5,187 research outputs found

    COMPARISON OF RUNOFF AND EROSION IN PRAIRIE, PASTURE, AND CULTIVATED LAND

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    Soil erosion resulting from runoff water has come to be recognized as a national menace. The determination and evaluation of all factors influencing runoff and erosion are studies of fundamental importance, especially insofar as they may be made to yield information upon methods of control over this insidious tendency of washing away the land. Fully 75 per cent of the crop-producing and grazing areas of the United States is sloping enough to set in motion, moderately or violently, these wasteful processes of accelerated soil-removal and excessive runoff. That 35 million acres of formerly cultivated land have been essentially ruined by erosion and that an additional area of about 125 million acres, still largely in cultivation, have lost all or most of the topsoil, with another 100 million acres of crop-land heading in this direction, should be sufficient evidence that the problem is one of profound economic importance. Especially must this be considered true since the wastage is now proceeding faster than ever, owing to the fact that considerable time was required to strip off the more absorptive surface-layer from millions of acres, and to the further fact that the subsoil is generally more erosive than the soil. The cost runs into hundreds of millions of dollars annually, in the way of direct depreciation and essential destruction of fields and pastures, the silting of reservoirs, stream-channels and ditches, damage to highway and railway fills and embankments, choking of culverts, covering of valuable valley-lands with relatively unproductive erosional debris, and pollution of former clear-water streams with excessive loads of silt and clay washed out of the hills (Bennett, \u2734). Much experimentation has been carried on and numerous papers have been written on the effects of a forest cover in promoting absorption of rainfall and controlling erosion. But a study of grass as a stabilizer of lands and a means of increasing absorption and diminishing runoff has just begun. It has resulted from the present physical crisis in land use within the United States and especially in the west. This crisis is a consequence of the period of exploitation resulting from the rapid occupation of the whole country by a civilized people. The story of American agriculture has been one of breaking new soil, farming it hard, and then, when yields began to fall off, moving west to repeat the cycle. The time has gone, however, when worn out lands can be abandoned for virgin soils, with their stored fertility, and undepleted ranges lying to the west. These changes have occurred rapidly. As stated by Lowdermilk (\u2735a ): Soils which had been thoroughly protected through thousands of years of time by unbroken mantles of vegetation, and, for this reason, had weathered to fine textures with high organic contents so favorable to \u27mellowness\u27 and good fertility, were suddenly exposed to the dash of torrential rains characterizing the climate of extensive regions. . .. Topsoils have been literally washed away, leaving raw, comparatively unproductive, unabsorptive, intractible subsoil exposed at the surface ..... of the greater part of the crop and grazing areas of the West. The natural cover of prairie vegetation has nearly all been removed by breaking, or sorely depleted by continued overgrazing. This effective preventive of erosion has been replaced by poorly sodded pastures and lands covered only temporarily with crops. Overgrazing on the one hand and cultural practices on the other have exposed much of the surface of both to the destructive action of rain and runoff waters. With a widespread erosion control campaign going on throughout the United States with the object of the best type of soil conservation, it is peculiarly desirable to take full account of the influence of plant cover. Moreover, in examining the effects of disturbances wrought by man, his implements and machines, and his domestic animals, it is desirable to begin investigations with undisturbed natural condition of the land. Fortunately many limited areas of natural grassland, especially prairies kept for the production of hay, remain to facilitate such comparative studies

    Skycorr: A general tool for spectroscopic sky subtraction

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    Airglow emission lines, which dominate the optical-to-near-IR sky radiation, show strong, line-dependent variability on various time scales. Therefore, the subtraction of the sky background in the affected wavelength regime becomes a problem if plain sky spectra have to be taken at a different time as the astronomical data. A solution of this issue is the physically motivated scaling of the airglow lines in the plain sky data to fit the sky lines in the object spectrum. We have developed a corresponding instrument-independent approach based on one-dimensional spectra. Our code skycorr separates sky lines and sky/object continuum by an iterative approach involving a line finder and airglow line data. The sky lines are grouped according to their expected variability. The line groups in the sky data are then scaled to fit the sky in the science data. Required pixel-specific weights for overlapping groups are taken from a comprehensive airglow model. Deviations in the wavelength calibration are corrected by fitting Chebyshev polynomials and rebinning via asymmetric damped sinc kernels. The scaled sky lines and the sky continuum are subtracted separately. VLT X-Shooter data covering time intervals from two minutes to about one year were selected to illustrate the performance. Except for short time intervals of a few minutes, the sky line residuals were several times weaker than for sky subtraction without fitting. Further tests show that skycorr performs consistently better than the method of Davies (2007) developed for VLT SINFONI data.Comment: 17 pages, 18 figures, accepted for publication in A&

