MicroRNAs (miRNA) are critical regulators of development, cell differentiation, and the stress response. Mature miRNAs are small (~22 nucleotides) RNA molecules that post-transcriptionally regulate their targets by acting as guides for Argonaute (AGO) proteins. Despite the importance of these small RNAs in many pathways, the rules of miRNA target site recognition remain unclear. Currently, nucleotides 2-8 of the miRNA, termed the ‘seed’ sequence, are known to be critical for miRNA targeting. However, it is unclear if families of miRNAs, which share the same seed sequence, functionally target the same target sites. To improve our understanding of miRNA targeting, I generated a unique and reproducible dataset through the ligation of miRNAs to their target sites using individual nucleotide-resolution crosslinking and immunoprecipitation (iCLIP) in the nematode worm Caenorhabditis elegans, which is detailed in Chapter 2.

As reviewed in Chapter 3, these ligated RNAs, called miRNA-target chimeras, provide biochemical evidence of which miRNAs are bound at a specific target site. Chapter 4 details my analysis of these chimeric data. Interestingly, the majority of miRNA target sites had the potential to support 3’ end interactions. In contrast to my prediction that these highly related miRNAs would bind the same sets of targets, family members from multiple miRNA families primarily targeted specific sets of transcripts. To confirm the importance of the 3’ end in vivo, I carried out in vivo rescue experiments that demonstrate that seed pairing is insufficient to mediate targeting in the absence of additional complementarity to nucleotides in the 3’ end of the miRNA. To confirm that 3’ end interactions direct binding specificity, I developed a novel method called ChimeraPCR (ChimP) that allowed for the detection of miRNA-target chimeras without the need for analyzing sequencing datasets.

To understand the role of AGO proteins in regulating lifespan in C. elegans, I generated several genetic tools, which are described in Chapter 5. These tools facilitated studies of how the highly related AGO proteins, ALG-1 and ALG-2, have opposing roles in controlling lifespan.

This report, Part II, constitutes the culmination of a research study which was described initially in a paper of the same Title, Part I, that appeared as SIO Reference 53-33, September 1953, and provides a further account of the mathematical theory involved in the determination of the electromagnetic field components generated by a horizontal electric dipole embedded in a conducting half-space separated from the non-conducting medium above by a horizontal plane. In particular, a detailed account is given of the computations involved for points of observation in the non-conducting medium when the depth of the source and the height of the point of observation are small in comparison with the horizontal range.

The first part of this report is concerned mainly with the general evaluation of the fundamental integrals for both media by the double saddle point method of integration developed earlier, and the salient feature of the present analysis is the fact that the new asymptotic expansions are term-wise differentiable to any order with respect to three essential parameters: horizontal range, depth (or height) of dipole source, and height (or depth) of the point of observation. It is shown that this important achievement is a consequence of applying the saddle point method of integration to a more judicious choice of exponent with the result that the asymptotic expansions presented here are much simpler than those reported in Part I.

The remainder of the report is concerned with the application of the new asymptotic expansions to the evaluation of the Cartesian components of the Hertzian vector and of the cylindrical components of the electromagnetic field vectors for points of observation in the non-conducting medium. Simplified approximations in which numerical substitutions can be readily made are presented for three distinct ranges corresponding to the asymptotic, the intermediate, and the near field; and, in each case, a detailed account is given of the power flow in the field. In addition, there is presented for the first time, for points of observation In the non-conducting medium, an approximation valid down to zero horizontal range, which is attained by equating to zero the propagation constant in the non-conducting medium. Numerical results are given in a manner similar to the numerical example presented in Part I.

This report gives a thorough and complete account of the mathematical problems involved in the determination of the electromagnetic field components generated by a horizontal electric dipole embedded in a conducting half-space whose plane boundary is also horizontal. The problem is formulated by introducing the Hertzian vectors or polarization potentials and employing the technique of triple Fourier transforms in Cartesian coordinates, in configuration space as well as in transform space. Suitable integral representations are obtained for the components of the Hertzian vectors.

It is shown that this formulation is fundamental in the sense that it contains 'per se’ all other known formulations of the problem. Thus, by suitable transformations of the variable or variables of integration one readily obtains the formulations of Sommerfeld (1909), Weyl (1919) , Ott (1942) , etc. Further, by correctly specifying the original path of integration in Sommerfeld’s formulation of the problem and by carefully analyzing the class of permissible deformations of the original path, the whole moot question of poles and residues is clarified in a straightforward manner.

The report also presents the complete independent solution of the static problem and it is shown that all solutions for the alternating case converge uniformly to the static solutions as the frequency is made to vanish. Further, the static solution is applied to an extended source pointing out the way for a similar extension of the alternating dipolar solution.

