A recursive online algorithm for the estimation of time-varying ARCH parameters

In this paper we propose a recursive online algorithm for estimating the parameters of a time-varying ARCH process. The estimation is done by updating the estimator at time point $t-1$ with observations about the time point $t$ to yield an estimator of the parameter at time point $t$. The sampling properties of this estimator are studied in a non-stationary context -- in particular, asymptotic normality and an expression for the bias due to non-stationarity are established. By running two recursive online algorithms in parallel with different step sizes and taking a linear combination of the estimators, the rate of convergence can be improved for parameter curves from H\"{o}lder classes of order between 1 and 2.Comment: Published at http://dx.doi.org/10.3150/07-BEJ5009 in the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

The quantile spectral density and comparison based tests for nonlinear time series

In this paper we consider tests for nonlinear time series, which are motivated by the notion of serial dependence. The proposed tests are based on comparisons with the quantile spectral density, which can be considered as a quantile version of the usual spectral density function. The quantile spectral density 'measures' sequential dependence structure of a time series, and is well defined under relatively weak mixing conditions. We propose an estimator for the quantile spectral density and derive its asympototic sampling properties. We use the quantile spectral density to construct a goodness of fit test for time series and explain how this test can also be used for comparing the sequential dependence structure of two time series. The method is illustrated with simulations and some real data examples

Statistical inference for time-varying ARCH processes

In this paper the class of ARCH$(\infty)$ models is generalized to the nonstationary class of ARCH$(\infty)$ models with time-varying coefficients. For fixed time points, a stationary approximation is given leading to the notation ``locally stationary ARCH$(\infty)$ process.'' The asymptotic properties of weighted quasi-likelihood estimators of time-varying ARCH$(p)$ processes ($p<\infty$) are studied, including asymptotic normality. In particular, the extra bias due to nonstationarity of the process is investigated. Moreover, a Taylor expansion of the nonstationary ARCH process in terms of stationary processes is given and it is proved that the time-varying ARCH process can be written as a time-varying Volterra series.Comment: Published at http://dx.doi.org/10.1214/009053606000000227 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Changing librarianship in the collaborative era: a case study from New Zealand

Purpose: To consider changing roles of academic librarians in particular the role of subject liaison librarians in the 21 st century education. The aim is to stimulate debate on changing roles of librarians, to suggest possibilities and encourage others to envisage librarians and the change process in multiple ways. Design/methodology/approach: Self-review to the researcher is a process through which library roles and services evaluate the effectiveness of what they do, with the aim of improving the quality of their library practice. “Self-review as a form of ‘practical philosophy’ whereby the philosophical values that underpin the practice of both the individuals and the teaching team as a collective, are examined through a process of reflection and dialogue” (Grey, 2010). Findings: The researcher does not wish to form any fixed generalisations about librarians’ roles, instead seek to problematize and discuss an approach that was completed in a context to make visible the understandings and interpretations of those immediately involved in the process. Practical Implications: It is presumed to be significant as the article is a form of self-review; based on the philosophical and values of those directly involved in the service, and so reviews the implementation of philosophy, rather than measuring behaviour against a set of externally defined criteria. Originality/value: This approach contends that evaluation of self- review should consist of a process of meaning making, rather than just the assessment of practice, whereby external behaviour is modified by first examining the underlying values on which it is based

The Phosphoinositide 3-Kinase Isoform PI3Kβ Regulates Osteoclast-Mediated Bone Resorption in Humans and Mice

OBJECTIVE: While phosphoinositide 3-kinases (PI3Ks) are involved in various intracellular signal transduction processes, the specific functions of the different PI3K isoforms are poorly understood. We have previously shown that the PI3Kβ isoform is required for arthritis development in the K/BxN serum–transfer model. Since osteoclasts play a critical role in pathologic bone loss during inflammatory arthritis and other diseases, we undertook this study to test the role of PI3Kβ in osteoclast development and function using a combined genetic and pharmacologic approach. METHODS: The role of PI3Kβ in primary human and murine osteoclast cultures was tested with the PI3Kβ-selective inhibitor TGX221 and by using PI3Kβ(−/−) mice. The trabecular bone architecture of PI3Kβ(−/−) mice was evaluated using micro–computed tomography and histomorphometric analyses. RESULTS: The expression of PI3Kβ was strongly and specifically up-regulated during in vitro osteoclast differentiation. In vitro development of large multinucleated osteoclasts from human or murine progenitors and their resorption capacity were strongly reduced by the PI3Kβ inhibitor TGX221 or by the genetic deficiency of PI3Kβ. This was likely due to defective cytoskeletal reorganization and vesicular trafficking, since PI3Kβ(−/−) mouse multinucleated cells failed to form actin rings and retained intracellular acidic vesicles and cathepsin K. In contrast, osteoclast-specific gene expression and the survival and apoptosis of osteoclasts were not affected. PI3Kβ(−/−) mice had significantly increased trabecular bone volume and showed abnormal osteoclast morphology with defective resorption pit formation. CONCLUSION: PI3Kβ plays an important role in osteoclast development and function and is required for in vivo bone homeostasis