    Puromycin Sensitivity of Ribosomal Label after Incorporation of 14C-Labelled Amino Acids into Isolated Mitochondria from Neurospora crassa

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    Radioactive amino acids were incorporated into isolated mitochondria from Neurospora crassa. Then the mitochondrial ribosomes were isolated and submitted to density gradient centrifugation. A preferential labelling of polysomes was observed. However, when the mitochondrial suspension was treated with puromycin after amino acid incorporation, no radioactivity could be detected in either the monosomes or the polysomes. The conclusion is drawn that isolated mitochondria under these conditions do not incorporate significant amounts of amino acids into proteins of their ribosomes

    Adherence and Tolerability of Alzheimer's Disease Medications: A Pragmatic Randomized Trial

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    BACKGROUND/OBJECTIVES: Post-marketing comparative trials describe medication use patterns in diverse, real-world populations. Our objective was to determine if differences in rates of adherence and tolerability exist among new users to acetylcholinesterase inhibitors (AChEI's). DESIGN: Pragmatic randomized, open label comparative trial of AChEI's currently available in the United States. SETTING: Four memory care practices within four healthcare systems in the greater Indianapolis area. PARTICIPANTS: Eligibility criteria included older adults with a diagnosis of possible or probable Alzheimer's disease (AD) who were initiating treatment with an AChEI. Participants were required to have a caregiver to complete assessments, access to a telephone, and be able to understand English. Exclusion criteria consisted of a prior severe adverse event from AChEIs. INTERVENTION: Participants were randomized to one of three AChEIs in a 1:1:1 ratio and followed for 18 weeks. MEASUREMENTS: Caregiver-reported adherence, defined as taking or not taking study medication, and caregiver-reported adverse events, defined as the presence of an adverse event. RESULTS: 196 participants were included with 74.0% female, 30.6% African Americans, and 72.9% who completed at least twelfth grade. Discontinuation rates after 18 weeks were 38.8% for donepezil, 53.0% for galantamine, and 58.7% for rivastigmine (P = .063) in the intent to treat analysis. Adverse events and cost explained 73.1% and 25.4% of discontinuation. No participants discontinued donepezil due to cost. Adverse events were reported by 81.2% of all participants; no between-group differences in total adverse events were statistically significant. CONCLUSIONS: This pragmatic comparative trial showed high rates of adverse events and cost-related non-adherence with AChEIs. Interventions improving adherence and persistence to AChEIs may improve AD management. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01362686 (https://clinicaltrials.gov/ct2/show/NCT01362686)

    Quantitative comparison of performance analysis techniques for modular and generic network-on-chip

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    NoC-specific parameters feature a huge impact on performance and implementation costs of NoC. Hence, performance and cost evaluation of these parameter-dependent NoC is crucial in different design-stages but the requirements on performance analysis differ from stage to stage. In an early design-stage an analysis technique featuring reduced complexity and limited accuracy can be applied, whereas in subsequent design-stages more accurate techniques are required. <br><br> In this work several performance analysis techniques at different levels of abstraction are presented and quantitatively compared. These techniques include a static performance analysis using timing-models, a Colored Petri Net-based approach, VHDL- and SystemC-based simulators and an FPGA-based emulator. Conducting NoC-experiments with NoC-sizes from 9 to 36 functional units and various traffic patterns, characteristics of these experiments concerning accuracy, complexity and effort are derived. <br><br> The performance analysis techniques discussed here are quantitatively evaluated and finally assigned to the appropriate design-stages in an automated NoC-design-flow

    Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments

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    Context: The interaction of the light from astronomical objects with the constituents of the Earth's atmosphere leads to the formation of telluric absorption lines in ground-based collected spectra. Correcting for these lines, mostly affecting the red and infrared region of the spectrum, usually relies on observations of specific stars obtained close in time and airmass to the science targets, therefore using precious observing time. Aims: We present molecfit, a tool for correcting for telluric absorption lines based on synthetic modelling of the Earth's atmospheric transmission. Molecfit is versatile and can be used with data obtained with various ground-based telescopes and instruments. Methods: Molecfit combines a publicly available radiative transfer code, a molecular line database, atmospheric profiles, and various kernels to model the instrument line spread function. The atmospheric profiles are created by merging a standard atmospheric profile representative of a given observatory's climate, of local meteorological data, and of dynamically retrieved altitude profiles for temperature, pressure, and humidity. We discuss the various ingredients of the method, its applicability, and its limitations. We also show examples of telluric line correction on spectra obtained with a suite of ESO Very Large Telescope (VLT) instruments. Results: Compared to previous similar tools, molecfit takes the best results for temperature, pressure, and humidity in the atmosphere above the observatory into account. As a result, the standard deviation of the residuals after correction of unsaturated telluric lines is frequently better than 2% of the continuum. Conclusion: Molecfit is able to accurately model and correct for telluric lines over a broad range of wavelengths and spectral resolutions. (Abridged)Comment: 18 pages, 13 figures, 5 tables, accepted for publication in Astronomy and Astrophysic

