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- Title
- VIE-ing for the Position: An Examination of the Motivational Antecedents of Response Distortion.
- Creator
-
Mihm, David, Jentsch, Kimberly, Wang, Wei, Joseph, Dana, Piccolo, Ronald, University of Central Florida
- Abstract / Description
-
Faking on self-report personality tests is a widespread practice which degrades the construct validity of personality tests when they are used in personnel selection contexts and may lead to suboptimal hiring decisions (Donovan, Dwight, (&) Hurtz, 2003; Schmit (&) Ryan, 1993). While much is known about the factors which enable job applicants to successfully engage in faking (Tett, Freund, Christiansen, Fox, (&) Coaster, 2012), far less is known about how specific applicant perceptions...
Show moreFaking on self-report personality tests is a widespread practice which degrades the construct validity of personality tests when they are used in personnel selection contexts and may lead to suboptimal hiring decisions (Donovan, Dwight, (&) Hurtz, 2003; Schmit (&) Ryan, 1993). While much is known about the factors which enable job applicants to successfully engage in faking (Tett, Freund, Christiansen, Fox, (&) Coaster, 2012), far less is known about how specific applicant perceptions throughout the hiring process influence their decision to engage in this practice. To this end, this study applied Vroom's (1964) expectancy theory to the study of applicant faking. Following the work of prior researchers (Peterson, Griffith, (&) Converse, 2009), this study incorporated an experimental paradigm in which participants were led to believe that they were completing a personality test as part of the hiring process.Results of the study suggested that applicant faking on personality tests within personnel selection contexts is largely driven by valence (the extent to which applicants perceive the job to which they are applying as desirable) and expectancy judgments (an applicant's self-efficacy regarding their ability to successfully engage in faking). However, the three-way interaction between valence, instrumentality, and expectancy judgments which forms the crux of Vroom's (1964) theory did not demonstrate a significant impact on subsequent faking. A positive relationship between cognitive ability and faking was also found, suggesting that highly intelligent job applicants are more prone to engage in this behavior. In addition, applicant integrity demonstrated no relationship to faking behavior, suggesting that job applicants may not view the practice as being unethical. The potential implications of these findings in real-world selection contexts was discussed.
Show less - Date Issued
- 2017
- Identifier
- CFE0006627, ucf:51298
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006627
- Title
- Determinants of Terrorist Target Selection: A Quantitative Analysis.
- Creator
-
Haywood, Taylor, Handberg, Roger, Dolan, Thomas, Boutton, Andrew, Vasquez, Joseph, University of Central Florida
- Abstract / Description
-
Existing research on the subject of terrorism is vast, spanning causes of terrorism, the membership of terrorist groups, types of terrorist attacks, and more. One area of terrorism research, though, has received only limited consideration: terrorist target selection. What research does exist explains target selection almost exclusively as a function of ideology (Asal et al. 2009, 270 and 274; Drake 1998b, 54-56 and 58). However, such a limited causal focus obscures other possible, and...
Show moreExisting research on the subject of terrorism is vast, spanning causes of terrorism, the membership of terrorist groups, types of terrorist attacks, and more. One area of terrorism research, though, has received only limited consideration: terrorist target selection. What research does exist explains target selection almost exclusively as a function of ideology (Asal et al. 2009, 270 and 274; Drake 1998b, 54-56 and 58). However, such a limited causal focus obscures other possible, and probable, explanations of terrorist target selection. This paper proposes an alternative explanation of terrorist target selection that includes ideological and terrorist group capability variables, as well as a variable measuring the security levels in the geographic areas in which terrorist attacks take place. A research design employing multiple ordinary least squares regression is utilized. The findings demonstrate the importance of the independent variables, as well as the significance of the effects of the two-way and three-way interactions of variables from the three categories. Furthermore, the multiple regression models explain a greater percentage of the effects of the independent variables on the percentage of attacks against civilian targets when the three-way interaction variable is included than when this interaction variable is not included. From these findings, two primary policy implications are derived.
Show less - Date Issued
- 2017
- Identifier
- CFE0006744, ucf:51853
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006744
- Title
- Using Technology in the Treatment of Selective Mutism: The Incorporation of Mobile Applications.
- Creator
-
Bunnell, Brian, Beidel, Deborah, Rapport, Mark, Neer, Sandra, Hundley, Gulnora, University of Central Florida
- Abstract / Description
-
Selective mutism (SM) is a diagnosis marked by withdrawal of speech in certain social situations. The treatment of SM is often a difficult and lengthy process and there are many barriers to successful intervention. Behavioral therapy is most effective in the treatment of SM and the addition of therapeutic activities such as games and mobile devices may provide distinct advantages to this treatment (i.e., decreased patient anxiety levels and more active engagement). The current investigation...
