Solid State Nuclear Magnetic Resonance Investigations of Advanced Energy Materials
Year of Dissertation:
2009
In order to better understand the physical electrochemical changes that take place in lithium ion batteries and asymmetric hybrid supercapacitors solid state nuclear magnetic resonance (NMR) spectroscopy has been useful to probe and identify changes on the atomic and molecular level. NMR is used to characterize the local environment and investigate the dynamical properties of materials used in electrochemical storage devices (ESD). NMR investigations was used to better understand the chemical composition of the solid electrolyte interphase which form on the negative and positive electrodes of lithium batteries as well as identify the breakdown products that occur in the operation of the asymmetric hybrid supercapacitors. The use of nano-structured particles in the development of new materials causes changes in the electrical, structural and other material properties. NMR was used to investigate the affects of fluorinated and non fluorinated single wall nanotubes (SWNT). In this thesis three experiments were performed using solid state NMR samples to better characterize them.
Europium Complexes as Probes for Biological and Materials applications
Author:
Laurence Bensaid-Geyer
Year of Dissertation:
2009
Europium is a widely used lanthanide due to its emission in the visible region and its long life time. It is often complexed with ligands in order to serve different purposes in various domains: these complexes can be used as photostable biological probes but also as photoelectronic devices. This thesis interest will lie on both aspects. In chapter 2, we focused on europium phosphonates for targeting bone cancer. As we look at the adsorption of europium phosphonate to bone, possible scenario can take place: the complex can adsorb to the bone and/or the europium can transchelate from the ligand. If the europium transchelate, we looked at the possibility of a europium incorporation into the hydroxyapatite (HA) structure. We prove the presence of europium within the HA structure using various analytical and spectroscopic methods such as elemental analysis, X&ndashray diffraction (XRD), Infra-red (IR), luminescence studies, X&ndashray absorption fine structure (XAFS), and other spectroscopic analysis (SEM, BSE and EDS). In another part, the actual adsorption of europium phosphonate onto HA surface was studied. The adsorption was demonstrated based on luminescence studies showing a change of europium environment. In chapter 3, solution behavior of lanthanide complexes of the &alpha2&ndashP2W17O6110- ligand was reported to identify trends that will facilitate rational synthesis of hybrid organic lanthanide polyoxometalate complexes. Based on 31P NMR studies, the equilibrium between the 1:1 and the 1:2 species, that was observed by Pope for the Ce(III) analog is prevalent for the early-mid lanthanides. This equilibrium is slightly dependent on pH but seems to be very much influenced by larger poorly hydrated cations which appear to favor the 1:2 species for the early to mid lanthanides while they do not appear to influence the equilibrium for the later lanthanides. For all counterions, we found the 1:1 species stable with no trace of the 1:2 species. Finally, in chapter 4, we investigated Eu&alpha1&ndashP2W17O617- (EuPOM) for a layer by layer deposition application with Zn(phen)32+ (Zn(phen)) and its potential as a electroluminescence device. The depositions were monitored by UV-vis. We successfully fabricated multilayer film via electrostatic interaction between the polyanion EuPOM7- and the polycation Zn(phen)32+ until reaching four bilayers when the layers appeared to strip off. Also luminescence studies showed that the multilayer film demonstrated an effective luminescence activity due to the energy transfer through space from the phenanthroline to the europium ion.
The Effects Of Certain And Uncertain Reinforcement Procedures On The Quiz Submission And Performance Of College Students
Year of Dissertation:
2011
College instructors often provide homework so that their students can review class material; however some students do not take advantage of these review opportunities. This study compared the effects of a certain reward and a lottery reward on the quiz submission rates and accuracy of 112 college students. In Baseline, quizzes were for practice only and had no programmed contingency; in the Certain condition, two extra credit points were available for submission of a perfect quiz; and in the Lottery condition, students who submitted a perfect quiz were entered into a lottery with one winner (actual probability varied) for two points of extra credit. Submission rates averaged 36.50% for Baseline, 62.00% for Certain and 51.67% for Lottery. A one-way repeated measures ANOVA, followed by Fisher's LSD, found the differences in submission rates between all conditions to be significant at the .0001 level. Accuracy rates averaged 82.82% for Baseline, 93.80% for Certain and 93.99% for Lottery. A one-way repeated measures ANOVA, followed by Fisher's LSD found the mean score for the Baseline condition to be significantly lower than the mean scores for the Certain and Lottery conditions (p < .01), but did not find a significant difference between the latter two conditions (p < .05). This study demonstrates that when all other factors (e.g. magnitude) are equal, certain rewards are more effective than lottery rewards at increasing quiz submissions. It is possible that the lottery was less effective than the certain reward, due to the uncertainty (indirect contingency) inherent in the Lottery condition. These results have implications for business settings that use lottery rewards in an attempt to motivate a large number of employees at low costs. Future research should examine the roles of magnitude, probability and contingency in predicting the relative effectiveness of a lottery reward.
