No abstract

The analysis of resonant-type antennas based on the fundamental infinite wavelength supported by certain periodic structures is presented. Since the phase shift is zero for a unit-cell that supports an infinite wavelength, the physical size of the antenna can be arbitrary; the antenna's size is independent of the resonance phenomenon. The antenna's operational frequency depends only on its unit-cell and the antenna's physical size depends on the number of unit-cells. In particular, the unit-cell is based on the composite right/left-handed (CRLH) metamaterial transmission line (TL). It is shown that the CRLH TL is a general model for the required unit-cell, which includes a nonessential series capacitance for the generation of an infinite wavelength. The analysis and design of the required unit-cell is discussed based upon field distributions and dispersion diagrams. It is also shown that the supported infinite wavelength can be used to generate a monopolar radiation pattern. Infinite wavelength resonant antennas are realized with different number of unit-cells to demonstrate the infinite wavelength resonance.

No abstract

Translation of vesicular stomatitis virus (VSV) mRNA, like host mRNA translation, is inhibited in cells infected with poliovirus. To study the mechanism of poliovirus-induced inhibition of protein synthesis, we prepared extracts from poliovirus-infected and uninfected HeLa cells. Poliovirus mRNA was translated in Iysates from both infected and uninfected cells, while VSV mRNA was translated only in the lysate from uninfected cells. Addition of purified translation initiation factors to the extract frosi infected cells showed that one factor eIF4B, could restore VSV mRNA translation in the infected lysate, but did not increase poliovirus mRNA translation. Further experiments involving translation of VSV mRNA in mixed extracts from poliovirus-infected and uninfected cells showed (j) that there was not an excess of an inhibitor of VSV mRNA translation in the infected 1 sate, but (ii) that an activity that caused a slow inactivation oleIF-4B was present in the infected lysate. Inactivation of eIF4B appears to~e the mechanism by which poliovirus -infection causes a selective inhibition of translation. Inhibition of host protein synthesis occurring after virus infection has been demonstrated in many eukaryotic virus-host systems (1). The best studied case of inhibition of protein synthesis is that caused by picornaviruses such as poliovirus, but the mechanism that allows discrimination between host and viral mRNA translation has not been elucidated. Infection by poliovirus results in extensive inhibition of host protein synthesis at the initiation step (2, 3). During poliovirus infection the host mRNAs are not degraded (2, 3) and their capping, methylation, and polyadenylation are not affected (4). Furthermore, translation of vesicular stomatitis virus (VSV) mRNAs is prevented when VSV-infected cells are superinfected with poliovirus (5, 6). VSV mRNA synthesis continues normally in the superinfected cells and the untranslated VSV mRNA can be translated in vitro after purification from the infected cell (6). Also, the kinetics of poliovirus inhibition of host and VSV protein synthesis are identical, suggesting that they occur by the same mechanism (6).In this study we have used translation of VSV mRNA in extracts derived from poliovirus-infected and uninfected HeLa cells to study the mechanism of translation inhibition by poliovirus. VSV directs the synthesis of five mRNAs that encode the five viral proteins (7,8). These mRNAs, like cellular mRNAs, have capped and methylated 5' termini that are important in ribosome recognition (9). In contrast, poliovirus mRNA has a 5' terminus of pUp (10, 11). The evidence presented here indicates that loss of a single initiation factor activity (eIF-4B) can explain the inhibition of VSV and host mRNA translation by poliovirus. Other work has indicated that this factor interacts with the 5' cap structure on mRNA (12). Thus, poliovirus mRNA may bypass the cap-dependent recognitionThe costs of publication of this article were defrayed in part by the payment of page charges. Th...

No abstract