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Showing papers by "Oklahoma State University–Stillwater published in 1985"


Book
01 Jan 1985
TL;DR: In this paper, theoretical background and additional factors governing thermoluminescence are discussed. But the authors focus on the geology applications and do not address the effect of temperature variations on the properties of the thermoluminant.
Abstract: Preface 1. Introduction 2. Theoretical background 3. Thermoluminescence analysis 4. Additional factors governing thermoluminescence 5. Defects and thermolumienscence 6. Thermoluminescence dosimetry (TLD) 7. Thermoluminescence dating 8. Geological applications 9. Instrumentation Appendices References Index.

1,388 citations


Book
01 Jan 1985
TL;DR: In this article, the authors present the papers given at a workshop on wind turbines, including aerodynamics, load conditions, Darrieus rotors, composite materials, turbine blades, fabrication, fiberglass, vibrations, wind power plants, control systems, data acquisition systems, performance testing, horizontal axis turbines, vertical axis turbines.
Abstract: This book presents the papers given at a workshop on wind turbines. Topics considered at the workshop included aerodynamics, load conditions, Darrieus rotors, composite materials, turbine blades, fabrication, fiberglass, vibrations, wind power plants, control systems, data acquisition systems, performance testing, horizontal axis turbines, vertical axis turbines, tornado turbines, electric generators, and wind turbine arrays.

610 citations


Journal ArticleDOI
TL;DR: In this article, a one-dimensional transient thermal model with an nth order ap proximation for the rate of decomposition of a polymer composite material undergoing decomposition was applied.
Abstract: The thermal response of a polymer composite material undergoing decomposition has been modeled. A one-dimensional transient thermal model with an nth order ap proximation for the rate of decomposition was applied. The model was tested by ex perimentally measuring the temperature profiles during decomposition for a glass- filled phenol-formaldehyde polymer composite. Additionally, the specific heat and thermal conductivity of the virgin and char components, heat of decomposition, and the kinetic parameters were experimentally determined and used as input to the model. The predicted temperature profiles are in good agreement with experimental temperatures obtained using a radiant heat flux apparatus.

266 citations


Journal ArticleDOI
TL;DR: Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalotes and weight gain depressions attributed to thermostresses can be partially alleviated dietarily.

230 citations


Journal ArticleDOI
TL;DR: In this article, Biggadike et al. found that corporate level managers can act upon managers of portfolios of business to influence CV performance, as well as numerous other findings that lower-level managers can use to strategically position their operations better.

198 citations


Journal ArticleDOI
TL;DR: In this paper, a Landau theory is presented and discussed in terms of the results of a two-dimensional colloidal liquid of strongly interacting spherical particles to produce an external periodic potential and stimulate a density modulation.
Abstract: Laser beams are crossed in a two-dimensional colloidal liquid of strongly interacting spherical particles to produce an external periodic potential and stimulate a density modulation. If the modulation wave vector is at the peak in the static structure factor, a sufficiently large potential induces a phase transition to a structure which exhibits solidlike order having density modes other than those directly excited. A Landau theory is presented and discussed in terms of our results.

169 citations


Journal ArticleDOI
TL;DR: In this paper, a model of professionalization based largely on the power view is presented, and professional power is defined in terms of two dimensions of attitudinal autonomy: autonomy from client and autonomy from employing organization.
Abstract: A model of professionalization based largely on the power view is presented. As a test of a portion of the model, professional power is defined in terms of two dimensions of attitudinal autonomy. Autonomy from client and autonomy from employing organization are studied in a sample of 1,000 students representing eight different occupations (medicine, law, education, nursing, social work, librarianship, engineering, and business administration) in order to discover a systematic empirical referent for the concepts true, semi-, and mimic profession. As hypothesized, distinct attitudinal power profiles did emerge as characteristic of individuals socialized to various occupations.

