Showing papers by "University of Central Florida published in 2006"

Object tracking: A survey

Abstract: The goal of this article is to review the state-of-the-art tracking methods, classify them into different categories, and identify new trends. Object tracking, in general, is a challenging problem. Difficulties in tracking objects can arise due to abrupt object motion, changing appearance patterns of both the object and the scene, nonrigid object structures, object-to-object and object-to-scene occlusions, and camera motion. Tracking is usually performed in the context of higher-level applications that require the location and/or shape of the object in every frame. Typically, assumptions are made to constrain the tracking problem in the context of a particular application. In this survey, we categorize the tracking methods on the basis of the object and motion representations used, provide detailed descriptions of representative methods in each category, and examine their pros and cons. Moreover, we discuss the important issues related to tracking including the use of appropriate image features, selection of motion models, and detection of objects.

Transformational Leadership and Job Behaviors: The Mediating Role of Core Job Characteristics.

Abstract: Although the effects of transformational leadership on task performance and organizational citizenship behavior (OCB) are well-documented, the mechanisms that explain those effects remain unclear. We propose that transformational leadership is associated with the way followers view their jobs, in terms of Hackman and Oldham’s (1976) core job characteristics. Results of our study support a structural model whereby indirect effects supplement the direct effects of transformational leadership on task performance and OCB through the mechanisms of job characteristics, intrinsic motivation, and goal commitment. Additional analyses revealed that transformational leadership relationships were significantly stronger for followers who perceived highquality leader-member exchange.

The genome of the sea urchin Strongylocentrotus purpuratus.

Abstract: We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.

Visual attention detection in video sequences using spatiotemporal cues

Abstract: Human vision system actively seeks interesting regions in images to reduce the search effort in tasks, such as object detection and recognition. Similarly, prominent actions in video sequences are more likely to attract our first sight than their surrounding neighbors. In this paper, we propose a spatiotemporal video attention detection technique for detecting the attended regions that correspond to both interesting objects and actions in video sequences. Both spatial and temporal saliency maps are constructed and further fused in a dynamic fashion to produce the overall spatiotemporal attention model. In the temporal attention model, motion contrast is computed based on the planar motions (homography) between images, which is estimated by applying RANSAC on point correspondences in the scene. To compensate the non-uniformity of spatial distribution of interest-points, spanning areas of motion segments are incorporated in the motion contrast computation. In the spatial attention model, a fast method for computing pixel-level saliency maps has been developed using color histograms of images. A hierarchical spatial attention representation is established to reveal the interesting points in images as well as the interesting regions. Finally, a dynamic fusion technique is applied to combine both the temporal and spatial saliency maps, where temporal attention is dominant over the spatial model when large motion contrast exists, and vice versa. The proposed spatiotemporal attention framework has been applied on over 20 testing video sequences, and attended regions are detected to highlight interesting objects and motions present in the sequences with very high user satisfaction rate.

What type of leadership behaviors are functional in teams? A meta-analysis

Abstract: Despite the increased work on leadership in teams, there is a lack of integration concerning the relationship between leader behaviors and team performance outcomes. A framework depicting the relationship between leadership functions, specific leadership behaviors, and conditions which enable team performance was created. Using this framework, a meta-analysis was conducted to examine the relationship between leadership behavior in teams and behaviorally-based team performance outcomes. Results suggest the use of task-focused behaviors is moderately related to perceived team effectiveness and team productivity (.333, .203). Person-focused behaviors were related to perceived team effectiveness (.360), team productivity (.284), and team learning (.560). Sub-group analyses indicated that the specific leadership behaviors investigated were generally related to team performance outcomes. Most notably, empowerment behaviors accounted for nearly 30% of the variance in team learning. Finally, moderator analyses investigating the level of task interdependence were conducted. Study limitations, practical implications, and directions for research are also outlined.

Computer Gaming and Interactive Simulations for Learning: A Meta-Analysis.

