Showing papers by "University of Nebraska–Lincoln published in 1986"

The Optimal Design of Hunting Weapons: Maintainability or Reliability

Abstract: Design engineers share archaeologists' interest in material culture, but unlike archaeologists, engineers have developed concepts for determining the suitability of technical systems to perform specific tasks. Given the difficulty archaeologists face in developing theories of material culture, I suggest that guiding principles of engineering design offer potentially useful insights. In this article I discuss two design alternatives for optimizing the availability of any technical system - reliability and maintainability. Reliable systems are made so that they can be counted on to work when needed. Maintainable ones can easily be made to function if they are broken or not appropriate to the task at hand. Because these design alternatives have markedly different optimal applications and observably different physical characteristics, archaeologists can link the design of prehistoric weapons to environmental constraints and to specific hunting strategies. Ethnographic examples indicate that primitive hunters do use both reliable and maintainable systems in optimal situations.

Age differences in eyewitness testimony

Abstract: This study examined age differences in eyewitness testimony. Children, three and six years of age, and adults interacted with an unfamiliar man for 5 minutes. Four or five days later, the witnesses answered objective and suggestive questions, recalled what happened, and tried to identify the confederate from a target-present photo line-up. The adults and 6-year-olds did not differ in their ability to answer objective questions or identify the confederate, but 6-year-olds were more suggestible than adults and recalled less about the event. Compared to the older age groups, the 3-year-olds answered fewer objective questions correctly, recalled little about what happened, and identified the confederate less frequently. In addition, they were the most suggestible. The experiment extends our knowledge of children's ability to provide accurate eyewitness reports to a very young age group and to a situation in which participants are not merely bystander witnesses but instead directly interact with the confederate.

Dimensions of Marital Quality Toward Methodological and Conceptual Refinement

Abstract: The dimensionality of five conceptually distinct components of marital quality was evaluated in a representative national sample of 1845 married people. Confirmatory factor analysis found two dimensions, one consisting of scales of marital happiness and interaction; the other, of marital disagreements, problems, and instability. Further examination of the two dimensions showed that they operate in distinctly different ways over forms of marital structure including wife's employment, marital duration, sex, and presence of children. It was concluded that scales of marital quality that combine measures from these two dimensions are likely to yield ambiguous findings and contribute little to an understanding of marital process.

Eddy fluxes of CO2, water vapor, and sensible heat over a deciduous forest

Abstract: Fluxes of CO2, latent heat and sensible heat were measured above a fully-leafed deciduous forest in eastern Tennessee with the eddy correlation technique. These are among the first reported observations over such a surface. The influences of solar radiation, vapor pressure deficit and the aerodynamic and canopy resistances on these mass and energy exchanges are examined. Following a concept introduced by McNaughton and Jarvis (1983), examination of our data suggest that the water vapor exchange of a deciduous forest is not as strongly coupled with net radiation as is that of agricultural crops. The degree of decoupling is smaller than in the case of a coniferous forest. This difference may be attributable in part to the greater aerodynamic resistance to water vapor transfer in a deciduous forest. It appears that the concept of decoupling may be extended to the CO2 exchange of a deciduous forest as well.

Sulfate and nitrate concentrations from a south Greenland ice core

Abstract: An ice core in south Greenland covering the period 1869 to 1984 was analyzed for oxygen isotopes and chloride, nitrate, and sulfate concentrations. The data show that the "excess" (nonsea-salt) sulfate concentration has tripled since approximately 1900 to 1910 and the nitrate concentration has doubled since approximately 1955. The increases may be attributable to the deposition of these chemical specis from air masses carrying North American and Eurasian anthropogenic emissions.

Skewness Persistence in Common Stock Returns

Abstract: Recent empirical studies have found expost common stock returns to be consistently posi? tively skewed. The frequency of positive skewness in this study is found to be relatively stable over varying time periods from 1961 to 1980. However, the skewness of individual stocks and portfolios of stocks does not persist across different time periods. Positivelyskewed equity portfolios in one period are not likely to be positively skewed in the next time period. Past positively-skewed returns do not predict future positively-skewed re? turns.