The Cartesian components of the Hertzian vectors and the cylindrical components of the field vectors (E and H) are given, for both media, in terms of four fundamental integrals, which are expanded in asymptotic series by saddle point methods, two of these integrals belonging to the conducting medium and the other two to the free space above. It is shown, in the treatment of each of the four integrals mentioned, that there are two distinct asymptotic contributions arising from two saddle points and the notable feature of the results is that one of the saddle points yields a solution which is not exponentially attenuated in the horizontal direction in accordance with known experimental results. Thus, the possibility of large ranges of the field in the horizontal direction at depths which are not too great is clearly established.

The work contained within this dissertation describes the synthesis and study of a series of molecular complexes that mimic the connectivity and geometry of active sites in heterogeneous catalysis. The molecular complexes serve two purposes; they serve as models of surface sites for spectroscopic comparison to metals sites on silica described in the literature and as thermolytic molecular precursors to new materials and isolated metal centers on silica supports by the thermolytic molecular precursor (TMP) method. This dissertation focuses on the development of molecular precursors and model complexes based on group 13 and 14 elements which can be used to model or generate metal sites with relevance to catalysis. In chapter one, methods are explored and developed to control the nuclearity of gallium metal centers in silica materials formed by direct decomposition of molecular precursors which influences their acidity and coordination environments. In chapter two, novel molecular models of catalytic sites reported in the literature are synthesized, characterized and used to investigate proposed initiation steps in heterogeneous catalysis. Finally, chapter three explores new molecular precursors for doping metal centers on silica with germanium, which has previously been shown to influence catalysis.

Chapter one describes the use of a new molecular precursor, Ga[OSi(OtBu)3]3•THF, to generate gallium-containing silica materials by direct thermolysis of the molecular precursor dissolved in a hydrocarbon solvent. The use of a block co-polymer, P-123 Pluronic, as templating agent during thermolysis was investigated in conjunction with the inclusion of tris(tert-butoxy)silanol as a co-thermolysis partner. Co-thermolysis was pursued to tune the Ga:Si ratio of the resulting materials, denoted UCB1-GaSiX. When P-123 pluronic was added as a template in the direct thermolysis of Ga[OSi(OtBu)3]3•THF, the resulting material displayed uniform vermicular pores. However, a decrease in the uniformity of these vermicular pores and eventual generation of primarily textural mesoporosity was found as the gallium content of the final material was decreased through co-thermolysis with tris(tert-butoxy)silanol. It was observed by powder X-ray diffraction and 71Ga MAS-NMR that the inclusion of tris(tert-butoxy)silanol in the precursor mixture also affected the geometry and state of gallium; elimination of observable gallium oxide domains and formation of proposed isolated sites as the gallium content of the material decreased is reported.

Chapter two describes the synthesis and characterization of a series of gallate and aluminate complexes containing M–O–SiO3 linkages that mimic two important sites in zeolite chemistry; framework sites with the structure M[–O–SiO3]4–, and partially-hydrolyzed framework sites with the structure HOM[–O–SiO3]3–. These anionic complexes were paired with Li(12-Crown-4)x cations to form charge-separated or weakly-associated cation-anion pairs. Single-crystal X-ray diffraction studies, vibrational spectroscopy, NMR spectroscopy and EXAFS predictions were performed in order to place the synthesized complexes within the context of zeolite literature and molecular models of group 13 metals in silica previously reported. An investigation of the reactivity of the models for partially-hydrolyzed framework sites, HOM[–O–SiO3]3–, with alcohols was performed and showed formation of ROM[–O–SiO3]3– structures in analogy with proposed initiation steps in the formation of active species for Meerwin-Ponndorf-Verley (MPV) transfer hydrogenation catalysts.

Chapter three describes the generation of a new ligand precursor for the synthesis of thermolytic molecular precursors to tertiary metal oxides containing first-row transition metals, germanium and silicon. The synthesis of iron-, chromium- and manganese-based precursors is described and their thermolytic behavior is investigated. These precursors undergo thermolysis at moderate temperatures and were investigated for the deposition of germanium and transition metal atoms onto a silica support. The grafting of these precursors onto silica was explored and the resulting surface species were probed by EPR and NMR spectroscopies. The grafted materials were calcined to remove organic residues and the changes in the resulting surface species from the grafted precursors was investigated by UV-vis and EPR spectroscopies. The resulting calcined materials were compared to Fe, Mn, and Cr centers deposited in the absence of germanium for their catalytic activity in alcohol oxidation and alkene epoxidation, however, in cases where catalytic activity was observed, the activity was indistinguishable between germanium-doped and un-doped materials for a given metal center. Possible explanations for this are provided and related to prior work on the TMP method in order to be illustrative of the successes and potential limitations of molecular precursor design for generation of new materials.

