An improved 2D optical flow sensor for motion segmentation

A functional focal-plane implementation of a 2D optical flow system is presented that detects an preserves motion discontinuities. The system is composed of two different network layers of analog computational units arranged in a retinotopical order. The units in the first layer (the optical flow network) estimate the local optical flow field in two visual dimensions, where the strength of their nearest-neighbor connections determines the amount of motion integration. Whereas in an earlier implementation \cite{Stocker_Douglas99} the connection strength was set constant in the complete image space, it is now \emph{dynamically and locally} controlled by the second network layer (the motion discontinuities network) that is recurrently connected to the optical flow network. The connection strengths in the optical flow network are modulated such that visual motion integration is ideally only facilitated within image areas that are likely to represent common motion sources. Results of an experimental aVLSI chip illustrate the potential of the approach and its functionality under real-world conditions

Integrated 2-D Optical Flow Sensor

I present a new focal-plane analog VLSI sensor that estimates optical flow in two visual dimensions. The chip significantly improves previous approaches both with respect to the applied model of optical flow estimation as well as the actual hardware implementation. Its distributed computational architecture consists of an array of locally connected motion units that collectively solve for the unique optimal optical flow estimate. The novel gradient-based motion model assumes visual motion to be translational, smooth and biased. The model guarantees that the estimation problem is computationally well-posed regardless of the visual input. Model parameters can be globally adjusted, leading to a rich output behavior. Varying the smoothness strength, for example, can provide a continuous spectrum of motion estimates, ranging from normal to global optical flow. Unlike approaches that rely on the explicit matching of brightness edges in space or time, the applied gradient-based model assures spatiotemporal continuity on visual information. The non-linear coupling of the individual motion units improves the resulting optical flow estimate because it reduces spatial smoothing across large velocity differences. Extended measurements of a 30x30 array prototype sensor under real-world conditions demonstrate the validity of the model and the robustness and functionality of the implementation

Compact Integrated Transconductance Amplifier Circuit for Temporal Differentiation

A compact integrated CMOS circuit for temporal differentiation is presented. It consists of a high-gain inverting amplifier, an active non-linear transconductance and a capacitor and requires only 4 transistors in its minimal configuration.The circuit provides two rectified current outputs that are proportional to the temporal derivative of the input voltage signal. Besides the compactness of its design, the presented circuit is not dependent on the DC-value of the input signal, as compared with known integrated differentiator circuits. Measured chip results show that the circuit operates on a large input frequency range for which it provides nearideal temporal differentiation. The circuit is particularly suited for focal-plane implementations of gradient-based visual motion systems

Computation of Smooth Optical Flow in a Feedback Connected Analog Network

In 1986, Tanner and Mead \cite{Tanner_Mead86} implemented an interesting constraint satisfaction circuit for global motion sensing in aVLSI. We report here a new and improved aVLSI implementation that provides smooth optical flow as well as global motion in a two dimensional visual field. The computation of optical flow is an ill-posed problem, which expresses itself as the aperture problem. However, the optical flow can be estimated by the use of regularization methods, in which additional constraints are introduced in terms of a global energy functional that must be minimized. We show how the algorithmic constraints of Horn and Schunck \cite{Horn_Schunck81} on computing smooth optical flow can be mapped onto the physical constraints of an equivalent electronic network

Choice-dependent Perceptual Biases

The perceived motion direction of a dynamic random dot stimulus is systematically biased when preceded by a motion discrimination task (Jazayeri and Movshon, 2007). The biases were originally thought to occur because subjects mistakenly reuse the neural read-out optimized for the discrimination task when forming the percept (Fig.1a, Task-dependent model). In a series of experiments, we demonstrated that this explanation is incorrect and that the biases actually result from the conditioning of the percept on the preceding discrimination judgment (Fig1.b, Choice-dependent model). Experiment 1 was aimed at replicating the biases for an orientation stimulus. Subjects first indicated whether the stimulus orientation was clockwise (CW) or counter-clockwise (CCW) of a randomly chosen reference orientation. Subsequently they had to reproduce the stimulus orientation (Fig1.c). Experiment 2 was identical to Experiment 1 except that the total range of the stimulus were shown at the beginning of each trial. Experiment 3 was identical to Experiment 2 except that subjects were given the correct answer of the discrimination judgment (CW/CCW) and they instead performed an irrelevant decision task. Subjects’ estimates were systematically biased away from the decision boundary in Exp. 1(Fig.1 c). Similar biases occurred in Exp. 2 and 3. Because the task-dependent model is insensitive to the stimulus range and is contingent on subjects performing a discrimination, it cannot capture the shift of bias curves in Exp. 2 and in Exp. 3. In contrast, the choice-dependent model predicts all those features in the data assuming that subjects learned the narrower prior range and conditioned their percepts on the given decision outcome

