George N. Lewis

Effects of background fluorescence in fluorescence molecular tomography

Recent advances in optical imaging systems and systemically administered fluorescent probes have significantly improved the ways by which we can visualize proteomics in vivo. A key component in the design of fluorescent probes is a favorable biodistribution, i.e., localization only in the targeted diseased tissue, in order to achieve high contrast and good detection characteristics. In practice, however, there is always some level of background fluorescence present that could result in distorted or obscured visualization and quantification of measured signals. In this study we observe the effects of background fluorescence in tomographic imaging. We demonstrate that increasing levels of background fluorescence result in artifacts when using a linear perturbation algorithm, along with a significant loss of image fidelity and quantification accuracy. To correct for effects of background fluorescence, we have applied cubic polynomial fits to bulk raw measurements obtained from spatially homogeneous and heterogeneous phantoms. We show that subtraction of the average fluorescence response from the raw data before reconstruction can improve image quality and quantification accuracy as shown in relatively homogeneous or heterogeneous phantoms. Subtraction methods thus appear to be a promising route for adaptively correcting nonspecific background fluorochrome distribution.

Video evidence on the effectiveness of patriot during the 1991 gulf war

Many of the Patriot‐Scud engagements during the 1991 Gulf War were recorded on video by news media camera crews. These videos are a unique and important source of information on Patriots performance that has been completely ignored by the US Army in performing its assessments of Patriots performance. The videos show many examples of Patriots missing their Scud targets, as well as a few examples of Patriots hitting Scuds but failing to destroy the Scud warhead. The videos also contain information about the nature of the Scud targets, and also about other important occurrences, such as Patriots diving into the ground. The videos we have been able to obtain contain no unambiguous evidence that Patriot destroyed even one Scud warhead. Rather, they contain substantial evidence that Patriots success rate was very low, and provide a record of Patriot performance that clearly is inconsistent with the US Armys current claim that Patriot destroyed 52 percent of the Scud warheads that it engaged.

The European Missile Defense Folly

The United States plans to protect itself from emerging missile threats by building a Europe-based missile defense system. Like its predecessors, the system has serious technological deficiencies.

The Continuing Debate on National Missile Defenses

Over the past several years, the Clinton administration has developed a national missile defense (NMD) system, the first phase of which could be operational sometime in the second half of this decade. President Clinton was scheduled to decide this fall whether to begin deployment of the system next spring; on 1 September he announced that he did not have “enough confidence in the technology, and the operational effectiveness of the entire NMD system, to move forward to deployment,” and would leave that decision to his successor. Whether or not to go forward with deployment of this system—or any other one, perhaps based on different technologies—will be a central policy concern for the next administration.

Long‐range nuclear cruise missiles and stability

Long-range nuclear-armed cruise missiles are highly accurate and are capable of reaching most targets within the United States and the Commonwealth of Independent States (CIS) from launch points beyond their borders. Neither the United States nor the CIS has air surveillance systems capable of providing reliable warning against cruise missiles. Thus it is possible that a small-scale cruise missile attack could go entirely undetected until the nuclear weapons arrived over their targets. Such an attack could destroy the other countrys entire strategic bomber force on the ground and severely damage its strategic command and control system, perhaps to the point of endangering the ability of its ICBM force to be launched on warning. This capability makes long-range nuclear cruise missiles potentially one of the most destabilizing of all nuclear weapons.

Dispelling myths about verification of sea-launched cruise missiles.

It is widely believed that an arms control limit on nuclear-armed sea-launched cruise missiles would be nearly impossible to verify. Among the reasons usually given are: these weapons are small, built in nondistinctive industrial facilities, deployed on a variety of ships and submarines, and difficult to distinguish from their conventionally armed counterparts. In this article, it is argued that the covert production and deployment of nuclear-armed sealaunched cruise missiles would not be so straightforward. A specific arms control proposal is described, namely a total ban on nuclear-armed sea-launched cruise missiles. This proposal is used to illustrate how an effective verification scheme might be constructed.

Limitations on ballistic missile defense—Past and possibly future

ABSTRACT The ABM Treaty is unlikely to be revived any time soon. But it is possible that restraints on US deployment of ballistic missile defenses could make them seem less threatening to the effectiveness of Russia’s and China’s nuclear deterrents and set the stage for discussions about ways to preserve and even advance nuclear arms control. The proposed restraints are on systems designed to intercept warheads outside the atmosphere. Such systems are of little value in any case because they can be easily deceived by decoys and other countermeasures.