Abstract: Substantial disagreement exists in the literature regarding which educational technology results in the highest cognitive gain for learners. In an attempt to resolve this dispute, we conducted a me...

An X-ray computed tomography imaging agent based on long-circulating bismuth sulphide nanoparticles

Abstract: Nanomaterials have become increasingly important in the development of new molecular probes for in vivo imaging, both experimentally and clinically. Nanoparticulate imaging probes have included semiconductor quantum dots, magnetic and magnetofluorescent nanoparticles, gold nanoparticles and nanoshells, among others. However, the use of nanomaterials for one of the most common imaging techniques, computed tomography (CT), has remained unexplored. Current CT contrast agents are based on small iodinated molecules. They are effective in absorbing X-rays, but non-specific distribution and rapid pharmacokinetics have rather limited their microvascular and targeting performance. Here we propose the use of a polymer-coated Bi(2)S(3) nanoparticle preparation as an injectable CT imaging agent. This preparation demonstrates excellent stability at high concentrations (0.25 M Bi(3+)), high X-ray absorption (fivefold better than iodine), very long circulation times (>2 h) in vivo and an efficacy/safety profile comparable to or better than iodinated imaging agents. We show the utility of these polymer-coated Bi(2)S(3) nanoparticles for enhanced in vivo imaging of the vasculature, the liver and lymph nodes in mice. These nanoparticles and their bioconjugates are expected to become an important adjunct to in vivo imaging of molecular targets and pathological conditions.

Rare earth nanoparticles prevent retinal degeneration induced by intracellular peroxides

Abstract: Photoreceptor cells are incessantly bombarded with photons of light, which, along with the cells' high rate of oxygen metabolism, continuously exposes them to elevated levels of toxic reactive oxygen intermediates (ROIs). Vacancy-engineered mixed-valence-state cerium oxide nanoparticles (nanoceria particles) scavenge ROIs. Our data show that nanoceria particles prevent increases in the intracellular concentrations of ROIs in primary cell cultures of rat retina and, in vivo, prevent loss of vision due to light-induced degeneration of photoreceptor cells. These data indicate that the nanoceria particles may be effective in inhibiting the progression of ROI-induced cell death, which is thought to be involved in macular degeneration, retinitis pigmentosa and other blinding diseases, as well as the ROI-induced death of other cell types in diabetes, Alzheimer's disease, atherosclerosis, stroke and so on. The use of nanoceria particles as a direct therapy for multiple diseases represents a novel strategy and suggests that they may represent a unique platform technology.

Freshmen adaptation to university life: Depressive symptoms, stress, and coping

Abstract: Attending a university for the first time can be a stressful experience for many new college students. This study examines the relationships among femininity and masculinity, depressive symptomatology, levels of stress, and the types of coping strategies used by college freshmen. Results of this study suggest that these variables were related uniquely for first-year college students. Masculinity and femininity significantly predicted problem-focused coping, and femininity significantly predicted emotion-focused coping. Further, the levels of family and college stress reported by college students, as well as their endorsement of avoidant coping, significantly predicted their levels of depressive symptoms. Overall, the results of this study suggest that understanding the relationships among the gender role, the levels of depressive symptomatology, and the levels of stress exhibited by college freshmen may be important in facilitating their transition and adjustment to university life.

Teamwork as an essential component of high-reliability organizations.

Abstract: Organizations are increasingly becoming dynamic and unstable. This evolution has given rise to greater reliance on teams and increased complexity in terms of team composition, skills required, and degree of risk involved. High-reliability organizations (HROs) are those that exist in such hazardous environments where the consequences of errors are high, but the occurrence of error is extremely low. In this article, we argue that teamwork is an essential component of achieving high reliability particularly in health care organizations. We describe the fundamental characteristics of teams, review strategies in team training, demonstrate the criticality of teamwork in HROs and finally, identify specific challenges the health care community must address to improve teamwork and enhance reliability.

Understanding team adaptation: a conceptual analysis and model.

