-ray binaries, including the power spectrum and the cross spectrum (time delays and coherence), and their implications for the physical processes at work in Seyferts.Comment: To appear in From X-ray Binaries to Quasars: Black Hole Accretion on All Mass Scales, ed. T. J. Maccarone, R. P. Fender, and L. C. Ho (Dordrecht: Kluwer

Aviation Trends Related to Atmospheric Environment Safety Technologies Project Technical Challenges

Current and future aviation safety trends related to the National Aeronautics and Space Administration's Atmospheric Environment Safety Technologies Project's three technical challenges (engine icing characterization and simulation capability; airframe icing simulation and engineering tool capability; and atmospheric hazard sensing and mitigation technology capability) were assessed by examining the National Transportation Safety Board (NTSB) accident database (1989 to 2008), incidents from the Federal Aviation Administration (FAA) accident/incident database (1989 to 2006), and literature from various industry and government sources. The accident and incident data were examined for events involving fixed-wing airplanes operating under Federal Aviation Regulation (FAR) Parts 121, 135, and 91 for atmospheric conditions related to airframe icing, ice-crystal engine icing, turbulence, clear air turbulence, wake vortex, lightning, and low visibility (fog, low ceiling, clouds, precipitation, and low lighting). Five future aviation safety risk areas associated with the three AEST technical challenges were identified after an exhaustive survey of a variety of sources and include: approach and landing accident reduction, icing/ice detection, loss of control in flight, super density operations, and runway safety

Spontaneous CP Violation at the Electroweak Scale

Utilizing results on the cosmology of anomalous discrete symmetries we show that models of spontaneous CP violation can in principle avoid the domain wall problem first pointed out by Zel'dovich, Kobzarev and Okun. A small but nonzero $\theta_{QCD}$ explicitly breaks CP and can lift the degeneracy of the two CP conjugate vacua through nonperturbative effects so that the domain walls become unstable, but survive to cosmologically interesting epochs. We explore the viability of spontaneous CP violation in the context of two Higgs models, and find that the invisible axion solution of the strong CP problem cannot be implemented without further extensions of the Higgs sector.Comment: 10 page

Hypercharge and the Cosmological Baryon Asymmetry

Stringent bounds on baryon and lepton number violating interactions have been derived from the requirement that such interactions, together with electroweak instantons, do not destroy a cosmological baryon asymmetry produced at an extremely high temperature in the big bang. While these bounds apply in specific models, we find that they are generically evaded. In particular, the only requirement for a theory to avoid these bounds is that it contain charged particles which, during a certain cosmological epoch, carry a non-zero hypercharge asymmetry. Hypercharge neutrality of the universe then dictates that the remaining particles must carry a compensating hypercharge density, which is necessarily shared amongst them so as to give a baryon asymmetry. Hence the generation of a hypercharge density in a sector of the theory forces the universe to have a baryon asymmetry.Comment: 12 pages plus 1 Postscript figure available upon request. LBL 3482

The X-ray variability of the Seyfert~1 galaxy MCG-6-30-15 from long ASCA and RXTE observations

We present an analysis of the long RXTE observation of the Seyfert~1 galaxy MCG-6-30-15, taken in July 1997. Our results show that the behaviour is complicated. We find clear evidence from colour ratios and direct spectral fitting that changes to the intrinsic photon index are taking place. Spectral hardening is evident during periods of diminished intensity; in particular, a general trend for harder spectra is seen in the period following the hardest RXTE flare. Flux-correlated studies further show that the 3-10 keV photon index steepens while that in the 10-20 keV band, flattens with flux. The largest changes come from the spectral index below 10keV; however, changes in the intrinsic power law slope, and reflection both contribute in varying degrees to the overall spectral variability. We find that the iron line flux is consistent with being constant over large time intervals on the order of days (although the ASCA and RXTE spectra show that $F_{K\alpha}$ changes on shorter time intervals of order < 10ks), and equivalent width which anticorrelates with the continuum flux, and reflection fraction. Flux-correlated studies point at possible ionization signatures, while detailed spectral analysis of short time intervals surrounding flare events hint tentatively at observed spectral responses to the flare. We present a simple model for partial ionization where the bulk of the variability comes from within 6r_g. Temporal analysis further provides evidence for possible time (< 1000s) and phase (phi~0.6 rad) lags. Finally, we report an apparent break in the power density spectrum (~ 4-5 x 10^{-6}Hz) and a possible 33 hr period. Estimates for the mass of the black hole in MCG-6-30-15 are discussed in the context of spectral and temporal findings.Comment: 19 pages, 38 figures total (19 figure captions), accepted for publication in MNRAS July 200

