Recasting covert visual attention effects from the perspective of fixational oculomotor dynamics: Theory and experiments

Traditionally, a great many studies of visual attention have used reaction time measures (either with manual button presses or saccadic eye movements) to make inferences about the locus and time course of attentional allocation. One classic example of such studies is the Posner cueing paradigm (Posner 1980), in which subjects maintain fixation and a cue is presented on one side or the other of space; a post-cue target appearing at different times and locations is used to elicit a reaction time and map the spatial and temporal development of cue-induced changes in internal brain state. However, tasks with prolonged fixation inevitably involve fixational eye movements, like microsaccades. Since microsaccades are the same as saccades, and are therefore associated with peri-movement changes in internal brain state, an imperative question we should ask is: how much of performance changes in tasks like Posner cueing may actually be attributable to peri-movement changes in vision associated with microsaccades? And, if this turns out to be a real, plausible possibility, can we predict, on a trial-by-trial basis, when and where microsaccades can occur, and therefore when and where performance changes in Posner cueing might be expected to take place? In order to investigate these questions, we started our Study I, which is a combined study including modeling simulations and behavioral psychophysics. Based on a minimalist model of oculomotor generation (microsaccades) without any other factors (i.e. knowledge about where attention is “supposed” to be allocated), we successfully simulated attentional effects and replicated all detailed observations in the classic Posner cueing paradigm. This means that from a theoretical perspective, classic concepts in cognitive neuroscience like “attentional capture (AC)” and “Inhibition of return (IOR)” become the outcomes of peri-microsaccadic enhancement or suppression of neural visual sensitivity. We next turned to the question of why microsaccades might be modulated in Posner cueing at all; can we predict when and where microsaccades should be seen? In Study II, we experimentally controlled instantaneous foveal motor error during the presentation of peripheral cues. Post-cue microsaccadic oscillations were severely disrupted, suggesting that microsaccades in Posner cueing occur for oculomotor control over foveal motor error and not necessarily because they form a “dirty” read-out of covert attention, as commonly assumed. We then went one step further in Study III, in which we delved deeper into the mechanisms for fixational eye position dynamics, and how they dictate when microsaccades occur (and therefore when performance changes in Posner cueing might be expected). We discovered a new phenomenon of “express microsaccades” that were highly precise in time and direction. We used this discovery to refine our understanding of why microsaccades might be triggered during Posner cueing, showing that there is an oculomotor “set point” that is very systematically modulated at different times after cue onset, and that the instantaneous relationship between eye position and this set point is sufficient to explain when and where microsaccades would be observed. Overall, our work takes a classic phenomenon in cognitive neuroscience, covert attention as studied with Posner cueing, and significantly recasts it from a completely different perspective related to the highly detailed workings of the oculomotor system during the simple act of gaze fixation. Our work has significant implications on potential neural correlates of covert visual attention and fixational eye position dynamics in the brain

Millennials Acceptance of Insurance Telematics: An Integrative Empirical Study

Insurance telematics is a recent technology-enabled service innovation advanced by insurance companies and adopted by millions of drivers worldwide. This research study explores the insurance telematics technology acceptance and use among the new Millennials generation, which represents both a challenge and an opportunity for insurers. Drawing on the Technology Acceptance Model (TAM) and the Theory of Planned Behaviour (TPB), the study uses data from 138 Millennials in the USA to delve into their perceived attitudinal behavior and intention to use insurance telematics. The findings provide empirical confirmation of the integrative and predictive power of the proposed combined theoretical framework (TAM-TPB) to explain insurance telematics adoption and use. The results also suggest a sophistication-level shift in Millennials preferences from functionality evaluation to applicability value sought through the adoption and use. And the findings ascertain the role of perceived enjoyment, trust, and social media as critical factors influencing Millennials attitudinal behavior and intention to use insurance telematics. Considering these results, the authors further discuss implications for scholars and practitioners, and suggest future research directions

Exopolysaccharide Produced by Pediococcus pentosaceus E8 : Structure, Bio-Activities, and Its Potential Application