168 citations



Journal ArticleDOI
TL;DR: In this paper, optical absorption and emission spectra for Pr 3+ ions in fluorozirconate (ZBLA) glass are compared with calculated values, and Radiative transition rates for the excited states are determined by using the Judd-Ofelt theory.
Abstract: Optical absorption and emission spectra are presented for Pr 3+ ions in fluorozirconate (ZBLA) glass. The measured oscillator strengths and radiative rates for several transitions are compared with calculated values. Radiative transition rates for the excited states are determined by using the Judd-Ofelt theory. Energy transfer effects account for the nonradiative transitions. Although the Judd-Ofelt analysis does not yield the same excellent consistency for oscillator strengths and branching ratios for Pr 3+ as for Er 3+ and Ho 3+ , the experimental observations are consistent with the Judd-Ofelt calculations and the multiphonon emission rates predicted by the phenomenological energy-gap law. The crystallization of ZBLA glass also was studied, using Pr 3+ ions as probes.

139 citations


Journal ArticleDOI
TL;DR: Embryo-lethal mutants of Arabidopsis thaliana were isolated by treating mature seeds with an aqueous solution of ethyl methanesulfonate, screening the resulting M-1 plants for siliques containing 25% aborted seeds following self-pollination, and verifying the presence of induced mutations in subsequent generations.
Abstract: Embryo-lethal mutants of Arabidopsis thaliana were isolated by treating mature seeds with an aqueous solution of ethyl methanesulfonate (EMS), screening the resulting M-1 plants for siliques containing 25% aborted seeds following self-pollination, and verifying the presence of induced mutations in subsequent generations. Thirty-two recessive lethals with a Mendelian pattern of inheritance were examined in detail. Developmental arrest of mutant embryos ranged from the zygotic stage of embryogenesis in mutant 53D-4A to the linear and curled cotyledon stages of development in mutants 112A-2A and 130B-A-2. These lethal phases did not change significantly when plants were grown at 18 °C rather than at 24 °C. Differences between mutant lines were found in the color of arrested embryos and aborted seeds, the percentage and distribution of aborted seeds in heterozygous siliques, the size of arrested embryos, and the extent of abnormal development. Unusual mutant phenotypes included the presence of unusually large suspensors, distorted and fused cotyledons, reduced hypocotyls, and arrested embryos without distinct cotyledons or hypocotyl tissue. The isolation of eight new mutants with a non-random distribution of aborted seeds in heterozygous siliques provides further evidence that many of the genes that control early stages of embryogenesis in plants are also expressed prior to fertilization.

138 citations


Journal ArticleDOI
26 Jul 1985-Science
TL;DR: Genetic diversity in remnant populations of the Sonoran topminnow Poeciliopsis occidentalis from Arizona is compared with that in populations from Sonora, Mexico, where the fish is widespread and abundant.
Abstract: Genetic diversity in remnant populations of the Sonoran topminnow Poeciliopsis occidentalis (Pisces: Poeciliidae) from Arizona, where the species is endangered, is compared with that in populations from Sonora, Mexico, where the fish is widespread and abundant. Geographically peripheral Arizona populations contain substantially lower levels of genetic variation than do Mexican populations near the center of the species9 range. Allelic differences among three genetically and geographically distinct groups are responsible for 53 percent of the total genetic diversity in this species, 26 percent is due to differences among local populations within the groups, and 21 percent is due to heterozygosity within local populations. Recommendations for conservation and restocking efforts in Arizona are based on these genetic findings.

Journal ArticleDOI
TL;DR: A scaling form for the pair correlation function of random fractals is combined with the scaling form of the percolation distribution of cluster sizes to obtain expressions for the static structure factor S(q) and first cumulant K/sub 1/ of the dynamic structure factorS(q,t) at the gel point.
Abstract: A scaling form for the pair correlation function of random fractals is combined with the scaling form of the percolation distribution of cluster sizes to obtain expressions for the static structure factor S(q) and first cumulant ${K}_{1}$ of the dynamic structure factor S(q,t) at the gel point. We find S(q)\ensuremath{\sim}${q}^{\mathrm{\ensuremath{-}}\ensuremath{\mu}}$ and ${K}_{1}$\ensuremath{\sim}${q}^{3}$ with \ensuremath{\mu}=D(3-\ensuremath{\tau}), where D is the fractal dimension and \ensuremath{\tau} is the exponent for the distribution of cluster sizes. Special forms are suggested for the scaling functions to obtain results for the nonscaling regime.