Fast atom bombardment and tandem mass spectrometry of phosphatidylserine and phosphatidylcholine

Abstract: Fast atom bombardment (FAB) desorption of phosphatidylserine and various phosphatidylcholines produces a limited number of very informative negative ions Especially significant is the formation of (M-H)− ions for phosphatidylserine, a compound which does not yield informative high mass ions by other ionization methods Phosphatidylcholines of not yield (M-H)− ions but instead produce three characteristic high mass ions, (M-CH 3 + _−, [M-HN(CH3) 3 + ]− and [M-HN(CH3 3 + -C2H2]− Both classes of lipids also yield anions attributed to the carboxylate components of these complex lipids FAB desorption in combination with collisional activation allows for characterization of fragmentation and determination of structural features Collisional activation of the carboxylate anion fragments from the complex lipids is especially informative Structural characterization of the fatty acid chain can be achieved as the released saturated carboxylate anions undergo a highly specific 1,4-elimination of H2, which results in the losses of the elements of CH4, C2H6, C3H8in a fashion entirely consistent with the chemistry of carboxylate anions desorbed from free fatty acids These CnH2n+2 losses begin at the alkyl terminus and progress along the entire alkyl chain Modified fatty acids undergo a similar fragmentation; however, the modification affects the series of CnH2n+2 losses in a manner which permits determining the type of modification and its location on the fatty acid chain

Southern Exposure: Deciphering the South's Influence on Homicide Rates

Abstract: Studies have consistently shown the South to have the highest homicide rates in the United States. Tzux theories to explain this have been proposed: a regionally based subculture of violence thesis and a structural interpretation emphasizing high rates of poverty in the South. These explanations are not mutually exclusive, but their proponents have engaged in a sometimes rancorous debate. Investigations designed to test the two theories have produced inconsistent findings. The present study attempts to resolve some of the questions by using OLS and ridge regression techniques to analyze state homicide rates for total populations, whites and nonwhites. Our findings show homicides for total populations and whites to be influenced by both poverty and regional differences. Among nonwhites, however, poverty is not related to the homicide rate, and the presumed effect of southern culture depends on the measurement adopted. The results lend support to arguments that the high homicide rates of white southerners and blacks reflect, in part, subcultural differences.

Children and Marital Happiness Why the Negative Correlation

Abstract: This study examines the causal processes that lead to the widely observed negative association between presence of children and marital happiness. Using a nationwide panel of 1535 married individuals, we find support for two primary causal mechanisms. First, the presence of children is associated with differences in marital structure (lower interaction, more dissatisfaction with finances and the division of labor, and more traditionalism of the division of labor) that are, in turn, associated with lower marital happiness. We also find, however, that the relationship between marital happiness and children is partially spurious. The presence of preschoolers and especially the birth of a first child serve to reduce the likelihood that unhappily married people will divorce within a three-year period. As a result, a larger proportion of unhappily married people is retained temporarily in the parent population and thus contributes to the observed negative relation between presence of children and marital happiness.

Sources of Nitrate to Ground Water

Abstract: There are a multitude of sources of nitrate to ground waters. Nitrogen undergoes a complex series of biochemical, chemical, and physical reactions in soils and waters, and thus the source of nitrate in ground waters is often difficult or impossible to ascertain with any degree of certainty. However, highly contaminated ground waters often have local sources that can be controlled. Sources of nitrate most often linked with contamination problems include septic tanks, animal and human wastes, and commercial fertilizers.

Proprioception with the proximal interphalangeal joint of the index finger: Evidence for a movement sense without a static-position sense

Abstract: Proprioceptive ability with the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the index finger in human subjects was examined using a method that could assess static-position sense independently of movement sense (Clark et al., 1985). The similarity in location and function of these joints would suggest similar proprioceptive mechanisms, but proprioceptive ability was found to be quite different for the two joints. The method of distinguishing a static-position sense from a movement sense was based on whether a subject's ability to detect a small change in joint position was impaired when the rate of rotation was progressively reduced. An awareness of static-position should not depend on the rate at which a joint is placed into position. However, if subjects use movement signals to detect changes in joint position, slowing the rate of displacement should reduce the intensity of these signals and make the displacements more difficult to detect. This method indicated a static-position sense with the MCP joint but only a movement sense with the PIP joint. It was confirmed that sensory input from regions of skin not stretched or deformed by rotation of the joint can influence proprioceptive sensibility with the fingers. Anaesthesia of the tip of the index finger or of the thumb blunted subject's perceptions of movement of the PIP joint of the index finger. However, anaesthesia of the PIP joint itself had no observable effect on the ability to sense movement of the joint.

