The walk-through metal-detection portal is a paradigm of non-intrusive passenger screening in aviation security. Modern explosive detection portals based on this paradigm will soon appear in airports. This paper suggests that the airborne trace detection technology developed for that purpose can also be adapted to human chemical and biological contamination. The waste heat of the human body produces a rising warm-air sheath of 50-80 liters/sec known as the human thermal plume. Contained within this plume are hundreds of bioeffluents from perspiration and breath, and millions of skin flakes. Since early medicine, the airborne human scent was used in the diagnosis of disease. Recent examples also include toxicity and substance abuse, but this approach has never been quantified. The appearance of new bioeffluents or subtle changes in the steady-state may signal the onset of a chemical/biological attack. Portal sampling of the human thermal plume is suggested, followed by a pre-concentration step and the detection of the attacking agent or the early human response. The ability to detect nanogram levels of explosive trace contamination this way was already demonstrated. Key advantages of the portal approach are its rapidity and non-intrusiveness, and the advantage that it does not require the traditional bodily fluid or tissue sampling.
Application of a novel transform operator, the Sticklet transform, to the quantitative estimation of trace chemicals in industrial effluent plumes is reported. The sticklet transform si a superset of the well-known derivative operator and the Haar wavelet, and is characterized by independently adjustable lobe width and separation. Computer simulations demonstrate that we can make accurate and robust concentration estimates of multiple chemical species in industrial effluent plumes in the presence of strong clutter background, interferent chemicals and random noise. In this paper we address the application of the sticklet transform in estimating chemical concentrations in the effluent plumes in the presence of atmospheric transmission effects. We show that this transform retains the ability to yield accurate estimates using on-plume / off-plume measurements that represenst atmospheric differentials up to 10% of the full atmospheric attenuation.
Although the Chemical Weapons Convention prohibits the development, production, stockpiling, and use of chemical warfare agents (CWAs), the use of these agents persists due to their low cost, simplicity in manufacturing and ease of deployment. These attributes make these weapons especially attractive to low technology countries and terrorists. The military and the public at large require portable, fast, sensitive, and accurate analyzers to provide early warning of the use of chemical weapons. Traditional laboratory analyzers such as the combination of gas chromatography and mass spectroscopy, although sensitive and accurate, are large and require up to an hour per analysis. New, chemical specific analyzers, such as immunoassays and molecular recognition sensors, are portable, fast, and sensitive, but are plagued by false-positives (response to interferents). To overcome these limitations, we have been investigating the potential of surface-enhanced Raman spectroscopy (SERS) to identify and quantify chemical warfare agents in either the gas or liquid phase. The approach is based on the extreme sensitivity of SERS demonstrated by single molecule detection, a new SERS material that we have developed to allow reproducible and reversible measurements, and the molecular specific information provided by Raman spectroscopy. Here we present SER spectra of chemical agent simulants in both the liquid and gas phase, as well as CWA hydrolysis phase.
Our earlier study described an approach for estimating the path-integrated concentration, CL, of a set of vapor materials using time series data from topographic backscatter lidar with frequency-agile lasers. That methodology assumed the availability of background data samples collected before the release of the vapors of interest to estimate statistical parameters such as the mean topographic backscatter return and the transmitter energy mean and variance as a function of wavelength. The background data were then used in an extended Kalman filter approach for estimating the CL components as a function of time. That approach worked well for data that showed negligible drift in the mean parameters over the data collection time. In practice, however, the transmitter energy and background return can drift, producing substantial bias in the estimates. In this paper we generalize the approach to a more complete state model that includes the mean transmitter energy and background return in addition to the CL vapor set. This generalization allows the algorithm to track slow drift in those parameters and provides generally improved estimates. Results of the new algorithm are compared with those of a two-wavelength classical DIAL estimator on synthetic and field test data.
The WILDCAT sensor was developed to provide chemical detection and identification at large standoff ranges on the order of 20 km for concentration-path length product measurements and 5 km for range-resolved measurements. The transmitter is a wavelength agile CO2 laser with output energy of 1 J/pulse at a repetition rate of 100 Hz. The laser wavelength can be shifted by a two-stage second harmonic generator and optical parametric oscillator to prove chemical absorption features outside the normal laser emission bands. The receiver is composed of a 60 cm dia. Cassegrain telescope and two-element HgCdTe detector that are integrated into a gimbal system for full hemispherical scanning. The laser/optical table and gimbal/telescope subsystems are connected by a rigid truss and all components are integrated into a transportable field test station. The data acquisition system is composed of 12 bit, 125 MHz analog-digital converters and a digital signal processor. Algorithms allow for real-time data processing and display of chemical concentration maps. All key transmitter and receiver components are capable of further development for compact, standalone sensors that can operate from fixed sites or mobile platforms, including aircraft, ships, and ground vehicles.