Journal ArticleDOI
TL;DR: In this article, the number of bacteria in subsurface samples has been determined by microscopic counting after acridine orange staining; the proportion of cells capable of respiration was determined by INT reduction.
Abstract: Ground-water pollution by organic compounds has become a major environmental concern. Because the transport and fate of the organic pollutants may be influenced by microorganisms present in subsurface material, reliable measurements of the number of organisms in subsurface samples and their metabolic activity are needed. A special drilling rig and aseptic procedures have been developed by the Robert S. Kerr Environmental Research Laboratory of the United States Environmental Protection Agency to yield uncontaminated subsurface samples. The number of bacteria in subsurface samples has been determined by microscopic counting after acridine orange staining; the proportion of cells capable of respiration was determined by INT reduction. An independent measure of metabolic activity was obtained by measuring ATP extracted from the samples. A procedure and extradant for the extraction of ATP from subsurface material have been developed. The extractant contains reagents to reduce the loss of the extracted ATP. Subsurface samples from Oklahoma and Texas contain 106-107 cells per g of subsurface material (depths of 2–9 m). Both methods show that usually between 1 and 10% of the cells were metabolically active. Thus, significant numbers of metabolically active bacteria exist in subsurface material with the potential to modify pollutants.

Journal ArticleDOI
TL;DR: In this paper, the optical-spectroscopic properties of alexandrite (BeAl) and O(O(O)) crystals were studied by different laser spectroscopy techniques and the temperature dependences of the fluorescence lifetimes and widths of the zero-phonon lines were found.
Abstract: Details of the optical-spectroscopic properties of alexandrite (${\mathrm{BeAl}}_{2}$${\mathrm{O}}_{4}$:${\mathrm{Cr}}^{3+}$) crystals were studied by different laser-spectroscopy techniques. The temperature dependences of the fluorescence lifetimes and widths of the zero-phonon lines were found to be quite different for ${\mathrm{Cr}}^{3+}$ ions in the mirror and inversion crystal-field sites. The results indicate that direct phonon-absorption processes dominate both thermal line broadening and lifetime quenching for ions in the mirror sites while phonon-scattering processes dominate the line broadening of inversion-site ions and leave their lifetime independent of temperature. Tunable-dye-laser site-selection methods were used to obtain the excitation spectra of the ${\mathrm{Cr}}^{3+}$ ions in inversion sites at low temperature and to identify six types of exchange-coupled pairs of ${\mathrm{Cr}}^{3+}$ ions in the lattice. Time-resolved site-selection spectroscopy was used to monitor the energy transfer between ${\mathrm{Cr}}^{3+}$ ions in mirror and inversion sites at both low and high temperature. Finally, high-power, picosecond pulse excitation was used to produce two-photon absorption, and the resulting emission spectrum was found to exhibit a new fluorescence band in the 400-nm spectral region.

Journal ArticleDOI
TL;DR: A decrease of immunoglobulin absorption may be accomplished in a variety of ways such as competition between intestinal microbes and Immunoglobulins for a common receptor on the intestinal epithelial cell.

Journal ArticleDOI
TL;DR: In this paper, LiNbO3 has been shown to have a high photoconductivity, which is related to a distinctive electronic environment for impurities in the damage-resistant crystals.
Abstract: Compositions of lithium niobate containing 4.5 at.% or more MgO have the ability to transmit, without distortion, light 100 times as intense as undopecl compositions. Holographic diffraction measurements of photorefraction have demonstrated that the improved performance is due to a hundredfold increase in the photoconductivity, rather than to a decrease in the Glass current. The damage-resistant compositions are also distinguished by a thermal activation energy of 0.1 eV for the diffraction efficiency, an OH-stretch vibration at 2.83 Am, a lattice phonon absorption at 21.2 Am, an electron spin resonance signal for Fe impurities at 1500 G, and, after reduction by heating in a vacuum, an optical absorption band at 1.2 um. (The corresponding values for undopedl LiNbO3 are 0.5 eV, 2.87 um, 21.8 um, 790 G, and 0.5 um, respectively.) The high photoconductivity is thus related to a distinctive electronic environment for impurities in the damage-resistant crystals. The photoconductivity strongly affects the impedance and time constants of signal processing devices made of LiNbO3.