Show moreSelective mutism (SM) is a diagnosis marked by withdrawal of speech in certain social situations. The treatment of SM is often a difficult and lengthy process and there are many barriers to successful intervention. Behavioral therapy is most effective in the treatment of SM and the addition of therapeutic activities such as games and mobile devices may provide distinct advantages to this treatment (i.e., decreased patient anxiety levels and more active engagement). The current investigation examined the utility of mobile applications during the behavioral treatment of SM as well as the effect of using mobile applications on child-reported and physiological indicators of anxious responding. Results indicated that children made remarkable treatment gains in just two treatment sessions (i.e., spoke to the clinician within 22 minutes of treatment and held five, five-minute conversations with additional adults during a second session) regardless of modality of delivery (using mobile applications, other activities, or reinforcement alone). Children shaped to speak with the inclusion of mobile applications reported less anxiety and exhibited decreased physiological anxious distress during treatment. The utility of mobile applications during the treatment of SM is discussed in addition to areas for future research (e.g., mobile-based treatment dissemination initiatives).
Show less - Date Issued
- 2015
- Identifier
- CFE0005767, ucf:50087
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005767
- Title
- IN VITRO SELECTION OF DNA APTAMERS AGAINST PROSTATE CANCER PEPTIDE BIOMARKERS.
- Creator
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Kuguoglu, Elif, Kolpashchikov, Dmitry, University of Central Florida
- Abstract / Description
-
This project is aimed toward finding DNA aptamers against prostate cancer peptide antigens. DNA aptamers can function to find and indicate the presence of certain molecules in a specimen. These aptamers will be obtained through the process of evolutionary selection, a specific process called SELEX which stands for Systemic Evolution of Ligands by Experimental Enrichment. By conducting several rounds of SELEX, a DNA aptamer will be selected to bind to a known peptide antigen. A biotinylated...
Show moreThis project is aimed toward finding DNA aptamers against prostate cancer peptide antigens. DNA aptamers can function to find and indicate the presence of certain molecules in a specimen. These aptamers will be obtained through the process of evolutionary selection, a specific process called SELEX which stands for Systemic Evolution of Ligands by Experimental Enrichment. By conducting several rounds of SELEX, a DNA aptamer will be selected to bind to a known peptide antigen. A biotinylated column will be utilized to stabilize a random library of DNA aptamers, and those peptides that bind to certain aptamers will cause a conformational change leading to the elution of those specific DNA aptamers. This SELEX process will be conducted again on the eluted aptamers to further select for strong binding DNA aptamers. The DNA aptamers that are obtained can further on be sequenced or used for prostate cancer research studies. Another possible usage of aptamers is to diagnose and determine the stage of various different cancer types. Our prediction is that this research will produce a DNA aptamer that will bind to a specific prostate cancer peptide antigen.
Show less - Date Issued
- 2014
- Identifier
- CFH0004671, ucf:45294
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004671
- Title
- EVENT PLANNERS' RATINGS OF DESTINATION SELECTION VARIABLES: A COMPARISON BETWEEN MEMBERS OF THREE PROFESSIONAL ASSOCIATION GROUPS.
- Creator
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Godlewska, Marta, Breiter, Deborah, University of Central Florida
- Abstract / Description
-
Several researchers have attempted to understand the destination selection criteria that are important to event planners (Crouch & Ritchie, 1998; Getz, 2003; Oppermann, 1996). However, an examination of the previous studies indicated that only limited understanding of the destination selection criteria has been provided. There is little research that compares event planners belonging to different professional associations and their rating of destination selection criteria. This study examined...
Show moreSeveral researchers have attempted to understand the destination selection criteria that are important to event planners (Crouch & Ritchie, 1998; Getz, 2003; Oppermann, 1996). However, an examination of the previous studies indicated that only limited understanding of the destination selection criteria has been provided. There is little research that compares event planners belonging to different professional associations and their rating of destination selection criteria. This study examined the differences that exist between three groups of event planners in rating thirteen destination selection variables. The study provides more understanding in the search of an optimal combination of destination selection mix based on multiple dependent variables. This study found significant differences in ratings of five out of thirteen destination selection variables by event planners who were the members of three different associations. Therefore it is providing a valuable contribution to the existing body of literature. From a practical standpoint, this study can help by providing information about how planners of different events feel about certain destination criteria at the time a destination selection is made. All parties with a vested interest in the event industry may use this information to appropriately position their services in the market and tailor their products to better compete for the limited number of events in an environment where the space to host such events continues to grow.
Show less - Date Issued
- 2006
- Identifier
- CFE0001469, ucf:47094
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001469
- Title
- JUVENILE GREEN TURTLE (CHELONIA MYDAS) FORAGING ECOLOGY:FEEDING SELECTIVITY AND FORAGE NUTRIENT ANALYSIS.
- Creator
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Gilbert, Eliza, Ehrhart, Llewellyn, University of Central Florida
- Abstract / Description
-
For the endangered green turtle, Chelonia mydas, a fundamental component of recovery and conservation is an understanding of its foraging ecology. Foraging optimality models suggest animals will select resources of high quality over those of low quality. For green turtles, this behavior is important, as sufficient quantities of nutritionally adequate forage items are necessary for growth and reproduction. One intrinsic element in the understanding of green turtle foraging ecology is to...
