Showing papers by "Iowa State University published in 1983"

Concept Redundancy in Organizational Research: The Case of Work Commitment

Abstract: A facet design describing the theoretical and empirical interrelationships among five forms of work commitment (Protestant work ethic, career salience, job involvement/work as a central life interest, organizational commitment, and union commitment) is presented. The analysis reveals that these concepts are partially redundant and insufficiently distinct to warrent continued separation. Suggestions for advancing the study of work commitment are rendered.

Supervisory Behavior, Role Stress, and the Job Satisfaction of Industrial Salespeople:

Abstract: Structural equation analysis was used to replicate and extend previous salesforce role stress research by testing hypotheses about the relationships among sales supervisory behavior, salesforce rol...

A model relating ultrasonic scattering measurements through liquid–solid interfaces to unbounded medium scattering amplitudes

Abstract: The relationship between scattering data obtained from ultrasonic experiments, in which the waves are excited and detected in a finite measurement geometry, and unbounded medium, farfield scattering amplitudes is considered. For a scatterer in a single fluid medium, a Green’s function approach is used to develop an approximate, but absolute, relationship between these experimental and theoretical cases. Electromechanical reciprocity relationships are then employed to generalize to a two medium case in which the scatterer is located in an elastic solid which, along with the ultrasonic transducer, is immersed in a fluid medium. The case explicitly considered is one in which the incident waves are quasiplanar over the volume of the flaw and the scattering amplitudes are slowly varying over the range of angles subtended by the receiving transducer. Analytic approximations are developed for the absolute relationship of the received transducer signal to the unbounded medium scattering amplitudes, and formal exp...

A simple method for determination of ammonium in semimicro‐Kjeldahl analysis of soils and plant materials using a block digester

Abstract: A simple method for determination of ammonium in semimicro‐Kjeldahl analysis of soils and plant materials using a Tecator or Technicon 40‐tube block digester is described. It involves use of an ine...

Power system transient stability using individual machine energy functions

Abstract: Recent efforts to apply direct methods of transient stability analysis to multimachine power systems have used the so-called "energy functions." These functions describe the system transient energy causing the synchronous generators to depart from the initial equilibrium state, and the power network's ability to absorb this energy so that the synchronous machines may reach a new post-disturbance equilibrium state. Recent results have shown that not all the transient energy contributes to system separation. Indeed it has become increasingly evident that system separation depends on the energy of certain individual machines or groups of machines, which comprise the critical group, and which tend to separate from the rest of the machines (which make up the noncritical group). Thus there is a need for generating energy functions for individual machines (or for groups of machines). Using a center of inertia frame of reference, the energy function V_{i} for machine i is derived. A procedure for first swing transient stability assessment is developed using the energy function of individual machines and groups of machines. The method is tested extensively on two realistic power networks (the 20-generator IEEE System and the 17-generator reduced Iowa System). An analytical justification for using the critical energy of individual machines in stability assessment is provided using an invariance principle for ordinary differential equations. Power system transient stability is analyzed using the energy function of the critical group of machines. This energy function is dependent on all state variables of the power system, and satisfies the hypotheses of the invariance theorem of La Salle, enabling us to deduce the asymptotic stability of the post-disturbance equilibrium of the entire power system. It also enables us to obtain an estimate of the domain of attraction of this equilibrium of the entire power system. The methodology advanced herein, which combines computer-aided techniques with analytical tools, yields less conservative results than were obtained in previous works that used total system energy. It is to be noted that the present results are preliminary in the sense that the mechanism of separation of the critical group of machines from the rest of the system needs further investigation.

Observability, Eigenvalues, and Kalman Filtering

Abstract: In higher order Kalman filtering applications the analyst often has very little insight into the nature of the observability of the system. For example, there are situations where the filter may be estimating certain linear combinations of state variables quite well, but this is not apparent from a glance at the error covariance matrix. It is shown here that the eigenvalues and eigenvectors of the error covariance matrix, when properly normalized, can provide useful information about the observability of the system.

Nectar production patterns in Ipomopsis aggregata (Polemoniaceae).

