No-Sense: Sense with Dormant Sensors

Wireless sensor networks (WSNs) have enabled continuous monitoring of an area of interest (body, room, region, etc.) while eliminating expensive wired infrastructure. Typically in such applications, wireless sensor nodes report the sensed values to a sink node, where the information is required for the end-user. WSNs also provide the flexibility to the end-user for choosing several parameters for the monitoring application. For example, placement of sensors, frequency of sensing and transmission of those sensed data. Over the years, the advancement in embedded technology has led to increased processing power and memory capacity of these battery powered devices. However, batteries can only supply limited energy, thus limiting the lifetime of the network. In order to prolong the lifetime of the deployment, various efforts have been made to improve the battery technologies and also reduce the energy consumption of the sensor node at various layers in the networking stack. Of all the operations in the network stack, wireless data transmission and reception have found to consume most of the energy. Hence many proposals found in the literature target reducing them through intelligent schemes like power control, reducing retransmissions, etc. In this article we propose a new framework called Virtual Sensing Framework (VSF), which aims to sufficiently satisfy application requirements while conserving energy at the sensor nodes.Comment: Accepted for publication in IEEE Twentieth National Conference on Communications (NCC-2014

Physical and neural entrainment to rhythm: human sensorimotor coordination across tasks and effector systems.

The human sensorimotor system can be readily entrained to environmental rhythms, through multiple sensory modalities. In this review, we provide an overview of theories of timekeeping that make this neuroentrainment possible. First, we present recent evidence that contests the assumptions made in classic timekeeper models. The role of state estimation, sensory feedback and movement parameters on the organization of sensorimotor timing are discussed in the context of recent experiments that examined simultaneous timing and force control. This discussion is extended to the study of coordinated multi-effector movements and how they may be entrained

Fluorescence Imaging of Cortical Calcium Dynamics: A Tool for Visualizing Mouse Brain Functions, Connections, and Networks

Hemodynamic-based markers of cortical activity (e.g. functional magnetic resonance imaging (fMRI) and optical intrinsic signal imaging) are an indirect and relatively slow report of neural activity driven by electrical and metabolic activity through neurovascular coupling, which presents significant limiting factors in deducing underlying brain network dynamics. As application of resting state functional connectivity (FC) measures is extended further into topics such as brain development, aging, and disease, the importance of understanding the fundamental basis for FC will grow. In this dissertation, we extend functional analysis from hemodynamic- to calcium-based imaging. Transgenic mice expressing a fluorescent calcium indicator (GCaMP6) driven by the Thy1 promoter in glutamatergic neurons were imaged transcranially in both anesthetized (using ketaminze/xylazine) and awake states. Sequential LED illumination (λ=470, 530, 590, 625nm) enabled concurrent imaging of both GCaMP6 fluorescence emission (corrected for hemoglobin absorption) and hemodynamics. EEG measurements of the global cortical field potential were also simultaneously acquired. First, we validated the ability of our system to capture GCaMP6 fluorescence emission and hemodynamics by implementing an electrical somatosensory stimulation paradigm. The neural origins of the GCaMP6 fluorescent signal were further confirmed by histology and by comparing the spectral content of imaged GCaMP6 activity to concurrently-acquired EEG. We then constructed seed-based FC and coherence network maps for low (0.009-0.08Hz) and high, delta-band (0.4-4.0Hz) frequency bands using GCaMP6 and hemodynamic contrasts. Homotopic GCaMP6 FC maps using delta-band data in the anesthetized states show a striking correlated and anti-correlated structure along the anterior to posterior axis. We next used whole-brain delay analysis to characterize this correlative feature. This structure is potentially explained by the observed propagation of delta-band activity from frontal somatomotor regions to visuoparietal areas, likely corresponding to propagating delta waves associated with slow wave sleep. During wakefulness, this spatio-temporal structure is largely absent, and a more complex and detailed FC structure is observed. Collectively, functional neuroimaging of calcium dynamics in mice provides evidence that spatiotemporal coherence in cortical activity is not exclusive to hemodynamics and exists over a larger range of frequencies than hemoglobin-based contrasts. Concurrent calcium and hemodynamic imaging enables direct temporal and functional comparison of spontaneous calcium and hemoglobin activity, effectively spanning neurovascular coupling and functional hyperemia. The combined calcium/hemoglobin imaging technique described here will enable the dissociation of changes in ionic and hemodynamic functional structure and provide a framework for subsequent studies of sleep disorders and neurological disease

