11,206 research outputs found

    Monterey Bay study

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    The multispectral scanner capabilities of LANDSAT 1 were tested over California's Monterey Bay area and portions of the San Joaquin Valley. Using both computer aided and image interpretive processing techniques, the LANDSAT 1 data were analyzed to determine their potential application in terms of land use and agriculture. Utilizing LANDSAT 1 data, analysts were able to provide the identifications and areal extent of the individual land use categories ranging from very general to highly specific levels (e.g., from agricultural lands to specific field crop types and even the different stages of growth). It is shown that the LANDSAT system is useful in the identification of major crop species and the delineation of numerous land use categories on a global basis and that repeated surveillance would permit the monitoring of changes in seasonal growth characteristics of crops as well as the assessment of various cultivation practices with a minimum of onsite observation. The LANDSAT system is demonstrated to be useful in the planning and development of resource programs on earth

    Estimation of Standardized Effort in the Heterogeneous Gulf of Mexico Shrimp Fleet

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    In this paper we estimate nominal and standardized shrimping effort in the Gulf of Mexico for the years 1965 through 1993. We accomplish this by first developing a standardization method (model) and then an expansion method (model). The expansion model estimates nominal days fished for noninterview landings data. The standardization model converts nominal days fished to standard days fished. We then characterize the historical trends of the penaeid shrimp fishery byvessel configuration, relative fishing power, and nominal and standardized effort. Wherever possible, we provide comparison with previous estimates by the National Marine Fisheries Service, NOAA

    The results of an agricultural analysis of the ERTS-1 MSS data at the Johnson Space Center

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    The initial analysis of the ERTS-1 multispectral scanner (MSS) data at the Johnson Space Center (JSC), Houston, Texas is discussed. The primary data set utilized was the scene over Monterey Bay, California, on July 25, 1972, NASA ERTS ID No. 1002-18134. It was submitted to both computerized and image interpretative processing. An area in the San Joaquin Valley was submitted to an intensive evaluation of the ability of the data to (1) discriminate between crop types and (2) to provide a reasonably accurate area measurement of agricultural features of interest. The results indicate that the ERTS-1 MSS data is capable of providing the identifications and area extent of agricultural lands and field crop types

    Niche construction in quantitative traits: Heritability and response to selection

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    A central tenet of niche construction (NC) theory is that organisms can alter their environments in heritable and evolutionarily important ways, often altering selection pressures. We suggest that the physical changes niche constructors make to their environments may also alter trait heritability and the response of phenotypes to selection. This effect might change evolution, over and above the effect of NC acting via selection alone. We develop models of trait evolution that allow us to partition the effects of NC on trait heritability from those on selection to better investigate their distinct effects. We show that the response of a phenotype to selection and so the pace of phenotypic change can be considerably altered in the presence of NC and that this effect is compounded when trans-generational interactions are included. We argue that novel mathematical approaches are needed to describe the simultaneous effects of NC on trait evolution via selection and heritability. Just as indirect genetic effects have been shown to significantly increase trait heritability, the effects of NC on heritability in our model suggest a need for further theoretical development of the concept of heritability

    Adaptive co-evolution of mitochondria and the Y-chromosome: A resolution to conflict between evolutionary opponents

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    Abstract In most species with motile sperm, male fertility depends upon genes located on the Y-chromosome and in the mitochondrial genome. Coordinated adaptive evolution for the function of male fertility between genes on the Y and the mitochondrion is hampered by their uniparental inheritance in opposing sexes: The Y-chromosome is inherited uniparentally, father to son, and the mitochondrion is inherited maternally, mother to offspring. Preserving male fertility is problematic, because maternal inheritance permits mitochondrial mutations advantageous to females, but deleterious to male fertility, to accumulate in a population. Although uniparental inheritance with sex-restricted adaptation also affects genes on the Y-chromosome, females lack a Y-chromosome and escape the potential maladaptive consequences of male-limited selection. Evolutionary models have shown that mitochondrial mutations deleterious to male fertility can be countered by compensatory evolution of Y-linked mutations that restore it. However, direct adaptive coevolution of Y- and mitochondrial gene combinations has not yet been mathematically characterized. We use population genetic models to show that adaptive coevolution of Y and mitochondrial genes are possible when Y-mt gene combinations have positive effects on male fertility and populations are inbred

    Electroencephalograms of Kittens Exhibiting Spastic Behavior

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    Examination and comparison of some basic reflex tests and of the electroencephalograms of five kittens showing spastic behavior with a control permitted the grouping of these animals into categories which were in accord with those previously determined on the basis of behavioral observation only

    Prevalence of working smoke alarms in local authority inner city housing: randomised controlled trial

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    Objectives To identify which type of smoke alarm is most likely to remain working in local authority inner city housing, and to identify an alarm tolerated in households with smokers. Design Randomised controlled trial. Setting Two local authority housing estates in inner London. Participants 2145 households. Intervention Installation of one of five types of smoke alarm (ionisation sensor with a zinc battery; ionisation sensor with a zinc battery and pause button; ionisation sensor with a lithium battery and pause button; optical sensor with a lithium battery; or optical sensor with a zinc battery). Main outcome measure Percentage of homes with any working alarm and percentage in which the alarm installed for this study was working after 15 months. Results 54.4% (1166/2145) of all households and 45.9% (465/1012) of households occupied by smokers had a working smoke alarm. Ionisation sensor, lithium battery, and there being a smoker in the household were independently associated with whether an alarm was working (adjusted odds ratios 2.24 (95% confidence interval 1.75 to 2.87), 2.20 (1.77 to 2.75), and 0.62 (0.52 to 0.74)). The most common reasons for non-function were missing battery (19%), missing alarm (17%), and battery disconnected (4%). Conclusions Nearly half of the alarms installed were not working when tested 15 months later. Type of alarm and power source are important determinants of whether a household had a working alarm

    The prediction and management of aquatic nitrogen pollution across Europe: an introduction to the Integrated Nitrogen in European Catchments project (INCA)

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    Excess nitrogen in soils, fresh water, estuarine and marine systems contributes to nutrient enrichment in key ecosystems throughout Europe, often leading to detrimental environmental impacts, such as soil acidification or the eutrophication of water bodies. The Integrated Nitrogenmodel for European Catchments (INCA) project aims to develop a generic version of the Integrated Nitrogen in Catchments (INCA) model to simulate the retention and transport of nitrogen within river systems, thereby providing a tool to aid the understanding of nitrogen dynamics and for river-basin management/policy-making. To facilitate the development of the model, 10 partners have tested the INCA model with data collected in study sites located in eight European countries as part of the INCA project. This paper summarises the key nitrogen issues within Europe, describes the main aims and methodology of the INCA project, and sets the project in the context of the current major research initiatives at a European level.</p> <p style='line-height: 20px;'><b>Keywords: </b>Europe, European Union, nitrogen, nitrate, ammonium, river basin management, modelling, water chemistry, acidification, eutrophication, Water Framework Directive, INCA
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