Boosted Random ferns for object detection

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper we introduce the Boosted Random Ferns (BRFs) to rapidly build discriminative classifiers for learning and detecting object categories. At the core of our approach we use standard random ferns, but we introduce four main innovations that let us bring ferns from an instance to a category level, and still retain efficiency. First, we define binary features on the histogram of oriented gradients-domain (as opposed to intensity-), allowing for a better representation of intra-class variability. Second, both the positions where ferns are evaluated within the sliding window, and the location of the binary features for each fern are not chosen completely at random, but instead we use a boosting strategy to pick the most discriminative combination of them. This is further enhanced by our third contribution, that is to adapt the boosting strategy to enable sharing of binary features among different ferns, yielding high recognition rates at a low computational cost. And finally, we show that training can be performed online, for sequentially arriving images. Overall, the resulting classifier can be very efficiently trained, densely evaluated for all image locations in about 0.1 seconds, and provides detection rates similar to competing approaches that require expensive and significantly slower processing times. We demonstrate the effectiveness of our approach by thorough experimentation in publicly available datasets in which we compare against state-of-the-art, and for tasks of both 2D detection and 3D multi-view estimation.Peer ReviewedPostprint (author's final draft

Cumulative object categorization in clutter

In this paper we present an approach based on scene- or part-graphs for geometrically categorizing touching and occluded objects. We use additive RGBD feature descriptors and hashing of graph configuration parameters for describing the spatial arrangement of constituent parts. The presented experiments quantify that this method outperforms our earlier part-voting and sliding window classification. We evaluated our approach on cluttered scenes, and by using a 3D dataset containing over 15000 Kinect scans of over 100 objects which were grouped into general geometric categories. Additionally, color, geometric, and combined features were compared for categorization tasks

Neurobiological markers for remission and persistence of childhood attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in children. Symptoms of childhood ADHD persist into adulthood in around 65% of patients, which elevates the risk for a number of adverse outcomes, resulting in substantial individual and societal burden. A neurodevelopmental double dissociation model is proposed based on existing studies in which the early onset of childhood ADHD is suggested to associate with dysfunctional subcortical structures that remain static throughout the lifetime; while diminution of symptoms over development could link to optimal development of prefrontal cortex. Current existing studies only assess basic measures including regional brain activation and connectivity, which have limited capacity to characterize the functional brain as a high performance parallel information processing system, the field lacks systems-level investigations of the structural and functional patterns that significantly contribute to the symptom remission and persistence in adults with childhood ADHD. Furthermore, traditional statistical methods estimate group differences only within a voxel or region of interest (ROI) at a time without having the capacity to explore how ROIs interact in linear and/or non-linear ways, as they quickly become overburdened when attempting to combine predictors and their interactions from high-dimensional imaging data set. This dissertation is the first study to apply ensemble learning techniques (ELT) in multimodal neuroimaging features from a sample of adults with childhood ADHD and controls, who have been clinically followed up since childhood. A total of 36 adult probands who were diagnosed with ADHD combined-type during childhood and 36 matched normal controls (NCs) are involved in this dissertation research. Thirty-six adult probands are further split into 18 remitters (ADHD-R) and 18 persisters (ADHD-P) based on the symptoms in their adulthood from DSM-IV ADHD criteria. Cued attention task-based fMRI, structural MRI, and diffusion tensor imaging data from each individual are analyzed. The high-dimensional neuroimaging features, including pair-wise regional connectivity and global/nodal topological properties of the functional brain network for cue-evoked attention process, regional cortical thickness and surface area, subcortical volume, volume and fractional anisotropy of major white matter fiber tract for each subject are calculated. In addition, all the currently available optimization strategies for ensemble learning techniques (i.e., voting, bagging, boosting and stacking techniques) are tested in a pool of semi-final classification results generated by seven basic classifiers, including K-Nearest Neighbors, support vector machine (SVM), logistic regression, Naïve Bayes, linear discriminant analysis, random forest, and multilayer perceptron. As hypothesized, results indicate that the features of nodal efficiency in right inferior frontal gyrus, right middle frontal (MFG)-inferior parietal (IPL) functional connectivity, and right amygdala volume significantly contributed to accurate discrimination between ADHD probands and controls; higher nodal efficiency of right MFG greatly contributed to inattentive and hyperactive/impulsive symptom remission, while higher right MFG-IPL functional connectivity strongly linked to symptom persistence in adults with childhood ADHD. The utilization of ELTs indicates that the bagging-based ELT with the base model of SVM achieves the best results, with the most significant improvement of the area under the receiver of operating characteristic curve (0.89 for ADHD probands vs. NCs, and 0.9 for ADHD-P vs. ADHD-R). The outcomes of this dissertation research have considerable value for the development of novel interventions that target mechanisms associated with recovery

