2,702 research outputs found

    21-cm H I emission from the Damped Lyman-alpha absorber SBS 1543+593

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    We detect 21-cm emission from the Low Surface Brightness (LSB) galaxy SBS 1543+593, which gives rise to a Damped Lyman-alpha (DLA) absorption line in the spectrum of the background QSO HS 1543+5921 (z=0.807). We obtain an accurate measure of the velocity of the H I gas in the LSB galaxy, v=2868 km/s, and derive a mass of 1.3e9 solar masses. We compare this value with limits obtained towards two other z~0.1 DLA systems, and show that SBS 1543+593 would not have been detected. Hence LSB galaxies similar to SBS 1543+593 can be responsible for DLA systems at even modest redshifts without being detectable from their 21-cm emission.Comment: 4 pages, 1 figure, accepted for publication in A&

    Indigenous Knowledge of Hydrologic Change in the Yukon River Basin: A Case Study of Ruby, Alaska

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    In the Arctic and Subarctic, the contribution of Indigenous knowledge to understanding environmental change has been established over the last several decades. This paper explores the role of Indigenous knowledge of water in understanding hydrologic change within complex social-ecological systems. Observations of hydrology in the Yukon River Basin, contributed by 20 community experts from Ruby Village, Alaska, in semi-structured interviews, are compared with findings from scientific literature to illustrate the commonalities and differences. Research findings reveal the contribution of Indigenous knowledge to understandings of hydrologic change in the Yukon River and its tributaries, which includes insights regarding alterations in sediment and river ice regimes. Recommendations for future research that incorporates Indigenous knowledge of water to gain insight into hydrologic changes in the watershed include combining multiple case studies that are distributed geographically. Our findings suggest 1) that using participatory research approaches to research will help ensure that it benefits the communities whose livelihoods are affected by hydrologic changes, and 2) that a multidisciplinary approach that combines qualitative and quantitative methods from the social and biophysical sciences would be most effective to help us understand and respond to hydrologic changes.Dans l’Arctique et la région subarctique, l’apport des connaissances indigènes à l’égard de la compréhension de l’altération de l’environnement a été mis au clair au cours des dernières décennies. Cette communication explore le rôle des connaissances indigènes relativement à l’eau dans la compréhension des changements hydrologiques touchant les systèmes socioécologiques complexes. Les observations hydrologiques dans le bassin du fleuve Yukon, émanant de 20 experts communautaires de Ruby Village, en Alaska et prélevées dans le cadre d’entrevues semi-structurées, sont comparées aux constatations publiées dans des documents scientifiques pour illustrer les points communs et les différences. Les résultats de recherche révèlent l’apport des connaissances indigènes en matière de compréhension des changements hydrologiques caractérisant le fleuve Yukon et ses affluents, ce qui comprend un aperçu de l’altération des sédiments et des régimes de glaces fluviales. Les recommandations de recherches futures faisant appel aux connaissances indigènes de l’eau afin de mieux comprendre les changements hydrologiques du bassin hydrographique préconisent le fait de combiner de nombreuses études de cas géographiquement réparties. Nos constatations suggèrent 1) que le recours à des méthodes de recherche participative aidera à faire en sorte que les collectivités dont le mode de vie est touché par les changements hydrologiques bénéficient des travaux de recherche, et 2) qu’une approche multidisciplinaire dans les domaines des sciences sociales et biophysiques faisant appel à la fois à des méthodes qualitatives et à des méthodes quantitatives s’avérerait plus efficace, et nous aiderait à comprendre les changements hydrologiques puis à y réagir

    Autonomous power expert system

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    The Autonomous Power Expert (APEX) system was designed to monitor and diagnose fault conditions that occur within the Space Station Freedom Electrical Power System (SSF/EPS) Testbed. APEX is designed to interface with SSF/EPS testbed power management controllers to provide enhanced autonomous operation and control capability. The APEX architecture consists of three components: (1) a rule-based expert system, (2) a testbed data acquisition interface, and (3) a power scheduler interface. Fault detection, fault isolation, justification of probable causes, recommended actions, and incipient fault analysis are the main functions of the expert system component. The data acquisition component requests and receives pertinent parametric values from the EPS testbed and asserts the values into a knowledge base. Power load profile information is obtained from a remote scheduler through the power scheduler interface component. The current APEX design and development work is discussed. Operation and use of APEX by way of the user interface screens is also covered

