A New Look at Copper Markets: A Regime-Switching Jump Model

GARCH-jump models of metal price returns, while allowing for sudden movements (jumps), apply the same specification of the jump component in both 'bear'and 'bull' markets. As a result, the more frequent but relatively small jumps that occur in both bear and bull markets dominate the characterization of the jump process. Given that large jumps, although less frequent, are still quite common in copper (and other metal) markets, this is a potential shortcoming of current models. More flexibility can be added to the modeling process by allowing for regime-switching. In this paper we specify a model that allows for switching across two separate regimes, with the possibility of different jump sizes and frequencies under each regime, along with a regime-specific GARCH process for the conditional variance. This model is applied to daily copper futures prices over the period of January 2 1980 through the end of July 2007. The model is estimated both with and without factors such as interest and exchange rate movements entering into the specification of the state-dependent mean of the conditional jump size. In some respects, a Regime Switching GARCH-Jump Model performs well when applied to the copper returns data. The results are mixed in terms of whether or not variations of the model that allow jump sizes to be a function of interest or exchange rates offer much of an advantage over a pure time series approach to the modeling of copper returns over the past three decades.regime switching; Poisson jump; GARCH volatility; copper futures

Otoscopic visualization of cerumen: inter-rater agreement

A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, June 30, 2005.Also available in print.Thesis (B.Sc)--University of Hong Kong, 2005.published_or_final_versionSpeech and Hearing SciencesBachelorBachelor of Science in Speech and Hearing Science

Peripheral and local immune responses in pregnancy and preterm birth

Preterm birth (PTB) affects 11% of pregnancies worldwide and the leading cause is infection and inflammation. The maternal immune system undergoes temporal adaptions during healthy pregnancy, but how this may be altered in PTB remains largely unexplored. The vaginal microbial composition influences pregnancy outcome, although the mechanism of microbial-driven PTB is not well understood. This thesis explores if there are peripheral and local immune signatures in women who undergo microbial-driven PTB. The key aims were to describe 1) changes in the maternal immune response in healthy pregnancy and spontaneous PTB, 2) alterations in the immune response to cervical shortening and cervical cerclage and 3) differences in the immune response to the vaginal microbial composition in term and preterm pregnancies. Temporal adaptations in the peripheral immune response were similar in term and preterm pregnancies and were not directly impacted by the vaginal microbiota. Activation of the local innate and adaptive immune response were seen in cervical shortening, and in a proportion of women who delivered preterm. Lactobacillus iners and diverse microbial composition were associated with increases in local mediators of microbial recognition, complement and pro-inflammatory cytokines. This response was augmented in those who delivered preterm, suggestive of a dysregulated immune response. In contrast, cervical shortening and PTB in the presence of Lactobacillus crispatus was not associated with activation of the innate or adaptive immune response, therefore were likely to be driven by alternative causes. Placement of a Mersilene cerclage led to an augmented immune response and was associated with higher PTB rates compared to Nylon, and therefore should not be used. Microbial-driven PTB involves microbial recognition and activation of the complement cascade, leading to a pro-inflammatory local immune milieu. This opens the door for the development of immune modulators, complement inhibitors and probiotics to mitigate the risk of microbial driven PTB.Open Acces

Neuroimaging in Paediatric Tuberous Sclerosis Complex

This thesis explores novel aspects of the neuroradiological features of tuberous sclerosis complex (TSC), including the relationship between these features and subsequent epilepsy and developmental outcome in later childhood. The neuroradiological features of TSC include cortical tubers, subependymal nodules and subependymal giant cell astrocytoma (SEGA). Patients with TSC have high rates of refractory epilepsy, developmental delay and Autism Spectrum Disorder (ASD), but are affected to varying degrees leading to a wide phenotypic spectrum. Prior studies focussing on TSC neuroradiological markers have found some associations between lesion burden and severity of neurological dysfunction, but the literature remains inconclusive. Literature regarding congenital SEGA is limited but suggested they grew more aggressively than other SEGA. The first study in this thesis addresses this literature gap through a case series of ten congenital SEGA at a single TSC referral centre. Using serial MRI, our study found median congenital SEGA growth rate of 1.1mm/yr in diameter or 150mm3/yr volumetrically, which is lower than previous reports. Congenital SEGA with volume >500mm3 had significantly higher growth rates compared with smaller SEGA. Children with congenital SEGA tended to have more severe epilepsy, developmental disability and ASD compared to genotype-matched controls, suggesting that congenital SEGA may be a biomarker for poor neurological outcome, which is a novel finding. The second study explores whether neuroradiological features of TSC on early MRI are biomarkers for neurological and developmental outcomes. Thirty-nine MRIs acquired between 18-36 months from children with TSC were scored blindly. We found children with drug resistant epilepsy (DRE) had more tubers and subependymal nodules (SEN) compared to children without DRE. More frontal tubers were found in children with impaired adaptive function and children with ASD. Therefore, tuber count and frontal tuber location on early MRI may contribute to predicting DRE, adaptive function and ASD at 5 years of age. In conclusion, this thesis determines that neuroradiological markers have an important role in understanding TSC patients’ neurological and developmental outcome at 5 years of age. Early identification of patients at risk for poor outcomes would open opportunities for early intervention and more aggressive epilepsy treatment with the aim of optimising neurological and developmental outcome