The US Army Chemical Biological Center and Raytheon Electronic Systems are developing a lightweight, compact sensor, known as the Standoff Handheld Real-time Early Warning Detector (SHREWD), for detection of airborne chemicals at ranges of 3-5 km by differential absorption lidar for manportable applications and for vehicles where sensor size and weight are restricted. Engineering analysis shows that the final deployable sensor size and weight would be 0.9 cu gt and 35 lb, respectively. The fieldable breadboard sensor now under development in phase 1 of the program is composed of independent transmitter and receiver sections mounted on either side of a single, 20 in. By 24 in. Optical table held vertically on a tripod. The transmitter is composed of an air-cooled Nd:YAG pump laser and a robust, two-stage OPO that shifts the pump laser output to the 8-12 micrometers band. The pump laser emits 20 mJ pulses at a repetition rate of 300 Hz in a 1.2 time diffraction limited beam; and the OPO overall conversion efficiency is 1.2% resulting in an output pulse energy of 240 (mu) J. The sensor receiver is based on a 12 cm diameter, off-axis paraboloid mirror and cryo-engine-cooled HgCdTe detector. Data acquisition is performed by 8 bit, analog- digital converters with 0.5 ns resolution and data processing/display are performed in real time.
Diode-pumped, tunable Cr:LiSAF lasers are well suited for airborne water vapor differential absorption lidar application. Three types of diode-pumped, tunable, narrow- linewidth, injection seeded, Q-switched Cr:LiSAF lasers for high resolution atmosheric water vapor DIAL measurements in the wavelength range of 810-830 nm have been developed and investigated. By using a total internal reflection laser resonator configuration, efficient coupling of pump radiation from large diode arrays is achieved as also the ability to limit the temperature rise in the LiSAF crystal at high pump powers. The first is a high-energy Cr:LiSAF laser producing up to 25 mJ/pulse at 816 nm with a repetition rate of 1-10 Hz. A DFB diode laser locked to a water vapor absorption line using a photo-acoustic cell was employed to injection seed and tune the slave Cr:LiSAF laser. High spectral purity (<99%) and wavelength stability of 0.08 pm over a period of 10 hours were demonstrated. The second Cr:LiSAF laser is designed to operate at 100 Hz while producing up to 10 mJ/pulse with a much lesser pump power. The reduction in size and weight of this laser coupled with the increased average power leads to significant improvement in the DIAL performance over the first laser. The third diode-pumped Cr:LiSAF laser is an ultra compact laser producing up to 0.1 mJ/pulse at 1000 Hz. This laser is suitable for measuring water vapor profiles in the lower troposhere (3 to 5 km). The input-output and spectral performance of these lasers are presented.
Remote detection of biological warfare agents (BWA) is crucial for providing early warning to ensure maximum survivability of personnel in the battlefield and other sensitive areas. Although the current generation of stand- off aerosol and fluorescence lidars have demonstrated stand- off detection and identification of BWA, their large size and cost make them difficult for field use. We have introduced a new eye-safe portable digital lidar (PDL) technique based on digital detection that achieves orders of magnitude reduction in the size, cost and complexity over the conventional lidar, while providing an equal or better sensitivity and range. Excellent performance has been obtained with two of our PDL sensors during two bio-aerosol measurement campaigns carried out at Dugway Proving Grounds. In the JFT 4.5 (Oct 98) tests, high aerosol sensitivity of 300 ppl of biosimulant particles at up to 3 km was demonstrated with an eye-safe wavelength (523nm) aerosol micro PDL that utilized a 8 inch telescope, <10(mu) J/pulse energy at 2.5kHz, photon counting digital detection and 2 sec averaging. For the JBREWS DFT (June 99) tests an eye-safe two wavelengths (523nm and 1.047mum) horizontally scanned, aerosol micro PDL with the same 8 inch telescope was utilized. With this lidar, high sensitivity, preliminary differentiation between natural and unusual clouds, and the ability to track the aerosol cloud location, their wind speed and direction were also demonstrated. Lidar simulations of both PDL and conventional analog detection have been performed. Based on these model calculations and experimental results an analysis and comparison of the inherent capabilities of two types of systems is given.