Abstract: This endeavor provides a multidisciplinary, multilevel, and multiphasic conceptualization of team adaptation with theoretical roots in the cognitive, human factors, and industrial-organizational psychology literature. Team adaptation and the emergent nature of adaptive team performance are defined from a multilevel, theoretical standpoint. An input-throughput-output model is advanced to illustrate a series of phases unfolding over time that constitute the core processes and emergent states underlying adaptive team performance and contributing to team adaptation. The cross-level mixed-determinants model highlights team adaptation in a nomological network of lawful relations. Testable propositions, practical implications, and directions for further research in this area are also advanced.

A review of instruments measuring resilience.

Abstract: The objectives of the study were to evaluate the psychometric properties and appropriateness of instruments for the study of resilience in adolescents. A search was completed using the terms resilience and instruments or scales using the EBSCO database (CINAHL, PreCINAHL, and Academic Search Premier), MEDLINE, PsychINFO and PsychARTICLES, and the Internet. After instruments were identified, a second search was performed for studies reporting the psychometric development of these instruments. Using inclusion and exclusion criteria, six psychometric development of instrument studies were selected for a full review. A data extraction table was used to compare the six instruments. Two of the six instruments (Baruth Protective Factors Inventory [BPFI] and Brief-Resilient Coping Scale) lacked evidence that they were appropriate for administration with the adolescent population due to lack of research applications. Three instruments (Adolescent Resilience Scale [ARS], Connor-Davidson Resilience Scale, and Resilience Scale for Adults) had acceptable credibility but needed further study in adolescents. One instrument (Resilience Scale [RS]) was determined to be the best instrument to study resilience in the adolescent population due to psychometric properties of the instrument and applications in a variety of age groups, including adolescence. Findings of this review indicate that the RS is the most appropriate instrument to study resilience in the adolescent population. While other instruments have potential (e.g., ARS, BPFI) as they were tested in the adolescent and young adult populations, they lack evidence for their use at this time. An evaluation of the review and recommendations are discussed.

Elicitation using multiple price list formats

Abstract: We examine the properties of a popular method for eliciting choices and values from experimental subjects, the multiple price list format. The main advantage of this format is that it is relatively transparent to subjects and provides simple incentives for truthful revelation. The main disadvantages are that it only elicits interval responses, and could be susceptible to framing effects. We consider extensions to address and evaluate these concerns. We conclude that although there are framing effects, they can be controlled for with a design that allows for them. We also find that the elicitation of risk attitudes is sensitive to procedures, subject pools, and the format of the multiple price list table, but that the qualitative findings that participants are generally risk averse is robust. The elicitation of discount rates appear less sensitive to details of the experimental design.

Interagency Communication Networks During Emergencies: Boundary Spanners in Multiagency Coordination

Abstract: This article examines the problem of effective interagency communication among organizations and the role of information technologies to achieve effective communication and decision-making goals in emergencies. It explores what factors contribute to effective interorganizational communication and decision making and what factors inhibit their development. The theoretical framework draws on the literature of emergency communication and social capital, with a particular focus on communication and decision making under conditions of uncertainty. The study applies this framework to study the relationships that emerged among public, private, and non-profit organizations following the World Trade Center disaster on September 11, 2001, in New York City. The article indicates the importance of developing a strong communication system with other organizations before a disaster occurs to establish appropriate communication in which effective interagency coordination will take place at the time of a disaster.