Show moreFor the endangered green turtle, Chelonia mydas, a fundamental component of recovery and conservation is an understanding of its foraging ecology. Foraging optimality models suggest animals will select resources of high quality over those of low quality. For green turtles, this behavior is important, as sufficient quantities of nutritionally adequate forage items are necessary for growth and reproduction. One intrinsic element in the understanding of green turtle foraging ecology is to identify and document the availability and quality of forage resources preferred by green turtles. The objectives of this study were: 1) determine whether juvenile green turtles showed a feeding preference by comparing prey items in the diet to the availability of those items in the habitat, 2) identify species for which there was selection or avoidance, 3) identify nutritional factors determining selection or avoidance of prey items, and 4) evaluate the nutritional content of the diet. This research was conducted by comparing lavage samples from juvenile green turtles to samples from benthic surveys within the habitat. To determine feeding preference, Ivlev's Electivity Index was used to compare ingested species of algae with those available in the habitat. Nutritional analysis of forage was conducted to identify possible nutrients relating to feeding preference. Juvenile green turtles selectively foraged on Chlorophyta and Rhodophyta. Results indicate that diet selection was based on nutritional content. Both the composite diet and the main diet item, Hypnea spp, had a higher gross energy value, were higher in protein, and lower in fiber than prey items that were avoided. Conservation of green turtles requires effective habitat management, which must be informed by an understanding and evaluation of the habitat. For juvenile green turtles, this study indicates that habitats dominated by Chlorophyta and Rhodophyta may be more important for the health of green turtle populations than habitats dominated by Phaeophyta.
Show less - Date Issued
- 2005
- Identifier
- CFE0000487, ucf:46355
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000487
- Title
- SMOOTHING PARAMETER SELECTION IN NONPARAMETRIC FUNCTIONAL ESTIMATION.
- Creator
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Amezziane, Mohamed, Ahmad, Ibrahim, University of Central Florida
- Abstract / Description
-
This study intends to build up new techniques for how to obtain completely data-driven choices of the smoothing parameter in functional estimation, within the confines of minimal assumptions. The focus of the study will be within the framework of the estimation of the distribution function, the density function and their multivariable extensions along with some of their functionals such as the location and the integrated squared derivatives.
- Date Issued
- 2004
- Identifier
- CFE0000307, ucf:46314
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000307
- Title
- SEX-BIASED PARASITISM AND THE REPRODUCTIVE COSTS OF PARASITES IN A SOCIAL AFRICAN GROUND SQUIRREL.
- Creator
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Hillegass, Melissa, Waterman, Jane, University of Central Florida
- Abstract / Description
-
Vertebrate males frequently carry higher numbers of parasites than females. This bias in parasite loads could be a consequence of sexual selection. Grouping species are also assumed to be afflicted with larger numbers of parasites than solitary animals and associated costs of this parasitism could vary with group size or structure. I examined sex-biased parasitism and the influence of group size on parasite loads in Cape ground squirrels (Xerus inauris), a highly social species that occurs in...
Show moreVertebrate males frequently carry higher numbers of parasites than females. This bias in parasite loads could be a consequence of sexual selection. Grouping species are also assumed to be afflicted with larger numbers of parasites than solitary animals and associated costs of this parasitism could vary with group size or structure. I examined sex-biased parasitism and the influence of group size on parasite loads in Cape ground squirrels (Xerus inauris), a highly social species that occurs in the arid regions of southern Africa. Males carried three times as many ectoparasites as females, but females harbored nearly three times more endoparasites than males. Amount of time spent (per hour) autogrooming was similar between males and females, but amount time spent allogrooming by adult female was over eleven times that of adult males. Longer allogrooming of group members could be decreasing the numbers of ectoparasites of group members and ultimately the group. Males infrequently give or receive allogrooming and travel in very large home ranges, potentially increasing their exposure to ectoparasites. However, movement throughout a large home range may result in males foraging in areas with lower densities of fecal pellets, which could explain the lower endoparasite loads observed in males. When I considered the age class of group members, female age classes were similarly parasitized but male age classes were not. Sub-adult males carried similar ectoparasite loads to adult males and similar endoparasite loads to adult females. This result is of particular interest because sub-adult males are becoming scrotal but typically remain in the group until adulthood. Sexual selection does appear to influence parasite loads in this species, and parasite removal or avoidance potentially mitigates individual parasite loads and their associated costs. Parasites can be detrimental to the health, longevity, and reproduction of their hosts, but these costs are rarely quantified. I removed ectoparasites and endoparasites from Cape ground squirrels for three months and evaluated changes in female body mass, reproduction, burrow use, and grooming in response to parasite removal. Female body mass did not increase with parasite removal, but reproductive success (per capita offspring raised to emergence) increased nearly four-fold, while allogrooming by treated females decreased. Since breeding is highest in the late winter dry season when fewer resources are available, the impact of parasites may be highest during this season. Lactation and gestation are the most physiological stressful processes that females undergo, and the dramatic increase in reproductive success in treated females suggests that these females are able to allocate more resources to reproduction than females afflicted with parasites. These results suggest that studies investigating reproduction and fecundity must consider the vulnerability of the host to parasite infection and the potential impact on reproductive success.
