Showing papers by "University of Central Florida published in 2000"

Understanding the Customer Base of Service Providers: An Examination of the Differences Between Switchers and Stayers

Abstract: Creating and maintaining customer loyalty has become a strategic mandate in today’s service markets. Recent research suggests that customers differ in their value to a firm, and therefore customer retention and loyalty-building efforts should not necessarily be targeted to all customers of a firm. Given these sentiments, it is becoming increasingly necessary for firms to have a thorough understanding of their customer base. Yet current knowledge is limited in providing insights to firms regarding the differences within their customer base. This research comprises two studies in which the authors examine the differences among internal customer groups in a service industry. As theory suggests and as is empirically validated here, customers who have switched service providers because of dissatisfaction seem to differ significantly from other customer groups in their satisfaction and loyalty behaviors. The findings offer some interesting implications for both marketing theory and practice.

Measuring Team Knowledge

Abstract: Multioperator tasks often require complex cognitive processing at the team level. Many team cognitive processes, such as situation assessment and coordination, are thought to rely on team knowledge. Team knowledge is multifaceted and comprises relatively generic knowledge in the form of team mental models and more specific team situation models. In this methodological review paper, we review recent efforts to measure team knowledge in the context of mapping specific methods onto features of targeted team knowledge. Team knowledge features include type, homogeneity versus heterogeneity, and rate of knowledge change. Measurement features include knowledge elicitation method, team metric, and aggregation method. When available, we highlight analytical conclusions or empirical data that support a connection between team knowledge and measurement method. In addition, we present empirical results concerning the relation between team knowledge and performance for each measurement method and identify research and methodological needs. Addressing issues surrounding the measurement of team knowledge is a prerequisite to understanding team cognition and its relation to team performance and to designing training programs or devices to facilitate team cognition.

When Member Homogeneity is Needed in Work Teams: A Meta-Analysis

Abstract: A meta-analytic integration of 57 effect sizes from 13 studies (567 teams, 2,258 participants) was performed to determine if groups that are homogeneous with respect to gender, ability level, and personality achieve higher levels of performance than teams that are heterogeneous on these attributes. Although individual studies often show marked differences between homogeneous and heterogeneous groups, the results of this integration show the combined effect sizes of these studies to be small, though not significant, in favor of heterogeneous groups. It appears that the significant effects found in many of the included studies can be attributed to the type and difficulty of the task used in the investigation. Implications for team construction are discussed.

Research Report: The Role of Behavioral Modeling in Computer Skills Acquisition: Toward Refinement of the Model

Abstract: Recent empirical work by Compeau and Higgins (1995) investigated the role of behavioral modeling training in the development of computer skills. Their efforts have provided insight into our understanding of the role of computer self-efficacy (CSE) and behavioral modeling (BM) techniques with regard to training effectiveness. Contrary to their expectations, however, several of the hypothesized relationships were not supported, especially those relating to outcome expectancy. In this paper, an empirically derived model of the CSE construct proposed by Marakas, Yi, and Johnson (1998) is offered to highlight potential theoretical, methodological, and measurement issues which may have contributed to or exacerbated the unexpected results obtained in the Compeau and Higgins study. The empirical work contained herein is intended to both replicate and extend the work of Compeau and Higgins and to assist in resolving several key issues left unsettled by their seminal work in this area.

Optical Versus Video See-Through Head-Mounted Displays in Medical Visualization

Abstract: We compare two technological approaches to augmented reality for 3-D medical visualization: optical and video see-through devices. We provide a context to discuss the technology by reviewing several medical applications of augmented-reality re search efforts driven by real needs in the medical field, both in the United States and in Europe. We then discuss the issues for each approach, optical versus video, from both a technology and human-factor point of view. Finally, we point to potentially promising future developments of such devices including eye tracking and multifocus planes capabilities, as well as hybrid optical/video technology.

Dynamic evolution of plant mitochondrial genomes: mobile genes and introns and highly variable mutation rates.

