989 research outputs found
Using Moored Arrays and Hyperspectral Aerial Imagery to Develop Nutrient Criteria for New Hampshire\u27s Estuaries
Increasing nitrogen concentrations and declining eelgrass beds in Great Bay, NH are clear indicators of impending problems for the state’s estuaries. A workgroup established in 2005 by the NH Department of Environmental Services and the NH Estuaries Project (NHEP) adopted eelgrass survival as the water quality target for nutrient criteria development for NH’s estuaries. In 2007, the NHEP received a grant from the U.S. Environmental Protection Agency to collect water quality information including that from moored sensors and hyper-spectral imagery data of the Great Bay Estuary. Data from the Great Bay Coastal Buoy, part of the regional Integrated Ocean Observing System (IOOS), were used to derive a multivariate model of water clarity with phytoplankton, Colored Dissolved Organic Matter (CDOM), and non-algal particles. Non-algal particles include both inorganic and organic matter. Most of the temporal variability in the diffuse attenuation coefficient of Photosynthetically Available Radiation (PAR) was associated with non-algal particles. However, on a mean daily basis non-algal particles and CDOM contributed a similar fraction (~30 %) to the attenuation of light. The contribution of phytoplankton was about a third of the other two optically important constituents. CDOM concentrations varied with salinity and magnitude of riverine inputs demonstrating its terrestrial origin. Non-algal particle concentration also varied with river flow but also wind driven resuspension. Twelve of the NHEP estuarine assessment zones were observed with the hyperspectral aerial imagery on August 29 and October 17. A concurrent in situ effort included buoy measurements, continuous along-track sampling, discrete water grab samples, and vertical profiles of light attenuation. PAR effective attenuation coefficients retrieved from deep water regions in the imagery agreed well with in-situ observations. Water clarity was lower and optically important constituent concentrations were higher in the tributaries. Eelgrass survival depth, estimated as the depth at which 22% of surface light was available, ranged from less than half a meter to over two meters. The best water clarity was found in the Great Bay (GB), Little Bay (LB), and Lower Piscataqua River (LPR) assessment zones. Absence of eelgrass from these zones would indicate controlling factors other than water clarity
Dynamic nuclear polarization from current-induced electron spin polarization
Current-induced electron spin polarization is shown to produce nuclear
hyperpolarization through dynamic nuclear polarization. Saturated fields of
several millitesla are generated upon the application of electric field over a
timescale of a hundred seconds in InGaAs epilayers and measured using optical
Larmor magnetometry. The dependence on temperature, external magnetic field,
and applied voltage is investigated. We find an asymmetry in which the
saturation nuclear field depends on the relative alignment of the electrically
generated spin polarization and the external magnetic field, which we attribute
to an interplay between various electron spin dynamical processes.Comment: 5 pages, 4 figure
A Cultural Resources Investigation For The Ramsey North Residue Line Project, Reeves And Culberson Counties, Texas
This report details the results of an intensive archaeological survey by SWCA Environmental Consultants (SWCA) for the proposed Ramsey North Residue Line (Residue Line). The 51-cmdiameter (20-inch-diameter) Residue Line will be located in Reeves and Culberson Counties, Texas (2.35 and 7.21 km [1.46 and 4.48 miles], respectively) and Eddy County, New Mexico (4.83 km [3.0 miles]). The line will start at the Ramsey Gas Plant in Reeves County, Texas, and then run northwest for approximately 14.5 km (9 miles), largely following existing rights-of-way (ROWs). The Residue Line will be constructed in a 15-m-wide (50-foot-wide) ROW. The 15-m (50-foot) ROW in Texas and New Mexico will consist of 6 m (20 feet) of temporary ROW to be used only during construction and 9 m (30 feet) of permanent ROW. The pipeline will be strung along the pipeline route as it arrives at the site, so there will be no additional staging areas needed. Five horizontal direction drills (HDDs) are anticipated at two county road crossings, the crossing of the Delaware River, crossing an historic ditch, and at an abandoned railroad grade. In addition to proposed pipeline, there is also a proposed surface facility that will be located on a 61 × 61–m (200 × 200–foot) (approximately 1-acre) site with a short (75 m; 245 feet) access road. The surface facility will include a coalesce separator, a measuring station that will meter the gas prior to the tie-in with the KM lines, and a temporary diesel generator until a permanent power source is available. This report includes the findings of the cultural resources investigations within the Texas portion of the project.