Show less - Date Issued
- 2007
- Identifier
- CFE0001958, ucf:47455
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001958
- Title
- REJECTION IN THE JOB SELECTION PROCESS: THE EFFECTS OF INFORMATION & SENSITIVITY.
- Creator
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Yonce, Clayton, Fritzsche, Barbara, University of Central Florida
- Abstract / Description
-
Most people will experience rejection in the job selection process. Rejection from job opportunities is often issued via a letter from a hiring manager. These letters elicit reactions from applicants who may, in turn, have less favorable self perceptions and less favorable perceptions of the organization from which the applicant was rejected. Numerous research articles have been published that deal with delivering notification of selection and/or rejection to applicants in the job selection...
Show moreMost people will experience rejection in the job selection process. Rejection from job opportunities is often issued via a letter from a hiring manager. These letters elicit reactions from applicants who may, in turn, have less favorable self perceptions and less favorable perceptions of the organization from which the applicant was rejected. Numerous research articles have been published that deal with delivering notification of selection and/or rejection to applicants in the job selection process. However, relatively few use a realistic laboratory design to obtain results. This study examined the effects of sensitivity and information in notifications of rejection when applicants are rejected in the job selection process. A more realistic laboratory design was used to increase the psychological fidelity of the job selection situation. One hundred forty undergraduate students participated in this study. Participants were told to imagine that they were graduate school applicants. Then, the participants completed a fake graduate school admissions test and received notification of rejection from a fake graduate school. Participants were assigned to conditions (letters varying in sensitivity and information type) randomly and the participants completed a post-notification of rejection survey that captured their self and organizational perceptions. Additionally, moderating variables were explored.
Show less - Date Issued
- 2005
- Identifier
- CFE0000877, ucf:46654
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000877
- Title
- THE RISKS AND BENEFITS OF SELECTIVE SEROTONIN REUPTAKE INHIBITORS AND THE EFFECT OF PARENT-CHILD COMPLIANCE ON MEDICATION TEACHING IN PEDIATRIC ANXIETY DISORDERS.
- Creator
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Nizam, Sabiha, Dever, Kimberly, University of Central Florida
- Abstract / Description
-
Pediatric anxiety disorders characterized as Generalized, Separation, and Social Anxiety Disorders, are chronic debilitating conditions that leave children feeling tense and isolated, both physically and emotionally. Selective serotonin reuptake inhibitors (SSRIs) are a classification of antidepressants that can be prescribed to children diagnosed with these disorders. SSRIs have been shown to be effective in treating anxiety disorders in children. The purpose of this literature review was to...
Show morePediatric anxiety disorders characterized as Generalized, Separation, and Social Anxiety Disorders, are chronic debilitating conditions that leave children feeling tense and isolated, both physically and emotionally. Selective serotonin reuptake inhibitors (SSRIs) are a classification of antidepressants that can be prescribed to children diagnosed with these disorders. SSRIs have been shown to be effective in treating anxiety disorders in children. The purpose of this literature review was to examine and determine if there are more risks or benefits associated with SSRIs, as well as evaluate teaching and education regarding anxiety disorder medication compliance in both children and parents. A secondary purpose of this research was to provide recommendations in nursing practice to allow children to feel more involved in their medical regimen. The following databases were used for the search: CINAHL, Academic Search Premier, and Web of Science. Key terms used in the search include but are not limited to: child* and anxiety, not autism, and selective serotonin reuptake inhibitors, OR SSRI*, OR adolsecen*, not med*, pediatric*, OR side effects. The results suggest that the benefits of SSRI therapy in children with anxiety disorder, when taken on a regularly scheduled basis, outweigh the risks, however more research aimed at compliance with SSRI therapy in children and parents is necessary. Further research analyzing children with anxiety disorders is needed to assess SSRI usage based specifically on their developmental age, and the inclusion of appropriate teaching and explanation related to their diagnoses to identifying stressors that can include behavioral therapy as well.
Show less - Date Issued
- 2016
- Identifier
- CFH2000020, ucf:45574
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000020
- Title
- INITIAL VALIDATION OF NOVEL PERFORMANCE-BASED MEASURES: MENTAL ROTATION AND PSYCHOMOTOR ABILITY.
- Creator
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Fatolitis, Philip, Jentsch, Florian, University of Central Florida
- Abstract / Description
-
Given the high-risk nature of military flight operations and the significant resources required to train U.S. Naval Aviation personnel, continual improvement is required in the selection process. In addition to general commissioning requirements and aeromedical standards, the U.S. Navy utilizes the Aviation Selection Test Battery (ASTB) to select commissioned aviation students. Although the ASTB has been a good predictor of aviation student performance in training, it was proposed that...