Head-worn displays: a review

Abstract: Head-worn display design is inherently an interdisciplinary subject fusing optical engineering, optical materials, optical coatings, electronics, manufacturing techniques, user interface design, computer science, human perception, and physiology for assessing these displays. This paper summarizes the state-of-the-art in head-worn display design (HWD) and development. This review is focused on the optical engineering aspects, divided into different sections to explore principles and applications. Building on the guiding fundamentals of optical design and engineering, the principles section includes a summary of microdisplay or laser sources, the Lagrange invariant for understanding the trade-offs in optical design of HWDs, modes of image presentation (i.e., monocular, biocular, and stereo) and operational modes such as optical and video see-through. A brief summary of the human visual system pertinent to the design of HWDs is provided. Two optical design forms, namely, pupil forming and non-pupil forming are discussed. We summarize the results from previous design work using aspheric, diffractive, or holographic elements to achieve compact and lightweight systems. The applications section is organized in terms of field of view requirements and presents a reasonable collection of past designs

The Search for "Optimal" Cutoff Properties: Fit Index Criteria in Structural Equation Modeling

Abstract: . This study is a partial replication of L. Hu and P. M. Bentler's (1999) fit criteria work. The purpose of this study was twofold: (a) to determine whether cut-off values vary according to which model is the true population model for a dataset and (b) to identify which of 13 fit indexes behave optimally by retaining all of the correct models while simultaneously rejecting all of the misspecified models in a manner invariant across sample size and data distribution. The authors found that for most indexes the results do not vary depending on which model serves as the correct model. Furthermore, the search for an optimal cut-off value led to a new discovery about the nature of McDonald's measure of centrality and the root mean square error of approximation. Unlike all other indexes considered in this study, the cut-off value of both indexes actually decreases for incorrect models as sample size increases. This may suggest that power calculations are more likely to be optimal when based on those ind...

Challenges and advances in nanocomposite processing techniques

Abstract: Of late, nanotechnology seems to be rapidly thrusting its applications in all aspects of life including engineering and medicine. Materials science and engineering has experienced a tremendous growth in the field of nanocomposite development with enhanced chemical, mechanical, and physical properties. A wide array of research has been conducted in the processing of nanocomposites. Consolidation of these systems from loose particles to bulk free form entities has always been a challenge. To name a few, traditional consolidation techniques such as cold pressing and sintering at high temperatures, hot pressing, and hot isostatic pressing have strong limitations of not being able to retain the nanoscale grain size due to the excessive grain growth during processing. This article reviews in detail the results from numerous studies on various methods for manufacturing nanocomposites with improved properties and retained nanostructures. Both challenges and recent advances are discussed in detail in this review.

A multiview approach to tracking people in crowded scenes using a planar homography constraint

Abstract: Occlusion and lack of visibility in dense crowded scenes make it very difficult to track individual people correctly and consistently. This problem is particularly hard to tackle in single camera systems. We present a multi-view approach to tracking people in crowded scenes where people may be partially or completely occluding each other. Our approach is to use multiple views in synergy so that information from all views is combined to detect objects. To achieve this we present a novel planar homography constraint to resolve occlusions and robustly determine locations on the ground plane corresponding to the feet of the people. To find tracks we obtain feet regions over a window of frames and stack them creating a space time volume. Feet regions belonging to the same person form contiguous spatio-temporal regions that are clustered using a graph cuts segmentation approach. Each cluster is the track of a person and a slice in time of this cluster gives the tracked location. Experimental results are shown in scenes of dense crowds where severe occlusions are quite common. The algorithm is able to accurately track people in all views maintaining correct correspondences across views. Our algorithm is ideally suited for conditions when occlusions between people would seriously hamper tracking performance or if there simply are not enough features to distinguish between different people.

Does stock option-based executive compensation induce risk-taking? An analysis of the banking industry

Abstract: We investigate the relation between option-based executive compensation and market measures of risk for a sample of commercial banks during the period of 1992–2000. We show that following deregulation, banks have increasingly employed stock option-based compensation. As a result, the structure of executive compensation induces risk-taking, and the stock of option-based wealth also induces risk-taking. The results are robust across alternative risk measures, statistical methodologies, and model specifications. Overall, our results support a management risk-taking hypothesis over a managerial risk aversion hypothesis. Our results have important implications for regulators in monitoring the risk levels of banks.

