EXTRACELLULAR VESICLES IN OVARIAN ANTRAL FOLLICLES: CHARACTERIZATION AND FUNCTIONS

Formation of the follicular fluid antrum within the ovarian follicle provides a unique environment for the developing oocyte. Follicular fluid contains factors including nucleic acids, proteins, lipids, hormones, and metabolic factors secreted by both ovarian somatic cells and the oocyte that are critical for follicle development. In addition, lipid bi-layer extracellular vesicles (EVs) comprised of exosomes and microvesicles are highly abundant in follicular fluid. Whether these EVs play a role in ovarian cell signaling, provide a mechanism for transport of metabolic products or are nonfunctional within the ovarian follicle is unknown. In this dissertation, I will test the hypothesis that ovarian follicular fluid EVs are unique and determine whether they can elicit functional effects on the cumulus-oocyte-complex and the mural granulosa cells. To accomplish these goals, follicular fluid from three different sizes of bovine antral follicles, [i.e. small (3-5 mm), medium (6-9 mm), and large (9 mm)] were collected and EVs were isolated and characterized by electron microscopy, nanoparticle tracking analysis (NTA), protein marker analysis, and small RNAseq. Electron microscopy and NTA indicated the presence of a uniform (50-200 nm) population of EVs that had different microRNA within them based on follicle size. An EV marker, CD81, showed decreased abundance in EVs as follicle size increased. Fluorescent labeling of the follicular fluid EVs followed by culture indicated that both cumulus and mural granulosa cells took up the fluorescent-labeled EVs. To test for functional activity, cumulus-oocyte-complexes and granulosa cells were exposed to EVs isolated from different size follicles. Extracellular vesicle treatment caused expansion of cumulus cells and increased expression of prostaglandin-endoperoxide synthase 2 (Ptgs2), pentraxin-related protein 3 (Ptx3), and tumor necrosis factor, alpha-induced protein 6 (Tnfaip6) genes, genes associated with normal cumulus expansion. Additionally, EVs from small follicles induced granulosa cell proliferation, and we determined that the Src and JNK pathways were involved in the cell proliferation induced by EVs. Moreover, we determined that the differential ability of EVs to affect granulosa cell proliferation was primarily a result of preferential uptake by EVs from small follicles versus those of medium and large follicles. In summary, these studies provide insight into the unique characteristics of EVs isolated from three different stages of antral follicles. This work also provides the first functional evidence that EVs from ovarian follicular fluid are able to elicit functional physiologic changes in both cumulus and granulosa cells and provides clues to the cell signaling pathways that are modulated in cells following exposure to these small lipid enclosed vesicles. Lastly, this study provides an approach to further purify EVs, and indicates the ovarian follicle as an excellent model for studying general extracellular vesicle biology

Kruskal--Katona-Type Problems via Entropy Method

In this paper, we investigate several extremal combinatorics problems that ask for the maximum number of copies of a fixed subgraph given the number of edges. We call this type of problems Kruskal--Katona-type problems. Most of the problems that will be discussed in this paper are related to the joints problem. There are two main results in this paper. First, we prove that, in a $3$-colored graph with $R$ red, $G$ green, $B$ blue edges, the number of rainbow triangles is at most $\sqrt{2RGB}$, which is sharp. Second, we give a generalization of the Kruskal--Katona theorem that implies many other previous generalizations. Both arguments use the entropy method, and the main innovation lies in a more clever argument that improves bounds given by Shearer's inequality.Comment: 18 page

Tight Bound and Structural Theorem for Joints

A joint of a set of lines $\mathcal{L}$ in $\mathbb{F}^d$ is a point that is contained in $d$ lines with linearly independent directions. The joints problem asks for the maximum number of joints that are formed by $L$ lines. Guth and Katz showed that the number of joints is at most $O(L^{3/2})$ in $\mathbb{R}^3$ using polynomial method. This upper bound is met by the construction given by taking the joints and the lines to be all the $d$-wise intersections and all the $(d-1)$-wise intersections of $M$ hyperplanes in general position. Furthermore, this construction is conjectured to be optimal. In this paper, we verify the conjecture and show that this is the only optimal construction by using a more sophisticated polynomial method argument. This is the first tight bound and structural theorem obtained using this method. We also give a new definition of multiplicity that strengthens the main result of a previous work by Tidor, Zhao and the second author. Lastly, we include some discussion on the constants for the joints of varieties problem.Comment: 39 page