Show moreGiven the high-risk nature of military flight operations and the significant resources required to train U.S. Naval Aviation personnel, continual improvement is required in the selection process. In addition to general commissioning requirements and aeromedical standards, the U.S. Navy utilizes the Aviation Selection Test Battery (ASTB) to select commissioned aviation students. Although the ASTB has been a good predictor of aviation student performance in training, it was proposed that incremental improvement could be gained with the introduction of novel, computer administered performance-based measures: Block Rotation (BRT) and a Navy-developed Compensatory Tracking task. This work constituted an initial validation of the BRT, an interactive virtual analog of Shepard-Metzler's (1971) Mental Rotation task that was developed with the intention of quantifying mental rotation and psychomotor ability. For Compensatory Tracking, this work sought to determine if data gathered concord with results in extant literature, confirming the validity of the task. Data from the BRT were examined to determine task reliability and to formulate relevant quantitative/predictive performance human models. Results showed that the BRT performance is a valid spatial ability predictor whose output can be modeled, and that Compensatory Tracking task data concord with the psychometric properties of tracking tasks that have been previously presented in the literature.
Show less - Date Issued
- 2008
- Identifier
- CFE0002413, ucf:47764
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002413
- Title
- Business in the Estuary, Party in the Sea: Migration Patterns of Striped Mullet (Mugil cephalus) Within the Indian River Lagoon Complex.
- Creator
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Myers, Olivia, Cook, Geoffrey, Mansfield, Kate, Reyier, Eric, University of Central Florida
- Abstract / Description
-
Commercial and recreational environmental enterprises in the Indian River Lagoon (IRL), Florida supply nearly 10,000 jobs and produce $1.6 billion dollars a year in revenue. These waters contain iconic species of sportfish, including red drum, snook, and sea trout, as well as their lower trophic level prey such as snapper and mullet. Striped mullet (Mugil cephalus) are both commercially valuable as well as an indicator species for overall ecosystem health. From September to December, mullet...
Show moreCommercial and recreational environmental enterprises in the Indian River Lagoon (IRL), Florida supply nearly 10,000 jobs and produce $1.6 billion dollars a year in revenue. These waters contain iconic species of sportfish, including red drum, snook, and sea trout, as well as their lower trophic level prey such as snapper and mullet. Striped mullet (Mugil cephalus) are both commercially valuable as well as an indicator species for overall ecosystem health. From September to December, mullet in the IRL undergo an annual migration from their inshore foraging habitats to oceanic spawning sites. However, their actual migratory pathways remain unknown. To address this knowledge gap, I utilized passive acoustic telemetry to assess the migration patterns of M. cephalus within the IRL complex, particularly focusing on movement pathways from inshore aggregation sites to oceanic inlets to spawn. Coupling environmental metrics with movement data, I evaluated catalysts for migration as well as travel routes through the estuary. Network analyses identified potential conservation areas of interest and sites needing management intervention. Impoundments around the Merritt Island National Wildlife Refuge appear to serve as an important refuge area for striped mullet while the Banana and Indian Rivers act as corridors during their inshore migratory movements. The environmental metrics of depth, temperature, dissolved oxygen, pH, barometric pressure, and photoperiod were the best predictors for the number of detections and residency time produced by two case studies of striped mullet activity. An emphasis on spatial fisheries management along with vigilant environmental monitoring will ensure the status of this species, to the benefit of both natural and human systems in the Indian River Lagoon. The knowledge generated as a result of this project may also provide a framework for sustainably managing other migratory baitfish.
Show less - Date Issued
- 2019
- Identifier
- CFE0007895, ucf:52768
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007895
- Title
- Non-Hermitian Optics.
- Creator
-
Ulhassan, Absar, Christodoulides, Demetrios, Khajavikhan, Mercedeh, Likamwa, Patrick, Kaup, David, University of Central Florida
- Abstract / Description
-
From the viewpoint of quantum mechanics, a system must always be Hermitian since all its corresponding eigenvalues must be real. In contrast, the eigenvalues of open systems-unrestrained because of either decay or amplification-can be in general complex. Not so long ago, a certain class of non-Hermitian Hamiltonians was discovered that could have a completely real eigenvalue spectrum. This special class of Hamiltonians was found to respect the property of commutation with the parity-time (PT)...
Show moreFrom the viewpoint of quantum mechanics, a system must always be Hermitian since all its corresponding eigenvalues must be real. In contrast, the eigenvalues of open systems-unrestrained because of either decay or amplification-can be in general complex. Not so long ago, a certain class of non-Hermitian Hamiltonians was discovered that could have a completely real eigenvalue spectrum. This special class of Hamiltonians was found to respect the property of commutation with the parity-time (PT) operator. Translated into optics, this implies a balance between regions exhibiting gain and loss. Traditionally, loss has been perceived as a foe in optics and something that needs to be avoided at all costs. As we will show, when used in conjunction with gain, the presence of loss can lead to a host of counterintuitive outcomes in such non-Hermitian configurations that would have been otherwise unattainable in standard arrangements. We will study PT symmetric phase transitions in various optical settings that include semiconductor microrings and coupled fiber cavities, and show how they can allow mode-selectivity in lasers. One of the key outcomes of this effort was the realization of higher order degeneracies in a three-cavity laser configuration that can exhibit orders-of-magnitude larger sensitivity to external perturbations. We will also consider systems that display nonlinear effects such as gain saturation, thus allowing novel phase transitions. Some interesting properties associated with degeneracies in non-Hermitian settings will be investigated as well. Such degeneracies, called exceptional points (EPs), are much more drastic compared to standard degeneracies of eigenvalues because the corresponding eigenvectors also coalesce, which in turn reduces the dimensionality of the phase space. We will show that dynamic parameter contours enclosing or close to EPs can lead to a robust chiral mode conversion process (-) something that can be potentially used to realize omni-polarizing optical devices.
