Educating for Change: How Leadership Education and Training Affect Student Activism in Lesbian, Gay, and Bisexual Undergraduates

This thesis explored the extent to which leadership education and training experiences predicted student activism in lesbian, gay, and bisexual undergraduate students. The impact of these experiences were compared to the impact of participants' involvement and leadership in co-curricular and off-campus organizations to identify the additional ways that leadership education and training can supplement a student's organizational participation in encouraging student activism for this student population. Data from 2,681 students who identified as lesbian, gay, or bisexual on the Multi-Institutional Study of Leadership were used for this study. A single hypothesis was tested using the College Impacts model as the conceptual framework, and multiple regression was the chosen statistical method. The model established for this study explained 51.3% of the observed variance in student activism with demographic variables, pre-college experiences, organizational participation, and leadership education and training experiences serving as positive predictors

Damages Recoverable for Wrongful Death

The Virginia Legislature at the 1968 session of the General Assembly amended Section 8-636 of the Code of Virginia and thereby altered drastically both the amount and the method of distribution of damages recoverable under Virginia\u27s Wrongful Death Act.\u27 Only the section dealing with damages and the distribution thereof was altered, but the amendment changed substantially those entitled to an award of damages for financial or pecuniary loss and the conditions prerequisite to recovery for such loss

COMPACT REPRESENTATIONS OF UNCERTAINTY IN CLUSTERING

Flat clustering and hierarchical clustering are two fundamental tasks, often used to discover meaningful structures in data, such as subtypes of cancer, phylogenetic relationships, taxonomies of concepts, and cascades of particle decays in particle physics. When multiple clusterings of the data are possible, it is useful to represent uncertainty in clustering through various probabilistic quantities, such as the distribution over partitions or tree structures, and the marginal probabilities of subpartitions or subtrees. Many compact representations exist for structured prediction problems, enabling the efficient computation of probability distributions, e.g., a trellis structure and corresponding Forward-Backward algorithm for Markov models that model sequences. However, no such representation has been proposed for either flat or hierarchical clustering models. In this thesis, we present our work developing data structures and algorithms for computing probability distributions over flat and hierarchical clusterings, as well as for finding maximum a posteriori (MAP) flat and hierarchical clusterings, and various marginal probabilities, as given by a wide range of energy-based clustering models. First, we describe a trellis structure that compactly represents distributions over flat or hierarchical clusterings. We also describe related data structures that represent approximate distributions. We then present algorithms that, using these structures, allow us to compute the partition function, MAP clustering, and the marginal proba- bilities of a cluster (and sub-hierarchy, in the case of hierarchical clustering) exactly. We also show how these and related algorithms can be used to approximate these values, and analyze the time and space complexity of our proposed methods. We demonstrate the utility of our approaches using various synthetic data of interest as well as in two real world applications, namely particle physics at the Large Hadron Collider at CERN and in cancer genomics. We conclude with a brief discussion of future work

Stability of High-Speed, Three-Dimensional Boundary Layers

Boundary-layer experiments are performed in the low-disturbance, Mach 6 Quiet Tunnel (M6QT) at Texas A&M University. The experiments are focused specifically on investigating the physics of two three-dimensional phenomena in hypersonic boundary-layer stability and transition: the breakdown of second-mode waves and the growth and breakdown of crossflow waves. In order to enable these experiments, a new, three-dimensional probe traversing mechanism was designed and constructed. In order to investigate the breakdown of second-mode waves, experiments are conducted on a flared cone with a 5° half angle at the tip at zero angle of attack. Experiments were typically performed at unit Reynolds number Re’ ≈ 10 × 10^6/m with a slightly hot wall, T/Taw ≈ 1.05. A new, durable method of roughness element application is discussed for the purpose of exciting the unstable waves. Hot-wire measurements were made of the boundary layer and it is shown that even with roughness elements, transition to turbulence does not occur on the model. Therefore, the expected Λ vortices are not observed. The crossflow instability in a hypersonic boundary layer is studied on a 7° right circular cone at 5.6° angle of incidence. Experiments were performed at Re’ ≈ 10 × 10^6/m with an adiabatic wall. Hot wire measurements are made at a series of axial locations to generate contours of streamwise mass flux. The stationary vortex structure is shown through its saturation. Traveling waves are observed in the expected frequency range, 10 kHz to 60 kHz, predicted by computations and are located generally in the high-speed troughs in the vortex structure. Secondary instability is observed between 80 kHz and 130 kHz. Frequency scaling and location is shown to agree with low-speed experiments and good preliminary agreement with hypersonic computations is obtained. Transition does not naturally occur on the model. Distributed roughness is applied to the tip in order to excite crossflow and cause transition. Transition is shown to occur with the rough tip, but is not likely a result of crossflow