A passive infrared (IR) sensor of chemical weapon agents (CWA) is being developed using a new approach (patent pending) for differential absorption radiometry (DAR). The sensor can be packaged as a handheld device, unattended sensor, remote imager and more. An agent is detected by its IR absorption (or emission) viewed through a bandpass filter centered at one of its strong spectral lines. A second detector is equipped with a filter centered at a frequency that was optimized to provide near perfect correction for background absorption by at least one atmospheric species, e.g., water vapor. The net absorption by the CWA is obtained by subtracting the reference signal of the background detector from that of the CWA-dedicated detector and normalized by dividing it by the total signal. A simple electronic circuit provides normalized differences to within 1:106. This new approach replaces spectral scanning wiht detection at strong pre-selected spectral bands of chosen species and provides near perfect correction of absorption by pre-selected background species. The DAR is more efficient and thus more sensitive than alternative passive remote sensors. Specificity can be enhanced by integrating multiple DARs into a a single system using detector-filter arrays.
The sensitivity of imaging, hyperspectral, passive remote sensors in the long-wavelength infrared (LWIR) spectral region is currently limited by the ability to achieve an accurate, time-invariant, pixel-to-pixel calibration of the elements composing the Focal Plane Array (FPA). Pursuing conventional techniques to improve the accuracy of the calibration will always be limited by the trade-off between the time required to collect calibration data of improved precision and the drift in the pixel response that occurs on a timescale comparable to the calibration time. This paper will present the results from a study of a method to circumvent these problems. Improvements in detection capability can be realized by applying a quick, repetitive dither of the field of view (FOV) of the imager (by a small angular amount), so that radiance/spectral differences between individual target areas can be measured by a single FPA pixel. By performing this difference measurement repetitively both residual differences in the pixel-to-pixel calibration and 1/f detector drift noise can effectively be eliminated. In addition, variations in the atmosphere and target scene caused by the motion of the sensor platform will cause signal drifts that this technique would not be able to remove. This method allows improvements in sensitivity that could potentially scale as the square root of the observation time.
The aim of this paper is to study a new predictive impact on Cancer Formation constituted by the Solar Neutrinos Flux. Billions of Solar Neutrinos particles cross the human body each second without our feeling anything, and this phenomenon can give a valid reply to three basic questions on Cancer Formation such as: 1. Why Cancer appears at all types of cells 2. Why Cancer appears at all ages 3. Why Cancer appears in all segments of the human body It is experimentally proved that Solar Neutrinos interact with an atom of Chlorine 37, converting this stable atom in an unstable radioactive atom as Argon 37, and Molybdenum, is converted under Solar Neutrinos Flux in a radioactive atom of Technitium, Gallium 71 is converted into an unstable radioactive atom of Germanium, and I think that the list is not closed. It is well known that Chlorine 37 atoms and others are found in each cell in the human body assuring the vital metabolism of all our cells and astrophysicists experiments related to this subject of Chlorine 37 have a crucial importance for general medical sciences also especially in the field of Cancer diseases. Today, for the first time in the world, studies in Cancer Formation under Neutrinos Effects crossing the human body, can be made as soon as possible under an International and an Interdisciplinary Cooperation with special equipment such as the Biocassette-Telebiological-Microscopy (BTM) and its versatility, presented in this paper with some preliminary experiments. The purpose of this BTM system is to be able to see and follow in a continuous and dynamic form by Video-TV-Recorder system any changes or transformations of a normal human cell into a malignant cell in all its forms. Results will be concluded after this first proposal of such first kinds of experiments in the Medical Field related to a Common Denominator in Cancer.
The primary objective was to identify and clone novel chromosomal DNA fragments for use as B. anthracis-specific markers. Towards this goal, 300 random primers (RAPD technology, randomly amplified polymorphic DNA) were screened to identify polymorphic loci on the anthrax chromosome. Five such DNA fragments uniquely amplifying from anthrax chromosome were identified and isolated. These fragments were cloned in pCR vector and sequenced. Database (genebank) analysis of one of the cloned probe, VRTC899, revealed the presence of specific chromosomal DNA probe, Ba813 from anthrax. This prove also contains flanking DNA with no homology to known sequences. Availability of signature DNA probes for detection of antrax-causing agent in environmental samples is critical for field application of DNA-based sensor technologies. In conclusion, we have demonstrated application of RAPD technology for identification of anthrax-specific signature sequences. This strategy can be extended to identify signature sequences from other BW agents.
A parallel confocal method including an optical diffractive element, a Dammann grating, is presented. Dammann gratings manufactured with microfabrication technologies have the ability to generate several beams with identical intensity. An optical confocal system combining with a Dammann grating will form multi-channel confocal optical structures, so that it can achieve a planar image instantly without scanning. This parallel confocal fluorescence detection system has the merits of discarding scanning part, compact structure, real time imaging and detection and high S/N ratio, therefore it is suitable for detection of dye-labelled DNA array chips and for other biomedical applications. Structural considerations and design of a parallel confocal fluorescence setup and experimental results of detecting a dye-labeled DNA array chip are presented in this paper.