Performance Appraisal, Performance Management and Improving Individual Performance: A Motivational Framework

Abstract: Performance appraisal has been the focus of considerable research for almost a century. Yet, this research has resulted in very few specific recommendations about designing and implementing appraisal and performance management systems whose goal is performance improvement. We believe that a reason for this is that appraisal research became too interested in measurement issues and not interested enough in ways to improve performance, although some recent trends in the area have begun moving the field in the right direction. We review these trends and their genesis, and propose a motivational framework as a means of integrating what we have learned and generating proposals for future research that focus on employee’s performance improvement.

Inter-Organizational Coordination in Extreme Events: The World Trade Center Attacks, September 11, 2001

Abstract: This paper addresses the problem of inter-organizational coordination in response to extreme events. Extreme events require coordinated action among multiple actors across many jurisdictions under conditions of urgent stress, heavy demand and tight time constraints. The problem is socio-technical in that the capacity for inter-organizational coordination depends upon the technical structure and performance of the information systems that support decision making among the participating organizations. Interactions among human managers, computers and organizations under suddenly altered conditions of operation are complex and not well understood. Yet, coordinating response operations to extreme events is an extraordinarily complex task for public and nonprofit managers. This paper will analyze the interactions among public, private and nonprofit organizations that evolved in response to the 11 September 2001 attacks, examining the relationships among organizations in terms of timely access to information and types of supporting infrastructure. The performance of the inter-organizational system is examined in the context of the events of 11 September 2001 from the theoretical perspective of complex adaptive systems. A model of auto-adaptation is proposed for implementation to improve inter- organizational performance in extreme events. This model is based on the concept of individual, organizational and collective learning in environments exposed to recurring risk, guided by a shared goal. Such a model requires public investment in the development of an information infrastructure that can support the intense demand for communication, information search, exchange and feedback that characterizes an auto-adaptive system.

Salvage logging, ecosystem processes, and biodiversity conservation.

Abstract: We summarize the documented and potential impacts of salvage logging—a form of logging that removes trees and other biological material from sites after natural disturbance. Such operations may reduce or eliminate biological legacies, modify rare postdisturbance habitats, influence populations, alter community composition, impair natural vegetation recovery, facilitate the colonization of invasive species, alter soil prop- erties and nutrient levels, increase erosion, modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity. These impacts can be assigned to three broad and interrelated effects: (1) altered stand structural complexity; (2) altered ecosystem processes and functions; and (3) altered populations of species and community composition. Some impacts may be different from or additional to the effects of traditional logging that is not preceded by a large natural disturbance because the conditions before, during, and after salvage logging may differ from those that characterize traditional timber harvesting. The potential impacts of salvage logging often have been overlooked, partly because the processes of ecosystem recovery after natural disturbance are still poorly understood and partly because potential cumulative effects of natural and human disturbance have not been well documented. Ecologically informed policies regarding salvage logging are needed prior to major natural disturbances so that when they occur ad hoc and crisis-mode decision making can be avoided. These policies should lead to salvage-exemption zones and limits on the amounts of disturbance-derived biological legacies (e.g., burned trees, logs) that are removed where salvage logging takes place. Finally, we believe new terminology is needed. The word salvage implies that something is being saved or recovered, whereas from an ecological perspective this is rarely the case.

Does crew resource management training work? An update, an extension, and some critical needs.

Abstract: Objective: This review provides the state of crew resource management (CRM) training evaluations since the E. Salas, C. S. Burke, C. A. Bowers, and K. A. Wilson (2001) review and extends it to areas beyond aviation cockpits. Some critical evaluation needs in CRM training are also covered. Background: Because of the purported success of CRM training in aviation, other high-consequence domains have begun to implement CRM training for their workforces. However, the true impact of CRM training in aviation and these other domains has yet to be determined. Method: Using D. L. Kirkpatrick's (1976) framework for evaluating training (i.e., reactions, learning, behavior, and organizational impact), we reviewed 28 published accounts of CRM training to determine its effectiveness within aviation, medicine, offshore oil production and maintenance, shipping/maritime, and nuclear power domains. Results: Findings indicate that CRM training generally produced positive reactions from trainees; however, the impact of traini...