Audition, learning and experience: expertise through development

Our experience with the auditory world can shape and modify perceptual, cognitive and neural processes with respect to audition. Such experience can occur over multiple timescales, and can vary in its specificity and intensity. In order to understand how auditory perceptual, cognitive and neural processes develop, it is important to explore the different means through which experience can influence audition. This thesis aims to address these issues. Using an expertise framework, we explore how the auditory environment and ontogenetic factors can shape and guide perceptual, cognitive and neural processes through long- and short-term profiles of experience. In early chapters, we use expertly-trained musicians as a model for long-term experience accrued under specific auditory constraints. We find that expertise on a particular instrument (violin versus piano) yields training-specific auditory perceptual advantages in a musical context, as well as improvements to ‘low-level’ auditory acuity (versus non-musicians); yet we find limited generalisation of expertise to cognitive tasks that require some of the skills that musicians hone. In a subsequent chapter, we find that expert violinists (versus non-musicians) show subtle increases in quantitative MR proxies for cortical myelin at left auditory core. In latter chapters, we explore short-term sound learning. We ask whether listeners can learn combinations of auditory cues within an active visuo-spatial task, and whether development can mediate learning of auditory cue combinations or costs due to cue contingency violations. We show that auditory cue combinations can be learned within periods of minutes. However, we find wide variation in cue learning success across all experiments, with no differences in overall cue combination learning between children and adults. These experiments help to further understanding of auditory expertise, learning, development and plasticity, within an experience-based framework

