Feature Selection via Coalitional Game Theory

We present and study the contribution-selection algorithm (CSA), a novel algorithm for feature selection. The algorithm is based on the multiperturbation shapley analysis (MSA), a framework that relies on game theory to estimate usefulness. The algorithm iteratively estimates the usefulness of features and selects them accordingly, using either forward selection or backward elimination. It can optimize various performance measures over unseen data such as accuracy, balanced error rate, and area under receiver-operator-characteristic curve. Empirical comparison with several other existing feature selection methods shows that the backward elimination variant of CSA leads to the most accurate classification results on an array of data sets

Control of Bremia lactucae in Field-Grown Lettuce by DL-3-Amino-n-Butanoic Acid (BABA)

DL-3-amino-n-butanoic acid (BABA) was effective in controlling downy mildew incited by Bremia lactucae Regel in lettuce plants. The two isomers of BABA, DL-2-amino-n-butanoic acid and 4-amino-butanoic acid and its s-enantiomer were ineffective compares to BABA, while the r-enantiomer was more effective. The SAR compound NaSA and its functional analogue BTH (Bion) were also ineffective compared to BABA. In growth chambers, BABA was effective when applied as a foliar spray or as a soil drench. Effective control of the disease was apparent when BABA was applied up to 5 days before inoculation or 3 days after inoculation. A foliar spray of 125 mg/L reduced disease by 50% and full control of the disease was achieved with 500 mg/L. A soil drench with 1.25 mg /pot was required for >90% control the disease. In the field, 2-4 sprays with 1g/L BABA reduced disease severity by 90% as compared to control untreated plants. BABA had no adverse effect on sporangial germination of Bremia lactucae in vitro, germination on plant leaf surface or, fungal penetration into the host. However, it prevented the colonization of the host with the pathogen.

The Effect of Common Signals on Power, Coherence and Granger Causality: Theoretical Review, Simulations, and Empirical Analysis of Fruit Fly LFPs Data

When analyzing neural data it is important to consider the limitations of the particular experimental setup. An enduring issue in the context of electrophysiology is the presence of common signals. For example a non-silent reference electrode adds a common signal across all recorded data and this adversely affects functional and effective connectivity analysis. To address the common signals problem, a number of methods have been proposed, but relatively few detailed investigations have been carried out. As a result, our understanding of how common signals affect neural connectivity estimation is incomplete. For example, little is known about recording preparations involving high spatial-resolution electrodes, used in linear array recordings. We address this gap through a combination of theoretical review, simulations, and empirical analysis of local field potentials recorded from the brains of fruit flies. We demonstrate how a framework that jointly analyzes power, coherence, and quantities based on Granger causality reveals the presence of common signals. We further show that subtracting spatially adjacent signals (bipolar derivations) largely removes the effects of the common signals. However, in some special cases this operation itself introduces a common signal. We also show that Granger causality is adversely affected by common signals and that a quantity referred to as “instantaneous interaction” is increased in the presence of common signals. The theoretical review, simulation, and empirical analysis we present can readily be adapted by others to investigate the nature of the common signals in their data. Our contributions improve our understanding of how common signals affect power, coherence, and Granger causality and will help reduce the misinterpretation of functional and effective connectivity analysis

The role of Rap/Hip Hop music in the meaning and maintenance of identity in South African youth.

Although music has seemingly always formed an integral part of human culture, technological advances in contemporary society have increased both its accessibility and portability, allowing for unprecedented production and consumption of a medium that allows individuals to enact and display various social identities during day-to-day life. Furthermore, recent research has demonstrated that youth consume more music that any other age group. Thus music may be considered as a primary cultural influence in the lives of youth. While the bulk of the research conducted in understanding the form and function of this influence has been located in the disciplines of sociology and musicology, Psychologists in Europe and America have become increasingly interested in understanding the role of music in constructing and maintaining identity during this critical period of development. As a contribution to this field of application outside of these contexts and located within a qualitative framework, this study explored the role of Rap/Hip Hop music, as one of the most popular global and local genres of music, in the meaning and maintenance of identity in a cohort of South African youth. The resultant thematic framework illustrated the complex tensions negotiated by youth through assuming Hip Hop culture membership in South Africa. Importantly, the study showed that the nature of Hip Hop culture; its emphasis on self-expression, individuation and critical social awareness dovetails with many of the traditional psychological developmental theories of youth identity. Hip Hop consumption also implied appropriating identity markers from a wide range of social influences, posing challenges to the application of traditional social identity theory in accounting for in and out groupings. This was most pronounced in the way that ‘remixing’, as a governing musical principle in Hip Hop seems to resonate as key mode of identity and identification amongst its South African consumers. Thus, it seems fitting that South African youth currently in the midst of cultural, economic and political transitions would embrace an eclectic rather than rigidly bounded genre of music with such enthusiasm. In some ways then Hip Hop in South Africa, appears to provide youth with the means to remix past and present, old and new, global and local, self and other

