In 2007, juveniles were involved in a minimum of 1,063 murders in the United States (Federal Bureau of Investigation, 2008), and a concern over juvenile homicide offenders remains. While increasingly more macrolevel research on juvenile homicide offending has been accumulated, particularly since the 1980s, research focusing on macrolevel correlates of juvenile homicides is still relatively scarce (MacDonald & Gover, 2005; Ousey & Campbell Augustine, 2001). In the first part of this study, several variables relating to the offender, victim, setting, and precursors to the homicide by race and gender were examined in order to provide details on the context of youth homicides between 1965 and 1995 in Chicago. The Homicides in Chicago, 1965-1995 data set and Census data for 1970, 1980, and 1990 were used in this study. The results indicate that changes in youth homicides over the 31-year time period involved increases in lethal gang altercations, particularly among Latinos, and increases in the use of automatic weapons. Young females had very little impact on homicide rates in Chicago. The second part of the study examined whether measures of social disorganization can aid in the prediction of homicides committed by youths, and a total of ten negative binomial models were run. The results of the analyses in the three time periods indicate that racial/ethnic heterogeneity, educational deprivation, unemployment, and family disruption are significantly and positively related to homicides. Foreign-born population and median household income were found to be significantly and negatively related to homicides. The significant indicators of social disorganization varied in the seven models for the disaggregated groups. Overall, the results reflect support for social disorganization theory. Limitations, suggestion for future research, and policy implications are also addressed.

Fear of crime is argued to be a social problem that may lead to restriction of activities, increased security costs, and avoidance behaviors. Findings from research indicate that there are many demographic influences on the fear of crime. Specifically, gender has been found to be one of the most consistent predictors of crime, that is, females significantly fear crime more than males. Additionally, research suggests that a person's fear of crime or perceived risk to crime may increase their engagement in precautionary behaviors, such as carrying a weapon for protection. The current study examined these relationships using data collected from 588 students at the University of Central Florida in the fall of 2006. The results indicated that females reported significantly higher mean scores on the fear scale for all crimes except property crimes, as well as higher mean scores for most crimes on the perceived risk of victimization scale. Females also reported feeling less safe from crime in their neighborhood and at home. Furthermore, females were more likely to engage in precautionary behaviors, but less likely to engage in risky behaviors. Fear of crime was not a significant predictor of the use of precautionary behaviors. However, respondents with greater perceived risk were more likely to use a greater number of precautionary behaviors. Additionally, respondents who had a perceived lack of safety were more likely to use precautionary behaviors and engage in them more often. Risky lifestyle behaviors were not significant predictors of either fear or guardianship activities. Exposure to the media was only shown to increase fear, perceived risk, and perceived lack of safety at the bivariate level. And finally previous victimization was not a significant predictor of fear or perceived risk. Overall, the results were fairly consistent with previous literature. Implications for future research and policy are discussed.

The primary focus of this dissertation is the development of novel fluorescent near-infrared molecules for various applications. In Chapter 1, a compound dU-BZ synthesized via Sonogashira coupling reaction methodology is described. A deoxyuridine building block was introduced to enhance hydrophilic properties and reduce toxicity, while an alkynylated benzothiazolium dye was incorporated for near-IR emission and reduce photodamage and phototoxicity that is characteristic of common fluorphores that are excited by UV or visible light. A 30-fold enhancement of fluorescence intensity of dU-BZ was achieved in a viscous environment. Values of fluorescence quantum yields in 99% glycerol/1% methanol (v/v) of varying temperature from 293 K to 343 K, together with fluorescence quantum yields, radiative and nonradiative rate constants and fluorescence lifetimes in glycerol/methanol solutions of varying viscosities from 4.8 to 950 cP were determined. It was found that both fluorescence quantum yields and fluorescence lifetimes increased with increasing viscosity, which is consistent with results predicted by theory. This suggests that the newly designed compound dU-BZ is capable of functioning as a probe of local microviscosity, and was later confirmed by in vitro bioimaging experiments. In Chapter 2, a new BAPTA (O,O*-bis(2-aminophenyl)ethyleneglycol-N,N,N*,N*-tetra acetic acid) and BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based calcium indicator, BAPBO-3, is reported. A new synthetic route was employed to simplify both synthesis and purification, which tend to be low yielding and cumbersome for BAPTA derivatives. Upon excitation, a 1.5-fold increase in fluorescence intensity in buffer containing 39 ?? Ca2+ and a 3-fold increase in fluorescence intensity in buffer containing 1 M Ca2+ was observed; modest but promising fluorescence turn-on enhancements. In Chapter 3, a newly-designed unsymmetrical squaraine dye, SQ3, was synthesized. A one-pot synthesis was employed resulting in a 10% yield, a result that is generally quite favorable for the creation of unsymmetrical squaraines Photophysical and photochemical characterization was conducted in various solvents, and a 678 nm absorption maximum and a 692 nm emission maximum were recorded in DMSO solution with a fluorescence quantum yield of 0.32. In vitro cell studies demonstrated that SQ3 can be used as a near-IR probe for bioimaging.

In survival analysis, proportional hazards model is the most commonly used and the Cox model is the most popular. These models are developed to facilitate statistical analysis frequently encountered in medical research or reliability studies. In analyzing real data sets, checking the validity of the model assumptions is a key component. However, the presence of complicated types of censoring such as double censoring and partly interval-censoring in survival data makes model assessment difficult, and the existing tests for goodness-of-fit do not have direct extension to these complicated types of censored data. In this work, we use empirical likelihood (Owen, 1988) approach to construct goodness-of-fit test and provide estimates for the Cox model with various types of censored data. Specifically, the problems under consideration are the two-sample Cox model and stratified Cox model with right censored data, doubly censored data and partly interval-censored data. Related computational issues are discussed, and some simulation results are presented. The procedures developed in the work are applied to several real data sets with some discussion.