Multitask and transfer learning for multi-aspect data

Supervised learning aims to learn functional relationships between inputs and outputs. Multitask learning tackles supervised learning tasks by performing them simultaneously to exploit commonalities between them. In this thesis, we focus on the problem of eliminating negative transfer in order to achieve better performance in multitask learning. We start by considering a general scenario in which the relationship between tasks is unknown. We then narrow our analysis to the case where data are characterised by a combination of underlying aspects, e.g., a dataset of images of faces, where each face is determined by a person's facial structure, the emotion being expressed, and the lighting conditions. In machine learning there have been numerous efforts based on multilinear models to decouple these aspects but these have primarily used techniques from the field of unsupervised learning. In this thesis we take inspiration from these approaches and hypothesize that supervised learning methods can also benefit from exploiting these aspects. The contributions of this thesis are as follows: 1. A multitask learning and transfer learning method that avoids negative transfer when there is no prescribed information about the relationships between tasks. 2. A multitask learning approach that takes advantage of a lack of overlapping features between known groups of tasks associated with different aspects. 3. A framework which extends multitask learning using multilinear algebra, with the aim of learning tasks associated with a combination of elements from different aspects. 4. A novel convex relaxation approach that can be applied both to the suggested framework and more generally to any tensor recovery problem. Through theoretical validation and experiments on both synthetic and real-world datasets, we show that the proposed approaches allow fast and reliable inferences. Furthermore, when performing learning tasks on an aspect of interest, accounting for secondary aspects leads to significantly more accurate results than using traditional approaches

Recent publications from the Alzheimer's Disease Neuroimaging Initiative: Reviewing progress toward improved AD clinical trials

INTRODUCTION: The Alzheimer's Disease Neuroimaging Initiative (ADNI) has continued development and standardization of methodologies for biomarkers and has provided an increased depth and breadth of data available to qualified researchers. This review summarizes the over 400 publications using ADNI data during 2014 and 2015. METHODS: We used standard searches to find publications using ADNI data. RESULTS: (1) Structural and functional changes, including subtle changes to hippocampal shape and texture, atrophy in areas outside of hippocampus, and disruption to functional networks, are detectable in presymptomatic subjects before hippocampal atrophy; (2) In subjects with abnormal β-amyloid deposition (Aβ+), biomarkers become abnormal in the order predicted by the amyloid cascade hypothesis; (3) Cognitive decline is more closely linked to tau than Aβ deposition; (4) Cerebrovascular risk factors may interact with Aβ to increase white-matter (WM) abnormalities which may accelerate Alzheimer's disease (AD) progression in conjunction with tau abnormalities; (5) Different patterns of atrophy are associated with impairment of memory and executive function and may underlie psychiatric symptoms; (6) Structural, functional, and metabolic network connectivities are disrupted as AD progresses. Models of prion-like spreading of Aβ pathology along WM tracts predict known patterns of cortical Aβ deposition and declines in glucose metabolism; (7) New AD risk and protective gene loci have been identified using biologically informed approaches; (8) Cognitively normal and mild cognitive impairment (MCI) subjects are heterogeneous and include groups typified not only by "classic" AD pathology but also by normal biomarkers, accelerated decline, and suspected non-Alzheimer's pathology; (9) Selection of subjects at risk of imminent decline on the basis of one or more pathologies improves the power of clinical trials; (10) Sensitivity of cognitive outcome measures to early changes in cognition has been improved and surrogate outcome measures using longitudinal structural magnetic resonance imaging may further reduce clinical trial cost and duration; (11) Advances in machine learning techniques such as neural networks have improved diagnostic and prognostic accuracy especially in challenges involving MCI subjects; and (12) Network connectivity measures and genetic variants show promise in multimodal classification and some classifiers using single modalities are rivaling multimodal classifiers. DISCUSSION: Taken together, these studies fundamentally deepen our understanding of AD progression and its underlying genetic basis, which in turn informs and improves clinical trial desig