Abstract: This study describes nectar production patterns for Ipomopsis aggregata and discusses their potential adaptive and ecological significance. It also examines the influence of environmental and other factors on nectar production rate (NPR) and nectar sugar concentration. For I. aggregata there were no NPR differences with flower age. An hypothesis for the presence or absence of such differences is discussed. Ipomopsis aggregata has a relatively constant rate of nectar production during the day and production continues overnight but at a reduced rate. Newly opened flowers already have a sizeable accumulation of nectar. 24-hr nectar sugar production on overcast days was 62% of sunny day production. NPR values at the beginning ofthe flowering season were almost twice as great as those near the end but the sugar concentration did not change. Whether nectar was removed periodically (to simulate pollinator visits) or simply allowed to accumulate over 24 hr had no effect on total production. Nectar sugar concentration has a characteristic diumal pattern: highest in the afternoon and lowest in the early morning, probably in response to diurnal changes in relative humidity. Sugar concentration was also lower on overcast days. These changes are not due to evaporative losses from the open end of the flower. However, evaporation did occur in flowers which had been punctured at the base of the corolla by nectar robbing bees. In general the results of this study suggest caution in characterizing the NPR or sugar concentration of a species by making measurements at one point in time under one set of environmental conditions. A PLANT S NECTAR PROPERTIES are an integal part of its strategy for pollination success. There are a number of nectar properties of interest including the sugar concentration of the nectar (Baker, 1975; Pyke and Waser, 198 1), the composition of sugars in the nectar (Baker and Baker, 1983), the amino acid composition of the nectar (Baker and Baker, 1975) and the rate of nectar production (Heinrich, 1976; Brink and deWet, 1980; Pleasants, 1981; Cruden, Hermann-Parker and Peterson, 1982). In this paper I examine some of the nectar properties, primarily nectar production rate (hereafter abbreviated NPR) and sugar concentration of Ipomopsis aggregata, a hummingbird-pollinated species. The purposes of the paper are 1) to describe how nectar production rate and sugar concentration are influenced by flower age, time of day, point in the flowering season, weather conditions and removal of nectar by pollinators and nectar robbers and discuss the ' Received for publication 3 December 1982revision accepted 18 August 1983. I would like to thank Bob Neely, Renee Neely, Mark Pelham, Paul Rich, Martha Pleasants and Barbara Pleasants for assisting in collecting the data for this study. The paper benefitted from discussions with David Inouye, Nick Waser Graham Pyke, Larry Wolf and Mike Zimmerman. This study was supported by NSF Grant DEB-8 1 1 1027 and an Iowa State University Minigrant. potential effiect of this on pollinator foraging patterns and possible advantages for the plant, and 2) to evaluate these influences on nectar production in terms of our ability to accurately characterize the NPR and sugar concentration of plants. A plant's NPR is considered to be a trait which is as important a part of its pollinator syndrome as flower color, odorS etc. It is common to use 24-hr NPR to explain the attractiveness of diffierent species to pollinators (Heinrich? 1976; Brown and Kodric-Brown, 1979; Southwick, Loper and Sadwick, 1981; Pleasants, 1981) or to examine ecotypic variation within a species (Brink and deWet, 1980). In general, 24-hr production is measured by bagging flowers for 24 hr and measuring the amount of accumulated nectar. But there are some questions concerning the validity of this measure. First, is the secretion rate altered by the presence of accumulated nectar? Second, is nectar sugar reabsorbed if accumulated nectar is not removed? Serious errors may occur when comparingthe 24-hrproduction of species which differ in this regard. There are also some questions about characterizing the NPR of a plant by sampling at one point in time. First, how are the estimates of NPR affected by whether the measurements were done on an overcast day or a sunny day? Second, is the

Continuity of solutions of a singular parabolic equation

Abstract: which is of parabolic divergence form since $’ 3 0 a.e. However it is the solution u of (0.1) which will be continuous, while the solution u of (0.2) need not be. In certain physical applications u corresponds to temperature while u is the enthalpy. The difficulty in the analysis of this equation, written in the form (0.2), stems from the fact that c#+ need not be bounded or bounded away from zero. Thus the equation may be of degenerate or singular parabolic type. As particular cases of the equations covered by our results we mention the three model problems

Nectar production rates of Asclepias quadrifolia: causes and consequences of individual variation

Abstract: The causes and reproductive consequences of individual variation in nectar production rates within a population of Asclepias quadrifolia were investigated. Two parameters were correlated with nectar production rate per flower: the root weight of the plant and the number of flowers in the inflorescence (umbel). Nectar production increased with increasing root weight but levelled off after a root size of about 3 g was reached. Nectar production decreased with increasing umbel size, but only for umbels that were greater than average size. A total of 57% of the variance in individual nectar production could be explained by these two variables with root weight accounting for 67% of the explained variance. Root weight is a good indicator of a plant's energetic status, indicating the importance of available energy in determining quantity of nectar produced. About 30% of the energy devoted to flowering is utilized in nectar production. Nectar production was significantly correlated with the male component of reproductive fitness, pollinaria removal, but not with the female component, pollinia insertion. Since pod production is limited by resource availability rather than the number of pollinia insertions, nectar production in A. quadrifolia is most closely associated with the maximization of the male function.

