Domain Knowledge Infusion in Machine Learning for Digital Signal Processing Applications : An in-depth case study on table tennis stroke recognition

Diese Arbeit untersucht die Infusion von Domänenwissen als eine Möglichkeit zur Optimierung von Anwendungen des maschinellen Lernens in der Signalverarbeitung. Als Anwendungsbeispiel wird die Erkennung von Tischtennisschlägen anhand von Signalen detailliert analysiert. Die Signale stammen von Sensoren, die in einer am Handgelenk getragenen Smartwatch integriert sind. Domänenwissen wird auf verschiedenen Abstraktionsebenen verwendet, um die Schlagerkennung und -klassifikation zu verbessern. Diese reichen von der Wahl und Fusion tischtennisrelevanter Sensoren, über Low-Level-Signalkorrekturen, bis hin zu Zustandsautomaten, die basierend auf dem Wissen über gültige Schlagsequenzen eine Selbstkorrektur von Fehlklassifikationen ermöglichen. Die Evaluation des LSTMbasierten Prototyps zeigt, dass er erfolgreich zwischen Spiel/kein Spiel, Schlag/kein Schlag, und acht Schlagarten (Vorhand/Rückhand Konter, Topspin, Block, Unterschnitt) unterscheiden kann, sowie Metriken zukünftiger Schläge zur Analyse des Spielstils basierend auf vergangenen Schlägen vorhersagen kann. Das System wurde basierend auf 3770 Schlägen von zwei langjährigen Tischtennisspielern entwickelt und validiert. Die Daten wurden in einer kontrollierten Umgebung unter Zuhilfenahme eines Tischtennisroboters gesammelt, der Bälle präzise servieren kann

Transform-limited single photons from a single quantum dot

A semiconductor quantum dot mimics a two-level atom. Performance as a single photon source is limited by decoherence and dephasing of the optical transition. Even with high quality material at low temperature, the optical linewidths are a factor of two larger than the transform-limit. A major contributor to the inhomogeneous linewdith is the nuclear spin noise. We show here that the nuclear spin noise depends on optical excitation, increasing (decreasing) with increasing resonant laser power for the neutral (charged) exciton. Based on this observation, we discover regimes where we demonstrate transform-limited linewidths on both neutral and charged excitons even when the measurement is performed very slowly

Evaluation of the mirn23a Cluster through an iTRAQ-based Quantitative Proteomic Approach

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that are implicated in a number of disease states. MiRNAs can exist as individual entities, or may be clustered and transcribed as a single polycistron. The mirn23a cluster consists of three miRNAs, miR-23a, miR-24-2, and miR-27a. While these miRNAs are transcribed together, they often exist at varying levels in the cell. Despite the fact that the mirn23a cluster is known to play a role in a number of diseases and developmental processes, few direct targets have been identified. In this study, we examined the effects of miR-23a, miR-24-2, miR-27a, or the mirn23a cluster overexpression on the proteome of 70Z/3 pre-B lymphoblast cells. Quantitative mass spectrometry using isobaric tags for relative and absolute quantification (iTRAQ) allowed for global profiling of cell lines after miRNA overexpression. We identified a number of targets of each miRNA that contained predicted miRNA seed sequences and are likely direct targets. In addition, we discovered a cohort of shared miRNA targets and cluster targets, demonstrating the importance of studying miRNA clusters in their entirety

Epitaxial lift-off for solid-state cavity quantum electrodynamics

We present a new approach to incorporate self-assembled quantum dots into a Fabry-P\'{e}rot-like microcavity. Thereby a 3$\lambda$/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4,100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor - mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggests that we are close to the strong coupling regime.Comment: 6 pages, 4 figure

Electrically-tunable hole g-factor of an optically-active quantum dot for fast spin rotations