A critical analysis of the Kiba (song-dance-drama) discourse

1 Aim The aim of the research is to map out the theoretical construct of Kiba from practice. The analysis includes the mapping out of the metalanguage of the theory used by its practitioners. Therefore the research will map out a theory of Kiba not as a generic hypothetical theory of music and dance, but as a theory that describes actual performance. The research aims to achieve this not only through the description of what practitioners do in actual performance, but also through analysing the language behaviour and principles that govern the making of the performance discourse. The research will also look into the dynamic nature of culture and the challenges of ownership and rights that emerge. The analysis starts by tracing social practices and ethics that influence dance, drumming, music making, praise, and design of costume used in contemporary Kiba. It also looks at compositional structures, aesthetic elements, and principles governing the communicative competence of Kiba. The research presents the texts in Sepedi with English translations. It focuses on the description and analysis of principles governing the production and management of the discourse. Though the analysis focuses on the communicative function and value of Kiba, its main thrust is on principles that govern the making of the integral communication. The researcher uses mainly the performers' interpretation of the Kiba performance theory, as well as approaches to the analysis of cultural context of communication espoused by Hymes (1970) and Saville-Troike (1989). 2 Hypothesis If Kiba practice theory is not developed, then Kiba will not find access into the mainstream of Arts and Culture curricula at all levels of education. The chances of it competing successfully in economic markets of the Arts and Culture will not see the light of day. 3 Methods and procedures Kiba is a complex genre. The analysis of its performance discourse, that is, its dance-drama and praise-song of Kiba requires an interdisciplinary approach. This will be particularly useful in the analysis of the dance sequence structure with its dramatic effect, and of the principles governing the choices of repertoire and music elements. Barber (1989:13) supports this approach for the analysis of complex genres. She points out that: There is an obvious and very good reason for taking an interdisciplinary approach to African oral texts, and that is that the texts themselves can combine 'literature', 'history', 'music', 'religion' and other things. The unity of these fields within oral texts suggests that the method of interpretation should also be unified. Rather than collaboration between specialists from different disciplines, what is needed is the reintegration of an artificially divided field. It is crucial to state from the outset that the research does not perceive Kiba as music or art, but as a way of lived communication and it echoes the observation made by Agawu (2002: 452) that: ... in many African languages, there is no single word for 'music' that the term is semantically dispersed across many fields often indexing dancing or movement as well as the actual sound produced. However, since the overall vehicle of a Kiba performance is presented in songdance, the research will trace the 'musical' and not the 'music' elements of Kiba. Nevertheless it does make a conscious effort to strike a balance between the musical, literary, dance, and the philosophical. iii In Sepedi as well as the broad Sotho languages, the word for music is 'mmino'. This refers to both song and dance. This concept will be represented in the research as 'song-dance'. Therefore, a multidisciplinary approach to the study of Kiba will prove to be more useful than an approach to music or just dance elements of Kiba. An analysis of the co-operative principles that underpin the Kiba discourse, and the cultural and compositional elements of Kiba will form part of the interdisciplinary approach to the study of Kiba. The research will also use elements of sociolinguistics, cantometrics, ethnomethodology and ethnomusicology to analyse Kiba discourse. iv 4 Procedures: focus areas of the research The entire inquiry obtained data from participants through unstructured interviews and observation of the language behaviour of Kiba interlocutors. Observation and interviews were carried out in ten villages. The basic questions and the researcher's observation of live performance of Kiba focused on the three main areas of the research: compositional structure, aesthetic elements, and principles governing the actual performance. The latter refers to the norms and standards of interaction in, and interpretation of, Kiba discourse. The basic questions that are asked are: Definition of Kiba □ Kiba ke eng?I What is Kiba? ✓ A Kiba ke ya banna goba ke ya basadi?l ls Kiba a male or female genre? ✓ A Kiba ke ya baswa goba ke ya batho ba bagolo? /Is Kiba a youth or adult genre? Compositional and aesthetic elements: □ Ge le bina Kiba le dira eng? I What are the structural elements of Kiba? □ Mekgwa ya go natefisa kosa ke efe? /What are the ways of embellishing a song? □ Diletso tse di diriswago mo Kibeng ke dife? I What resources are used in the Kiba communication system? Which principles govern actual performance communication? Examine the following: □ Poledisano le kgolagano ya kosa magareng a malokwane le sehlopha, le magareng ga sehlopha le babogedi goba setshaba? I The discourse structure of the Kiba intra-communication system: analysis of the intercommunication strategies between the Kiba participants as addressers and an individual or a community as addressee(s). V □ A Kiba ke ya Bapedi goba ke Sepedi? Is Kiba a genre of the Bapedi or is it Sepedi? Translated texts appear beneath the original texts. Original texts appear in italics, while translations are typed in normal font as Mason (interview: Washington DC, June 1997) advises. Vernacular names and words are used and explained in context. Single word expressions and exclamations have been retained and their explanations are given in square brackets. A glossary of terms has been provided at the end of the thesis. 5 Abbreviated thesis Accompanying the research is an audio-visual presentation that shows the · prototype of an integral and fully expanded discourse of Kiba. The video is intended to help the reader and viewer to understand performance nuances of dance, drumming, voice technique, and the use of colour. The audiovisual excerpt of an exemplary performance of Kiba is provided as annexure 4. The latter is an authentic text that shows a royal ensemble, led by Chief Ramokgopa during his official visit to the royal capital of Moletsi on 1 January 1999. The excerpt shows every aspect of Kiba raised by the research. vi There are also accompanying compact discs, which reveal the conscious attempt to further develop Kiba into a modern competitive format called FreeKiba. (See the copies of the themes presented in annexure I, and the two CDs that are provided as part of annexure 4). Agawu (2002:47) perceives this kind of an adaptation as progressive in that it is premised on the agenda of the emancipation of African music. He puts it succinctly: The emancipation of African music begins precisely at the point where our priorities shift from valuing present realities to constructing future possibilities. This view is also held by Nzewi (1980, 1983). 6 Conclusion The research will use ethnomusicology to analyse participants' use of song, dance, drama, drumming and praise-singing as integral constituents of Kiba. To analyse the Kiba discourse structure, the research will use the 'ethnography of communication method. The method is useful in the analysis principles governing the appropriateness of lived communication (Hymes 1964). It also requires principles of ethnomethodology to be used to 'discover what methods [Kiba] practitioners use to participate in and make sense of interactions of thei

Divergence in potential contact pheromones and genital morphology among sympatric song types of the bush cricket Mecopoda elongata

This is the final version. Available from Frontiers Media via the DOI in this record. A well-established route to speciation in animals is via the evolution of divergent male mating signals and female preferences within a species. However, an open question is how common it is for near complete isolation to be achieved through a single signal-receiver system as opposed to multiple aspects of the mate-recognition system diverging simultaneously. The five highly divergent mate-attraction song types of the bush cricket Mecopoda elongata exemplify reproductive isolation in sympatry through long-distance mating signals. Female preference for their own song type has been established as a strong pre-mating reproductive barrier, but the potential existence of additional isolating mechanisms has not been investigated. We quantify divergence in cuticular lipid profiles and external genital structures between song types. These traits show significant variation among species of Orthoptera and are known to be used in mate recognition following contact. We show that divergence among sympatric Mecopoda song types in both cuticular lipid profiles and two external genital structures is sufficiently extensive that either of them can be used to identify individual song type with 90% accuracy. Our findings suggest that multiple isolating mechanisms are likely to evolve simultaneously facilitating a more robust reproductive isolation. Our study indicates a role for sexual selection in the divergence and potential future speciation of these populations and suggests that reproductive isolation may frequently evolve through simultaneous divergence across different aspects of mate recognition systems.University of Exete