Convergence rate to a lower tail dependence coefficient of a skew-t distribution

We examine the rate of decay to the limit of the tail dependence coefficient of a bivariate skew t distribution which always displays asymptotic tail dependence. It contains as a special case the usual bivariate symmetric t distribution, and hence is an appropriate (skew) extension. The rate is asymptotically power-law. The second-order structure of the univariate quantile function for such a skew-t distribution is a central issue.Comment: 14 page

Timing for hippocampal synaptic plasticity

The timing of a spike with afferent excitation has been proposed to influence the direction of synaptic plasticity. I hypothesize that positive excitation-spike (ES)- Pairing— generating a synaptic excitation before a spike— results in long-term potentiation (LTP), while the opposite (negative ES-Pairing) results in long-term depression (LTD) in vivo. Extracellular potentials were recorded in the hippocampal CA1 region in urethane-anesthetized rats. Basal dendritic excitation was evoked by subthreshold stratum oriens stimulation while stratum radiatum stimulation evoked a spike that invaded the basal dendrites. ES-Pairing (50 times at 5 Hz) at -10, 0 and +10, +20 ES Intervals resulted in a significant potentiation of the slope of the basal excitatory sink for 2 hr compared to controls. Pairing at -20 ms ES Interval did not result in significant potentiation compared to controls. Thus, dendritic excitation occurring within a short time window of a spike results in LTP in vivo

Prophylactic use of OKT3 in liver transplantation

Liver rejection in the era of cyclosporine-based immunosuppression is approximately 60–70%. Approximately 15–25% of liver transplant patients will require hemodialysis following transplantation. These facts argue for a potent, less nephrotoxic immunosuppressive regimen, especially during the period of vulnerability to these events. Prophylactic use of OKT3 has been suggested as a means to decrease the need for hemodialysis while maintaining potent immunosuppression. The goal of this review is to examine potential benefits and pitfalls of this regimen. A lack of documentation of long-term patient and graft survival, the potential susceptibility to infectious complications, development of sensitization, and the cost must be weighed against the decreased need for hemodialysis and the control of early rejection episodes

Locally Advanced Spiroadenocarcinoma in the Regional Axilla of a Breast Cancer Patient: Hallmarks of Definitive Diagnosis and Management.

Eccrine spiroadenocarcinoma is an extremely rare malignant eccrine gland tumor which may masquerade as other more common malignancies such as poorly differentiated squamous carcinoma or metastatic breast cancer. We report a case of an ulcerated axillary skin lesion with bulky adenopathy in a 77 year-old female with a prior history of ipsilateral triple negative breast carcinoma. The clear transition of benign spiradenoma to malignant carcinoma was essential to establishing a definitive diagnosis and treatment plan

Secrets of Success 成功之道

The senior managers of two of Hong Kong\u27s most prestigious private members\u27 clubs share their insights on how to build a thriving career in this unique environment. 香港兩家最享負盛名之私人會所的高級管理人員，分享他們在這獨特的環境下，如何成就璀璨事業

Defining Interactions Between Lymphoid Tissue-Resident Commensal Bacteria and the Host Immune System

The mammalian gastro-intestinal tract is colonized by trillions of beneficial commensal bacteria that are essential for promoting normal host physiology. While the majority of commensal bacteria are found in the intestinal lumen, many species have also adapted to colonize different anatomical locations in the intestine including the surface of intestinal epithelial cells (IECs) and the interior of gut-associated lymphoid tissues. Distinct tissue localization of commensal bacteria permits unique interactions between these microbes and the mammalian immune system and collectively influences intestinal immune cell homeostasis. Conversely, dysregulated localization of commensal bacteria can lead to inappropriate activation of the immune system and is associated with numerous chronic infectious, inflammatory and metabolic diseases. Therefore, regulatory mechanisms that control proper anatomical containment of commensal bacteria are essential to maintain tissue homeostasis and limit pathology. Although the roles of luminal and epithelial-associated commensal bacteria on immune cell homeostasis have been extensively studied, how lymphoid tissue-resident commensals (LRC) modulate host immune responses is not well understood. Data in Chapter 2 will describe interactions between a genetically related family of LRCs that can colonize dendritic cells and induces lymphoid tissue-specific immune responses. Further, Chapter 3 will provide evidence that LRC-induced immune responses are mutually beneficial for itself and the host. Specifically, LRC-induced interleukin (IL)-22 enhances its own microbial colonization and LRC-induced IL-10 limits tissue inflammation during intestinal injury. Dysregulated anatomical localization of commensal bacteria during chronic inflammatory conditions is typically associated with extra-intestinal complications including anemia or dysregulated iron homeostasis. Results in Chapter 4 support a role for the iron-regulatory hormone hepcidin in modulating LRC colonization of DCs and identify hepcidin as a critical regulator of immune cell homeostasis and tissue repair following intestinal injury. Collectively, studies presented in this thesis define mutually beneficial interactions between mammalian hosts and commensal bacteria in intestinal-associated lymphoid tissues that regulate immune cell homeostasis and host responses to tissue inflammation or injury

Tail asymptotics for the bivariate skew normal in the general case

The present paper is a sequel to and generalization of Fung and Seneta (2016) whose main result gives the asymptotic behaviour as $u \to 0^{+}$ of $\lambda_L(u) = P(X_1 \leq F_1^{-1}(u) | X_2 \leq F_2^{-1}(u)),$ when $\bf{X} \sim SN_2(\boldsymbol{\alpha}, R)$ with $\alpha_1 = \alpha_2 = \alpha,$ that is: for the bivariate skew normal distribution in the equi-skew case, where $R$ is the correlation matrix, with off-diagonal entries $\rho,$ and $F_i(x), i=1,2$ are the marginal cdf's of $\textbf{X}$. A paper of Beranger et al. (2017) enunciates an upper-tail version which does not contain the constraint $\alpha_1=\alpha_2= \alpha$ but requires the constraint $0 <\rho <1$ in particular. The proof, in their Appendix A.3, is very condensed. When translated to the lower tail setting of Fung and Seneta (2016), we find that when $\alpha_1=\alpha_2= \alpha$ the exponents of $u$ in the regularly varying function asymptotic expressions do agree, but the slowly varying components, always of asymptotic form $const (-\log u)^{\tau}$, are not asymptotically equivalent. Our general approach encompasses the case $-1 <\rho < 0$, and covers all possibilities.Comment: 82 page