The novel exopolysaccharide EPS-E8, secreted by Pediococcus pentosaceus E8, was obtained by anion-exchange and gel filtration chromatography. Structural analyses identified EPS-E8 as a heteropolysaccharide containing mannose, glucose, and galactose. Its major backbone consists of -> 2)-alpha-D-Manp-(1 -> 2,6)-alpha-D-Glcp-(1 -> 6)-alpha-D-Manp-(1 ->, and its molecular weight is 5.02 x 10(4) g/mol. Using atomic force microscopy and scanning electron microscopy, many spherical and irregular reticular-like shapes were observed in the microstructure of EPS-E8. EPS-E8 has outstanding thermal stability (305.7 degrees C). Both the zeta potential absolute value and average particle diameter increased gradually with increasing concentration. Moreover, at a concentration of 10 mg/ml, the antioxidant capacities of, 1-Diphenyl-2-picrylhydrazyl (DPPH), ABTS and hydroxyl radical were 50.62 +/- 0.5%, 52.17 +/- 1.4%, and 58.91 +/- 0.7%, respectively. EPS-E8 possesses excellent emulsifying properties against several food-grade oils, and its activity is retained under various conditions (temperature, pH, and ionic strength). Finally, we found that EPS-E8 as a polysaccharide-based coating could reduce the weight loss and malondialdehyde (MDA) content of strawberry, as well as preserving the vitamin C and soluble solid content during storage at 20 degrees C. Together, the results support the potential application of EPS-E8 as an emulsifier, and a polysaccharide-based coating in fruit preservation.Peer reviewe

Millennials Acceptance of Insurance Telematics: An Integrative Empirical Study

Insurance telematics is a recent technology-enabled service innovation advanced by insurance companies and adopted by millions of drivers worldwide. This research study explores the insurance telematics technology acceptance and use among the new Millennials generation, which represents both a challenge and an opportunity for insurers. Drawing on the Technology Acceptance Model (TAM) and the Theory of Planned Behaviour (TPB), the study uses data from 138 Millennials in the USA to delve into their perceived attitudinal behavior and intention to use insurance telematics. The findings provide empirical confirmation of the integrative and predictive power of the proposed combined theoretical framework (TAM-TPB) to explain insurance telematics adoption and use. The results also suggest a sophistication-level shift in Millennials preferences from functionality evaluation to applicability value sought through the adoption and use. And the findings ascertain the role of perceived enjoyment, trust, and social media as critical factors influencing Millennials attitudinal behavior and intention to use insurance telematics. Considering these results, the authors further discuss implications for scholars and practitioners, and suggest future research directions

High sensitivity micro-fiber Mach-Zehnder interferometric temperature sensors with a high index ring layer

The influence of the high index ring layer (HIRL) in a tapered fiber Mach-Zehnder interferometer (MZI) on the interference observed, and thus on its potential applications in temperature sensing, has been investigated. The MZI was comprised of a tapered Ring Core Fiber (RCF), spliced between two single mode fibers (SMF). Since part of core mode from the SMF was converted into cladding modes in the RCF, due to the mismatch in the cores between the RCF and SMF, the residual power enters and then propagates along the center of the RCF (silica). The difference in phase between the radiation travelling along these different paths is separated by the HIRL to generate an interference effect. Compared with fiber interferometers based on core and cladding mode interference, the thin fiber HIRL is capable of separating the high order cladding modes and the silica core mode, under grazing incident conditions. Therefore, the optical path difference (OPD) and the sensitivity are both substantially improved over what is seen in conventional devices, showing their potential for interferometric temperature sensor applications. The optimum temperature sensitivity obtained was 186.6 pm/°C, which is ∼ 11.7 times higher than has been reported previously

Anti-disturbance sliding mode based deadbeat direct torque control for PMSM speed regulation system

Deadbeat direct torque control (DBDTC) calculates the voltage vector based on the motor mathematical model and tracks the torque and flux reference within only one sampling cycle. However, in the traditional DBDTC, the reference torque is generated by a speed PI controller, which presents a low dynamic and poor precision, particularly under external disturbances. To sort out this issue, this paper proposes an improved DBDTC control method basing on the sliding mode strategy. First, an anti-disturbance sliding mode controller (ASMC) is presented which is superior in offering a fast and accurate reference torque for DBDTC. Along the way, an extended sliding mode disturbance observer is introduced which estimates total disturbances and compensates the sliding mode controller. To reduce the chattering of sliding mode control, a novel reaching law is proposed. This novel reaching law introduces system state variable in the exponential terms of power reaching law, and meanwhile including an adaptive exponential reaching action. By this means, it increases system convergence rate to the sliding mode surface while suppressing sliding mode chattering. Finally, both simulation and experimental results show that the proposed control method has better performance in terms of torque ripple reduction, speed dynamic response