This study examines the experiences of five Egyptian undergraduate students at the American University in Cairo (AUC) from different educational, class and geographic backgrounds. This study finds that students from public schooling and lower socioeconomic backgrounds arrive at AUC with significant language, literacy and social deficits compared to counterparts from private schooling and high socioeconomic backgrounds. The study considers how participants, based on the backgrounds, become involved with transnational literacy practices in university writing assignments. The study draws upon scholarship in transnational literacy studies, to inflect how New Literacy Studies considers global and local literacies with concepts of capital and positionality drawn from Pierre Bourdieu. The study conceptualizes student educational and class backgrounds as forms of cultural and social capital which, when deployed at AUC, result in differing participant positionality along educational and class lines. Although this distribution creates challenges for students from public schooling backgrounds, the study also finds that a student from a public schooling background exhibited unusually adaptive qualities, resulting in novel approaches to completing a complex literacy task. The study concludes by arguing that transnational literacy studies be extended to account for intranational movements within uniquely configured embedded, hybrid and permeable transnational spaces that serve local interests.

In the modern Lambda-CDM model of cosmology, galaxies form in the centers of overdense regions in the cosmic web, known as dark matter halos. The formation and evolution of galaxies are believed to be connected to the formation and evolution of the halos they occupy. This concept is referred to as the galaxy--halo connection, and it provides us with an avenue for understanding the complex physics involved in galaxy formation. Because we assume every galaxy is located in the center of a halo, drawing parallels between the spatial distributions of galaxies and halos is an effective way of illuminating how halo properties may be connected to galaxy properties. However, three-dimensional spatial information is difficult to obtain accurately in the real Universe, as all information must be extracted from the emitted light of distant galaxies. In this paper, we apply the stochastic order redshift technique (SORT) to mock redshift surveys to test how well it recovers the true distribution of galaxies. SORT relies on a small (10%) reference sample of high-quality redshifts that outline the underlying structure of galaxies to determine new estimates of low-quality redshifts. We find that SORT overall improves redshifts, recovers the redshift-space clustering on scales > 2.5 Mpc/h, and provides improved estimates of local densities. Then, we study the clustering properties of central SDSS galaxies as a function of specific star formation rate (sSFR). We find that central galaxy auto-correlations show little dependence on sSFR, with the established result of quiescent galaxies clustering more strongly than star-forming galaxies attributable to satellites. Because halo assembly history is known to affect distinct halo clustering, this result implies there is little net correlation between halo assembly history and central galaxy sSFR. We also find that cross-correlations of centrals with satellites increase with lower sSFR, suggesting that quiescent centrals have more satellites than star-forming centrals of the same mass. We compare our findings to the predictions of empirical models of sSFR using the Bolshoi-Planck N-body simulation and find that models dependent on halo assembly history disagree with observations while a model independent of halo assembly history reproduces well the observed clustering properties of centrals.

This dissertation analyzes the centrality of the concept Bildung in the portrayal of the development of class consciousness in novels and autobiographical texts written by socialist and communist authors in France and Germany from 1890 to 1938. These texts follow Lukàcs’ typology for the Bildungsroman laid out in The Theory of the Novel, but significantly modify the reconciliation Lukàcs imagines for the problematic individual by deferring it to a post-revolutionary future. Class consciousness emerges out of these developmental paths, which include a negation of initial Bildung and a second-order, political Bildung that discloses the identity of the individual and the class through a recognition of shared material determinants. The first chapter examines the relationship between Bildung, associative life, and the early literary politics of the Socialist Party of Germany (SPD) and shows the importance attributed to Bildung by the German workers’ movement in an effort to reconsider the merits of these workers’ mediations and their relationship to the reproduction of capital at this particular historical moment. The second chapter reads the autobiographical life-writings of the Adelheid Popp, Wenzel Holek, Franz Rehbein, Theodore William Bromme, and Otto Krille as Arbeiterbildungsromane and argues that these texts show class consciousness to be inextricable from high levels of industrial employment. The third and fourth chapters examine the work of the French communist novelist, journalist, and philosopher Paul Nizan. Chapter three argues that Nizan’s concept of alienation as alienation from l’homme informs his portrayal of the development of political consciousness by allowing him to see the alienation of intellectuals as analogous to the alienation experienced by workers in capitalist production. Chapter four argues that Nizan’s Antoine Bloyé and La conspiration suggest that political consciousness is unlikely to develop without its material determinants.