Novel Regulatory Mechanisms and Functions of MUC4 in Pancreatic Cancer

Mucins are high molecular weight glycoproteins and have critical functions in protecting epithelial cells from a myriad of cellular stress. However, mucins are expressed aberrantly under cancer conditions that allow tumors to progress and metastasize. Among many mucins, Mucin 4 (MUC4) serves as one of the top-differentially expressed proteins in pancreatic cancer (PC), however, the precise mechanism responsible for its aberrant expression is still not clear. The evolving view of cancer as an energetic and growing ecosystem underlines an intricate interplay between cancer and its microenvironment. In spite of being recognized as one of the most critical oncogenic proteins in PC, MUC4 regulation in terms of micro-environmental stress has not been determined. In my dissertation research, I have investigated the role of PC microenvironment in the regulation of MUC4. From my studies, I have demonstrated that MUC4 stability is significantly reduced due to hypoxia-mediated induction of reactive oxygen species (ROS), which promotes autophagy by inhibiting pAkt/mTORC1 pathway. Hypoxia-mediated degradation of MUC4 provides necessary metabolites to ensure the survival of highly stressed PC cells. The longstanding model of cancer development involves that presence of cytokines can trigger chronic inflammation and impact tumor development, including PC. In addition to cytokines, bile acids (BA) facilitated chronic inflammation has shown to induce intestinal metaplasia, but their role in PC is still elusive. Elevated levels of BA (p In addition to the regulation, I have pinpointed the novel functional roles of MUC4 in determining the fate of receptor tyrosine kinases (RTKs) in PC. Multiple studies have associated MUC4 overexpression with increased stability of RTKs for sustained proliferation; however, no studies have so far highlighted the implicated mechanism. I have demonstrated that the presence of MUC4 leads to increased internalization and recycling of EGFR and HER2 to the plasma membrane compared to MUC4 silenced PC cells. Mechanistically, the impact of MUC4 on RTKs trafficking is associated with its ability to regulate the activity of RAB5A, which is known to catalyze the rate-limiting step in receptor internalization. Lastly, I have detected the presence of MUC4 in pancreatic cancer associated stellate cells (PaSC). This was an unexpected finding given that MUC4 is normally expressed in the epithelial cells. These results indicate towards the involvement of MUC4 expression in determining the activation status of PaSC and provide us an additional strong rationale to therapeutically target MUC4. Altogether, in my dissertation research, I have elucidated the novel regulatory mechanisms and functions of MUC4 in PC condition

Mainstreaming Mentally Retarded Children Through Inclusive Education Under SSA - A Case Study

‘Sarva  Shiksha  Abhiyan’ is a national govt. scheme for primary education. Under this scheme, all physically & mentally challenged students of age gr. 6-14 were brought under inclusive education section.  Access and retention in school was challenge for MR student. Parents were not ready to send them in school as it was meaningless for the children. But, schooling not only retained but developed them optimally through formal education and connected with society. A case study of girl child is presented here

Ocular Manifestations of Blood Dyscrasias

The ocular manifestations of blood dyscrasias are distinctive and are attributed to high vascularity and to the unique anatomy of the eye. They may be the initial finding of the underlying pathology or discovered during the course of the disease. This study is undertaken to describe the incidence and various types of manifestations seen in blood dyscrasias and to assess the diagnostic and prognostic importance as well as the resolution of lesions with treatment. This study was done on 100 patients of various age groups with different types of hematological disorders over a period of two years from Nov 2015 to Aug 2016 in the Department of Ophthalmology, Govt. Stanley Hospital. Of 100 patients, 63 patients had hematological malignancies, Non-Hodgkin Lymphomas being the single largest group, 34 patients with anemia and 3 patients had bleeding disorders.31 patients presented primarily to the ophthalmologist with defective vision as the most common symptom and following evaluation were diagnosed to have blood dyscrasias, thus emphasising the need for thorough ocular screening. 41% patients examined for ocular findings showed retinopathy, most commonly in the form of retinal hemorrhages followed by cotton-wool spots. The lesions show resolution with treatment in 90% of cases in both malignant and non- malignant disorders. Thus ocular manifestations are a frequent occurrence in blood dyscrasias and should be evaluated with a high index of suspicion when found