The City by the Pool

This volume offers a new and up-to-date synthesis of Lincoln's long history as a major city and regional capital, from prehistory to 1945. The 'City by the Pool' was a major religious centre long before the Roman invasion and from bronze-age shamans to early Baptists people have always been attracted here for spiritual as well as mundane purposes. The authors argue for the presence of a major ritual causeway of the late Bronze and Iron Age and outline the extent to which ritual monuments also contributed to the character of Roman Lincoln. This book is based on more than a hundred publicly-funded excavations and building surveys undertaken between 1945 and 2000. It surveys all aspects of city life, from housing and fortifications to the water supply and rubbish disposal. It includes a CD Rom with a Geographic Information System (GIS) and a relational data-base known as LARA (the Lincoln Archaeological Research Assessment)

The City by the Pool

This volume offers a new and up-to-date synthesis of Lincoln's long history as a major city and regional capital, from prehistory to 1945. The 'City by the Pool' was a major religious centre long before the Roman invasion and from bronze-age shamans to early Baptists people have always been attracted here for spiritual as well as mundane purposes. The authors argue for the presence of a major ritual causeway of the late Bronze and Iron Age and outline the extent to which ritual monuments also contributed to the character of Roman Lincoln. This book is based on more than a hundred publicly-funded excavations and building surveys undertaken between 1945 and 2000. It surveys all aspects of city life, from housing and fortifications to the water supply and rubbish disposal. It includes a CD Rom with a Geographic Information System (GIS) and a relational data-base known as LARA (the Lincoln Archaeological Research Assessment)

Ageing well with diabetes: A workshop to co‐design research recommendations for improving the diabetes care of older people

Aims:To identify key research questions where answers could improve care for older people living with diabetes (PLWD), and provide detailed recommendations for researchers and research funders on how best to address them.Methods:A series of online research workshops were conducted, bringing together a range of PLWD and an acknowledged group of academic and clinical experts in their diabetes care to identify areas for future research. Throughout the pre-workshop phase, during each workshop, and in manuscript preparation and editing, PLWD played an active and dynamic role in discussions as part of both an iterative and narrative process.Results:The following key questions in this field were identified, and research recommendations for each were developed:How can we improve our understanding of the characteristics of older people living with diabetes (PLWD) and their outcomes, and can this deliver better person-centred care?How are services to care for older PLWD currently delivered, both for their diabetes and other conditions? How can we optimise and streamline the process and ensure everyone gets the best care, tailored to their individual needs?What tools might be used to evaluate the level of understanding of diabetes in the older population amongst non-specialist Healthcare Professionals (HCPs)?How can virtual experts or centres most effectively provide access to specialist multi-disciplinary team (MDT) expertise for older PLWD and the HCPs caring for them?Is a combination of exercise and a nutrition-dense, high protein diet effective in the prevention of the adverse effects of type 2 diabetes and deterioration in frailty, and how might this be delivered in a way which is acceptable to people with type 2 diabetes?How might we best use continuous glucose monitoring (CGM) in older people and, for those who require support, how should the data be shared?How can older PLWD be better empowered to manage their diabetes in their own home, particularly when living with additional long-term conditions?What are the benefits of models of peer support for older PLWD, both when living independently and when in care?Conclusions:This paper outlines recommendations supported by PLWD through which new research could improve their diabetes care and calls on the research community and funders to address them in future research programmes and strategies