We report a large g-factor tunability of a single hole spin in an InGaAs quantum dot via an electric field. The magnetic field lies in the in-plane direction x, the direction required for a coherent hole spin. The electrical field lies along the growth direction z and is changed over a large range, 100 kV/cm. Both electron and hole g-factors are determined by high resolution laser spectroscopy with resonance fluorescence detection. This, along with the low electrical-noise environment, gives very high quality experimental results. The hole g-factor g_xh depends linearly on the electric field Fz, dg_xh/dFz = (8.3 +/- 1.2)* 10^-4 cm/kV, whereas the electron g-factor g_xe is independent of electric field, dg_xe/dFz = (0.1 +/- 0.3)* 10^-4 cm/kV (results averaged over a number of quantum dots). The dependence of g_xh on Fz is well reproduced by a 4x4 k.p model demonstrating that the electric field sensitivity arises from a combination of soft hole confining potential, an In concentration gradient and a strong dependence of material parameters on In concentration. The electric field sensitivity of the hole spin can be exploited for electrically-driven hole spin rotations via the g-tensor modulation technique and based on these results, a hole spin coupling as large as ~ 1 GHz is expected to be envisaged.Comment: 8 pages, 4 figure

Coherent and robust high-fidelity generation of a biexciton in a quantum dot by rapid adiabatic passage

A biexciton in a semiconductor quantum dot is a source of polarization-entangled photons with high potential for implementation in scalable systems. Several approaches for non-resonant, resonant and quasi-resonant biexciton preparation exist, but all have their own disadvantages, for instance low fidelity, timing jitter, incoherence or sensitivity to experimental parameters. We demonstrate a coherent and robust technique to generate a biexciton in an InGaAs quantum dot with a fidelity close to one. The main concept is the application of rapid adiabatic passage to the ground state-exciton-biexciton system. We reinforce our experimental results with simulations which include a microscopic coupling to phonons.Comment: Main manuscript 5 pages and 4 figures, Supplementary Information 5 pages and 3 figures, accepted as a Rapid Communication in PRB. arXiv admin note: text overlap with arXiv:1701.0130

The determinants of urban household poverty in Malaysia

Since independence in 1950s Malaysia has been recognised as one of the more successful countries in fighting poverty: head count ratio came down to 5.7 percent by 2004. However the recent process of rapid urbanization has led to an increase of urban poverty aggravated further by the 1997 Asian financial crisis. It is important to understand the nature and scale of urbanization, the various driving forces that affect it and the determinants of urban poverty as linked to this process. Our paper identifies the determinants of urban poverty in Malaysia using a logistic regression. Multiple regression model which used to be the main tool of analysis in this kind of studies has been criticised for a number of drawbacks and binary probit or logit models have been proposed as alternative and widely used. Previous studies have used income to identify poor households. We have two problems with this procedure. First, the official poverty line in Malaysia is an consumption expenditure. Secondly data on household incomes are known to be less reliable than consumption data obtained from household expenditure surveys. We therefore compare a person’s consumption expenditure with the poverty line to determine its poverty status. This agrees with the idea that poverty is the inability to attain a critical minimum amount of consumption. We study the effect of human capital, region of residence and other household characteristics on urban poverty using this benchmark A sample of 2,403 urban households from the 2004-05 Household Expenditure Survey (HES) has been used in this research. We first estimate the probability of households with specified characteristics to fall below Malaysia’s official poverty line. Results show that human capital significantly reduces the chance of being poor while migrant workers are more prone to poverty. Household size, race and regions are also important determinants of poverty outcome in urban Malaysia. Then we analyse the sensitivity of the probability estimates to shift of the poverty line over a reasonable range. Effects of education, number of children, number of male adults, number of elderly, foreign migrant-headed household, Chinese household and households living in Region 1 on poverty are robust over the shifts. The findings have important policy implications for Malaysian government which has pledged to reduce overall poverty rate to 2.8 percent and eradicate hardcore poverty by 2010 under the Ninth Malaysian Plan