7-(Dialkylamino)coumarin-4-yl]methyl-Caged Compounds as Ultrafast and Effective Long-Wavelength Phototriggers of 8-Bromo-Substituted Cyclic Nucleotides

[7-(Dimethylamino)coumarin-4-yl]methyl (DMACM) and [7-(diethylamino)coumarin-4-yl]methyl (DEACM) esters of 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) are described as novel caged compounds for 8-bromo-substituted cyclic nucleotides. Synthesis is accomplished by treatment of the free acids of the cyclic nucleotides with the corresponding 7(dialkylamino)-substituted 4(diazomethyl)coumarins. Irradiation of the DMACM- and DEACM-caged cyclic nucleotides with UV light stimulates the release of the cyclic nucleotides within roughly a nanosecond. The new caged compounds are resistant to hydrolysis in aqueous buffers and exhibit long-wavelength absorption properties with maxima at 400 nm, high extinction coefficients, and high quantum yields (0.15-0.31). Their favorable properties render these compounds the most efficient and rapid phototriggers of 8-bromo-substituted cyclic nucleotides known. The usefulness of the compounds for physiological studies under nondamaging light conditions was examined in HEK293 cells expressing the alpha subunit of the cyclic-nucleotide-gated (CNG) channel of cone photoreceptors (CNGA3) and of olfactory neurons (CNGA2) by using confocal laser scanning microscopy and the patch clamp technique.     

The UK Cleanfeed system — Lessons for the German debate?

As readers of this journal will of course know, the Zugangserschwerungsgesetz has caused considerable and often very profound debate in Germany about the limits of legal and technological interference with the freedom of access to information, culminating in the temporary refusal of the President to sign the law into action. In the UK by contrast, a core aspect of this law, the technical prevention of access to sites hosting illegal content by ISPs, was introduced through the so called “Cleanfeed system” as early as 1996, with little or no public debate, and bypassing by and large all parliamentary procedure and scrutiny. This article has a threefold aim: First, it gives a brief account of the history and implementation of the UK Cleanfeed system1; second, it explains some of its more unusual aspects by putting them into the historical and constitutional context of policing in the UK, and third, it highlights those experiences made with the system that are of direct relevance for the German discussion.     

Report on the 2nd International Summer School on Network and Service Management (ISSNSM’08)

This report summarizes the 2nd International Summer School on Network and Service Management (ISSNSM’08), which was held at the Communication Systems Group (CSG) of the Department of Informatics (IFI), University of Zurich, Switzerland, on 2–6 June 2008. Supported by the European FP6 Network of Excellence for the Management of Internet Technologies and Complex Services (EMANICS), the ISSNSM presented within 5 days eight different topics, covering the areas of (1) security, (2) virtualization and simulations, and (3) network monitoring and management. All of these run for a full or half day, including a short theoretical introduction and larger practical lab course components, respectively.

Relationships between pushdown automata with counters and complexity classes

In this paper a machine model is defined whose access to the storage cells is controlled by means of address registers. It is shown that every set acceptable by such a machine within time boundcn ^p,p , is accepted by a deterministic 2p-head two-way pushdown automaton which has additional counters of length log₂ n. On the other hand every set acceptable by a deterministicp-head two-way pushdown automaton can be accepted by this machine model within time boundcn ^plog₂ n. A result similar to one of the main theorems (theorem 4) of this paper has been proved also by S. A. Cook. Both proofs are based on the same idea but have been found independently.     

Multipurpose modular experimental station for the DiProI beamline of Fermi@Elettra free electron laser

We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011.