Vision as inverse graphics for detailed scene understanding

An image of a scene can be described by the shape, pose and appearance of the objects within it, as well as the illumination, and the camera that captured it. A fundamental goal in computer vision is to recover such descriptions from an image. Such representations can be useful for tasks such as autonomous robotic interaction with an environment, but obtaining them can be very challenging due the large variability of objects present in natural scenes. A long-standing approach in computer vision is to use generative models of images in order to infer the descriptions that generated the image. These methods are referred to as “vision as inverse graphics” or “inverse graphics”. We propose using this approach to scene understanding by making use of a generative model (GM) in the form of a graphics renderer. Since searching over scene factors to obtain the best match for an image is very inefficient, we make use of convolutional neural networks, which we refer to as the recognition models (RM), trained on synthetic data to initialize the search. First we address the effect that occlusions on objects have on the performance of predictive models of images. We propose an inverse graphics approach to predicting the shape, pose, appearance and illumination with a GM which includes an outlier model to account for occlusions. We study how the inferences are affected by the degree of occlusion of the foreground object, and show that a robust GM which includes an outlier model to account for occlusions works significantly better than a non-robust model. We then characterize the performance of the RM and the gains that can be made by refining the search using the robust GM, using a new synthetic dataset that includes background clutter and occlusions. We find that pose and shape are predicted very well by the RM, but appearance and especially illumination less so. However, accuracy on these latter two factors can be clearly improved with the generative model. Next we apply our inverse graphics approach to scenes with multiple objects. We propose using a method to efficiently and differentiably model self shadowing which improves the realism of the GM renders. We also propose a way to render object occlusion boundaries which results in more accurate gradients of the rendering function. We evaluate these improvements using a dataset with multiple objects and show that the refinement step of the GM clearly improves on the predictions of the RM for the latent variables of shape, pose, appearance and illumination. Finally we tackle the task of learning generative models of 3D objects from a collection of meshes. We present a latent variable architecture that learns to separately capture the underlying factors of shape and appearance from the meshes. To do so we first transform the meshes of a given class to a data representation that sidesteps the need for landmark correspondences across meshes when learning the GM. The ability and usefulness of learning a disentangled latent representation of objects is demonstrated via an experiment where the appearance of one object is transferred onto the shape of another

The Effects of Second-language Repeated Reading on Reading Comprehension and Incidental Vocabulary Acquisition

Reading in a second language (L2) is considered a necessary skill in increasingly globalized societies. Not only is reading for purposes of comprehension necessary for survival, also reading in an L2 is an important means by which L2 acquisition occurs, particularly where vocabulary is concerned. Consequently, there is a strong demand for L2 research to investigate the instructional conditions that will best promote reading comprehension and vocabulary through efficient and effective reading strategies. The current study addressed this dual need, reading comprehension and vocabulary acquisition, through an investigation of a particular type of pedagogical intervention, repeated reading (RR; i.e., multiple encounters with the same text), with high school English language learners in Taiwan. The study examined the effects of three conditions – Unassisted RR (repeated reading only), Assisted RR (repeated reading plus listening), and Control – on the participants’ reading comprehension and incidental vocabulary acquisition through a pre-test, post-test, and delayed post-test design. The results of the data from 42 participants suggested that L2 RR did not promote reading comprehension, nor did it contribute to a transfer of practice effect to new text in terms of reading comprehension. However, there were statistically significant incidental vocabulary gains and retention for the Unassisted RR group and some vocabulary gains for the Assisted RR group. When the percentage of unknown words of a text reached 10% and the participants were not provided with additional support, five repeated encounters with the text (over eight treatment sessions) were found to be inadequate in promoting reading comprehension. Nonetheless, the participants provided with such challenging condition still benefited from the incidental vocabulary acquisition. Findings may imply that a certain threshold of proficiency (e.g., percentage of known words of a text) is necessary for the beneficial effects of repeated reading to support comprehension. Additionally, RR alone may still be insufficient and additional support to RR may still be necessary for L2 learners dealing with difficult texts

