3,173 research outputs found

    Modified Gravity and Dark Energy models Beyond w(z)w(z)CDM Testable by LSST

    Get PDF
    One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to uncover the nature of cosmic acceleration. In the base analysis, possible deviations from the Lambda-Cold-Dark-Matter (Λ\LambdaCDM) background evolution will be probed by fitting a w(z)w(z)CDM model, which allows for a redshift-dependent dark energy equation of state with w(z)w(z), within general relativity (GR). A rich array of other phenomena can arise due to deviations from the standard Λ\LambdaCDM+GR model though, including modifications to the growth rate of structure and lensing, and novel screening effects on non-linear scales. Concrete physical models are needed to provide consistent predictions for these (potentially small) effects, to give us the best chance of detecting them and separating them from astrophysical systematics. A complex plethora of possible models has been constructed over the past few decades, with none emerging as a particular favorite. This document prioritizes a subset of these models along with rationales for further study and inclusion into the LSST Dark Energy Science Collaboration (DESC) data analysis pipelines, based on their observational viability, theoretical plausibility, and level of theoretical development. We provide references and theoretical expressions to aid the integration of these models into DESC software and simulations, and give justifications for why other models were not prioritized. While DESC efforts are free to pursue other models, we provide here guidelines on which theories appear to have higher priority for collaboration efforts due to their perceived promise and greater instructional value.Comment: 61 pages. Some acknowledgments and references added. This is version-1.1 of an internal collaboration document of LSST-DESC that is being made public and is not planned for submission to a journa

    Effects of Disking Versus Feed Patch Management on Northern Bobwhite Brood Habitat and Hunting Success

    Get PDF
    More than 60 years ago, Herbert Stoddard (1931:376) wrote there is little doubt that such methods [i.e., disking and harrowing] are more practical for Southeastern quail preserves than artificial plantings, which are costly on a large scale and not always effective. Incredibly, this statement, and testing it as an hypothesis, has been ignored by the bobwhite research community until the past 10 years. Therefore, we designed a pilot study to compare measures of northern bobwhite (Colinus virginianus) brood habitat (vegetation composition and arthropod biomass) and direct measures of hunting success (covey finds per half-day hunt) to test whether feed patches were really necessary for bobwhite habitat management in southern Georgia and northern Florida. We applied experimental treatments (disk only versus feed patch planting) by using shooting courses (150-250 ha each) on 2 southeastern shooting plantations during 1994, 1995 and 1996. Overall, results were equivocal between the feed patch and disking treatments; no consistent pattern or difference in brood habitat composition or hunting success was observed. One factor responsible for this pattern may be the relatively fine-grained scale (only 1-3% of the shooting courses were planted or disked) at which treatments were applied were insufficient to significantly influence bobwhite abundance. Further research using increased amounts of ground disturbance and planting (5%, 10%, 20%, etc.) will be required before the actual need for agricultural plantings can be determined in the context of their efficacy for bobwhite management. One potential result of these findings is that significant cost savings can be realized by disking rather than planting agricultural crop plants because at least 70% of the costs of planting are a function of seed, fertilizer and cultivation, whereas only about 30% are attributed to disking

    Effects of Seasonal Fire Applications on Northern Bobwhite Brood Habitat and Hunting Success

    Get PDF
    Since the early part of the 20th century, land managers have used prescribed fire during February and March to maintain and enhance habitat for northern bobwhites (Colinus virginianus) in southern pine forests. During the past 2 decades, some managers have started to shift their use of fire to mimic more natural lightning-season (April to August) ignitions because these fires encourage flowering of plants in intact native ground cover, and are potentially more effective at hardwood control than winter fires. Therefore, we designed a short-term pilot study to evaluate whether seasonal applications of prescribed fire had any effect on bobwhite brood habitat (as measured by vegetation composition and arthropod biomass) or bobwhite abundance (as measured by hunting success) during the subsequent fall. During the first two years of our study (1994 and 1995), results showed that arthropod biomass and bobwhite hunting success were slightly greater on the shooting course burned during lightning-season (May) than the one burned during February and March. These results indicate that applications of lightning-season fire can be used, at least on a small scale (i.e., management blocks \u3c250 ha) in southern pine forests for hardwood control, and possibly enhancement of native ground cover without short-term negative impacts on northern bobwhites

    Northern Bobwhite Response to Control of Red Imported Fire Ants in the Gulf Coast Prairie of Texas

    Get PDF
    The population decline of northern bobwhite (Colinus virginianus; hereafter, bobwhite) on the Texas Gulf Coast Prairie, USA is largely attributed to habitat loss. However, red imported fire ants (Solenopsis invicta) occur throughout the region and are considered a possible contributing factor to the bobwhite decline. The objectives of our study were to determine the influence of red imported fire ants on bobwhites by comparing bobwhite nest success, survival, and density between sites treated with fire ant bait (treatment) and reference (control) sites. Our study was conducted on 3 private ranches in Goliad and Refugio counties, Texas. Each ranch contained 2 paired experimental units that consisted of a treatment and control site (500 ha each). The treatment sites received an aerial application of fire ant bait (Extinguish® Plus) during April 2018, whereas the control sites were not treated. We estimated mound density by counting fire ant mounds using distance sampling. We used radio-telemetry to monitor bobwhite nest success and survival, and we estimated bobwhite densities using distance sampling via helicopter surveys. Fire ant mound density decreased through time on both treatment and control sites. However, fire ant mound density was lower on treatment sites than control sites, indicating the insecticide was effective at decreasing fire ant mound density. Bobwhite survival, nest success, and density did not statistically differ between control and treated sites either pre-treatment (2017) or post-treatment (2018), but survival and nest success metrics were numerically higher in treated units. Bobwhite survival remained relatively stable in the treatment units 4 weeks after application but decreased in the control units. Following treatment, apparent nest success in the treated units increased by 37.4% while nest success in the control units decreased by 35.2%. Bobwhite populations were low in this ecoregion, which influenced our ability to trap and monitor many bobwhites or monitor many nests. In addition, it may be possible that repeated, annual treatments for fire ants are necessary for a benefit to accrue and be observed in bobwhites. Our results indicate that there may be potential benefits to bobwhites from fire ant reduction that deserve further research attention