A Logical and Empirical Analysis of Current Practice in Classifying Students as Handicapped

Abstract: The major criterion for classification systems is that students said to evidence any specific handicapping condition must demonstrate at least one universal and one specific characteristic. We conducted two investigations, using the category “learning disabilities” as an example, to examine the extent to which this criterion is met. In the first study, we demonstrated that 85% of 248 3rd-, 5th-, and 12th- grade students identified as normal could be classified as learning disabled. In a second investigation, we contrasted low-achieving students enrolled in regular fourth-grade classes with students labeled as learning disabled (LD). Analysis of these data indicated that 88% of the low-achieving sample could be identified as LD and that 4% of the LD sample did not meet any of the criteria for classification as LD. We found no specific characteristics that differentiated the groups.Implications for classification practices in general and for serving students who are failing in school are discussed.

Hamilton-Jacobi Theory and the Quantum Action Variable

Abstract: A quantum action variable is defined in the context of a quantum Hamilton-Jacobi theory. The action variable can be used to find the exact bound-state energy levels of a quantum system without solving an equation of motion for the system wave functions.

A Diffusion Model with a Concentration-Dependent Diffusion Coefficient for Describing Water Movement in Legumes During Soaking

Abstract: A mathematical model based on Fick's diffusion equation with a concentration-dependent diffusion coefficient was proposed to describe the absorption of water by legumes. The equation was solved by using a numerical scheme. Parameter study was performed. The model is capable of predicting sigmoidal-shaped water uptake curves common to many legumes. Differences are discussed between the surface resistance boundary condition used in this study and the radiation boundary condition widely used for dehydration calculations. The validity of using the proposed model to described the water uptake of legumes was verified by the good fit between the experimental and theoretical curves.

Half-fringe photoelasticity: A new approach to whole-field stress analysis

Abstract: This paper presents a new method for whole-field stress analysis based on a symbiosis of two techniques—classical photoelasticity and modern digital image analysis. The resulting method is called ‘half-fringe photoelasticity (HFP)’. Classical photoelasticity demands materials with high birefringence, which leads to extensive use of plastics as model materials. Since the behavior of these materials is often different from that of the prototype materials, their use distorts the similitude relationships. In many contemporary problems this distortion is untenable. HFP offers a way out of this dilemma. It permits materials and loads to be chosen so that no more than one half of a fringe order appears in the area of interest. Thus, for example, glass, which behaves linearly up to high stress levels and over a wide range of temperatures, could be used as model material. Alternatively, models from polymeric materials could be used under very low load in order to stay within the linear part of the stress-strain diagram and to prevent large deformations. The half-fringe-photoelasticity system, which is described here, utilizes the resulting low levels of birefringence for effective stress analysis. This paper describes the system. It outlines a calibration routine and illustrates its application to two simple problems using glass models.

Influence of Temperature, pH, Water Activity and Antifungal Agents on Growth of Aspergillus flavus and A. parasiticus

Abstract: Effect of temperature, pH, water activity, and nine antifungal agents on growth of Aspergillus flavus and A. parasiticus was determined on Sabouraud-Dextrose Agar and on corn. Maximal growth of the two molds occurred at 33°C, the highest temperature used, pH of 5.0 and aw of 0.99. At 15°C, growth was observed at aw of 0.95 but not 0.90. Slight growth was observed at an aw, of 0.85 at 27°C and 33°C. Nine antifungal agents (Botran, Orthocide, Poly-ram 80, Topsin-M, Thiram, Imazalil, sodium propionate, sodium sulfite and DDVP) were tested for inhibition of growth. Activity of the antifungals increased as the aw was decreased. All antifungals showed inhibitory activity, but Imazalil and DDVP were the most effective agents at the lowest concentrations.

Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

Abstract: A refractive index and absorption detector for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded.

Self-attention and self-report: The “veridicality” hypothesis

Abstract: Wicker (1969) summarized the state of the art in the area of attitude/behavior consistency by suggesting that attitude measures are often only slightly related to overt behaviors. Since that time literally hundreds of studies have been conducted dealing with the question of how the predictive validity of self-assessment can be improved-above the 30 figure that Wicker suggested represents the typical upper limit of correlations between self-reported attitudes and behavior. This article deals with perhaps one of the simplest factors that does appear to be related to accurate self-assessment: internal focus of attention. Research in the area of self-awareness theory is discussed, leading to the conclusion that assessments of various aspects of the self, including attitudes, cognitions, and affective and somatic states, usually are more accurate when they are made by a respondent whose attention is self-directed. By the same token, overt behavior also tends to be more consistent with previously expressed attitudes when it occurs under conditions conducive to self-focus. In discussing this research, it is suggested that self-awareness promotes accuracy in two ways: (a) It focuses the respondent's attention more carefully on those aspects of the self made relevant by the instrument and (b) it increases the person's motivation to report accurately on those self-dimensions. It is also suggested, however, that this latter factor can sometimes work against consistency. In this regard, a variety of situations are discussed in which motives that may conflict with the desire to report accurately, such as ego-protectiveness, are also enhanced by self-focused attention. Finally, a number of empirical questions are presented as guidelines for future research.