The transfer of safety training: unveiling the role of OHS trainers

The main goal of this thesis is to provide a contribution to the knowledge of the role played by OHS professionals in the transfer of the safety training they prepare and deliver in organizations as in-house trainers, in the context of their overall activity. The influences of other environmental and individual factors unexplored in the study of the transfer process are also examined. The present thesis is divided in five chapters that comprehend a review of literature about professional training and safety training, mainly focusing on the transfer problematic and the factors that affect it (Chapters 1 and 2), and three empirical studies that analyze different angles of the same phenomenon (Chapters 3, 4 and 5). The importance of the safety training transfer problematic is enhanced as well as the factors that may determine the success of interventions. From a theoretical point of view, the present work provides several major contributions, in particular: it unveils how OHS professionals, through their safety-related interactions with employees’ in the work environment, can influence the transfer of safety training and how they perceive their role in the process; it reveals the effect of felt-responsibility in the transfer process, as a psychological mechanism that affect both the trainers’ support toward transfer and the trainees’ effort to apply the safety training in-the-job. Regarding the practical contributions, this thesis suggests important strategies to the training design and management in organizations that can improve the safety training success.A presente tese tem como principal finalidade contribuir para o conhecimento sobre o papel desempenhado pelos profissionais de SST na transferência da formação que preparam e ministram aos trabalhadores, no âmbito do seu trabalho nas organizações. São ainda analisadas influências de fatores ambientais e individuais no processo de transferência ainda inexploradas pela investigação. Para o efeito estruturámos a tese em cinco capítulos que incluem: uma revisão da literatura sobre a formação profissional, em geral e no domínio específico da saúde e segurança no trabalho, com particular enfoque na problemática da transferência da formação e dos fatores que a afetam (capítulos 1 e 2); três estudos empíricos que analisam diferentes dimensões do mesmo fenómeno (capítulos 3, 4 e 5). A importância do tópico da transferência da formação em saúde e segurança no trabalho é realçada tal como a dos fatores que determinam o sucesso das intervenções. De um ponto de vista teórico, a tese proporciona como principais contributos: um conhecimento sobre como os profissionais de SST podem influenciar, através das interações que estabelecem com os trabalhadores, no âmbito do sistema de gestão da SST das organizações, a utilização das aprendizagens realizadas na formação; revela o efeito do sentido de responsabilidade no processo de transferência, enquanto mecanismo psicológico que afeta tanto o apoio prestado pelo profissional de SST à transferência como o esforço dos formandos em aplicar no trabalho os adquiridos na formação. No que respeita aos contributos práticos, a tese sugere importantes estratégias para o desenho e gestão das intervenções formativas em saúde e segurança no trabalho nas organizações

Space and Earth Sciences, Computer Systems, and Scientific Data Analysis Support, Volume 1

This Final Progress Report covers the specific technical activities of Hughes STX Corporation for the last contract triannual period of 1 June through 30 Sep. 1993, in support of assigned task activities at Goddard Space Flight Center (GSFC). It also provides a brief summary of work throughout the contract period of performance on each active task. Technical activity is presented in Volume 1, while financial and level-of-effort data is presented in Volume 2. Technical support was provided to all Division and Laboratories of Goddard's Space Sciences and Earth Sciences Directorates. Types of support include: scientific programming, systems programming, computer management, mission planning, scientific investigation, data analysis, data processing, data base creation and maintenance, instrumentation development, and management services. Mission and instruments supported include: ROSAT, Astro-D, BBXRT, XTE, AXAF, GRO, COBE, WIND, UIT, SMM, STIS, HEIDI, DE, URAP, CRRES, Voyagers, ISEE, San Marco, LAGEOS, TOPEX/Poseidon, Pioneer-Venus, Galileo, Cassini, Nimbus-7/TOMS, Meteor-3/TOMS, FIFE, BOREAS, TRMM, AVHRR, and Landsat. Accomplishments include: development of computing programs for mission science and data analysis, supercomputer applications support, computer network support, computational upgrades for data archival and analysis centers, end-to-end management for mission data flow, scientific modeling and results in the fields of space and Earth physics, planning and design of GSFC VO DAAC and VO IMS, fabrication, assembly, and testing of mission instrumentation, and design of mission operations center

