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  • 1
    Publication Date: 2016-02-27
    Description: Anthropogenic CO 2 release is increasing the p CO 2 in the atmosphere and oceans and causing a decrease in the pH of the oceans. This decrease in pH, known as ocean acidification, can have substantial negative effects on marine life. In this study, we use wild-brooded larvae and larvae from females held in treatment pH for two brooding cycles over 2 years to detect carryover effects from oogenesis and embryogenesis. Ovigerous females were held at three pHs: ~8.1 (Ambient), 7.8, and 7.5. Exposure to acidified conditions at the larval stage alone had minimal effects on the larvae, possibly because larvae may be adapted to living in an environment with large pH swings. Exposure of Tanner crab larvae to low pH during the embryo phase had a more substantial effect on morphology, size, Ca/Mg content, and metabolic rate than exposure during the larval phase, and maternal exposure during the oogenesis phase increased the carryover effect. Although the larval phase itself is resilient to low pH, carryover effects are likely to have a negative effect on larvae in the wild. These results, combined with negative effects of high p CO 2 at other life history stages, indicate that high p CO 2 may have a negative effect on the Tanner crab populations and fisheries soon.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 2
    Publication Date: 2016-02-27
    Description: Demographic models of pre- and post-recruitment population dynamics were developed to account for the effects of ocean acidification on biological parameters that affect southern Tanner crab ( Chionoecetes bairdi ) larval hatching success and larval and juvenile survival. Projections of stock biomass based on these linked models were used to calculate biological and economic reference points on which fisheries management advice is based and thus provide fisheries managers with strategic advice on the likely long-term consequences of ocean acidification. The models utilized information for southern Tanner crab in the eastern Bering Sea. This information included the monitoring data on which conventional size-structured stock assessments are based, as well as the functional relationships that determine survival based on experiments that evaluated the consequences of ocean acidification over the next 100–200 years on crab larval hatching success, larval survival, and the survival of juvenile crab. The results highlighted that juvenile survival had the largest effect (~20% decrease over 75 years) on biological and economic reference points, while hatching success, particularly if density dependence occurs after hatching, and larval survival have smaller effects (〈10% decrease). Catch and profits would be expected to decrease by 〉50% in 20 years if natural mortality is affected by ocean acidification. Additional laboratory data on oocyte and embryo development leads to large changes in biological reference points depending on the timing of ocean acidification effects relative to natural mortality. The results highlight the need for experiments to evaluate the longer term physiological effects of ocean acidification on multiple life history stages and to measure indices that directly inform population dynamics models to evaluate future management scenarios.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 3
    Publication Date: 2016-02-27
    Description: Ocean acidification, a decrease in ocean pH due to absorption of anthropogenic atmospheric CO 2 , has variable effects on different species. To examine the effects of long-term exposure on Tanner crab ( Chionoecetes bairdi ) embryonic development, hatching success, and calcification, ovigerous females were reared in one of three treatments: ambient pH (~8.1), pH 7.8, and pH 7.5 for 2 years. Embryos and larvae in year 1 were from oocytes developed in the field and appear resilient to high p CO 2 . Embryos and larvae in year 2 were from oocytes developed under high p CO 2 conditions. Oocyte development appears sensitive to high p CO 2 , effects carryover and altered embryonic development, and reduced hatching success with on average 71% fewer viable larvae hatched in the pH 7.5 treatment than in the other treatments. Per cent calcium was reduced among females exposed to pH 7.5 waters, and their carapaces were noticeably more pliable than those in the other treatments. Softer carapaces may result in reduced defences against predators, and a reduction in the ability to feed on prey with hard parts such as shells. The results from this long-term study suggest that projected ocean pH levels within the next two centuries will likely have a pronounced impact on Tanner crab populations unless the crab are able to acclimatize or adapt to changing conditions.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 4
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    Unknown
    In:  CASI
    Publication Date: 2006-10-26
    Description: Explorer XIII telemetry design
    Keywords: COMMUNICATIONS
    Format: text
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  • 5
    Publication Date: 2019-06-27
    Description: A nondestructive method of applying and removing instrumentation on airfoils.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: application/pdf
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  • 6
    Publication Date: 2019-06-28
    Description: The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed and analysis of the Communication and Tracking hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter Communication and Tracking hardware. The IOA product for the Communication and Tracking consisted of 1,108 failure mode worksheets that resulted in 298 critical items being identified. Comparison was made to the NASA baseline which consists of 697 FMEAs and 239 CIL items. The comparison determined if there were any results which had been found by IOA but were not in the NASA baseline. This comparison produced agreement on all but 407 FMEAs which caused differences in 294 CIL items. Volume 1 contains the subsystem description, assessment results, ground rules and assumptions, and some of the IOA worksheets.
    Keywords: SPACE TRANSPORTATION
    Type: NASA-CR-185528-VOL-1 , NAS 1.26:185528-VOL-1 , REPT-1.0-WP-VA88005-10-VOL-1
    Format: application/pdf
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  • 7
    Publication Date: 2019-06-28
    Description: The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed and analysis of the Communication and Tracking hardware, generating draft failure modes and potential critical items. The IOA results were then compared to the NASA FMEA/CIL baseline. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter Communication and Tracking hardware. Volume 3 continues the presentation of IOA worksheets and contains the potential critical items list, detailed analysis, and the NASA FMEA to IOA worksheet cross reference and recommendations.
    Keywords: SPACE TRANSPORTATION
    Type: NASA-CR-185528-VOL-3 , NAS 1.26:185528-VOL-3 , REPT-1.0-WP-VA88005-10-VOL-3
    Format: application/pdf
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  • 8
    Publication Date: 2019-06-28
    Description: The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed and analysis of the Communication and Tracking hardware, generating draft failure modes and potential critical items. The IOA results were then compared to the NASA FMEA/CIL baseline. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter Communication and Tracking hardware. Volume 2 continues the presentation of IOA worksheets.
    Keywords: SPACE TRANSPORTATION
    Type: NASA-CR-185528-VOL-2 , NAS 1.26:185528-VOL-2 , REPT-1.0-WP-VA88005-10-VOL-2
    Format: application/pdf
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  • 9
    Publication Date: 2019-06-28
    Description: The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Communication and Tracking hardware. The IOA analysis process utilized available Communication and Tracking hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.
    Keywords: SPACE TRANSPORTATION
    Type: NASA-CR-185582 , NAS 1.26:185582 , REPT-1.0-WP-VA87001-09
    Format: application/pdf
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  • 10
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    Unknown
    In:  Other Sources
    Publication Date: 2019-06-28
    Description: Streamlined package is installed and removed without altering aerodynamic properties of structure being tested. Method uses lightweight materials so that blade balance is maintained.
    Keywords: MECHANICS
    Type: LAR-11201 , NASA Tech Briefs (ISSN 0145-319X); 4; 3; P. 404
    Format: text
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