Effects of restriction of dietary energy intake during the prepubertal period on secretion of luteinizing hormone and responsiveness of the pituitary to luteinizing hormone-releasing hormone in heifers.

Abstract: The working hypothesis that a low plane of nutrition during the prepubertal period delays puberty in heifers by retarding the prepubertal increase in secretion of luteinizing hormone (LH) was investigated. Secretion of LH and the responsiveness of the pituitary to LH-releasing hormone (LHRH) were compared in heifers fed a growing diet (which allowed spontaneous occurrence of puberty; n = 12; control) or an energy deficient diet (which delayed puberty; n = 11; delayed) during the prepubertal period. The dietary treatments were initiated when the heifers were 299 +/- 14 (mean +/- SD) d of age (d 0 of the experiment) and continued until d 175 of the experiment (474 +/- 14 d of age). Weight gains were .79 +/- .05 (mean +/- SE) and .21 +/- .03 kg X head-1 X d-1 for control and delayed heifers, respectively. Puberty occurred on d 120 +/- 14 of the experiment (428 +/- 13 d of age) in control heifers, whereas none of the delayed heifers attained puberty during the feeding period. Serum concentration of LH and the frequency of LH pulses increased rapidly during the 175-d feeding period in control heifers. In delayed heifers, serum LH concentration increased less rapidly and no increase in pulse frequency was detected during the experimental period. Amplitude of LH pulses tended to be higher in control than delayed heifers. Responsiveness of LH secretion to LHRH was lower in delayed than control heifers. It is speculated that failure of secretion of LH to increase is the causative factor for delayed puberty when dietary energy is limited during the prepubertal period in heifers.

A Model of Sales Supervisor Leadership Behavior and Retail Salespeople's Job-Related Outcomes:

Abstract: Retail salespeople play an important role in a retailer’s marketing mix, yet little empirical research has examined how retail managers might assist sales personnel in the performance of their jobs. This paper reports the results of a study that explored a causal model of sales supervisor “leadership behavior” and seven job-related outcomes of retail salespeople. Implications for retailers and researchers are provided.

Document analysis with an expert system

Abstract: With the decreasing cost of secondary storage it is becoming attractive to store optically scanned technical documents such as reports and articles in digital form as an array of pixels. The array may be compressed with techniques based on run-length coding. In many applications, it is desirable to access only a portion of the document, such as the title, author, abstract, or bibliography. With a knowledge base comprising layout and composition rules for specific classes of documents, these documents may be automatically subdivided into nested rectangles corresponding to meaningful blocks. The resulting structure is represented as a tree. An algorithm is proposed for assigning labels to the blocks according to their location, extent, and relative position with respect to other (possibly already labeled) blocks.

Characterization of somatic embryogenesis and plant regeneration in cotton (Gossypium hirsutum L.).

Abstract: Seventeen cultivars of cotton (Gossypium hirsutum L.) were evaluated for callus initiation and maintenance using 3 initiation media and 3 maintenance media. After a series of transfers of a 3% glucose media, calli were placed on a 3% sucrose medium. After several weeks calli were observed for the presence of embryo-like structures. Cultivars Coker 201 and Coker 315 were identified as embryogenic. Embryogenic callus has since been routinely obtained within 6 weeks by initiating callus on glucose media for 3-4 weeks followed by transfer to sucrose media. Histological examination has shown that embryos are derived from isodiametric, densely cytoplasmic cells and follow predictable patterns of development. Upon maturity, transfer to auxin-free media with reduced sucrose levels results in embryo germination. Regenerated plants can be transferred to greenhouse within 90 days of callus initiation.

Response to monensin in cattle during subacute acidosis.