The cloning and characterisation of the chicken tyrosinase-related protein gene family

Very little is known about the molecular and genetic mechanisms controlling pigmentation within the bird kingdom. The aim therefore, of this study was to contribute towards the understanding of the genetic regulation of avian pigmentation by the cloning and characterisation of the chicken Tyrosinase-related protein (TRP) gene family. To accomplish this goal, neural crest cells from 500 black chick embryos were cultured under conditions supportive of melanocyte differentiation and proliferation. Using RNA extracted from these pigmented melanocyte cultures, a novel embryonic chick cDNA library was constructed. Screening of this library for chicken equivalents of the mammalian TRP gene family yielded more than 200 cDNA clones. After sequencing, three of these clones, 88.3, pcTRP- 1.6 and pcTRP -2. 10, were found to encode chicken Tyrosinase (Tyr), Tyrosinase-related protein-1 (Tyrp1) and Tyrosinase-related protein-2 (Tyrp2), respectively. In addition, a chicken Microphthalmia (Mi) cDNA clone (M156) was isolated using a mouse Mi cDNA probe. Comparative analyses revealed that chicken Tyr, Tyrp1 and Tyrp2 share approximately 68%, 72% and 70% amino acid sequence identity with their vertebrate orthologues. Northern blot hybridisation analysis demonstrated that the chicken TRPs are expressed in RNA from cultured retinal pigment epithelial (RPE) cells as well as in whole eye RNA. The major transcript sizes for the chicken Tyr, Tyrp1 and Tyrp2 genes are 2.5 kb, 2.3 kb and 3.5 kb, respectively. In situ hybridisation studies confirmed that both chicken Tyr and Tyrp2 genes are expressed in a pigment cell-specific fashion with signals detected in both the skin and RPE of chick embryos. Genomic Southern blot hybridisation analyses strongly suggested that all three chicken TRP genes contain several introns that are likely to be conserved within the vertebrate TRP gene family. Furthermore, the chick Tyr, Tyrp1 and Tyrp2 genes were found to span approximately 5-19 kb, 5-11 kb and 15-30 kb, respectively of the chicken genome. Comparisons between a black and white chick breed at the Tyr and Tyrp1 loci revealed no gross rearrangements at either of these loci. However, 1-2 kb alterations were observed between the same breeds at the Tyrp2 locus. The nature and significance of this alteration is not known. The cloning of the chicken Tyr, Tyrp1 and Tyrp2 cDNAs constitutes the first molecular cloning and characterisation of any avian TRP gene family. Taken together therefore, this study contributes towards the further understanding of the molecular mechanisms regulating pigmentation as well as the evolution of gene families

Social and familial risk factors for drinking initiation and affective response to marijuana use