Abstract: We summarize our recent studies showing that angiosperm mitochondrial (mt) genomes have experienced remarkably high rates of gene loss and concomitant transfer to the nucleus and of intron acquisition by horizontal transfer. Moreover, we find substantial lineage-specific variation in rates of these structural mutations and also point mutations. These findings mostly arise from a Southern blot survey of gene and intron distribution in 281 diverse angiosperms. These blots reveal numerous losses of mt ribosomal protein genes but, with one exception, only rare loss of respiratory genes. Some lineages of angiosperms have kept all of their mt ribosomal protein genes whereas others have lost most of them. These many losses appear to reflect remarkably high (and variable) rates of functional transfer of mt ribosomal protein genes to the nucleus in angiosperms. The recent transfer of cox2 to the nucleus in legumes provides both an example of interorganellar gene transfer in action and a starting point for discussion of the roles of mechanistic and selective forces in determining the distribution of genetic labor between organellar and nuclear genomes. Plant mt genomes also acquire sequences by horizontal transfer. A striking example of this is a homing group I intron in the mt cox1 gene. This extraordinarily invasive mobile element has probably been acquired over 1,000 times separately during angiosperm evolution via a recent wave of cross-species horizontal transfers. Finally, whereas all previously examined angiosperm mtDNAs have low rates of synonymous substitutions, mtDNAs of two distantly related angiosperms have highly accelerated substitution rates.

Performance Measurement in U.S. Counties: Capacity for Reform

Abstract: This study examines the capacity of U.S. counties to undertake performance measurement. Based on a national survey of counties with populations over 50,000, the authors address the following questions: To what extent do counties implement performance measurement? Which capacities must be present for different levels of implementation and success? What can counties do to increase their capacity for performance measurement? And, what is the effect of county structure and functions on the use of performance measurement? This study finds that the success of performance measurement is greatly affected by counties' underlying organizational capacities.

Teamwork in multi-person systems: a review and analysis.

Abstract: As the scope and complexity of modern task demands exceed the capability of individuals to perform, teams are emerging to shoulder the burgeoning requirements Accordingly, researchers have striven to understand and enhance human performance in team settings The purpose of this review is to summarize that research, from the theoretical underpinnings that drive it, to the identification of team-level elements of success, to the methodologies and instruments that capture and measure those characteristics Further specified are three important avenues to creating successful teams: team selection, task design and team training In other words, one can select the right people, provide them with a task engineered for superior performance and train them in the appropriate skills to accomplish that task Under task design, new technologies and automation are examined that both support and impede team functioning Finally, throughout are provided critical remarks about what is known about teamwork and what is needed to be known to move the science and practice of team performance forward The paper concludes with the identification of team issues that require further investigation

Duration and Exposure to Virtual Environments: Sickness Curves During and Across Sessions

Abstract: Although simulator sickness is known to increase with protracted exposure and to diminish with repeated sessions, limited systematic research has been performed in these areas. This study reviewed the few studies with sufficient information available to determine the effect that exposure duration and repeated exposure have on motion sickness. This evaluation confirmed that longer exposures produce more symptoms and that total sickness subsides over repeated exposures. Additional evaluation was performed to investigate the precise form of this relationship and to determine whether the same form was generalizable across varied simulator environments. The results indicated that exposure duration and repeated exposures are significantly linearly related to sickness outcomes (duration being positively related and repetition negatively related to total sickness). This was true over diverse systems and large subject pools. This result verified the generalizability of the relationships among sickness, exposure duration, and repeated exposures. Additional research is indicated to determine the optimal length of a single exposure and the optimal intersession interval to facilitate adaptation.

