Showing papers by "Iowa State University published in 1974"
TL;DR: Studies on a large number of model compounds added to water in the 10- to 100-ppb range (20 parts per trillion for pesticides) demonstrated that this method is accurate and reliable.
501 citations
TL;DR: In this article, sufficient conditions are presented under which the generalized least squares estimator, with estimated covariance matrix, is unbiased for the parameters in the crossed-error model and has the same asymptotic distribution as the GLS estimator.
442 citations
TL;DR: In this article, a simple and precise turbidimetric method of determining sulfate S in water samples is described, which involves measurement of the turbidity formed when an aliquot of a barium chloride-gelatin reagent is added to an acidified sample.
Abstract: A simple and precise turbidimetric method of determining sulfate S in water samples is described. It involves measurement of the turbidity formed when an aliquot of a barium chloride-gelatin reagent is added to an acidified sample. The method is sensitive and accurate and permits determination of microgram amounts of sulfate S present in water samples.
322 citations
01 Dec 1974
222 citations
TL;DR: Conception rates of a Holstein dairy herd near Culiacan on the west coast of Mexico were evaluated with respect to the average temperature-humidity index of the 2 days prior to breeding, the day of breeding, and the day following breeding indicating that temperature- Humidity of individual days before and after breeding influenced breeding efficiency.
186 citations
180 citations
01 Jan 1974
177 citations
TL;DR: Dxtran is biosynthesized by the transfer of glucose from sucrose to the reducing end of the growing dextran chain by a nucleophilic attack of the C 6 —OH of glucose onto C 1 of the dextransucrase forming an α-1 → 6 glucosidic bond.
162 citations
TL;DR: Parturient paresis was prevented by feeding a calcium-deficient diet composed of corn silage, ground shelled corn, a dried molasses product, urea, and monosodium phosphate, which supplied only 8g of calcium daily per 450kg body weight.
132 citations
TL;DR: The results support the previous conclusion that the same enzyme may act on several phosphorylated substrates in heart, and show the importance of the substrate in the regulation of the phosphoprotein phosphatase in heart tissue.
121 citations
TL;DR: In this paper, wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion, which indicated that some dark zones around Martian craters are erosional and some light zones are depositional.
Abstract: Preliminary results are reported of an investigation which involves wind tunnel simulations, geologic field studies, theoretical model studies, and analyses of Mariner 9 imagery. Threshold speed experiments were conducted for particles ranging in specific gravity from 1.3 to 11.35 and diameter from 10.2 micron to 1290 micron to verify and better define Bagnold's (1941) expressions for grain movement, particularly for low particle Reynolds numbers and to study the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some martian craters and which indicates that some dark zones around Martian craters are erosional and some light zones are depositional.
TL;DR: In this article, an approximate solution to the problem of incompressible flow through an axisymmetric constriction is presented to simulate an arterial stenosis, and the solution is applicable to both mild and severe stenoses for Reynolds numbers below transition.
TL;DR: During development the microspores and pollen grains form depressions in the tapetal orbicular wall, the microSpore pore being tightly appressed to the Tapetum until maturity.
Abstract: During development the microspores and pollen grains form depressions in the tapetal orbicular wall, the microspore pore being tightly appressed to the tapetum until maturity
TL;DR: In this article, implicit contiguity of related items whose list presentations are physically disparate results from the subject looking back through memory so as to bring the items together in mental experience was examined in three experiments by controlling looking-back behavior during list presentation and varying the separation of target items and related items that were later provided as recall cues.
01 Oct 1974
TL;DR: In this paper, simplified curve fits for the thermodynamic properties of equilibrium air were devised for use in either the time-dependent or shock-capturing computational methods, for temperatures up to 25,000 K and densities from 10 to the minus 7th power to 10 to 3d power amagats.
Abstract: Simplified curve fits for the thermodynamic properties of equilibrium air were devised for use in either the time-dependent or shock-capturing computational methods. For the time-dependent method, curve fits were developed for p = p(e, rho), a = a(e, rho), and T = T(e, rho). For the shock-capturing method, curve fits were developed for h = h(p, rho) and T = T(p, rho). The ranges of validity for these curves fits were for temperatures up to 25,000 K and densities from 10 to the minus 7th power to 10 to the 3d power amagats. These approximate curve fits are considered particularly useful when employed on advanced computers such as the Burroughs ILLIAC 4 or the CDC STAR.