Thesis (Ph.D.)--Boston UniversityEarly initiation of substance use increases risks for abuse, injury, dependence, and death for young people around the globe . When substances are used for affect regulation, there is a risk of escalating use. This dissertation examines social and familial risk factors for initiation of alcohol use, and the affective response to marijuana use in naturalistic settings. In study #1, we explored the prospective association between television advertising for alcoholic beverages, changes in alcohol expectancies, and initiation of drinking over 12 months. We found that alcohol expectancies and the odds of drinking initiation increased over 12 months as a non-linear function of advertising exposure for boys. In study #2, we examined the association between adolescent freedoms and drinking initiation. We found that adolescents who were free to set their own bedtimes on weeknights had (odds ratio, 95% confidence interval) 1.53 (1.27, 1.86) higher odds of drinking initiation. We found that associations varied by sex for freedoms regarding companionship and weekend curfews. Notably, we found that boys who were granted the freedom to choose their own time to come home on weekends had 0.63 (0.47-0.85) times lower odds of drinking initiation within 12 months while girls had 1.30 (0.97-1 .73) times increased odds. In study #3 , we used both correlated data analysis methods and a case- crossover design to analyze data from an Ecological Momentary Assessment study examining changes in momentary affect following marijuana use. We found that negative affect was higher following marijuana use compared to backg round times, except for times when marijuana was being used to cope or conform. We found positive affect increased following marijuana use for persons with cannabis dependence but decreased otherwise. Further, we found that extremes of negative and positive affect were more likely to be experienced following marijuana use relative to background time periods. Our findings regarding alcohol advertising may inform efforts to ban alcohol advertising in countries including Finland and South Africa, while the findings relating to adolescent freedoms may improve parent education programs regarding underage drinking. Finally, improved understanding of the affective response to marijuana use may improve treatment programs

Predicting individual book use for off-site storage using decision trees

We explore various methods for predicting library book use, as measured by circulation records. Accurate prediction is invaluable when choosing titles to be stored in an off-site location. Previous researchers in this area concluded that past use information provides by far the most reliable predictor of future use. Because of the computerization of library data, it is now possible not only to reproduce these earlier experiments with a more substantial data set, but also to compare their algorithms with more sophisticated decision methods. We have found that while previous use is indeed an excellent predictor of future use, it can be improved upon by combining previous use information with bibliographic information in a technique that can be customized for individual collections. This has immediate application for libraries that are short on storage space and wish to identify low-demand titles to move to remote storage. For instance, simulations show that the best prediction method we develop, when used as the off-site storage selection method for the Harvard College Library, would have generated only a fifth as many off-site accesses as compared to a method based on previous use.Engineering and Applied Science

Mitochondrial heat shock protein 70, a molecular chaperone for proteins encoded by mitochondrial DNA

Mitochondrial heat shock protein 70 (mt-Hsp70) has been shown to play an important role in facilitating import into, as well as folding and assembly of nuclear-encoded proteins in the mitochondrial matrix. Here, we describe a role for mt-Hsp70 in chaperoning proteins encoded by mitochondrial DNA and synthesized within mitochondria. The availability of mt-Hsp70 function influences the pattern of proteins synthesized in mitochondria of yeast both in vivo and in vitro. In particular, we show that mt-Hsp70 acts in maintaining the var1 protein, the only mitochondrially encoded subunit of mitochondrial ribosomes, in an assembly competent state, especially under heat stress conditions. Furthermore, mt-Hsp70 helps to facilitate assembly of mitochondrially encoded subunits of the ATP synthase complex. By interacting with the ATP-ase 9 oligomer, mt-Hsp70 promotes assembly of ATP-ase 6, and thereby protects the latter protein from proteolytic degradation. Thus mt-Hsp70 by acting as a chaperone for proteins encoded by the mitochondrial DNA, has a critical role in the assembly of supra- molecular complexes