    Rapid Transfer of Abstract Rules to Novel Contexts in Human Lateral Prefrontal Cortex

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    Flexible, adaptive behavior is thought to rely on abstract rule representations within lateral prefrontal cortex (LPFC), yet it remains unclear how these representations provide such flexibility. We recently demonstrated that humans can learn complex novel tasks in seconds. Here we hypothesized that this impressive mental flexibility may be possible due to rapid transfer of practiced rule representations within LPFC to novel task contexts. We tested this hypothesis using functional MRI and multivariate pattern analysis, classifying LPFC activity patterns across 64 tasks. Classifiers trained to identify abstract rules based on practiced task activity patterns successfully generalized to novel tasks. This suggests humans can transfer practiced rule representations within LPFC to rapidly learn new tasks, facilitating cognitive performance in novel circumstances

    Two New Techniques for Evaluating Connectivity of Septic Fields to Great Lake Watersheds and Embayments

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    Pictometry Oblique Imagery was successfully used to map septic fields in Oak Orchard watershed. Analysis of the imagery proved to be efficient for finding leach fields, and between 66 to 81% of the septic fields previously mapped by the Genesee Orleans County Department of Health, were identified. The remainder were not identified because of canopy cover, or were either septic systems without leach fields, the septic field postdated the imagery, or were not visible. Consequently under ideal conditions (septic systems with leach fields and no canopy or shadows) the method should be able to identify over 80% of the systems. Imagery taken during the transition from dormant to growing season proved best for identifying leach fields. One example of a plume from a short circuited system was recorded. A total of 1277 septic fields were mapped in the watershed. Spatial distribution was heterogenous, with dense sites of septic fields concentrated along residential road corridors. Approximately 4.2% of the leach fields were located less than 100 feet of a tributary. This is below the minimum separation distance of a leach field to a waterbody that is required by the NYS Department of Health code. The average distance of a leach field to a tributary is 327 meters with 50% of the leach fields occurring within 240 meters of mapped tributaries. Maps of important septic field “hotspots” were developed for watershed stakeholders and include tributaries along Batavia-Elba Townline Rd., Marsh Creek, and tributaries near the intersections of Alleghany and Lockport Rds, Judge Rd and Knowlesville Rd., and Lockport and Albion Rd. Considerable numbers of septic fields occur along Lake Alice in the main stem of the river, however this stretch is probably diluted by water input from the Erie Canal at the Glendale Dam. In a second set of experiments, a new DNA-based groundwater tracer was introduced to two septic systems to see if it could be used to trace individual septic systems. The tracer was not discovered in one site, however, a breakthrough curve was obtained in the second site 31 days after being introduced into the toilet. This tracer passed through at least 200 meters of groundwater flowpath and 1 km of stream. The results of these experiments suggest that frequent, systematic sampling and careful lab protocols to identify the signal to noise threshold of the procedure are critical to the success of the technique. In summary we suggest that Pictometry Oblique Imagery can be used to map septic fields in a watershed and that the DNA Tracer technique may be successful in some septic systems. Further research needs to be conducted to improve the success of the latter

    CO(1-0) in z ≳ 4 Quasar Host Galaxies: No Evidence for Extended Molecular Gas Reservoirs