    Pinedale Glacial History of the Upper Arkansas River Valley: New Moraine Chronologies, Modeling Results and Geologic Mapping

    Get PDF
    This field trip guidebook chapter outlines the glacial history of the upper Arkansas River valley, Colorado, and builds on a previous GSA field trip to the same area in 2010. The following will be presented: (1) new cosmogenic 10Be exposure ages of moraine boulders from the Pinedale and Bull Lake glaciations (Marine Isotope Stages 2 and 6, respectively) located adjacent to the Twin Lakes Reservoir, (2) numerical modeling of glaciers during the Pinedale glaciation in major tributaries draining into the upper Arkansas River, (3) discharge estimates for glacial-lake outburst floods in the upper Arkansas River valley, and (4) 10Be ages on flood boulders deposited downvalley from the moraine sequences. This research was stimulated by a new geologic map of the Granite 7.5’ quadrangle, in which the mapping of surficial deposits was revised based in part on the interpretation of newly acquired LiDAR data and field investigations. The new 10Be ages of the Pinedale terminal moraine at Twin Lakes average 21.8 ± 0.7 ka (n=14), which adds to nearby Pinedale terminal moraine ages of 23.6 ± 1.4 ka (n=5), 20.5 ± 0.2 ka (n=3) and 16.6 ± 1.0 ka, and downvalley outburst flood terraces that date to 20.9 ± 0.9 ka (n=4) and 19.0 ± 0.6 ka (n=4). This growing chronology leads to improved understanding of the controls and timing of glaciation in the western U.S., the modeling of glacial-lake outburst flooding, and the reconstruction of paleo-temperature through glacier modeling

    Survival and growth responses of eight Everglades tree species along an experimental hydrological gradient on two tree island types

    Get PDF
    Questions: How are the early survival and growth of seedlings of Everglades tree species planted in an experimental setting on artificial tree islands affected by hydrology and substrate type? What are the implications of these responses for broader tree island restoration efforts? Location: Loxahatchee Impoundment Landscape Assessment (LILA), Boynton Beach, Florida, USA. Methods: An experiment was designed to test hydrological and substrate effects on seedling growth and survivorship. Two islands – a peat and a limestone-core island representing two major types found in the Everglades – were constructed in four macrocosms. A mixture of eight tree species was planted on each island in March of 2006 and 2007. Survival and height growth of seedlings planted in 2006 were assessed periodically during the next two and a half years. Results: Survival and growth improved with increasing elevation on both tree island substrate types. Seedlings\u27 survival and growth responses along a moisture gradient matched species distributions along natural hydrological gradients in the Everglades. The effect of substrate on seedling performance showed higher survival of most species on the limestone tree islands, and faster growth on their peat-based counterparts. Conclusions: The present results could have profound implications for restoration of forests on existing landforms and artificial creation of tree islands. Knowledge of species tolerance to flooding and responses to different edaphic conditions present in wetlands is important in selecting suitable species to plant on restored tree island

    Real-time analysis and display of quantitative measures to track and improve clinical workflow

    Get PDF
    PURPOSE: Radiotherapy treatment planning is a complex process with multiple, dependent steps involving an interdisciplinary patient care team. Effective communication and real-time tracking of resources and care path activities are key for clinical efficiency and patient safety. MATERIALS AND METHODS: We designed and implemented a secure, interactive web-based dashboard for patient care path, clinical workflow, and resource utilization management. The dashboard enables visualization of resource utilization and tracks progress in a patient\u27s care path from the time of acquisition of the planning CT to the time of treatment in real-time. It integrates with the departmental electronic medical records (EMR) system without the creation and maintenance of a separate database or duplication of work by clinical staff. Performance measures of workflow were calculated. RESULTS: The dashboard implements a standardized clinical workflow and dynamically consolidates real-time information queried from multiple tables in the EMR database over the following views: (1) CT Sims summarizes patient appointment information on the CT simulator and patient load; (2) Linac Sims summarizes patient appointment times, setup history, and notes, and patient load; (3) Task Status lists the clinical tasks associated with a treatment plan, their due date, status and ownership, and patient appointment details; (4) Documents provides the status of all documents in the patients\u27 charts; and (5) Diagnoses and Interventions summarizes prescription information, imaging instructions and whether the plan was approved for treatment. Real-time assessment and quantification of progress and delays in a patient\u27s treatment start were achieved. CONCLUSIONS: This study indicates it is feasible to develop and implement a dashboard, tailored to the needs of an interdisciplinary team, which derives and integrates information from the EMR database for real-time analysis and display of resource utilization and clinical workflow in radiation oncology. The framework developed facilitates informed, data-driven decisions on clinical workflow management as we seek to optimize clinical efficiency and patient safety
    • …
    corecore