TL;DR: Generally, Streptococcus thermophilus ferments sucrose, whereas Lactobacillus bulgaricus fails to utilize this disaccharide, but when both sucrose and lactose were added to a basal medium, S. thermophile fermented both carbon sources, produced sufficient acid to change the color of an acid-base indicator, and hence formed yellow colonies.
Abstract: Generally, Streptococcus thermophilus ferments sucrose, whereas Lactobacillus bulgaricus fails to utilize this disaccharide. When both sucrose and lactose were added to a basal medium, S. thermophilus fermented both carbon sources, produced sufficient acid to change the color of an acid-base indicator (bromcresol purple), and hence formed yellow colonies. On the same medium, most L. bulgaricus strains grew more slowly, produced less acid, and yielded white colonies. Acid diffusion around the S. thermophilus colonies was localized by incorporation of CaCO3 into the medium. To test the efficacy of this medium when known strains of starters are used, the effect of freezing with liquid nitrogen on mixed cultures of S. thermophilus and L. bulgaricus was studied.
TL;DR: In this paper, the inhibitory effects of these volatile sulfur compounds on nitrification decrease in the order listed, and it is concluded from the work reported that the effect of these compounds on Nitrification in soils may be at least partly due to decomposition of the compounds by soil microorganisms with formation of volatile sulfur compound that retard nitrification.
Abstract: Carbon disulfide, dimethyl disulfide, methyl mercaptan, dimethyl sulfide, and hydrogen sulfide retard nitrification of ammonium in soils incubated in closed systems. The inhibitory effects of these volatile sulfur compounds on nitrification decrease in the order listed. Hydrogen sulfide is a relatively weak inhibitor of nitrification, but carbon disulfide is considerably more effective than patented nitrification inhibitors (N-Serve. AM, and ST) for inhibition of nitrification in closed systems. It is concluded from the work reported that the inhibitory effects of methionine, cystine, cysteine, and other nonvolatile organic sulfur compounds on nitrification in soils may be at least partly due to decomposition of these compounds by soil microorganisms with formation of volatile sulfur compounds that retard nitrification.
TL;DR: Wind tunnel experiments have revealed a characteristic flow field pattern over raised-rim craters which causes distinctive zones of aeolian erosion and deposition, and comparisons with Mariner 9 images of Mars show that some crater-associated dark zones result from wind erosion and that some hole-associated light streaks are depositional.
Abstract: Wind tunnel experiments have revealed a characteristic flow field pattern over raised-rim craters which causes distinctive zones of aeolian erosion and deposition. Comparisons of the results with Mariner 9 images of Mars show that some crater-associated dark zones result from wind erosion and that some crater-associated light streaks are depositional.
TL;DR: The superconducting transition temperature of tetragonal I sodium tungsten bronze (NaxWO3) has been found to increase rapidly as the x-value is decreased to the metal-semiconductor phase transition as mentioned in this paper.
TL;DR: The genetics of cannibalism and the significance of its density-dependent mechanism in teleosts of the genus Poeciliopsis, a five-membered unisexual–bisexual complex, is examined.
Abstract: THE success of viviparous species is a result of their capacity to produce small numbers of advanced offspring with high survivorship potential. Cannibalism, which would appear to be antithetical to this adaptation, is widespread among viviparous fishes1–3. I have examined the genetics of cannibalism and the significance of its density-dependent mechanism in teleosts of the genus Poeciliopsis. A five-membered unisexual–bisexual complex has evolved in this genus through hybridisation of a cannibalistic species, Poeciliopsis monacha, with the noncannibalistic species, P. lucida. Hybridisation of these two species formed P. monacha-lucida4, a diploid unisexual; backcrosses of this diploid form with each of its progenitors resulted in the evolution of two triploid unisexuals: P. monacha-2 lucida and P. 2 monacha-lucida5. All these rely on males of the bisexual species for fertilisation.
TL;DR: The mushroom toxin, α-amanitin, was used to determine which forms of RNA polymerase are active and the relative amounts of each form which are present in preimplantation mouse embryos.
Abstract: THE effects of various metabolic inhibitors, including actinomycin D, puromycin, cycloheximide, mitomycin C, and fluorophenylalanine, on preimplantation mouse embryos have been previously studied1–6, to investigate when RNA synthesis begins in preimplantation embryos and what types of RNA are synthesised during the various stages of development. Monesi and Salfi3 originally reported that there was no appreciable overall RNA synthesis until the morula stage. Ellem and Gwatkin7 also found no detectable RNA synthesis at the two-cell stage of development. Recently, using more sensitive techniques, RNA synthesis has been detected as early as the two-cell stage of development8–10. We assumed that since RNA synthesis occurs in preimplantation mouse embryos, the enzyme, DNA-dependent RNA polymerase, must be active. We report here the results of in vivo and in vitro experiments intended to characterise more fully the RNA polymerase present in preimplantation mouse embryos. We used the mushroom toxin, α-amanitin, to determine which forms of RNA polymerase are active and the relative amounts of each form which are present in preimplantation mouse embryos.