Spitzer Spectral Observations of the Deep Impact Ejecta

Abstract: Spitzer Space Telescope imaging spectrometer observations of comet 9P/Tempel 1 during the Deep Impact encounter returned detailed, highly structured, 5- to 35-micrometer spectra of the ejecta. Emission signatures due to amorphous and crystalline silicates, amorphous carbon, carbonates, phyllosilicates, polycyclic aromatic hydrocarbons, water gas and ice, and sulfides were found. Good agreement is seen between the ejecta spectra and the material emitted from comet C/1995 O1 (Hale-Bopp) and the circumstellar material around the young stellar object HD100546. The atomic abundance of the observed material is consistent with solar and C1 chondritic abundances, and the dust-to-gas ratio was determined to be greater than or equal to 1.3. The presence of the observed mix of materials requires efficient methods of annealing amorphous silicates and mixing of high- and low-temperature phases over large distances in the early protosolar nebula.

RESILIENCE IN CHILDREN A Review of Literature With Implications for Education

Abstract: In spite of the most adverse circumstances, some children manage to survive and even thrive, academically and socially, into adulthood. A complex array of individual, family, and community factors has been identified that best explains resilience and lays the foundation for programs and interventions targeted at fostering the development and maintenance of resilience in at-risk youth. The literature is reviewed to identify and explain those factors, discuss their mutual interaction, and explain their implications for the creation of programs designed to support resilience in school-aged children.

Pushing the limits of mercury sensors with gold nanorods.

Abstract: The method presented here provides a direct way to determine mercury in tap water samples at the parts-per-trillion level. Its outstanding selectivity and sensitivity results from the well-known amalgamation process that occurs between mercury and gold. The entire procedure takes less than 10 min. No sample separation or sample preconcentration is required. The only step prior to mercury determination consists of mixing the water sample with a gold nanorod solution in sodium borohydride. The analytical figures of merit demonstrate precise and accurate analysis at the parts-per-trillion level. The limit of detection (6.6 × 10-13 g·L-1) shows excellent potential for monitoring ultralow levels of mercury in water samples.

Managing fire-prone forests in the western United States

Abstract: The management of fire-prone forests is one of the most controversial natural resource issues in the US today, particularly in the west of the country. Although vegetation and wildlife in these forests are adapted to fire, the historical range of fire frequency and severity was huge. When fire regimes are altered by human activity, major effects on biodiversity and ecosystem function are unavoidable. We review the ecological science relevant to developing and implementing fire and fuel management policies for forests before, during, and after wildfires. Fire exclusion led to major deviations from historical variability in many dry, low-elevation forests, but not in other forests, such as those characterized by high severity fires recurring at intervals longer than the period of active fire exclusion. Restoration and management of fire-prone forests should be precautionary, allow or mimic natural fire regimes as much as possible, and generally avoid intensive practices such as post-fire logging and planting.

The Effect of Type of Written Exercise on L2 Vocabulary Retention

Abstract: The present study used a within-subjects design to examine the effect of the type of written exercise on L2 vocabulary retention. Using input for the meaning and usage of the new words from a specially prepared minidictionary, university intensive English program students (n = 154) practiced target vocabulary in three types of written exercises conditions: one fill-in-the-blank exercise, three fill-in-the-blank exercises, and one original-sentence-writing exercise. An unannounced posttest using a modified version of the vocabulary knowledge scale tested the meaning of the word (L1 translation or L2 synonym) and usage of the word in a student-written sentence. A repeated measures ANOVA revealed that mean scores for the three exercise types were significantly different from each other, with words practiced under the three fill-in-the-blank exercises condition retained much better than those practiced under either of the other two exercise conditions. The findings suggest the important feature of a given L2 vocabulary exercise is not depth of word processing but number of word retrievals required. This result has implications for language teachers, curriculum designers, and, in particular, materials writers of traditional workbooks and CALL materials.