A neural network-based smart antenna for multiple source tracking

Abstract: This paper considers the problem of multiple-source tracking with neural network-based smart antennas for wireless terrestrial and satellite mobile communications. The neural multiple-source tracking (N-MUST) algorithm is based on an architecture of a family of radial basis function neural networks (RBFNN) to perform both detection and direction of arrival (DOA) estimation. The field of view of the antenna array is divided into spatial angular sectors, which are in turn assigned to a different pair of RBFNNs. When a network detects one or more sources in the first stage, the corresponding second stage network(s) are activated to perform the DOA estimation. Simulation results are performed to investigate the performance of the algorithm for various angular separations, with sources of random relative signal-to-noise ratio and when the system suffers from Doppler spread.

Conductivity and Water Uptake of Aromatic‐Based Proton Exchange Membrane Electrolytes

Abstract: Water uptake and proton conductivity as a function of temperature were determined for three aromatic-based, sulfonic acid-bearing polymers, plus the perfluoroalkyl sulfonic acid Nafion{reg_sign} 117. Water uptake of submerged, equilibrated samples ranged from less than five water molecules per acid group for a high equivalent weight, sulfonated polyethersulfone to almost fifty waters per acid for a low equivalent weight, sulfonated polyetheretherketone. The most conductive aromatic-based polymer, sulfonated polyphenylquinoxaline (S-PPQ), had a room temperature conductivity of 9.8 x 10{sup {minus}3} S/cm, about an order of magnitude less than that of a perfluoroalkyl sulfonic acid under identical conditions. The slope of the S-PPQ Arrhenius conductivity plot was sufficiently steep that at 180 C, the proton conductivity, 1.3 x 10{sup {minus}1} S/cm, was only a factor of two lower than that of Nafion under similar conditions. The lower conductivity of the aromatic-based sulfonic acid polymers can be attributed to chain rigidity, lack of ion channels, and lower acidity.

Forgiveness and fundamentalism: reconsidering the relationship between correctional attitudes and religion

Abstract: Although research typically has failed to establish a relationship between religious affiliation and correctional attitudes, recent assessments have revealed that fundamentalist Christians tend to be more punitive than are nonfundamentalists. These studies have advanced our understanding considerably, but their conceptualization of religion and correctional attitudes has been limited. Using a statewide survey, the present study demonstrates that compassionate as well as fundamentalist aspects of religious beliefs are related to public correctional preferences. Further, our results reveal that religion influences support for rehabilitation as well as punitiveness. These findings suggest the need for scholars to think more broadly about the role of religion in criminology.

Synthesis of new two-photon absorbing fluorene derivatives via Cu-mediated Ullmann condensations

Abstract: The Ullmann amination reaction was utilized to provide access to a number of fluorene analogues from common intermediates, via facile functionalization at positions 2, 7, and 9 of the fluorene ring. Through variation of amine or iodofluorene derivative, analogues bearing substitutents with varying electron-donating and electron-withdrawing ability, e.g., diphenylamino, bis-(4-methoxyphenyl)amine, nitro, and benzothiazole, were synthesized in good yield. The novel fluorene derivatives were fully characterized, including absorption and emission spectra. Didecylation at the 9-position afforded remarkably soluble derivatives. Target compounds 4, 5, and 9 are potentially useful as fluorophores in two-photon fluorescence microscopy. Their UV-vis spectra display desirable absorption in the range of interest suitable for two-photon excitation by near-IR femtosecond lasers. Preliminary measurements of two-photon absorption indicate the derivatives exhibit high two-photon absorptivity, affirming their potential as two-photon fluorophores. For example, using a 1,210 nm femtosecond pump beam, diphenylaminobenzothiazolylfluorene 4 exhibited nondegenerate two-photon absorption, with two-photon absorptivity (delta) of ca. 820 x 10(-50) cm(4) s photon(-1) molecule(-1) at the femtosecond white light continuum probe wavelength of 615 nm.