TL;DR: On the basis of field observations and a laboratory feeding experiment, the resin seems to function mainly as an insect repellent and may also reduce water loss from young leaves.
Abstract: When buds form in summer or early fall, modified stipules act as bud scales and their adaxial epidermis secretes a resin that fills the bud. This secretory layer collapses in the dormant bud. Immature leaves, stipules, and leaf primordia occupy the center of the bud; all lack functional resin glands. In spring, stipules of emerging leaves develop an adaxial palisadelike secretory epidermis that becomes more ridged longitudinally in successive stipules. Marginal teeth of the first leaves to emerge are covered with trichomes and lack a secretory epidermis. In successive leaves the teeth become glandular and secrete resin as the lamina unrolls. Later in the season, marginal leaf glands account for much of the resin. Unspecialized hydathodes or extrafloral nectaries occur proximal to each glandular tip. Guttation of water or nectar occurs here through stomata located above a vein ending. On the basis of field observations and a laboratory feeding experiment, the resin seems to function mainly as an insect repellent. It may also reduce water loss from young leaves.
TL;DR: In this paper, the authors made measurements on thin semitransparent films of Ag at about 320, 120, and 15 K in the range 3.40-4.40 eV and showed that thin metal films evaporated on amorphous substrates become strained upon cooling to low temperature.
Abstract: Thermoreflection and thermotransmission measurements were made on thin semitransparent films of Ag at about 320, 120, and 15 K in the range 3.40-4.40 eV. The results are in fairly good agreement with the theory presented in the preceding paper but show that thin metal films evaporated on amorphous substrates become strained upon cooling to low temperature. The onset of the ${L}_{3}\ensuremath{\rightarrow}L_{2}^{\ensuremath{'}}({E}_{F})$ transition is found to be at 4.03 eV, while the onset of the $L_{2}^{\ensuremath{'}}({E}_{F})\ensuremath{\rightarrow}{L}_{1}$ transition occurs at 3.87 eV.
TL;DR: Ulastructural studies revealed schizonts containing 4 merozoites and macrogametes andSchizonts with characteristic attachment zones and double membranes in the large intestinal mucosa of a domestic goose from Iowa, where the only lesion associated with infection was shortening of the intestinal microvilli.
Abstract: SYNOPSIS. Cryptosporidium anserinum sp. n. is described in the large intestinal mucosa of a domestic goose, Anser anser L., from Iowa. Ultrastructural studies revealed schizonts containing 4 merozoites and macrogametes and schizonts with characteristic attachment zones and double membranes. The only lesion associated with infection was shortening of the intestinal microvilli.
TL;DR: In this article, an error-in-variables procedure is presented that provides estimators of the coefficients and their variances in a linear model with measurement error in the independent variables.
Abstract: A linear model with measurement error in the independent variables is considered. An errors-in-variables procedure is presented that provides estimators of the coefficients and their variances. If the dependent variable has multiple measures, the total variance of the dependent variable can be decomposed into measurement error, variance of true values explained by the true values of the independent variables and variance of true values not explained by the model. An application to the measurement of role performance is presented.
TL;DR: Fifteen species of freshwater blue-green algae, including unicellular, filamentous, and colonial forms, were subjected to a variety of fixatives, fixation conditions, and stains for comparison of the preservation of phycobilisomes, strenghening the hypothesis that phy cobiliproteins are common to all phYcobiliprotein-containing photosynthetic blue- green algae.
Abstract: Fifteen species of freshwater blue-green algae, including unicellular, filamentous, and colonial forms, were subjected to a variety of fixatives, fixation conditions, and stains for comparison of the preservation of phycobilisomes. Absorption spectra of the corresponding in vivo and released photosynthetic pigments, in 10 of the species that were maintained in culture, demonstrated the presence of phycocyanin in all 10 species and phycoerythrin in only 2 of them. Spectroscope and electron microscope evidence was obtained for localization of phycobiliproteins in phycobilisomes of Nostoc muscorum. Phycobilisomes were observed in all species examined in situ, strenghening the hypothesis that phycobilisomes are common to all phycobiliprotein-containing photosynthetic blue-green algae.