60,268 research outputs found

    Role of Plasma Surface Treatments on Wetting and Adhesion

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    There are many current and emerging wetting and adhesion issues which require an additional surface processing to enhance interfacial surface properties. Materials which are non-polar, such as polymers, have low surface energy and therefore typically require surface treatment to promote wetting of inks and coating. One way of increasing surface energy and reactivity is to bombard a polymer surface with atmospheric plasma. When the ionized gas is discharged on the polymer, effects of ablation, crosslinking and activation are produced on its surface. In this paper we will analyse the role of plasma and its use in increasing the surface energy to achieve wettability and improve adhesion of polymeric surface

    Two New Species of Leafblight Fungi on Kalmia Latifolia

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    The evergreen shrub, Kalmia latifolia L., commonly known as mountain laurel, calico bush, or sheep-kill, grows widely on rocky, acid soils in the eastern United States. Whether growing in its natural habit or in cultivation, mountain laurel appears to be equally subject to attack by fungi. The following account characterizes and discusses two of these fungi. One of them has not been described previously and additional observations have been made regarding the developmental morphology of the other one. Both pathogens are Pyrenomycetes, one a Physalospora and the other a Diaporthe. Each produces a leafblight disease. Tiny brown discolorations on young leaves characterize the early stages of attack by both organisms. These small lesions gradually enlarge and become irregular brown spots that may encompass the major portion of the leaf surface. The invaded tissues are darkest near the margins of the lesions, but a reddish zone lies between the darker border and the surrounding green tissues. Severely attacked leaves are deformed and shed prematurely. The reproductive structures of the Physalospora occur on the lower surface and begin to develop before the leaves are shed. The pycnidial stromata of the Diaporthe elevate the epidermis and caticle, and consequently produce grayish spots on the leaf surface. Both fungi continue to develop after the leaves have fallen, and since the mycelia extend beyond the margins of the lesions, perithecia ultimately may occupy most of the leaf surface. [excerpt

    Study plasma interactions in the auroral ionosphere

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    Analyzed data from rocket flight, 29.007UE is presented. In a discrete electron arc the measured upward moving electrons are well accounted for by secondaries produced in collisional scattering of the measured downcoming electrons. No collective mechanisms need to invoke. The low energy downcoming electrons are accounted for by thermal plasma accelerated through a potential drop of a few kV that specularly reflects upward-moving lower energy electrons. No low altitude collective effects need to invoke in the arc. Simultaneous measurements of electric field by double probes on 29.007 and the Chatanika Radar allow one to infer that there are upward drifting ions above the discrete electron arc, and there is a westward neutral wind in the discrete arc. Two rocket payloads were built to investigate plasma effects in the pulsating aurora

    Estimating Functions of Probability Distributions from a Finite Set of Samples, Part 1: Bayes Estimators and the Shannon Entropy

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    We present estimators for entropy and other functions of a discrete probability distribution when the data is a finite sample drawn from that probability distribution. In particular, for the case when the probability distribution is a joint distribution, we present finite sample estimators for the mutual information, covariance, and chi-squared functions of that probability distribution.Comment: uuencoded compressed tarfile, submitte

    A theoretical study of the propagation and attenuation of acoustic waves in the lunar surface Interim report

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    Acoustic wave propagation and attenuation in lunar space environmen

    Comparison of three estimators in a polynomial regression with measurement errors

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    In a polynomial regression with measurement errors in the covariate, which is supposed to be normally distributed, one has (at least) three ways to estimate the unknown regression parameters: one can apply ordinary least squares (OLS) to the model without regard of the measurement error or one can correct for the measurement error, either by correcting the estimating equation (ALS) or by correcting the mean and variance functions of the dependent variable, which is done by conditioning on the observable, error ridden, counter part of the covariate (SLS). While OLS is biased the other two estimators are consistent. Their asymptotic covariance matrices can be compared to each other, in particular for the case of a small measurement error variance

    The location of the UK cotton textiles industry in 1838 : a quantitative analysis

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    We examine the geography of cotton textiles in Britain in 1838 to test claims about why the industry came to be so heavily concentrated in Lancashire. Our analysis considers both first and second nature aspects of geography including the availability of water power, humidity, coal prices, market access and sunk costs. We show that some of these characteristics have substantial explanatory power. Moreover, we exploit the change from water to steam power to show that the persistent effect of first nature characteristics on industry location can be explained by a combination of sunk costs and agglomeration effects

    Magnetic fields in circumstellar disks: The potential of Zeeman observations

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    Context. Recent high angular resolution polarimetric continuum observations of circumstellar disks provide new insights into their magnetic field. However, direct constraints are limited to the plane of sky component of the magnetic field. Observations of Zeeman split spectral lines are a potential approach to enhance these insights by providing complementary information. Aims. We investigate which constraints for magnetic fields in circumstellar disks can be obtained from Zeeman observations of the 113 GHz113~\mathrm{GHz} CN lines. Furthermore, we analyze the requirements to perform these observations and their dependence on selected quantities. Methods. We simulate the Zeeman splitting with the radiative transfer (RT) code POLARIS (Reissl et al. 2016) extended by our Zeeman splitting RT extension ZRAD (Brauer et al. 2017), which is based on the line RT code Mol3D (Ober et al. 2015). Results. We find that Zeeman observations of the 113 GHz113~\mathrm{GHz} CN lines provide significant insights into the magnetic field of circumstellar disks. However, with the capabilities of recent and upcoming instrument/observatories, even spatially unresolved observations would be challenging. Nevertheless, these observations are feasible for the most massive disks with a strong magnetic field and high abundance of CN/H. The most restrictive quantity is the magnetic field strength, which should be at least in the order of 1 mG\sim1~\mathrm{mG}. In addition, the inclination of the disk should be around 60deg60\deg to preserve the ability to derive the line-of-sight (LOS) magnetic field strength and to obtain a sufficiently high circularly polarized flux.Comment: 15 pages, 14 figure