15,028 research outputs found

    A study of the break-up characteristics of Chena River Basin using ERTS imagery

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    The author has identified the following significant results. The Chena River Basin was selected because of the availability of ground truth data for comparison. Very good agreement for snow distribution and rates of ablation was found between the ERTS-1 imagery, the snowmelt model, and field measurements. Monitoring snowmelt rates for relatively small basins appears to be practical. The main limitation of the ERTS-1 imagery is the interval of coverage. More frequent overflights providing coverage are needed for the study of transient hydrologic events. ERTS-1 data is most useful when used in conjunction with snowmelt prediction models and existing snow course data. These results should prove very useful in preliminary assessment of hydrologic conditions in ungaged watersheds and will provide a tool for month-to-month volume forecasting

    Break-up characteristics of the Chena River watershed, central Alaska

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    The author has identified the following significant results. The snow melt for a small watershed (5130 sq km) in Central Alaska was successfully monitored with ERTS-1 imagery. Aerial photography was used as supporting data for periods without satellite coverage. Comparison both with actual measurements and with a computer model showed good agreement

    Effective Widths and Effective Number of Phonons of Multiphonon Giant Resonances

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    We discuss the origin of the difference between the harmonic value of the width of the multiphonon giant resonances and the smaller observed value. Analytical expressions are derived for both the effective width and the average cross-section. The contribution of the Brink-Axel mechanism in resolving the discrepancy is pointed out.Comment: 9 pages, 4 figure

    Controlling Internal Parasites of Sheep

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    Parasitism is the worst hazard in the raising of sheep. This is true in South Dakota and is generally true in other sheep-raising areas. No accurate figure of the cost of worm infestations can be given. The cost includes the loss in deaths, the lowered values of the unthrifty, light-weight lambs which survive, the added expense in feed and time in making such lambs salable, the cost of worm treatments and time in administering them. To these costs should be added the weight loss by sheep, resulting from moving them from range for treatments, and the handling of the flock incident to treatment. If figures were available, the total annual loss to sheep growers would certainly be many thousands of dollars in South Dakota alone. There has been a marked increase in numbers of sheep in the state in the past twenty-year period, from 682,000 in 1925 to a high of 2,300,000 in 1944. An increase in numbers on some farms and ranches without corresponding increase in acreage for pasture has no doubt contributed greatly to the seriousness of the parasite problem. There was a decline of 26 per cent in numbers of sheep in the two years preceding January 1, 1946.2 Difficulty experienced in controlling internal parasites is undoubtedly one of the factors responsible for the decrease. Some flocks were reduced in numbers and some were sold, entirely because of this difficulty. A study was undertaken in 1943 with the ultimate purpose of finding means of reducing the loss from parasites.3 The work has been confined largely to the range areas of the northwestern counties. It has included field observations of flock and range management methods, examination of sheep for evidence of parasitic infestations, and postmortem examinations for the various kinds of worms. During the 1945 grazing season an experimental flock was maintained under range conditions for study of the parasite problem

    Reliable solid-state circuits Semiannual report no. 2, Jun. 1 - Nov. 30, 1965

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    Pulse width modulator and other microminiaturized electronic equipment for space age application

    The Semiclassical Coulomb Interaction

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    The semiclassical Coulomb excitation interaction is at times expressed in the Lorentz gauge in terms of the electromagnetic fields and a contribution from the scalar electric potential. We point out that the potential term can make spurious contributions to excitation cross sections, especially when the the decay of excited states is taken into account. We show that, through an appropriate gauge transformation, the excitation interaction can be expressed in terms of the electromagnetic fields alone.Comment: 12 pages. Phys. Rev. C, Rapid Communication, in pres

    Quantum Monte Carlo Calculations of A6A\leq6 Nuclei

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    The energies of 3H^{3}H, 3He^{3}He, and 4He^{4}He ground states, the 32{\frac{3}{2}}^{-} and 12{\frac{1}{2}}^{-} scattering states of 5He^{5}He, the ground states of 6He^{6}He, 6Li^{6}Li, and 6Be^{6}Be and the 3+3^{+} and 0+0^{+} excited states of 6Li^{6}Li have been accurately calculated with the Green's function Monte Carlo method using realistic models of two- and three-nucleon interactions. The splitting of the A=3A=3 isospin T=12T=\frac{1}{2} and A=6A=6 isospin T=1T=1, Jπ=0+J^{\pi} = 0^{+} multiplets is also studied. The observed energies and radii are generally well reproduced, however, some definite differences between theory and experiment can be identified.Comment: 12 pages, 1 figur

    Large N_c, Constituent Quarks, and N, Delta Charge Radii

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    We show how one may define baryon constituent quarks in a rigorous manner, given physical assumptions that hold in the large-N_c limit of QCD. This constituent picture gives rise to an operator expansion that has been used to study large-N_c baryon observables; here we apply it to the case of charge radii of the N and Delta states, using minimal dynamical assumptions. For example, one finds the relation r_p^2 - r_{Delta^+}^2 = r_n^2 - r_{Delta^0}^2 to be broken only by three-body, O(1/N_c^2) effects for any N_c.Comment: 15 pages, 1 eps figure. Version to appear in Phys. Rev.

    Roughness of Sandpile Surfaces

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    We study the surface roughness of prototype models displaying self-organized criticality (SOC) and their noncritical variants in one dimension. For SOC systems, we find that two seemingly equivalent definitions of surface roughness yields different asymptotic scaling exponents. Using approximate analytical arguments and extensive numerical studies we conclude that this ambiguity is due to the special scaling properties of the nonlinear steady state surface. We also find that there is no such ambiguity for non-SOC models, although there may be intermediate crossovers to different roughness values. Such crossovers need to be distinguished from the true asymptotic behaviour, as in the case of a noncritical disordered sandpile model studied in [10].Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev.

    Utilization of Drought-Stricken Corn Silage by Yearling Steers

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    Corn silage is a very versatile and palatable feed that fits well into many cattle feeding programs. Insufficient rainfall in several areas of the country in recent years has resulted in many additional acres of corn being ensiled due to the low potential grain yield. Harvesting drought-stricken corn silage results in at least partial salvage of the crop. However, many farmers have expressed concern about the feeding value of drought-damaged corn silage and how it can be best incorporated into feedlot rations for optimal performance and maximal economic return
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