Electrostatic force microscopy of self-assembled peptide structures

In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In particular we use EFM to investigate the structures of diphenylalanine peptide tubes, particles, and CSGAITIG peptide particles placed on pre-fabricated SiO(2) surfaces with a backgate. We show that the cavity in the peptide tubes could be due to the presence of water residues. Additionally we show that self-assembled amyloid peptides form spherical solid structures containing the same self-assembled peptide in its interior. In both cases transmission electron microscopy is used to verify these structures. Further, the limitations of the EFM technique are discussed, especially when the observed structures become small compared with the radius of the AFM tip used. Finally, an agreement between the detected signal and the structure of the hollow peptide tubes is demonstrated.     

Making voice knowledge pervasive

Until recently, voice knowledge has been ignored as a tangible information asset, mostly because of difficulties in collecting and organizing it. Using the most pervasive device available today - the telephone - and advances in speech recognition technology and voice markup languages, we have built a service architecture that transforms the telephone from a simple communication medium to an information medium.     

Synchronization and recovery in a client-server storage system

Client-server object-oriented database management systems differ significantly from traditional centralized systems in terms of their architecture and the applications they target. In this paper, we present the client-server architecture of the EOS storage manager and we describe the concurrency control and recovery mechanisms it employs. EOS offers a semi-optimistic locking scheme based on the multi-granularity two-version two-phase locking protocol. Under this scheme, multiple concurrent readers are allowed to access a data item while it is being updated by a single writer. Recovery is based on write-ahead redo-only logging. Log records are generated at the clients and they are shipped to the server during normal execution and at transaction commit. Transaction rollback is fast because there are no updates that have to be undone, and recovery from system crashes requires only one scan of the log for installing the changes made by transactions that committed before the crash. We also present a preliminary performance evaluation of the implementation of the above mechanisms. Edited by R. King. Received July 1993 / Accepted May 1996     

Selective replication for content management environments

Content management applications typically depend on information stored in both relational database tables and operating system files. Often, content providers replicate all or parts of the available database data and associated files to increase application availability, address resource constraints and costs, or better support geographically dispersed and mobile users. This article presents a solution that addresses integrated and selective database and file replication in the context of an enterprise voice portal. The solution is transparent to existing applications and imposes minimal storage overhead.     

A new MONERIS in-Stream Retention Module to Account Nutrient Budget of a Temporary River in Cyprus

The nature of the nutrient budget for temporary rivers differs from that for permanent rivers because of the restricted nature of flow, the lack of adequate dilution, and weather conditions which are conducive to the development of algal blooms. We analyse the nutrient budget of three tributaries of a temporary river in Cyprus, the Kouris, with the aid of the MONERIS model. MONERIS in-stream retention module was modified to account for a 1-dimensional advection - dispersion pollutants transport rather than the general mass balance equation for mixed reactors. TRS plot classified Kryos stream as an Intermittent flow – Dry (I-D) stream (hydrologically altered) and Kouris and Limnatis as Intermittent – Pool (I-P) streams that need different lumped parameterization in MONERIS simulation. Point sources are important for nitrogen (64 %) and phosphorous emissions (22 %), and diffuse sources for nitrogen via erosion (15 %) and free grazing (12 %) and for phosphorous via free grazing (8 %). We estimate that around 40 % of N and 88 % of P entering streams is retained in the stream. An analysis of the model uncertainty and sensitivity to input data indicates that MONERIS model, even in semi-arid areas, may be used for the purpose of managing river basins.