Quantifying Self Perception: Multisensory Temporal Asynchrony Discrimination As A Measure of Body Ownership

There are diffuse and distinct cortical networks involved in the various aspects of body representation that organize information from multiple sensory inputs and resolve conflicts when faced with incongruent situations. This coherence is typically maintained as we maneuver around the world, as our bodies change over the years, and as we gain experience. An important aspect of a congruent representation of the body in the brain is the visual perspective in which we are able to directly view our own body. There is a clear separation of the cortical networks involved in seeing our own body and that of another person. For the projects presented in my dissertation, I used an experimental design in which participants were required to make a multisensory temporal asynchrony discrimination after self-generated movements. I measured sensitivity for visual delay detection between the movement (proprioceptive, efferent and afferent information) and the visual image of that movement under differing visual, proprioceptive, and vestibular conditions. The self-advantage is a signature of body ownership and is characterized by a significantly lower threshold for delay detection for views of the body that are considered self compared to those that are regarded as other. Overall, the results from the collection of studies suggest that the tolerance for temporally matching visual, proprioceptive and efferent copy information that informs about the perceived position of body parts depends on: whether one is viewing ones own body or someone elses; the perspective in which the body is viewed; the dominant hand; and the reliability of vestibular cues which help us situate our body in space. Further, the self-advantage provides a robust measure of body ownership. The experiments provide a window on and support for the malleable nature of the representation of the body in the brain

Brain Networks for Integrative Rhythm Formation

Performance of externally paced rhythmic movements requires brain and behavioral integration of sensory stimuli with motor commands. The underlying brain mechanisms to elaborate beat-synchronized rhythm and polyrhythms that musicians readily perform may differ. Given known roles in perceiving time and repetitive movements, we hypothesized that basal ganglia and cerebellar structures would have greater activation for polyrhythms than for on-the-beat rhythms.Using functional MRI methods, we investigated brain networks for performing rhythmic movements paced by auditory cues. Musically trained participants performed rhythmic movements at 2 and 3 Hz either at a 1:1 on-the-beat or with a 3:2 or a 2:3 stimulus-movement structure. Due to their prior musical experience, participants performed the 3:2 or 2:3 rhythmic movements automatically. Both the isorhythmic 1:1 and the polyrhythmic 3:2 or 2:3 movements yielded the expected activation in contralateral primary motor cortex and related motor areas and ipsilateral cerebellum. Direct comparison of functional MRI signals obtained during 3:2 or 2:3 and on-the-beat rhythms indicated activation differences bilaterally in the supplementary motor area, ipsilaterally in the supramarginal gyrus and caudate-putamen and contralaterally in the cerebellum.The activated brain areas suggest the existence of an interconnected brain network specific for complex sensory-motor rhythmic integration that might have specificity for elaboration of musical abilities

Active disturbance cancellation in nonlinear dynamical systems using neural networks

A proposal for the use of a time delay CMAC neural network for disturbance cancellation in nonlinear dynamical systems is presented. Appropriate modifications to the CMAC training algorithm are derived which allow convergent adaptation for a variety of secondary signal paths. Analytical bounds on the maximum learning gain are presented which guarantee convergence of the algorithm and provide insight into the necessary reduction in learning gain as a function of the system parameters. Effectiveness of the algorithm is evaluated through mathematical analysis, simulation studies, and experimental application of the technique on an acoustic duct laboratory model

A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

In recent years, there has been a dramatic increase in the use of unmanned aerial vehicles (UAVs), particularly for small UAVs, due to their affordable prices, ease of availability, and ease of operability. Existing and future applications of UAVs include remote surveillance and monitoring, relief operations, package delivery, and communication backhaul infrastructure. Additionally, UAVs are envisioned as an important component of 5G wireless technology and beyond. The unique application scenarios for UAVs necessitate accurate air-to-ground (AG) propagation channel models for designing and evaluating UAV communication links for control/non-payload as well as payload data transmissions. These AG propagation models have not been investigated in detail when compared to terrestrial propagation models. In this paper, a comprehensive survey is provided on available AG channel measurement campaigns, large and small scale fading channel models, their limitations, and future research directions for UAV communication scenarios