Discrimination of tone contrasts in Mandarin disyllables by naive American English listeners
Year of Dissertation:
2010
Program:
Speech & Hearing Sciences
The present study examined the perception of Mandarin disyllabic tones by inexperienced American English speakers. Participants heard two naturally-produced Mandarin disyllables, and indicated if the two were the same or different. A small native Mandarin-speaking control group participated as well. All 21 possible Mandarin contrasts where the initial syllable varied but the final syllable stayed the same were tested. Acoustic analysis was performed on the stimuli under study. Mandarin subjects scored at ceiling on all contrasts. American English subjects performed poorly on contrasts where the difference in mean F0 was small, or where the difference in the offset F0 of the first syllable was small. They also performed poorly when the difference in slope of the final syllable was small. Previous research has proposed that American English listeners attend primarily to the height difference between two tone stimuli, but here they attended to height in the first syllable and contour in the second syllable.
Fructose-conditioned flavor preferences in the rat: dopaminergic and opioid substrates in the nucleus accumbens and amygdala
Year of Dissertation:
2010
Systemic dopamine (DA) D1 (SCH23390) and D2 (raclopride) receptor antagonists reduce acquisition and expression of fructose-conditioned flavor preferences (CFP) in rats. Given DA involvement in nucleus accumbens shell (NAcS) and amygdala (AMY) in learning of food reward, the first and second aims examined whether NAcS or AMY D1 or D2 antagonism altered acquisition and expression of fructose-CFP. In expression, food-restricted rats with bilateral NAcS or AMY cannulae were trained to drink a flavored fructose (8%) and saccharin (0.2%) solution or another flavored 0.2% saccharin solution. Two-bottle tests with both flavors in saccharin solutions occurred 10 min following NAcS or AMY doses of 0, 12, 24 or 48 nmol of SCH23390 or raclopride. CFP expression following vehicle (76-77%) was significantly reduced by SCH23390 (48 nmol: NAcS, 62%; AMY, 66%) and raclopride (NAcS: 24 nmol, 63%; 48 nmol, 68%). In acquisition, rats received 12 nmol of SCH23390 (D1) or raclopride (D2) in the NAcS or AMY 10 min prior to one-bottle training sessions. Yoked controls received vehicle with limited CS intakes, whereas untreated controls were not injected or limited. Two-bottle tests revealed initial CFP in all groups that remained stable in untreated and yoked controls, but were lost over six test sessions in the AMY D1 and NAcS D1 and D2 groups. Thus, D1 and D2 receptor blockade in the NAcS and AMY significantly attenuated expression, but not initial acquisition of fructose-CFP, and hastened extinction of fructose-CFP.
The Effects of Changing Values of Concurrent Fixed Ratio Schedules on Mand Allocation in Children with Autism
Year of Dissertation:
2010
Teaching situations with children with autism usually involve concurrent schedules of reinforcement. During concurrent schedules, manipulation of the schedule of reinforcement for one response affects the occurrence of alternative responses. This study evaluated the effects of four sets of unequal and one set of equal concurrent fixed-ratio schedules on the allocation of two mands in three children with autism. All three participants emitted a higher rate of mands for a highly preferred item than for a less preferred item determined by an initial preference assessment during a concurrent FR1/FR1 schedule. All participants increased mands for the less preferred item when the schedule value for mands for the highly preferred item was at some value greater than FR1. In terms of behavioral economics, positive cross price demand for the less preferred item as a function of increasing FR values for mands for the highly preferred item showed that all three participants substituted a less preferred item for a highly preferred item. This substitution, along with a negative own price demand for the highly preferred item as a function of increasing FR values for mands for that item, indicated some degree of demand elasticity for the highly preferred item. In addition, an increase in response variability measured by the number of switches from one mand to the other accompanied the increase in mands for the less preferred item at FR values greater than FR1 for the highly preferred item for two of the three participants. Comparison of measures of demand elasticity to more traditional measures of matching and maximization show that the former provides a more detailed account of response allocation during concurrent schedules. These finding have implications for the use of behavioral economics in the analysis of behavior change interventions during concurrent schedules in applied settings where a single behavior occurs at an inappropriate frequency and in the absence of desirable alternative behaviors.
