Spectroscopic investigation of the Cr to Tm energy transfer in Yttrium Aluminum Garnet (YAG) crystals

New and interesting schemes have recently been considered for the efficient operation of solid-state ionic laser systems. Often the available data on these systems were obtained only because they seemed directly related to the laser performance and provide no insight into the physical processes. A more systematic approach is desirable, where more attention is devoted to the elementary basic processes and to the nature of the mechanisms at work. It is with this aim that we have undertaken the present study. Yttrium Aluminum Garnet (Y4Al5O12), called YAG, has two desirable properties as host for rare earth impurities: (1) trivalent rare earth ions can replace the yttrium without any charge compensation problem, and (2) YAG crystals have high cutoff energies. The results of measurements and calculations indicate that the Cr(3+) ion in YAG can be used to sensitize efficiently the Tm(3+) ion

Animal Activities! : A Children\u27s Book for Vocabulary Intervention

This Honors Project was created as a culmination of research conducted in the fields of Speech-Language Pathology and English. It is a written and illustrated children’s book intended to be used during shared book reading between an adult and a child of preschool age who presents with a language delay or language disorder. Cloze structures are used throughout the book to elicit strategically selected vocabulary words from the child and aid in their vocabulary development. Elements and techniques used in children’s literature were also implemented throughout this book. This book is overall designed a therapy tool that can be used for the purpose of vocabulary intervention

Minor League baseball in the Sunbelt : the historical geography of the Southern League of Professional Baseball Clubs

The Southern League of Professional Baseball Clubs has been in existence since 1964. Although a history of the league has been recently completed, there has yet to be a study about the changes in the league\u27s geographical structure. Over the last thirty years, twenty-one different cities have been home to Southern League ballclubs. This thesis proposes to examine the historical geography of the league from its promotion to Double-A status in 1964 through the 1999 season while examining the relationship between the location of the ballparks, both past and present. The study will focus on the historical trends of franchise shifts to larger cities within the South and will focus on shifting of the ballpark locations to suburban sites or sites with excellent freeway access. Since its inception in 1964, this latest incarnation of the Southern League has migrated from small Southern cities to some of the largest metropoli the South has to offer. In addition, the sites of Southern League ballparks have gradually shifted from locations near their downtowns to suburban sites with easier automobile access. This move to the suburbs is not a strike against the great history of baseball, but a response to the changing geography of the Southern city, both in population distribution and economic dominance. The move to the suburbs mirrors the movement of retail, corporate and other entertainment establishments that have been part of the suburban landscape for decades

An Instrument to Assess Self-Statements During Public Speaking: Scale Development and Preliminary Psychometric Properties

Public speaking is the most commonly reported fearful social situation. Although a number of contemporary theories emphasize the importance of cognitive processes in social anxiety, there is no instrument available to assess fearful thoughts experienced during public speaking. The Self-Statements During Public Speaking (SSPS) scale is a 10-item questionnaire consisting of two 5-item subscales, the Positive Self-Statements (SSPS-P) and the Negative Self-Statements subscale (SSPS-N). Four studies report on the development and the preliminary psychometric properties of this instrument

Development and Validation of the Frost Multidimensional Perfectionism Scale–Brief

Twenty-five years ago, one of the first empirically validated measures of perfectionism, the Frost et al. Multidimensional Perfectionism Scale (F-MPS) was published. Since that time, psychometric studies of the original F-MPS have provided a plethora of evidence to support the potential development of a shorter yet still psychometrically robust version of the measure. Using confirmatory factor analyses across community and clinical samples, the current study identifies an eight-item F-MPS-Brief with two dimensions (i.e., striving and evaluative concerns) that evidences good internal consistency, measurement equivalence across ethnicities, and concurrent and convergent validity. This new, short version of the F-MPS captures well the bidimensional model of perfectionism that has emerged across studies over the past two decades and is suggested for use when a short yet high-performing assessment tool for this model is desired

“CAN’T LET IT GO”: THE PERSISTENCE OF CUE-DRIVEN REWARD-SEEKING DESPITE GOAL-RELATED CONSEQUENCES.

Humans possess an amazing repertoire of higher-order capacities for planning and pursing goals. However, everyday life requires continuous juggling of multiple priorities across various time scales. Given limited cognitive resources to attend to multiple priorities, over-attending to a given priority often comes at the expense of under-attending to other priorities. Compulsive over-prioritization of a specific stimulus or state is one of the hallmark signs of addiction. Once an individual progresses in the trajectory of addiction, substances and the cues that predict substance availability maintain a powerful hold over attention and behavior even after extended periods of abstinence; it appears they “can’t let it go.” Numerous measurement tools have been employed in cognitive psychology and neuroscience research to assess correlates and causal factors linked to addictive tendencies. This dissertation examines the reliability and validity of selective attention paradigms that have been adapted to study biased attentional priorities in humans, investigates the translational relevance of paradigms designed to measure incentive salience attribution in animals, and describes a novel method for measuring biased priorities in the management of multiple goals in dynamic environments. First the reliability and validity of the value-driven attentional capture (VDAC) paradigm was assessed. Across several experiments, poor reliability and multiple indices of poor validity were observed, suggesting this measure is not suitable for estimating individual differences or testing the effectiveness of intervention techniques. Next, the translational relevance of a Pavlovian conditioning task commonly used to train animals to associate rewards with cues and measure incentive salience attribution was assessed using an adapted eye-tracking paradigm. The majority of participants dwelled on and vigorously interacted with reward-predictive cues, indicating cues acquired incentive salience. The degree to which they interacted with the reward-predictive cues was related to the magnitude of attentional capture by these cues in a subsequent selective attention task. Finally, a novel paradigm for assessing behavioral tendencies to pursue reward opportunities, despite the accumulation of negative consequences, was tested. In general, participants persistently attempted to pursue rewards, even when reward-seeking behaviors had negative consequences for progress toward the overarching goals of the task. However this behavior was modulated by negative consequence-related feedback. The work presented in this dissertation has implications for the development of prevention, intervention and treatment techniques that could be individualized to address a multitude of addictive behaviors. Individuals with a history of addiction commonly report desire to change behaviors that have become maladaptive, but frequently relapse into past behavioral patterns. Prevention tools that utilize dynamic outcome feedback may help individuals recognize the slow build of consequences that occur when substance abuse conflicts with goals, before later stages of addiction have taken hold