The Prevalence of Religious Service Attendance in America: A Review and Meta-Analysis

The Gallup Poll and General Social Survey have asked Americans about their religious service attendance since 1939 and 1972, respectively. With remarkable consistency, these two surveys have estimated that just over 40% of the American population regularly attends religious services. Yet, recent research has called this “gold standard” into question, citing three sources of bias in these estimates: (a) ambiguous item wording, (b) an ambiguously specified time frame; and (c) data collection methods that lend themselves to socially desirable responding. Several lines of research have developed to eliminate or minimize these sources of bias, but these efforts have yielded a wide variety of results, with some estimates being half as much as the gold standard! Methodological and psychometric differences are not the only source of variation, however. The characteristics of those sampled into studies also introduces variability. Given that attendance estimates are likely influenced by variations in both methodology and sampling, this study uses meta-analytic techniques to estimate the extent of their influence and to estimate the attendance rate after controlling for their influence. The findings indicate that efforts to reduce socially desirable responding have had the greatest impact on the attendance rate, followed by efforts to overcome the ambiguously specified time-frame. In addition, attendance rates are positively related to the proportion of African Americans, Whites and married respondents sampled, as well as mean years of education. Attendance rates are also negatively related to the proportion of 18 to 30 year-old respondents sampled. After controlling for these methodological and socio-demographic study characteristics, the prevalence of weekly attendance in America was variously estimated as 41.4% for the gold standard items, 43.1% for items measuring attendance in the past week, 27.8% when asking respondents what they did yesterday (i.e., on Sunday via the time-use methodology) and 22.7% when attendance was counted manually

Beliefs and attitudes in judo coaching : toward a new model of coaching

The purpose of this research programme was to propose a new structure for judo coaching. Judo coaching predominantly uses traditional methods emphasising progression through belts rather than success in competition as the measure of achievement. The research programme examined this issue in four stages involving seven studies. Stage 1 involved a qualitative examination of five elite coaches on what constitutes an effective coach, leading to the initial development of a 39-item judo coaching scale. Given the importance of demonstrating measures are valid, stage 2 investigated the validity of the scale among judo players and coaches. Factor analytic studies on data from 260 (130 coaches and 130 players) yielded a 7-factor solution; 1) Coaching is about winning, 2) Attitudes to coaching at different levels, 3) Attitudes to judo structure, 4) Relationships with players, 5) Presentational issues, 6) Technical knowledge link to coach level, and 7) Coach-player interactions. Multisample confirmatory factor analysis found support for the invariance of the model between coaches and players, thereby showing that relationships are consistent between different groups. Stage 3 used a multi-method approach, combining quantitative and qualitative methods. Responses to the judo coaching scale indicated perceptions of coach effectiveness vary as a function of being a player or a coach, and by level of participation (elite-v-non-elite). Qualitative results emphasise the importance of emotional control, an aspect not focused on in the interviews completed in stage 1. Stage 4 of the research investigated relationships between judo coaching scale scores and emotional intelligence. The study also investigated levels of emotional intelligence between elite and club coaches. High emotional intelligence is associated is proposed to be indicative of being able to manage the emotional states of other people and so should be a desirable quality in coaches. Results show significant relationship between judo coaching scale score and emotional intelligence factors, with further analysis showing that elite coaches reported higher emotional intelligence scores than club coaches. Based on the findings from the studies completed above, a revised judo coaching structure is presented. An elite structure should be based on players having specific performance targets including technical and tactical skills, psychological, and physiological, aligning judo more closely with the structure used in other Olympic sports. Coaches should also be given targets related to developing emotional control among players and instilling players with a self-belief to attain performance targets related to the above. Effective integration and usage of such personnel is required including developing and inculcating sport science knowledge into the practice of elite coaches, and then modifying this knowledge for use in the club system. It is hoped that findings from this research stimulates discussion, and action in the British Judo Association to revise the current system, which could lead to better judo coaching, better players, and ultimately enhanced Olympic success at London 2012.EThOS - Electronic Theses Online ServiceGBUnited Kingdo