Individual Differences in Electric Fishes: An Animal Model of Personality
Year of Dissertation:
2011
Advisor:
Christopher Braun
Individual differences in animals have recently been described in behavioral ecology as behavioral syndromes: suites of correlated behaviors within individuals that are consistent across environmental situations. A central idea behind the behavioral syndromes approach is that behaviors do not occur in isolation; rather, they are integrated with other behaviors within the limited biological machinery of one individual. Electric fish are ideally suited for studies of behavioral syndromes because their behavior can be easily measured and tracked due to their unique electric organ discharges (EODs). It is also a good system to present realistic electric signals that mimic social interactions. Using a cohort of 22 Microsternarchus sp. a neotropical knifefish, we carried out a series of behavioral experiments, including a) a free exploration experiment, b) a terrestrial challenge, c) a novelty response experiment, d) a playback experiment with an aggressive sympatric species, and e) a jamming avoidance experiment. With the exception of the playback experiment, all were performed twice on all available individuals over the course of two years. Behavioral responses including EOD rate, locomotor activity, responses to novel as well as threatening stimuli, and reaction times were measured. Through principal components analysis and correlational analysis we determined that Microsternarchus sp. exhibit behavioral syndromes in activity, reactivity, aggression/dominance and possibly behavioral flexibility, integrating electric signaling behaviors with components of exploratory behavior and responses to stimuli. For example, individuals with the highest EOD rates spent more time swimming around a novel environment, than individuals with lower EOD rates, thus these behaviors form part of an activity syndrome.
STOCK'S PRICE BEHAVIOUR AROUND CORPORATE MERGER AND ACQUISITION ANNOUNCEMENTS: EVIDENCE FROM THE NYSE
Year of Dissertation:
2010
Efficient price discovery is one of the most important qualities of a financial market. Assessing a market's efficiency of price discovery is a challenging topic because efficient prices are not directly observable. It is not clear how to measure the extent to which actual prices conform to efficient prices. In this study, we use a methodology based on a state space model which deals naturally with short-term microstructure noise and enables the estimation of the unobservable prices and by implication, the pricing error. We investigate the contribution of non-instantaneous price discovery to intraday stock's price volatility around US corporate merger and acquisition announcements for a sample of 53 NYSE stocks from 2004 to 2008 using the TAQ data.
La poética del cuerpo en la obra de Carmen Cecilia Suárez
Author:
Luz Betancourt Aduén
Year of Dissertation:
2013
Program:
Hispanic & Luso Brazilian Literatures & Languages
In this Dissertation I reflected on the Poetics of the Body in the work of Carmen Cecilia Suárez, a contemporary Colombian writer and poet. I examined the literary influence of Un vestido rojo para bailar boleros (1988), which exposed the cultural patriarchal fabric that originates the colonized feminine subject in Colombia; and, in the achievement of this exposition, outstanding feminist literary critics of this country, such as María Mercedes Jaramillo, Angela Inés Robledo, Betty Osorio and Helena Araújo, were true sources of inspiration.
Being, Doing, Knowing, and Becoming: Science and Opportunities for Learning in the Out-of-School-Time Setting
Year of Dissertation:
2010
This dissertation addresses the question of how structured out-of-school-time settings, such as afterschool programs and summer camps, are positioned to support children's engagement and learning in science. This study addresses a gap in the research literature that does not fully specify the nature of the out-of-school-time (OST) setting and that generally does not position learning and development in relationship to one another, instead focusing on one or the other. As a result of an incomplete conceptualization of the OST setting as a site for learning and development, the OST field is becoming increasingly academicized, and its developmental qualities and benefits for children are under siege.