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The optically pumped Cs beam frequency standard under development in our laboratory was first evaluated in 1993. The short term stability was /spl sigma//sub y/(/spl tau/) is 5.5/spl middot/10/sup -13//spl tau//sup - 1/2 /. The accuracy has been estimated to 1.1/spl middot/10/sup -13/, mainly limited by the distributed phase shift. After modification of the cavity, a new evaluation is in progress and is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Feature-based Computer Automated Process Planning applications often suffer from exponential growth of the search space and thus CPU time, with increasing complexity of a part. This paper will explain some methods that were used to improve the response time of a newly developed CAPP system that is capable of generating net-shaped process plans, called non-linear process plans, containing several alternatives. One method to improve the performance is called Opportunistic process planning. The approach consists of dividing the features into two sets: one set, called the important features, is used to generate a process plan; the other features, called non-important features, are added to the process plan afterwards. This generation method highly resembles the reasoning pattern of a human process planner. Another innovative method for performance improvement is called Feature grouping. This method combines features that have strong resemblance, and considers them as only one feature during the process plan generation. Other reasoning methods, described in this paper, are: combined variant/generative planning and constraint-based search. All of the above-mentioned methods allow us to reduce the search space significantly. The developments have been carried out in the framework of the Esprit project 6805, COMPLAN (Concurrent Manufacturing Planning and Shop Control for small batch production). The COMPLAN CAPP system is able to cover a wide workpiece spectrum (customizable towards specific needs). It has been intensively tested for three workpiece families (i.e. hydraulic valves, bending tool-knives and prismatic parts) of a pilot end-user, a producer of sheet metal machinery. The system can be easily extended towards other part spectra. Also the embedded process-planning knowledge is easy to configure or alter.
While 25 compounds have been formally licensed for the treatment of HIV infection (AIDS), only seven licensed products are currently available for the treatment of chronic hepatitis B virus (HBV) infection: interferon-α, pegylated interferon-α, lamivudine, adefovir (dipivoxil), entecavir, telbivudine and tenofovir (disoproxil fumarate). In contrast to the treatment of HIV infections where the individual drugs are routinely used in combination, for the treatment of chronic HBV infection the individual drugs are generally used in monotherapy. In principle, combination drug therapy should allow reducing the likelihood of drug-resistant development.
Although the presence of free 2'-hydroxyl groups in both strands of a double-stranded RNA complex has been recognized as one of the major requisites for the interferon inducing activity of double-stranded RNAs, we have found a particular analog of (I)n·(C)n, in which the 2'-hydroxyls of the purine strand were replaced by azido groups [(dIz)n·(C)n], to be exquisitely effective in inducing interferon. Various other 2'-azido analogs, i.e. (dIz)n·(brC)n, (I)n·(dCz)n, (dAz)n·(U)n, (dAz)n·(rT)n and (dAz)n·(dUz)n were inactive as inducers of interferon. Thus we come to the conclusion that the interferon inducing system recognizes total threedimensional conformation of the double-stranded RNA.
These last years, numerous molecules have been developed to face HIV-1 infection. All viral replication steps are potential targets for new molecules. The most potent inhibitors of virus-cell adsorption are represented by the different sulfated, sulfonated and carboxylated polymers among which aurintricarboxylic acid (ATA). The soluble CD4 are also potent inhibitors of viral adsorption in vitro. Many compounds are active at the level of the reverse transcriptase (RT), particularly the 2',3'-dideoxynucleosides, represented by the three currently most used drugs in the clinic, AZT, ddC and ddI. The acyclic nucleoside phosphonates (PMEA, PMEDAP) have shown a broad spectrum activity against many human and animal retroviruses, and also unique pharmacological properties allowing infrequent administration. Finally, most recently, highly potent activity, without toxicity, has been demonstrated by TIBO, HEPT and other HIV-1 RT-specific inhibitors.
No abstract is provided for this article.
The discovery of interferon (IFN), as an antiviral substance, by Isaacs and Lindenmann in 1957 De Somer's original attempts were aimed at determining the mode of action of IFN [2], whereas Merigan's work focused on trying to understand the role of IFN in human viral diseases