Near-IR Two-Photon Photoinitiated Polymerization Using a Fluorone/Amine Initiating System

Abstract: Emerging device technologies such as microelectromechanical systems and integrated sensors are placing increased demands on the development of materials processing and fabrication techniques.1,2 In response, the characteristic three-dimensional (3-D) spatial resolution of the simultaneous two-photon absorption (2PA) process is being harnessed for 3-D photoinitiated polymerization and microlithography. This is facilitated by the unique properties associated with simultaneous absorption of two-photons relative to single-photon mediated processes. There have been a limited number of reports of two-photon photopolymerization of commercial acrylate monomer systems, pre-formulated with UV photoinitiators.3-6 Efficient two-photon absorbing compounds based on phenylethenyl constructs bearing electron-donating and/ or electron-withdrawing moieties have been reported.7 Among these are electron-rich derivatives that have been found to undergo a presumed two-photon induced electron transfer to acrylate monomers8 or proposed fluorescence energy transfer to a photoinitiator,9 initiating polymerization. The reportedly efficient twophoton photoinitiators, although more photosensitive than previously studied UV photoinitiators, are not commercially available and require rather involved syntheses. Thus, the practicality of their broader use is questionable. Herein, we report the near-IR two-photon induced polymerization of (meth)acrylate monomers using a commercially available photoinitiator system based on a visible light-absorbing dye. Multiphoton absorption has been defined as simultaneous absorption of two or more photons via virtual states in a medium.10 The process requires high peak power, which is available from pulsed lasers. A major feature that distinguishes single-photon absorption from two-photon absorption is the rate of energy (light) absorption as a function of incident intensity. In single or onephoton absorption, the rate of light absorption is directly proportional to the incident intensity (dw/dt R I), while in 2PA, the rate of light absorption is proportional to the square of the incident intensity (dw/dt R I2).10,11 The quadratic, or nonlinear, dependence of two-photon absorption as a function of light intensity has substantial implications. For example, in a medium containing one-photon absorbing chromophores, significant absorption occurs all along the path of a focused beam of suitable wavelength light, leading to outof-focus absorption and associated processes. In a two-photon process, however, negligible absorption occurs except in the immediate vicinity of the focal point of a light beam of appropriate energy. This allows spatial resolution about the beam axis, as well as radially, and is the principle basis for two-photon fluorescence imaging.12 In 2PA, the final state reached has the same parity as the initial state, while in single-photon absorption the parity is opposite as given by dipole selection rules. However, in most solids and complicated molecules, the parity can become mixed in “bands”. In such molecules (such as the fluorone dye used in this report) two near-IR photons achieve essentially the same electronically excited singlet state as would be obtained via resonant singlephoton absorption at or near λmax. These molecules are expected to display identical photochemical and photophysical behavior when excited by one or 2PA. If such species return to the ground state via emission, fluorescence results with the energy of emission greater than the energy of the individual photons involved in the 2PA excitation. It is widely believed that a “revolution” in miniaturization, particularly in the field of microelectromechanical systems (MEMS), is underway. It is projected that the design and manufacturing technology that will be developed for MEMS may rival, or even surpass, the far-reaching impact of ICs on society and the world’s economy. At the forefront of techniques being explored for 3-D spatially resolved materials imaging and processing are methods based on 2PA. The use of longer wavelength light as the excitation source leads to deeper penetration depths than possible with conventional UV or visible excitation techniques. Since the absorption/excitation is confined to the focal volume in the 2PA process, there will be virtually no out-of-focus excitation/reaction, facilitating 3-D spatial control of the process. We conducted two-photon initiated polymerization at 775 nm via direct excitation of a commercially available dye (5,7-diiodo3-butoxy-6-fluorone, H-Nu 470) in the presence of an arylamine, † Department of Chemistry. § School of Optics/Center for Research and Education in Optics and Lasers. (1) See, for example: Belfield, K. D.; Abdelrazzaq, F. B. J. Polym. Sci., Part A: Polym. Chem. 1997, 35, 2207. (2) See, for example: Belfield, K. D.; Abdelrazzaq, F. B. Macromolecules 1997, 30, 6985. (3) Strickler, J. H.; Webb, W. W. Opt. Lett. 1991, 16, 1780. (4) Maruo, S.; Nakamura, O.; Kawata, S. Opt. Lett. 1997, 22, 132. (5) Borisov, R. A.; Dorojkina, G. N.; Koroteev, N. I.; Kozenkov, V. M.; Magnitskii, S. A.; Malakhov, D. V.; Tarasishin, A. V.; Zheltikov, A. M. Appl. Phys. B 1998, 67, 765. (6) Borisov, R. A.; Dorojkina, G. N.; Koroteev, N. I.; Kozenkov, V. M.; Magnitskii, S. A.; Malakhov, D. V.; Tarasishin, A. V.; Zheltikov, A. M. Laser Phys. 1998, 8, 1105. (7) Albota, M.; Beljonne, D.; Bredas, J.-L.; Ehrlich, J. E.; Fu, J.-Y.; Heikal, A. A.; Hess, S. E.; Kogej, T.; Levin, M. D.; Marder, S. R.; McCord-Maughon, D.; Perry, J. W.; Rockel, H.; Rumi, M.; Subramaniam, G.; Webb, W. W.; Wu, X.-L.; Xu, C. Science 1998, 281, 1653. (8) Cumpston, B. H.; Ananthavel, S. P.; Barlow, S.; Dyer, D. L.; Ehrlich, J. E.; Erskine, L. L.; Heikal, A. A.; Kuebler, S. M.; Lee, I.-Y. S.; McCordMaughon, D.; Qin, J.; Rockel, H.; Rumi, M.; Wu, X. L.; Marder, S. R.; Perry, J. W. Nature 1999, 398, 51. (9) Joshi, M. P.; Pudavar, H. E.; Swiatkiewicz, J.; Prasad, P. N.; Reinhardt, B. A. Appl. Phys. Lett. 1999, 74, 170. (10) Goeppert-Mayer, M. 1931, 9, 273. (11) Kershaw, S. In Characterization Techniques and Tabulations for Organic Nonlinear Optical Materials; Kuzyk, M. G., Dirk, C. W., Eds.; Marcel Dekker: New York, 1998; Chapter 7. (12) Denk, W.; Strickler, J. H.; Webb, W. W. Science 1990, 248, 73. Figure 1. Direct two-photon photoinitiated polymerization at 775 nm using a fluorone 2PA photoinitiator adapted from the single-photon mechanism.16 1217 J. Am. Chem. Soc. 2000, 122, 1217-1218

