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The intensity and duration of contrast effect within the left ventricular cavity after an intravenous bolus of Levovist Injection were observed with both harmonic and fundamental imaging in nine patients with known or suspected coronary artery disease. Contrast intensity was assessed by a qualitative grading system (0, none; 1, weak; 2, moderate; 3, good) and by videodensitometric analysis of pixel intensity. Duration of left ventricular contrast effect was determined by measuring time from the initial visual appearance of contrast agent to its disappearance. The mean increase in pixel intensity within the left ventricular cavity from precontrast to peak contrast was significantly greater for second harmonic than for fundamental imaging (25.5 vs 7.1; P < 0.012). The mean contrast intensity qualitative score with harmonic imaging was higher (2.6 ± 0.73 vs 1.2 ± 0.44; P < 0.01) and the duration of contrast effect was longer (242 ± 131 s vs 53 ± 33 s; P < 0.004). Second harmonic imaging significantly enhanced contrast intensity and prolonged visible duration of contrast effect after a peripheral venous injection of Levovist.

Full field hard X-ray microscopy has recently been developed utilizing synchrotron light, enabling absorption and phase contrast imaging with a spatial resolution of 50 -100 nm. This technique has allowed us to image bone tissue at the nanoscale level, viewing the substructure of mineralized collagen fibers. Thin sections of tissue (5 and 50 mum thick) from the L3 vertebrae of Beagles and mineralizing MC3T3-E1 mouse osteoblasts were imaged at beamline 01B1 at the National Synchrotron Radiation Research Center (Hsinchu, Taiwan). Collagen fiber orientation was observed in the lamellar structure of an osteon. Mineralizing osteoblasts were found to produce disordered mineralized nodules with varying density and structure.

The dynamic estimation of large-scale stochastic image sequences, as frequently encountered in remote sensing, is important in a variety of scientific applications. However, the size of such images makes conventional dynamic estimation methods, for example, the Kalman and related filters, impractical. In this paper, we present an approach that emulates the Kalman filter, but with considerably reduced computational and storage requirements. Our approach is illustrated in the context of a 512 x 512 image sequence of ocean surface temperature. The static estimation step, the primary contribution here, uses a mixture of stationary models to accurately mimic the effect of a nonstationary prior, simplifying both computational complexity and modeling. Our approach provides an efficient, stable, positive-definite model which is consistent with the given correlation structure. Thus, the methods of this paper may find application in modeling and single-frame estimation.

The authors analyze both conventional and long-term integration performance in sea clutter using the spatial variation clutter model, taking into account applicable effects of partial overlapping due to integration along multiple paths. It is demonstrated that conventional integration performance is greatly diminished in spatially varying clutter because of lack of ability to perform spatial smoothing. It is also demonstrated that long-term integration across resolvable areas provides for spatial smoothing, significantly enhancing detection performance. Finally, it is shown that for a shipboard radar against sea-skimming missiles, long-term integration provides around 10-dB increase in detection sensitivity over conventional cumulative detection, allowing detection of -30 dBsm sea-skimmers with 90% probability at 10 km range in sea state 4. >

Sea clutter echoes are well described using the spatial variation model. In this mode, the local temporal fluctuation within each area resolvable by the radar has a local mean that varies independently across resolvable areas. A much larger global area, having nearly the same grazing angle, defines the region in which the local mean varies spatially. This spatial variation model is used to determine radar detection performance in sea clutter of conventional noncoherent integration. The performance suffers significantly because of the additional fluctuation caused by the spatial variation. The degradation can be significant-as much as 20 dB or more over the homogeneous clutter case. The reduced performance is explained by the lack of smoothing the spatial variation. A remedy is offered based upon long-term integration over many resolvable areas as the target moves radially. The resultant smoothing, before presentation to a detection threshold, reduces the effect of the spatial variation. >

We propose a low-power, /spl sim/$3 k CW radar system, based on the latest commercial MMIC technology, to detect and estimate the trajectory of small-caliber projectiles. Using the Doppler histories from three CW /spl sim/1 Watt transceivers spaced /spl lsim/1 m apart, the system is shown to estimate trajectory angle to /spl plusmn/1/spl deg/ for bullets that pass within 10 m. The system can be carried by personnel or mounted on a vehicle for point defense. Multiple systems along a perimeter provide area protection. Proof of concept could be accomplished within one year.

There is a substantial signal-processing challenge associated with large-scale (especially global-scale) remote-sensing problems: solving the statistical inverse problem (i.e. deducing the properties of the sensed field from measurements) by brute force, that is by covariance matrix inversion, is completely impractical for fields involving millions of pixels. This paper reports on the ongoing development of an alternative technique, in which the statistical problem is modeled on a multiscale tree, applied to estimating sea-surface temperature (SST) based on infrared radiance observations from the along-track scanning radiometers (ATSRs).

The problem of data fusion, the merging of data taken by different sensors, becomes ever more relevant with the launch of each new remote-sensing platform. One example of considerable current interest in the climate change community is the production of an improved sea surface temperature (SST) map. In particular, two state-of-the-art instruments - the Along Track Scanning Radiometer (ATSR) and AVHRR - share complementary features: ATSR allows excellent cloud discrimination and atmospheric correction based on its dual-view scanning geometry, but observes only narrow swaths of ocean; AVHRR suffers from low-wavenumber atmospheric distortions and cloud contamination, but has extensive global coverage. The authors propose a methodology for combining ocean skin temperatures from the ATSR and AVHRR instruments to produce a continuous analysis at one-sixth degree spatial and three-day temporal resolutions, together with reliable error estimates, from the fusion of multiple datasets with arbitrary sampling characteristics, resulting in estimated temperatures which unite the precision of ATSR with the superior coverage afforded by AVHRR.

A risk-based assessment of the overall waste volume versus double-shell tank storage capacity was conducted to develop fallback positions for projections where the waste volume was at a high risk of exceeding capacity. This study was initiated to provide that assessment. A working simulation model was the primary deliverable of this study. The model validates the approach and demonstrates that simulation analysis can provide a method of tracking uncertainties in available data, assessing probabilities, and serves as a tool to be used by management to determine the consequences of various off-normal occurrences.

A structure has been developed for tracking maneuvering undersea targets when the observations are passive. Inherent in this problem is the ability to smooth the original measurements before the highly nonlinear transformations to range, so that the range estimate will be less biased. Unlike other tracking techniques, the approach offered is to break up the problem into two stages, before and after the range transformation. It is shown by simulation that the structure substantially reduces the range bias while closely following maneuvering sources at varying distances. The exhibited bias reduction and stability is a clear improvement over previous approaches to this particular application. >

Long-term integration is defined as integration, perhaps interrupted, over time periods long enough for targets to move through volumes in space resolvable by the radar. Because the motion of the target is unknown prior to detection, long-term integration must be performed along multiple paths representing plausible target paths. The geometry of such a set of integration paths affects detection performance in several ways. The simplest implementation of long-term integration, using constant radial velocity paths, is investigated. The effects of path geometry on detection is quantified and optimized for a target whose motion is nearly radial but otherwise unknown. >

This paper addresses the dynamic estimation of the ocean surface temperature based on data from the Along-Track Scanning Radiometer (ATSR) for large (512/spl times/512) fields. For such huge problems, the conventional dynamic estimation tool (the Kalman filter) is not directly applicable, instead, we develop a recursive estimation algorithm that emulates the Kalman filter. Our approach uses a multiscale estimation algorithm for the update step, and makes simplifying assumptions about the surface dynamics leading to a computationally efficient prediction step.