General anesthesia reduces complexity and temporal asymmetry of the informational structures derived from neural recordings in Drosophila

We apply techniques from the field of computational mechanics to evaluate the statistical complexity of neural recording data from fruit flies. First, we connect statistical complexity to the flies' level of conscious arousal, which is manipulated by general anesthesia (isoflurane). We show that the complexity of even single channel time series data decreases under anesthesia. The observed difference in complexity between the two states of conscious arousal increases as higher orders of temporal correlations are taken into account. We then go on to show that, in addition to reducing complexity, anesthesia also modulates the informational structure between the forward- and reverse-time neural signals. Specifically, using three distinct notions of temporal asymmetry we show that anesthesia reduces temporal asymmetry on information-theoretic and information-geometric grounds. In contrast to prior work, our results show that: (1) Complexity differences can emerge at very short timescales and across broad regions of the fly brain, thus heralding the macroscopic state of anesthesia in a previously unforeseen manner, and (2) that general anesthesia also modulates the temporal asymmetry of neural signals. Together, our results demonstrate that anesthetized brains become both less structured and more reversible.Comment: 14 pages, 6 figures. Comments welcome; Added time-reversal analysis, updated discussion, new figures (Fig. 5 & Fig. 6) and Tables (Tab. 1

Cognitive Sub-Nyquist Hardware Prototype of a Collocated MIMO Radar

We present the design and hardware implementation of a radar prototype that demonstrates the principle of a sub-Nyquist collocated multiple-input multiple-output (MIMO) radar. The setup allows sampling in both spatial and spectral domains at rates much lower than dictated by the Nyquist sampling theorem. Our prototype realizes an X-band MIMO radar that can be configured to have a maximum of 8 transmit and 10 receive antenna elements. We use frequency division multiplexing (FDM) to achieve the orthogonality of MIMO waveforms and apply the Xampling framework for signal recovery. The prototype also implements a cognitive transmission scheme where each transmit waveform is restricted to those pre-determined subbands of the full signal bandwidth that the receiver samples and processes. Real-time experiments show reasonable recovery performance while operating as a 4x5 thinned random array wherein the combined spatial and spectral sampling factor reduction is 87.5% of that of a filled 8x10 array.Comment: 5 pages, Compressed Sensing Theory and its Applications to Radar, Sonar and Remote Sensing (CoSeRa) 201

Minimum Neighboring Degree Realization in Graphs and Trees

We study a graph realization problem that pertains to degrees in vertex neighborhoods. The classical problem of degree sequence realizability asks whether or not a given sequence of n positive integers is equal to the degree sequence of some n-vertex undirected simple graph. While the realizability problem of degree sequences has been well studied for different classes of graphs, there has been relatively little work concerning the realizability of other types of information profiles, such as the vertex neighborhood profiles. In this paper we introduce and explore the minimum degrees in vertex neighborhood profile as it is one of the most natural extensions of the classical degree profile to vertex neighboring degree profiles. Given a graph G = (V,E), the min-degree of a vertex v ? V, namely MinND(v), is given by min{deg(w) ? w ? N[v]}. Our input is a sequence ? = (d_?^{n_?}, ?d?^{n?}), where d_{i+1} > d_i and each n_i is a positive integer. We provide some necessary and sufficient conditions for ? to be realizable. Furthermore, under the restriction that the realization is acyclic, i.e., a tree or a forest, we provide a full characterization of realizable sequences, along with a corresponding constructive algorithm. We believe our results are a crucial step towards understanding extremal neighborhood degree relations in graphs