SAGE 3: A visible wavelength limb sounder

A brief description is presented for the SAGE 3 (Stratospheric Aerosol and Gas Experiment 3) instrument that has been selected to fly onboard the National Polar Platform 1 (NPOP 1) for the Earth Observational System (Eos) in 1996. The SAGE 3 instrument will perform earth limb sounding with the solar occultation technique measuring the ultraviolet (UV), the visible, and the near infrared (IR) wavelength solar radiation. The instrument will produce atmospheric data for the vertical distribution of aerosol, ozone, nitrogen dioxide, water vapor, and oxygen. The details of the instrument design, data flow, and processing requirements are discussed

The power of cross-functional teams in driving total quality

Garrett Canada, a Division of Allied-Signal Aerospace Canada, has been a member of the Canadian aerospace industry for 40 years. Although Garrett Canada has always been a profitable division with a solid market share, the changing and turbulent business environment and globalization of the aerospace industry has created new demands and challenges. The marketplace is demanding faster introduction of new products, as well as shorter leadtimes for repairs and spares. It was recognized that reducing cycle times for new products and for ongoing production would not only satisfy our customers, it would also enhance our business performance through reduced inventories, lower past due, and more responsiveness to change. It was evident that drastic function changes were required if we were to maintain our position as a premier aerospace supplier. The challenge was to convert a stable, somewhat slow-paced work environment with strong functional boundaries into a boundaryless world class team functioning in a total quality environment and focused on customer satisfaction. Complete and uncompromised customer satisfaction has become our driving force, with Total Quality being our engine to continuously improve our processes and increase our speed. The way in which this transition has been brought about is the subject of this presentation

Hydrogeologic assessment of in situ natural attenuation in a controlled field experiment

An experiment to investigate the natural attenuation of three volatile organic compounds, toluene, carbon tetrachloride, and tetrachloroethene (∼1–10 mg L−1) was performed in a 3 m deep, sandy aquifer isolated within a 24 m long, 2 m wide, three-sided sheet pile alleyway (hereafter referred to as the gate). A constant flow was maintained in the test volume by pumping a well at the closed end of the gate at 130 mL min−1. The test compounds were introduced to the aquifer using diffusive emitters installed inside 25 cm diameter wells located at the open end of the gate. Monitoring was performed by sampling along six multilevel fences (consisting of 12 sampling points each) ranging in distance from 1 to 22 m from the source wells. A bromide tracer experiment established that there were no significant hydraulic leaks, nor was there any continuous channeling through the gate. Degradation of the test compounds was assessed by mass balance calculations between fences located 1 and 7 m from the source, and the results were compared with degradation rate estimates from snapshot analyses and the analysis of fluxes. There was reasonably good agreement between rates estimated by these different methods. Toluene degraded with a half-life of 58–62 days, carbon tetrachloride degraded with a half-life of ∼11–13 days, and tetrachloroethene degraded too slowly for a reliable estimate of rate to be made. Transformation products identified in the gate included acetate, possibly from toluene degradation, chloroform, trichloroethene, and cis-1,2, dichloroethene. The latter two compounds only appeared in trace quantities and could not be assessed for continuing degradation. However, chloroform degradation was assessed with the snapshot data and using the flux estimates and was found to degrade with a half-life in the range of 10–34 days. No additional chlorinated methanes were detected in the gate, suggesting that the carbon tetrachloride was completely dechlorinated by natural processes within 10 m of the source wells. This experiment demonstrated that degradation of chlorinated solvents occurs naturally at the Borden site but that the ethenes are more resistant to biodegradation than the methanes. In addition, the flux calculations were found to be the most robust in terms of estimating degradation rates.Financial support for this research was provided by the Advanced Alternative Technology Demonstration Facility, funded by the Department of Defense and administered by Rice University. Additional support was provided by the NSERC/Motorolla/ETI Industrial Research Chair in Groundwater Remediation and the Solvents in Groundwater Consortium, University of Waterloo. T. Anderson of the University of Massachusetts assisted with hydrogen measurements, while Susan Froud and Dennis Katic assisted with all other aspects of the fieldwork and participated in discussions of the data. Mike Brown is acknowledged for his contribution to the installation of the gate, and Stephanie Fiorenza is acknowledged for her comments and assistance liaising with AATDF

SAM-2 ground-truth plan: Correlative measurements for the Stratospheric Aerosol Measurement-2 (SAM 2) sensor on the Nimbus G satellite

The SAM-2 will fly aboard the Nimbus-G satellite for launch in the fall of 1978 and measure stratospheric vertical profiles of aerosol extinction in high latitude bands. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. The SAM-2 expected instrument performance and data inversion results are presented. Various atmospheric models representative of polar stratospheric aerosols are used in the SAM-2 and correlative sensor analyses

Placental Structure in Preterm Birth Among HIV-Positive Versus HIV-Negative Women in Kenya.

