Bearing-only acoustic tracking of moving speakers for robot audition

This paper focuses on speaker tracking in robot audition for human-robot interaction. Using only acoustic signals, speaker tracking in enclosed spaces is subject to missing detections and spurious clutter measurements due to speech inactivity, reverberation and interference. Furthermore, many acoustic localization approaches estimate speaker direction, hence providing bearing-only measurements without range information. This paper presents a probability hypothesis density (PHD) tracker that augments the bearing-only speaker directions of arrival with a cloud of range hypotheses at speaker initiation and propagates the random variates through time. Furthermore, due to their formulation PHD filters explicitly model, and hence provide robustness against, clutter and missing detections. The approach is verified using experimental results

Microphone array signal processing for robot audition

Robot audition for humanoid robots interacting naturally with humans in an unconstrained real-world environment is a hitherto unsolved challenge. The recorded microphone signals are usually distorted by background and interfering noise sources (speakers) as well as room reverberation. In addition, the movements of a robot and its actuators cause ego-noise which degrades the recorded signals significantly. The movement of the robot body and its head also complicates the detection and tracking of the desired, possibly moving, sound sources of interest. This paper presents an overview of the concepts in microphone array processing for robot audition and some recent achievements

Molecular and chemical characterization of vetiver, Chrysopogon zizanioides (L.) Roberty, germplasm

Due to the economic interests in vetiver, Chrysopogon zizanioides (L.) Roberty, molecular and chemical studies are essential to generate information for its sustainable exploitation. The aim of this study was to undertake a molecular and chemical characterization of vetiver accessions of the active germplasm bank of the Universidade Federal de Sergipe. The molecular characteristics of the accessions were studied using amplified fragment length polymorphism markers, with a total of 14 primer combinations that generated 442 loci, allowing us to observe that these accessions have similar genomes. The vetiver accessions were divided into three distinct groups, where accession UFS-VET005 was the most differentiated and accession UFS-VET004 had the lowest essential oil content (0.70%). The content of the chemical constituents of the essential oils was observed to vary, with a predominance of khusimol, which ranged from 18.97 to 25.02%. It was possible to divide the vetiver accessions into two groups based on chemical composition, and these groups do not correlate with the molecular grouping. Therefore, it is necessary to perform molecular and chemical analyses to characterize vetiver accessions

Molecular and chemical characterization of vetiver, Chrysopogon zizanioides (L.) Roberty, germplasm

Due to the economic interests in vetiver, Chrysopogon zizanioides (L.) Roberty, molecular and chemical studies are essential to generate information for its sustainable exploitation. The aim of this study was to undertake a molecular and chemical characterization of vetiver accessions of the active germplasm bank of the Universidade Federal de Sergipe. The molecular characteristics of the accessions were studied using amplified fragment length polymorphism markers, with a total of 14 primer combinations that generated 442 loci, allowing us to observe that these accessions have similar genomes. The vetiver accessions were divided into three distinct groups, where accession UFS-VET005 was the most differentiated and accession UFS-VET004 had the lowest essential oil content (0.70%). The content of the chemical constituents of the essential oils was observed to vary, with a predominance of khusimol, which ranged from 18.97 to 25.02%. It was possible to divide the vetiver accessions into two groups based on chemical composition, and these groups do not correlate with the molecular grouping. Therefore, it is necessary to perform molecular and chemical analyses to characterize vetiver accessions

Decision making under time pressure: An independent test of sequential sampling models

Choice probability and choice response time data from a risk-taking decision-making task were compared with predictions made by a sequential sampling model. The behavioral data, consistent with the model, showed that participants were less likely to take an action as risk levels increased, and that time pressure did not have a uniform effect on choice probability. Under time pressure, participants were more conservative at the lower risk levels but were more prone to take risks at the higher levels of risk. This crossover interaction reflected a reduction of the threshold within a single decision strategy rather than a switching of decision strategies. Response time data, as predicted by the model, showed that participants took more time to make decisions at the moderate risk levels and that time pressure reduced response time across all risk levels, but particularly at the those risk levels that took longer time with no pressure. Finally, response time data were used to rule out the hypothesis that time pressure effects could be explained by a fast-guess strategy