Excited state dynamics of thulium ions in yttrium aluminum garnets

The processes that take place in the excited states of a trivalent Thulium (Tm) ion in an Yttrium Aluminum Garnet (YAG) crystal, being relevant to the use of this system for laser applications, have been the object of several studies. We have reexamined this system focusing our attention on the dynamics of Tm following its excitation in the H-3(sub 4) level. Under these conditions the system relaxes through a cross-relaxation process. H-3(sub 4) yields F-3(sub 4), H-3(sub 6) yields F-3(sub 4), whose rate depends upon both the concentration of the Tm ion and the temperature of the crystal. The excitation spectrum obtained by monitoring the 1.8 micron emission of Tm (due to the F-3(sub 4) yields H-3(sub 6) transition) indicates an increase in the contribution to this emission from the H-3(sub 4) level relative to the H-3(sub 5) level as the Tm concentration increases; this shows the increased role played by the H-3(sub 4) level in pumping the infrared emission. Correspondingly, the duration of the luminescence originating in the H-3(sub 4) level is shortened as the concentration of Tm increases. The concentration quenching of this lifetime can be fit to a model which assumes that the cross-relaxation is due to a dipole-dipole interaction; from this fit, the intrinsic Tm lifetime in the absence of cross relaxation can be derived. We have used this lifetime to calculate the rate of the cross-relaxation process. We have evaluated this rate as a function of the temperature and found it to be fastest at 77 K. We have also calculated the microscopic interaction parameters for the cross-relaxation process by using two independent experimental features: (1) the time evolution of the emission from the H-3(sub 4) level; and (2) the spectral overlap between the H-3(sub 4) yields F-3(sub 4) emission and the H-3(sub 6) yields F-3(sub 4) absorption. We have also considered the migration of excitation among the Tm ions in the F-3(sub 4) level and calculated the relevant microparameter by the use of the relevant spectral overlap. The data are consistent with the model in which the Tm ions, once excited into the H-3(sub 4) level decay by cross-relaxation to the F-3(sub 4), and then transfer rapidly their energy to other Tm ions

Effects of Anxiety on Attentional Allocation and Task Performance: An Information Processing Analysis

An information processing signal detection methodology was employed to examine attentional allocation and its correlates in both normal comparison (NC) and generalized anxiety disorder (GAD) participants. In particular, the impact of neutral distractor and negative feedback cues on performance of an attention vigilance task was investigated. Individuals with GAD (N = 15) evidenced impaired performance on an attention vigilance task relative to NC participants (N = 15) when neutral distractor cues were presented. Contrary to prediction, no group differences in performance were detected under conditions in which participants were presented negative feedback cues they were told were relevant to their performance. Instead, GAD participants exhibited improvement during the experimental task such that their performance was equivalent to NC participants. Across trials, the clinically anxious group endorsed significantly higher levels of worry and negative affectivity; however, they failed to respond with concomitant physical arousal (e.g. increased muscle tension). These data are discussed within the context of Eysenck and Calvo\u27s processing efficiency theory. Additionally, the results of this investigation provide support for Barlow\u27s conceptualization of anxiety as requiring the interaction of cognitive schema and physiological arousal

Developmental Changes in Analytic and Holistic Processes in Face Perception

Although infants demonstrate sensitivity to some kinds of perceptual information in faces, many face capacities continue to develop throughout childhood. One debate is the degree to which children perceive faces analytically versus holistically and how these processes undergo developmental change. In the present study, school-aged children and adults performed a perceptual matching task with upright and inverted face and house pairs that varied in similarity of featural or 2nd order configural information. Holistic processing was operationalized as the degree of serial processing when discriminating faces and houses [i.e., increased reaction time (RT), as more features or spacing relations were shared between stimuli]. Analytical processing was operationalized as the degree of parallel processing (or no change in RT as a function of greater similarity of features or spatial relations). Adults showed the most evidence for holistic processing (most strongly for 2nd order faces) and holistic processing was weaker for inverted faces and houses. Younger children (6-8 years), in contrast, showed analytical processing across all experimental manipulations. Older children (9-11 years) showed an intermediate pattern with a trend toward holistic processing of 2nd order faces like adults, but parallel processing in other experimental conditions like younger children. These findings indicate that holistic face representations emerge around 10 years of age. In adults both 2nd order and featural information are incorporated into holistic representations, whereas older children only incorporate 2nd order information. Holistic processing was not evident in younger children. Hence, the development of holistic face representations relies on 2nd order processing initially then incorporates featural information by adulthood