X-ray variability in a complete sample of Soft X-ray selected AGN

We present ROSAT All-Sky Survey and ROSAT pointed observations (PSPC and HRI) of a complete sample of 113 bright soft X-ray AGN selected from the ROSAT Bright Source Catalog. We compare these observations in order to search for extreme cases of flux and spectral X-ray variability - X-ray transient AGN. Three definite transients and one transient candidate are found. The other sources show amplitude variations typically by factors of 2-3 on timescales of years. We found that the variability strength on timescales of days is a function of the steepness of the X-ray spectrum: steeper X-ray objects show stronger variability than flat X-ray spectrum sources. We also present new HRI measurements of our extreme X-ray transients IC 3599 and WPVS007. We discuss possible models to explain the X-ray transience and the variabilities observed in the non-transient sources.Comment: 17 pages (including 7 Figures), accepted for in A&A (main journal), also available at http://www.xray.mpe.mpg.de/~dgrupe/research/refereed.htm

Prediagnostic Serum Concentrations of Organochlorine Compounds and Risk of Testicular Germ Cell Tumors

BACKGROUND: Recent findings suggest that exposure to organochlorine (OC) compounds, chlordanes and p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) in particular, may increase the risk of developing testicular germ cell tumors (TGCTs). OBJECTIVE: To further investigate this question, we conducted a nested case-control study of TGCTs within the Norwegian Janus Serum Bank cohort. METHODS: The study was conducted among individuals with serum collected between 1972 and 1978. TGCT cases diagnosed through 1999 (n = 49; 27-62 years of age at diagnosis) were identified through linkage to the Norwegian Cancer Registry. Controls (n =51) were matched to cases on region, blood draw year, and age at blood draw. Measurements of 11 OC insecticide compounds and 34 polychlorinated biphenyl (PCB) congeners were performed using gas chromatography/high-resolution mass spectrometry. Case-control comparisons of lipid-adjusted analyte concentrations were performed using the Wilcoxon signed-rank test. Odds ratios (ORs) and 95% confidence intervals (CIs) for tertiles of analyte concentration were calculated using conditional logistic regression. RESULTS: TGCT cases had elevated concentrations of p,p′-DDE (tertile 3 vs. tertile 1 OR (ORT3) 2.2; 95% CI, 0.7-6.5; p Wilcoxon = 0.07), oxychlordane (ORT3 3.2; 95% CI, 0.6-16.8; pWilcoxon = 0.05), trans-nonachlor (ORT3 2.6; 95% CI, 0.7-8.9; pWilcoxon = 0.07), and total chlordanes (OR T3 2.0; 95% CI, 0.6-7.2; pWilcoxon = 0.048) compared with controls, although no ORs were statistically significant. Seminoma cases had significantly lower concentrations of PCB congeners 44, 49, and 52 and significantly higher concentrations of PCBs 99, 138, 153, 167, 183, and 195. CONCLUSIONS: Our study provides additional but qualified evidence supporting an association between exposures to p,p′-DDE and chlordane compounds, and possibly some PCB congeners, and TGCT risk

Stable isotopic composition of upper oceanic crust formed at a fast spreading ridge, ODP Site 801

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94808/1/ggge303.pd