Thermische Alterung von Dieseloxidationskatalysatoren und NOx-Speicherkatalysatoren: Korrelierung von Aktivität und Speicherfähigkeit mit physikalischen und chemischen Katalysatoreigenschaften

Steigende Anforderungen an die Emissionslimitierung bei Kraftfahrzeugen erfordern ein simulationsgestützes Vorgehen bei der Entwicklung von Autoabgasnachbehandlungssystemen. Da die Aktivität der für die Abgasreinigung eingesetzten Katalysatoren über die Lebensdauer abnimmt, ist die Berücksichtigung des Alterungsverhaltens bei der Auslegung der Systeme unerlässlich. Das Ziel dieser Arbeit ist ein besseres Verständnis der thermischen Alterung von Dieseloxidations- und NOx-Speicherkatalysatoren

Differences in reactivation of tuberculosis induced from anti-tnf treatments are based on bioavailability in granulomatous tissue

The immune response to Mycobacterium tuberculosis (Mtb) infection is complex. Experimental evidence has revealed that tumor necrosis factor (TNF) plays a major role in host defense against Mtb in both active and latent phases of infection. TNF-neutralizing drugs used to treat inflammatory disorders have been reported to increase the risk of tuberculosis (TB), in accordance with animal studies. The present study takes a computational approach toward characterizing the role of TNF in protection against the tubercle bacillus in both active and latent infection. We extend our previous mathematical models to investigate the roles and production of soluble (sTNF) and transmembrane TNF (tmTNF). We analyze effects of anti-TNF therapy in virtual clinical trials (VCTs) by simulating two of the most commonly used therapies, anti-TNF antibody and TNF receptor fusion, predicting mechanisms that explain observed differences in TB reactivation rates. The major findings from this study are that bioavailability of TNF following anti-TNF therapy is the primary factor for causing reactivation of latent infection and that sTNF-even at very low levels-is essential for control of infection. Using a mathematical model, it is possible to distinguish mechanisms of action of the anti-TNF treatments and gain insights into the role of TNF in TB control and pathology. Our study suggests that a TNF-modulating agent could be developed that could balance the requirement for reduction of inflammation with the necessity to maintain resistance to infection and microbial diseases. Alternatively, the dose and timing of anti-TNF therapy could be modified. Anti-TNF therapy will likely lead to numerous incidents of primary TB if used in areas where exposure is likely. © 2007 Marino et al

Detection of doxorubicin-induced apoptosis of leukemic T-lymphocytes by laser tweezers Raman spectroscopy

Laser tweezers Raman spectroscopy (LTRS) was used to acquire the Raman spectra of leukemic T lymphocytes exposed to the chemotherapy drug doxorubicin at different time points over 72 hours. Changes observed in the Raman spectra were dependent on drug exposure time and concentration. The sequence of spectral changes includes an intensity increase in lipid Raman peaks, followed by an intensity increase in DNA Raman peaks, and finally changes in DNA and protein (phenylalanine) Raman vibrations. These Raman signatures are consistent with vesicle formation, cell membrane blebbing, chromatin condensation, and the cytoplasm of dead cells during the different stages of drug-induced apoptosis. These results suggest the potential of LTRS as a real-time single cell tool for monitoring apoptosis, evaluating the efficacy of chemotherapeutic treatments, or pharmaceutical testing