Sound Environmental Solutions, Inc. selected SWCA to conduct an intensive pedestrian archaeological survey of the area of potential effect (APE) to aid in complying with Section 106 of the National Historic Preservation Act. The fieldwork was completed between February 11 and 19, 2015. The Texas portion of the project is entirely on private lands with the exception of one small segment that crosses state lands. The project will be permitted by the Federal Energy Regulatory Commission (FERC) as well as the Texas Historical Commission (THC) (Antiquities Permit #7262), which is mandated by the inclusion of public lands within the project APE.
The SWCA archaeological investigations were conducted within a 45.7-m-wide (150-foot-wide) corridor totaling approximately 9.56 km (5.94 miles) of the overall project length within Texas. The Texas portion of the project area is depicted on the Red Bluff and Screw Bean Draw NE U.S. Geological Survey 7.5-minute topographic quadrangles. The survey in Texas recorded one newly discovered archaeological site (41CU804). The site is an abandoned railroad grade with an associated historic assemblage and is recommended undetermined for the National Register of Historic Places. The site will be avoided by boring under the site, and there will be no impact to the site. No further management is recommended for this site associated with this project.
In accordance with 33 Code of Federal Regulations (CFR) 325, Appendix C, and Section 106 of the National Historic Preservation Act (36 CFR 800.4), SWCA has made a reasonable and good faith effort to identify historic properties within the proposed project area. Based on the results of the current effort, it is SWCA’s opinion that the proposed Texas portion of the project would have no adverse effect on significant cultural resources within the investigated project area. As such, SWCA recommends no further archaeological investigations within the investigated project area and that the project be allowed to proceed
Enhancing aviation safety: Addressing miscommunication between pilots and air traffic controllers
Miscommunication in aviation refers to the misinterpretation of instructions by the pilots or controllers that is indicated by the absence of readback or incomplete instruction. Clear communication between pilots and air traffic controllers is vital for safe and efficient aircraft operations, preventing potential disasters. In the years 1999-2019, miscommunication contributed to 37,908 aviation accidents, emphasizing the urgent need for improved communication protocols. This poster categorizes aviation miscommunications into groups such as no communication, language barriers, phraseology problems, and misunderstandings stemming from accents or vocabulary differences. The objectives of this poster are identifying forms of miscommunication and evaluating their impact on safety. Recommendations offered to enhance aviation safety include improved training and proficiency assessments, standardized phraseology, advanced frequency management technology, and language proficiency requirements for international flights. This poster benefits aviation authorities, airlines, controllers, and pilots by providing practical suggestions to mitigate miscommunication risks, ultimately ensuring passenger safety and operational efficiency
The Deep Space Network: A Radio Communications Instrument for Deep Space Exploration
The primary purpose of the Deep Space Network (DSN) is to serve as a communications instrument for deep space exploration, providing communications between the spacecraft and the ground facilities. The uplink communications channel provides instructions or commands to the spacecraft. The downlink communications channel provides command verification and spacecraft engineering and science instrument payload data
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Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis)
Trees are suffering mortality across the globe as a result of drought, warming, and biotic attacks. The combined effects of warming and drought on in situ tree chemical defenses against herbivory have not been studied to date. To address this, we transplanted mature pinon pine trees-a well-studied species that has undergone extensive drought and herbivore-related mortality-within their native woodland habitat and also to a hotter-drier habitat and measured monoterpene emissions and concentrations across the growing season. We hypothesized that greater needle temperatures in the hotter-drier site would increase monoterpene emission rates and consequently lower needle monoterpene concentrations, and that this temperature effect