Abstract: A steer metabolism study was conducted to measure changes in ruminal and blood components in response to monensin level following an abrupt switch from forage to a concentrate diet. Six ruminai-cannulated crossbred steers (373 kg) were fed either O, 150 or 300 mg monensin per head daily in a replicated 3 X 3 Latin-square design. In all treatments, ruminal pH declined to a low of 5.4 to 5.6 12 h post-feeding, suggesting steers experienced subacute acidosis. Also in the first 12 h post-feeding, all treatments exhibited nearly a twofold increase in total ruminal volatile fatty acid (VFA) concentrations, while peak ruminal lactate concentrations ranged from .86 to 1.50 raM. During the entire 48-h period, there were no significant treatment differences in blood pH, HCO- 3 or ruminal lactate, although there was a trend of higher ruminal and blood lactate associated with increased level of monensin supplementation. Feeding higher levels of monensin resulted in higher pH and propionate with lower acetate and butyrate concentrations. Increasing the level of monen- sin fed resulted in reduced (P<.OI) total ruminal VFA concentrations. Ruminal pH was more highly correlated to total ruminal VFA concentrations (r=-.69, P<.O1) than lactate concentrations (r=--.14, P<.IO). Results from this study indicate the significance of total ruminal organic acid concentration rather than ruminal lactate concentration during subacute acidosis. Monensin maintained a higher ruminal pH by reducing concentrations of VFA. (Key Words: Monensin, Acidosis, Volatile Fatty Acids, Steers.)

Hydrogeology of an Atoll Island: A Conceptual Model from Detailed Study of a Micronesian Example

Abstract: Findings from a detailed hydrogeologic study of a Micronesian atoll island are combined with published descriptions of the hydrogeology of other atoll islands. The purpose is to propose a conceptual model which describes how the occurrence and flow of ground water in atoll islands are related to the underlying geologic framework. The study island is Deke, a small, uninhabited island on Pingelap Atoll in the Eastern Caroline Islands. Integrated studies on Deke of surface geology and physiography, water levels and their variation, surface geophysics (seismic refraction and resistivity), and subsurface core samples indicate a hydrogeologic system that is more complex than would ordinarily be expected for a small and, at first glance, uncomplicated island. Of utmost importance to the occurrence and flow of ground water is the fact that the island straddles the lagoonward edge of the very firmly indurated reef-flat plate. This plate is a hard, impermeable substrate beneath the northern portion (ocean side) of the island, occurs at sea level, and is underlain by unconsolidated or loosely cemented sediments. Study results indicate that this reef-flat plate acts as a confining bed along the ocean side of the lens; elsewhere the lens is unconfined, receives recharge directly, and forms a thicker fresh-water nucleus. The conceptual model of atoll-island hydrogeology involves a dual aquifer system: (1) an aquifer of mostly unconsolidated Holocene sediments resting on (2) a once emergent and now very permeable Pleistocene limestone platform. The Holocene aquifer, which is where the island lens occurs, is heterogeneous with respect to its hydraulic properties and is confined in part of the island and unconfined elsewhere, with the location of the two regions depending on where the island sits relative to the pinchout of the reef-flat plate. In the unconfined region, there is a hydrologically-important central depression, where low lying sediments are enclosed by ocean-derived washover fans and a lagoon-bordering dune. This area is a likely ground-water sink due to direct evapotranspiration during the dry season. Accordingly, the model includes two flow patterns: a wet-season pattern radiating outward from the unconfined lagoon-side of the island, and a dry-season pattern that includes a superimposed area of centripetal flow at the central depression.

Natural and experimental infection with an attaching and effacing strain of Escherichia coli in calves.