Show less - Date Issued
- 2018
- Identifier
- CFE0007259, ucf:52182
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007259
- Title
- Development and Characterization of Solid-Contact Paper-Based and Micro Ion-Selective Electrodes for Environmental Analysis.
- Creator
-
Armas, Stephanie, Chumbimuni Torres, Karin, Beazley, Melanie, Santra, Swadeshmukul, University of Central Florida
- Abstract / Description
-
Ion-selective electrodes (ISEs) have extensively been used for food analysis, as medical diagnostic tools, and for some environmental applications. However, ISEs are hindered by the need of a bulky reference electrode and the pre-conditioning step of the sensor, which can often be lengthy. This work will discuss how the direct addition of target analyte into the cocktail sensing membrane can circumvent the pre-conditioning step. Furthermore, the work is presented in an optimized ready-to-use...
Show moreIon-selective electrodes (ISEs) have extensively been used for food analysis, as medical diagnostic tools, and for some environmental applications. However, ISEs are hindered by the need of a bulky reference electrode and the pre-conditioning step of the sensor, which can often be lengthy. This work will discuss how the direct addition of target analyte into the cocktail sensing membrane can circumvent the pre-conditioning step. Furthermore, the work is presented in an optimized ready-to-use single strip design, where the bulky glass reference electrode (RE) is no longer needed. The bulky RE was replaced by drop casting a simple two-component mixture consisting of the co-polymer methyl methacrylate-co-decyl methacrylate and the ionic liquid 1-Ethyl-3-methylimidazolium bis (trifluoromethane sulfonyl) amide. Furthermore, this work will also highlight the benefits of solid-contact ISEs, specifically focusing on two solid- contact platforms: 1) paper-based and 2) a micro-electrode platform. Paper-based based sensors were designed to be used as a possible diagnostic tool to be implemented in undeveloped countries to monitor low levels of potassium and iodide, as model ions. The micro((&)#181;) ISEs were applied for the in-situ analysis of zinc in citrus plants as a mean to monitor and assess disease progression or therapy.
Show less - Date Issued
- 2018
- Identifier
- CFE0007152, ucf:52316
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007152
- Title
- THEORETICAL STUDY OF BEAM TRANSFORMATIONS BY VOLUME DIFFRACTION.
- Creator
-
Mokhov, Sergiy, Zeldovich, Boris, University of Central Florida
- Abstract / Description
-
Laser beams can be manipulated by volume diffractive elements in addition to conventional optical elements like mirrors, lenses, and beam splitters. Conventional optical elements can be described by applying the basic laws of reflection and refraction at the surfaces of the elements. Even diffraction by surface gratings utilizes relatively simple mathematics. This is to be contrasted with the volume diffraction, which requires coupled wave theory in the slowly varying envelope approximation ...
Show moreLaser beams can be manipulated by volume diffractive elements in addition to conventional optical elements like mirrors, lenses, and beam splitters. Conventional optical elements can be described by applying the basic laws of reflection and refraction at the surfaces of the elements. Even diffraction by surface gratings utilizes relatively simple mathematics. This is to be contrasted with the volume diffraction, which requires coupled wave theory in the slowly varying envelope approximation (SVEA) to obtain accurate results. Efficient spatially distributed diffraction of laser beams is possible due to the high coherence of laser light, and it occurs at specific resonant Bragg conditions. This research work is inspired and driven by the successful development of recording technology for robust, high-efficiency volume Bragg gratings (VBGs) in photo-thermo-refractive (PTR) glass. Mostly VBGs of the reflective type are discussed in this dissertation. Starting with an analysis of electro-magnetic wave propagation in layered media, we have reformulated Fresnel and volume reflection phenomena in terms of a convenient parameter S - strength of reflection. The influence that the different non-uniformities inside a VBG have on its spectral properties has been examined. One important result of this work is the proposal of moire VBG and the derivation of an analytical expression for its bandwidth. A multiplexed VBG used as a coherent combiner is discussed as well. Beam distortion via transmission through and/or reflection by a heated VBG due to residual absorption is analyzed.
Show less - Date Issued
- 2011
- Identifier
- CFE0004054, ucf:49152
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004054
- Title
- Is Selective Mutism an Emotion Regulation Strategy for Children with Social Phobia? A Single Case Design Investigation.
- Creator
-
Scott, Samantha, Beidel, Deborah, Rapport, Mark, Cassisi, Jeffrey, Hundley, Gulnora, University of Central Florida
- Abstract / Description
-
To determine whether children with selective mutism (SM) withhold speech to regulate their emotional arousal and decrease automatic distress, the current study examines the behavioral and physiological responses of children with SM in comparison to children with social phobia (SP) and children with no psychiatric disorder (TD) as they participate in two social situations. A single case design strategy is used to compare behavioral and physiological responses both within and across groups....