Regulation, genetics, and properties of adenylosuccinate synthetase: a review.

Abstract: Publisher Summary This chapter discusses regulation, genetics, and the properties of adenylosuccinate synthetase. Adenylosuccinate formed by adenylosuccinate synthetase is cleaved by adenylosuccinate lyase to form adenosine monophosphate (AMP). The two-step conversion of inosine 5' monophosphate (IMP) to AMP is similar to both the conversion of citrulline to arginine, which involves formation of argininosuccinate as an intermediate, and formation of 5-amino-imidazole 4-carboxamide ribonucleotide from 5-aminoimidazole 4-carboxylate ribonucleotide as part of IMP biosynthesis. Adenylosuccinate lyase is a dual-function enzyme catalyzing the cleavage of both adenylosuccinate and 5-aminoimidazole 4- N -succinocarboxamide ribonucleotide. The determination of the enzymatic activity of adenylosuccinate synthetase is most easily accomplished by observing the increase in absorbance at 280 nm, accompanying the conversion of IMP to adenylosuccinate. The most versatile system for the synthetase assay utilizes endogenous or added lyase and adenylate kinase to trap the adenylosuccinate into adenosine diphosphate and adenosine monophosphate. Adenylosuccinate synthetase is subject to feedback and product inhibition by AMP, adenylosuccinate, guanosine diphosphate, and guanosine monophosphate.

Hydrogen-induced cracking in 4340-type steel: Effects of composition, yield strength, and H2 pressure

Abstract: Measurements of the threshold stress intensity for hydrogen-induced crack extension,Kth at room temperature were made on bolt-loaded WOL specimens of a commercial 4340 steel and of laboratory heats in which the bulk concentrations of manganese, silicon, phosphorus, and sulfur were varied. The hydrogen pressure was varied from 200 to 1600 torr (~0.03 to 0.22 MPa), and the yield strengths were varied from ~170 to 270 ksi (~1200 to 1900 MPa). Measurements ofKIc in air were also made as a function of composition and yield strength. Significant differences betweenKIc in air andKth in H2 were found only in steels containing added Mn or Si; these elements are believed to promote segregation of phosphorus and sulfur to austenite grain boundaries. TheKth values were uniquely related to the percentage of intergranular fracture and also to a parameter containing the calculated maximum hydrogen concentration and the bulk concentrations of manganese, silicon, phosphorus, and sulfur. In a high purity steel free of manganese and silicon theKth was lower thanKIc only at yield strengths greater than 200 ksi (1400 MPa). The results are consistent with an additive reduction in cohesive strength by hydrogen and metalloid impurities. It is shown that theKth depends on hydrogen fugacity, yield strength, and grain boundary purity(i.e., cohesive strength).

Solute segregation and hydrogen-induced intergranular fracture in an alloy steel

Abstract: Hydrogen-induced intergranular fracture of laboratory heats of a 3.5 Ni-1.7 Cr steel doped with P, Sn, or Sb and having a yield strength of 840 MPa and a prior austenite grain size of 120 μm has been compared with that of an undoped steel at a hydrogen pressure of 0.17 MPa (1.68 atm). The intergranular concentrations of the impurities were controlled by varying the time of aging at 480 °C. Cracking of the undoped steel tested in hydrogen occurred along martensitic lath boundaries at high stresses. However, the susceptibility of the doped steels to hydrogen-induced intergranular cracking increased precipitously with impurity concentration. The susceptibility was measured in terms of the threshold stress intensity Kthfor the first detectable crack extension in precracked specimens and in terms of the threshold stress σth for microcrack formation in notched specimens. A comparison between the intergranular strength in hydrogen and in air revealed that absorption of hydrogen produced a profound intergranular weakening when the grain boundaries contained even a small amount of a segregated embrittling element. The relative embrittling potencies of P, Sn, and Sb in hydrogen gas were the same as in air. The combined effects of hydrogen and the impurities in reducing intergranular cohesion are discussed in terms of a newly proposed dynamic model which takes into account the accumulation of hydrogen ahead of a moving microcrack.

Job and life satisfactions: a causal analysis of their relationships.

Abstract: The article discusses the nature of the relationship between work and nonwork satisfactions. It employs longitudinal data to overcome some of the inaccuracies of the earlier studies. The literature...

The life satisfaction index: a methodological and theoretical critique.

Abstract: The Life Satisfaction Index A (LSIA) was examined by factor analytic techniques. The data do not support the original conceptual framework of Neugarten and her colleagues. Although the results indicate a strong need for caution, there is evidence of an alternative interpretation of the LSIA that has a degree of consistency across racial and gender categories. In addition, these findings raise implicit questions about prior research using the LSIA and demonstrate the importance of making comprehensive, critical evaluations of scales with complex theoretical origins.