1,473 research outputs found

    Autonomous Integrated Receive System (AIRS) requirements definition. Volume 2: Design and development

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    Functional requirements and specifications are defined for an autonomous integrated receive system (AIRS) to be used as an improvement in the current tracking and data relay satellite system (TDRSS), and as a receiving system in the future tracking and data acquisition system (TDAS). The AIRS provides improved acquisition, tracking, bit error rate (BER), RFI mitigation techniques, and data operations performance compared to the current TDRSS ground segment receive system. A computer model of the AIRS is used to provide simulation results predicting the performance of AIRS. Cost and technology assessments are included

    Satellite Data Transmission (SDT) requirement

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    An 85 Mb/s modem/codec to operate in a 34 MHz C-band domestic satellite transponder at a system carrier to noise power ratio of 19.5 dB is discussed. Characteristics of a satellite channel and the approach adopted for the satellite data transmission modem/codec selection are discussed. Measured data and simulation results of the existing 50 Mbps link are compared and used to verify the simulation techniques. Various modulation schemes that were screened for the SDT are discussed and the simulated performance of two prime candidates, the 8 PSK and the SMSK/2 are given. The selection process that leads to the candidate codec techniques are documented and the technology of the modem/codec candidates is assessed. Costs of the modems and codecs are estimated

    Whole Farm Net Zero: approaches to quantification of climate regulation ecosystem services at the whole farm scale. Vermont Payment for Ecosystem Services Technical Report #7

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    In this report, approaches to the quantification of climate mitigation ecosystem services at the whole farm scale are reviewed and summarized for easy comparison. Eight quantification tools, and three case studies demonstrating possible tool applications, are summarized to fulfill the requirements of the Technical Services Contract—Task 7. Information from a combination of literature review and expert interviews served to document the inputs, outputs, strengths, weaknesses, opportunities, and threats for each quantification tool. This research was conducted in service to the Vermont Soil Health and Payment for Ecosystem Services (PES) Working Group (VT PES working group). It is our hope that this report provides productive information and insights for the implementation of whole farm scale payment for ecosystem services programs, Vermont’s Climate Action Plan, and similar efforts elsewhere. Emissions reductions on farms are of interest to farmers in Vermont and will be required by the implementation of the Global Warming Solutions Act (GWSA). Management changes that reduce emissions at the farm scale could possibly be supported and encouraged through a PES program. Given the work and goals of the PES Working Group and the requirements to implement the GWSA it is critical to understand the degree of accuracy and scope of currently available greenhouse gas assessment tools that could possibly be implemented to measure and monitor outcomes from VT agriculture. Section 2 of this report describes the methods used to collect information reviewing eight tools for quantifying agricultural greenhouse gas emissions and sequestration rates, including the CarbOn Management & Emissions Tool (COMET)-Farm, COMET-Planner, COOL-Farm, DayCent, DNDC (DeNitrification-DeComposition), Environmental Policy Integrated Climate (EPIC) & APEX Agricultural Policy / Environmental eXtender (APEX), Holos, and the Integrated Farm Systems Model (IFSM). These eight tools were each reviewed using a systematic literature review, interviews with experts who are well-versed in using the specific tools, and a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis. Section 3 presents some larger-context considerations for choosing an appropriate tool. Section 4 gives a high-level overview of the SWOT analysis performed for each tool reviewed for this task. Section 5 describes three example applications of emissions modeling tools.Section 6 contains concluding remarks. The report’s Appendix section includes the SWOT analyses for each tool to allow for more in-depth review, as well as a series of tables to present a high-level comparison of the tools

    Field scale soil health scenarios. Vermont Payment for Ecosystem Services Technical Report #2

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    This report illustrates how changes in management on Vermont farms can influence soil health metrics at the field scale. We’ve used regionally relevant science-based scenarios to demonstrate how selected soil health metrics that are associated with ecosystem services could change on farms in response to management practices at the field scale. These field scale management scenarios demonstrate that many practices in use by farmers in Vermont can have positive impacts on the soil health indicators of interest to the Vermont Soil Health & Payment for Ecosystem Services Working Group. The scenarios document potential for tradeoffs among soil health properties. Specifically, some of the scenarios illustrate how bulk density and compaction can worsen in instances when other soil health properties improve. Long-term research that measures multiple indicators of soil health and ecosystem services on recommended soil health management practices in Vermont is needed to support the evidence-base for soil health and ecosystem services incentive programs

    Long-Lasting Impairments in Quadriceps Mitochondrial Health, Muscle Size, and Phenotypic Composition Are Present After Non-Invasive Anterior Cruciate Ligament Injury

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    Introduction: Despite rigorous rehabilitation aimed at restoring muscle health, anterior cruciate ligament (ACL) injury is often hallmarked by significant long-term quadriceps muscle weakness. Derangements in mitochondrial function are a common feature of various atrophying conditions, yet it is unclear to what extent mitochondria are involved in the detrimental sequela of quadriceps dysfunction after ACL injury. Using a preclinical, non-invasive ACL injury rodent model, our objective was to explore the direct effect of an isolated ACL injury on mitochondrial function, muscle atrophy, and muscle phenotypic transitions. Methods: A total of 40 male and female, Long Evans rats (16-week-old) were exposed to non-invasive ACL injury, while 8 additional rats served as controls. Rats were euthanized at 3, 7, 14, 28, and 56 days after ACL injury, and vastus lateralis muscles were extracted to measure the mitochondrial respiratory control ratio (RCR; state 3 respiration/state 4 respiration), mitochondrial reactive oxygen species (ROS) production, fiber cross sectional area (CSA), and fiber phenotyping. Alterations in mitochondrial function and ROS production were detected using two-way (sex:group) analyses of variance. To determine if mitochondrial characteristics were related to fiber atrophy, individual linear mixed effect models were run by sex. Results: Mitochondria-derived ROS increased from days 7 to 56 after ACL injury (30–100%, P \u3c 0.05), concomitant with a twofold reduction in RCR (P \u3c 0.05). Post-injury, male rats displayed decreases in fiber CSA (days 7, 14, 56; P \u3c 0.05), loss of IIa fibers (day 7; P \u3c 0.05), and an increase in IIb fibers (day 7; P \u3c 0.05), while females displayed no changes in CSA or phenotyping (P \u3e 0.05). Males displayed a positive relationship between state 3 respiration and CSA at days 14 and 56 (P \u3c 0.05), while females only displayed a similar trend at day 14 (P = 0.05). Conclusion: Long-lasting impairments in quadriceps mitochondrial health are present after ACL injury and play a key role in the dysregulation of quadriceps muscle size and composition. Our preclinical data indicate that using mitoprotective therapies may be a potential therapeutic strategy to mitigate alterations in muscle size and characteristic after ACL injury
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