    Inhabiting warm microhabitats and risk-spreading as strategies for survival of a phytophagous insect living in common pastures in the Pyrenees

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    [EN] The breakdown of the transhumant grazing system in the Spanish Pyrenees has led to a severe decline in the area of pastures. However, in the high mountain zone there are still large areas of species-rich grasslands. The aim of this study was to assess the oviposition preferences of the shrub-feeding Blue-spot hairstreak, Satyrium spini (Denis & SchiffermÃller, 1775), in montane common pastures in the Spanish Pyrenees and recommend a way of managing these grasslands that favours this species. Our study showed that females of S. spini laid their eggs on Dwarf buckthorn (Rhamnus pumila Turra) and Alpine buckthorn (R. alpina L.), which are novel host plant records for Spain. A warm microclimate was of crucial importance for egg-laying. Occupied plants grew mostly at sparsely vegetated grassland sites where there were large patches of bare rocks, stones or gravel. Most egg batches were laid close to the ground and 75% consisted of only one egg. The number of batches per R. pumila plant was higher on east-, southand west-facing slopes than on north-facing slopes. Presence of eggs and the number of egg batches per R. pumila plant were best explained by a long sunshine duration. At high altitudes particularly warm microhabitats seem to be more important for S. spini than at lower altitudes in Central Europe. We assume that the preference for unusually warm microhabitats is explained by the cold climatic conditions near the altitudinal range limit of the species. That most of the eggs were laid singly and not in small batches as in Central Europe might be a risk-spreading strategy to cope with the harsh climatic conditions and the high inter-annual variation in weather conditions in the high mountain zone in the Pyrenees. The best way to maintain open grasslands for S. spini and other thermophilous grassland species in the high mountain zone of the Pyrenees is to use the traditional combination of sheep and cattle grazing.Peer Reviewe

    Magnetic field perturbation of neural recording and stimulating microelectrodes

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    To improve the overall temporal and spatial resolution of brain mapping techniques, in animal models, some attempts have been reported to join electrophysiological methods with functional magnetic resonance imaging (fMRI). However, little attention has been paid to the image artefacts produced by the microelectrodes that compromise the anatomical or functional information of those studies. This work presents a group of simulations and MR images that show the limitations of wire microelectrodes and the potential advantages of silicon technology, in terms of image quality, in MRI environments. Magnetic field perturbations are calculated using a Fourier-based method for platinum (Pt) and tungsten (W) microwires as well as two different silicon technologies. We conclude that image artefacts produced by microelectrodes are highly dependent not only on the magnetic susceptibility of the materials used but also on the size, shape and orientation of the electrodes with respect to the main magnetic field. In addition silicon microelectrodes present better MRI characteristics than metallic microelectrodes. However, metallization layers added to silicon materials can adversely affect the quality of MR images. Therefore only those silicon microelectrodes that minimize the amount of metallic material can be considered MR-compatible and therefore suitable for possible simultaneous fMRI and electrophysiological studies. High resolution gradient echo images acquired at 2 T (TR/TE = 100/15 ms, voxel size = 100 × 100 × 100 µm3) of platinum–iridium (Pt–Ir, 90%–10%) and tungsten microwires show a complete signal loss that covers a volume significantly larger than the actual volume occupied by the microelectrodes: roughly 400 times larger for Pt–Ir and 180 for W, at the tip of the microelectrodes. Similar MR images of a single-shank silicon microelectrode only produce a partial volume effect on the voxels occupied by the probe with less than 50% of signal loss.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58101/2/pmb7_8_003.pd

    Not in my back yard! Sports stadia location and the property market

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    In recent years sports stadia have been built in the UK, not only for their intended sporting purpose but with the twin aim of stimulating economic and physical regeneration. However, proposals to locate stadia in urban areas often prompt a negative reaction from local communities, fearing a decline in property prices. This paper will use a case study of the Millennium Stadium in Cardiff and the City of Manchester Stadium to illustrate that in contrast to this widely held belief, sports stadia can actually enhance the value of residential property. Furthermore, it will argue that stadia also contribute indirectly to property value through the creation of pride, confidence and enhanced image of an area.</p
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