The Kinetics of Electrosterically Stabilized Emulsion Polymerization Systems

The kinetics of electrosterically stabilized emulsion systems was studied. The aim of this was to understand the impact that steric and electrosteric stabilizers have on the kinetics of particle growth and particle formation in the area of emulsion polymerization. The well-established mechanisms that govern these processes for emulsions stabilized by conventional low molecular weight surfactants were used as a reference point for comparative purposes. Model latexes were synthesized that comprised of a poly(styrene) core stabilized by a corona of poly(acrylic acid). The advent of successful controlled radical polymerization techniques in heterogeneous media (via RAFT polymerization) allowed for latexes to be synthesized under molecular weight control. For the first time, the degree of polymerization of the stabilizing block on the particle surface was able to be controlled and verified experimentally using mass spectrometry techniques. Three latexes were made with different average degrees of polymerization of the stabilizing block; five, ten and twenty monomer units respectively. A methodology was developed to remove the RAFT functionality from the polymer chains present in the emulsion while retaining the desired particle morphology. Oxidation with tertbutylhydroperoxide (TBHP) was proven to be successful at eliminating the living character provided by the thiocarbonyl end-group. Extensive dialysis and cleaning of the latex was performed to ensure no residual TBHP or reaction by-products remained. Latexes with poly(styrene) cores were chosen for this work as poly(n-butyl acrylate) latexes were shown to be influenced by chain transfer to polymer, providing an additional kinetic complication. The three electrosterically stabilized emulsions were used as seed latexes in carefully designed kinetic experiments to measure the rate of polymerization as a function of time. Two independent techniques (chemically initiated dilatometry and γ-relaxation dilatometry) were used to measure the rate coefficients of radical entry (ρ) and exit (k) in these systems – the two parameters that essentially govern the rate of particle growth. The latexes were chosen such that they satisfied ‘zero-one’ conditions (i.e. that any given latex particle contains at most one growing radical at any given time) in order to simplify data analysis. Three different chemical initiators were used, each yielding a radical with a different electric charge. Results from γ-relaxation experiments demonstrated that the three electrosterically stabilized latexes gave very long relaxation times when removed from the radiation source, ultimately yielding very small k values. These values were up to a factor of 10 smaller than that predicted by the ‘transfer-diffusion’ model for exit for particles of that size. This reduction was attributed to a ‘restricted diffusion’ effect, where the exiting monomeric radical has to diffuse through a dense layer of polymer on the particle surface, where its mobility will be restricted. Modification of the Smoluchowski equation for diffusion-controlled adsorption/desorption to account for this postulate led to the development of a model that gave excellent semi-quantitative agreement with experiment. Chemically initiated dilatometric experiments (using three different types of initiator) gave the unusual result of very low reaction rates and low steady-state values of 'nbar', the average number of radicals per particle. Using the standard kinetic equations for styrene-based systems (where it is assumed that an exited monomeric radical undergoes re-entry), this led to the calculation of impossibly small values of the entry rate coefficient ρ (far below any background or ‘thermal’polymerization rate). However upon removing the assumption of re-entry and assuming that exited radicals undergo termination, the obtained values of ρ were in almost perfect agreement with the values predicted from the ‘control by aqueous phase growth’ entry mechanism. This unexpected result was attributed to chemical reaction with the poly(acrylic acid) stabilizers through chain transfer to polymer (via hydrogen-atom abstraction). This postulate was verified by separate experiments that demonstrated that poly(acrylic acid) could act as a reasonably efficient chain transfer agent for styrene polymerization. The addition of poly(acrylic acid) to the aqueous phase of a conventionally stabilized emulsion also led to the rate reduction seen previously. NMR experiments demonstrated the existence of poly(acrylic acid-graft-styrene), which could only be formed through termination of a poly(styrene) chain with a poly(acrylic acid) chain bearing a mid-chain radical (as the product of a chain transfer reaction). These additional terms of transfer and termination were included in the governing kinetic equations of emulsion systems (the Smith-Ewart equations) to develop a model to account for the behaviour of electrosterically stabilized latexes. The ultimate fate of an exiting radical was now shown to be a competition between fates; successful desorption into the aqueous phase, or chemical reaction (through transfer or termination) within the hairy layer. These additional terms were shown to significantly reduce the theoretical value of nbar, and were in excellent agreement with experiment. For small electrosterically stabilized particles with a densely packed ‘hairy layer,’ it was seen that transfer/termination is the dominant loss mechanism as opposed to desorption. The developed model showed that as the particle size was increased, the dominant loss mechanism once again became successful desorption into the aqueous phase. The model was shown to give excellent agreement with experimental data from ‘uncontrolled’ emulsion systems. To explain the highly unusual secondary nucleation behaviour seen in systems such as these, it was postulated that beta-scission of a poly(acrylic acid) chain bearing a mid-chain radical is an important mechanistic step in the nucleation mechanisms of these systems. Modelling (both steady-state and time-dependent) gave good agreement with experiment with a minimal number of adjustable parameters. Theory (and supporting experimental evidence) demonstrated that this nucleation mechanism is only significant at high particle numbers; under other conditions the well-known ‘homogeneous nucleation’ mechanism is once again dominant