463 research outputs found

    Recognizing and Managing Common Crop Disease in South Dakota

    Get PDF
    Diseases of plants may be expressed differently under varying environmental conditions or in various host species. Disease is the outward expression of an infection, yet in some cases there may be no outward evidence of disease. Outward expression may be some deviation from normal growth, change in appearance, or alteration of the quality or value of the crop. Plant diseases may be caused by biotic agents, infectious microorganisms, or abiotic causes such as chemical deposition, nutrient imbalances, or environmental factors. This publication concentrates on biotic or infectious diseases and provides information on common abiotic problems. Infectious plant diseases may be caused by fungi, bacteria, viruses, nematodes, or phytoplasmas. Each of these microorganisms has characteristics that can be keyed on in the control or management process. The most common cause of plant diseases are fungi. Outward indications may be present that indicate there is something wrong with a plant. Most often you observe symptoms of a disease—the reaction of the plant to a pathogen. Symptoms are defined as any perceptible change in host structure or function that indicates disease or disorder. Slimy, dark, roots; lodging; holes in the leaves; and blasted heads are all examples of symptoms. The pathogen that is causing the disease may or may not be visible. Sometimes the pathogen can also be seen. When the pathogen or a structure of the pathogen is present it is referred to as a sign. Signs may appear as an ooze, a cottony mass, or sometimes a black or pink mass on the plant. Some types of bacteria, fungi, nematodes, and viruses cause plant diseases. Weather and unfavorable growing conditions may interact with the pathogen to increase or decrease severity of the problem. The diseases listed here are historically found in South Dakota. Depending on the crop varieties planted or currently prevalent forms of the pathogens, diseases may become more or less important over the years. Occurrence of the diseases listed is reported as widespread, common, fairly common, or rare in South Dakota. The symptoms of each disease are described and the period when the disease is most common is provided for each crop. Be sure to monitor fields between the dates given for the presence of specific diseases

    HIV related isolated tuberculosis of the spleen: A case report

    Get PDF
    A patient with left upper quadrant pain, intermittent fever, and weight loss but no radiographic evidence suggestive of pulmonary tuberculosis is presented. Abdominal sonography showed multiple hypo echoic nodular splenic lesions reported as foci of infection/abscess. Histopathology study of splenectomy specimen revealed caseous tuberculous lesions of near normal size organ

    Evaluation of the shortwave cloud radiative effect over the ocean by use of ship and satellite observations

    Get PDF
    In this study the shortwave cloud radiative effect (SWCRE) over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements. The ship observations yield cloud fraction, liquid water path from a microwave radiometer, cloud bottom height as well as temperature and humidity profiles from radiosonde ascents. Level-2 products of the Satellite Application Facility on Climate Monitoring (CM~SAF) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) have been used to characterize clouds. Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR) and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations. Four of these experiments are defined to investigate the advantage of including the satellite-based cloud droplet effective radius as additional cloud property. The modeled SWCRE based on satellite retrieved cloud properties has a comparable accuracy to the modeled SWCRE based on ship data. For several cases, an improvement through introducing the satellite-based estimate of effective radius as additional information to the ship based data was found. Due to their different measuring characteristics, however, each dataset shows best results for different atmospheric conditions

    Direct strain and elastic energy evaluation in rolled-up semiconductor tubes by x-ray micro-diffraction

    Full text link
    We depict the use of x-ray diffraction as a tool to directly probe the strain status in rolled-up semiconductor tubes. By employing continuum elasticity theory and a simple model we are able to simulate quantitatively the strain relaxation in perfect crystalline III-V semiconductor bi- and multilayers as well as in rolled-up layers with dislocations. The reduction in the local elastic energy is evaluated for each case. Limitations of the technique and theoretical model are discussed in detail.Comment: 32 pages (single column), 9 figures, 39 reference

    Structural and magnetic properties of an InGaAs/Fe3_3Si superlattice in cylindrical geometry

    Full text link
    The structure and the magnetic properties of an InGaAs/Fe3Si superlattice in a cylindrical geometry are investigated by electron microscopy techniques, x-ray diffraction and magnetometry. To form a radial superlattice, a pseudomorphic InGaAs/Fe3As bilayer has been released from its substrate self-forming into a rolled-up microtube. Oxide-free interfaces as well as areas of crystalline bonding are observed and an overall lattice mismatch between succeeding layers is determined. The cylindrical symmetry of the final radial superlattice shows a significant effect on the magnetization behavior of the rolled-up layers

    Effect of ribosome shielding on mRNA stability

    No full text

    Complex Degradation Processes Lead to Non-Exponential Decay Patterns and Age-Dependent Decay Rates of Messenger RNA

    Get PDF
    Experimental studies on mRNA stability have established several, qualitatively distinct decay patterns for the amount of mRNA within the living cell. Furthermore, a variety of different and complex biochemical pathways for mRNA degradation have been identified. The central aim of this paper is to bring together both the experimental evidence about the decay patterns and the biochemical knowledge about the multi-step nature of mRNA degradation in a coherent mathematical theory. We first introduce a mathematical relationship between the mRNA decay pattern and the lifetime distribution of individual mRNA molecules. This relationship reveals that the mRNA decay patterns at steady state expression level must obey a general convexity condition, which applies to any degradation mechanism. Next, we develop a theory, formulated as a Markov chain model, that recapitulates some aspects of the multi-step nature of mRNA degradation. We apply our theory to experimental data for yeast and explicitly derive the lifetime distribution of the corresponding mRNAs. Thereby, we show how to extract single-molecule properties of an mRNA, such as the age-dependent decay rate and the residual lifetime. Finally, we analyze the decay patterns of the whole translatome of yeast cells and show that yeast mRNAs can be grouped into three broad classes that exhibit three distinct decay patterns. This paper provides both a method to accurately analyze non-exponential mRNA decay patterns and a tool to validate different models of degradation using decay data

    Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

    Get PDF
    <p>Abstract</p> <p>The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The &#8220;etch suppression&#8221; area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.</p
    • …
    corecore