The impact of regulation on market quality

This dissertation studies the impact of market structure changes on market efficiency and integrity. Thematically, it is concerned with the actual behaviour of market participants and their associated impact on key market variables such as the degree of liquidity, the size of trading costs, the quality of price discovery and the integrity of the market itself. The fundamental changes to the trading landscape brought about by fragmentation have significantly changed the way that many traders execute transactions. In light of the vast and complex changes that have recently occurred in markets, this thesis conducts an empirical investigation of these microstructure issues. These studies contribute to the understanding of modern markets, the health of which is integral for effective price discovery and liquidity provision. The four studies in this dissertation examine several key market microstructure issues, including: causes of the pre-bid price run-up ahead of takeover announcements; the impact high frequency trading has on market efficiency and integrity; and the effect of both the introduction and regulation of dark trading. The outcomes of these studies are comprehensively discussed and their contributions to the field are duly noted. Given the significant and rapid change occurring in current equity markets, the findings in this dissertation are relevant for market practitioners, exchange venue designers, and market regulators

The impact of regulation on market quality

This dissertation studies the impact of market structure changes on market efficiency and integrity. Thematically, it is concerned with the actual behaviour of market participants and their associated impact on key market variables such as the degree of liquidity, the size of trading costs, the quality of price discovery and the integrity of the market itself. The fundamental changes to the trading landscape brought about by fragmentation have significantly changed the way that many traders execute transactions. In light of the vast and complex changes that have recently occurred in markets, this thesis conducts an empirical investigation of these microstructure issues. These studies contribute to the understanding of modern markets, the health of which is integral for effective price discovery and liquidity provision. The four studies in this dissertation examine several key market microstructure issues, including: causes of the pre-bid price run-up ahead of takeover announcements; the impact high frequency trading has on market efficiency and integrity; and the effect of both the introduction and regulation of dark trading. The outcomes of these studies are comprehensively discussed and their contributions to the field are duly noted. Given the significant and rapid change occurring in current equity markets, the findings in this dissertation are relevant for market practitioners, exchange venue designers, and market regulators

Dust devils on Mars: Effects of surface roughness on particle threshold

Abstract not available

On the Progenitor System of the Type Iax Supernova 2014dt in M61

We present pre-explosion and post-explosion Hubble Space Telescope images of the Type Iax supernova (SN Iax) 2014dt in M61. After astrometrically aligning these images, we do not detect any stellar sources at the position of the SN in the pre-explosion images to relatively deep limits (3 sigma limits of M_F438W > -5.0 mag and M_F814W > -5.9 mag). These limits are similar to the luminosity of SN 2012Z's progenitor system (M_F435W = -5.43 +/- 0.15 and M_F814W = -5.24 +/- 0.16 mag), the only probable detected progenitor system in pre-explosion images of a SN Iax, and indeed, of any white dwarf supernova. SN 2014dt is consistent with having a C/O white-dwarf primary/helium-star companion progenitor system, as was suggested for SN 2012Z, although perhaps with a slightly smaller or hotter donor. The data are also consistent with SN 2014dt having a low-mass red giant or main-sequence star companion. The data rule out main-sequence stars with M_init > 16 M_sun and most evolved stars with M_init > 8 M_sun as being the progenitor of SN 2014dt. Hot Wolf-Rayet stars are also allowed, but the lack of nearby bright sources makes this scenario unlikely. Because of its proximity (D = 12 Mpc), SN 2014dt is ideal for long-term monitoring, where images in ~2 years may detect the companion star or the luminous bound remnant of the progenitor white dwarf.Comment: 5 pages, 3 figures, submitted to ApJ

Dust Formation and He II 4686 emission in the Dense Shell of the Peculiar Type Ib Supernova 2006jc

We present evidence for the formation of dust grains in an unusual Type Ib SN based on late-time spectra of SN 2006jc. The progenitor suffered an LBV-like outburst just 2 yr earlier, and we propose that the dust formation is a consequence of the SN blast wave overtaking that LBV-like shell. The key evidence for dust formation is (a) the appearance of a red/near-IR continuum source fit by 1600 K graphite grains, and (b) fading of the redshifted sides of He I emission lines, yielding progressively more asymmetric blueshifted lines as dust obscures receding material. This provides the strongest case yet for dust formation in any SN Ib/c. Both developments occurred between 51 and 75 d after peak, while other SNe observed to form dust did so after a few hundred days. Geometric considerations indicate that dust formed in the dense swept-up shell between the forward and reverse shocks, and not in the freely expanding SN ejecta. Rapid cooling leading to dust formation may have been aided by extremely high shell densities, as indicated by He I line ratios. The brief epoch of dust formation is accompanied by He II 4686 emission and enhanced X-ray emission. These clues suggest that the unusual dust formation in this object was not due to properties of the SN itself, but instead -- like most peculiarities of SN 2006jc -- was a consequence of the dense environment created by an LBV-like eruption 2 yr before the SN.Comment: ApJ, accepted. added some discussion and 2 figures, better title, conclusions same as previous version. 12 pages, 4 color fig

Sleep analysis for elderly care using a low-resolution visual sensor network

Nearly half of the senior citizens report difficulty initiating and maintaining sleep. Frequent visits to the bathroom in the middle of the night is considered as one of the major reasons for sleep disorder. This leads to serious diseases such as depression and diabetes. In this paper, we propose to use a network of cheap low-resolution visual sensors (30 x 30 pixels) for long-term activity analysis of a senior citizen in a service flat. The main focus of our research is on elderly behaviour analysis to detect health deterioration. Specifically, this paper treats the analysis of sleep patterns. Firstly, motion patterns are detected. Then, a rule-based approach on the motion patterns is proposed to determine the wake up time and sleep time. The nightly bathroom visit is identified using a classification-based model. In our evaluation, we performed experiments on 10 months of real-life data. The ground truth is collected from the diaries in which the senior citizen wrote down his sleep time and wake up time. The results show accurate extraction of the sleep durations with an overall Mean Absolute Error (MAE) of 22.91 min and Spearman correlation coefficient of 0.69. Finally, the nightly bathroom visits analysis indicate sleep disorder in several nights

Variational guidewire tracking using phase congruency

We present a novel method to track a guidewire in cardiac x-ray video. Using variational calculus, we derive differential equations that deform a spline, subject to intrinsic and extrinsic forces, so that it matches the image data, remains smooth, and preserves an a priori length. We analytically derive these equations from first principles, and show how they include tangential terms, which we include in our model. To address the poor contrast often observed in x-ray video, we propose using phase congruency as an image-based feature. Experimental results demonstrate the success of the method in tracking guidewires in low contrast x-ray video