Journal ArticleDOI
TL;DR: In this article, the authors developed a model of firm location and city size that arrives at theoretical conclusions that differ from those of other authors, concluding that changes in national wage levels and productivity levels create no determinate (dis)advantage for large cities relative to small ones as sites for manufacturing activity.

Journal ArticleDOI
TL;DR: In this paper, performance evaluation of salespeople is examined from an attribution perspective in a field study involving sales managers, and the authors find that the presence of an attribution bias is evident.
Abstract: Performance evaluation of salespeople is examined from an attribution perspective in a field study involving sales managers. Findings support the presence of an attribution bias. Effort significant...

Journal ArticleDOI
TL;DR: One, iterative reweighted least squares (IRLS), is discussed with an eye toward improving its computational efficiency, while the other, residual steepest descent (RSD) is considered in an attempt to improve its convergence properties.
Abstract: This paper discusses two algorithms for l_{p}, 1 \leq p \leq 2 , deconvolution. One, iterative reweighted least squares (IRLS), is discussed with an eye toward improving its computational efficiency, while the other, residual steepest descent (RSD), is considered in an attempt to improve its convergence properties. In the first case, fast Fourier transforms are used to reduce the number of computations. In the second, a new rescaling procedure which enhances RSD convergence is introduced. The lack of stability of l 1 , filters, and its implications are discussed. Simple examples are used to illustrate pertinent concepts.

Journal ArticleDOI
TL;DR: A rapid assay for determining the proportions of X- and Y-chromosome-bearing sperm in semen samples would benefit research aimed at sex ratio control through sperm separation and be of value for quality control should a separation technique be developed.
Abstract: A rapid assay for determining the proportions of X- and Y-chromosome-bearing sperm in semen samples would benefit research aimed at sex ratio control through sperm separation. It also would be of value for quality control should a separation technique be developed. Flow cytometric methods capable of measuring sperm DNA content precisely enough to resolve and quantify the X and Y populations in many mammalian species have been developed. They are effective for fresh and cryopreserved sperm of most domestic animals. Results are reported of flow cytometric analyses of bull sperm samples from seven commercial and academic sources after processing with procedures purported to separate the X and Y populations. In no case was enrichment of either sperm population observed. Breeding trials carried out by the sources of two of the sets of samples showed these procedures were ineffective in altering the sex ratio.

Journal ArticleDOI
01 Apr 1985-The Auk
TL;DR: In this article, the authors describe temporal patterns of body weight, fat, and protein content in Sandhill Cranes during spring migration and compare nutrient storage and utilization patterns among northern-nesting populations of cranes and geese.
Abstract: --Body weight, fat, and protein levels of arctic-nesting Sandhill Cranes (Grus canadensis) were measured at several locations during spring migration and on the breeding grounds. Body weights of adult males and females increased by about 34% (1,129 g) and 30% (953 g) from early March at the Platte River to late April at Last Mountain Lake, Saskatchewan; average fat content increased from about 250 to 990 g. Rates of weight gain and fat deposition among males and females averaged 25-•8 and 16-13 g/day. Body weights and fat content of cranes staging along the North Platte River followed similar patterns and usually were higher than along the Platte River during comparable periods. Fat reserves of paired cranes collected after their arrival at a major breeding ground on the Yukon-Kuskokwim Delta in western Alaska averaged about 530 g, or about 46% less than peak fat content in Saskatchewan. Patterns of weight increase and fat deposition in cranes during migration were similar to those previously described for northern-nesting geese, except that nutrient storage is not sex specific in cranes. Body protein of adult female cranes did not change significantly during spring migration (P = 0.28). Female cranes allocate less nutrients to clutch formation in proportion to body size than do northern-nesting geese. Received 6 April 1984, accepted 29 October 1984. CERTAIN waterfowl have evolved successful breeding strategies in arctic environments partly through physiological adaptations that allow nutrients stored during spring migration to be utilized during reproduction. In northern-nesting geese, for example, nearly all the nutrients required to lay and incubate a clutch are carried to the breeding grounds (Ankney and Macinnes 1978, Raveling 1979). Moreover, the ability of females to store nutrients is thought to be the primary factor regulating clutch size in several species (Ryder 1970, Raveling and Luresden 1977, Davies and Cooke 1983). Although Sandhill Cranes (Grus canadensis) also breed widely in the Arctic, the extent of nutrient storage during spring migration and the contribution of nutrient reserves to reproduction is poorly understood, prompting this investigation. In this paper, we describe temporal patterns of body weight, fat, and protein content in Sandhill Cranes during spring and compare nutrient storage and utilization patterns among northern-nesting populations of cranes and geese. STUDY AREA AND METHODS Arctic-nesting populations of the Sandhill Crane breed from the Hudson Bay region in Canada westward to western Alaska and eastern Siberia (Walkinshaw 1949). The wintering grounds of the midcontinent population are primarily in the south-central United States (Texas and New Mexico) and Mexico. Spring migration lasts about 2 months, including a 4-6-week stopover each year in the Platte or North Platte river valleys in Nebraska. Collections of Sandhill Cranes were made in the Platte River Valley, the Last Mountain Lake area of Saskatchewan, and on the Clarence Rhode National Wildlife Range (NWR) on the Yukon-Kuskokwim Delta in western Alaska. Detailed descriptions of these areas have been presented as follows: the Platte River Valley by Krapu et al. (1982, 1984), the Last Mountain Lake area by Stephen (1967), and the Yukon-Kuskokwim Delta by Mickelson (1975) and Boise (1977). Sandhill Cranes were obtained by shooting during the spring stopover'period in the Platte Valley from late February to mid-April in 1978 and 1979, at Last Mountain Lake in central Saskatchewan during late April in 1978 and 1979, and on the breeding grounds at the Clarence Rhode NWR on the Yukon-Kuskokwim Delta near Old Chevak, Alaska during May in 362 The Auk 102: 362-368. April 1985 April 1985] Crane Body Composition 363 1978 and 1979. Birds collected at the latter site were paired and territorial. Nebraska and Saskatchewan staging areas are used by the western Alaska breeding population as indicated by sightings of colormarked birds (T. C. Tacha unpubl. data). Migrant specimens were collected (usually one per flock) and taken to field laboratories where wet body weight (g), flattened wing chord (ram), tarsus length (ram), and culmen length (ram, post nares and exposed) were measured to determine subspecies following criteria in Johnson and Stewart (1973). Specimens of Greater Sandhill Cranes (G. c. tabida) and Canadian Sandhill Cranes (G. c. rowani), which breed southward from the Arctic, were excluded from these s analyses, restricting the sample to Lesser Sandhill Cranes (G. c. canadensis). Adults were distinguished from iramatures (young of the previous year) by the lack of brown feathering on the occiput (Lewis 1979). Sex and reproductive status were determined by gonadal examination. In preparation for nutrient analysis, we removed all esophageal and gizzard contents, plucked each bird, reweighed the featherless carcass to the nearest gram, and homogenized the carcass in a commercial meat grinder. Measurement of lipid content in carcasses followed standard procedures (Horwitz 1975). All analyses were on the whole-carcass homogenate. Lipid content was determined by Soxhlet extraction using petroleum ether, with duplicate analyses for each specimen. Protein determination was by the Kjeldahl method (Horwitz 1975). Crane fat levels were also determined from collections made by personnel of the Oklahoma Cooperative Wildlife Research Unit in the North Platte River Valley during March-April in 1979 and 1980, Last Mountain Lake, Saskatchewan, April 1980, and during May 1980 at Delta Junction, a temporary stopover area in eastern Alaska, and on the Yukon-Kuskokwim Delta. A detailed description of methods is presented by Iverson (1981). The extent of foraging by Sandhill Cranes during the breeding season on the Yukon-Kuskokwim Delta was determined in 1979 using methods described by Wiens et al. (1970). Crane activity was sampled at 12-s intervals between 0400 and 2300 from blinds. A total of 8.7 h (2,592 observations) and 8.2 h (2,450 observations) was obtained between arrival and the onset of incubation by adult males and females, respectively. Observations were restricted to pairs on territories and began on 5 May. Sex of paired individuals was determined from differences in unison calls (Archibald 1976). All test statistics were computed with the Statistical Analysis System (Barr et al. 1979). The slopes of linear regressions of body weight and fat on Julian date were used to estimate rates of weight gain and fat deposition. Means are presented as œ + SD (n) in the text and Table 1. RESULTS CHRONOLOGY OF MIGRATION Sandhill Cranes usually begin arriving at the Platte River in late February and the population gradually builds until reaching a peak during midto late March. Radio-tagged birds in 1978 (6) and 1979 (14) stayed an average of 26 and 32 days after radios were attached in late February and early March, respectively (Krapu unpubl. data). The population of about one-half million cranes occupy about 1,036 km 2 of valley during the day and at night roost in about 111 km of channel in the Platte and North Platte rivers (Krapu et al. 1982). The days are spent foraging and resting on grassland, alfalfa hayland, and cropland near the river (Krapu et al. 1984). Sandhill Cranes depart from the Nebraska staging areas in early to mid-April. Most leave within a few days after the first flocks initiate migration. Following their stay in the Platte Valley, the birds continue northward, stopping only briefly until reaching the prairie pothole country of Saskatchewan and eastern Alberta. Upon arrival in prairie Canada, the birds roost primarily in natural basin wetlands and forage on nearby agricultural lands. In late April and early May, the cranes depart for northern breeding grounds including the Yukon-Kuskokwim Delta where they arrive from early to mid-May (Boise 1977). BODY WEIGHT PATTERNS Body weights of adult male and adult female Sandhill Cranes increased by an estimated 34 and 30% from arrival at the Platte River to departure from Last Mountain Lake (5 March to 28 April; Table 1). Male and female cranes collected early in the stopover period along the Platte River in Nebraska (5-14 March) weighed 3,309 and 3,135 g, respectively (Table 1). By 25 March to 3 April, average body weights of sampied males and females were 3,855 and 3,330 g. Body weights of males and females collected from early March to mid-April along the North Platte River exhibited a similar pattern of weight gain as occurred along the Platte River (Table 1). Body weights of males and females collected near the end of the stopover at the Last Mountain Lake area in Saskatchewan (24364 KRAPU, IVERSON, REINECKE, AND BOISE [Auk, Vol. 102

Book
01 Jan 1985
TL;DR: For the romantic generation of Americans in the mid-nineteenth century, the Mexican War was a grand exercise in self-identity: it legitimized the young republic's convictions of mission and destiny to a doubting world as discussed by the authors.
Abstract: "Our country has entered on a new epoch of its history," wrote a Whig Party journal in 1849, just after America's triumph in the Mexican War. Indeed, for that romantic generation of Americans in the mid-nineteenth century, the Mexican War was a grand exercise in self-identity: it legitimized the young republic's convictions of mission and destiny to a doubting world. It was easily one of the most popular wars the United States has ever fought. This rich cultural history examines the war's place in the popular imagination of the era. As Robert Johannsen notes, the Mexican War was the first American conflict to be widely reported in the press, as well as the first to be waged against an alien foe in a distant, strange, and exotic land. For mid-century Americans, Johannsen shows, the war provided a window onto the outside world, promoting an awareness--if not an understanding--of a people and a land unlike any they had known before. The war helped to dispel some of the mystery of Mexico, as it generated a huge flood of popular literature, poetry, songs, art, and stage plays. Would-be historians began chronicling the war almost as soon as the first shots were fired, and the war provoked myriad questions about the true nature and purposes of the republic. Drawing on military and travel accounts, newspaper dispatches, and a host of other sources, Johannsen vividly recreates the mood and feeling of the period--its unbounded optimism and patriotic pride. The book's unique perspective not only adds a new dimension to our understanding of the Mexican War; it offers new insights into American itself. About the Author Robert W. Johannsen is J.G. Randall Distinguished Professor of History at the University of Illinois, Urbana-Champaign and author of Stephen A. Douglas, which received the Parkman Prize of the Society of American Historians.

Journal ArticleDOI
TL;DR: The results suggest that the missing gene product in mutant 50B is required for development of the embryo proper but not for continued growth of the suspensor or endosperm tissue, and that the full developmental potential of cells in the Suspensor is expressed only when this inhibitory effect is removed.
Abstract: Developmental arrest of the embryo proper in aborted seeds from mutant 50B, a recessive embryo-lethal mutant of Arabidopsis thaliana, was shown to be followed by abnormal growth of the suspensor. Each of the 12 aborted seeds examined in sectioned material contained an abnormally large suspensor and an embryo proper arrested at a preglobular stage of development. Analysis of serial sections revealed that mutant suspensors contained 15-150 cells whereas wildtype suspensors were composed of only six to eight cells. Development of the mutant endosperm continued to a late nuclear or early cellular stage even in the absence of further development of the embryo proper. These results suggest that the missing gene product in mutant 50B is required for development of the embryo proper but not for continued growth of the suspensor or endosperm tissue. The pattern of abnormal development observed in this mutant provides further evidence that continued growth of the suspensor during normal development is inhibited by the developing embryo proper and that the full developmental potential of cells in the suspensor is expressed only when this inhibitory effect is removed through a mutation or experimental treatment that is lethal only to cells of the embryo proper. THE ZYGOTE in flowering plants develops into an early embryo composed of a terminal embryo proper and an attached suspensor. The embryo proper differentiates into the mature embryo whereas the suspensor usually degenerates during later stages of development. Many different patterns of morphogenesis have been observed in the development of the suspensor (Johansen, 1950; Maheshwari, 1950; Wardlaw, 195 5). Most members of the Cruciferae have a filamentous suspensor composed of a single file of 5-10 cells. In other families, such as the Leguminosae, the suspensor may be reduced to a single cell or enlarged into a massive structure composed of more than 100 cells (Lersten, 1983). Individual cells of the suspensor may also become polyploid, polytene, or multinucleate, or may form haustoria that invade surrounding maternal tissues. The suspensor is therefore an integral part of the plant embryo, but its size and cellular organization are highly variable. The function of the suspensor was originally thought to be limited to the passive role of attaching the embryo proper to surrounding ' Received for publication 1 1 February 1985; revision accepted 14 June 1985. This research was supported in part by NSF Grant PCM76-17222 to I. M. Sussex and NSF Grant PCM8215667 to D. W. Meinke. Initial studies were performed while M. P. F. Marsden was a Visiting Fellow at Yale University in the laboratory of Dr. Ian Sussex. 2 To whom reprint requests and correspondence should be addressed. maternal tissues (Maheshwari, 1950). The results of more recent studies on the ultrastructure of the developing suspensor (Schulz and Jensen, 1969; Schnepf and Nagl, 1970; Newcomb and Fowke, 1974; Yeung and Clutter, 1979), the transport of nutrients to the developing embryo proper (Yeung,1980), the growth in vitro of immature embryos cultured with and without a suspensor (Corsi, 1972; Cionini et al., 1976; Yeung and Sussex, 1979), the extent of endoreduplication and RNA synthesis in the developing suspensor (Sussex et al., l 973; Clutteretal., 1974;Nagl, 1974),andtheanalysis of growth regulators isolated from the massive suspensors of Phaseolus coccineus (Alpi, Tognoni and D'Amato, 1975; Lorenzi et al., 1978; Ceccarelli, Lorenzi and Alpi, 1981) and Tropaeolum majus (Przybyllok and Nagl,1977) all suggest that the suspensor plays an important role in promoting and regulating development of the early embryo proper. Much less is known about how development of the suspensor is regulated, what causes the suspensor to stop growing early in development, and how the suspensor interacts with other parts of the developing seed. Developmental interactions between the embryo proper and suspensor have been particularly difficult to study because they occur early in development when the embryo is small and deeply embedded in maternal tissue. One approach that has provided clues to the regulation of suspensor development has been

Journal ArticleDOI
TL;DR: In this paper, the optical absorption, emission and excitation spectra of Pr3+ ions in LiYF4 have been measured and an estimate of the energy transfer rate is made.

Journal ArticleDOI
TL;DR: In a crossover experiment, four dairy cows with duodenal cannulae were fed diets consisting of sorghum silage (67% of dietary dry matter) at 85% of ad libitum intake with 0 (control diet) or 44 ppm (dry matter) sarsaponin (saponin diet).

Journal ArticleDOI
TL;DR: Sera from several groups of experimental calves were tested for cytotoxin neutralizing capacity and resistance of the animals to an experimental challenge was examined, finding that undiluted bovine sera tested, other than fetal bovines serum, neutralized cytot toxin.

Journal ArticleDOI
TL;DR: High concentrations of toxic metals in Tar Creek are identified by water analysis and it is demonstrated, by removing metals via Chelex® 100 ion exchange chromatography, that the observed toxicity and teratogenicity were caused by metal ions.
Abstract: The FETAX (Frog Embryo Teratogenesis Assay — Xenopus) whole embryo bioassay has been developed to screen for environmental substances that cause birth defects. We have used this assay to test its effectiveness in working with actual water samples from the field. Tar Creek is contaminated by discharges from abandoned lead and zinc mines. In addition to high concentrations of zinc, iron and other metals, water samples are routinely low in pH and oxygen content. The pH values of three Tar Creek sample sites were below the established tolerance limits of the embryos. Therefore, one group of samples had no pH adjustment while a second group had the pH adjusted to 7.0. Two of the four sites contained agents that reduced embryonic growth and caused high rates of mortality. A third site contained teratogenic substances. We have determined that metal content is responsible, along with the low pH, for the biologic effects. We have identified high concentrations of toxic metals in Tar Creek by water analysis and were able to demonstrate, by removing metals via Chelex® 100 ion exchange chromatography, that the observed toxicity and teratogenicity were caused by metal ions. We have concluded that FETAX is an excellent test for complex mixtures. Physicochemical parameters, such as pH, oxygen and metals content, can be altered and the effect of these changes on toxicity and teratogenicity determined using FETAX. The interaction of toxic substances and low pH are important when considering embryo survival and development.

Journal ArticleDOI
TL;DR: In this article, the authors used thermoluminescence (TL) and electron spin resonance (ESR) to identify the defects responsible for the 100°C TL peak.

Journal ArticleDOI
TL;DR: The sequence of morphologic events associated with Ichthyophthirius rnultifliis invasion of gill epithelium began in the theront with differentiation of secretory mucocysts and the perforatorium and stained intensely with Mallory' stain.
Abstract: The sequence of morphologic events associated with Ichthyophthirius rnultifliis invasion of gill epithelium began in the theront with differentiation of secretory mucocysts and the perforatorium. After escaping from the cyst the theront, which stained intensely with Mallory' stain, sought a host. As it approached the host epithelium, the contents of the mucocysts were discharged, enveloping the ciliate in sticky material, which made initial contact with the host epithelium. Rapid penetration by the theront caused disruption of one or more host cells and resulted in a focal necrosis associated with the anterior margin of the ciliate. Within five minutes postexposure, the parasite completed its invasion of the epithelial layer and stained less intensely. The remnants of host cells disrupted during its entry surrounded the trophont until they were ingested by the parasite. Within 40 min postexposure, synthetic activity of the parasite appeared to increase as evidenced by an abundance of organelles, particularly ribosomes and crystalline mucocysts. At this point, the overlying host epithelium appeared normal.

Journal ArticleDOI
TL;DR: Serologic responses to B. abortus were determined by three standard tests, as well as a quantitative fluorometric immunoassay and an enzyme-linked immunosorbent assay and for individual heifers, an association could not be established between the lymphocyte blast transformation assay and the clinical response to challenge exposure.