Organizational learning practices in the project management environment

Abstract: Describes the organizational learning practices in a project management environment to ensure project quality. The project management and organizational learning processes are described using the plan‐do‐study‐act (PDSA) cycle from quality management. Data from a survey of practicing project managers support the theory that organizational learning practices are associated with project knowledge, which is associated with project performance. Project knowledge is associated with learning that occurs both within and across projects. Managers can use this research to develop specific strategies to increase project success through learning. Researchers can use the results to understand how learning occurs in project environments. Implications are provided for project managers to use in focusing the learning activities of a project team.

Standardizing the nomenclature of Martian impact crater ejecta morphologies

Abstract: The Mars Crater Morphology Consortium recommends the use of a standardized nomenclature system when discussing Martian impact crater ejecta morphologies. The system utilizes nongenetic descriptors to identify the various ejecta morphologies seen on Mars. This system is designed to facilitate communication and collaboration between researchers. Crater morphology databases will be archived through the U.S. Geological Survey in Flagstaff, where a comprehensive catalog of Martian crater morphologic information will be maintained.

Monitoring head/eye motion for driver alertness with one camera

Abstract: We describe a system for analyzing human driver alertness. It relies on optical flow and color predicates to robustly track a person's head and facial features. Our system classifies rotation in all viewing directions, detects eye/mouth occlusion, detects eye blinking, and recovers the 3D gaze of the eyes. We show results and discuss how this system can be used for monitoring driver alertness.