Show moreTo determine whether children with selective mutism (SM) withhold speech to regulate their emotional arousal and decrease automatic distress, the current study examines the behavioral and physiological responses of children with SM in comparison to children with social phobia (SP) and children with no psychiatric disorder (TD) as they participate in two social situations. A single case design strategy is used to compare behavioral and physiological responses both within and across groups. Examining the temporal sequencing of behaviors and physiology provides a direct test of the utility of emotion regulation theory as it pertains to children with social phobia/selective mutism. The results indicate that children with SM show elevated arousal and emotional reactivity across all interaction segments relative to other children. Unique affective, behavioral and physiological responses occur between and within groups in relation to situational demands. The temporal sequencing of behavioral and physiological responses suggests that behavioral deficits may be related to underutilized and/or deficient physiological response systems and that not speaking represents a primitive avoidance strategy by children with SM to regulate extreme physiological arousal.
Show less - Date Issued
- 2012
- Identifier
- CFE0004438, ucf:49348
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004438
- Title
- IMPROVING THE ADVERSE IMPACT AND VALIDITY TRADE-OFF IN PARAETO OPTIMAL COMPOSITES: A COMPARISON OF WEIGHTS DEVELOPED ON CONTEXTUAL VS TASK PERFORMANCE.
- Creator
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Tsang, Howin, Wooten, William, University of Central Florida
- Abstract / Description
-
Recent research in reducing adverse impact in personnel selection has focused on the use of various weighting schemes to balance levels of adverse impact and the validity of selection processes. De Corte Lievens & Sackett (2007) suggested the use of the normal boundary intersection method to create a number of weights that optimize adverse impact and criterion validity. This study seeks to improve the efficacy of this solution by looking at specific types of performance, namely task and...
Show moreRecent research in reducing adverse impact in personnel selection has focused on the use of various weighting schemes to balance levels of adverse impact and the validity of selection processes. De Corte Lievens & Sackett (2007) suggested the use of the normal boundary intersection method to create a number of weights that optimize adverse impact and criterion validity. This study seeks to improve the efficacy of this solution by looking at specific types of performance, namely task and contextual performance. It will investigate whether a focus on contextual performance will improve the trade-off by requiring smaller losses in validity for greater gains in adverse impact. This study utilized data from 272 applicants for exempt positions at a multinational financial institution. The two sets of Paraeto optimal composite were developed, one based on contextual performance and the other based on task performance. Results were analyzed based on levels of adverse impact and validity of weights generated using each method. Results indicate that reducing adverse impact required a greater validity trade-off for task performance than contextual performance. Application of this method would allow for greater reductions to adverse impact than the original method while retaining a validity coefficient of 95% of the maximum achieved with regression weighting. Though this method would limit practitioners to selecting based on contextual performance, the use of minimal cut-off scores on task predictors or job experience could allow employers to incorporate task measures while further reducing adverse impact.
Show less - Date Issued
- 2010
- Identifier
- CFE0003399, ucf:48386
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003399
- Title
- THE INFLUENCE OF SEXUAL SELECTION ON BEHAVIORAL AND PHYSIOLOGICAL MECHANISMS UNDERLYING REPRODUCTIVE SUCCESS IN MALE CAPE GROUND SQUIRRELS (XERUS INAURIS).
- Creator
-
Manjerovic, Mary, Waterman, Jane, University of Central Florida
- Abstract / Description
-
Sexual selection is considered a powerful evolutionary force responsible for the enormous diversity found in reproductive morphology, physiology, and behavior. I addressed questions related to selection in the Cape ground squirrel (Xerus inauris), a species characterized as highly social and promiscuous. These attributes often are responsible for variance in male reproductive success and as such, sexual selection theory predicts increased opportunity for sexual selection. I confirm that the...
Show moreSexual selection is considered a powerful evolutionary force responsible for the enormous diversity found in reproductive morphology, physiology, and behavior. I addressed questions related to selection in the Cape ground squirrel (Xerus inauris), a species characterized as highly social and promiscuous. These attributes often are responsible for variance in male reproductive success and as such, sexual selection theory predicts increased opportunity for sexual selection. I confirm that the predominant mechanism underlying genital evolution and competition for paternity in X. inauris is sperm competition. I find evidence that investment in sperm competition is costly and may reflect immunocompetence. I quantify reproductive success as it relates to alternative male tactics and female resource distribution. I find that male X. inauris alternative reproductive tactics differ within and across populations most likely due to differences in female resource distribution. In areas where females are evenly distributed, dispersed males encounter more estrous females, and therefore have increased breeding opportunities. However, the decision to remain natal does not preclude reproduction. I determine that these tactics are most likely conditional with equal fitness payoffs. Males, regardless of tactic, invest more in post-copulatory competition (e.g. sperm competition, copulatory plugs) than males within a population with a clustered distribution of breeding females. In the latter area, males form dominance hierarchies that affect copulatory success and lead to greater skews in reproduction among males. Both sites have evidence of a highly skewed variance in reproduction and intense sexual selective pressure. My results suggest these populations have increased opportunities for selection but that different mechanisms of intrasexual competition may result in rapid evolutionary change within this species.