BackgroundPreterm birth (PTB) is a major cause of infant morbidity and mortality in developing countries. Recent data suggest that in addition to Human Immunodeficiency Virus (HIV) infection, use of antiretroviral therapy (ART) increases the risk of PTB. As the mechanisms remain unexplored, we conducted this study to determine whether HIV and ART were associated with placental changes that could contribute to PTB.SettingWe collected and evaluated placentas from 38 HIV-positive women on ART and 43 HIV-negative women who had preterm deliveries in Nairobi, Kenya.MethodsAnatomical features of the placentas were examined at gross and microscopic levels. Cases were matched for gestational age and compared by the investigators who were blinded to maternal HIV serostatus.ResultsAmong preterm placentas, HIV infection was significantly associated with thrombosis (P = 0.001), infarction (P = 0.032), anomalies in cord insertion (P = 0.02), gross evidence of membrane infection (P = 0.043), and reduced placental thickness (P = 0.010). Overall, preterm placentas in both groups were associated with immature villi, syncytial knotting, villitis, and deciduitis. Features of HIV-positive versus HIV-negative placentas included significant fibrinoid deposition with villus degeneration, syncytiotrophoblast delamination, red blood cell adhesion, hypervascularity, and reduction in both surface area and perimeter of the terminal villi.ConclusionsThese results imply that HIV infection and/or ART are associated with morphological changes in preterm placentas that contribute to delivery before 37 weeks. Hypervascularity suggests that the observed pathologies may be attributable, in part, to hypoxia. Further research to explore potential mechanisms will help elucidate the pathways that are involved perhaps pointing to interventions for decreasing the risk of prematurity among HIV-positive women

Planet Four: Terrains - Discovery of Araneiforms Outside of the South Polar Layered Deposits

We present the results of a systematic mapping of seasonally sculpted terrains on the South Polar region of Mars with the Planet Four: Terrains (P4T) online citizen science project. P4T enlists members of the general public to visually identify features in the publicly released Mars Reconnaissance Orbiter CTX images. In particular, P4T volunteers are asked to identify: 1) araneiforms (including features with a central pit and radiating channels known as 'spiders'); 2) erosional depressions, troughs, mesas, ridges, and quasi-circular pits characteristic of the South Polar Residual Cap (SPRC) which we collectively refer to as 'Swiss cheese terrain', and 3) craters. In this work we present the distributions of our high confidence classic spider araneiforms and Swiss cheese terrain identifications. We find no locations within our high confidence spider sample that also have confident Swiss cheese terrain identifications. Previously spiders were reported as being confined to the South Polar Layered Deposits (SPLD). Our work has provided the first identification of spiders at locations outside of the SPLD, confirmed with high resolution HiRISE imaging. We find araneiforms on the Amazonian and Hesperian polar units and the Early Noachian highland units, with 75% of the identified araneiform locations in our high confidence sample residing on the SPLD. With our current coverage, we cannot confirm whether these are the only geologic units conducive to araneiform formation on the Martian South Polar region. Our results are consistent with the current CO2 jet formation scenario with the process exploiting weaknesses in the surface below the seasonal CO2 ice sheet to carve araneiform channels into the regolith over many seasons. These new regions serve as additional probes of the conditions required for channel creation in the CO2 jet process. (Abridged)Comment: accepted to Icarus - Supplemental data files are available at https://www.zooniverse.org/projects/mschwamb/planet-four-terrains/about/results - Icarus print version available at http://www.sciencedirect.com/science/article/pii/S001910351730055

Development of a generic activities model of command and control

This paper reports on five different models of command and control. Four different models are reviewed: a process model, a contextual control model, a decision ladder model and a functional model. Further to this, command and control activities are analysed in three distinct domains: armed forces, emergency services and civilian services. From this analysis, taxonomies of command and control activities are developed that give rise to an activities model of command and control. This model will be used to guide further research into technological support of command and control activities

The Hubble Space Telescope Treasury Program on the Orion Nebula Cluster

The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2) and the Near Infrared Camera and Multi Object Spectrograph (NICMOS) instruments in 11 filters ranging from the U-band to the H-band equivalent of HST. The program has been intended to perform the definitive study of the stellar component of the ONC at visible wavelengths, addressing key questions like the cluster IMF, age spread, mass accretion, binarity and cirumstellar disk evolution. The scanning pattern allowed to cover a contiguous field of approximately 600 square arcminutes with both ACS and WFPC2, with a typical exposure time of approximately 11 minutes per ACS filter, corresponding to a point source depth AB(F435W) = 25.8 and AB(F775W)=25.2 with 0.2 magnitudes of photometric error. We describe the observations, data reduction and data products, including images, source catalogs and tools for quick look preview. In particular, we provide ACS photometry for 3399 stars, most of them detected at multiple epochs, WFPC2 photometry for 1643 stars, 1021 of them detected in the U-band, and NICMOS JH photometry for 2116 stars. We summarize the early science results that have been presented in a number of papers. The final set of images and the photometric catalogs are publicly available through the archive as High Level Science Products at the STScI Multimission Archive hosted by the Space Telescope Science Institute.Comment: Accepted for publication on the Astrophysical Journal Supplement Series, March 27, 201

An inverted-sandwich diuranium μ-η5:η5-cyclo-P5 complex supported by U-P5 δ-bonding

Reaction of [U(TrenTIPS)] [1, TrenTIPS=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(TrenTIPS)}2(μ-η5:η5-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals