Showing papers by "University of Nebraska–Lincoln published in 1988"
TL;DR: Two stochastic processes that model the major modes of dispersal that are observed in nature are introduced, and explicit expressions for the mean squared displacement and other experimentally observable quantities are derived.
Abstract: In order to provide a general framework within which the dispersal of cells or organisms can be studied, we introduce two stochastic processes that model the major modes of dispersal that are observed in nature. In the first type of movement, which we call the position jump or kangaroo process, the process comprises a sequence of alternating pauses and jumps. The duration of a pause is governed by a waiting time distribution, and the direction and distance traveled during a jump is fixed by the kernel of an integral operator that governs the spatial redistribution. Under certain assumptions concerning the existence of limits as the mean step size goes to zero and the frequency of stepping goes to infinity the process is governed by a diffusion equation, but other partial differential equations may result under different assumptions. The second major type of movement leads to what we call a velocity jump process. In this case the motion consists of a sequence of "runs" separated by reorientations, during which a new velocity is chosen. We show that under certain assumptions this process leads to a damped wave equation called the telegrapher's equation. We derive explicit expressions for the mean squared displacement and other experimentally observable quantities. Several generalizations, including the incorporation of a resting time between movements, are also studied. The available data on the motion of cells and other organisms is reviewed, and it is shown how the analysis of such data within the framework provided here can be carried out.
905 citations
TL;DR: The c-mos proto-oncogene is expressed as a maternal mRNA in oocytes and early embryos of Xenopus laevis, but its translation product pp39mos is detectable only during progesterone-induced oocyte maturation, indicating that it functions during reinitiation of meiotic division.
Abstract: The c-mos proto-oncogene is expressed as a maternal mRNA in oocytes and early embryos of Xenopus laevis, but its translation product pp39mos is detectable only during progesterone-induced oocyte maturation. Microinjection of mos-specific antisense oligonucleotides into oocytes not only prevents expression ofpp39mos, but also blocks germinal vesicle breakdown, indicating that it functions during reinitiation of meiotic division.
573 citations
TL;DR: The List of Values (LOV), a methodology that may allow comparison and contrast of values, is described, and data analysis strategies are discussed.
Abstract: Research on social values has been shown to be beneficial in market segmentation. This article describes the List of Values (LOV), a methodology that may allow comparison and contrast of values. Details of the methodology and recent research using it are described, and data analysis strategies are discussed.
324 citations
TL;DR: Theoretical expressions for the internal and external electromagnetic fields for an arbitrary electromagnetic beam incident upon a homogeneous spherical particle are derived, and numerical calculations based upon this theoretical development are presented in this paper.
Abstract: Theoretical expressions for the internal and external electromagnetic fields for an arbitrary electromagnetic beam incident upon a homogeneous spherical particle are derived, and numerical calculations based upon this theoretical development are presented. In particular, spatial distributions of the internal and near‐surface electric field magnitude (source function) for a focused fundamental (TEM00 mode) Gaussian beam of 1.06 μm wavelength and 4 μm beam waist diameter incident upon a 5‐μm‐diam water droplet in air are presented as a function of the location of the beam focal point relative to the sphere center. The calculations indicate that the internal and near‐surface electric field magnitude distribution can be strongly dependent upon relative focal point positioning and may differ significantly from the corresponding electric field magnitude distribution expected from plane‐wave irradiation.
300 citations
TL;DR: In this article, a two-stage procedure for the design of a cellular manufacturing system is proposed, where the first stage forms the part families and the second stage form the machine cells.
Abstract: A two-stage procedure for the design of a cellular manufacturing system is proposed. The first stage forms the part families. The use of clustering techniques with a new proximity measure is advocated for this stage. The proximity measure uses the manufacturing operations and the operations' sequences. The second stage forms the machine cells. An integer programming model is proposed for this stage. The solution of this model will specify the type and the number of machines in each cell and the assignment of the part families to the cells. The relevance of this approach in the design of flexible manufacturing systems is discussed.
273 citations
TL;DR: In this article, the authors explored the equivalence of successful managers and effective managers and found that successful managers may not be the effective managers, the ones with satisfied, committed subordinates turning out quantity and quality performance in their units.
Abstract: W hat do successful managers those who have been promoted relatively quickly have in common with effective managers those who have satisfied, committed subordinates and high performing units? Surprisingly, the answer seems to be that they have little in common. Successful managers in what we define as "real organizations" large and small mainstream organizations, mostly in the mushrooming service industry in middle America are not engaged in the same day-to-day activities as effective managers in these organizations. This is probably the most important, and certainly the most intriguing, finding of a comprehensive four-year observational study of managerial work that is reported in a recent book by myself and two colleagues, titled Real Managers.1 The startling finding that there is a difference between successful and effective managers may merely confirm for many cynics and "passed over" managers something they have suspected for years. They believe that although managers who are successful (that is, rapidly promoted) may be astute politicians, they are not necessarily effective. Indeed, the so-called successful managers may be the ones who do not in fact take care of people and get high performance from their units. Could this finding explain some of the performance problems facing American organizations today? Could it be that the successful managers, the politically savvy ones who are being rapidly promoted into responsible positions, may not be the effective managers, the ones with satisfied, committed subordinates turning out quantity and quality performance in their units? This article explores the heretofore assumed equivalence of "successful managers" and "effective managers." Instead of looking for sophisticated technical or governmental approaches to the performance problems facing today's organizations, the solution may be as simple as promoting effective managers and learning how they carry out their jobs. Maybe it is time to turn to the real managers themselves for some answers. And who are these managers? They are found at all levels and in all types of organizations with titles such as department head, general manager, store manager, marketing manager, office manager, agency chief, or district manager. In other words, maybe the answers to the performance problems facing organizations today can be found in their own backyards, in the managers themselves in their day-today activities. The Current View of Managerial Work
261 citations
TL;DR: Biochemical studies with strains of Escherichia coli that are amplified for the products of the three fumarase genes have shown that there are two distinct classes of fumarases, and it is suggested that the Class I enzymes may belong to a wider family of iron-dependent carboxylic acid hydro-lyases that includes maleate dehydratase and aconitase.
236 citations
TL;DR: In this paper, normal corn starch was extrusion-cooked in a C. W. Brabender Laboratory model single-screw extruder at various extruder barrel temperatures, screw speeds, feed rates, and moisture contents.
Abstract: Normal corn starch was extrusion-cooked in a C. W. Brabender Laboratory model single-screw extruder at various extruder barrel temperatures, screw speeds, feed rates, and moisture contents. The expansion ratios and shear strengths of the products were highly dependent on extrusion-cooking conditions. The maximum expansion ratio of 16.1 was obtained when 14% moisture content (d.b.) starch was fed at a rate of 60g min-1 with a screw speed of 150 rpm, a barrel temperature of 140°C and a die-nozzle L/D ratio of 3.1. The shear strengths of the extruded starch products were inversely proportional to the expansion ratios.
213 citations
TL;DR: This article examined four models of the way in which premarital cohabitation may affect marital quality using interview data from a national probability sample of married persons, and found that co-habitation is negatively related to marital interaction and positively related with marital disagreement, proneness to divorce, and the probability of divorce in nonminority populations.
Abstract: Four models of the way in which premarital cohabitation may affect marital quality are examined using interview data from a national probability sample of married persons. The idea that cohabitation improves mate selection and marital training is rejected. Cohabitation is negatively related to marital interaction and positively related to marital disagreement, proneness to divorce, and the probability of divorce in nonminority populations. No evidence is found that the accelerated marriage model explains these findings. Some support is found for the explanation that some of those who cohabit are poor marriage risks before they marry. No support is found for the idea that cohabitation itself causes a decline in marital quality, but this argument cannot be rejected with confidence, given the data at hand.
205 citations
TL;DR: This paper will distil some of the recent empirical developments in the literature on social support, particularly in those areas that have received less attention in prior reviews.
Abstract: Early research on life-stress grappled with the question of whether significant life-events bring about changes in health status. The emphasis has now shifted to the identification of factors that explain why some people seem to be so severely affected by life's adversities and others are not. From a class of what might be called 'vulnerability variables' (Kessler, 1979), support from one's social network has emerged as a significant factor that can account for at least some of the vulnerability differences between groups of stressed individuals. Since Cassel's (1974) review of the evidence linking social upheavals to adverse health consequences for both humans and animals, hundreds of empirical studies have been completed that assess the direct and indirect effects of social support on mental and physical health. This literature is so voluminous as to require several books devoted to reviews of various aspects of it (e.g. Cohen & Syme, 1985; Gottlieb, 1981; and Gottlieb, 1983). In this paper we will distil these as well as highlight some of the recent empirical developments, particularly in those areas that have received less attention in prior reviews. Social support has been defined as the presence of others, or the resources provided by them, prior to, during, and following a stressful event. While there is no general agreement on a single definition, the variety has spawned a number of typologies attempting to organize the literature (e.g. Cohen & Syme, 1985; Cohen & Wills, 1985; Gottlieb, 1983; House & Kahn, 1985). Most of these typologies initially distinguish between functional and structural operationalizations of social support.
TL;DR: Dideoxy protocols have been determined that provide sequences for 600 bases starting with base 1 with less than 1% error in a single load.
Abstract: A method for sequencing DNA by using a difluoresceinated primer and laser excitation is described. Dideoxy protocols have been determined that provide sequences for 600 bases starting with base 1 with less than 1% error in a single load. Electrophoresis is at 20 W and the bands are detected 24 cm from the bottom of the loading well with a scanning fluorescence detector. Bands are imaged on a TV screen in two dimensions. The sequences can be read from the TV screen manually or semiautomatically by using a simple software program. The system allows more bases to be read with a lower error rate than any other reported automated sequencing method.
TL;DR: A test for the mutant allele in a cloned fragment of the HEXA gene revealed that this case and two other cases of the Ashkenazi, infantile form of Tay-Sachs disease are heterozygous for two different mutations, warrants further examination of the selective advantage hypothesis.
Abstract: Tay-Sachs disease is an autosomal recessive genetic disorder resulting from mutation of the HEXA gene encoding the α-subunit of the lysosomal enzyme, β-N-acerylhexosaminidase A (ref. 1). A relatively high frequency of carriers (1/27) of a lethal, infantile form of the disease is found in the Ashkenazi Jewish population, but it is not yet evident whether this has resulted from a founder effect and random genetic drift or from a selective advantage of heterozygotes2. We have identified a single-base mutation in a cloned fragment of the HEXA gene from an Ashkenazi Jewish patient. This change, the substitution of a C for G in the first nucleotide of intron 12 is expected to result in defective splicing of the messenger RNA3. A test for the mutant allele based on amplification of DNA by the 'polymerase chain rection'4 and cleavage of a DdeI restriction site generated by the mutation revealed that this case and two other cases of the Ashkenazi, infantile form of Tay-Sachs disease are heterozygous for two different mutations. The occurrence of multiple mutant alleles warrants further examination of the selective advantage hypothesis.
TL;DR: Results with the purified enzyme from light- and dark-adapted maize leaves indicate that the light-induced changes in activity and malate sensitivity of C4 PEPCase are related, at least in part, to the degree of covalent seryl phosphorylation of the protein in vivo.
TL;DR: The ability of Listeria monocytogenes to survive and grow on head lettuce obtained from a retail outlet over a period of 10 months was determined and it was found that the organism was naturally present on some of the lettuce heads purchased from retail outlets.
TL;DR: In this paper, the influence of the environment and nitrogen fertility upon light interception efficiency (ei) and light use efficiency (ec) of winter wheat (Triticum aestivum L.) were examined using remotely sensed canopy reflectance data to estimate ei.
TL;DR: Ochratoxin formation by Aspergillus ochraceus was consistently enhanced by irradiation of spores or mycelium, andAflatoxin production was increased in irradiated wheat grain, but decreased in barley and maize when the grain was irradiated prior to inoculation.
TL;DR: It is argued that large T{sub c} values have a purely vibronic origin.
Abstract: A mechanism to explain high-T{sub c} superconductivity, based on the double-well motion of the oxygen ions in such systems, is extended to predict T values of for (La, Ba){sub 2}CuO{sub 4} and Ba{sub 2}Cu{sub 3}O{sub 7}. This gives lower bounds on T{sub c} of 53K for the former and 44K for the latter. Since the second number, in particular, could be markedly enhanced by full allowance for the large amplitudes of the oxygen motions, it is argued that large T{sub c} values have a purely vibronic origin.
TL;DR: In this paper, the relative positions of the plumes combined with an historical review of total plant output of RDX and TNT indicate that RDX is much more persistent than TNT.
TL;DR: Shelterbelts provide benefits to wildlife in several ways, including protection from wind and adverse weather, escape or refuge cover, food and foraging sites, reproductive habitat and travel corridors as discussed by the authors.
TL;DR: Anaerobic capacity and AWC were significantly (p 0·05) differences between the test-retest means for CP or AWC, and test- retest correlations for CP (r=0·94) a...
Abstract: The purpose of this study was to determine the relationship between anaerobic work capacity (AWC) and anaerobic capacity (AC) from the Critical Power (CP) and ‘Wingate’ tests, respectively. A secondary purpose was to determine the reliability of AWC and CP. Twenty-five females (mean±s.d. = 21·88±2·49 years) volunteered to perform a ‘Wingate’ test and two Critical Power tests all on separate days. Anaerobic capacity was defined as the total work performed during the 30-second ‘Wingate’ test. The relationship between work limit (total work to exhaustion) and time limit (total time to exhaustion), calculated for each of the three work bouts of the CP test, was linear (r 2 =0·98−1·00) for all of the subjects. The slope and Y intercept of this relationship represented CP and AWC, respectively. Anaerobic capacity and AWC were significantly (p 0·05) differences between the test-retest means for CP or AWC. Test-retest correlations for CP (r=0·94) a...
TL;DR: An agar medium with improved selection for Treponema hyodysenteriae was developed and colonic specimens from naturally occurring cases of porcine intestinal disease were plated on TSA-S400 and BJ.
Abstract: An agar medium with improved selection for Treponema hyodysenteriae was developed. Cultures of T. hyodysenteriae and T. innocens, feces from 11 clinically normal pigs, and colonic contents from 6 pigs with gross lesions consistent with swine dysentery were diluted in phosphate-buffered saline and plated on Trypticase soy agar (BBL Microbiology Systems, Cockeysville, Md.) with 5% citrated bovine blood (TSA), TSA with 400 micrograms of spectinomycin per ml (TSA-S400), TSA-S400 with 25 micrograms each of colistin and vancomycin per ml, and TSA with 5% pig feces extract and five antimicrobial agents (spiramycin, rifampin, vancomycin, colistin, and spectinomycin) (BJ). Viable numbers of T. hydodysenteriae grown on BJ were virtually identical to those for TSA, TSA-S400, and TSA-S400 with colistin and vancomycin. Pure cultures of four isolates of T. hyodysenteriae and three isolates of T. innocens were sustained through six subcultures on BJ. Fecal floras were completely inhibited on BJ for 14 of 17 fecal samples from both groups of pigs. A total of 461 colonic specimens from naturally occurring cases of porcine intestinal disease were plated on TSA-S400 and BJ. T. hyodysenteriae was isolated on both TSA-S400 and BJ for 69 specimens and on BJ alone for an additional 19 specimens.
TL;DR: The findings suggest that as children enter adolescence, general competence becomes more closely bound up with the quality of sibling relations and the degree of parental control, and less closely Bound up with support from parents.
Abstract: Associations were examined between 12 measures of family process and 6 measures of personal and social competence for 102 adolescents aged 15-16 and 99 children aged 8-9. Canonical correlations analysis revealed that general competence among primary school children was associated with high levels of support from parents, a high allocation of household responsibility, a high level of parental control, and a low level of parental punishment. Among adolescents, general competence was associated with a high level of support from parents, a low level of parental control, a high allocation of household responsibility, parental use of induction, a low level of parental punishment, high-quality sibling relationships, and high family cohesion. The findings suggest that as children enter adolescence, general competence becomes more closely bound up with the quality of sibling relations and the degree of parental control, and less closely bound up with support from parents.
TL;DR: The variability of Pennsylvania winter climate is the result of mechanisms working on two distinctly different time scales: interdecadal and interannual as mentioned in this paper, which is associated with hemispheric changes in large-scale atmospheric circulation regimes.
Abstract: The variability of Pennsylvania winter climate is shown to be the result of mechanisms working on two distinctly different time scales: interdecadal and interannual. Interdecadal variability is associated with hemispheric changes in large-scale atmospheric circulation regimes. During periods of zonal flow, Pennsylvania temperatures are above normal, while meridional flow is associated with below-normal temperatures. Precipitation is near normal during zonal regimes, but can be either very dry (as it was in the 1960s) or abnormally wet (like the 1970s) with meridional flow, depending on the exact placement of the deepened trough over the eastern United States. Imbedded in the interdecadal fluctuations is interannual variability which is related to two important Northern Hemisphere teleconnection patterns: the Pacific/North American (PNA) and North Atlantic Oscillation (NAO) patterns. Interannual changes in the atmospheric circulation, as expressed by indices of the two teleconnections, explain 50 ...
TL;DR: Systematic analysis of the results of the most recent tests along with the published results of other blind tests provide strong support for the efficacy of polish-based microwear analysis.