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    We present ^(12)CO(J = 1 → 0) observations of the high-redshift quasi-stellar objects (QSOs) BR 1202-0725 (z = 4.69), PSS J2322+1944 (z = 4.12), and APM 08279+5255 (z = 3.91) using the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg 100 m telescope. We detect, for the first time, the CO ground-level transition in BR 1202-0725. For PSS J2322+1944 and APM 08279+5255, our observations result in line fluxes that are consistent with previous NRAO Very Large Array (VLA) observations, but they reveal the full line profiles. We report a typical lensing-corrected velocity-integrated intrinsic ^(12)CO(J = 1 → 0) line luminosity of L'_(CO) = 5 × 10^(10) K km s^(-1) pc^2 and a typical total H_2 mass of M(H_2) = 4 × 10^(10) M_☉ for the sources in our sample. The CO/FIR luminosity ratios of these high-z sources follow the same trend as seen for low-z galaxies, leading to a combined solution of log L_(FIR) = (1.39 ± 0.05) log L_(CO) - 1.76. It has previously been suggested that the molecular gas reservoirs in some quasar host galaxies may exhibit luminous, extended ^(12)CO(J = 1 → 0) components that are not observed in the higher J CO transitions. Using the line profiles and the total intensities of our observations and large velocity gradient (LVG) models based on previous results for higher J CO transitions, we derive that emission from all CO transitions is described well by a single gas component in which all molecular gas is concentrated in a compact nuclear region. Thus, our observations and models show no indication of a luminous extended, low surface brightness molecular gas component in any of the high-redshift QSOs in our sample. If such extended components exist, their contribution to the overall luminosity is limited to at most 30%

    Challenges to implementing bottom-up flood risk decision analysis frameworks: how strong are social networks of flooding professionals?

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    Recent developments in bottom-up vulnerability-based decision analysis frameworks present promising opportunities for flood practitioners to simplify complex decisions regarding risk mitigation and climate adaptation. This family of methodologies relies on strong social networks among flood practitioners and the public to support careful definition of stakeholder-relevant thresholds and vulnerabilities to hazards. In parallel, flood researchers are directly considering distinct atmospheric mechanisms that induce flooding to readily incorporate information on future climate projections. We perform a case study of flood professionals actively engaged in flood risk mitigation within Tompkins County, New York, USA, a community dealing with moderate flooding, to gage how much variance exists among professionals from the perspective of establishing a bottom-up flood mitigation study from an atmospheric perspective. Results of this case study indicate disagreement among flooding professionals as to which socioeconomic losses constitute a flood, disagreement on anticipated community needs, weak understanding of climate–weather–flood linkages, and some disagreement on community perceptions of climate adaptation. In aggregate, the knowledge base of the Tompkins County flood practitioners provides a well-defined picture of community vulnerability and perceptions. Our research supports the growing evidence that collaborative interdisciplinary flood mitigation work could reduce risk, and potentially better support the implementation of emerging bottom-up decision analysis frameworks for flood mitigation and climate adaptation

    Methane Emission in a Specific Riparian-Zone Sediment Decreased with Bioelectrochemical Manipulation and Corresponded to the Microbial Community Dynamics

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    Dissimilatory metal-reducing bacteria are widespread in terrestrial ecosystems, especially in anaerobic soils and sediments. Thermodynamically, dissimilatory metal reduction is more favorable than sulfate reduction and methanogenesis but less favorable than denitrification and aerobic respiration. It is critical to understand the complex relationships, including the absence or presence of terminal electron acceptors, that govern microbial competition and coexistence in anaerobic soils and sediments, because subsurface microbial processes can effect greenhouse gas emissions from soils, possibly resulting in impacts at the global scale. Here, we elucidated the effect of an inexhaustible, ferrous-iron and humic-substance mimicking terminal electron acceptor by deploying potentiostatically poised electrodes in the sediment of a very specific stream riparian zone in Upstate New York state. At two sites within the same stream riparian zone during the course of six weeks in the spring of 2013, we measured CH4 and N2/N2O emissions from soil chambers containing either poised or unpoised electrodes, and we harvested biofilms from the electrodes to quantify microbial community dynamics. At the upstream site, which had a lower vegetation cover and highest soil temperatures, the poised electrodes inhibited CH4 emissions by ~45% (when normalized to remove temporal effects). CH4 emissions were not significantly impacted at the downstream site. N2/N2O emissions were generally low at both sites and were not impacted by poised electrodes. We did not find a direct link between bioelectrochemical treatment and microbial community membership; however, we did find a correspondence between environment/function and microbial community dynamics
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