Search

To further develop a low-power, low-cost optical motion detector for use with traffic detection under dark and daylight conditions, we have developed and verified a procedure to use a near-sensor image processing programmable 2-D optical sensor in a "1-D mode" to achieve the effect of using a cylindrical lens, thus improving the angle-of-view (AOV), the sensitivity, and usefulness of the sensor. Using an existing 256 x 256 element sensor in an innovative way, the AOV was increased from 0.4. to 21.3. in the vertical direction while also improving the sensitivity. The details of the sensor hardware architecture are described in detail and pseudo-code for programming the sensor is discussed. The results were used to demonstrate the extraction of local extreme points used for time-to-impact calculations to estimate the speed of an approaching vehicle.

We present a method suitable for a time-to-impact sensor. Inspired by the seemingly "low" complexity of small insects, we propose a new approach to optical flow estimation that is the key component in time-to-impact estimation. The approach is based on measuring time instead of the apparent motion of points in the image plane. The specific properties of the motion field in the time-to-impact application are used, such as measuring only along a one-dimensional (1-D) line and using simple feature points, which are tracked from frame to frame. The method lends itself readily to be implemented in a parallel processor with an analog front-end. Such a processing concept [near-sensor image processing (NSIP)] was described for the first time in 1983. In this device, an optical sensor array and a low-level processing unit are tightly integrated into a hybrid analog-digital device. The high dynamic range, which is a key feature of NSIP, is used to extract the feature points. The output from the device consists of a few parameters, which will give the time-to-impact as well as possible transversal speed for off-centered viewing. Performance and complexity aspects of the implementation are discussed, indicating that time-to-impact data can be achieved at a rate of 10 kHz with todays technology.

SummaryWe have developed an assay where the potency of retinoids in retinoic acid receptor (RAR) mediated transcriptional activation can be rapidly evaluated. In this assay hRAR-[alpha], hRAR-[beta] and hRAR-[gamma] were expressed in CV-1 cells together with a reporter gene containing a retinoic acid responsive element (TRE3-tk-CAT). Concentrations required to obtain half-maximum induction (ED50 of CAT-activity were determined for several retinoids, e.g., all-trans-retinoic acid (RA), 13-cis-retinoic acid (13-cis-RA), arotinoid acid (TTNPB) and m-carboxy-arotinoid acid (m-carboxy-TTNPB, an inactive arotinoid analog). The ED50 values for RA decreased in the order of RAR-[alpha] (24 nM) > RAR-[beta] (4.0 nM) > RAR-[gamma] (1.3 nM), while the ED50 values for TTNPB and 13-cis-RA decreased in the order of RAR-[alpha] (6.5 nM, 190 nM) > RAR-[gamma] (2.3 nM, 140 nM) > RAR-[beta] (0.6 nM, 43 nM), respectively. No significant inductions were obtained when cells were treated with m-carboxy-TTNPB, even at 10 [mu]M concentrations. The fold induction of CAT-activity for all compounds tested decreased in the order of RAR-[alpha] > RAR-[beta] > RAR-[gamma].