would dominate the seasonal pattern of monoterpene concentrations regardless of drought. In support of our hypothesis, needle monoterpene concentrations were lower across all seasons in trees transplanted to the hotter-drier site. Contrary to our hypothesis, basal emission rates (emission rates normalized to 30 degrees C and a radiative flux of 1000 mu mol m(-2) s(-1)) did not differ between sites. This is because an increase in emissions at the hotter-drier site from a 1.5 degrees C average temperature increase was offset by decreased emissions from greater plant water stress. High emission rates were frequently observed during June, which were not related to plant physiological or environmental factors but did not occur below pre-dawn leaf water potentials of -2 MPa, the approximate zero carbon assimilation point in pinon pine. Emission rates were also not under environmental or plant physiological control when pre-dawn leaf water potential was less than -2 MPa. Our results suggest that drought may override the effects of temperature on monoterpene emissions and tissue concentrations, and that the influence of drought may occur through metabolic processes sensitive to the overall needle carbon balance.National Science Foundation, Division of Atmospheric and Geospace Sciences [0919189]; USDA National Institute of Food and Agriculture Hatch project [MONB00389, 228396]; National Science Foundation, Division of Integrative Organismal Systems [1755346]; National Science Foundation Division of Environmental Biology [1552976]; Department of the Energy National Institute for Climate Change Research (Western Region) [DE-FCO2-O6ER64159]; National Science Foundation Macrosystems Biology [EF-1340624, EF-1550756]; Critical Zone Observatories [EAR-1331408]; DIRENet [DEB-0443526]; Biosphere 2 through the Philecology Foundation (Fort Worth, TX); US Environmental Protection Agency (STAR Fellowship Assistance Agreement) [FP-91717801-0]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
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Novel Polyoxometalate Containing Membranes for PEM Fuel Cells
Current proton exchange membrane (PEM) technologies are inadequate to address the projected needs for fuel cell performance above 80 ºC. Continuing research into traditional ion carriers in novel membrane materials offers the promise of marginal improvement, representing only an evolutionary increase in performance. This conclusion is supported by the role of water in conduction. Thus, the key to better PEMs is not to eliminate water, but to change the role of water by developing ion carriers that will bind water more tightly than traditional sulfur or phosphorus based carriers resulting in materials that will conduct at higher temperatures. This change entails having a carrier structure that interacts more intimately with water and by increasing the ion carrier anionic charge to result in more tightly held inner shell protonated waters of hydration. Both of these factors synergistically act to maintain a critical water concentration at the carrier necessary for conduction. In this work, polyoxometalate (POM) clusters were selected to serve as these different proton carriers
Tree defence and bark beetles in a drying world: carbon partitioning, functioning and modelling
Drought has promoted large‐scale, insect‐induced tree mortality in recent years, with severe consequences for ecosystem function, atmospheric processes, sustainable resources and global biogeochemical cycles. However, the physiological linkages among drought, tree defences, and insect outbreaks are still uncertain, hindering our ability to accurately predict tree mortality under on‐going climate change. Here we propose an interdisciplinary research agenda for addressing these crucial knowledge gaps. Our framework includes field manipulations, laboratory experiments, and modelling of insect and vegetation dynamics, and focuses on how drought affects interactions between conifer trees and bark beetles. We build upon existing theory and examine several key assumptions: 1) there is a trade‐off in tree carbon investment between primary and secondary metabolites (e.g. growth vs. defence); 2) secondary metabolites are one of the main component of tree defence against bark beetles and associated microbes; and 3) implementing conifer‐bark beetle interactions in current models improves predictions of forest disturbance in a changing climate. Our framework provides guidance for addressing a major shortcoming in current implementations of large‐scale vegetation models, the under‐representation of insect‐induced tree mortality
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