We have developed a fundamentally new type of cytometer to track the statistics of dynamic molecular interactions in
hundreds of individual live cells within a single experiment. This entirely new high-throughput experimental system,
which we have named Cyto•IQ, reports statistical, rather than image-based data for a large cellular population. Like a
flow cytometer, Cyto•IQ rapidly measures several fluorescent probes in a large population of cells to yield a reduced
statistical model that is matched to the experimental goals set by the user. However, Cyto•IQ moves beyond flow
cytometry by tracking multiple probes in individual cells over time. Using adaptive learning algorithms, we process data
in real time to maximize the convergence of the statistical model parameter estimators.
Software controlling Cyto•IQ integrates existing open source applications to interface hardware components, process
images, and adapt the data acquisition strategy based on previously acquired data. These innovations allow the study of
larger populations of cells, and molecular interactions with more complex dynamics, than is possible with traditional
microscope-based approaches. Cyto•IQ supports research to characterize the noisy dynamics of molecular interactions
controlling biological processes.
Results of two lidar measurement campaigns are presented, HOLO-1 (Utah, March 1999) and HOLO-2 (New Hampshire, June 1999). These tests demonstrate the ability of lidars utilizing holographic optical elements (HOEs) to determine tropospheric wind velocity and direction at cloud altitude. Several instruments were employed. HOLO-1 used the 1.064 mm transmission-HOE lidar (HARLIE, Goddard Space Flight Center), a zenith-staring 532 nm lidar (AROL-2, Utah State University), and a wide-field video camera (SkyCam) for imagery of clouds overhead. HOLO-2 included these instruments plus the 532 nm reflection-HOE lidar (PHASERS, St. Anselm College). HARLIE and PHASERS scan the sky at constant cone angles of 45° and 42° from normal, respectively. The progress of clouds and entire cloud fields across the sky is tracked by the repetitive conical scans of the HOE lidars. AROL-2 provides the altitude information enabling the SkyCam cloud images to be analyzed for independent data on cloud motion. Data from the HOE lidars are reduced by means of correlations, visualization by animation techniques, and kinematic diagrams of cloud feature motion. Excellent agreement is observed between the HOE lidar results and those obtained with video imagery and lidar ranging.
The design of an unusually compact and rugged backscatter lidar system is described in detail. This lidar system, called AROL- 2, was designed for routine monitoring of the boundary layer, tropospheric aerosols, and clouds. In order to support the maximum possible range of observations with minimum investment of labor, the system was specifically designed to be mobile, rugged, and easy to set up and deploy. The lidar system is housed in a weatherproof enclosure, in order to allow operation at sites without sophisticated laboratory facilities. In order to provide maximum flexibiliity and sensitivity in a relatively small package, the lidar system is equipped with both analog and photon counting channels, with two polarization channels to allow for quantitative measurementsof depolarization behavior. Substantial effort has been expended to produce a lidar that is flexible, easy to use, and robust in the field environment.
The transition into 'real world' applications, and the accompanying development of commercial business opportunities and ventures, is an important part of the technology development process. We discuss the present state of lidar commercialization and deployment into these applications. We then go on to discuss the ways in which the research community can (and we believe should) affect this technology adoption process.
We have designed a very compact, low cost lidar system designed for profiling of aerosols in the planetary boundary layer. Our design emphasizes portability, reliability, ease-of-use, and the lowest possible cost. Our goal is an instrument which can provide easy and reliable characterization of the boundary layer for users in operational meteorology or air quality management. The lidar transmitter is a diode laser array. As compared with more conventional laser transmitters, the diode array offers overwhelming advantages in compactness, reliability, and cost. The emission wavelength of the AlGaAs diode array is well matched to the peak sensitivity of silicon avalanche photodiodes. The transmitter and receiver are polarization multiplexed through a common aperture. A relatively large (37 cm) optical aperture compensates for the low transmitter peak power. Since the main mission of this particular lidar is measurement in and around major urban areas where aerosol loadings are generally high, the modest sensitivity is not a severe limitation. The transmitter beam is eye- safe at all ranges. Control and data acquisition are managed by a portable computer. To demonstrate the capabilities of the design, we show simulated results under a wide variety of atmospheric conditions.
A self-contained mobile differential absorption lidar (DIAL) system intended for measuring SO2 and NO2 concentrations from stationary combustion sources has been completed for enforcement use. The system uses tunable Ti:sapphire laser technology, with nonlinear conversion to the blue and UV absorption wavelengths. Separate tunable laser oscillators at slightly offset wavelengths are pumped on alternate pulses of a 20 Hz doubled Nd:YAG pump laser; the outputs are amplified in a common amplifier, doubled or tripled, and transmitted toward a target region via a two-mirror beam director. Scattered atmospheric returns are collected in a 0.27-m-diameter telescope, detected with a filtered photomultiplier, and digitized and stored for analysis. Extensive software-based control and display windows are provided for operator interaction with the system. The DIAL system is built into a small motor coach. Gasoline- powered electrical generation, laser cooling, and air conditioning services are present. Separate computers are provided for simultaneous data collection and data analysis activities, with shared data base access. A laser printer supplies hardcopy output. The system includes the capability for automatic data collection at a series of scanner angles, and computer processing to present results in a variety of formats. Plumes from coal-fired and mixed-fuel-fired combusters have been examined for NO2 and SO2 content. Noise levels of a few parts per million are reached with averaging times of less than one minute.
A novel computer model of an injection-seeded pulsed CO2 laser is used to predict the intrapulse frequency chirp as a function of laser resonator and gain medium parameters. A new mechanism for causing intrapulse frequency sweeping is predicted. It is found that nonuniform and time-varying gain saturation changes the transverse distribution of the intracavity electric field during the laser pulse, which leads to a change in the oscillator frequency. This mechanism is predicted to be much more pronounced in low-magnification graded-reflectivity unstable resonators as compared to low-Fresnel-number stable resonators. It is also shown that to obtain quantitative estimates of chirp in large aperture unstable resonators lasers, it is necessary to couple the intracavity electric field with realistic laser kinetics and index-changing mechanisms.
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