Show less - Date Issued
- 2010
- Identifier
- CFE0003400, ucf:48402
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003400
- Title
- HABITAT USE BY THE SOUTHEASTERN BEACH MOUSE (PEROMYSCUS POLIONOTUS NIVEIVENTRIS) AT CAPE CANAVERAL AIR FORCE STATION, FLORIDA.
- Creator
-
Simmons, Kathryn, Stout, I. Jack, University of Central Florida
- Abstract / Description
-
Successful recovery of the federally threatened southeastern beach mouse (Peromyscus polionotus niveiventris) depends in part on an understanding of their habitat requirements. I studied habitat use by beach mice at Cape Canaveral Air Force Station, Florida from March 2005 until March 2006. I livetrapped six grids, three on coastal dunes and three within scrub located inland from the coast. On each grid and trap station, I quantified the extent of bare ground, woody vegetation, non-woody...
Show moreSuccessful recovery of the federally threatened southeastern beach mouse (Peromyscus polionotus niveiventris) depends in part on an understanding of their habitat requirements. I studied habitat use by beach mice at Cape Canaveral Air Force Station, Florida from March 2005 until March 2006. I livetrapped six grids, three on coastal dunes and three within scrub located inland from the coast. On each grid and trap station, I quantified the extent of bare ground, woody vegetation, non-woody vegetation, height of vegetation, and percentage of coarse sand in the surface soil. I assessed trap success relative to these habitat variables using linear and multiple regression, correlation, and ordination. Significantly higher numbers of mice were captured in the scrub habitat relative to the coastal habitat. Linear regression of trap success against the habitat variables did not reveal any significant relationships at the level of grids. A non-metric multidimensional scaling model was designed to capture the vegetation heterogeneity at the trapping sites and clarify the results. This methodology identified a predominantly dune and predominately scrub cluster of trap sites. A bubble plot showed higher densities of beach mice using the scrub habitat types. These results suggest beach mice are selecting for those habitat variables defined by the ordination: higher vegetation height, more woody vegetation types, less bare ground, and less heterogeneity.
Show less - Date Issued
- 2009
- Identifier
- CFE0002605, ucf:48271
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002605
- Title
- Characterization of SLM-Manufactured Turbine Blade Microfeatures from Superalloy Powders.
- Creator
-
Ealy, Brandon, Kapat, Jayanta, Ahmed, Kareem, Vasu Sumathi, Subith, University of Central Florida
- Abstract / Description
-
The limits of gas turbine technology are heavily influenced by materials and manufacturing capabilities. Inconel remains the material of choice for most hot gas path (HGP) components in gas turbines, however recent increases in turbine inlet temperature (TIT) are associated with the development of advanced convective cooling methods and ceramic thermal barrier coatings. Increasing cycle efficiency and cycle specific work are the primary drivers for increasing TIT. Lately, incremental...
Show moreThe limits of gas turbine technology are heavily influenced by materials and manufacturing capabilities. Inconel remains the material of choice for most hot gas path (HGP) components in gas turbines, however recent increases in turbine inlet temperature (TIT) are associated with the development of advanced convective cooling methods and ceramic thermal barrier coatings. Increasing cycle efficiency and cycle specific work are the primary drivers for increasing TIT. Lately, incremental performance gains responsible for increasing the allowable TIT have been made mainly through innovations in cooling technology, specifically convective cooling schemes. An emerging manufacturing technology may further facilitate the increase of allowable maximum TIT, thereby impacting cycle efficiencies. Laser Additive Manufacturing (LAM) is a promising manufacturing technology that uses lasers to selectively melt powders of metal in a layer-by-layer process to directly manufacture components, paving the way to produce designs that are not possible with conventional casting methods. This study investigates manufacturing qualities seen in LAM methods and its ability to successfully produce complex microfeatures in a mock turbine blade leading edge. Various cooling features are incorporated in design, consisting of internal impingement cooling, internal lattice structures, and external showerhead cooling. The internal structure is designed as a lattice of intersecting cylinders in order to mimic that of a porous material. Through a non-destructive approach, the presented design is analyzed against the departure of the design by utilizing X-ray computed tomography (CT). Employing this non-destructive testing (NDT) method, a more thorough analysis of the quality of manufacture is established by revealing the internal structures of the porous region and internal impingement array. Variance distribution between the design and manufactured test article are carried out for both internal impingement and external transpiration hole diameters from CT data. Flow testing is performed to characterize the uniformity of porous regions and flow behavior across the entire article for various pressure ratios. Discharge coefficients of internal impingement arrays and porous structures are quantified. A numerical model of fluid flow through the exact CAD geometry is analyzed over the range of experimental flowrates. By comparison of experimental and numerical data, performance discrepancies associated with manufacturing quality are observed. Simplifying assumptions to the domain are evaluated to compare predictions of CFD using the exact geometry. This study yields quantitative data on the build quality of the LAM process, providing more insight as to whether it is a viable option for manufacture of micro-features in current turbine blade production.
Show less - Date Issued
- 2016
- Identifier
- CFE0006452, ucf:51428
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006452
