Damping of longitudinal plasma oscillations

Attenuation of electron oscillations in a fully ionized plasma is investigated by solving linearized kinetic equation without external fields. The general dispersion relation for longitudinal plasma oscillations is obtained using the BGK model. Damping due to electron ion collisions is obtained with a correction term. It is also observed that damping rate decreases ask increases, which is in agreement with McBride.     

Interaction of electromagnetic waves with anisotropic collisional plasma half space

Interaction of electromagnetic waves penetrating into anisotropic semi-infinite collisional plasma embedded in a uniform external magnetic field is studied using half range Fourier transforms. General field equations are developed for fractionally accommodating boundary and a particular case of specular reflection is discussed both for right handed as well as left handed circularly polarized modes. Anisotropy effects are found to be more prominent in the continuum mode of field component. Anisotropy as well as collisions make the field to attain a constant value at a shorter distance. Left handed polarized modes are found to be more penetrating than right handed modes. Surface impedance is calculated and effects of collisions as well as anisotropy are discussed.     

Penetration of waves into semi-infinite collisional plasmas

Penetration of longitudinal and transverse fields into a semi-infinite collisional plasma with fractionally accommodating boundary, having specular and diffuse reflecions is studied. The penetration of longitudinal field was studied by Landau and recently by Mason which was extended for transverse waves by Gupta and Varma. The theory is extended for collisions between electrons and ions according to B.G.K. Model, and its resemblence with metals for electrons and holes, gives its practical significance. The reflection coefficients and surface impedence are observed. The results are compared with non-collisional cases and it is observed that depth of penetration for collisional plasma decreases.     

A Beat-to-Beat Heart Rate Meter

A new technique for computing beat-to-beat heart rate using a programmable counter is described. The circuit used is much less complex and consequently more economical than the circuits described elsewhere in the literature. Yet, it achieves acceptable accuracy in the rate measurements. The circuit can be conveniently modified to measure very low-frequency physiological phenomena such as respiration rate.     

Transmission electron microscopy of saturated hydrocarbon block copolymers

Contrast for transmission electron microscopy (TEM) of microphase-separated saturated hydrocarbon diblock copolymers has been obtained using ruthenium tetroxide (RuO₄). This technique exploits differences in the rate of transport of the oxidizing stain in rubbery amorphous versus semicrystalline, or glassy, microdomains. Rapid quenching from above the melting (T_m), or glass transition (T_g) temperature is shown to preserve the equilibrium melt morphology in poly(ethylene)-poly(ethyl-ethylene) (PE-PEE), poly(ethylene)-poly(ethylene-propylene) (PE-PEP), and poly(vinylcyclohexane)-poly(ethyl-ethylene) (PVCH-PEE) diblock copolymers; PE melts at 108°C, PVCH is glassy up to about 140°C, while PEE and PEP remain rubbery down to approximately-20°C and ?56°C, respectively. Treatment of ultrathin sections of the quenched specimens with RuO₄ vapor led to welldefined TEM images, that revealed microdomain type and order. These results are consistent with SANS data taken under equilibrium conditions. © 1995 John Wiley & Sons, Inc.     

Characterization and evaluation of TCP and UDP-based transport on real networks

StandardTcp (RenoTcp) does not perform well on fast long distance networks, due to its AMD congestion control algorithm. In this paper we consider the effectiveness of various alternatives, in particular with respect to their applicability to a production environment. We then characterize and evaluate the achievable throughput, stability and intra-protocol fairness of differentTcp stacks (Scalable,Hstcp,Htcp, FastTcp, Reno,Bictcp, hstcp-lp andLtcp) and aUdp based application level transport protocol (Udtv2) on both production and testbed networks. The characterization is made with respect to both the transient traffic (entry and exit of different streams) and the steady state traffic on production Academic and Research networks, using paths withRtts differing by a factor of 10. We also report on measurements made with 10 Gbit/secNics with and withoutTcp Offload Engines, on 10 Gbit/s dedicated paths set up forSc2004.