Family firm and analyst forecasts in an emerging economy

Purpose: The purpose of this paper is to examine how family firms affect analyst forecast dispersion, accuracy and optimism and how earnings smoothness as the moderating factor, affects these relationships in an emerging market context. Design/methodology/approach: This paper uses the population sample of firms listed on the Taiwan Stock Exchange from 2009 to 2010 as the research sample, which includes 963 firm-year observations. Findings: The findings show that analysts following family firms are more likely to have more dispersed, less accurate and more optimism biased forecasts than those following nonfamily firms. Earning smoothness is mainly used by nonfamily firms as a signalling strategy to improve analyst forecast quality. In contrast, earnings smoothness is mainly used by families as a garbling strategy, stimulating forecast optimism. Only earnings smoothness in family firms with a high level of family ownership concentration is likely to be signalling-oriented to improve analyst forecast accuracy and mitigate analyst optimism biases. Originality/value: Emerging markets are not only featured by prevailing principal-principal conflicts but also have multiple levels of agency conflicts among large shareholders, minority shareholders and professionally hired managers. This research reveals the multiple governance roles of family owners in affecting analyst forecast quality, including their entrenchment role in extracting private benefits of control through opaque environments and market discipline distortion role in aligning interests between managers and families without prioritising meeting or beating analyst forecasts, both at the cost of minority shareholders. This research further disentangles the intertwined signaling oriented and garbiling oriented incentives associated with earnings smoothness under family governance

WILLINGNESS AND ABILITY TO PERFORM INFORMATION SECURITY COMPLIANCE BEHAVIOR: PSYCHOLOGICAL OWNERSHIP AND SELF-EFFICACY PERSPECTIVE

Information security policy effectiveness relies on how well an individual employee can follow the specified instruction described in security policies. The actual taking place of such compliance behavior is determined by individuals’ willingness and capability of performing such behavior. In this study, we used psychological ownership to represent the driver of willingness and self-efficacy to represent individuals’ capability belief. In addition to understanding the impacts of these two variables on compliance behavior, we also explore their antecedents. Data collected from 234 employees in organizations with specific security policies were used to examine the proposed hypotheses. We confirmed the positive impact of selfefficacy but, surprisingly, found the negative impact of psychological ownership. Such a result generates some interesting implications for researchers and practitioners

A Comparative Study on Spin-Orbit Torque Efficiencies from W/ferromagnetic and W/ferrimagnetic Heterostructures

It has been shown that W in its resistive form possesses the largest spin-Hall ratio among all heavy transition metals, which makes it a good candidate for generating efficient dampinglike spin-orbit torque (DL-SOT) acting upon adjacent ferromagnetic or ferrimagnetic (FM) layer. Here we provide a systematic study on the spin transport properties of W/FM magnetic heterostructures with the FM layer being ferromagnetic Co$_{20}$Fe$_{60}$B$_{20}$ or ferrimagnetic Co$_{63}$Tb$_{37}$ with perpendicular magnetic anisotropy. The DL-SOT efficiency $|\xi_{DL}|$, which is characterized by a current-induced hysteresis loop shift method, is found to be correlated to the microstructure of W buffer layer in both W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ systems. Maximum values of $|\xi_{DL}|\approx 0.144$ and $|\xi_{DL}|\approx 0.116$ are achieved when the W layer is partially amorphous in the W/Co$_{20}$Fe$_{60}$B$_{20}$ and W/Co$_{63}$Tb$_{37}$ heterostructures, respectively. Our results suggest that the spin Hall effect from resistive phase of W can be utilized to effectively control both ferromagnetic and ferrimagnetic layers through a DL-SOT mechanism

Controlled Heterogeneous Nucleation and Growth of Germanium Quantum Dots on Nanopatterned Silicon Dioxide and Silicon Nitride Substrates

Controlled heterogeneous nucleation and growth of Ge quantum dots (QDs) are demonstrated on SiO_2/Si_3N_4 substrates by means of a novel fabrication process of thermally oxidizing nanopatterned SiGe layers. The otherwise random self-assembly process for QDs is shown to be strongly influenced by the nanopatterning in determining both the location and size of the QDs. Ostwald ripening processes are observed under further annealing at the oxidation temperature. Both nanopattern oxidation and Ostwald ripening offer additional mechanisms for lithography for controlling the size and placement of the QDs