Abstract: Gnotobiotic calves were inoculated with an O5:K4:H-, urease-positive strain of Escherichia coli isolated from a 2-day-old calf with diarrhea. The calves developed elevated temperatures and passed loose mucoid feces, with or without blood. The E. coli strain was negative for heat-stable and heat-labile enterotoxins but produced high levels of Shiga-like toxin. Bacteria attached diffusely to the epithelium of the large intestine and multifocally to the epithelium of the ileum. The duodenum and jejunum were not affected. At the sites of bacterial attachment, microvilli were effaced, enterocytes were degenerate, and necrosis and exfoliation had occurred. These results confirm a previous report from England that calves may naturally contract infections similar to those caused by enteropathogenic E. coli strains pathogenic to humans or rabbits. This suggests that the calf bacterial strains, like some enteropathogenic E. coli strains, produce high levels of Shiga-like toxin and cause attachment and effacement lesions in the colonic epithelium of the infected host. Images

Beacons in computer program comprehension

Abstract: In programming, beacons are lines of code which serve as typical indicators of a particular structure or operation. This research sought evidence for the existence and use of beacons in comprehension of a sort program. In the first experiment, subjects memorized and later recalled the whole sort program. Experienced programmers, but not novices or intermediates, recalled the beacon lines much better than non-beacon lines. In the second experiment, experienced programmers studied the same program and then were asked to recall several isolated parts of it. They did not know in advance that they would be asked to recall. Subjects recalled the beacon much better than non-beacon parts. They also were more certain that they recalled the beacon correctly. The results of both experiments support the idea that beacons exist as a focal point for study and understanding of programs by experienced programmers.

Teacher Perceptions of School-Based Interventions

Abstract: This article reports the results of a study investigating teachers' perceptions of intervention alternatives used to control classroom behavior problems. Regular and special educators from a two-state area completed a 65-item questionnaire assessing teachers' perceptions of the relative effectiveness, ease of use, and frequency of use of a variety of intervention strategies for the treatment of classroom behavior problems. Results indicated that teachers' responses factored into clearly defined categories. Further, teachers differentially rated these categories in terms of their relative effectiveness, ease of use, and frequency of use. Strategies rated as most effective, easiest to use, and most frequently used by both regular and special educators included interventions that either redirected students toward appropriate behavior or that involved manipulation of rewards. Results are discussed in terms of their implications for school-based consultants who interact with teachers concerning the control, of...

The effects of handle shape and size on exerted forces.

Abstract: This research empirically evaluated the effects of handle shape and size on the hand's ability to resist or exert force in six directions. Thirty-six handles of four sizes and nine shapes were tested for maximum force exertion by male and female subjects. The results show that subjects were able to generate higher forces with different sizes and shapes of handles, depending upon the direction of force exertion. This suggests that handles that are associated with high forces on particular directional tests are probably suited for tasks that incorporate that particular type of force or movement; they may not be appropriate for other tasks that do not incorporate such movement.

Exercise training effects on serum lipids of prepubescent boys and adult men.

Abstract: The effects of 10 wk of exercise training at low (40% VO2max) or high (75% VO2max) intensity on serum lipids and lipoproteins were compared in prepubescent boys and adult men. The final sample size consisted of: 8 boys (mean +/- SE age = 8.5 +/- 1.96 yr) and 8 men (36.6 +/- 3.18 yr) in low; 12 boys (8.0 +/- 1.40 yr) and 12 men (36.6 +/- 4.09 yr) in high; and 10 boys (9.0 +/- 2.08 yr) and 10 men (36.7 +/- 4.82 yr) in control. Training involved walking/jogging/running 3 d X wk-1 at a distance which progressed from 2.4 km X d-1 in the first week to 4.8 km X d-1 from the fifth week. Fasting blood samples, collected on 2 d during both pre- and post-training, were assayed for triglycerides, total cholesterol (CHOL), and high density lipoprotein cholesterol (HDL-C). Maximum aerobic power (VO2max) was determined from a treadmill test. Additionally, dietary intake was assessed from a 3-d dietary record and body composition from the sum of 6 skinfolds. The only statistically significant (P less than 0.05) changes occurred in HDL-C and CHOL for the high groups. HDL-C decreased following training. CHOL was lower for high than the other groups for the first day post-training only. There were no differences in the changes in HDL-C/CHOL ratio among the groups. VO2max only increased in the high groups. Dietary intake and body weight did not change. Further statistical adjustment in lipids for changes in sum of 6 skinfolds did not alter the results.(ABSTRACT TRUNCATED AT 250 WORDS)