Tourism and Terrorism: A Quantitative Analysis of Major Terrorist Acts and Their Impact on Tourism Destinations:

Abstract: Since before the end of the Cold War, terrorism acts have had major effects on tourism destinations. As a result, the ‘shadowy, mobile, and unpredictable’ forces of terrorism are becoming an unfortunate part of the travel and tourism landscape. Few can forget the explosion that killed three in Paris in 1986, the home-made pipe bomb in Tel Aviv in 1990, the November 1997 massacre of 58 tourists at Luxor's Temple of Hatshepsut in Egypt, and the Kenyan and Tanzanian US Embassy truck bombings killing 263 in August 1998. This paper provides a quantitative analysis of major terrorism events around the world during 1985–98, classified by date, location, victims, weapons used, severity of damage, motive, effect on tourism demand, and length of effect. The analysis is followed by a summary and conclusions about the magnitude of the impact of these events on host destinations and the tourism industry worldwide.

Returns to returning

Abstract: We examine the labor market performance of return migrants using the Hungarian Household Panel Survey. Two distinct selection issues are considered in the estimation of the earnings equation; we implement a natural method using MLE. The result that there is a “premium” to work experience abroad for women is robust across the models we considered. For men, the return to working abroad is not generally significant.

Two estimators of the mean of a counting process with panel count data

Abstract: We study two estimators of the mean function of a countingprocess based on “panel count data.” The setting for “panel count data” is one in which $n$ independent subjects, each with a counting process with common mean function, are observed at several possibly different times duringa study. Following a model proposed by Schick and Yu, we allow the number of observation times, and the observation times themselves, to be random variables. Our goal is to estimate the mean function of the counting process. We show that the estimator of the mean function proposed by Sun and Kalbfleisch can be viewed as a pseudo-maximum likelihood estimator when a non-homogeneous Poisson process model is assumed for the counting process. We establish consistency of both the nonparametric pseudo maximum likelihood estimator of Sun and Kalbfleisch and the full maximum likeli- hood estimator, even if the underlying counting process is not a Poisson process.We also derive the asymptotic distribution of both estimators at a fixed time $t$, and compare the resulting theoretical relative efficiency with finite sample relative efficiency by way of a limited Monte-Carlo study.

Stable expression of a biodegradable protein-based polymer in tobacco chloroplasts

Abstract: Bioelastic protein-based polymers (PBP) have several medical (prevention of post-surgical adhesions) and non-medical (biodegradable plastic) applications. This study compares expression levels of PBP genes (synthetic) integrated into the nuclear genome or the large single-copy (LSC) or inverted repeat (IR) region of the chloroplast genome in transgenic tobacco plants. Polymer transcripts accumulated up to 100-fold higher in the IR plants than in those of nuclear transgenic plants. Integration of foreign genes into all of the chloroplast genomes (homoplasmy) and higher levels of polymer transcripts were observed only in the IR and not in LSC transgenic plants. Expression of the polymer protein was further confirmed by Western blot analysis.

Flame recognition in video

Abstract: This paper presents an automatic system for fire detection in video sequences. There are many previous methods to detect fire, however, all except two use spectroscopy or particle sensors. The two that use visual information suffer from the inability to cope with a moving camera or a moving scene. One of these is not able to work on general data, such as movie sequences. The other is too simplistic and unrestrictive in determining what is considered fire, so that it can be used reliably only in aircraft dry bays. Our system uses color and motion information computed from video sequences to locate fire. This is done by first using an approach that is based upon creating a Gaussian-smoothed color histogram to determine the fire-colored pixels, and then using the temporal variation of pixels to determine which of these pixels are actually fire. Unlike the two previous vision-based methods for pre detection, our method is applicable to more areas because of its insensitivity to camera motion. Two specific applications not possible with previous algorithms are the recognition of fire in the presence of global camera motion or scene motion and the recognition of fire in movies for possible use in an automatic rating system. We show that our method works in a variety of conditions, and that it can automatically determine when it has insufficient information.