• As reported in the British journal Nature, researchers at the Mayo Clinic (Rochester, MN) have found that when people lie the blood flow around their eyes increases, and so have proposed that screeners using high-definition, heat-sensing cameras could determine if someone was telling the truth or a lie. Preliminary experiments have been conducted using this technology and the findings are that the accuracy of this system is slightly higher than that of polygraphs. In the experiment the camera identified 75% of the "guilty" subjects and 90% of the "innocent" subjects.
  The Mayo Clinic study authors' hypothesis is that this blushing is part of the "fright or flight response", which can signal willful deception. Skeptics point to the possibility that the physiological changes could be due to anxiety and not guilt. Others have noted that the number of subjects used in the experiment is too small to determine if this truly is meaningful. However, Honeywell has patented this system, and tests will be ongoing to see if this will work in real-life situations.
  Note: even if this system is validated and achieves the rates of accuracy stated, its use in isolation would be less than useful due to the base rate fallacy (see OPED4 for an explanation). However, as a part of a structured screening process it could prove valuable. First, profiling - see OPED2 - would reduce the population needing further screening, and this would be further reduced by use of this system, so that interview, individual search, etc. would need to be performed on a manageable number of people.

• Another technology showing promise is using an ion mobility spectrometer to detect minute traces of explosives. The Sandia National Laboratories has developed a portal for airport use that closely resembles the existing metal detectors. As the passengers pass through the portal air flows downwards from the top of the portal. Small air jets on the sides agitate the passengers' clothing to dislodge any contamination. The airflow is then pulled into a 'screen preconcentrator' in which the large volume of air is passed through a high-density metal screen. Heavy organic molecules (e.g. trace explosives) are trapped by the screen. The screen is then heated to 200 degrees Centigrade, which converts any collected explosive traces back into a gas that is then passed to the ion mobility sensor. The net effect is that trace explosives from a large volume of air are concentrated by a factor of 100-1000 before passing to the spectrometer for detection, thus increasing the chances of detection. Experiments done at the Alburquerque airport in 1997 were positive... A throughput rate of five passengers/minute was achieved, with a false detection rate of less than one percent (information on the types or quantities of explosives this system can detect were not disclosed for security reasons.) Further refinement of this portal has been underway for several years, and it may be commercially available in the near future.
• A problem with airport screeners is that even well trained security personnel find it difficulty to maintain the requisite level of concentration while watching X-ray scanner screens for long periods. PerkinElmer Instruments (Boston, MA) has developed a software package known as TIP - Threat Image Projection to combat this and to ensure that screeners stay alert. The software can project images of guns, knives, or explosive devices on the images of the bags that are passing through the scanners. This is used to improve the screeners' abilities, as well as to periodically check on their alertness.
• Another promising technology is Quadropole Resonance. It is known that when explosives are bombarded with certain radio frequencies the nitrogen compounds in the explosives vibrate, and that QR scanners can then detect these vibrations. This technology is being adapted to scan trucks, shipping containers, etc. The truck or container is bombarded with low-power radio waves of specific frequencies. If explosives are present their nitrogen compounds begin to vibrate, and very sensitive radio receivers that surround the truck pick this up. A computer system can then identify the explosive present by comparing the signals captured against a database of known compounds. Since the radio waves do not effect people and are not distorted by steel shipping containers, entire vehicles could be scanned at one time.

In conclusion, numerous technologies are being developed that can help in increasing security levels. Science and technology can provide tools that may contribute to increased security and the fight against terrorism, but there is no "magic bullet". What is necessary is the deployment and use of multiple technologies to provide a systematic, multi=layered defense.