TL;DR: Translation in vitro indicated that elevated mRNA levels were at least partially responsible for the specific increase in vegetative storage protein mRNA in leaves of depodded plants.
Abstract: Depodded soybean (Glycine max [L] Merr. cv Williams) plants accumulate high levels of a glycoprotein in their leaves that has many features of a storage protein. The protein is found in all vegetative tissues which have been examined but not in the seeds. Translation in vitro indicated that elevated mRNA levels were at least partially responsible for the specific increase in vegetative storage protein. cDNA clones were isolated and sequenced, and an amino acid sequence was predicted. Although the amino acid composition is similar to that of seed storage proteins, no sequence similarity could be detected. Northern blot hybridization confirmed a large increase in vegetative storage protein mRNA in leaves of depodded plants. The vegetative storage proteins are represented by about four gene copies in the haploid genome.
TL;DR: A methodology based on fuzzy set theory for the utilization of imprecise data in geostatistics is presented and is applied to the permeability prediction of a soil liner for hazardous waste containment.
Abstract: A methodology based on fuzzy set theory for the utilization of imprecise data in geostatistics is presented. A common problem preventing a broader use of geostatistics has been the insufficient amount of accurate measurement data. In certain cases, additional but uncertain (soft) information is available and can be encoded as subjective probabilities, and then the soft kriging method can be applied (Journel, 1986). In other cases, a fuzzy encoding of soft information may be more realistic and simplify the numerical calculations. Imprecise (fuzzy) spatial information on the possible variogram is integrated into a single variogram which is used in a fuzzy kriging procedure. The overall uncertainty of prediction is represented by the estimation variance and the calculated membership function for each kriged point. The methodology is applied to the permeability prediction of a soil liner for hazardous waste containment. The available number of hard measurement data (20) was not enough for a classical geostatistical analysis. An additional 20 soft data made it possible to prepare kriged contour maps using the fuzzy geostatistical procedure.
TL;DR: The results demonstrate that chloroplast genetic modification of the CO2/O2 specificity factor of a plant-type carboxylase/oxygenase is feasible and support previous studies that implicated this region of the large subunit as an important structural component of the enzyme's function.
Abstract: The Chlamydomonas reinhardtii chloroplast mutant 68-4PP is phenotypically indistinguishable from wild type at 25 degrees C but fails to grow photosynthetically at 35 degrees C. It had about 30% of the wild-type level of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) holoenzyme and carboxylase activity when grown at 25 degrees C, but less than 15% when grown at 35 degrees C. Pulse-labeling with 35S showed that the decrease in enzyme level at the restrictive temperature was not a result of reduced synthesis of enzyme subunits. The CO2/O2 specificity factor (VCKO/VOKC, where VC and VO are Vmax values for carboxylation and oxygenation and KC and KO are Km values for CO2 and O2) of the mutant enzyme was found to be significantly less than that of the wild-type enzyme (54 +/- 2 and 62 +/- 1, respectively), and this alteration was accompanied by increases in KO and KC and a decrease in VC/VO. DNA sequencing revealed a single missense mutation in the 68-4PP chloroplast large-subunit gene. This mutation causes leucine to be replaced by phenylalanine at position 290 in the large-subunit polypeptide sequence. These results (i) support previous studies that implicated this region of the large subunit as an important structural component of the enzyme's function and (ii) demonstrate that chloroplast genetic modification of the CO2/O2 specificity factor of a plant-type carboxylase/oxygenase is feasible.
TL;DR: This paper reviews the seven specific plant enzymes which have been shown or suggested, to date, to undergo reversible covalent modification by regulatory phosphorylation, including mitochondrial pyruvate dehydrogenase, and ribulose bisphosphate carboxylase/oxygenase.
Abstract: This paper reviews the seven specific plant enzymes which have been shown or suggested, to date, to undergo reversible covalent modification by regulatory phosphorylation, including mitochondrial pyruvate dehydrogenase (EC 1.2.4.1), chloroplastic pyruvate, orthophosphate dikinase (EC 2.7.9.1) and ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39), cytoplasmic phosphoenolpyruvate carboxylase (EC 4.1.1.31) and 6-phosphofructo-2-kinase (EC 2.7.1.105), microsomal hydroxymethylglutaryl - CoA reductase (EC 1.1.1.34), and quinate: NAD+ oxidoreductase (EC 1.1.1.24).