Compensating for moderate effective throughput at the desktop

This article presents the design and development of a networking system architecture targeted to support high-speed TCP/IP communication over ATM. The discussed architecture has been developed in the form of an integrated system which incorporates state-of-the-art software and hardware subsystems, and an OC-12c ATM adapter (622 Mb/s). Moreover, the design of this embedded system has been based on the Chorus real-time operating system, which, in turn, hosts an accelerated TCP/IP protocol stack over ATM. Furthermore, the embedded system board has been developed according to the PCI specification to easily be plugged into a host platform. In addition, the OC-12c ATM adapter subsystem has been designed and developed in order to also be plugged into the same host. The developed architecture has proven very efficient and reliable, providing high-throughput and low-latency bulk data communications. The measured performance on an OC-3c-based (155 Mb/s) testbed has shown that an optimally implemented TCP/IP stack, hosted by a real-time kernel and coupled with an ATM adapter, offers a robust desktop platform for high-speed end-to-end communications. The main feature of the accelerated TCP/IP protocol stack is the out-of-band processing of control and data information. The protocol accelerator embedded system processes the TCP/IP headers and accomplishes checksum computations, while data is transferred from the host's user memory space directly to the network. Finally, for validation purposes, the prototype system has been incorporated in an existing networking infrastructure targeted to support mass storage applications     

RF performance of SiC MESFET's on high resistivity substrates

State-of-the art SiC MESFET's showing a record high f_max of 26 GHz and RF gain of 8.5 dB at 10 GHz are described in this paper. These results were obtained by using high-resistivity SiC substrates for the first time to minimize substrate parasitics. The fabrication and characterization of these devices are discussed     

Chemical composition of developing carob pods

Chemical analyses of the fruit of two carob varieties were made during 1969 at fortnightly intervals during the six months preceding harvest. The sugar content of the pods increased rapidly from the end of May onwards while the crude protein and crude fibre contents decreased. Sucrose increased from about 2·5% in late March to about 35% at harvest in mid-August. The main increase in sugar content occurred after the pod had attained its full size in late May.     

Removal of zinc residues from apple leaves by hydrochloric acid and leaching of other nutrients in the process

Leaves sampled from “Lord Lambourne”, “Starking Delicious” and “Golden Delicious” apple trees sprayed with zinc sulphate were treated in various ways (a detergent wash, an acid wash, a 10 min, or a 20 min soak in N-HCl). Leaves which were soaked had the lowest zinc content, and this was attributed to “internal” zinc; the other treatments left behind more zinc, and the increase was attributed to “external” and/or easily leachable zinc. A single spray (0.3% ZnSO₄. H₂O) increased “internal” zinc contents to ～50 parts/10⁶, and three sprays to ～150 Parts/10⁶. Soaking the leaves in N-HCl for 10 min leached out K, Mg and Mn but not N, P or Fe. As with zinc, soaking for 20 min did not, except in one case, leach out any additional amounts of nutrients. It is suggested that there may be an “easily leachable” fraction of K, Mg, Mn, and possibly Zn, which is removed from the leaves by the 10 min soak in N-HCl.     

4H-SiC MESFET's with 42 GHz fmax

We report for the first time the development of state-of-the-art SiC MESFETs on high-resistivity 4H-SiC substrates. 0.5 μm gate MESFETs in this material show a new record high f_max of 42 GHz and RF gain of 5.1 dB at 20 GHz. These devices also show simultaneously high drain current, and gate-drain breakdown voltage of 500 mA/mm, and 100 V, respectively showing their potential for RF power applications